**Report on the Mars Drilling Feasibility Workshop**

######### of February 27-28, 2001

######### 

**Mars '07 Drilling Feasibility Team:**

Dave Beaty, JPL

Sylvia Miller, JPL

Remo Bianchi, CNR-IAS

Jim Blacic, LANL

Geoff Briggs, ARC

Steve Clifford, LPI

Angioletta Coradini, CNR-IAS

Maria Cristina De Sanctis, CNR-IAS

Ben Dolgin, JPL

Mike Duke, LPI

Sylvie Espinasse, ASI

Steve Gorevan, Honeybee Robotics

Sam Kim, JPL

P. G. Magnani, Tecnospazio

Rocco Mancinelli, NASA ARC

Hum Mandell, JSC

Doug Ming, NASA JSC

Deb Neubek, JSC

Quinn Passey, Exxon-Mobil

Edoardo Re, Tecnospazio

Sue Smrekar, JPL

Brian Wilcox, JPL

REV. 1

June 1, 2001

**Table of Contents**

#### 

#### Introduction

#### Workshop

#### Discussion

#### Summary Conclusions

> **Appendices**
>
> **A. Workshop Participants**
>
> **B. Drilling white paper from Los Alamos**
>
> **C. Drilling white paper from JSC/Baker Hughes**
>
> **D. Drilling white paper from Honeybee Robotics**
>
> **E. Drilling white paper from ASI**
>
> **F. Drilling white paper from JPL-Brian Wilcox**
>
> **G. Drilling white paper from UTD/JPL**

#### 

#### I. Introduction

On February 27-28, 2001, a workshop was conducted on the feasibility of
drilling on Mars, with the 2007 Smart Lander having been identified as
the first potential opportunity. The workshop was attended by
approximately 40 participants, including a multi-disciplinary group of
Mars scientists, representatives from six engineering teams who had been
analyzing the issues involved in Mars drilling, independent drilling
experts from outside the Mars community, engineers involved in robotic
spacecraft design and operation (specifically including representatives
from the 2007 Smart Lander pre-project), an IT expert, and programmatic
representation from the Mars Program Office, ASI, and NASA HQ. The
workshop included a substantial contingent from Italy, as well as from
the industrial sector. The purpose of this report is to summarize the
results of the workshop and to document supporting material.

**II. Workshop**

Two full days, February 27 and 28, were devoted to the workshop. It took
place at the Lunar and Planetary Institute in Houston, Texas. A list of
participants appears in Appendix A, although one or two people dropped
out at the last.

The agenda is given in Table 1. It was structured to achieve responses
to specific desired outcomes as follows:

######## Engineering Desired Outcomes {#engineering-desired-outcomes .unnumbered}

1)  What performance characteristics in 2007 (e.g. depth, sampling
    capability) are achievable as a function of mass, power, and time on
    the surface?

2)  What performance characteristics are achievable next decade (e.g.
    depth, sampling capability) as a function of mass, power, and time
    on the surface?

3)  What are the principal engineering trades between drilling
    performance and surface mobility? What are the issues involved with
    coupling drilling and mobility?

4)  What test results will be needed to validate engineering designs
    prior to a mission CDR?

5)  What components need to be included in a technology R&D program to
    achieve this performance?

######## Science Desired Outcomes {#science-desired-outcomes .unnumbered}

1)  Communicate prioritized subsurface science investigations and
    overall value of science as a function of three parameters that
    affect drilling engineering:

-   Depth of penetration

-   Mobility, and the possibility of multiple holes

-   Different strategies for data acquisition (MWD, MAD, logging, sample
    recovery, etc.).

**Table. 1 Mars Drilling Feasibility Workshop Agenda**

###### Tuesday, February 27

  --------- -------------- -----------------------------------------------
  8:00      Beaty, Miller  Welcome, introductions

  8:20      Beaty, Miller, Review scope and framework of current
            Lavery         feasibility study, desired outcomes of this
                           meeting, how we will achieve this outcome, ITAR
                           briefing

  9:00      Thurman        Overview of the 2007 mission, spacecraft
                           constraints

  9:45      Clifford et    Possible science justification and priorities
            al.            for a 2007 drill

  10:45                    Physical parameters of the martian surface that
                           affect drilling

  11:15     Blacic         Engineering analysis #1

                           

  1:00      Mandell        Engineering analysis #2

  1:40      Gorevan        Engineering analysis #3

  2:20      Flamini        Engineering analysis #4

  3:00      Wilcox         Engineering analysis #5

  3:40      Dolgin         Engineering analysis #6

  4:20      Sam Kim        Possible science instruments

  4:45      Beaty, Miller  Discussion, wrap-up of Day #1
  --------- -------------- -----------------------------------------------

###### Wednesday, February 28

  --------- -------------- -----------------------------------------------
  8:00      Special Topics Arnold Law, Quinn Passey, Yongchun Tang
                           results, other?

  9:00      All            Break-out Session #1: Drilling depth as a
                           function of mass, power

  11:00     All            Break-out reports, full group discussion

                           

  1:00      All            Break-out Session #2: Technology planning

  1:00      All            Break-out Session #3: Science data acquisition

  1:00      All            Break-out group #4: Programmatic issues

  3:00      All            Break-out reports

  4:00      Beaty, Miller  Overall discussion, conclusion

                           
  --------- -------------- -----------------------------------------------

2\) Understand issues involved in integration of scientific instruments
and the drilling system.

(It was recognized that the audience for this workshop was not the one
to debate science priorities and values, but the science sub-group
reported on their findings.)

######## Programmatic Desired Outcomes {#programmatic-desired-outcomes .unnumbered}

1)  What do we need to know before we fly the first drill?

2)  What do we need to learn in the first drilling mission to minimize
    risk in the next drilling mission?

3)  Are there engineering elements of a possible 2007 drill that could
    feed-forward into a possible deeper drilling mission next decade?

######## Spacecraft/Mission Desired Outcomes {#spacecraftmission-desired-outcomes .unnumbered}

1)  Develop preliminary information on the requirements that might be
    placed by the drilling system on the spacecraft and mission.

2)  Are there any show-stoppers?

Breakout sessions were held to address the Engineering, Scientific, and
Programmatic desired outcomes. Items addressing the Spacecraft/Mission
desired outcomes were noted on a dedicated flip chart as they arose.

All of the presentation material, breakout session reports, flip chart
material, and other information from the workshop can be found at the
following URL:

<http://mmolib.jpl.nasa.gov/dscgi/ds.py/View/Collection-69>

User name "subsurface" and password "subsurface" are required.

The morning after the workshop, Baker Hughes hosted a 2-hour tour of
their drilling facility located on Rankin Road in north Houston.

**III. Discussion**

###### [Scientific objectives of drilling]{.underline}

Although the science value of accessing the martian subsurface increases
with depth, it does not increase uniformly. Subsurface access beginning
with 1-2 meters is scientifically valuable. However, some investigations
(e.g., heat flow) require approximately a 5 m hole, and several critical
investigations (astrobiology, the search for frozen water, and accessing
local bedrock) require penetration capability of 10-20 meters to have a
reasonable chance of success. The science team involved in this workshop
recommended that if at all possible, the first drilling mission be
designed for a [penetration of at least 20 meters]{.underline}.

Detailed analysis of drilling-related science objectives, priorities,
and tradeoffs are contained in a white paper entitled "Science Rationale
and Priorities for Subsurface Drilling in '07 (final report)." It, along
with the associated Appendix I, can be found at the following URL:

<http://mmolib.jpl.nasa.gov/dscgi/ds.py/View/Collection-67>

User name "subsurface" and password "subsurface" are required.

###### [What is the depth of penetration that can reasonably be expected from a Mars drill?]{.underline} 

White papers were prepared by the six drilling engineering teams. They
are included here as Appendices B through G. They can also be found at
the following URL:

<http://mmolib.jpl.nasa.gov/dscgi/ds.py/View/Collection-77>

with the same username and password just mentioned.

As well as describing their drilling concepts (some described more than
one), the authors of the white papers were asked what depth their drill
could reach for each of 4 cases as follows:

  ------------------- ----------- ------------ ------------- -------------
                      Case 1      Case 2       Case 3        Case 4

  Mass, kg            100         100          150           50

  Day Power, w-hr     200         220          600           200

  Night Power, w-hr   75          220          600           75

  Mission lifetime    0.3         3            3             0.5
  (yrs)                                                      
  ------------------- ----------- ------------ ------------- -------------

Given 50 kg and 275 watt-hours per sol, which may be possible from the
2007 Smart Lander, there is a strong consensus that a [depth of 20 m can
be reached with reasonable levels of risk]{.underline} using any of
several different designs. Most of these designs are based on a heritage
of existing technology that would need to be adapted for space
application. With reasonable budgets, these adaptations can be completed
on a schedule consistent with the 2007 mission timeline.

Two innovative designs were presented which have the potential to go
significantly deeper than 20 m given the same mass, but they rely on
untested technology. These may or may not be ready in time for 2007.

If mass is limited to 25 kg, drills would probably be limited to 1-2 m
depth, and two such designs have advanced TRL levels. There was a
feeling that subsurface access is probably not reasonable if mass is
reduced below about 20-25 kg.

Some discussion took place on possible next decadal deeper drilling
using more mass (75-150 kg) and more power (400-800 watt-hours per sol),
but a consensus on realistic depth targets were not reached. Numbers
between 200 m and 5 km were put forward, but without much discussion or
validation.

The completion of any drilling mission is potentially limited if the
time it takes to reach its total depth is comparable to or exceeds the
mission lifetime. There was a consensus that given 275 watt-hours per
sol (as discussed above for 2007), a penetration rate of 0.5 to 1.0
meters/day is reasonable for planning purposes. This means that for a 20
meter hole, drilling operations would require 20-40 sols (although
additional margin would obviously be prudent).

###### *Data acquisition strategy*

The relative merits of four different categories of data acquisition
were debated at length: MWD (measurement while drilling), MAD
(measurement after drilling), wireline logging (lowering instruments
after the drill has been removed), and sample collection and analysis in
a robotic lab at the martian surface. In all of the discussions, it was
felt that data acquisition strategies depend heavily on the acquisition
of subsurface samples, and their analysis at the martian surface.
However, a significant suite of MWD logs, including temperature, gamma
ray, neutron/density, and IR spectrometer, were also recommended.
Additional instruments (especially for heat flow) should be emplaced in
the walls of the hole after drilling is completed.

Several instruments needed to support a Mars drilling mission would need
to be adapted from terrestrial application to space application. This is
especially true of borehole instruments.

###### *What technology R&D program is needed to support development of Mars drills?* 

A number of technology needs were identified to achieve a 20 meter hole
in 2007, but the highest priority are cuttings removal, bit issues
(wear, replacement, design), and hole casing. There was consensus that
this technology can be advanced to TRL-6 by the end of 2003, but work
would need to begin soon. (A FY01 technology competition resulted in
eight awards in May, totaling \$950K, for drilling-related technology
work.)

For a next decadal mission to 200 m, the highest priority technology
issues are bit issues (wear, replacement, design) and technology to
reduce the bore size, and hole casing. For a 5 km hole, the highest
priority issues are drill autonomy, bit issues, and cuttings removal. No
time or cost estimates were produced for either of these.

###### *Programmatic questions*

What new information is needed before the first drill is flown? We [must
have]{.underline} Earth-based testing. We are not aware of any data from
Mars that is required prior to the first drilling mission. However,
certain information from prior missions would be [highly
desirable]{.underline}, including: orbital geophysics for site
selection, and the coefficient of friction from the 2003 Mars
Exploration Rovers (MER) Rock Abrasion Tool. Advance information from
the drilling mission itself would include a camera to view the spud
point (the point where drilling begins), and possibly local geophysics.

What do we need to learn in the first drilling mission to minimize risk
in the next drilling mission? A wide variety of information about
drilling performance (power consumption, torque, rate of penetration,
visual inspection) must be returned from the first drilling mission. In
addition, we need engineering demonstrations of certain critical systems
(e.g., sample recovery and instrument performance).

Can we use one system for both shallow and deep drilling? It is
desirable to test technology for deep holes by using it first in
shallower holes. However, the technology that is ideal for a shallow
hole may not be ideal for a deep hole.

###### *Relationship of drilling and mobility*

In general, a single deeper hole is scientifically more valuable than
multiple shallower holes. However, limited mobility (e.g., 1 meter)
would be considered an asset to avoid local surface hazards. This could
be achieved by having the option to deploy the drill on more than one
location on the lander. Longer-range mobility (e.g., 10-100 m) would be
desirable, especially if geophysical data about the shallow subsurface
could be acquired prior to selection of the drilling site.

**IV. Summary Conclusions**

1.  For the 2007 Smart Lander, we conclude that a very powerful science
    package can be organized around a 20 meter drill (mass = 50 kg). Two
    alternatives which would also have value, although significantly
    less than this, would be a 5-8 m drill (mass = 35-40 kg) and a 1-2 m
    drill (mass = 25 kg). There was a consensus that the engineering for
    all three of these drilling systems is sufficiently advanced so that
    drilling, to within acceptable risk levels, could be reasonably
    planned for the '07 mission.

2.  Possible subsurface-related instruments have been identified and
    prioritized, and their mass would be in addition to those listed
    above.

3.  In order to be ready for 2007, however, a significant technology R&D
    program needs to be carried out, beginning immediately. (The \$950K
    distributed this fiscal year is providing critical support. If in
    September 2001 the '07 Science Definition Team recommends drilling
    on the '07 Lander/Rover, plans are in place to award additional
    funding shortly thereafter.)

4.  There is significant scientific interest in a deeper drill (at least
    200 meters) by the middle of next decade. The higher mass involved
    in this would likely require a dedicated mission, and technology
    development would require long-term support.

APPENDIX A

WORKSHOP PARTICIPANTS

Workshop Participants

David W. Beaty

Manager, Subsurface Exploration, Mars Program Office

Jet Propulsion Laboratory, M/S 264-426

4800 Oak Grove Drive

Pasadena, CA 91109

Phone: 818.354.7968

Fax: 818.354.8333

E-mail: <dwbeaty@mail2.jpl.nasa.gov>

Remo Bianchi

CNR-IAS

Via Fosso del Cavaliere, 100

00133 Roma

Italy

Phone: +39-06-49934443

Fax: +39-06-20660188

E-mail: rbianchi@ias.rm.cnr.it

James D. Blacic

MS D443

Los Alamos National Laboratory

Los Alamos, NM 87545

Phone: 505.667-6815

Fax: 505.667-8487

E-mail: jblacic@lanl.gov

Geoffrey Briggs

Center for Mars Exploration

Mail Stop 239-20

NASA Ames Research Center

Moffett Field, CA 94035

Phone: 650.604.0218

Fax: 650.604.1088

E-mail: <gbriggs@mail.arc.nasa.gov>

# Stephen Clifford

Center for Advanced Space Studies

Lunar and Planetary Institute

3600 Bay Area Blvd.

Houston, TX 77058

Phone: 281.486-2146

Fax: 281.486-2162

E-mail: clifford@lpi.jsc.nasa.gov

Brian Derkowski

NASA Johnson Space Center

Mail Code EX13

Houston, Texas 77058

Phone: 281. 483.9987

Fax: 281.483.5800

# E-mail: brian.j.derkowski1@jsc.nasa.gov

Maria Cristina De Sanctis

CNR-IAS

Via Fosso del Cavaliere, 100

00133 Roma

Italy

Phone: +39-06-49934444

Fax: +39-06-20660188

E-mail: cristina@ias.rm.cnr.it

# Benjamin P. Dolgin

Jet Propulsion Laboratory, M/S 82-105

4800 Oak Grove Drive

Pasadena, CA 91109-8099

Phone: 818.354-5017

Fax: 818.393-3254

E-mail: Benjamin.P.Dolgin@jpl.nasa.gov

# Greg Dorais

NASA Ames Research Center, M/S 269-2

Moffett Field, CA 94035

Phone: 650.604-4851

Fax: 650.604-3594

## E-mail: <gadorais@ptolemy.arc.nasa.gov>

Don Dreesen\
MS D443\
Los Alamos National Laboratory\
Los Alamos, NM 87545\
Phone: 505.667-1913

Fax:\
E-mail: dreesen@lanl.gov

Mike Duke

32043 Ponderosa Way

Evergreen, CO 80439

Tel: 303-670-2763

FAX: 303-384-2327

E-mail: <mikeduke@earthlink.net>

Sylvie Espinasse

Viale Liegi, 26

00198 Roma

Italy

# Phone: +39-06-8567299

Fax: +39-068567304

E-mail: <espinasse@asi.it>

William Eustes

Petroleum Engineering Dept.

# Colorado School of Mines

Golden, Co. 80401

Phone: 303.273.3745

Fax: 303.273.3189

E-Mail: <aeustes@mines.edu>

Pete Fontana

Baker Hughes

4 Greenway Plaza

PO Box 2765

Houston, Texas 77252-2765

Phone: 713.232-7417

Fax: 713.232-7039

E-mail: <pfontana@deepwater.com>

Jim Garvin

NASA Headquarters, Code S

Washington DC 20546-0001

Phone: 202.358-1798

Fax: 202.358-3095

E-mail: jgarvin@mail.hq.nasa.gov

Stephen Gorevan, Chairman

Honeybee Robotics, Ltd

204 Elizabeth Street

## New York, NY 10012

Phone: 212-966-0661

Fax: 212-925-0835

E-mail: gorevan@hbrobotics.com

John Hill, President

UTD, Inc.

10242 Battle View Parkway

Manassas, VA 20109

Phone: 703.393.0800

Fax: 703.330.1459

E-mail: JohnHill3@UTDinc.com

# Sam Kim

Jet Propulsion Laboratory, M/S 183-401

4800 Oak Grove Drive

Pasadena, CA 91109-8099

Phone: 818. 354-2477

Fax: 818. 393-2941

E-mail: Soonsam.Kim@jpl.nasa.gov

Dave Lavery

NASA Headquarters, Code S

Washington DC 20546-0001

Phone: 202.358-4684

Fax: 202.358-2697

E-mail: dlavery@mail.hq.nasa.gov

Arnold Law

Director of Engineering

Christensen Products

4446 West 1730 South

P.O. Box 30777

Salt Lake City, UT 84130-0777

Phone: 801.974-5544

Fax: 801.972-6769

E-mail: arlaw@laynechristensen.com

James Macfarlane

Baker Hughes

## 4 Greenway Plaza

PO Box 2765

Houston, Texas 77252-2765

Phone: 713.232-7352

Fax: 713.232-7039

E-mail: <jmacfarlane@deepwater.com>

P. G. Magnani

Tecnospazio S.p..A.

Via Montefeltro, 8

20156 Milano

Italy

Phone: +39-02-3809861

Fax: +39-02-38004469

E-mail: <pgmagnani@tecnospazio.it>

Rocco Mancinelli

Mail Stop 239-4

NASA Ames Research Center

Moffett Field, CA 94038

Phone: 650.604-6165

Fax: 650.604-1088

E-mail: rmancinelli@mail.arc.nasa.gov

Hum Mandell

NASA Johnson Space Center

Mail Code EX

Houston, Texas 77058

Phone: 281.483-3977

Fax: 281.244-7478

E-mail: <humboldt.c.mandell1@jsc.nasa.gov>

William J. McDonald

Maurer Engineering, Inc.

2916 West T.C. Jester

Houston, TX 77018

Phone: 713.683-8227, Ext. 2l0

Fax: 713.683-6418

E-mail: [mcdonald@maureng.com](mailto:maurer@maueng.com)

Sylvia Miller\
Jet Propulsion Laboratory, M/S 264-472\
4800 Oak Grove Drive\
Pasadena, CA 91109-8099\
Phone: 818-354-1062\
Fax: 818.393-3800\
E-mail: Sylvia.L.Miller@jpl.nasa.gov

Doug Ming

## NASA Johnson Space Center

Mail Code SN2

## Houston, TX 77058

Phone: 281.483-5839

Fax: 281.483-5839

E-mail: <douglas.w.ming1@jsc.nasa.gov>

Tom Myrick

## Honeybee Chief Engineer

Honeybee Robotics, Ltd

204 Elizabeth Street

# New York, NY 10012

Phone: 212.966-0661

Fax: 212.925-0835

# E-mail: [myrick@hbrobotics.com](mailto:douglas.w.ming1@jsc.nasa.gov)

Deborah J. Neubek

Asst. Manager For Integration

NASA Johnson Space Center

Mail Code: EX

Phone: 281.483-9416

Fax: 281.244-7478

E-mail: deborah.j.neubek1@jsc.nasa.gov

Quinn Passey

ExxonMobil Upstream Research Co.

P.O. Box 2189

Houston, TX 77252-2189

Phone: 713.431-4941

Fax: 713.431-6193

E-mail:
[qrpasse@upstream.xomcorp.com](mailto:quinn.r.passey@exxon.sprint.com)

Carl R. Peterson

14 Elm St.

Boxford, MA 01921

Phone: 978-887-2908

E-mail: <stpcrp@aol.com>

Edoardo Re

Tecnospazio S. p. A.

Via Montefeltro, 8

20156 Milano

Italy

Phone: +39-02-380986204

Fax: +39-02-38004469

E-mail: <ere@tecnospazio.it>

# Tom Rivellini

Jet Propulsion Laboratory, M/S 158-243\
4800 Oak Grove Drive\
Pasadena, CA 91109-8099\
Phone: 818.354-5919\
Fax: 818.393-4860\
E-mail: tommaso.p.rivelllini@jpl.nasa.gov

Bill Salisbury

Salisbury & Associates, Inc

E. 8207 Trent Ave.

Spokane, WA 99212

Phone: 509.927-2700

Fax: 509.927-0483

E-mail: bill@SAITECH.com

Eric Slimko\
Jet Propulsion Laboratory, M/S 158-224\
4800 Oak Grove Drive\
Pasadena, CA 91109-8099\
Phone: 818.354-5940\
Fax: 818.393-4860\
E-mail: slimko@caltech.edu

Peter H. Smeallie

Executive Director

Institute for Advanced Drilling

600 Woodland Terrace

Alexandria, VA 22302

Phone: 703.683.1808

Fax: 703.683.1815

E-mail: [smeallie@advanceddrilling.org](mailto:psmealli@tmn.com)

# Jeff L. Smith

Jet Propulsion Laboratory, M/S 301-180

4800 Oak Grove Drive

Pasadena, CA 91109-8099

Phone: 818.354-1064

Fax: 818.393-9815

## E-mail: jlsmith@mail1.jpl.nasa.gov

# Sue Smrekar

Jet Propulsion Laboratory, M/S 183-501

4800 Oak Grove Drive

Pasadena, CA 91109-8099

Phone: 818. 354-4192

Fax: 818. 393-5059

E-mail: Suzanne.E.Smrekar@jpl.nasa.gov

# Sam Thurman

Pre-Project Manager, Mars 2007 Smart Lander

Jet Propulsion Laboratory, M/S 264-440

4800 Oak Grove Drive

Pasadena, CA 91109-8099

Phone: 818. 393-7819

Fax: 818. 393-3035

E-mail: sam.w.thurman@jpl.nasa.gov

# Richard Volpe

Jet Propulsion Laboratory, M/S 198-219

4800 Oak Grove Drive

## Pasadena, CA 91109-8099

Phone: 818.354-6328

Fax: 818.393-5007

E-mail: <volpe@telerobotics.jpl.nasa.gov>

# Brian H. Wilcox

Technical Group Supervisor, Robotics Vehicles Group

Autonomy and Control Section

Jet Propulsion Laboratory, M/S 107

4800 Oak Grove Drive

Pasadena, CA 91109

Phone: 818.354-4625

Fax: 818.354-8172

E-mail: [Brian.H.Wilcox@jpl.nasa.gov](mailto:Brian.H.Wicox@jpl.nasa.gov)

**APPENDIX B**

**DRILLING WHITE PAPER FROM LOS ALAMOS**

Concept for a Drilling System for the Mars 2007 Lander

J. Blacic, D. Dreesen, T. Mockler

## Los Alamos National Laboratory

![](media/image1.jpeg){width="2.2222222222222223in"
height="7.097222222222222in"}

# **Concept Description**

## [Overview]{.underline}

> Based on results of a conceptual systems analysis of shallow drilling
> on Mars^\[1\]^, we propose a concept for drilling and subsurface
> sampling consistent with the resources expected for the 2007 Mars
> Lander. The concept approach is based on traditional mining core
> drilling systems. It employs a series of concentric, drilled-in augers
> that start with a shallow aggressive core head for soil and soft rock,
> and progress with smaller diameter, deeper, less aggressive bits for
> harder rock (Figure 1). High-rotary-speed, low-weight-on-bit (WOB),
> drag bit kerf comminution produces a core sample. The multiple drill
> rods and a thin-walled auger just above the core head serve as well
> casings to isolate and stabilize any unconsolidated material
> penetrated. Four enhancements have been added to a basic hard rock
> mining drill.
>
> \(1\) A micro-percussive motion is added to the rotary kerf drill to
> improve the hard rock drilling efficiency.

\(2\) Auger flights are added to the outside of the drill rods to lift
the cuttings to the surface on the first drill, and lift the cuttings to
a cuttings basket above the core barrel for the smaller drills (Figure
2). The auger flights will eliminate, or at least minimize, the need for
fluid circulation for kerf-cuttings transport.

\(3\) Sonification, that is synergistic with the percussive core head
motion, is also used to "fluidize" the kerf cuttings on the auger
flights to reduce the friction between the bore wall and the auger.

\(4\) Low penetration rates and passive conductive heat dissipation are
used to keep the core temperature below 250K. When the required
penetration rate is so low that the core head's threshold WOB is not
achieved, intermittent coring at an efficient penetration rate and depth
of cut is used. Low power sonification and off-bottom rotation will be
maintained during the drill shut downs to preclude sticking.

These additions are intended to extend the hard rock core drilling
method to a low pressure CO~2~ atmosphere that almost certainly will
give rise to a very high mechanical friction between dry surfaces.
Unconsolidated sand or under-compacted crater ruble near the surface
will be penetrated and stabilized by auger drilling in a large diameter,
segmented, thin-walled drill rod casing with a rotary, impregnated
diamond core head. After each section of drill rod is drilled down, the
drill cuttings and the core, constrained in a thin-walled sleeve that
forms a core barrel and cuttings container, is removed and a new core
barrel/cuttings sleeve is installed. This is continued until all of the
largest diameter drill rods are drilled-in, the core head wears out, or
until the drill rods become stuck in a collapsed well bore. Then after
the last core barrel is removed, a core head guide sleeve (not shown) is
inserted where the core barrel was previously seated to guide and
stabilize the next coring assembly and provide the bore surface needed
for the auger to lift cuttings to the cuttings container. The gas
sampling and diverting head is removed, the top of any remaining drill
casing is cut off, the next smaller size drill coring assembly and
diverting head is installed, and the core head is drilled down from the
bottom of the last core retrieved. This second corehead and drill rod
casing is also left in place and a smaller diameter core is removed in
the same manner as its larger predecessor. This process is continued
until the smallest diameter core head wears out, becomes stuck, or is
advanced to the end of its drill rod string. The smallest core head is
designed to penetrate the hardest rock anticipated (low porosity basalt)
and is sized to cut and retrieve the smallest useful-sized sample.

The diamond kerfing bit is cooled by passive heat transfer to the Mars
environment, limiting the advance rate to keep the bit and sample
temperature below 250K. Downhole sensors are used to monitor the
drilling process and characterize the surrounding rock. We anticipate
reaching depths of 0.5 to 20m, depending on rock types encountered and
whether the drilling is from a fixed lander, a rover or
both.![](media/image2.jpeg){width="3.188888888888889in"
height="6.507638888888889in"}

Rock core samples and fine cuttings removed from the kerf area are
surface-logged to determine elemental composition and mineralogy, and
subsequently sub-sampled for further scientific analysis. Completed
holes are available for emplacement of seismometers or other
instruments; these are lowered into the hole with a wireline system.
Planetary protection (forward bio-contamination) is achieved by
eliminating any drilling fluid and using only inorganic drilling and
sampling materials compatible with high heat and chemical sterilization.
The concept is flexible in that it allows drilling a single relatively
deep hole from the fixed lander and/or multiple shallower holes from a
rover with periodic return of samples to the lander base and possible
resupply of drilling resources. The surface system is shown
schematically in the context of a generic lander in Figure 3. A
rover-mobilized version would have most of the same elements but would
only use a few segments of the smallest diameter drill string and a
reduced number of instruments.

## [Drilling approach]{.underline}![](media/image3.jpeg){width="3.5909722222222222in" height="4.626388888888889in"}

### *Comminution*

The highest efficiency method of breaking and comminuting rock is
combined mechanical rotary-percussion to induce tensile fracture and
large fragment sizes^\[1\].^ Small diameter holes and auger transport
will require small rock fragments that are produced at lower efficiency.
In our concept, we propose to produce the largest core possible to serve
as a large fragment. A high rotary speed, impregnated diamond crown bit
attached to a thin-walled metal tube or drill rod casing produces a
narrow circular kerf or slot in the rock, expending minimal energy to
penetrate a large variety of formations. The combination of high rotary
speed of the core head, the superimposed micro-percussion and modest
advance rates produce the small cutting fragments required and penetrate
with a low thrust and modest torque on the drill casing. This mode of
operation also tends to maintain a straight, vertical hole and reduces
the possibility of jamming the core barrel.

### *Cuttings removal*

In most terrestrial drilling, cuttings are removed by conveying them in
a fluid \-- water, air, foam or a viscous slurry called drilling mud. In
shallow civil engineering drilling, a rotary auger is often used to
mechanically ramp cuttings (or soil) to the surface. The depth to which
augers can be used is limited by the frictional resistance between the
rock and the auger flights, and so water is often added as a lubricant.
On Mars, the atmosphere might be used as a drilling fluid, but our
previous analysis^\[1\]^ suggests that the mass and power for
compressors and storage tanks exceed resources likely to be available on
early robotic missions. Hence, we propose to remove cuttings by
fluidless, dry augering, reducing friction by superimposing low
amplitude sonic/ultrasonic vibrations on helical auger flights on the
outside of the drill casing. Friction developed in the auger will be
limited by allowing the cuttings to fall into a cuttings container above
the core barrel so that the auger lift will not exceed 2-m.

### *Thermal analysis*

A finite difference thermal model of a diamond coring drill was used to
calculate the heating effects of drilling process energy, rate of
penetration, and bit configuration on the core produced for biologic and
geologic sampling. The drilling rates were determined which would result
in a maximum core temperature of 250 K, i.e., below ice melting with
some margin. An axisymmetric model accounts for conduction, convection,
and radiation between the drill, core, and formation. The drill
geometry, material properties, drilling process energy, and rate of
penetration can be varied to calculate the core and formation
temperatures. It is assumed that all of the energy required to break the
rock and any abrasion or friction energy is expended at the cutting
surface at the bottom of the bit, i.e., all of the kerfing process
energy is concentrated at this point.

## [Hole stability approach]{.underline}

Given the uncertainty of rock composition and structure in the
subsurface, consideration has to be given to hole stability. Without
such provision, hole collapse could easily lead to a stuck drill and an
inability to reach target depth or retrieve samples. In our concept, we
provide for hole stabilization by casing the hole as it is drilled. The
thin-walled drill string is left in place after a core segment is
removed. A new segment of drill string is then screwed on to the top of
the drilled-in segment and the hole deepened. After the maximum depth is
achieved for a particular drill string diameter (determined by torque,
weight on bit, bit wear or core recovery limitations) and the last
segment of core removed, the next smaller diameter bit and drill string
is lowered to the bottom of the cased hole and drilling is resumed. When
the drill rod becomes stuck before an entire joint is drilled down it
will be cutoff and set aside to allow operations with the next smaller
drill string to begin. This process is repeated until maximum depth is
reached. The end result is a completely cased hole with a stepped
diameter. Because casings are never tripped out using this approach, the
difficulty of cleaning the connections after exposure to Martian dust
and fine cuttings is minimized.

## 

## [Sampling approach]{.underline}

In our concept, subsurface samples consist of continuous core and
collected drill cuttings. Core and cuttings are retrieved in thin-walled
metal tubes that are longitudinally split to ease access or zippered or
cut in some yet to be determined fashion at the surface. The core
barrels and cuttings container are retrieved from downhole using a
wireline and placed in a location that is isolated from the rest of the
surface system. Provisions to prevent leakage of fine cuttings and soil
into the drill rod makeup and storage area will be required as the core
barrels are removed from the drill string. Once exposed at the surface
within the body of the surface system, core surfaces are logged
photographically and with specific instruments such as the LIBS-Raman
probe. Pieces of the core and cuttings are subsampled and introduced to
other science instruments that are part of the surface system. Unused
portions of the cores and cuttings can either be ejected to the surface
for disposal or archived within the surface system for later retrieval.

## [Control system]{.underline}

The downhole drilling and sampling system will be instrumented to
monitor bit temperature, torque and thrust (WOB) at the core head and
transmitted up the drill string with acoustic telemetry. Downhole power
will be generated from the percussive motion of the drill string. These
plus other process variables measured at the surface such as advance
(rate), rotary speed, percussion amplitude and frequency, and motor
current will be used to assess and control the system. Control
algorithms will be developed to continuously monitor the drilling
process, sense off-nominal conditions and automatically retreat to a
safe condition to await analysis and intervention from Earth. Under
nominal conditions, the drilling, coring and sample processing will be
completely autonomous.

## [Science measurements]{.underline}

Scientific measurements while drilling will be limited to continuous
uphole collection of gases generated or exposed by the drilling process.
These gases will be introduced to surface system instruments such as gas
chromatograph-mass spectrometer or other yet to be determined sensors.
Downhhole sensors such as fiberoptic chemical detectors are also
possible but not yet developed to a high TRL. A surface seismometer
array can be deployed around the rig to produce an acoustic log (reverse
vertical seismic profile) using the (micro-percussive plus rotary)
kerfing noise as a source. After drilling and core retrieval with a
specific drill string diameter is completed, instruments will be run
into the cased hole by wireline, and measurements of surrounding rock
made using techniques compatible with through-casing logging. These
might include neutron/gamma rock density/porosity; through-casing
electromagnetic measurements may also be possible. Scientific
measurements on recovered core and cuttings samples would include a
range of petrophysical, geological and biological variables not
discussed here.

## [Mobility]{.underline}

Our concept is primarily based on achieving the deep sampling from a
single location, the lander, within the mass, power and other
constraints. The approach is flexible enough that it could also be
mobilized from a rover, but additional operational constraints would
limit the depth and size of samples.

# **Parametric analysis**

## [Introduction]{.underline}

To obtain some quantitative predictions to test against the assumed
cases, we adapted an analytic rotary diamond bit model from the
literature and used what rock mechanics data we could find for some
relevant rock types. The bit model is the core of a more comprehensive
Mars drilling engineering model that we are building. The bit sub-model
parameterizes a rotary diamond kerfing bit of the type we assume in our
concept. The model does not presently include the micropercussion we
would like to use, so we take no credit for any enhancement of
penetration due to the percussion. In this sense, the current model
version is conservative and only relies on the sonification to help
remove cuttings. The larger model does include a simple auger sub-model
to estimate friction forces and power needed to remove cuttings.
Short-column buckling and traditional casing buckling loads have been
calculated to assure that the WOB required can be applied without
inducing instability to the drill casing string. The integrated model
will also include the thermal sub-model we describe above.

The diamond cutter sub-model we used was developed by F. C. Appl and D.
S. Rowley^\[2\]^, and is based on a rigid, plastic, Coulomb material,
and Mohr's combined stress theory using a simplified Mohr envelop
relation and a Coulomb failure criterion. The diamonds are assumed to be
spherical and the depth of cut is calculated based on a spherical
depression in the rock. The required inputs for the model include: (1)
the unconfined compressive strength and Coulomb-Mohr parameters for
rock, (2) the coefficient of friction between the diamond and the rock,
(3) the angle between the cutting surface and the rock chips at the
leading edge of the cutter, and (4) the radius of the diamond cutters.
We have doubled the assumed friction between the cutter and the rock to
simulate shallow air or fluidless drilling. The shear and normal forces
on the diamond are output as a function of the depth of cut (impression
depth). The surface-set diamond bit sub-model^\[3\]^, combines the
diamond cutter sub-model with a simplified, one-dimensional bit
description where all bit parameters can be defined as functions of the
bit radius but are independent of the bit tangential and axial
dimensions. Bit parameters include the fraction of cutting pads to total
area, the cutter density per unit area, the angle of the cutting surface
to the bit axis. Weight-on-bit and torque are calculated as a function
of rotary speed and penetration rate which define the depth of cut per
rotation. A vector summation of the normal and shear forces on each
diamond is resolved into components parallel to the bit axis and the
tangential vector. No provision for a radial component on the bit is
considered in this simple model. It also assumes perfect hole cleaning
at the cutting surface with a massless, frictionless drilling fluid. It
does not have any provision for diamond wear. This bit sub-model
predicts experimental drilling rates within [+]{.underline}25% in
Georgia Granite and Beekmantown Dolomite, drilling with water or mud
when it is assumed that 100% of the cutters are in contact with the
rock. Assuming 80% contact tends to predict the maximum penetration
rate. A coefficient of friction between wet diamond and wet rock of 0.05
is assumed to produce these results. Calculated process (specific)
energy values using the model for granites and dolomites range from 0.2
to 0.6 GJ/m^3^. The published drilling data shows that the model
reproduces bit weight accurately but the drilling torque values were
unavailable so torque and process energy are not verified in the
publication describing the models. We have not found a coefficient of
friction for dry diamond on dry rock at any temperature and have used a
value of 0.1 until better values are available at Mars-relevant
conditions. This combined with the addition of the micropecussion to the
rotary motion is believed to be a conservative estimate.

We have constructed a "perspective drilling variable map" in Figure 4.
The drilling process variables are organized to illustrate the analysis
that has to be performed to produce feasibility and performance
predictions. The outermost ring defines independent variables and
top-level process variables that are largely determined by the mission
constraints. As we move inward in the figure, additional process
variables are defined, sometimes playing the roles of independent
variables and sometimes as dependent variables in the calculations. In
the center is the primary dependent variable, depth of penetration. We
haven't tried to show all of the complex interactions between variables
that constitute the physics of the processes, but hope that the figure
makes the point that any optimization of the process will be complex,
and validation will require a significant amount of experimental data at
relevant Mars environmental conditions. Such data presently do not
exist. One could also think of the figure as a systems analysis or trade
studies map. We believe the larger point to be made is that, to be
credible, any mechanical drilling process and its semiautonomous control
system will have to be designed based on numerous cause and effect
relationships between each of the variables shown. The picture we are
presenting should also caution us all that, at this point in its
development, any Mars drilling feasibility claims inherently include a
large number of unknowns and unverified assumptions.

## [Results]{.underline}

Table 1 lists the rock mechanics properties for two of the rock types we
assumed and for which we could find data.

![](media/image4.jpeg){width="4.8in" height="4.727777777777778in"}

+-----------+----------+----------+-----------+-----------+-----------+
| # **Ta    |          |          |           |           |           |
| ble 1: Pr |          |          |           |           |           |
| operties  |          |          |           |           |           |
| and Coulo |          |          |           |           |           |
| mb-Mohr P |          |          |           |           |           |
| arameters |          |          |           |           |           |
|  for Assu |          |          |           |           |           |
| med Targe |          |          |           |           |           |
| t Rocks** |          |          |           |           |           |
+-----------+----------+----------+-----------+-----------+-----------+
|           |          |          |           |           |           |
+-----------+----------+----------+-----------+-----------+-----------+
| ## **Ro   | **Un     | **Angle  | **Mohr    |           |           |
| ck Type** | confined | of       | Envelop   |           |           |
|           | Com      | Internal | Ex        |           |           |
|           | pressive | Fr       | ponential |           |           |
|           | St       | iction** | Appr      |           |           |
|           | rength** |          | oximation |           |           |
|           |          | *        | Par       |           |           |
|           | *        | *(deg)** | ameters** |           |           |
|           | *(MPa)** |          |           |           |           |
+-----------+----------+----------+-----------+-----------+-----------+
|           |          |          | **Shear   | **b-pa    | **ψ-pa    |
|           |          |          | Stress,   | rameter** | rameter** |
|           |          |          | τ~ ∞~**   |           |           |
|           |          |          |           | **(MPa)** | **(M      |
|           |          |          | **(MPa)** |           | pa^-1^)** |
+-----------+----------+----------+-----------+-----------+-----------+
| ### Mioce | **290**  | **45**   | **550**   | **480**   | *         |
| ne Basalt |          |          |           |           | *0.0023** |
+-----------+----------+----------+-----------+-----------+-----------+
| **Berea   | **47**   | **38**   | **210**   | **200**   | *         |
| Sa        |          |          |           |           | *0.0038** |
| ndstone** |          |          |           |           |           |
+-----------+----------+----------+-----------+-----------+-----------+

The Coulomb-Mohr parameters represent fits of triaxial failure data to
an equation of the form τ = τ~ ∞~−be^−ψσ^ where τ and σ are
corresponding shear and normal stress values, respectively, and τ~ ∞~, b
and ψ are constants for a particular rock type.

Table 2 lists the dimensions and estimated masses of downhole drilling
components that were either assumed initially or the result of iterative
calculations.

+----------------+---------+---------+---------+---------+---------+
| ## **Table 2:  |         |         |         |         |         |
|  Prototype Dim |         |         |         |         |         |
| ensions and Es |         |         |         |         |         |
| timated Mass** |         |         |         |         |         |
|                |         |         |         |         |         |
| ## **Sha       |         |         |         |         |         |
| llow Drilling  |         |         |         |         |         |
| System Downhol |         |         |         |         |         |
| e Components** |         |         |         |         |         |
+----------------+---------+---------+---------+---------+---------+
| **D            | **      | **2^nd^ | **1^st^ | **Su    | **Cond  |
| rilling/Casing | Final** | Interme | Interme | rface** | uctor** |
| Sections**     |         | diate** | diate** |         |         |
|                | **C     |         |         | **C     | **C     |
|                | asing** | **C     | **C     | asing** | asing** |
|                |         | asing** | asing** |         |         |
+----------------+---------+---------+---------+---------+---------+
| ##             | **Aus   |         |         |         |         |
|  **Core Head** | tenitic |         |         |         |         |
|                | St      |         |         |         |         |
|                | ainless |         |         |         |         |
|                | Steel   |         |         |         |         |
|                | Body**  |         |         |         |         |
+----------------+---------+---------+---------+---------+---------+
| **Hole         | **15**  | *       | *       | *       | **82**  |
| Diameter       |         | *23.3** | *35.6** | *54.2** |         |
| (mm)**         |         |         |         |         |         |
+----------------+---------+---------+---------+---------+---------+
| **Core         | **10**  | *       | *       | *       | *       |
| Diameter       |         | *15.5** | *23.8** | *36.1** | *54.7** |
| (mm)**         |         |         |         |         |         |
+----------------+---------+---------+---------+---------+---------+
| **Axial length | **5.0** | **7.8** | *       | *       | *       |
| (mm)**         |         |         | *11.9** | *18.1** | *27.3** |
+----------------+---------+---------+---------+---------+---------+
| ##             | **      | **      | **      | **      | **      |
|  **Mass (kg)** | 0.004** | 0.014** | 0.052** | 0.183** | 0.633** |
+----------------+---------+---------+---------+---------+---------+
| ## **Dril      | **A     |         |         |         |         |
| l Rod Casing** | luminum |         |         |         |         |
|                | Casing  |         |         |         |         |
|                | with    |         |         |         |         |
|                | E       |         |         |         |         |
|                | xternal |         |         |         |         |
|                | Auger   |         |         |         |         |
|                | Fl      |         |         |         |         |
|                | ights** |         |         |         |         |
+----------------+---------+---------+---------+---------+---------+
| **OD (mm)**    | *       | *       | *       | *       | *       |
|                | *14.3** | *21.5** | *32.3** | *48.5** | *72.8** |
+----------------+---------+---------+---------+---------+---------+
| **ID (mm)**    | *       | *       | *       | *       | *       |
|                | *12.0** | *18.0** | *27.0** | *40.5** | *60.7** |
+----------------+---------+---------+---------+---------+---------+
| **Axial length | **      | **      | **      | **      | **      |
| (mm)**         | 500.0** | 500.0** | 500.0** | 500.0** | 500.0** |
+----------------+---------+---------+---------+---------+---------+
| #### Numb      | **51**  | **33**  | **19**  | **9**   | **3**   |
| er of Sections |         |         |         |         |         |
+----------------+---------+---------+---------+---------+---------+
| ##             | **3.5** | **5.1** | **6.7** | **7.1** | **5.3** |
|  **Mass (kg)** |         |         |         |         |         |
+----------------+---------+---------+---------+---------+---------+
| ## **Core Ba   | **T     |         |         |         |         |
| rrel Sleeves** | itanium |         |         |         |         |
|                | T       |         |         |         |         |
|                | ubing** |         |         |         |         |
+----------------+---------+---------+---------+---------+---------+
| **OD (mm)**    | *       | *       | *       | *       | *       |
|                | *11.5** | *17.5** | *26.5** | *40.0** | *60.2** |
+----------------+---------+---------+---------+---------+---------+
| **ID (mm)**    | *       | *       | *       | *       | *       |
|                | *10.5** | *16.0** | *24.3** | *36.6** | *55.2** |
+----------------+---------+---------+---------+---------+---------+
| **Axial length | **      | **      | **      | **      | **      |
| (mm)**         | 500.0** | 500.0** | 500.0** | 500.0** | 500.0** |
+----------------+---------+---------+---------+---------+---------+
| #### Numb      | **18**  | **8**   | **6**   | **4**   | **2**   |
| er of Sections |         |         |         |         |         |
+----------------+---------+---------+---------+---------+---------+
| **Mass (kg)**  | *       | *       | **1.3** | **1.9** | **2.2** |
|                | *0.72** | *0.74** |         |         |         |
+----------------+---------+---------+---------+---------+---------+

Drilling system performance predicted for our concept is summarized in
Table 3 for an assumed worst case rock, basalt, and an intermediate
strength rock, sandstone, and a range of

+----------------+---------+---------+---------+---------+---------+
| ## **Ta        |         |         |         |         |         |
| ble 3: Calcula |         |         |         |         |         |
| ted Performanc |         |         |         |         |         |
| e Parameters** |         |         |         |         |         |
|                |         |         |         |         |         |
| ## **Do        |         |         |         |         |         |
| wnhole Prototy |         |         |         |         |         |
| pe Shallow Dri |         |         |         |         |         |
| lling System** |         |         |         |         |         |
+----------------+---------+---------+---------+---------+---------+
| **D            | #####   | **2^nd^ | **1^st^ | **Su    | **Cond  |
| rilling/Casing | # Final | Interme | Interme | rface** | uctor** |
| Sections**     |         | diate** | diate** |         |         |
|                | **C     |         |         | **C     | **C     |
|                | asing** | **C     | **C     | asing** | asing** |
|                |         | asing** | asing** |         |         |
+----------------+---------+---------+---------+---------+---------+
| # *            |         |         |         |         |         |
| *Calculated St |         |         |         |         |         |
| rength of Dril |         |         |         |         |         |
| l Rod Casing** |         |         |         |         |         |
|                |         |         |         |         |         |
| ## **(assum    |         |         |         |         |         |
| e connections  |         |         |         |         |         |
| have 50% of pi |         |         |         |         |         |
| pe strength an |         |         |         |         |         |
| d no other saf |         |         |         |         |         |
| ety factors)** |         |         |         |         |         |
+----------------+---------+---------+---------+---------+---------+
| #### Max. Ten  | *       | *       | **      | **      | **      |
| sion (kg-g~M~) | *3350** | *7560** | 17000** | 38400** | 86400** |
+----------------+---------+---------+---------+---------+---------+
| **Max. Torsion | *       | **128** | **433** | *       | *       |
| (N-m)**        | *37.8** |         |         | *1460** | *4650** |
+----------------+---------+---------+---------+---------+---------+
| ## **          |         |         |         |         |         |
| Core Head -- A |         |         |         |         |         |
| ssumed Drillin |         |         |         |         |         |
| g Parameters** |         |         |         |         |         |
+----------------+---------+---------+---------+---------+---------+
| **Rotary Speed | *       | *       | **250** | **50**  | **10**  |
| (rpm)**        | *5000** | *1250** |         |         |         |
+----------------+---------+---------+---------+---------+---------+
| *              | **6.2** | **3.1** | **1.5** | **0.8** | **0.4** |
| *Instantaneous |         |         |         |         |         |
| (m/sol)**      |         |         |         |         |         |
+----------------+---------+---------+---------+---------+---------+
| #####          |         |         |         |         |         |
+----------------+---------+---------+---------+---------+---------+
| ## **Mio       | #       |         |         |         |         |
| cene Basalt**  | #### Pe |         |         |         |         |
|                | rforman |         |         |         |         |
|                | ce Data |         |         |         |         |
+----------------+---------+---------+---------+---------+---------+
| ###            |         |         |         |         |         |
| Core Head - Ca |         |         |         |         |         |
| lculated Drill |         |         |         |         |         |
| ing Parameters |         |         |         |         |         |
+----------------+---------+---------+---------+---------+---------+
| ## **Weight on | **6.6** | *       | **60**  | **190** | **610** |
|  Bit (kg-gm)** |         | *18.7** |         |         |         |
+----------------+---------+---------+---------+---------+---------+
| ## **          | *       | *       | *       | **3.7** | *       |
| Torque (N-m)** | *0.03** | *0.13** | *0.70** |         | *19.3** |
+----------------+---------+---------+---------+---------+---------+
| **Power (W)**  | *       | *       | *       | *       | *       |
|                | *15.1** | *17.2** | *18.3** | *19.3** | *20.2** |
+----------------+---------+---------+---------+---------+---------+
| #              | **2.2** | **2.1** | **1.9** | **1.7** | **1.6** |
| ### Process En |         |         |         |         |         |
| ergy (GJ/m^3^) |         |         |         |         |         |
+----------------+---------+---------+---------+---------+---------+
| #### Critical  |         |         |         |         |         |
|  Buckling Load |         |         |         |         |         |
+----------------+---------+---------+---------+---------+---------+
| #### Sh        | **65**  | **22**  | **7**   | **\<2** | **\<1** |
| ort Column (%) |         |         |         |         |         |
+----------------+---------+---------+---------+---------+---------+
| #### B         | **34**  | **29**  | **29**  | **28**  | **26**  |
| ore supported  |         |         |         |         |         |
| drill stem (%) |         |         |         |         |         |
+----------------+---------+---------+---------+---------+---------+
| **Top of Drill |         |         |         |         |         |
| Casing -       |         |         |         |         |         |
| Calculated     |         |         |         |         |         |
| Drill Rod      |         |         |         |         |         |
| Performance**  |         |         |         |         |         |
+----------------+---------+---------+---------+---------+---------+
| ## **          | *       | *       | *       | **3.7** | *       |
| Torque (N-m)** | *0.05** | *0.16** | *0.72** |         | *19.3** |
+----------------+---------+---------+---------+---------+---------+
| **Power (W)**  | *       | *       | *       | *       | *       |
|                | *28.5** | *20.4** | *18.8** | *19.4** | *20.2** |
+----------------+---------+---------+---------+---------+---------+
| #              | **4.2** | **2.4** | **2.0** | **1.7** | **1.6** |
| ### Process En |         |         |         |         |         |
| ergy (GJ/m^3^) |         |         |         |         |         |
+----------------+---------+---------+---------+---------+---------+
|                |         |         |         |         |         |
+----------------+---------+---------+---------+---------+---------+
| ## **Bere      | ###     |         |         |         |         |
| a Sandstone**  | #### Pe |         |         |         |         |
|                | rforman |         |         |         |         |
|                | ce Data |         |         |         |         |
+----------------+---------+---------+---------+---------+---------+
| **Core Head -  |         |         |         |         |         |
| Calculated     |         |         |         |         |         |
| Drilling       |         |         |         |         |         |
| Parameters**   |         |         |         |         |         |
+----------------+---------+---------+---------+---------+---------+
| ## **Weight on | **1.4** | **4.0** | **13**  | **41**  | **130** |
|  Bit (kg-gm)** |         |         |         |         |         |
+----------------+---------+---------+---------+---------+---------+
| ## **          | **0.6** | **2.8** | **15**  | **78**  | **410** |
| Torque (N-m)** |         |         |         |         |         |
+----------------+---------+---------+---------+---------+---------+
| **Power (W)**  | **3.2** | **3.7** | **3.9** | **4.1** | **4.3** |
+----------------+---------+---------+---------+---------+---------+
| #              | *       | *       | *       | *       | *       |
| ### Process En | *0.47** | *0.45** | *0.40** | *0.37** | *0.34** |
| ergy (GJ/m^3^) |         |         |         |         |         |
+----------------+---------+---------+---------+---------+---------+
| #### Critical  |         |         |         |         |         |
|  Buckling Load |         |         |         |         |         |
+----------------+---------+---------+---------+---------+---------+
| #### Sh        | **14**  | **4.6** | **1.5** | **\<1** | **\<1** |
| ort Column (%) |         |         |         |         |         |
+----------------+---------+---------+---------+---------+---------+
| #### B         | **7.2** | **6.2** | **6.1** | **5.8** | **5.5** |
| ore supported  |         |         |         |         |         |
| drill stem (%) |         |         |         |         |         |
+----------------+---------+---------+---------+---------+---------+
| **Top of Drill |         |         |         |         |         |
| Casing -       |         |         |         |         |         |
| Calculated     |         |         |         |         |         |
| Drill Rod      |         |         |         |         |         |
| Performance**  |         |         |         |         |         |
+----------------+---------+---------+---------+---------+---------+
| ## **          | **3.2** | **5.2** | **17**  | **79**  | **410** |
| Torque (N-m)** |         |         |         |         |         |
+----------------+---------+---------+---------+---------+---------+
| **Power (W)**  | **17**  | **6.9** | **4.4** | **4.2** | **4.2** |
+----------------+---------+---------+---------+---------+---------+
| #              | **2.4** | *       | *       | *       | *       |
| ### Process En |         | *0.84** | *0.46** | *0.37** | *0.34** |
| ergy (GJ/m^3^) |         |         |         |         |         |
+----------------+---------+---------+---------+---------+---------+

process variables appropriate for the given mission constraints. Power
is the continuous power needed to sustain the assumed rotary speed and
instantaneous advance rate. The effective advance rate is controlled by
heat build-up during drilling which, in turn, is controlled by rock
thermal properties and drilling process energy. Frictional heating and
rock deformation cause the sample to heat rapidly in most cases. To
control the sample heating below a value (250K) to avoid ice melting and
heat-induced bore instability, an on-off strategy is used in which the
rock is repeatedly drilled for a short period of time and then allowed
to cool. The average or effective advance rate can then be calculated by
integrating over the on-off cycles. Results from the thermal sub-model
shown in Figures 5-7 illustrate these points. Figure 5 shows some of the
detail in drilling start-up in basalt for a 15-mm core head and a
6-m/Sol instantaneous drill rate. Drilling starts with the rock
temperature assumed to be uniform at 200K. The maximum rock core
temperature near the bit edge (red curve) is calculated assuming 100% of
the mechanical energy at the core head is converted to heat in the
neighboring rock and core. We assume that the heat contained in the kerf
cuttings is rapidly transported away form the core head.

The calculated temperature increases quickly until a value of 250K is
reached. At this point drilling is stopped and the rock allowed to cool
down to some lower value at which drilling is resumed and another on-off
cycle produced. The two panels in the figure show the effects of two
different lower cooling temperature points. The green line shows the
periodic advance of the drill and the blue line shows the integrated or
"effective" drilling rate. Figure 6 shows another case for basalt with a
23.3-mm core head and instantaneous 3-m/Sol drill
rate.![](media/image5.jpeg){width="4.7027777777777775in"
height="3.2680555555555557in"}![](media/image6.jpeg){width="4.095833333333333in"
height="4.200694444444444in"}

A full 8 hour drilling cycle is shown in this calculation, appropriate
to Case 1 mission assumptions. Notice that the effective drilling rate
settles down to a near-constant value and a total of about one half
meter is drilled over the 8 hour period for these particular model
assumptions. Figure 7 shows the effects of rock type. The red curve in
this figure represents the drilling time fraction or duty cycle of the
on-off process. For basalt, about one half meter was drilled in 8 hours
with a duty cycle approaching 50%. However for sandstone, the lower
kerfing energy allows continuous drilling to a depth of one meter in the
same time period. Continuous drilling is also possible in basalt for
some combinations of bit diameter and instantaneous drill rate. The
results of a limited parameter study for basalt and sandstone are
summarized in Table 4.

Figure 8 shows one way in which heating could be reduced through bit
design. Reducing the number of diamonds in contact with the rock at a
given radius will reduce the energy expended in creating the kerf. This
can not be taken too far, however, without reducing bit performance and
reliability. Our results suggest that perhaps 10-20% less heating could
be achieved in this way relative to assumptions of the present
conceptual point design; this approach and others would be part of the
system optimization.

Figure 9 shows the strong effects of rock type and coefficient of
friction on the calculated kerfing energy, which, in turn, determines
sample heating. Clearly, much experimental data is needed to constrain
these design parameters.

Finally, all of the parametric design calculations we have performed to
date are summarized in Table 4. In the table we have also made estimates
of power and mass for surface system components and summed these with
the drilling system mass to produce a total system cumulatively for each
casing diameter. Thus, each column includes those to its left.

![](media/image7.png){width="4.133333333333334in"
height="4.672916666666667in"}

## [Mars 2007 Mission Feasibility]{.underline}

**[*The analysis shows that all four cases can be achieved with drilling
and sampling to a depth of 20m using the smallest three drill casing
diameters*.]{.mark}** The mass constraint for Case 4 is significantly
violated if four casing diameters need to be used and mass constraints
are such that only Case 3 can be met to a depth of 20 m if all five
casing diameters are needed. If additional time for drilling is allowed,
even greater depths look to be theoretically possible, although other
factors such as hole deviation could limit these possibilities and we
need to be cautious in making any such claims. Actual performance will
depend critically on the rock variability encountered as well as many
other factors.

# **Lander and Operations Impacts**

A 50kg mass limit (Case 4) constrains us to use only the three smallest
strings, thereby increasing risk. If 100kg can be provided, we then
approach the power limits. Clearly, Cases 2 and 3 provide sufficient
power and mass to reach 20m with significant margin and
flexibility.![](media/image8.png){width="4.598611111111111in"
height="3.5006944444444446in"}

# **Technology development plan and schedule**

The analysis behind our conceptual design is based on data for and
experience with terrestrial drilling systems that use drilling fluids
and ambient terrestrial environmental conditions. As far as we know,
there are no data for any kind of drilling system under conditions of
Mars temperature and pressure. Therefore, extrapolation of terrestrial
experience and models could be in significant error. To reduce the
technology risk associated with this lack of data, it is very important
to develop, as soon as possible, a small scale laboratory testbed with
which to acquire fundamental rock physics and drilling mechanics data
and experience at simulated Mars conditions. This preliminary work is
essential to guide realistic design of Mars drilling systems. This task
is an early component of a technology development plan that we propose
below, leading to PDR for a 2007
mission.![](media/image9.pct){width="3.0305555555555554in"
height="3.5993055555555555in"}

## **Technology Development Plan and Schedule**

![](media/image10.pct){width="6.603472222222222in"
height="1.726388888888889in"}

**Task 1 -- Mission Definition**. Subsurface steering team meets with
MEPAG and program managers to define 2007 mission subsurface exploration
objectives and constraints (mass, power etc.). Based on these
discussions, a mission is defined and subsurface sampling requirements
specified against which prototype subsurface drilling and sampling
technologies will be developed.

**Task 2 -- Comminution & Cuttings Testbed Design & Fab**. A bench-scale
Mars environment testbed is designed and fabricated. Test volume is
approximately 0.5 m^3^, temperature 200K, pressure \<600 Pa.
Instrumented for bottom hole assembly testing and drilling physics data
collection.

**Task 3 -- Bench-Scale Bit & BHA testing**. The C&C testbed developed
in Task 2 is used to investigate mechanics of rock comminution, cuttings
transport and hole stabilization under simulated Mars conditions of
temperature and pressure. Bit designs, cuttings removal approaches and
aspects of hole stabilization are investigated in a user facility mode
of operation.

**Task 4 - Subsystem Design, Fab & Testing -- Technology Competition**.
Subsystems of technologies from several sources are selected for design,
fabrication and testing. Concurrently with Tasks 2 and 3, proposals will
be solicited for the modification of mature terrestrial drilling
technologies with innovative but appropriate modifications to adapt the
systems for the unique Martian surface and near-surface environment.
Selection criteria will be used to limit the number of proposals that
will be considered. These criteria will be developed by the Subsurface
steering team to select technologies judged most likely to meet mission
objectives and constraints. Testing is performed in numerous terrestrial
sites and environments to down select systems for redesign and testing
in the system-scale testbed developed under Task 6 and bench-scale
testbed developed under Task 2, as appropriate. All subsystems,
including BHA deployment, thermal management and automated control are
developed and tested.

**Task 5 -- Prototype Systems Analysis & Technology Down-selection**.
Using the results from Tasks 1-5, an engineering systems analysis is
performed to compare and select the best technologies from which a
prototype system will be identified for further development.

![](media/image11.pct){width="5.990972222222222in"
height="7.550694444444445in"}

**Task 6 -- System-Scale Prototype Testbed Design & Fab**. A larger
testbed is designed and fabricated for full-scale system testing
installed in an existing facility. Competitive pre-prototype subsystems
and full systems are tested under simulated Mars temperatures and
pressures (\~200 K, \~600 Pa). Down-selected prototype systems will also
be tested in this facility. A cylindrical test volume approximately 2
m-diameter by 5 m-long is anticipated.

**Task 7 -- Prototype system fabrication**. Based on the systems
analysis of Task 5, one or more prototype systems are developed for
testing.

**Task 8 -- Full-Scale Prototype Testing**. One or more prototype
systems are tested under simulated Mars conditions in the full-scale
testbed developed under Task 6. Engineering data sets are developed.

**Task 9 -- Preliminary Flight System Design**. Results of Tasks 1-8 are
used as the basis for a preliminary flight system design.

**Task 10 -- PDR**. Preliminary design review is performed.

# **References**

\[1\] Blacic, J.D., D.S. Dreesen and T. Mockler, "Report on conceptual
systems analysis of drilling systems for 200-m-depth penetration and
samplin of the Martian subsurface", Los Alamos Nat. Lab. Rpt.
#LAUR00-4742, 86pp.,October, 2000.

\[2\] Appl, F. C. and D. S. Rowley, "Analysis of the cutting action of a
single diamond", SPE Jour., SPE paper #2316, 269-280, 1968.

\[3\] Rowley, D. S. and F. C. Appl, "Analysis of Surface Set Diamond Bit
Performance," SPE paper No. 2242, SPE Journal, 301-310Sept. 1969.

# 

# **Estimated cost**

TRL Level 6 system for robotic test in Mars environment chamber three
years from now: \$10-20M.

**APPENDIX C**

**DRILLING WHITE PAPER**

**FROM**

**JSC/BAKER HUGHES**

MARS DRILLING CAPABILITY BRIEFING PAPER

JPL/JSC/BAKER HUGHES DRILL DESIGN

\[Based on the 1999 Work of Team X\]

NASA JOHNSON SPACE CENTER

NASA JET PROPULSION LABORATORY

BAKER HUGHES

Compiled by:

Humboldt C. Mandell, Jr., Ph.D.

NASA JSC Exploration Office

March 14, 2001

**[MARS DRILLING CAPABILITY BRIEFING PAPER]{.underline}**

[RECOMMENDATIONS FOR A MARS DRILLING SYSTEM:]{.underline}

[Foreword:]{.underline}

If liquid water lies below the Mars surface, the technology exists to
find it, and to do so by 2009, at low cost and risk.

In the process of planning an integrated human and robotic program for
the exploration of Mars, the scientific community has often touted the
advantages of drilling deeply into the Martian surface. The HEDS
community has also established Mars drilling as an important objective.
Both communities share a common desire: to find water, and to do so as
early as possible! This objective probably demands drilling depths
greater than 200 meters.

During the Fall of 1999, NASA JPL, JSC and the commercial drilling firm
of Baker Hughes conducted an intensive study to determine the
feasibility of a 200 meter Mars drill, to be the prototype and
technology demonstrator for a 3-4 kilometer drill deployed on a
subsequent mission.

In summary, a proprietary design presented by Baker Hughes satisfied all
mission requirements for performance, cost, mass, development schedule,
and risk. It would reach 200 meters in depth in less than one Earth year
of operations. It satisfied the NASA team that the concept, which uses
proven technologies, would provide a very low risk mission, capable of
producing enormously significant scientific and engineering returns at
very reasonable cost.

The design concept proposed by Baker Hughes is scalable to wide range of
masses and power requirements, as specified by the Case constraints of
this study, while retaining the advantages of technological readiness of
the basic design.

JSC realizes that current JPL planning constraints are not encouraging
for advocates of an early program to find water in the Martian
subsurface. However, it is our hope that by emphasizing the technical,
cost, and schedule feasibility of reaching significant depths on early
missions, those planning the next generation of Mars missions will
recognize the scientific and human exploration technology windfall which
is within our grasp.

[Summary]{.underline}:

Preliminary analysis has been performed to weigh the basic Baker-Hughes
200 meter drill design against the more stringent January 2001 JPL
requirements (4 cases). The design *concept* can meet all of the case
constraints, and do so at low cost and risk. However, to achieve the 100
kg mass limit, the design would no longer be identical to that of the
3-4 kilometer drill, but rather a scaled version for that one mission
only. Most key technologies could be demonstrated, however. At the 50 kg
mass limit, most hardware commonality would probably be lost, but some
critical technologies (like automation, sampling, and cuttings removal)
would still be demonstrated.

The basic design *concept* will satisfy all four of the JPL Cases, and
reach a minimum of 20 meters for each case (See Table 1). For any given
drill design, the mass of the hole stabilization devices, core storage
facility, and drill cable are the primary variables. The mass of the
baseline drill with 20 meters of depth capability is 154 kg (very close
to Case 3).

TABLE 1

[Autonomy]{.underline}:

An area NOT addressed in the JPL comparative criteria is the automation
of the drill. This is a significant omission.

Baker Hughes is the world leader in drill automation, and has
successfully demonstrated fully automated drilling in very
environmentally-hostile Earth applications. This is a major, and perhaps
enabling advantage for this mission, in that the autonomy protocols have
already been developed, and the software proven in a number of projects.

The following sections address each of the JPL comparative criteria in
more detail.

[Depth:]{.underline}

The JPL/JSC/Baker Hughes drill concept is capable of drilling to 200
meters with a mass of 231 kg. At the JPL-defined mass levels (Cases
1-4), depths of approximately 20-35 meters would be the limit of
capability. The drill requires redesign to meet the 50 or 100 kg mass
limits, but the design is scalable to those sizes. When the design is
re-optimized to meet the mass limits of the JPL Cases, depths up to 35
meters may be achievable for Cases 1-3. At the lower mass limits, the
major advantage of providing an engineering testbed for the 3-4
kilometer drill would be compromised, along with the major scientific
gains of the 200 meter depth. This could result in the requirement for
an additional mission to verify the deep drill design prior to its
deployment.

[Sampling:]{.underline}

One of the great virtues of this design is that it is a dry coring
drill. Intact, *protected,* sample cores of 25 mm (one inch) diameter by
1 meter in length are the design capability. These samples would not be
contaminated by the presence of drilling fluids. Industry standard
coring techniques are used to achieve these results, and the technology
is proven. Highly sophisticated, multi-spectral in-situ measurements may
be made as the bit penetrates the Martian subsurface, and additional
analyses may be performed on the cores at the surface.

Cuttings (fully correlated with the intact cores) are also retrieved,
and would be useful for analyses requiring a granular or powdered
sample. Contamination is avoided by solid coring sleeves which fully
contain the samples. There is no provision in the current design for
preserving down-hole temperatures, and the cost versus benefits of
providing this capability should be explored prior to making this a
design requirement.

It is expected that the design will keep ice samples frozen, because of
the low drilling energies employed, and the low ambient Mars
temperatures. The bottom hole assembly (BHA) contains instrumentation
which allows the temperature at the drill face to be adjusted by
changing the weight on bit, another feature not available with some
competing concepts.

The sampling process involves deploying a mechanical, electric motor
driven, coring BHA on a multi-function cable. The assembly is stabilized
by devices which contact and put pressure on the sides of the hole,
while a tractor device within the BHA advances the drill head. \[Details
of the design are proprietary to Baker Hughes, and can be provided
separately.\] Hole stability is preserved by a proven, proprietary Baker
Hughes process. Samples are retrieved after each one-meter drilling duty
cycle, expected to take one sol (200 meter design requirement, and Case
3).

As the cores are brought to the surface, they are ejected (intact) into
a collection magazine mechanism, which stores all cores (if all are
needed) for further analysis (or potential return to earth on later
missions).

At the original design power level, the drill advances approximately one
meter per day. Case 1, 2, and 4 power levels would require
proportionally longer drilling times. In Cases 1, 2, and 4, power
available would enable the drill to reach greater than 20 meters depth
in the available operational lives, but the drill is constrained by mass
from reaching much greater depths. In Case 3, the drill could
hypothetically reach a depth of 650 meters within the power and time
requirements, but is mass limited to shallower depths. (Figure 1,
below).

[FIGURE ONE]{.underline}

![](media/image12.png){width="5.520138888888889in"
height="4.211805555555555in"}

[Downhole science:]{.underline}

The drill design incorporates a suite of downhole sensors. A major
virtue of the BHI design is that it enables a data cable to be deployed
between the surface and the BHA, capable of transmitting high data rates
from in-situ sensors directly to Earth via the spacecraft communications
system. Data can also be analyzed in-situ to reduce the required
bandwidth to Earth. The design also enables suites of downhole sensors
to be deployed on a "wire line" independently from the BHA.

Baker Hughes is a world leader in the development of state-of-the-art
downhole sampling devices. Their proprietary technologies include
breakthroughs in both size and capability of the sensors. The design of
down-hole and surface instrumentation is outside the scope of this
study, and should be done in collaboration with the science community.

[Mass and Power Requirements:]{.underline}

The nominal 200 meter drilling system weighs 231 kilograms, and is
scalable to 150, 100, and 50 kg sizes. Simply offloading drilling cable
and hole stability devices lowers the mass to 154 kilograms for a 20
meter depth capability. Removal of 90% of the sample storage mechanism,
resizing the structure to support the lower drilling mass, and the use
of state-of-the-art advanced materials will be required to reach the 100
kilogram mass limit of Cases 1 and 2. (See Figure 2.) The basic design
is scalable to 50 kilograms, but core diameter might require reduction.

As shown in Figure 1, power for all cases is adequate to reach shallow
depths (20 meters). The nominal power requirement of the 200 meter drill
is 163 watts for a seven hour duty cycle per sol (1141 watt-hours).
Twilight operations add 60 watts of power for two hours (120
watt-hours). No night time operations are required, although analysis
remains to be done on the need for nighttime heating. The 275 watt-hour
and 440 watt-hour limits of Cases 1, 2, and 4 would require power
storage for the seven hour duty cycle, but provide ample energy to reach
depths of greater than 20 meters using the BHA designed by Baker Hughes.
All cases have the energy to reach the 20 meter depth, but are
constrained by mass from going much below those levels. Case 3 provides
a total of 1200 watt-hours, which is very nearly the design case for the
baseline 200 meter drill.

It is believed that a 100 kilogram drill design can be optimized to
reach depths of significantly greater than 20 meters, within the mass
and power constraints of Cases 1 and 2.

[FIGURE 2]{.underline}

![](media/image13.pct){width="6.257086614173228in"
height="4.173622047244095in"}

[Test Data:]{.underline}

Test data can be supplied by Baker Hughes on drills using comparable
technologies. Only tested technologies have been employed in the basic
design.

[Technology Development and Costs:]{.underline}

Because the basic design employs only proven technologies, the main
technology work which must be done is to bring the components together
and test them separately and then as assemblies

Cost estimates for technology development and drill DDT&E and production
are available to Government users only, under separate cover.

*Costs of smaller drills would be proportionately less than those of the
200 meter drill.*

The cost risk is very low, because of the confidence in the contractor's
estimates.

[Schedule:]{.underline}

Baker Hughes has stated that they can deliver the 200 meter drill in 24
months from contract go-ahead. There is no reason to believe that the
smaller drills could not be done in that same time period or less. Since
this mission is scheduled for a 2007 launch, the intervening time period
would be employed to good advantage to perform tests on the (state of
the art) individual technologies employed, as well as to perform some
integrated system tests to verify that the technologies work together.
This time period is relegated to risk reduction of an already low risk
mission.

The following schedule is an abstract of the "Team E" report, showing
the nominal development schedule for the drill and spacecraft as
envisioned in November of 1999, for a launch in 2009. The drill design
and build is shown for the period from April 2007 to delivery in April
2009. The schedule for the drill can easily be advanced by 26 months to
meet a 2007 launch date. Overlaid on the schedule are milestones 26
months earlier than those of the November 1999 design. The schedule
shows the drill delivery to be six months prior to launch. To meet the
September 22, 2007 launch date, the drill would be delivered about March
21, 2007. The development contract start date could be as late as March
21, 2005, but the start is assumed to be January 1, 2005 to provide
schedule contingency.

**Mars 2007 Milestones 2002 2004 2006 2008 2010**

![](media/image14.pct)

[Mobility:]{.underline}

Assuming terrain avoidance capability on the lander, mobility is not
required with this design. The BHA, as designed, is steerable, to enable
corrections for misalignments in the platform, or for offset drilling.
The only apparent virtue of mobility would be to provide more science,
by drilling more than one hole with the same apparatus. The same end can
be achieved by *drilling more than one offset hole from the same
original location*. The cost-benefits of providing mobility should be
closely examined, but it appears that, based on inputs from the science
community, mobility is primarily required for very shallow drills.

[Implications which the Drilling System would Have on the
Lander]{.underline}:

The landed platform must be able to support the mass of the drill
(50-231 kg) plus the mass of a single core and tailings, a cylinder of
57mm in diameter by one meter in length (perhaps smaller in Case 4). If
multiple cores are to be stored on board, the lander design would have
to accommodate that added mass.

Leveling capability is not critical, because this steerable drill can
accommodate reasonable off-level conditions.

Acreage of any of the drill designs is commensurate with that available
on a Delta-Medium sized spacecraft (2088 kilograms to LEO).

For any design, the Bottom Hole Assembly (BHA) would be comprised of an
anchor and a weight-on-bit (WOB) module, a power module, and a
coring/drilling head module. For Cases 1-3, this assembly would be
approximately 2.4 meters in length.

The 2.4 meter long down-hole assembly provides approximately one meter
sample reservoir length, split between the core and the loose cuttings.
This length can be cut in half to allow more compact packaging of the
drill mechanism on the lander.

The total drill mechanism design also includes core handling and
storage. Cores and cuttings are contained by a sock/sheath, which is
auto-loaded into the drill bit in both the core and cuttings reservoirs.

The well hole will have intermittent casing for stabilization. Because
the top layers of the subsurface are considered the most unstable
portion of the hole, the top \~3 m would have a solid casing. Enough
material for 50% of the total hole depth is carried in the mass totals
for all versions. Also included is a spare down-hole motor and drill bit
(although, in every design, the expected life of the initial drill bit
is longer than the primary mission length).

The ability of this mission can be greatly enhanced by two technologies,
i.e., precision landing and the use of a steerable aeroshell to place
the drill at an exact area predetermined by the science team to have the
greatest possibility of discovering water. These two technologies would
be of benefit to, if not essential to, all drilling missions, since
mobility for any drilling lander in these study cases would be limited.

After landing, it will be necessary to clear away any surface debris
that would interfere with the drill getting its initial bite (for
example, loose rocks and small boulders that would roll or slide). Large
boulders (\>100 kg) would probably be stable enough that the drill can
pass through them and then into the ground below.

[Mission Operations Requirements]{.underline}:

Mission data requirements will depend on the chosen scientific
instrumentation, the amount of in-situ data analysis performed, other
spacecraft instrumentation, and additional customer requirements.

The drilling operations are autonomous, but if a situation is
encountered which requires human intervention, on-board protocols, many
of which have already been developed, will put the drill into a safe
condition, awaiting intervention from Earth. Data requirements for this
contingency operation are undefined, but expected to be well within the
capabilities of the basic spacecraft.

Further details of the 200 meter baseline design are presented in the
attachment, the Team E Report from November, 1999.

[Conclusions:]{.underline}

The baseline 200 meter drill meets JPL design Case 3, and with some
modest scaling, Cases 1 and 2. The concept can be further scaled to meet
Case 4, although this will be a point design for the lighter weight,
shallower hole drill. It will reach a depth of at least 20 meters in
each of these cases. Under Case 4 conditions, commonality with the
deeper drills would be compromised.

*The NASA/Baker Hughes baseline 200 meter drill design has been designed
and rigorously reviewed in the Team E (JPL, JSC, Baker Hughes) activity
of November, 1999. It has satisfied critical reviewers that it is
capable of a low cost, very low risk Mars drilling operation, and with
an inherent design capacity to reach several kilometers in depth. Baker
Hughes has provided NASA with a windfall of proprietary technologies to
enable this mission.*

Although the science community has not yet attached quantified value to
various drilling depths, it is clear that "deeper is better" and that
there is great value to eventually reaching depths of several
kilometers. The Baker Hughes coring drill provides the means of
achieving drilling depths of from 20 meters to several kilometers with
the same basic design.

All versions of the drill produce intact, encased, cores from all
depths, which can be analyzed downhole, or brought to the surface for
further analysis. The cores, because they are protected, would be
suitable for retrieval and return to Earth on subsequent missions.

Proven technologies (proprietary to Baker Hughes) include the methods
for weight-on-bit, dry core drilling, hole stabilization, down-hole and
surface sample analysis, and drill automation. These technologies have
been provided to NASA at no cost.

If it is assumed that NASA will eventually send a deep (several
kilometer) drill to Mars, the baseline design will provide the necessary
testbed to establish proof of concept prior to the time that the agency
must commit to the greater depth. This would probably save the cost of
an entire mission.

Because all versions use existing, proven technologies, the drill can be
delivered in 24 months, at very low cost.

[Recommendations]{.underline}:

It is the recommendation of the JSC team that the Systems Engineering
group for the Mars 2007 mission seriously consider the enormous benefits
of modestly higher mass allocations. Raising the mass limit to 231 kg,
and the power limit to 163 watts would greatly increase both the science
and engineering values of the mission, enabling intact cores (suitable
for sample return) to be brought from up to 200 meters in depth, with
in-situ instrumentation yielding orders of magnitude more scientific
data. And, as a major benefit, the design for the 3-5 kilometer drill
would be proven prior to NASA's commitment to that depth.

[Further Information]{.underline}:

For further information, please contact one of the following:

Humboldt C. Mandell, Jr., Ph.D.

Exploration Office

NASA JSC

\(281\) 483-3977

<humboldt.c.mandell1@jsc.nasa.gov>

Deb Neubek, JSC Team E Lead

Exploration Office

NASA JSC

\(281\) 483-9416

<deborah.j.neubek1@jsc.nasa.gov>

Jeff L. Smith, NASA JPL Team E Lead

NASA JPL

\(818\) 354-1064

<jeffrey.L.Smith@jpl.nasa.gov>

Robert Oberto, NASA JPL Team E Study Lead and Facilitator

NASA JPL

\(818\) 354-5608

<robert.e.oberto@jpl.nasa.gov>

Pete Fontana, Baker Hughes Team E Lead

Baker Hughes

\(713\) 232-7417

<pfontana@deepwater.com>

**APPENDIX D**

**DRILLING WHITE PAPER**

**FROM**

**HONEYBEE ROBOTICS**

![](media/image15.pct)

**Recommendations for Drilling Systems for the Mars 2007 Lander
Mission**

**(Final Draft)**

March 16, 2001

Written by: Shaheed Rafeek

Contributing Authors: Stephen Gorevan

Tom Myrick

Kinyuen Kong

Paul Bartlett

> ![](media/image16.pct){width="5.527777777777778in"
> height="2.7777777777777776e-2in"}

Table of Contents

![](media/image16.pct){width="5.527777777777778in"
height="2.7777777777777776e-2in"}

1.0 Summary 3

2.0 Technical Feasibility 3

2.1 General System Description 3

2.2 Systems Heritage 8

2.3 Drilling System Capabilities 11

2.3.1 Mass/Power/Drilling Depth 11

2.3.2 Bit Wear 12

2.3.3 Sample Acquisition and Transfer 13

2.3.4 Cross Contamination 14

2.3.5 Ice/hydrocarbon samples 14

2.3.6 Downhole Science 14

3.0 Supporting Test Data 15

4.0 Technology Development 15

5.0 Mobility 16

6.0 Schedule 16

6.0 Cost and Risk 16

**1.0** **Summary**

It is the belief of the Honeybee Robotics planetary surface engineering
team that three types of drilling (and sample transfer systems) can be
advanced in time to fly on a 2007 mission. These systems are a highly
mature 2 meter Sample Acquisition and Transfer Mechanism \[SATM\], a 20
meter drill supported by a PIDDP grant and the SATM development and a
revolutionary Inchworm Deep Drilling System.

The 2-meter SATM is a continuous auger-type drill that has a very well
developed (TRL6) prototype that was demonstrated to depths of 1.2 meters
for the cancelled ST4/Champollion mission. The 2-meter SATM can be
deployed from a lander or a rover (lowered to the ground) and have
access to multiple drill sites. The 2M SATM drill is advocated as a
drill development \"floor\" because there could be significant schedule
risks associated with getting any 20 meter drill ready for an \'07
mission. The 2M SATM drill, at TRL 6 will carry virtually no schedule
risk. Having said that, we do believe that two types of 20 meter drills
can be designed, built and tested for an \'07 mission.

One of the two 20 meter drilling systems adovcated is a Deep Drill
Sample Acquisition and Transfer Mechanism (DDSATM) which utilizes a
conventional auger-type (dry) drill consisting of multiple
inter-connected drill tubes. This drill can be deployed in \'07 from a
rover or a lander. The DDSATM, which is currently at TRL 4-5 is being
recommended because we believe that the supporting technology to advance
the design to TRL6 can be ready for the scheduled 2004 cutoff date. The
second 20 meter system uses a combination of DDSATM hardware to lay a
borehole casing along with a tether IDDS (see below) to drill, remove
cuttings and take cores (consolidated and unconsolidated).

The third system we are recommending is an Inch Work Deep Drilling
System \[IDDS\]. This system is less developed than the previous two
systems recommended by Honeybee Robotics but there is heritage that the
IDDS is built on from two previous engineering efforts and the potential
payoff for the IDDS is immense. The Honeybee Robotics planetary surface
systems engineering team has now determined that a 10 to 20 meter
version of the IDDS can be made ready for an \'07 mission. The IDDS is a
revolutionary drilling system. This system, deployed from a rover or
lander drills through soil or rock while reacting all drilling torques
and forces into the local ground. The system walks or inchworms its way
down as it drills and comes back to the surface to remove drill
cuttings. The promise of the IDDS is that after \'07, it could be
developed into a tetherless kilometer class drilling system that can be
launched from a rover as well as a lander. The huge mass savings of a
tetherless IDDS capable of kilometer class drilling (beyond \'07) makes
it an excellent candidate for a MARS subsurface drill.

All of the recommended systems also serve as sophisticated robotic
material handling devices, capable of precisely distributing acquired
samples to in-situ science instruments or sample return containers.

The details of the IDDS, DDSATM and SATM including its current
technology status and heritage, capabilities, required development and
estimated cost are described below. The rationale for making the
recommendations on these drilling systems as being feasible for a 2007
mission is based on an extensive collection of drilling test data
accumulated at Honeybee Robotics. These system performance data are
mostly from low power, low thrust drilling systems and subsystems that
were fabricated and tested over the past 10 years for various commercial
and NASA programs. It is almost certainly true that more work on
planetary surface drilling systems has been performed at Honeybee
Robotics than at any other company in the world.

The 18 years of expertise in developing robotic end-effectors, joints
and precision material handling systems for its commercial client base
such as Space Systems Loral, Lockheed Martin, 3M, IBM, Merck,
Consolidated Edison and Coca-Cola have helped the Honeybee Robotics
drilling systems to maintain a strong sample handling and sample
transfer profile and thus have also been a strong validation factor in
making these recommendations.

2.0 Technical Feasibility

> 2.1 General System Description
>
> 2.11 DDSATM

The **DDSATM** is a scalable drill and sample handling system that can
be used to explore the subsurface of Mars. It consist of a Robotic Drill
Tower (RDT) surrounded by a carousel type Drill Tube Feeder (DTF) as
shown in Figure 1.

##### *Drill Tube Feeder*

![](media/image17.jpeg){width="1.4590277777777778in" height="2.51875in"}
The DTF is a method of precisely positioning and presenting drill tubes
to an interfacing drill head, as well as presenting empty slots for the
subsequent removal of drill tubes during the extraction phase. Each
drill tube is a simple auger, which is drilled into to the surface by
the RDT. The DTF contains storage slots for each drill string. These
storage slots are on a rotary platform for precise positioning and to
allow the RDT access to any drill tube so that a choice of starter drill
tube is available. The starter drill tube can be a coring bit, or an
in-situ science bit (see Figure 1). In this version of the 20 meter
drill, chip removal to the surface will be accomplished with the auger
flights.

> Figure 1- Robotic Drill Tower with Drill Tube Feeder (l), Starter Bit
> with Coring Mechanism (c) and Deployed Drill Tubes (r).
>
> ***Drill Tube Attach/Detach Mechanisms***
>
> ![](media/image20.jpeg){width="1.7159722222222222in"
> height="3.3583333333333334in"}Because the devices described for the
> 2007 mission must operate remotely and autonomously, special designs
> must be developed to insure that the drill tubes can be properly
> secured to one another in a very robust and reliable way by robotic
> devices. Special effort therefore must be devoted to developing the
> Drill Tube Attach/Detach Mechanisms (DTADM), a concept of which is
> shown in Figure 2**.**
>
> For the DDSATM version of the 20 meter drill, the connected tubes will
> be capable of transmitting power and signal across the joints in a
> multiplexing mode to operate the science/sample acquisition systems in
> the lead drill tube. Slip rings on the RDT drill head will bring power
> and signal out from the tubes to a control system. In the second 20
> meter drill concept, there will be no requirement for power and signal
> transfer across the joints.

######### Figure 2 -- Drill Tube Connection 

##### *Borehole Casing (Option)*

> It is highly possible that the top layer of the Martian surface will
> consist of dry, loose material that is susceptible to borehole
> collapse. If the DDSATM is required to make several trips to the
> surface for sample drop-off, there will be the possibility of having
> to re-drill the entry layer of the borehole each time. Additionally, a
> collapse of the upper section of the borehole, while the drill is
> operating, will induce parasitic drag torque that can lead to increase
> in energy consumption. To reduce these effects, an upper layer
> borehole casing can be deployed for the first meter down the borehole
> with the lead drill tube (as an option).
>
> The second 20 meter drill system will eliminate the problem of
> borehole collapse since the casings will be continuous to solid
> bedrock.

###### 2.12 The 2-meter SATM

###### The 2-meter SATM is a direct scaled up technology from a 1-meter SATM that was prototyped and tested for the ST4/Champollion mission. It has a very mature technology base to a TRL6 level and will require very little development to be ready for a 2007 mission. This system is recommended as an alternative if there are concerns for meeting the technology readiness level for a 20+ meter system.

#### Key Features of the 2-meter SATM:

-   Core through solid phase material with high compressive strength
    (200 MPa).

-   Acquire stratigraphy maintained samples/cores to depths of 2 meter.

-   Selectively acquire samples/cores of different length and at
    different depths below the surface without cross contamination.

-   Positive sample ejection mechanism for micro gravity environment.

-   Act as a sample handling tool to open and manipulate in-situ
    instruments and sample return containers during sample hand-off.

-   Utilize passive brush station for internal (and external) chamber
    cleaning.

-   Integrated core break-off and capture mechanism in cutting tip.

![](media/image21.jpeg){width="2.2131944444444445in"
height="3.1131944444444444in"}The 2-meter SATM is a fully autonomous
electromechanical device capable of performing multiple functions in
support of Planetary exploration missions (see Figure 3). The 2-meter
SATM consists of a single drill string that is driven into the surface
by a lead screw based thrust drive train. At the tip of the drill string
is an auger with a custom designed cutting tip. The auger tip rotates at
low (100-300) RPMs via a motor/gearbox combination located at the top of
the drill string.

In the material handling mode, a close loop feedback system on the auger
rotary position provides precise location of key features on the auger
tip so that interface operations (such as engaging a drive mechanism to
open/close a drop-off chamber door) can be accomplished. Within the
auger body, there is a pushrod that acts as a center-cutting tip during
the drilling mode. In the coring mode, the push rod is retracted into
the auger body, exposing the sample cavity.

![](media/image22.png) **Figure 3 -- 2 meter SATM**

In addition to the vertical drill string axis, the SATM can also be
equipped with an Index axis, that would allow it to interface with
in-situ instruments along the circumference of the arc scribed by the
drill tip (see Figure 4). A close loop feedback system together with a
precision gear head allows the Index axis to precisely align the drill
tip with mechanical interfaces on the instruments.

##### 

##### Figure 4 -- 2-meter SATM Index Circle

###### *2.12 The Inchworm Deep Drilling System \[IDDS\]*

![](media/image23.png)The Inchworm Deep Drilling System \[IDDS\] is a
compact, subsurface drilling system capable of accessing regions deep
below the surface of Mars. Several versions of the IDDS are being
recommended. A smaller tether unit that's capable of penetrating 20
meters below the surface and a larger tetherless unit for 1 Km access.
The advantage of this dual unit approach is that the technology
developed under the tether unit will feed directly into the tetherless
unit. These concepts are being developed at Honeybee Robotics to enable
future subsurface science missions at depths of 20 meters to one
kilometer. The 20-meter tether IDDS provides a compact system that can
be mounted on a rover platform to sample multiple sites and can be ready
for the 2007 mission (see Figure 5).

The long-range development of the tetherless IDDS is important when
subsurface access to one kilometer and beyond is required. At these
great distances, there are significant tether management issues that
need to be overcome. The tetherless IDDS gets around these problems
through the employment of low thrust drilling techniques that require no
more power than that offered by a Sterling Power System (SPS). The
tether free, self-powered and self-propelling device will be capable of
burrowing to a specified depth and retrieving samples or of transporting
instruments along with it for in-situ analysis. The tetherless version
will be a long range development beyond 2007.

**Fig 5: Rover Deployed IDDS**

![](media/image24.jpeg){width="1.3152777777777778in"
height="3.7368055555555557in"}

##### The proposed development of the IDDS can be seen as taking an incremental approach by first building a tether unit that goes 10-20 meter below the subsurface. This tether unit will be used to study the performance of the walking, drilling and sampling sub-systems of the IDDS. Nevertheless, as a long-term goal, a successful tether IDDS demonstration will lead to the development of the tetherless unit where the system will be re-engineered with an on-board SPS. NASA is currently supporting the SPS development. The IDDS development will also explore the option of deploying casings down the borehole for subsurface regions where hole collapse can occur. 

##### 

##### The IDDS is capable of taking a core in its forward section and walks by collapsing and extending the forward an aft reaction legs while telescoping the body in and out in an "inchworm" style (see Figure 6)

> **Figure 6: Tether IDDS**

##### ![](media/image25.jpeg){width="1.9930555555555556in" height="5.7in"}*2.2 Systems Heritage*

The core technology for the recommended drill systems has been developed
over the past 10 years through numerous NASA and commercial programs.
Specifically, over the past 5-6 years, these technologies were advanced
to a very high fidelity under two separate NASA contracts.

The first of these two contracts was geared towards the development of a
TRL6 drilling system for the ST4/Champollion mission to a comet. The
hardware that was developed produced a 1.20 meter SATM that was
successfully demonstrated in a laboratory environment (see Figure 7).
The prototype unit was further equipped with an infinitely adjustable
sample cavity volume making it ideal for meeting the requirements of
various in-situ instruments on ST4/Champollion mission. Once the samples
were acquired, SATM was able to perform the functions of a very
sophisticated material handling system by precisely manipulating and
positioning the acquired samples to in-situ instruments such as
microscopes, IR fiber analyzers and gas chromatograph mass
spectrometers-GCMS (see Figure 8 &9).

![](media/image26.png)

> **Figure 7 -- ST4/Champollion SATM**
>
> Finally, with an adjustable sample cavity, SATM was also required to
> collect, drop-off, and seal samples (large volume) for a sample return
> mission. The SATM drill tip itself was used as a tool (nut driver) to
> hermetically seal the collected samples in a multi-chamber sample
> return container.
>
> **Figure 8 -- SATM interfacing with GCMS**
>
> ![](media/image27.jpeg){width="1.2277777777777779in"
> height="1.8625in"} **Figure 9 -- SATM Acquiring a 1-meter sample in
> Limestone**

![](media/image31.jpeg){width="1.85in" height="1.3875in"} **Figure 10 --
SATM Transferring a Stratigraphy Maintained Sample to a Chamber**

![](media/image34.jpeg){width="4.2in" height="3.248611111111111in"}The
second NASA contract that resulted in advanced drill technology
development was awarded to Honeybee Robotics to develop the Mars '03
Athena Mini-Corer (see Figure 11). The Mini-Corer which was developed to
TRL5 can obtain 8mm diameter, 25 mm long rock cores from strong rocks.

**Figure 11 -- Athena Mini-Corer**

It is important to report that the key features of the Mini-Corer are
highly scalable and can be reworked into coring systems with very
different capabilities than that of the Athena Mini-Corer. The Athena
Mini-corer is a proven technology that utilizes low force and energy to
accomplish controlled core acquisition and manipulation. The device was
designed to drill to a desired depth, break-off and retain the core from
the base rock and present the core to instruments and finally positively
eject the core into a sample container. This drill can acquire cores
from both soft and hard rocks using as little as 4-6 watt-hours of
energy. Specially designed drill teeth and an entry brad provide for a
stable entry into the rock and minimal reaction force. The construction
of the Mini-Corer has focused on low mass, high stiffness, extreme
robustness and application flexibility.

Robotic Joints have been developed by Honeybee Robotics to assist in the
Space Station construction. The technology for these highly preloaded
joints will have great transfer potential for use on the DDSATM multi
segmented drill string. Other types of attachment mechanisms developed
by Honeybee for attaching robots to worksite attachment nodes will also
have high transfer technology potential (see Figure 12)

> ![](media/image35.png) **Figure 12 -- Robotic Interfaced Quick
> Disconnect Struss Joints**

With the SATM and Mini-Corer scalable technologies as baseline, and with
several more years of additional development (which has already begun,
through a PIDDP and an SBIR contacts) Honeybee Robotics is recommending
the IDDS, 20+ meter DDSATM and the 2-meter SATM to the study group as
highly feasible designs that can perform the tasks of drilling below the
surface while taking stratigraphy maintained cores (or unconsolidated
samples) at any selected depth within that range.

> **2.3 Drill System Capabilities**
>
> The following sections outline the capabilities and justifications for
> the recommended drilling system.
>
> **2.3.1 Mass/Power/Drilling Depth**
>
> The achievable drill depths for the three resource cases when drilling
> in basalt are shown in table 1.
>
> Drill thrust -- 1500N (for a 40mm diameter shaft)
>
> Mass (RDT and DTF) - 45kg
>
> Drill tube mass -- 55 Kg (cases 1,2)

  ------------- ----------------------- -------- ---------- -------------- ---------- ----------- ----------- ---------- --
                                                            **Drill                                                      
                                                            Parameters**                                                 

                                                                                                                         

  **DDSATM**                            **Case              **Case 2**                **Case 3**                         
                                        1**                                                                              

                                                                                                  **Units**              

  Power on                              257                 257                       257         Watts                  
  demand                                                                                                                 

  Drill time                            0.77                0.86                      2.33        hr                     
  (day)                                                                                                                  

  Drill time                            0.29                0.86                      2.33        hr                     
  (night)                                                                                                                

  Total drill                           1.06                1.72                      4.66        hr                     
  time                                                                                                                   

  Penetration                           0.1                 0.1                       0.1         m/hr                   
  Rate (basalt)                                                                                                          

  Drill                                 0.106               0.172                     0.466       m/day                  
  Depth/day                                                                                                              

  Mission Time                          108                 1080                      1080        days                   

  Total drill                           11.448              185.76                    503.28      m                      
  Depth                                                                                                                  

  Actual Drill                          11.5                20+\*                     20+\*       m                      
  Depth                                                                                                                  

                                                                                                                         

  \* Design                                                                                                              
  limited                                                                                                                

                                                                                                                         
  ------------- ----------------------- -------- ---------- -------------- ---------- ----------- ----------- ---------- --

> **TABLE 1- DDSATM Drill Performance Summary**

With a power source delivering 275W-hr per Martian Sol, the DDSATM will
be able to achieve a penetration rate of 0.1 meter per hour based on
extrapolated test data from basalt drill tests conducted at Honeybee
Robotics. For a mission lifetime of 0.3 years, the total depth
attainable will be 11.5 meters with the assumption that there is
continuous drilling and no extractions to the surface for sample
drop-off.

Based on the available mass of 100Kg (cases 1 and 2), the DDSATM can
accommodate a maximum of 45 one-meter drill tubes after accounting for
the mass for the drill mechanisms and support structure. Each drill tube
mass is estimated to be 1.2Kg for a total mass of 54Kgs. For the
recommended system, only 20-21 drill strings will needed to get to 20
meters. The additional drill tubes can be considered as replacement
starter bits or science payload lead drill bit. The supporting structure
for DTF and RDT takes up the additional 46Kg. Any additional mass (case
3) will be considered as margins or can be used for replacement drill
bits. It might be possible that after testing these systems in a
relevant environment, the envelope for the drill depths might be able to
be pushed out beyond the 20 meter range but until those tests are done,
it is very difficult to make an accurate assessment on the upper limit
beyond 20 meters.

It should be pointed out that for cases 2 and 3, the limiting factor for
drill depth is the structural stiffness of the drill string and the
associated logistics of connecting the drill tubes together. The wear of
the bits will also be a factor.

The 2-meter SATM has already been demonstrated in a 1-meter limestone
setting and will have an easier task of meeting the requirements of the
2007 mission. The mass for the 2-meter SATM is estimated to be 30Kg.
With a similar drill shaft diameter as the DDSATM, it will posses
similar drilling characteristics for penetration rates, thrusts and
power as shown in table 1.

**IDDS**

Cable density -- 1Kg/meter

IDDS mass -- 35 Kg (body, launch tube and reel)

  -------------------------- ----------- -------------- ----------- -----------
                                         **Drill                    
                                         Parameters**               

                                                                    

  **IDDS**                   **Case 1**  **Case 2**     **Case 3**  

                                                                    **Units**

  Power on demand            600         600            600         Watts

  Drill time (day)           0.33        0.36           1           hr

  Drill time (night)         0.13        0.36           1           hr

  Total drill time           0.46        0.72           2           hr

  Penetration Rate (basalt)  0.1         0.1            0.1         m/hr

  Drill Depth/day            0.046       0.072          0.2         m/day

  Mission Time               108         1080           1080        days

  Total drill Depth          4.968       77.76          216         m

  Actual Drill Depth         5           65\*           110\*       m

                                                                    

  \* Mass limited                                                   
  -------------------------- ----------- -------------- ----------- -----------

> **2.3.2 Bit Wear**
>
> Because of the objective of drilling to a depth of 10-20 meters, there
> will need to be drill bits that are capable of withstanding the wear
> of going through hard rocks as well as loose abrasive type regoliths.
> Honeybee Robotics has developed proprietary bit geometry and has
> identified slow wear material that would produce long lasting bits.
> However, longevity tests will need to be conducted in basalt and other
> hard rock to ensure that these materials can last to those depths.
> Coring tests done for Athena Mini-Corer have shown promising results
> so far. Additionally, the DDSATM will have a split bit arrangement
> comprising of an inner and outer section, which optimizes the thrust
> loads to produce the most efficient cutting rate for a given rock
> type. Having multiple start bit is yet another option for the DDSATM
> to counter problems with drill bit wear, especially if there are more
> hard rocks encountered in the borehole. In this case, when the system
> sense's a dramatic slow down in penetration rate, it will retract the
> start bit back to the surface, place it on the DTF, and take a new
> start bit.
>
> **2.3.3 Sample Acquisition and Transfer**
>
> To support in-situ science and sample return missions, a sample
> acquisition chamber located at the drill tip, opens (after reaching
> the desired depth) to begin sample acquisition. To open the chamber, a
> center-drill/pushrod tip is retracted as the drill advances down the
> borehole. Continued drilling for a known depth will ensure that the
> desired amount of sample in the form of a stratigraphy maintained core
> is obtained (the depth is continuously monitored by a close loop
> feedback on the vertical drill string axis). It is important to point
> out that this form of core acquisition is unique (may be the only one
> in the world) and is capable of taking both consolidated and
> unconsolidated cores. The motor(s) inside this lead drill string
> provide a method of moving the center-drill/pushrod device used for
> drilling/sample ejection and also for rotating a shear tube which
> shears the sampled core and captures it inside the sample chamber (see
> Figure 13).
>
> ![](media/image37.jpeg){width="2.3in" height="2.165277777777778in"}To
> drop-off a sample, the DDSATM will extract all the drill tubes from
> the borehole and place them back on the DTF. The time it takes to
> extract a drill tube out of the borehole and place it back on to the
> DTF is estimated to be 15minutes each. When the RDT has the lead drill
> tube in its head, an instrument carousel will rotate under the drill
> guide and present an interface for the drill tip.
>
> The RDT will lower the drill tube along the Z-axis until the drill tip
> engages the carousel opening. The motors in the drill tip will then be
> activated **Figure 13- C re Acquisition Sequence**
>
> to open the chamber and push the sample out using the pushrod. The
> carousel will then index over to the required instrument and deliver
> the sample. Alternatively, the entire RDT can be mounted on an index
> axis, which would allow the drill tip to access any sample chamber
> along a circular path as shown earlier in the 2-meter SATM system (see
> Figure 4).
>
> An alternate form of sample acquisition that was used in the
> ST4/Champollion SATM system, collected loose drill cuttings and stored
> it in an adjustable sample cavity. A pushrod in the chamber positively
> ejects the sample to instruments. Similar sample acquisition system
> will be employed in the IDDS.
>
> In both of the sample collection methods, an estimated **4 cubic
> centimeters** (cc) of samples can be collected (larger sizes can be
> taken in consolidated bedrock). The adjustable nature of the sample
> chamber allows you to take different volumes of samples, which is a
> good feature to have if multiple science instruments are onboard,
> since each may have a different sample volume requirement. These form
> of sample acquisition and transfer were successfully demonstrated in
> the Athena Mini-Corer and also in the ST4/Champollion systems.
>
> Position sensors on the Z-axis of the RDT in combination with counters
> for each drill tube on the DTF can be utilized to determine the exact
> position of the drill tip. The top of the Martian landscape can be
> determined through the use of a thrust sensor (which shows a spike in
> its reading upon contact with the surface, as the RDT Z-axis is
> lowered) on the RDT which will zero the drill depth and allow for a
> more accurate depth reading.
>
> **2.3.4 Cross Contamination**
>
> Once the sample is acquired, the chamber door is closed over the core
> to prevent mixing with material from other depths. To further reduce
> cross contamination within the sample chamber, a passive brush station
> can be made available to the lead drill tube (or the IDDS) every time
> a sample is dropped off. The RDT will present the lead drill tube with
> the chamber open, to the brush station. By rotating the drill over the
> brush, any loose samples within the chamber will be removed. Forward
> contamination (Earth based) can be reduced through heat sterilization
> of component parts in the acquisition chamber prior to launch and also
> by avoiding the use of any type of cutting fluid. Protection during
> launch and cruise can be accomplished by sealing the drill tip with a
> plug or foil type membrane which can be ejected by the drill pushrod
> prior to drilling operations on the surface of Mars.
>
> **2.3.5 Ice/hydrocarbon samples**
>
> The DDSATM, 2-meter SATM and IDDS will acquire and maintain an ice
> sample but may not be able to deliver it to surface instrument without
> some phase change if drill depths are too large. Because of the
> relatively low RPM at the cutting tip, the temperature rise is not
> very substantial to cause melting (usually in the range of 5 degrees
> above the surroundings). For solid hydrocarbons, the temperature
> effect will be negligible.
>
> **2.3.6 Downhole Science**
>
> The lead drill tube can accommodate a science payload in its cavity,
> which is supplied with power and signal lines that run down the inside
> of the drill string. The volume available is defined by a cross
> section of approximately 30mm diameter by a length of 500mm. The
> actual payload as an example can be a DS2 type laser diode, a Time of
> Flight spectrometer (developed by Applied Physics Lab.) or even a
> camera and light source, looking out through a sapphire window brazed
> onto the drill tubing. For a non percussive drill system, the
> instruments contained in the lead drill string will not see any thrust
> loads and will only need to survive slow speed rotations. With the
> availability of power down the drill string, the electronics to drive
> the instruments can be kept warm with heaters.
>
> Other types of science payload can be accommodated so long as it can
> be packaged to fit the available volume. For example the IDDS can be
> coupled to several types of science payload and lowered down the
> borehole.

**3.0 Supporting Test Data**

Supporting test data will be supplied at the workshop.

**4.0 Technology Development**

As stated earlier the technology developed as part of Mars '03 Athena
Payload includes a drilling device (Mini-corer) capable of taking
stratigraphy maintained core samples from hard (Basalt) surface rocks
with minimum energy requirement (**4-6 W-hr for a 8mm diameter x 25 mm
long core in Basalt**). In order to extend this technology for coring
deep below the surface, new miniaturization technology needs to be
developed to package these core break-off mechanisms at the tip of the
lead drill tube. The larger drill tube diameter (40mm) will make this
task a little simpler. Preliminary motors and mechanism layout shows
that this miniaturization effort is feasible with currently available
motor technology. Alternate core break-off technology will also be
looked at and traded.

The technology to automate the drill tube connections is another area
that will be given more attention. These connections have to be robust,
possess high stiffness, allows power and signal to pass through and
feature high accuracy and repeatability to allow the RDT to do the
changeouts.

For the IDDS, it will be necessary to develop strong wall reaction
mechanisms when going from soft to hard samples. This can be
accomplished through the use of borehole casings that can be deployed by
the IDDS.

This technology development will build on and extend the previous
accomplishments achieved under the Mars Sample Return mission -- Athena
Payload and the New Millenium Program ST4/Champollion effort.
Technologies from both of these programs -- the Mini-Corer (Mars '03)
and the SATM (ST4) are the basis for the more advanced DDSATM. The
knowledge gained by advancing and improving the drilling and sampling
techniques started on those projects can be significant and far
reaching.

**5.0 Mobility**

The IDDS and the 2-meter SATM is ideal for a mobile platform. With a
mass of approximately 30 Kg, the 2-meter SATM in our estimation will
provide valuable science return for mass, power and time constraints
available to the mission. The risk involved with a mobile platform is
minimal and is largely due to the stability of the rover base and its
effect on the repeatability of the SATM, in terms of finding the
borehole (after a sample drop-off). This can be overcome with deployed
stabilizers when a suitable drill site is selected at a modest overall
cost and mass increase to the mission. The advantage of the mobile
platform is the higher probability that will now be available to find
interesting samples and sites to study. A failure to find any
interesting science in one location for a fixed platform system will not
bring the best returns for the dollar and effort put into a mission of
that nature.

The 20-meter IDDS will posses a mass of approximately 50 Kg making it an
even more attractive candidate for a rover platform.

The larger DDSATM with a DTF system on board, carrying multiple borehole
casings and starter bits, will provide a greater challenge for a mobile
platform.

####### 6.0 Schedule 

The two systems recommended are appropriately designed to have the
technology readiness level as called out in the statement of work. The
2-meter SATM is the most advanced of the two systems but lack the
drilling depth of the DDSATM. The DDSATM, with an accelerated
development schedule for those items that needs further development,
will be capable of meeting the 2007 mission technology milestones.

**7.0 Cost and Risk**

To be discussed at the workshop.

**APPENDIX E**

**DRILLING WHAT PAPER**

**FROM**

**ASI**

Mars 2007 Drilling Feasibility Team

Italian contribution to white paper

Prepared by:

A. Coradini, R. Bianchi, M.C. De Sanctis Istituto di Astrofisica
Spaziale -- CNR Roma

P.G. Magnani, M. Malychev, E. Re Tecnospazio S.p.A. - Milano

S. Espinasse, E. Flamini, R. Mugnuolo, A. Olivieri Agenzia Spaziale
Italiana

A. Ercoli Finzi Politecnico di Milano

Dated of Issue: March 15^th^ , 2001

# INTRODUCTION

This paper has been prepared to provide technological proposals to the
challenge of drilling on Mars for the \'07 Lander and beyond. The paper
constitutes the Italian contribution to the 2007 Mars Drilling
Feasibility Workshop that will take place at the Lunar and Planetary
Institute (LPI) in Houston, Texas, February 27-28, 2001.

Drilling on Mars is clearly a mission that could provide a wealth of
information, in particular in the of geology of the planet, and help to
clarify the questions raised regarding such aspects as stratification,
erosion and morphology of the terrain that have been raised by previous
missions including the current Global Surveyor mission. Drilling could
also potentially resolve the debate regarding the presence of water in
its various phases and organic material.

The proposed solutions contained herein have been identified bearing in
mind the constraints indicated in the request regarding mass, energy and
time, as well as the schedule for the 2007 mission. These constraints
require the selected solution be not only compact and power efficient
but also the technology utilised should not need a lengthy research and
development period.

# [SCIENCE AND INSTRUMENTS]{.underline}

## [Science]{.underline}

The study of surface and subsurface mineralogy of Martian soil and rocks
is the key for understanding the chemico-physical processes that lead
formation and evolution of the red planet. The water and other volatiles
history, as well as weathering processes are the signatures of present
and past environmental conditions, associated to the possibility for
life. Surface samples are highly influenced by exogenic processes
(weathering, erosion, sedimentation, impact) that alter their original
properties. So, the analyses of uncontaminated samples by means of
instrumented drillers and in situ analytic stations are the key for
unambiguous interpretation of the original environment that lead rock
formation. Analysis of subsurface layers is the only approach that
warranty measurements on samples close to their original composition.
Scientific goals are strictly related to the depth of the borehole;
straight water detection ask for deep penetrations function of latitude
and local geology, bedrock analysis requires samples from depths,
probably ranging in 20-150m, in function of site geology, and analysis
of soil need few meters in depth.

> The Mars exploration asks for a detailed in-situ investigation of the
> Martian surface and subsurface. At present, only the Viking 1-2
> missions and the Pathfinder one succeeded in obtaining information on
> the composition of the Martian surface. In fact sample analysis is
> needed in order to improve our knowledge on the following topics:

-   Identify the presence biological history of Mars and search for
    possible indicators of life.

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-   Constrain the amount of water on the planet and put it in relation
    with the present and past geologic and climatic history of Mars, at
    least at local scale.

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-   Determine the nature of local geology, chemistry and mineralogy.

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-   Study the Mars environment in terms of human survival on the
    surface.

> The previous scientific goals were considered of high priority in
> establishing the plan for Mars Exploration and are hardly achieved
> when studying only the uppermost layers of the Martian surface. In
> fact the upper few meters of the surface materials underwent to a deep
> reworking and elaboration due to erosion, transportation, and
> deposition phenomena that are still acting on the Mars surface, and
> that can be much more efficient in the past.
>
> The study of the upper layers of the Martian surface will be the first
> step in understanding the complex geo-climatological evolution of
> Mars: in fact it has been suggested that over the course of geologic
> history, a volume of impact ejecta has been produced that is
> equivalent to a global layer up to 2 km thick, overlying the original
> bedrock. This material is termed the megaregolith. In ancient
> terrains, it may occur near the surface, likely interbedded with
> volcanics and sediments. In younger terrains, it may be buried under
> significant amounts of later, undisrupted deposits. Recent images from
> the Mars Global Surveyor camera, for example, show fine-scale
> continuous layering up to 5 km in thickness in deposits exposed in the
> walls of Valles Marineris .

Superficial deposits are made of fine-grained mobile (aeolian) and
indurated (duricrust) materials. Composition is approximately basaltic,
although concentrations of iron oxides (5-10% magnetic) and salts are
possible. Rocks may be embedded in the material.

From radio and radar observations, providing information on the upper
0.1 to 10 m of the Martian crust, we know that subsurface properties
seem to be slightly different from those at the surface, suggesting
subsurface layering in many places. In the first meters of the soil, the
following characteristics are expected: bulk soil porosity of 50%,
thermal conductivity of 2 W m^-1^ K^-1^ (±1) , a density between 1. and
1.6 g cm^-3^ for the dry particulate material dominating the surface.

The exact nature and amount of H~2~O in Martian surface materials is
under debate, but is generally accepted that water in some form
(absorbed, ice, in hydration) is ubiquitous in amounts that varies in
the range of less than one percent to few percent. Geological evidence
indicates that there are, or were, great quantities of water close to
the Martian surface. The stability of ice in ground is controlled by the
atmospheric pressure and the ground temperature. Several models have
been developed to asses the stability of water ice under the present
Martian conditions.

Ground ice, on the surface, is thermodynamically unstable at latitudes
of \~40°: the sublimation rate depends on the surface temperature and
local thermal and diffusive properties of the crust. Local depths of
desiccation at low-latitudes, that are function of these properties,
their variation with depth, and the potential for replenishment from
deeper reservoir of subpermafrost groundwater, range from one cm to one
kilometer. Segregated water deposits, in the northern plains, can be be
present: the volatile stratigraphy of the these regions can be quite
complex, dominated by multiple, overlapping deposits of water ice.

> Hydrates are formed when hydrocarbons, and other gases (like CO~2~ and
> H~2~S), are concentrated under condition of high pressure and low
> temperature in the presence of H~2~O. As the internal heat flow of
> Mars has declined with time, the resulting downward propagation of the
> freezing-front at the base of the cryosphere would have incorporated
> any subsurface methane that exists as hydrate. These hydrates could
> occur in concentrations ranging from a dispersed contaminant, to
> massive deposit. Several authors argued that substantial amounts of
> CO~2~ hydrate might also be present in the Martian subsurface. The
> stability field of CO~2~ hydrate is also similar, but shifted to
> slightly shallower depths -- extending from \~5 m (corresponding to a
> confining pressure of \~50 kPa) at 200 K to a maximum depth defined by
> the location of the 283 K isotherm. Liquid CO~2~ is possibly present
> in the subsurface as inclusions and localized pockets. The ice that is
> likely to be present near the surface at middle to high latitudes and
> below the desiccation zone at low latitudes may be pure water ice, ice
> intermixed with mineral or salt grains, or a CO~2~-H~2~O clathrate.
>
> The search for subsurface water has become a primary focus of Mars
> exploration. Its abundance and distribution (both as ground ice and
> groundwater) have important implications for understanding the
> geologic, hydrologic, and climatic evolution of the planet; the
> potential origin and continued survival of life; and the accessibility
> of a critical *in situ* resource for sustaining future human
> explorers. Water detection can be direct for great depths, but
> inferred by accurate analysis of uncontaminated bedrock or soil rock
> specimens collectable at relative shallow depths: hydrated minerals
> like montmorillonite and nontronite as well as (OH)^-^ and
> H~2~O-bearing silicates are expected on Mars. Furthermore, pyroxene
> minerals, lithium, beryllium and boron have prove useful in
> terrestrial studies of magmatic water and their petrologic analysis
> allow the comprehension of the outgassing history of Mars. Geomorphic
> analysis of sedimentary particles are also important to characterize
> the role of water during sedimentary processes. Then, subsurface
> materials on Mars play a crucial role in understanding the geological
> history of the planet and a drilling program is mandatory for a right
> approach of Mars discovery.
>
> Compositional information on soil components has been derived from
> ground-based, airborne and spacecraft observations using spectroscopic
> remote sensing from the Visible to the Infrared. Mafic ferrous
> minerals, carbonates, sulfates, hydrates, clays and ferric materials
> have been identified as components of Mars. Important results have
> been obtained also using the IR spectrometer ISM, flown on the Phobos
> 2 mission. New information about Martian soils and rocks have been
> collected from Pathfinder mission. The Martian surface can be grouped
> in three major spectral units: **bright red units** (probably fine
> grained windblown dust), **intermediate bright red material**
> (probably indurated aeolian debris or duricrust), and **dark units**
> (perhaps coarse rocky debris, hematitic or oxidized basalts). The very
> red materials are located in the ancient highlands and young volcanoes
> and are very rich in Fe^3+^. Relating the Viking color maps with
> telescopic spectra, it has been found that the bright red materials
> are consistent with palagonites or iron-rich silica gels, the less
> red, dark materials are similar to basalts with a thin oxidized
> coating, and the very dark red areas are similar to non-hydroxylated
> hematitic materials. The Martian red color is normally attributed to
> ferric iron that shows a characteristic feature in the Martian spectra
> and could be used as a "marker" of the degree of oxidation. Its
> dependence on depth will give an insight into the depth of the
> oxidation processes. Iron oxides, oxidized basalts, palagonites,
> olivine and pyroxenes, clays, carbonates, and sulfates are all
> elements detectable by in situ instrumentation and keys for the planet
> evolution history.
>
> In view of the previous discussion, it is clear that the study of the
> Martian subsurface will provide important constraints on Martian
> petrology as well as on nature, timing and duration of alteration and
> sedimentation processes. Up to present, the Viking and Pathfinder
> investigations have studied only the upper layers of the soil. The
> Martian soil analyzed by the two Viking landers showed a surprising
> similarity, despite the great distance between the two landing sites:
> it will be extremely important to verify if this similarity is also
> present in different areas and, particularly, in the subsurface
> layers. The study of the Mars subsurface can give us an indication of
> how deeply the weathering has modified the Martian surface. A driller
> able to penetrate and collect different kinds of materials, both loose
> and hard, is crucial to investigate this complex subsurface structure.
>
> A drilling system, coupled with an in situ analysis package, is needed
> to perform in situ investigations as required by the MEPAG planning
> document. According to the document, the main objectives are:

**Search for possible liquid water in the subsurface.** This requires
drilling and instruments to detect water in all forms, CO~2~ clathrate,
and to analyze rocks, soils and ices for organic compounds or to detect
life. Drill initially to 2 m depth and later to 100s of meters to detect
thin films (\~50 μm) of water and major and trace volatiles in ices in
surface and subsurface soils, the biogenic elements (e.g., C, H, N, O, P
and S), organic compounds (e.g., amino acids, proteins, carbohydrates,
lipids, nucleic acids, etc.) and chirality.

**Explore high priority candidate sites for evidence of extant (active
or dormant) life.** Basic measurements are likely to include both in
situ analysis, and laboratory analysis of pristine samples to search for
organic and inorganic biosignatures, metabolic activity, isotopic
fractionation, disequilibrium chemistry, etc. Requires in situ life
experiments on subsurface materials and laboratory analysis of returned
samples.

**Determine the nature and inventory of organic carbon in representative
soils and ices of the Martian crust.** Requires in situ analysis of
surface and subsurface soils and ices (to a few m depth) to search for
gradients in organic compounds and to detect seasonal fluxes in carbon
dioxide and reduced gases (e.g. methane, ammonia, etc.). Returned
samples to analyze cores of soil and rock for organic compounds,
including molecular structures, and stable isotope compositions (e.g. H,
C, N, S).

**Determine the distribution of oxidants and their correlation with
organics**. The distribution of oxidants in the Martian crust is likely
to have been a controlling factor in determining where, when and how
life might have developed. Requires in situ experiments to determine
elemental chemistry and mineralogy at one targeted low latitude site and
1.0 meter depth to determine the spatial and depth distribution of
specific classes of oxidizing compounds (e.g., peroxides, etc.).

**Analysis of sedimentary deposits**. Such deposits provide the best
repositories for preserving a fossil record of ancient Martian life.
Requires in situ measurements (e.g. laser Raman, infrared spectroscopy,
X-ray diffraction, /X-ray fluorescence, etc.) to determine the
mineralogy and geochemistry of potential aqueous minerals (e.g.
carbonates, phosphates, silica, sulfates, halides, borates, metallic
oxides and sulfides, clays, etc.), including hydrous weathering products
formed by interactions of primary lithologies with water.

**Search for Martian fossils**. These require in situ analyses of
aqueous sedimentary lithologies (e.g. using infrared-spectroscopy, X-ray
iffraction/fluorescence, etc.) to determine the mineralogies,
microtextures and organic contents of aqueous lithologies. Return of for
detailed microscopic, geochemical, mineralogical characterization.

**Determine the timing and duration of hydrologic activity**. In situ
search (using mobile platforms and subsurface drills) to explore for
aqueous, water-formed geomorphic features, and diagnostic meso-scale
sedimentary structures indicative of hydrologic activity. Integrated
petrographic and geochemical analyses for understanding initial isotopic
ratios and the effects of shock metamorphism and weathering processes on
the reliability of age dates. Sampling strategies could include sites
where diverse lithologies could be sampled at one place.

Subsurface samples are much less affected by any kind of weathering and,
at the same time, the possibility to collect bedrocks is increased. The
need of collecting uncontaminated samples can be greatly simplified by
collecting subsurface samples with a drill device In fact a drill
permitting the collection of both rock and regolith materials leaves the
possibility to choose the landing site based on other relevant criteria
(safe landing, scientific interest, etc). On bedrocks it is possible to
obtain samples on which absolute radiometric datation can be performed.
A drill device will increase on one side the complexity of the
collecting system but it will also simplify it by reducing considerably
the area to which the sampling device needs to access without requiring
any mobility capability.

**How important is the penetration depth**

***Shallow penetration***

We expect in the first meter to find differences in the stratigraphy
depending mainly on the strength and efficiency of weathering effects
related to the local climatic regimes: deposition, saltation, and
aeolian processes. We expect also, depending on the latitude,
recondensation of volatile in the regolith pores. The presence of
cementation processes, if any, will also be detected as well as the
presence of salt.

Following MEPAG recommendations: *\"In situ analysis of surface and
subsurface soils and ices (to a few m depth) to search for gradients in
organic compounds (e.g., amino acids, proteins, carbohydrates, lipids,
nucleic acids, etc.) and to detect seasonal fluxes in carbon dioxide and
reduced gases (e.g. methane, ammonia, etc.)\",* shallow drilling will
permit to detect volatiles and carbon compounds gradients.

Also following MEPAG: \"*Determine the distribution of oxidants and
their correlation with organics**.** Requires instruments to determine
elemental chemistry and mineralogy.* *In situ experiments at one
targeted low latitude site and 1.0 meter depth to determine gradients in
the concentration of electrochemically active species at ppm
concentrations and susceptibility of metallic and organic compounds to
oxidation and to determine the spatial and* *depth distribution of
specific classes of oxidizing compounds (e.g., peroxides, etc.).* \"

***Deep drill***

As stated in the previous section, deeper penetration allow to increase
the number of key scientific questions to be addressed.

**Access to bedrocks:** recent observations have undoubtedly shown the
existence of extensive sedimentary processes,. Therefore it is difficult
to evaluate the depth at which bedrock can be found, depending on the
past and present climate conditions, the presence of surface or near
surface water, and the local geological structure. Deep penetration will
permit to quantify, locally, the intensity of the deposition,
sedimentation, and erosion phenomena.

**Access to ice and water:** despite of the large work of modelling
devoted to address the depth and distribution of cryosphere and
hydrosphere on Mars, many uncertainties are still present. The first
layers undergo to reworking and elaboration due to diurnal and seasonal
effects (temperature variation, sublimation and recondensation
phenomena, aeolian processes). Deeper layer can preserve records of
paleoclimatic condition as well as water and ice records (i.e
carbonates, that can be unstable on Martian surface). At larger depths,
hundreds of metres, the direct measures of ice and water can be
possible.

Measure of geothermal gradient: deep drill can allow to evaluate
geothermal gradient, both measure temperatures and geothermal heat flux,
as done on Terrestrial volcanic areas.

1.  [Instruments]{.underline}

The development of different instruments is strongly dependent on the
Drill configuration considered. In fact, a drill able to collect and
distribute samples will be associated with both in situ experiments and
with a small micro-laboratory able to perform detailed analyses on the
collected samples. In what follow, we report, as an example, the
instrument package selected for the 2003 NASA Lander mission. Obviously
other suites of experiments can be added depending on the Lander
resources and sharing between partners.

*The instruments here described, as well as the concept of the shallow
drill have been already studied, not only at laboratory level, but also
with selected Industrial Prime Contractors. The Phase A of the drill,
minilab and experiments* *has been already concluded, therefore the
breadboard of them can surely be ready in less then two years.*

> **MA_MISS (Mars Multispectral Imager for Subsurface Studies)**
>
> Ma_Miss is a miniaturized imaging spectrometer designed to provide
> imaging and spectra in VIS/NIR for studies of Martian subsurface
> layers. The instrument can be integrated into the drill and will be
> able to provide an image of a "ring", to determine the composition and
> granularity of different layers, and to identify the mineralogy of
> individual grains. Ma_Miss main objectives are:

-   Image the structure of the column excavated.

-   Identify the existence of "lateral anisotropy" on the ring walls.

-   Detect the presence of layers containing clays, carbonates and
    alteration products.

-   Identify the grain size distribution and grain structure at
    different depths along the walls of the hole.

-   Study the mineralogy of single grains through their spectrum.

> The data are acquired through a flat optical window on the drill wall:
> through this window the inner surface of the hole is illuminated by a
> different lamp. The image is acquired by an array of optical fibers
> simulating a slit. An optical system situated inside the drill will
> permit to observe details from few tenths of microns to hundreds of
> microns and to perform low resolution spectroscopy in the selected
> range. The linear array of optical fibers mimics the slit. The
> electronics design was focussed on miniaturisation of the electronic
> components and reduction of harness volume. Having identified the
> optical fibres as a critical item, a dedicated research has been
> carried out giving particular attention to the level of space
> qualification, looking for potential constructors.
>
> **IPSE (Italian Package for Science Experiments)**
>
> IPSE is a scientific autonomous micro-laboratory for Mars soil and
> environment analysis providing the capability to serve, handle and
> manage scientific miniaturised instruments accommodated inside its
> envelope. The IPSE concept has been developed by the CISAS group of
> the Padua University in strict co-operation with the prime contractor
> Tecnomare. A small robotic arm is stowed inside the envelope and
> provides the capability to deliver soil samples to the instruments
> from the Drill. Its general configuration is based on a structure with
> an external envelope to fit also the small lander. IPSE is designed to
> operate in Martian environmental conditions and for a lifetime of one
> Earth year with the aim to be upgraded at each launch opportunity. A
> modular philosophy has been implemented to allow the maximum level of
> de-coupling between IPSE and the experiments.

![](media/image38.jpeg){width="3.4244094488188974in"
height="2.2236220472440946in"}![](media/image39.pct){width="2.9799212598425195in"
height="2.2236220472440946in"}fig. 2.2-2 Robotic arm fig. 2.2-3 IPSE
Payload accommodation

It will feature the following main capabilities:

-   Autonomous thermal control.

-   Electrical interface with the Lander.

-   Communication interface with the Lander.

-   Control of the robotic arm for sample handling, sample collection
    from the drill, sample delivery and discharge to scientific
    instruments.

-   Sample preparation prior to analysis. In case of dusty or soft soil
    samples, the sample will be slightly compressed prior to measurement
    to reduce it to a proper layer.

-   Control of the micromechanisms for sample motions.

-   Processing capabilities, including housekeeping functions,
    scientific measurements scheduling and instruments power on/off,
    data acquisition, compression, temporary storage and transmission to
    the Lander.

IPSE includes the four scientific instruments here after described
(IRMA, MA-FLUX, MAGO, MARE-DOSE)

*IRMA (Infra Red Microscope Analysis)*

IRMA is a hyper-spectral microscope for the in-situ mineralogical
analysis of Martian samples. It works in the 1-5 μm spectral range, with
a spectral resolution of 8 nm. Its spatial resolution is 38 μm and the
overall field of view is compatible with the sample dimension collected
from the DEEDRI drill (12 mm diameter). The investigation carried out by
IRMA has the goal to quantitatively characterise the mineral and the
micro-physical properties of Martian subsurface samples. The in-situ
measurements have the considerable advantage with respect to remote
sensing observations of permitting an unprecedented spatial resolution
allowing removal of mineral identification ambiguities due to the
contamination of the spectroscopic features by the atmospheric gases and
aerosols. One of the main tasks of the experiment will be the assessment
of the present and past interactions among Martian surface materials,
hydrosphere and atmosphere through the study of the mineralogical
products of these interactions.

The industrial prime contractor is Officine Galileo, the same as for the
ESA-ROSETTA VIRTIS, involved in the project since the beginning. The
present plan of development foresees a prototype (breadboard) production
in the IAS CNR laboratory for the investigation of the critical
parameters (spectrometer temperature, spatial resolution, etc.) and for
the spectroscopic analysis of analogs samples of Martian soils. The
prime contractor will use the results to modify and optimise the
instrument design. The required models are then produced by the prime
contractor, while the PI shall retain responsibility over the scientific
calibration activity.

*MA_FLUX (MArs X FLUorescent Experiment)*

MA_FLUX will investigate the Martian surface using the X-ray
fluorescence technique, thus allowing the detection of the major and
trace chemical elements in the Martian soil, down to a few ppm, using
simultaneously the gamma scattering method and the X-ray fluorescence
technique. This instrument investigates the interior of samples to a
depth ranging between one mm and one cm. Furthermore it defines
precisely the X-ray absorption capacity of samples and permits the
estimation of the abundance of elements heavier than iron. By analyzing
the Compton and Raleigh scattered photons at different energies and at
different angles, it will be able to estimate the abundance of the major
elements. By analyzing the hard X-ray fluorescence features, this system
should evaluate the chemical composition of the trace elements within a
few ppm.

The MA_FLUX instrument is an Italian/French (CNR-IAS, Rome/Institut de
Physique du Globe, Paris) co-operation that sees CNR-IAS and
CEA/DSM/DAPNIA/Service d'Astrophysique as providing the instrument
concept and test, and an industrial part (Laben SpA ) that is
investigating the thermo-mechanical and electronics design.

*MAGO (Martian Atmospheric Grain Observer)*

MAGO measures cumulative dust mass flux and dynamical properties of
single intercepted particles as a function of time. It allows
determination of grain mass, size and shape distribution, and dynamic
behaviour of airborne dust. It is a single instrument including three
different detection sub-systems (three micro-balances using quartz
crystals as detectors of mass deposition, a grain detection system based
on the detection of the scattered/reflected light produced by the
passage of single grains through a collimated laser light "curtain", and
an impact sensor for the detection of the momentum released during the
impact of single grains on a sensing aluminium plate). These
measurements have never been obtained so far and will greatly improve
our capability to interpret and describe processes such as aeolian
erosion, redistribution of dust on the surface, transportation and
weathering, circulation and climate evolution. The measurements by MAGO
have a crucial role also in terms of the identification of hazards for
elements sensitive to dust deposition and, in a wider perspective, for
the human exploration of Mars. The MAGO sub-systems are similar to or
derived from concepts already developed for the GIADA, on board of
ESA-ROSETTA, therefore benefit from the development program already
carried on for this application.

The MAGO project is an international consortium including Italy
(Osservatorio Astronomico di Capodimonte, Istituto Universitario Navale
and University "Federico II" in Naples), Spain (Instituto de Astrofisica
de Andalucia, Granada) and United Kingdom (University for Space Science
of Kent). The hardware development is performed in collaboration with
Italian and Spanish industrial partners. Officine Galileo is responsible
for the overall management at industrial level.

*MARE-DOSE (MArs Radioactivity Experiment-DOSimeter Experiment)*

MARE-DOSE is an experiment for monitoring the β and the γ radioactivity
during the Earth to Mars cruise phase and at the surface of Mars, in the
range 30-300 keV. It consists of lithium-fluoride doped pills which can
be exposed to the radiation, reset and readout by heating the pills
within a thermo-luminescent process during heating cycle and the
emission of an optical signal flux proportional to the absorbed dose.

The DOSE instrument will be realised with a Italian effort of scientific
institutes and national space industries. The preliminary phase of
design of MARE-DOSE and the subsequent manufacture and tests of the DM
are under the responsibility of research institutes (CNR and Perugia
University) with the contribution of technical aspects from industry.
During the Development Phase the hardware and management activities
concerning all the deliverables (will be carried out under industrial
control, with researchers retaining control over scientific requirements
and performances definition. The test activities on the DM will continue
in the research institutes, thus providing useful input for the detailed
design of the experiment. This approach will allow considerable
reduction of costs, while ensuring that the instrument will meet the
scientific requirements imposed during the design phase as well as the
overall mission design. At present, the detector has been defined
together with the power supply and data acquisition system. A mechanical
and optical architectural design has been developed considering the
possible locations within IPSE. A model for the thermal analysis has
been implemented for the operation phase and for survival during the
cruise phase, and a preliminary electronics architecture has been
designed.

**Increase of Science Related to sample collection.**

The collection and examination of sample will greatly increase the
overall scientific return of the drilling activity. In fact, as
previously stated, the measurements that are possible in the drilled
hole are limited due to the restrictions in size and power imposed by
the drill itself: The sample collection and distribution to microlabs
will permit to perform several measurements also including those
requiring sample destruction (see for example HEDS proposed
measurement). Moreover the measurement in the drilled hole shall not
interfere with the main drill functionality.

###### DEEP DRILL Configuration

Deep drill concepts could probably not allow the sample delivery due to
the completxity of such an operation; nevertheless deep drill concepts
can include the Ma_Miss and the already mentioned Temperature, Thermal
Flux, Diffusivity and Radioactivity sensors. The main purpose of the in
situ measurements will be to identify the main characteristics of the
local environment with the minimum alteration. Moreover the removal of
the complex mechanisms needed to collect the samples, will permit to
achieve deeper penetration. Therefore it is strongly suggested to couple
the two different concepts, if feasible.

# **DRILLING ENGINEERING**

## [Mars Environment information]{.underline}

Mars data useful to the study:

-   Pressure average 6.36 mbar

-   Gravity 3.71- 3.758 m/s^2^

-   Temperature range 140 to 300 K

-   Atmosphere composition CO~2~ 95.3%

> N~2~ 2.7%
>
> Ar 1.6%
>
> O~2~ 0.1%
>
> CO 0.08%
>
> Remainder trace gases

The geology of Mars is variable based on the location, and can only be
assumed for the depths that are targetted for the current drilling
proposals. For the study and in absence of clear design data the
following assumptions have been made:

Unconsolidated overburden Sand or dust

Regolith

Consolidated rock Shale or cemented sandstone

Hard rock

## 

## [Assumptions on spacecraft available resources]{.underline}

> The following design cases have been considered based on the
> information received by email:

  ----------------------------- ----------- ----------- --------- ---------
                                Case 1      Case 2      Case 3    Case 4

  Mass, kg                      100         100         150       50

  Day Energy, w-hr              200         220         600       200

  Peak Day Power, w             TBD         TBD         TBD       TBD

  Night Energy, w-hr            75          220         600       75

  Peak Night Power, w           TBD         TBD         TBD       TBD

  Mission lifetime (yrs)        0.3         3           3         0.5
  ----------------------------- ----------- ----------- --------- ---------

> Lander/Rover mass assumptions: Large Lander: 1100kg; Large Rover:
> 750kg; Modest Lander: 750kg.
>
> Schedule:

-   Feb 2003 Lander concept selection

-   Feb 2004 Lander PDR

-   Feb 2005 Lander CDR

-   Aug 2006 Delivery of drill flight system to ATLO

-   Sep 2007 Launch

## [Drilling concepts and impacts on spacecraft]{.underline}

> In this chapter different drilling concepts are presented:

-   **Drill Tool concept:** this approach is based on traditional drill
    technology and is targeted to a depth of about 2 meters. It allows
    sample acquisition (in form of cores if allowed by the material
    properties) and distribution to scientific instruments for in-situ
    analysis;

-   **Coiled Tubing Drill:** this alternative utilises a riser/conductor
    unit for the penetration into unconsolidated overburden, a coiled
    tubing drill string for boring the hole and a compressed gas lift
    system for removing the drill cuttings from the hole during
    drilling. It can reach a depth of some tens of meters and it allows
    the sample collection;

-   **Hollow stem Auger Drill:** this solution utilises a drill string
    deployed from a drill frame and made up of a number of flighted
    tubing joints to permit the removal of drill cuttings. It can reach
    a depth of about 20m and it allows the sample collection by using a
    suitable sampling tool (gravity deployed) to be inserted into the
    borehole periodically;

-   **Worm concept:** this solution utilises high frequency vibrations
    or rotary drilling/cutting tools to progress the bit through the
    soil, utilising barbs or tracks to put axial pressure on the bit. It
    does not allow sample collection.

### Drill Sampler Tool concept

#### Concept Description and Performances

The Drill Sampler Tool (DST) concept has been studied by Tecnospazio,
under direct guidance of ASI, as a multipurpose tool to be used in
different space missions. In fact a similar sampler device has been
already developed for the Lander of the Rosetta mission. The original
Drill Sampler Tool, during the assessment and the Phase A, was modified
in order to be used as a real scientific system. In fact, after the
selection of the experiments to be housed in the drill, the drill
mechanical structure and its electronics were changed accordingly.
Moreover it was also foreseen to calibrate the drill torque/force in
order to use it as a tool to characterise soil mechanical properties.
The scientific team, therefore, was also involved in the definition of
the new drill configuration. This concept has been proposed by ASI to
JPL for the missions 2003 and 2005; in that occasion the system was
named DeeDri.

The concept is based on a particular drill tool featuring sampling
capability as well, as described hereafter.

Description of basic tool operation

+-----------------------------------+-----------------------------------+
| ![](media/image41.pct)            | > The baseline tool schematics is |
|                                   | > shown in Fig. 3.3.1.1-1; it     |
| **Fig. 3.3.1.1-1 - Drill tool     | > includes:                       |
| schematics**                      | >                                 |
|                                   | > > • main tube with external     |
| **(no scientific instrumentation  | > > auger, provided with cutting  |
| is shown)**                       | > > bits.                         |
|                                   | >                                 |
|                                   | > • central piston, rotating      |
|                                   | > together with the external      |
|                                   | > auger; it can be uplifted upon  |
|                                   | > command so to create a volume   |
|                                   | > available for sample housing;   |
|                                   | > it is also provided with        |
|                                   | > cutting bits.                   |
|                                   |                                   |
|                                   | • shutters, which can be          |
|                                   | activated upon command and have   |
|                                   | the purpose to both detach the    |
|                                   | root of the sample from the soil  |
|                                   | and contain the sample (either    |
|                                   | solid or powder). The shutters    |
|                                   | can be activated only when the    |
|                                   | central piston is uplifted and a  |
|                                   | sample (e.g. core) is contained   |
|                                   | in the dedicated volume.          |
|                                   |                                   |
|                                   | > • actuators, to move the        |
|                                   | > central piston and the          |
|                                   | > shutters.                       |
|                                   | >                                 |
|                                   | > Different drill tool diameters  |
|                                   | > can be implemented; for example |
|                                   | > in the system already proposed  |
|                                   | > for the 2003 mission it was 35  |
|                                   | > mm, allowing the collection of  |
|                                   | > core samples of 14 mm diameter, |
|                                   | > 25 mm length and also allowing  |
|                                   | > the incorporation of scientific |
|                                   | > sensors inside it.              |
+-----------------------------------+-----------------------------------+

In order to describe the sequence of operations of the drill tool,
reference is made to Fig. 3.3.1.1-2.

-   The sequence starts as showed in sketch 1, with the drill tool in a
    normal drilling configuration, i.e. the central piston is in drill
    position and the shutters are (necessarily) open;

-   in order to start a sample acquisition, the drill tool is arranged
    as in sketch 2: the central piston is uplifted and the shutters are
    still open;

-   the drilling action is then continued to perform actual coring till
    the filling of the sample volume, as shown in sketch 3;

-   the shutters are then commanded to close, while the drill tool still
    rotates, so that a core sample is detached from the soil and fully
    encapsulated in its container, as shown in sketch 4;

-   the drill tool leaves the bore hole and brings the collected sample,
    as in sketch 5

-   finally, the sample is discharge into the container, sketch 6.

The system can collect samples starting just below the surface up to the
maximum depth that depends on the drill tool length. The collected
samples can either be directly discharged into the ports of scientific
instruments for in situ analysis or, if required, stored in dedicated
sample containers, for example mounted on carousels. Such sample
containers can be transferred in a second time to other instruments or
to a transfer vehicle for return to Earth.

![](media/image42.pct)

**Fig. 3.3.1.1-2 - Sample collection and discharge sequence**

***Drill Unit***

+------------------------------------------+---------------------------+
| The drill unit contains all mechanisms   | !                         |
| necessary for actuating the              | [](media/image43.png){wid |
| drilldrilling, collecting samples and    | th="2.5493055555555557in" |
| delivering samples to the instruments or | heigh                     |
| storing the samples in samples           | t="2.7215277777777778in"} |
| containers, if required. The drill unit  |                           |
| schematics is shown in Fig. 3.3.1.1-3,   | **Fig. 3.3.1.1-3 - Drill  |
| key elements are the following:          | unit schematics -**       |
|                                          |                           |
| -   Mechanical structure, for structural | **base configuration**    |
|     support, housing and general         |                           |
|     protection; it contains the drill    |                           |
|     tool as well as translation and      |                           |
|     rotation group mechanisms;           |                           |
|                                          |                           |
| -   drill tool, with sampling capability |                           |
|     and provision for scientific         |                           |
|     instruments and local sensors        |                           |
|     allocation (e.g. camera for          |                           |
|     stratigraphy, temperature sensors);  |                           |
|                                          |                           |
| -   drill related mechanisms and         |                           |
|     sensors: rotation group (i.e.        |                           |
|     motor-gearbox, rotation sensor and   |                           |
|     torque sensor), translation group    |                           |
|     (i.e. motor plus gear, translation   |                           |
|     sensor and vertical thrust sensor),  |                           |
|     translation guides;                  |                           |
|                                          |                           |
| -   carousels, if required, for sample   |                           |
|     containers accommodation and         |                           |
|     relevant actuation and control       |                           |
|     components;                          |                           |
|                                          |                           |
| -   loader device, if required, for      |                           |
|     transfer of sample containers;       |                           |
|                                          |                           |
| ```{=html}                               |                           |
| <!-- -->                                 |                           |
| ```                                      |                           |
| -   TV camera (not shown in the          |                           |
|     picture).                            |                           |
+------------------------------------------+---------------------------+

*Depth*

Drilling and sample acquisition depth depends on available Drill Unit
dimensions; it could be from 0.5-0.8 m in case of a single rod drill
tool to few meters using extension rods. Figures 3.3.1.1-4 shows a
possible multi rod drill unit(3rods).

+---------------------------------------------+------------------------+
| ![](media/image44.pct)                      | Main elements:         |
|                                             |                        |
|                                             | • Drill Tool:\         |
|                                             | performs drilling by   |
|                                             | cutting,\              |
|                                             | incorporates sample    |
|                                             | acquisition mechanism; |
|                                             |                        |
|                                             | -   Drill Carriage:\   |
|                                             |     rotates the Drill  |
|                                             |     Tool,\             |
|                                             |     applies            |
|                                             |     translation        |
|                                             |     thrust;            |
|                                             |                        |
|                                             | -   Extension Rods\    |
|                                             |     (with soil         |
|                                             |     cuttings transport |
|                                             |     auger);            |
|                                             |                        |
|                                             | -   Extension          |
|                                             |     Mechanism:\        |
|                                             |     performs           |
|                                             |     as                 |
|                                             | sembling/disassembling |
|                                             |     actions with       |
|                                             |     Extension Rods     |
+---------------------------------------------+------------------------+

*Downhole science and sensors*

DST system allows the accommodation of sensors as described in para 2.
Also, the Drill Unit can install a TV camera at its lower face. The
images provided by this camera can be analysed on ground to allow the
identification of a suitable drilling location, including parameters
such as the three co-ordinates of the drilling point, the local surface
inclination (w.r.t. Lander balcony), the soil morphology in the
surrounding of the drill location. Furthermore, the TV camera could
support the sample discharge operations and general inspection
activities.

Thrust/force measurement sensors and temperature sensors can be
installed to exploit the drilling functions to characterise the soil
during drilling.

*Accommodation and Mobility*

The DST can be accommodated either on the lander or on the rover.

A possible accommodation on the lander is schematically shown in Fig.
3.3.1.1-5 (stowed configuration during launch) and Fig 3.3.1.1-6 (DST in
drilling/sample collection configuration). The Drill Unit is moved to
the surface by means of a Positioning Unit so that it is possible to
drill at different locations. The complexity of the Positioning Unit
depends on the lander characteristics such as the distance from the deck
to the soil surface, the volume available for stowage of the entire
system, the required drilling area, etc. As an example, for the DST
proposed for 2003/5 missions (DeeDri) the positioning unit was a
manipulator arm of 4 degrees of freedom. Simpler positioning units are
possible if no major constraints are put on the room available for
accommodation during launch and its definition is done very soon
together with the lander one.

Fig. 3.3.1.1-7 and Fig. 3.3.1.1-8 sketch the DeeDri layout in a typical
deployed position and in the drilling configuration, respectively.

Figure 3.3.1.1-9 shows a possible accommodation of the DST on a rover.

+------------------------------------+---------------------------------+
| ![](media/image45                  | ![](media/image46.pn            |
| .png){width="3.2583333333333333in" | g){width="2.9451388888888888in" |
| height="2.2875in"}                 | height="2.2819444444444446in"}  |
|                                    |                                 |
| Fig. 3.3.1.1-5 -- DST stowed       | Fig. 3.3.1.1-6 - DST deployed   |
| configuration\                     | configuration\                  |
| (launch/landing phase)             | (drilling phase)                |
+------------------------------------+---------------------------------+
|                                    |                                 |
+------------------------------------+---------------------------------+
| ![](media/image47.pct)             | ![](media/image48.pct)          |
|                                    |                                 |
| > Fig. 3.3.1.1-7 DeeDri layout     | **Fig. 3.3.1.1-8 - Drill        |
| > schematics                       | positioning on soil**           |
|                                    |                                 |
| (deployed configuration)           | **(drilling configuration)**    |
+------------------------------------+---------------------------------+

*On Rover:*

![](media/image49.pct)

Figure 3.3.1.1-9 DST accommodation on the Rover

####  [Characteristics]{.underline}

The mass of the DST depends on the number of drilling rods and the
functions implemented (i.e presence or not of the carousel for storage
of samples, type of positioning unit etc....). The current estimate is
that the complete system mass in multi-rod configuration can be less
than 50kg, therefore it can be accommodated in all 4 cases.

Dimensions of the system depend on the functions implemented; as an
example a DST similar to the DeeDri system could be accommodated in an
envelope of ca. 1000mm x 300 mm x 300mm (excluding electronic unit).

Power consumption, thrust and torque required by the DST depends on the
characteristics of the soil; some figures based on prototype tools of
different diameter tested at Tecnospazio with "Travertino" material (of
medium-high compressive strength) are shown here below.

  ---------------- -------- --------------------- -------------------------
  Tool diameter    Thrust   Vertical speed        Input power to drill
  (mm)             (N)      (mm/minute)           rotation motor

  32               150      2.0                   28

  12               100      2.0                   5
  ---------------- -------- --------------------- -------------------------

To derive a possible system operation profile it has been assumed (based
on internal data available of electronic power consumption and
efficiency) that the input power to the system is 60-65W in case a drill
tool of 32mm of diameter is drilling into a material whose
characteristics are similar to travertino.

![](media/image50.pct)

Figure 3.3.1.1-10 -- Example of Operations

####  [Technological evaluation]{.underline}

Advantages:

-   conventional technology already proved, design can be tested
    on-ground,

-   uniformed acquired samples independent of soil properties -
    facilitates sample handling

-   known acquisition depth, minimal cross-contamination

-   able to cope with all types of soil (soft, hard, unconsolidated)

    Disadvantages:

-   limited depths

Drill Tool technology (PCD) has been largely evaluated in research and
application programs leaded by Tecnospazio for ASI and ESA; this
includes:

-   the *Drill, Sample and Distribution* system developed for the
    Rosetta Lander by Tecnospazio under an ASI contract; this is a
    compact system (mass\<4kg) capable of collecting small samples to a
    depth of 0.5meter and deposit them into dedicated containers (ovens)
    mounted on a carousel for subsequent delivery to the scientific
    instrument for analysis;

-   the *Comet Nucleus Sample Return --Sample Acquisition System*
    developed for ESA where a large corer tool (diameter\>100mm, length
    \>1meter), a surface tool and an anchoring system were developed;

-   the *Small Sample Acquisition and Distribution Tool:* a compact
    system(mass ca 1.5kg) capable to collect surface samples and
    distribute them to the scientific instrumentation, developed for
    ESA.

All devices developed in the above mentioned programs were tested in
thermal vacuum at LN~2~ temperature.

The prototype tools for DST developed by Tecnospazio and tested at
ambient conditions.

### Coiled Tubing Drill

1.  [Concept description and capabilities]{.underline}

#### 

The Coiled Tubing Drill (CTD) is a compact and suitably adapted version
of the coiled tubing drilling systems that are currently available as
terrestrial drilling systems. The system is based on the use of a
riser/conductor unit for the penetration into the unconsolidated
overburden, of a coiled tubing drill string for boring the hole, and of
a compressed atmospheric gas lift system for removing the drill cuttings
from the hole during the drilling

From initial conservative dimensioning it has been established that a
depth of around 20 metres can be achieved without the risk of exceeding
the basic mass, energy and time constraints (100 kg and 200 w-hr),
although greater depths may well be feasible following more in depth
design. In particular for the constraints of Case 3 depths up to 50
metres are considered to be feasible. The concept is therefore to be
regarded as an intermediate depth solution, with the advantage of
ensuring the collection of both data and samples through an
unconsolidated overburden and through a hard rock. In particular this
solution shall not be jeopardised by the presence of rocks with very low
porosity that may block solutions that do not foresee the removal to
surface of the drill cuttings.

The concept is based on state-of-the-art technology and therefore shall
require a relatively minimum amount of development, principally tied to
downscaling from 3 inches to 2 inches of many of the tubing components
for Cases 1, 2, and 4, while Case 3 shall permit the use components with
the same dimensions as those already developed. Use of lightweight
materials such as Aluminium alloys and Titanium should however be
considered to minimize mass. It is probable that further development
shall also be necessary for the control and automation of the system.

Fig. 3.3.2.1-1 Schematics of Coiled Tubing Drill

The system is made up of the following main units:

**Riser/conductor unit**: The riser shall have the aim of extending the
bore from the soil surface to the drill system location on the lander,
while the conductor shall be lowered during surface drilling in the
unconsolidated surface overburden and provide stable hole walls down to
the depth where the soil becomes consolidated. The riser shall act as a
carrier tube and have one or more spool pieces joined to the conductor
situated within it in a telescopic configuration. The upper end of the
riser shall provide for the introduction of the coiled tubing through a
tube wiper, and shall also provide for the removal of the drill cuttings
to a suitable location through an exhaust lift gas diffuser. Preliminary
dimensioning of the hole for optimum energy and mass characteristics has
given a hole external dimension of 8 cm, for 20 m drilling depth, and 11
cm, for 40 m drilling depth, therefore the dimensions of the risers and
conductor tubes shall be such as to provide this, based on the number of
concentric tubes used.

**Coiled tubing system**: The drilling system itself shall be made up of
the reel, the reel electric motor that shall both unwind the tubing from
the reel and provide pressure on the drill bit, the tube straightener
rollers, and the drill string. The drill string shall be composed of a
number of different components used in the Oil and Gas Industry, the
principal ones being: Drill bit; electric downhole motor; downhole
orienter (optional); downhole science instrumentation based on
Measurement While Drilling (MWD) techniques; and the tubing itself,
which shall contain an electric cable to provide power to the downhole
motor and return downhole science data to the surface. The tubing shall
have a diameter of around 5 cm, while the length shall be based on the
target depth and the actual mass and dimensions allowed.

**Gas lift compressor**: The system for removing the drill cuttings
shall be made up of a small compressor, typically 500 cm^3^ capacity (or
1000 cm^3^, for 40 m depth) that shall utilise the Martian atmosphere to
pump compressed CO~2~ down the hole through the coiled tubing, through
the drill bit and then remove the cuttings to the surface through the
annular area between the hole walls and the tubing itself. Detailed
calculations have indicated that for soil particles up to 2 mm the
dimensioning of the compressor shall be within both traditional
technology and the power available.

**Calculations**

The dimensioning of the system has been based on the design data
indicated in chapter 3 and in particular the base case mass of 100 kg
and energy of 200 w-hr (as defined in Cases 1 and 2) have been used as
the reference data, following which number of assumptions and an
iterative calculations have been performed to identify the best solution
for the resources available. The main assumptions and results of the
calculations are indicated in the following.

> Atmospheric Temperature 273 K (almost worse case assuming daytime
> work)
>
> Particles (drill cutting) Diameter 1 mm
>
> External bore Diameter 80 mm
>
> Internal tubing Diameter 53 mm
>
> Internal tubing thickness 0. 5 mm
>
> Particle lift speed 2 m/s
>
> Bore length 20 m (base case)
>
> 40 m (extended case)
>
> Riser/conductor length 1.5 m
>
> Riser/conductor diameter 90 mm

Gas Lift compressor: In order to verify the feasibility of the gas lift
compressor system described above, a detailed dimensioning study has
been performed. The calculations, which have indicated both the
feasibility of the concept and the suitable dimensioning of the
components required, have been performed taking into consideration the
following factors:

-   Flow pressure drops both within the coiled tubing and in the annular
    area have been calculated with a friction coefficient corresponding
    to the actual Reynolds number (laminar to transition regime),
    verifying that the expansion throughout the complete circulation
    remains within the subsonic regime.

-   Viscosity, density and specific heat capacity have been calculated
    as functions of the surface pressures and temperatures indicated in
    the listing above.

-   The minimum flow velocity has been calculated to guarantee a net
    lift velocity of the solid particles of 2 m/s with particle
    diameters of 1 mm, with a drag coefficient calculated for laminar
    flow as a function of the particle Reynolds number. (Cd≥1.2) The
    assumed lift velocity is such to guarantee the removal of the chip
    particles at a greater rate than that at which it is generated by
    the cutting tool, leaving a suitable margin in case of additional
    particles being provided because of unconsolidated soil conditions.

-   Compression power has been calculated considering a polytropic ideal
    gas compression, starting from the atmospheric conditions, and
    delivering at the calculated required total back pressure.

-   For each depth considered in the sensitivity study, the optimum
    diameters for the coiled tubing and the annular area have been
    derived to minimise the power required for the lift velocity
    assumed.

For the base case data above and considering an overall efficiency for
the driver of 0.5, a compression polytropic efficiency of 0.8, a
volumetric efficiency of 0.9, the power requirement is about 60 W, for a
pressure ratio of 1.42. A volumetric compressor may suitably satisfy the
derived flow and compression ratio conditions, with a half litre swept
volume for the base case, and a litre swept volume for the extended
case.

A series for sensitivity analyses have been performed around the base
case data, with the following main indications:

-   For lower atmospheric temperatures the power consumption is reduced
    (e.g. for 200 K power requirement is 50 W)

-   For smaller bore diameters there is a power saving (reduction of 25%
    in bore diameter give an 8% reduction in power), although component
    development shall have to be closely monitored.

-   Particle diameter has a significant effect on the power
    requirements, with 0.5 mm particles reducing power requirements to
    around 35 W

For the Case 3 resources (150 kg and 600 w-hr), the sensitivity analysis
has indicated that 40 metres depth can be achieved, increasing the
diameter of the hole to 110 cm and of the tubing to 7.5 cm. This shall
ensure that the gas flow remains unchoked (subsonic).

Calculations have also been performed to verify the drill rate that a
bit of the size indicated can achieve in these conditions. Utilising the
results of the tests performed by Tecnospazio on its drill bits, the
worse case drill rate is given while drilling into basalt and depending
on the energy available shall give from a minimum of 1.25 cm/day for
Case 1 to a maximum of 3.75 cm/day for Case 3. It can be noted that at
these drill rates it is not necessary to contemporarily drill and
circulate the compressed gas. In hard rock the work cycle can be 1 min
of drilling followed by 20 seconds of gas lift.

**Operations**

The operations shall be based on operating from the lander rather than
the rover. The drilling system shall be fixed to the lander in such a
way as to simplify the handling of the equipment (see conceptual
drawing): the riser/conductor unit should be placed in a vertical or
near vertical position (in the event that this is not feasible a hinged
mechanism to move the riser/conductor unit from horizontal on the lander
platform to vertical from the platform to the surface shall be
included); the coiled tubing reel and accessories shall be placed
horizontally on the lander platform in a position that shall not require
it to be repositioned for the operations.

The basic operating method shall be as follows:

1.  The riser is lowered from the lander until it is contact with the
    surface

2.  The coiled tubing presses down on the surface, bringing the
    conductor with it.

3.  Drilling is commenced with the gas lift actioned to remove
    unconsolidated soil.

4.  The conductor follows into the hole until consolidated soil is
    encountered. The drill and gas lift are powered together in this
    phase but requirements for both shall be limited until consolidated
    soil is met.

5.  Drilling continues into the rock without the conductor that is
    stopped by the rock. The reel traverses along its guides to ensure
    the coiled tube is introduced tangent and vertically into the riser
    head.

6.  Gas lift alternates with the drilling to remove drill cuttings.

7.  Periodic sampling is taken at the surface at the top riser diffuser
    (e.g. by latch able small samplers(capsulae) .

**Capabilities**

*Depth*

A depth of 20 m can be safely specified with this technology. For Case 1
the critical factor for this case shall be the mission life, as if the
rock is very hard then the depth that can be obtained in the 4 month
mission life is in the order of 20 metres. For the mass and energy
resources of Case 3 a depth of 40 metres can be achieved.

Further detailed design may indicate that greater depths are feasible,
with the power consumption being the critical factor. However within a
three-year mission life the available energy can be concentrated to
shorter working periods. It should be noted that for the gas lift, a
driver power of around 120 W is required to remove drill cuttings from
40 metres.

For Case 4 the mass budget may be the critical item, although the mass
dimensioning has been conservative and to provide the system within the
50 kg mass is considered feasible.

*Sampling*

The CTD is suitable to sampling as the gas lift removal of drill
cuttings provides a constant flow of downhole material to the surface.
The principal limitation shall be the fact that an interlayer soil
samples contamination may occur and that these samples shall be drill
cuttings and not a core. Controlling undisturbed downhole temperature
for ice and hydrocarbon samples shall also not be a feature of this
solution.

*Downhole science*

Drilling on a continuous tube that is connected to the surface with an
electrical cable is a possible solution for downhole science. In this
case many of the components needed for logging have already been
developed for similar tubing sizes.

*Mobility*

Due to the mass and dimensions of the solution, it has been assumed that
it shall be located on the Lander. In the event that localisation on the
rover is feasible, the advantage shall be to locate the drilling system
on a suitable surface, both as regards overburden and rock hardness.
Basically the major risk for the designed CTD is if unconsolidated soil
extends more than a couple of metres from the surface. Mobility could
ensure that a consolidated surface is found as the site of the bore.

####  [Characteristics]{.underline}

On the basis of the calculations performed the following budgetary
masses and dimensions have been identified for the base case solution
for drilling to 20 metres:

  -------------------------- ----------------- --------------------------
  **Component**              **Mass (kg)**     **Dimensions (m)**

  Coiled tubing:             12                20 x 0.001

  Reel unit:                 15                0.5 x 0.6 x 0.6

  Gas compressor:            3                 0.1 x 0.2 x 0.1

  Riser/conductor unit:      8                 1.5 x 0.09 diameter

  Control Pod                2                 0.1 x 0.2 x 0.1

  Ancillaries:               15                \-

  **Total:**                 **55**            **1.5 x 0.6 x 0.6**
  -------------------------- ----------------- --------------------------

####  [Technological evaluation]{.underline}

The principal advantage of this system is that it guarantees the
advancement of the hole even if the porosity is very low and therefore
other systems that do not foresee drill cuttings removal would become
stuck. The system can drill to a depth that is further than typical
borer technologies, but shall not be able to attain the hundreds of
metres which may be the ambitious target for a mission.

The coiled tubing equipment has become relatively standard in the oil
industry and therefore most of the components, control systems and
experience with the procedure are already available for downscaling to
the requirements to the mission. Generally coiled tubing components are
produced in 3 inch or 3.5 inch sizes, therefore the downsizing required
shall be contained. Mostly the step on will be in the selection of
suitable light materials.

An aspect to be carefully considered shall be the plastic straightening
of the coiled tube in the operating temperatures, in order to ensure
that cryogenic embrittlement does not lead to failure of the tubing. It
should be noted that all tube straightening shall take place at the
surface when the coil is spooled out of the reel, and that ground
temperatures during the 8 hour operational window (above 250 K) during
the day should be above the temperature rating of the current materials
used for coiled tubing operations that are carried out in arctic
regions. However if specified operational temperatures are lower, a
number of specific solutions may be adopted: firstly material selection
may be performed to privilege cryogenic characteristics and thus widen
the operational range; secondly if the temperature ranges specified
remain outside the capabilities of the applicable materials, local
heating in the limited area in which straightening occurs can be
considered. This may be performed by providing a heating sleeve, which
need not be longer than a few centimetres, and containing a resistance
to provide the heat source.

Operational risks shall be associated to the type of geology
encountered, and in particular if the unconsolidated soil extends to
great depths. In this case the limited conductor length shall mean that
the hole walls may collapse on the drill string and not permit great
depths to be achieved.

### Hollow-stem Auger Drill (HAD)

####  [Concept description and capabilities]{.underline}

The Hollow-stem Auger Drill (HAD) is a compact and suitably adapted
version of the auger drilling systems that are currently available as
terrestrial drilling systems. The system is made up of the following
components:

-   A drill frame and base, that shall be connected to the lander;

-   An electric motor and transmission system connected to the rotary
    box, which drives the spindle;

-   The drill string made up of a number of lengths of hollow-stem auger
    and a bit.

-   An automated pipe handling system for making up the drill pipe.

-   A sampling reel that shall introduce downhole sensors and samplers
    periodically down the centre of the auger

HAD drilling is an ideal method for drilling without the need for a
fluid to remove drill cuttings, which are recovered by employing
flighted tubing and rotation. The capabilities of the technology exceed
over 100 metres in terrestrial drilling and are considered to be
suitable up to 20 metres, remaining within basic resources available: as
previously design work has been performed utilising 100 kg and 200 w-hr
as the base data. HAD drilling is particularly applicable for drilling
through unconsolidated sands, silts and clays, and also is capable of
drilling through soft rock, depending on the spindle torque that can be
applied. The system maintains the integrity of the bore hole even in
un-consolidated soils and facilitates well sampling.

Fig. 3.3.3.1-1 Schematics of Hollow-stem Auger Drill

####  [Characteristics]{.underline}

On the basis of the calculations performed the following budgetary
masses and dimensions have been identified for the base case solution
for drilling to 20 metres:

  -------------------------- ----------------- --------------------------
  **Component**              **Mass (kg)**     **Dimensions (m)**

  Frame and base:            15                2 x 0.4 x 0.2

  Power & transmission unit: 10                \-

  Pipe rack & pipes:         40                1.7 x 0.2 x 0.2

  Pipe handling unit:        6                 \-

  Sampling reel & tools      4                 0.1 x 0.2 x 0.1

  Ancillaries:               15                \-

  **Total:**                 **90**            **2 x 0.6 x 0.6**
  -------------------------- ----------------- --------------------------

####  [Technological evaluation]{.underline}

The HAD systems main advantage is that it provides a relatively simple
drilling system, without the use of casing and fluid circulation, while
maintaining the capability of being able to sample and monitor
throughout the depth of the hole. This technology is particularly suited
to drilling in un-consolidated soil and soft rock, and therefore its
major drawback shall be that it cannot guarantee to reach a set depth,
unless the geology of the drill site is known.

Other limitations for the use of HAD on Mars shall be the limited power
available, which may limit the depths that can be achieved in very loose
soils, in which the auger shall be loaded significantly from the
surrounding soil and not just from the transport of cuttings from the
drill bit.

Technology risks associated with the solution are considered relatively
low due to the maturity of the technology involved, in particular for
the drill components. Nevertheless, significant development work shall
have to be carried out for the automation of the system, in particular
for the pipe handling system, even though in the field of large rotary
mud drilling within the oil industry automatic pipe handling systems
have been developed.

### Worm concept

####  [Concept description and capabilities]{.underline}

The worm solution is based on the use of high frequency vibrations for
the penetration of a probe into the soil. The solution is based on the
vibration technology used for driving piles, particularly in the
offshore industry, as well as the current development of a
piezoelectrically actuated ultrasonic drill being performed by JPL and
Cybersonics. The probe shall be made up of a drill bit that is mounted
on a cylindrical container that provides the vibration actuators. A set
of articulated chain tracks or alternatively radial barbs shall provide
weight to the bit and permit the probe to advance through the bore.
Energy is supplied from the surface via a wire that is released from the
probe as it advances. This action of deploying the wire out from the
worm itself shall ensure that the wire shall not have to be pulled
through the hole, which in unconsolidated or incohesive soils would
limit the depth that can be achieved. A deployment system shall be
located on the Lander or the Rover to permit the probe to be introduced
into the topsoil.

The capabilities of this system are potentially to reach significant
depths, with the limitations coming from either the length of the wire
spool placed on board, or the conditions of the rock. Although the
solution is capable of drilling through extremely hard materials, the
worm may have difficulty in proceeding through incohesive rock, as no
material removal is foreseen. . Suitable drill cuttings shift from the
fore to the back end of the tool must be provided.

Fig. 3.3.4.1-1 Schematics of Worm concept

**Operations**

The worm probe shall be well within the mass budget of all 4 Cases, and
therefore it may be placed on either the Lander or the Rover. In the
event of it being placed on the Rover, operations shall commence once a
suitable site for drilling has been located. The deployment system shall
lower the worm from the Lander or Rover platform, down to the surface.
Once the vibrations of the bit are actuated, pressure shall be
maintained by the deployment system, until the probe has penetrated the
soil to its full length. This shall permit the articulated chain tracks
or radial barbs to maintain pressure on the bit. The articulated chain
tracks shall be self cleaning and function much as caterpiller tracks
do, while the radial barbs shall function as follows: they are deployed
to engage the walls of the hole; drilling commences and pressure is kept
on the bit as the barbs are forced toward the rear of the worm; once the
barbs have completed their stroke, drilling is suspended while the barbs
are retracted within the cylinder of the worm, stroked back to the
front, and then redeployed to permit a new drilling sequence. During the
progress of the worm, the control wire shall be deployed out of the rear
end from a self deploying spool that shall require no active components.
Retrieval of the worm has been considered but has not been included in
the design performed to date, therefore the worm shall continue to drill
until either the control wire reaches the end of its length, or the
worms progress is halted by the rock conditions.

**Capabilities**

**Depth**

The worm solution shall potentially permit great depths to be achieved.
Preliminary dimensioning has aimed at a system for 1000 metres, with the
size of the control wire reel becoming the dimensioning component.

**Sampling**

Although with drilling direction control it may be feasible in the
future to consider a worm that can be retrieved to the surface, the
current design does not foresee this. For this reason down hole sampling
is not a feature of this solution.

**Downhole science**

Downhole science shall be available by including dedicated sensors in
the worm. Continuous data gathering shall be available due to the
control wire that connects the worm to the surface.

**Mobility**

Due to the dimensions and mass of the worm and its deployment system,
its location on the rover is feasible and shall permit a optimum site
for its operation.

####  [Characteristics]{.underline}

On the basis of the calculations performed the following budgetary
masses and dimensions have been identified for the worm:

  -------------------------- ----------------- --------------------------
  **Component**              **Mass (kg)**     **Dimensions (m)**

  Worm:                      20                0.5 x 0.15 diameter

  Deployment system:         15                0.7 x 0.3 x 0.3

  Control pod:               3                 0.1 x 0.2 x 0.1

  **Total:**                 **38**            
  -------------------------- ----------------- --------------------------

####  [Technological evaluation]{.underline}

The worm solution has the advantage of potentially being able to drill
to very deep depths, while remaining within the resources available for
the 4 cases defined. It is applicable to a wide range of soil
conditions, with the only limitation being from an extended layer of
rock with very low porosity, which could halt its progress.

The main innovation of the system shall be the high frequency vibration
equipment and its chips handling and local motion. However it should be
noted that systems of this kind are not currently developed, and thus
the technological risk for all the system shall be higher than for the
solution discussed so far.

## [SUMMARY AND CONCLUSIONS]{.underline}

The paper has identified four basic alternatives to the challenge posed
by the drilling on Mars during the 2007 mission, within the resource
constraints specified. These has ranged from an innovative solution
which could potentially drill to many hundreds of metres of depth, to
the application of mature terrestrial drilling technologies which can
achieve a few tens of metres of depth, to a very mature space technology
that is applicable to a few metres.

The alternatives analysed are:

DST: This approach is based on traditional technology (it is a drill)
and is targeted to depth up to 1.5\...2 meters using extendible drill
rods. It allows sample acquisitions compatible with various soil
properties and delivery of the samples to scientific in-situ analysis
instrument located at the host platform. Downhole science is also
possible to the extent allowed by envelope for sensors and gauges
available inside the drill tool.

Coiled Tubing Drill (CTD): This alternative utilises a riser/conductor
unit for the penetration into the unconsolidated overburden, of a coiled
tubing drill string for boring the hole, and of a compressed gas lift
system for removing the drill cuttings from the hole during the
drilling. The solution is based on traditional oil field equipment and
therefore the principal innovations shall be the system of compressed
gas to remove drill cuttings, and the automation and control of the
drilling operations. The capabilities shall be to achieve 20 metres
depth with the resources of Cases 1, 2 and 4, while for Case 3 depths up
to 50 metres may be feasible. Sampling shall be provided by the gas lift
system, therefore throughout the depth of the hole, but with a risk of
interlayer contamination. Downhole science is also catered for from
sensors mounted on the drill string, with data being supplied to the
surface through the power and control wire. The main advantage is the
ability to drill through all types of rock, with the removal of drill
cuttings to the surface, while the main risk is associated to the
possible presence of un-consolidated soil to a depth below that reached
by the conductor.

**Hollow-stem Auger Drill (HAD):** This solution utilises a drill string
deployed from a drill frame and made up of a number of flighted tubing
joints that shall permit the removal of drill cuttings. This technology
is currently used down to depths of over 100 metres, although for the
energy resources available depths of 20 metres are considered feasible
based on the conditions of the soil. Innovation shall principally be
tied to the automation of the system, and the development of a power and
rotary system suitable for Martian conditions. Sampling shall be
provided through the bore of the drill string, and shall be performed by
tooling lowered periodically down the bore from a dedicated reel.
Downhole science may also be available on the tool but shall be limited
to logging from inside the drill string. This solution is particularly
adapted to unconsolidated soil and soft rock conditions. Limitations are
given by the power available and the thrust that can be placed on the
bit.

**Worm concept**: This solution utilises high frequency vibrations or
rotary drilling/cutting tools to progress the bit through the soil,
utilising barbs or tracks to put axial pressure on the bit. This is an
innovative technology, although vibrating pile drivers are currently in
use and development of ultrasonic drills is underway. Potentially this
solution could permit drilling to great depths (1000 m) as it does not
require drill cuttings removal or return to the surface. Sampling is not
a feature of the worm, however down hole science can be performed over
the whole depth of the hole due to the hard wire connection to the
surface. The principal risk is tied to the ability of the worm to
progress through incohesive soils.

The table below summarises the main risks and capabilities of the
solutions.

  -------------- ---------------- ------------- --------- -------------- ------------ -------------- -------------------
  **Solution**   **Technology**   **Operative   **Depth   **Sampling**   **Downhole   **Mobility**   **Soil types**
                                  risk**        (m)**                    science**                   

  **DST**        Mature           Very low      2         Yes            Yes          Suitable       All types

  **CTD**        Some innovative  Medium        20 to 50  Yes            Yes          Unsuitable     From soft to hard
                 components                                                                          rock with limited
                                                                                                     depth of
                                                                                                     unconsolidated soil

  **HAD**        Some innovative  High          20        Yes            No           Unsuitable     Loose soil and soft
                 components                                                                          rock

  **Worm**       Very innovative  High          1000      No             Yes          Suitable       All types, but
                                                                                                     without prolonged
                                                                                                     areas of low
                                                                                                     porosity
  -------------- ---------------- ------------- --------- -------------- ------------ -------------- -------------------

In conclusion it can be seen from the above table, that the selection of
the solution shall be tied to the specific depth objectives of the
drilling activity, the risks that are willing to be taken, and the
geologic material of the drill site. Generally the solutions range from
the low risks of the DST that can attain depths of 2 metres, to the
higher risk drilling technologies that can reach a few tens of metres of
depth, to the innovative worm concept that has the potential of reaching
hundreds of metres. The choice between the various types of drilling rig
(CTD and HAD) shall in part be based on the type of soil conditions that
shall be expected at the landing site of the mission, and in part due to
a more in depth analysis of the technological hurdles that must be
overcome.

A combination of two drilling concepts could be considered also, for
instance: DST and Worm drilling stations located at the rover. In such a
configuration DST system ensures reliable sampling in any kind of soil
down to 0.5..0.8 meters (without extension rods) and Worm system can be
activated at most suitable location found after DST samples in-situ
analysis with an attempt to reach depths up to a hundred of meters.
Worst to say that having two drilling systems would increase also a hope
to receive scientific results even in case of failure of one of them.

**APPENDIX F**

**DRILLING WHITE PAPER**

**FROM**

**JPL-BRIAN WILCOX**

Robotic Subsurface Explorer:

Deep Subsurface Drilling with very Low Mass and Power

Brian Wilcox (Supervisor, Robotic Vehicles Group, JPL), PI

**Executive Summary:** It is desired to drill a long distance into
largely unknown terrain. A commercial drilling contractor, if asked to
drill a hole 5 km deep in unknown terrain, would bring in at least 50
tons of equipment and use a prime mover with at least 50 kW of power,
producing a hole averaging perhaps 20 cm in diameter. The volume of this
hole would be about 160 cubic meters and the energy delivered to the
rock face would be about 50 Gj, equivalent to over 17 kW for 100
eight-hour days of drilling. This is vastly more mass and power than can
be landed on Mars in a near-term subsurface exploration mission. This
leads to the natural question \"how much miniaturization of commercial
drilling technology is possible?\"

It is the assertion of this white paper that a drilling system might be
miniaturized to the point where the hole is reduced in linear scale by a
factor of 20 to a diameter of 1 cm or less, reducing the basic energy
requirement by a factor of 20^2^ (or 400) to about 30 Watts or less at
the rock face. Since the volume of the hole is reduced also by a factor
of 400 (still assuming we want to go 5 km) to 0.4 m^3^, and the mass of
all the attendant materials is reduced by a factor between 20^2^ and
20^3^, or somewhere between 400 and 8000. The drilling system can be
composed of a self-contained robotic system downhole, fed by tanks of
consumables pumped from above. If such miniaturization could be
achieved, then the 50 ton, 50 kW system would shrink to of order 100 kg
and 10s of Watts or less and yet still be able to drill 5 km in a
reasonable amount of time. Such a system could revolutionize our
understanding of Mars, since it could explore the cryosphere (the
putative frozen water layer thought to lie a hundred or a few hundred
meters below the surface of Mars at the equator) all the way to the
putative liquid-water hydrosphere at about 5 km depth, one of the few
locales in the solar system which might plausibly harbor exant life.

**Energetics:** The first fundamental parameter about drilling for which
there is abundant field experience and published literature is the
energy requirement. The energy required to penetrate regolith and rock
ranges from 0 to about 300 megajoules per cubic meter of swept volume
for efficient drilling technologies such as percussion, rotary, and
rotary-percussion. Inefficient technologies exist (such as ultrasonic,
laser, water or plasma jets, etc.), but they frequently require 1 to 3
orders of magnitude more energy per unit swept volume than the efficient
methods. Since these other techniques have been extensively studied by
well-funded prior activities from industry and DOE/DOD, the limited NASA
budget probably cannot support any significant efforts in basic research
for novel drilling technologies. Thus we conclude that any NASA drilling
program should concentrate on rotary and/or percussive rock destruction
techniques. Furthermore, it is prudent to assume that the energy
required at the rock face by any deep drilling mission will be the swept
volume of the downhole assembly times 300 Mj/m^3^. This energy
requirement thus scales directly with the cross-section of the hole (for
a given desired depth), and thus is extremely amenable to reduction by
miniaturization of the system components.

How can such component miniaturization be achieved? To answer this
question, we must question the fundamental assumptions which underlie
the current drilling industry, and evaluate each one of them to assess
what the limits to miniaturization are. In most cases, the limits to
miniaturization will either come from basic physics, where the scaling
laws of any approach might become adverse with further shrinkage, or
they will be based on practical limits to how small the needed
components can be built and assembled. These latter limits needs to be
examined very carefully, since the main reason the commercial
exploration well-drilling industry uses equipment of the scale that they
do is because of tradition, rules-of-thumb, perceived user requirements,
and perhaps prejudice that things need to be built at some particular
scale which happens to be convenient for manufacturing and handling in
the field.

**Scaling:** As mentioned above, it is not uncommon for the current
drilling industry to drill holes which are thousands of times longer
than their diameter. This suggests that there is no fundamental physical
reason that this ratio is limited, since aspect ratios which are limited
by physical law or fundamental material properties are generally in the
range of 10s to at most 100s. In this case, the hole liner or drill pipe
is supported by the terrain material over its length, and so there is no
fundamental physical reason why any particular "downhole assembly" (e.g.
some sort of drill), given a supply of power and a volume to put the
cuttings, cannot continue to drill indefinitely through the subsurface
environment (or at least until pressure or temperature extremes at very
great depth become a factor). There is no fundamental limit to
miniaturizing such downhole assemblies until the atomic dimensions
become significant for key subassemblies. We might expect that our
ability to manufacture and assemble robust downhole assemblies at small
scales would be the limitation. If we wish to make holes only 1 cm in
diameter (which, although small, is still about 40 million atoms across)
and yet kilometers long, then we wish to create holes with aspect ratios
of 10^5^:1 or more, up from today\'s values which approach 10^4^:1.
There appears to be no fundamental physical reason why this should be
impossible or even difficult. (There is also the important issue of
steering, to be addressed later.)

One key fact we must recognize is that any deep drilling system must
maintain an open hole to the surface. Since comminution (destruction) of
non-porous rock creates particles which occupy a volume some 40% larger
than the original rock, it is vitally important to be able to convey the
excess volume to the surface. While these particles can generally be
compressed to about 110% of their original volume, getting below 105% is
prohibitively difficult in terms of pressure and energy, since to do so
would require that the particles be subjected to such high pressure that
the solid rock flows like a fluid. Thus at least 5-10% of the swept
volume of the downhole assembly, plus the volume of the open hole and
any liner, must be extracted to the surface. The fact that there must be
an open hole and a means for conveyance implies that scientific samples
can also be brought to the surface from depth, thereby allowing the
system designer to perform only those measurements in-situ which
absolutely must be done down the hole. This reduced requirement for
down-hole science may greatly reduce the needed swept volume of the
down-hole assembly to a few key sensors (temperature, etc.) and a
sampling device.

How big does the open hole need to be? An implicit assumption of the
conventional drilling industry is the concept of \"tripping the bit\"
(i.e. withdrawing the down-hole assembly back to the surface for
maintenance, repair, or replacement). For our purposes, it is much more
prudent to devise a long-life downhole assembly, which does not need to
be withdrawn to the surface. At the Spokane Mars Drilling workshop
hosted by NASA Ames Research Center (13-15 Sep 2000), there was
widespread agreement from the drilling community that a single, general
purpose rotary diamond bit would be adequate for almost any type of rock
that might be encountered. On Earth bits are mostly tripped because they
break, wear out, or the rate of penetration falls below commercial
expectation. But this concept relies on the fact that there is a highly
dexterous and relatively inexpensive system at the top (the human) that
can perform the necessary manipulation. However, for our application
there is no human at the surface to perform such maintenance or repair,
and it would be very expensive (in cost as well as mass and power) to
have some robotic system at the surface for these functions.
Conventional diamond faceted drill bits are able to wear down
approximately 1/10th of their diameter before they are worn out. Diamond
drill bits normally wear at a rate of 1/25,000 the rate at which they
cut hard rock. Thus we find the first real aspect-ratio problem for
drilling: a conventional bit can only drill perhaps 2500 times it's own
diameter before it is worn out. For a 10-cm conventional drill, this is
about 250 meters. For a 1-cm drill, it would be 25 meters. This seems to
be a serious limitation.

Our team includes the premier manufacturer of custom drill bits for
subsurface drilling, Christensen Products of Salt Lake City, UT. Our
team has designed and built a proprietary custom 1 cm diameter diamond
drill bit which is now under test which can wear 10 times its own
diameter before it is worn out. Thus this drill is expected to be able
to cut up to 2500 meters in solid basalt without replacement. If
successful, we believe that it can be extended to produce a bit which
can wear many 10s of diameters before being worn out. At the observed
wear rates of diamond bits, this would mean that a 20-cm long bit would
be able to drill 5000 meters without replacement.

Once we eliminate the need to have a large bit just to increase the wear
life, then the size of the open hole is defined by the cuttings removal
problem, the power supply problem, and the mass of material we are
willing to allocate to lining the hole.

**Hole Stability:** The open hole must be supported with some kind of
liner for at least some part of its length. Since it is known that the
volume of all the impact craters observed on Mars would cover the entire
surface of Mars to a depth of a few km, one cannot rule out the
possibility that mixtures of rock and loose or semi-compact regolith
will be encountered at almost any depth. Thus hole stability is an issue
for any open hole, even if the troublesome pockets of pressurized fluids
found on Earth are not encountered. Thus it is prudent to assume that
the hole must be lined for its entire length. Once we adopt this
conservative design approach, we accrue the advantage that any
"shuttles" we may wish to include in the system design, which move back
and forth between the downhole assembly and the surface for science
sampling, downhole instruments, cuttings removal, or any other purpose,
have a completely defined and enclosed environment in which to operate.

This PI has developed (and a patent has been filed on) a \"cast in
place\" hole liner, formed from a two part mix similar in concept to 5
minute epoxy. The two fluid parts would pass to the downhole assembly
through passages cast in the liner, they would be mixed at the bottom,
and the liner would be extruded at the bottom as the drill assembly
moves down. This approach has the advantage that it will permit science
samples taken by a sidewall sampling shuttle sent down the open hole to
be raised to the surface. These samples could have a smallest dimension
of 7 or 8 mm, if that is the size of the open hole. It would seem that
such samples are adequate for a first set of exploratory missions, since
so long as the sample is large compared to the grain size of the
minerals, most of the science value is retained. While large, even meter
scale crystals might exist anywhere; most rock samples on Earth have
grain sizes of order 0.1 mm.

![](media/image53.pct)

**Reacting forces on the bit:** A significant issue facing the system
designer is how to react to the force and torque applied to the drill
bit. An industry rule of thumb is that a diamond bit requires a thrust
force (Weight on Bit, or WOB) of about 8.3 MPa (1200 PSI) averaged
across the cutting face, which for a 1 cm diameter bit is about 650 N
force, and if we wish to expend a continuous mechanical power of up to
30 watts at 2000 RPM, the reaction torque would be 0.14 N\*m. Let us
examine the possibility that these forces and torques can be reacted
against the cast in place liner. We would expect, based on resistance to
buckling, that the cast in place liner needs to have an ID of perhaps
80% of the cutter OD. To maintain a frontal pressure of 8.3 MPa, the
working stress in the liner material would then need to be about 22 MPa
(3300 PSI), which is not unreasonable. It may not be necessary to use
quite such high frontal pressures as the industry norm and yet get good
cutting performance and low specific energy. This would further reduce
the liner stress and greatly expand the range of possible materials used
for the liner. An experimental program to evaluate this possibility is
underway.

**Cuttings Removal:** How can we remove the cuttings from the drill bit?
On Earth chips are removed from deep drilling systems with the use of
fluids such as mud, water, foam, or compressed air. For drilling using
liquids, it is common for commercial drill rigs to use a total volume of
fluid of about 50 times the volume of the finished hole. Since the
density of any liquid is going to be comparable to the density of the
liner material, this means that the total mass of liquid might be dozens
of times that of the liner material. Clearly this is unacceptable if our
overall mass targets are to be achieved.

Instead, let us examine cuttings removal using a gas. A drilling
industry rule of thumb is that pneumatic chip removal is highly
effective so long as the flow velocity of the returning air stream is at
least 3000 ft/min (15 m/s). At normal atmospheric density, this
corresponds to a mass flow density of about 20 (kg/s)/m^2^. As a sanity
check, this mass flow rate would allow levitation of spherical particles
of density 2500 kg/m^3^ with a diameter as large as 9.3 mm in Earth
gravity. We believe that there is a way to flush the cuttings adequately
with a mass flow rate of fluid comparable to the mass flow rate of
cuttings generation or the mass flow rate of liner extrusion at the
bottom of the hole. This means that the total consumables mass of the
system will, once again, scale with the cross-sectional area of the
hole.

**Steering:** It is important for the subsurface explorer to be able to
steer. Vertical sensors in the downhole assembly will detect any
variance from a vertical hole. Just behind the drill motor assembly
would be located one or more "steering knuckles". Each steering knuckle
would be a high-torque rotary actuator which could force a "kink" in the
downhole assembly. This would force the drill bit against the side of
the hole (in addition to whatever axial force it may have), so that the
drill will preferentially cut in some desired direction. Behind the
steering knuckles, it may be prudent to have a long telescoping section
which can isolate and maintain the desired force on the bit, but allow
the cutter to withdraw a meter or more if some steering action is needed
to go around some obstacle. This telescoping section can be filled with
pressurized cutting fluid to shock-isolate the active cutting section
from the rear.

**Overall System Description:** Thus we can now form a description of a
deep drilling system which operates with low mass and low power and yet
creates an open hole hundreds or thousands of meters long through
natural terrain. This system consists of a downhole assembly
incorporating a long-life rotary or rotary/percussive drill bit roughly
1 cm in diameter or less, designed to have a useful cutting life of
hundreds or thousands of meters of rock. It seems that to adequately
miniaturize the drill mechanism, it will be hydraulically actuated.
There will be steering actuators behind the drill motor to allow the bit
to be forced against the side of the hole if desired, reacting against
the length of the downhole assembly pushing against the side of the
hole. There will be a telescoping section, which allows the drill bit to
be withdrawn if necessary to allow the system to steer around obstacles
it may have encountered. The downhole assembly will have vertical
sensors to determine its inclination. The downhole assembly will have
means for changing the magnitude and direction of the force on the bit,
the torque applied to the bit, and the rate of flow of cutting removal
gas. At the rear of the downhole assembly will be a mechanism for
casting the hole liner behind it. The majority of the cross-section of
the hole will be left open, but the liner will have enough integrity to
support the static forces and torques applied to the bit. The liner will
have auxiliary channels of various cross-sections cast into it for
purposes such as carrying the cutting fluid, returning the cuttings to
the surface, carrying electrical wires, etc. The liner will be extrusion
cast from a 2 (or multi) part medium whose component parts can be
readily transported to the bottom for use, and whose strength is
adequate to react to the needed forces and torques, as well as to resist
the needed pressures of the cutting fluid and the overburden pressure.
All of these pressures are of comparable magnitude. At the surface would
be an electric pump to pressurize the fluids used in the system.
Finally, there would be a deployment device, which is a tube that holds
and squeezes the downhole assembly and presses it against the terrain
while the extrusion of the initial segment of the cast-in-place liner
(inside the deployment device). The cuttings may be caught in some sort
of collector at the top as they are blown out of the hole, if desired,
for purposes such as scientific analysis.

Shown below is a table of the key characteristics of this device. Using
conservative assumptions regarding the likely efficiencies, material
properties, etc., this shows that a single, identical system can be used
to drill holes ranging from 300 meters to 5000 meters. (The only system
differences are sizes of tanks for consumables, etc.) Sized to use
between 20 and 30 Watts of bus power, the system can drill 500 meters in
86 8-hour days (190 W-hrs/day) using 39 kg of cutting fluid and 19 kg of
liner material, with a total system mass of 73 kg (not including
sampling, but the simplest sampling approach, to catch the cuttings as
they fly out of the hole, would presumably have very low mass).

This same system could be used to drill a 5000 meter hole if the mass
allocation and mission duration permitted. Using all the same system
components (same downhole assembly and same surface pump and plumbing
arrangement, just bigger tanks) the system could drill 5000 meters in
282 sols (continuous Mars days, or 725 W-hrs/day) using 386 kg of
cutting fluid and 189 kg of liner material.

![](media/image9.pct){width="5.135416666666667in"
height="3.1465277777777776in"}

Note that this approach eliminates the conventional surface rig and
drill tower, since nothing needs to be inserted or retracted up the hole
after the hole is begun except spooled or fluid materials. The only
surface equipment required is a hydraulic pump, tanks of fluid, spool of
wire, and the deployment device, which provides the needed \~500 N of
weight (131 kg of mass in Mars Gravity) to launch the subsurface
explorer. Once the cast liner is many diameters deep in the terrain, all
the reaction forces will be transmitted from the liner to the
surrounding terrain.

It is a fair question to ask, "How important is the Mars Environment, as
compared to the Earth environment, for drilling?" It is the assertion of
this white paper that, compared to the issue of needing to miniaturize
the drilling equipment by a factor of 1000 in mass and power, that the
issues relating to the different thermal and pressure environment on
Mars are relatively minor. There is widespread agreement in the
planetary science community that the same sorts of rocks will be
encountered on Mars as on Earth. For equatorial Mars, the diurnal
average temperature is above --60C at the surface, and that temperature
is expected to rise to about 0C at 5-km depth. Drilling basalt on Earth
will be basically the same as drilling basalt on Mars, with the possible
exception that the rock will likely be somewhat more brittle at low
temperature and thus more amenable to fracture. However, there is
abundant experience drilling in the Polar Regions on Earth (one of our
team, Prof. Eustes of the Colorado School of Mines, regularly consults
on drill rigs on the North Slope of Alaska). It seems likely that the
pressure difference of 5 mbar vs. 1 bar will likely be no issue at all,
since the cutting fluid needed to remove the cuttings will almost
certainly be at significant pressure, much higher than Mars ambient, to
drive the chips out of the hole. It is certainly worth doing some
experiments to validate that the comminution processes of rotary and
percussion drilling don\'t suffer with the reduction in pressure, and of
course all the materials used in the drilling system must have suitable
propertied over the expected range of Mars temperatures. There appears
to be no physical phenomena, which would seriously affect the rock
fracture process under the pressures and relatively modest 20% change in
Kelvin temperature associated with Mars.

**Conclusions and recommendations:** There appears to be no fundamental
reason why the diameter of a deep drill cannot be made much smaller than
the current commercial practice. Such miniaturization will generally
reduce the energy and fluid requirements by a factor at least
proportional to the change in cross-section, for a fixed target depth.
The overall design concept advocated here is 1) that the system mass and
power will be roughly proportional to the square of the hole diameter
and 2) that we thus need to make a long-life bit with a small

diameter. The issues of if or how we line the hole, how power is
delivered, etc. are important but secondary.

It is appropriate to develop the technology in the order needed to test
it: first the bit (which can initially be spun on a long tube, now
ongoing), then the cutting removal technique (e.g. a long narrow tube
running up the support tube having the appropriate gas flow velocities),
then the downhole motor (which can be supported on a non-rotating tube),
and lastly the hole liner or method of reacting to the needed forces and
torques (to complete the test setup). It would be very difficult to
perform any useful tests if the subsystems are not developed in about
this order. In the technology prioritization subgroup at the NASA
Subsurface Access Workshop (LPI, Houston, 27-28 February 2001), bit
design came out as 2nd priority in the short term (20 m), 1st priority
in the mid term (200 m), and 2nd priority in the long term (5000 m).
Chip transport was identified as 1st priority in the short term and 3rd
in the long term, which is a fairly good match to the proposed
development approach. Overall system miniaturization, which is the theme
of this concept and key to downhole motor and stuck-bit mechanism
development, came out 4th priority in the short term and 2nd priority in
the mid term, which is fairly well aligned with the approach given here.
Hole lining was 3rd priority in both the short and mid term and would be
developed next under the concept. Thus the consensus view of the
industry experts at the workshop are in good agreement with the proposed
development strategy advocated here.

After the long-life bit, chip removal technique, and down-hole motor are
developed and demonstrated, we may use the cast-in-place liner to react
the forces and torques from the downhole assembly against this liner,
thereby avoiding reliance on the terrain properties to provide the
reaction. However, it is also possible that it will be concluded that
the terrain properties will be such that the hole does not need a
continuous liner, or that we can slide a liner tube down from the
surface as in conventional drilling, or take some other approach to hole
lining. The fundamental concept is not tied to the cast-in-place hole
liner, but rather that extruding a hole lining from the bottom is one of
many ways to address that secondary issue. What is most important is to
reduce the mass of the conventional approach by 2-3 orders of magnitude
via miniaturization of the hole diameter by a factor of 20 from the
conventional industry practice. It seems that there is a clear NASA
benefit to such miniaturization, given the launch cost penalty for mass.
By limiting the hole diameter to only 1 cm, we can afford to send to
Mars enough materials to fill the entire hole volume with structure,
plumbing, and fluids as needed. What is proposed here is an attempt to
do so simply and reliably.

Even using a relatively conservative average specific energy of about
300 MJ/m^3^ for a rotary diamond bit to cut the terrain, the energy and
power requirements for attractive NASA missions of subsurface
exploration on Mars appear acceptable. So also do the requirements for
fluid to flush the chips and to line the hole. The chips are flushed out
of the hole and can form the basic scientific sample. An open hole
approximately 7 mm in diameter is provided for further sampling or
in-situ science instruments. Within 100 kilograms and 200 W\*hrs/day, it
seems possible to make a system which can drill 300-500 meters deep.
With somewhat more mass, the identical system components can be
configured to drill 3-5 km or more to search for the liquid water
aquifer and possible extant life.

**APPENDIX G**

**DRILLING WHITE PAPER**

**FROM**

**UTD/JPL**

The Low Reaction Force Drill -- A Recommendation For Drilling On Mars

> By John Hill^\*^, Ben Dolgin^\*\*^, Joram Shenhar^\*^, Brian
> Turner^\*^, Mark Lombardo\*, and Steve Solga\*
>
> ^\*^UTD Incorporated, 10242 Battleview Parkway, Manassas, VA
> 20109-2336
>
> ^\*\*^JPL, California Institute of Technology, M/S 82-105, 4800 Oak
> Grove Drive Pasadena, CA 91109-8099

**SUMMARY**

The Low Reaction Force Drill (LRFD) is a new drilling system concept
that offers a low-energy, low mass, self-advancing solution for drilling
on Mars or other planetary bodies. The distinct advantages of the LRFD
are its ability: to provide down-hole, self-contained torque by
counteracting multiple concentric drill bits; to provide axial weight on
bit by bracing against rock or regolith that has not been fully drilled
through; and to produce cuttings particle size that is orders of
magnitude larger than conventional drill cuttings thereby reducing
excavation energy requirements. The system has application for shallow
drilling (2 to 200 meters) through kilometer class drilling in a broad
range of materials, and allows for down-hole, real-time instrumentation,
and the selective retrieval of samples. The LRFD is a departure from
conventional drilling technology in mode of excavation and thus in power
consumption and advance technique. Limited component and prototype
testing to date confirms system feasibility (Hill, 2000; Kiroshoni,
1998; Amini, 1998).

This white paper describes an analysis of the LRFD that derives
performance predictions for three mars drilling applications. The
predictions are summarized in Table 1. Substantial energy and mass
margins were held in reserve when deriving predictions.

**BACKGROUND**

Conventional drills work by applying pressure and rotating a bit against
the rock. Weight on bit and torque delivery systems are the major
drawbacks of conventional drills with regard to drilling on Mars. On
Earth, these problems are typically solved by large drill rigs located
on the surface (large mass), large surface motors with large fuel
supplies, and rigid drill pipe for transmitting torque and weight on bit
from the surface to the bit. Down-hole motors are sometimes used to
eliminate the problem of transmitting torque along the length of the
drill pipe, but these systems consume even larger quantities of energy
since that energy is transmitted by pumping fluid into the drill pipe at
high rates. In general, conventional Earth drilling techniques are hard
to implement on Mars because of low gravity (reduced weight on bit),
difficulties in transporting large quantities of high mass drill pipe to
Mars that is capable of transmitting torque and weight on bit, very
limited energy supply, and difficulty in removing cuttings and
stabilizing holes in unconsolidated materials while retaining the
capability to drill through hard consolidated material. These problems
are solved by the application of the LRFD.

The main advantages of the LRFD are its ability to break the surface and
perform a transition from soil (sand or regolith) to rock without the
necessity of applying significant force from the surface structure or
requiring that reaction forces be transmitted through the hole casing.
As a result, hole casing only needs to be rigid enough to maintain hole
stability (as opposed to also being able to transmit axial force for
weight on bit and torque). Lack of weight on bit requirements during
breaking the surface permits lighter drilling platforms (mass savings).
The large size of the chips produced by the LRFD as opposed to the
powder produced by conventional drills, reduces specific energy of
drilling. Energy required per meter of the drilled well decreases in
proportion to the specific energy (energy savings). In addition, large
size of chips permits sophisticated mineralogical analysis without
requirement to produce cores. Core production can complicate drilling
since it requires additional operations such as core breaking and core
retention. The LRFD can deliver large intact rock samples ( \> 1 cm^3^ )
from a depth defined as accurately as 5 cm.

![](media/image54.png){width="0.9771653543307086in"
height="2.148425196850394in"}![](media/image55.png){width="0.8771653543307086in"
height="3.558267716535433in"}![](media/image56.png){width="0.9216535433070866in"
height="3.5484251968503937in"}![](media/image57.png){width="1.1216535433070867in"
height="3.501574803149606in"}![](media/image58.png){width="1.0216535433070866in"
height="3.5354330708661417in"}**Details of Operation:** As shown in
Figure 1, comminution of the rock or soil is performed by several
components that work in series. The individual action of each component
relies on the reaction force capability of the numerous other stationary
components and allows the system to self-advance, step-by-step through a
broad range of materials. The individual component action also reduces
instantaneous power requirements. The first step involves advancing a
pilot bit into the rock or regolith relying only on the weight of the
drilling system and minimal rotational reaction force. A sheath covers
the auger blade pilot shaft to convey pilot cuttings to a bailing bucket
above the drill bit system. Once extended to maximum reach (about 0.3 m,
or less if working in highly fractured rock, rubble or sand) the pilot
bit rotates in place to allow the helical auger (inside a sheath) along
its shaft to transfer cuttings away from the pilot hole area. The sheath
then retracts to engage the first helical flight. The first helical
flight is then rotated and thrust forward in a prescribed ratio by the
sheath. The flight creates a spiral groove (or thread) in the pilot hole
walls. The drive tube (sheath) is retracted from the first flight to
engage the second helical flight and in consecutive steps the remaining
helical flights are individually advanced to the bottom, consecutively
deepening the groove in the rock. Finally, a thread breaker flight is
advanced that breaks off the rock ridges. For a final hole diameter of
about 80 mm (practical range of finished hole diameter is 50 mm to 250
mm) the chips formed by thread breaking are 2 to 3 cm in length and are
captured in a bailing bucket along with pilot cuttings from the pilot
auger shaft. As the bailing bucket is filled, it is then sealed at the
bottom by rotation of an internal auger to close a window in the bottom
of the bucket. It is then lifted to the surface by a winch wire-line
system.

The bending action of the thread breaker, breaks the ridges in tension
forming large chips (Figure 2). A large portion of the volume of the
hole is thus excavated through the tension failure mode (the weakest
rock strength mode) creating large chips requiring less power
consumption per rate of advance than grinding or pulverizing techniques.
The rock threads also provide a source of down-hole reaction force for
generating torque and weight-on-bit, circumventing the need for reaction
force from the surface during down-hole drilling and requiring very
little reaction force during drilling initiation on the surface.
Ultimately the LRFD creates a larger hole per energy used than other
techniques and creates rock chips of a size that is useful for
scientific analysis. (The helical cutter flights expand the hole from
the pilot hole diameter to a finished hole diameter ( 82 mm) at a power
consumption rate of about 120 MJ/m^3^ for medium strength rock. Typical
rotary drilling systems require more than 200 MJ/m^3^ (Maurer, 1969), as
does the pilot hole excavation.)

**Mixed Media Drilling:** The system is able to advance through a broad
range of materials including sand to cobble size rubble, to fractured
rock, to massive hard rock. Additionally, transitioning from one medium
to the other is simply a matter of technique, not a matter of adding
other hardware. In the case of dry sand, the independent action of the
pilot bit thrusting into the material, followed by independent advance
of each flight allows for step-by step advance of the whole system. As
rubble or fractured rocks are encountered the pilot bit may advance in
unison with one or several helical flights to increase pilot shaft
stability to improve down-hole equipment durability and advance rate.
Slip casing can be placed directly behind the thread breaker (around the
outside of the bailing bucket) to ensure hole stability. The mass of the
down-hole system and independent action of drilling components allows
the system to provide sufficient reaction force when drilling from
within sand to rock. Since the LRFD does not rely on the casing for any
reaction force and does not require additional bracing to advance, the
casing material can be made of lighter weight material that only needs
to resist hole collapse (typically much less stress than providing
conventional drilling reaction forces). Additionally, the casing can be
deployed only in regions where it is required rather than the whole
length of the hole.

**The Full LRFD Down-Hole System:** As shown in Figure 3, the LRFD
utilizes a down-hole electric motor and a planetary gear system to
provide variable rotation to independent components (separate rotation
and thrust for pilot bit versus helical flights). Depending on the depth
of hole, a down-hole battery is used (holes greater in depth than about
300 m) or by direct wire-line to the surface for shallower holes. Solar
power is sufficient for many applications to charge the down-hole
battery. Cuttings are removed to the surface in a bailing bucket by a
surface winch. The system is monitored and controlled through down-hole
and surface electronics. When casing is needed it can be dispensed in
segments and delivered in a smaller diameter mode by the bailing bucket
to the horizon requiring stabilization. Once at the area requiring
stabilization a ring around the bailing bucket is pulled upward by the
surface winch as the LRFD advances. The final hole diameter is slightly
smaller than the other parts of the hole but still large enough to allow
for the free passage of the bailing bucket and other components.

![](media/image61.png){width="4.156299212598425in"
height="2.6826771653543307in"}**PERFORMANCE PREDICTIONS**

As a means of comparing the predicted performance of the LRFD with other
technologies, the three cases described in Table 1 were considered. The
mass of the LRFD equipment required to accomplish drilling is broken
down by component in Table 2. Mass was specifically reserved for
shipping requirements and for potential addition of future mission
requirements. In general the LRFD can be configured to accomplish most
drilling objectives within a 100 kg budget. Larger mass budgets do
improve drilling performance when more power is available because they
allow for larger down-hole batteries that increase the drilling time
between return trips to the surface to bail the hole and to switch or
recharge the battery. Tripping the bailing bucket becomes a significant
drain on power resources after about 2 km. Case 1 of Table 1 is divided
into three separate cases in Table 2 to allow for LRFD configuration
changes for predictive purposes. The increase in mass for cases 2 and 3
is related to heavier battery requirements and the dramatic increase in
the amount of wire required for bailing the hole.

+-------------------+-----+------+----+-------------------------------+
| ## Ta             |     |      |    |                               |
| ble 2. The LRFD M |     |      |    |                               |
| ass Budget Provid |     |      |    |                               |
| es Margins For Fu |     |      |    |                               |
| ture Requirements |     |      |    |                               |
+-------------------+-----+------+----+-------------------------------+
| **Item**          | *   | **M  | *  | **Note**                      |
|                   | *Ma | ass, | *M |                               |
|                   | ss, | kg   | as |                               |
|                   | kg  | C    | s, |                               |
|                   | Ca  | ases | kg |                               |
|                   | ses | 2    | Ca |                               |
|                   | 1a- | -3** | se |                               |
|                   | c** |      | 4  |                               |
|                   |     |      | ** |                               |
+-------------------+-----+------+----+-------------------------------+
| **MARGIN -**      | **1 | *    | *  | **Gross estimate (Not as many |
|                   | 0** | *6** | *6 | heaters needed for cases      |
| **Electronics,    |     |      | ** | 2-3)**                        |
| heaters,          |     |      |    |                               |
| cabling**         |     |      |    |                               |
+-------------------+-----+------+----+-------------------------------+
| **MARGIN - Launch | **1 | **   | *  | **Gross estimate**            |
| restraints, pyro  | 0** | 10** | *6 |                               |
| releases,         |     |      | ** |                               |
| protective        |     |      |    |                               |
| coverings**       |     |      |    |                               |
+-------------------+-----+------+----+-------------------------------+
| **MARGIN - for    | **3 | **   | *  | **Gross estimate**            |
| future            | 0** | 30** | *6 |                               |
| modifica          |     |      | ** |                               |
| tions/additions** |     |      |    |                               |
+-------------------+-----+------+----+-------------------------------+
| **Bit assembly    | **  | *    | *  | **Reduction from earlier      |
| (Pilot and HDB    | 3** | *3** | *3 | estimates. These values are   |
| flights and       |     |      | ** | based on an actual            |
| initializer)**    |     |      |    | prototype.**                  |
+-------------------+-----+------+----+-------------------------------+
| **Planetary gear  | **  | *    | *  | **Based on mfr estimate and   |
| assembly and      | 4** | *4** | *3 | similar systems.**            |
| housing**         |     |      | ** |                               |
+-------------------+-----+------+----+-------------------------------+
| **Brushless motor | **  | *    | *  | **Based on mfr estimate and   |
| and housing**     | 4** | *4** | *3 | similar systems.**            |
|                   |     |      | ** |                               |
+-------------------+-----+------+----+-------------------------------+
| **Down-hole       | **  | *    | *  | **Based on vendor data.       |
| battery**         | 0** | *8** | *0 | (Cases 1a-c) use hardwire     |
|                   |     |      | ** | power supply from surface)**  |
+-------------------+-----+------+----+-------------------------------+
| **Cuttings        | **  | *    | *  | **Based on design             |
| carrier**         | 2** | *2** | *2 | specifications.**             |
|                   |     |      | ** |                               |
+-------------------+-----+------+----+-------------------------------+
| **Steel cable**   | **  | *    | *  | **Based on off-the-shelf wire |
|                   | 1** | *4** | *1 | specifications that will meet |
|                   |     |      | ** | performance requirements.**   |
+-------------------+-----+------+----+-------------------------------+
| **Top side        | **  | *    | *  | **Based on similar systems.** |
| winch**           | 5** | *5** | *4 |                               |
|                   |     |      | ** |                               |
+-------------------+-----+------+----+-------------------------------+
| **Casing (liner   | **  | *    | *  | **Liner is relatively         |
| for top 10 m of   | 5** | *5** | *4 | flexible and is transported   |
| hole)**           |     |      | ** | flat and rolled, then molded  |
|                   |     |      |    | at site.**                    |
+-------------------+-----+------+----+-------------------------------+
| **Second          | **  | *    | *  | **Left on surface for         |
| down-hole battery | 8** | *8** | *4 | charging when other down-hole |
| or surface        |     |      | ** | battery is in use.**          |
| battery**         |     |      |    |                               |
+-------------------+-----+------+----+-------------------------------+
| **Mechanism for   | **  | *    | *  | **Liner to be installed for   |
| liner insertion** | 4** | *4** | *3 | first 10 meters of            |
|                   |     |      | ** | drilling.**                   |
+-------------------+-----+------+----+-------------------------------+
| **Control         | **  | *    | *  | **CPU, memory, control chips, |
| electronics**     | 2** | *2** | *2 | comm. interface.**            |
|                   |     |      | ** |                               |
+-------------------+-----+------+----+-------------------------------+
| **Down-hole       | **  | *    | *  | **Includes sapphire window,   |
| Science           | 5** | *5** | *3 | down-hole canister, cabling,  |
| Instruments**     |     |      | ** | sensors**                     |
+-------------------+-----+------+----+-------------------------------+
| ** TOTAL**        | **9 | **1  | ** | **Further weight savings      |
|                   | 3** | 00** | 50 | possible by using titanium    |
|                   |     |      | ** | (estimate 10 to 20 kg savings |
|                   |     |      |    | in cases 1-3).**              |
+-------------------+-----+------+----+-------------------------------+

+----------------------------+------+------+------+------+------+-----+
| **Table 3. LRFD Power      |      |      |      |      |      |     |
| Availability Per Case.**   |      |      |      |      |      |     |
+----------------------------+------+------+------+------+------+-----+
|                            | **   | **   | **   | **   | **   | **C |
|                            | Case | Case | Case | Case | Case | ase |
|                            | 1a** | 1b** | 1c** | 2**  | 3**  | 4** |
+----------------------------+------+------+------+------+------+-----+
| Days of activity           | 120  | 120  | 120  | 1095 | 1095 | 180 |
+----------------------------+------+------+------+------+------+-----+
| Day time available power   | 200  | 200  | 200  | 220  | 600  | 200 |
|                            |      |      |      |      |      |     |
| Watt-hrs per sol           |      |      |      |      |      |     |
+----------------------------+------+------+------+------+------+-----+
| Night time available power | 75   | 75   | 75   | 220  | 600  | 75  |
|                            |      |      |      |      |      |     |
| Watt-hrs per sol           |      |      |      |      |      |     |
+----------------------------+------+------+------+------+------+-----+
| Total available power      | 275  | 275  | 275  | 440  | 1200 | 275 |
| (Battery storage assumed   |      |      |      |      |      |     |
| and accounted for in mass  |      |      |      |      |      |     |
| calculations.) Watt-hrs    |      |      |      |      |      |     |
| per sol                    |      |      |      |      |      |     |
+----------------------------+------+------+------+------+------+-----+
| **MARGIN** Nighttime power | 75   | 75   | 50   | 50   | 200  | 75  |
| devoted to other. Watt-hrs |      |      |      |      |      |     |
+----------------------------+------+------+------+------+------+-----+
| **MARGIN** Day time power  | 100  | 50   | 25   | 40   | 200  | 25  |
| devoted to other Watt-hrs  |      |      |      |      |      |     |
+----------------------------+------+------+------+------+------+-----+
| Total available battery    | 100  | 150  | 200  | 350  | 800  | 200 |
| power for drilling,        |      |      |      |      |      |     |
| control, lining and        |      |      |      |      |      |     |
| bailing, Watt-hrs per sol  |      |      |      |      |      |     |
+----------------------------+------+------+------+------+------+-----+

Table 3 lists the power assumptions that were made before predictions of
drilling system performance were made. Significant amounts of available
power have been reserved for heaters and control functions. In cases 2
and 3 the margins reserved are likely more than is necessary meaning
that performance predictions are conservative and/or this additional
power would be available for additional lining or other activities at
depth if needed.

The drilling system must spend a certain amount of power on drilling
support activities such as lining the hole near surface, bailing the
hole, computer controls, and monitoring. Table 4 lists the power
consumption for these activities in terms of their impact on the "days"
available for drilling. Power is expressed in terms of "days" by
dividing the total Watt-hrs required for the activity by the total
available battery power per sol identified in Table 3.

  -------------------------- -------- -------- ----------- -------- -------- --------
  **Table 4. Drilling                                                        
  Support Activities Further                                                 
  Reduce Available Power For                                                 
  Drilling.**                                                                

  ** **                      **Case   **Case   **Case 1c** **Case   **Case   **Case
                             1a**     1b**                 2**      3**      4**

  Days of activity           120      120      120         1095     1095     180

  Bailing power consumption  0.5      1.8      2.7         149.3    433.0    4
  (Total days impact)                                                        

  Liner insertion (200       2.0      1.3      1.0         0.6      0.2      1.0
  Watt-hr total) (Total days                                                 
  impact)\*                                                                  

  Controller (6              7.2      4.8      3.6         18.8     6.6      3.6
  Watt-hrs/day) 2 hours use                                                  
  per day (Total days                                                        
  impact)                                                                    

  Resulting impact on        9.7      8.0      7.4         168.7    439.8    7.2
  drilling time (days)                                                       

  Days available for         110.3    112.0    \*\*120.0   926.3    655.2    184.2
  drilling (assumes power                                                    
  availability per day as                                                    
  shown in Table 2.)                                                         
  -------------------------- -------- -------- ----------- -------- -------- --------

> \* Liner insertion power assumes that only first 10 meters of the
> borehole are lined.
>
> \*\* Case 1c days are intentionally left at 120 implying all power is
> available for drilling.

While the LRFD is expected to be able to excavate through sand to rubble
to soft rock and hard rock, it is difficult to assess the power
consumption expected for drilling through sand and rubble. Testing will
be necessary in these media but preliminary lab indications suggest that
both cases will require less power per meter of advance than that
required for drilling through hard rock. Table 5 lists the power
consumption requirements for the actual drilling action for the pilot
bit and the helical drag bit cutters in both soft rock and hard rock.

+-----------------------+------------+-----------+--------------------+
| **Table 5. Drilling   |            |           |                    |
| Power Consumption Per |            |           |                    |
| Meter Advance (work)  |            |           |                    |
| in**                  |            |           |                    |
|                       |            |           |                    |
| **Hard Versus Soft    |            |           |                    |
| Rock. (Accounts for   |            |           |                    |
| motor efficiency of   |            |           |                    |
| 65%)**                |            |           |                    |
+-----------------------+------------+-----------+--------------------+
|                       | Hard Rock  | Soft Rock | Power values to    |
|                       |            | (σ~u~= 50 | left used in       |
|                       | (σ~u~= 200 | MPa)      | performance        |
|                       | MPa)       |           | predictions for    |
|                       |            | Watt-hr/m | cases              |
|                       | Watt-hr/m  |           |                    |
+-----------------------+------------+-----------+--------------------+
| Pilot bit (20 mm)     | 46         | 11.5      | 1b, 1c, 2, 4       |
+-----------------------+------------+-----------+--------------------+
| Pilot Bit (30 mm)     | 103        | 26        | 1a, 3              |
+-----------------------+------------+-----------+--------------------+
| Helical Drag Bit      | 75         | 19        | 1c, 4              |
| (20-51 mm)            |            |           |                    |
+-----------------------+------------+-----------+--------------------+
| Helical Drag Bit      | 202        | 50        | 1b, 2              |
| (20-80 mm)            |            |           |                    |
+-----------------------+------------+-----------+--------------------+
| Helical Drag Bit      | 181        | 45        | 1a, 3              |
| (30-80 mm)            |            |           |                    |
+-----------------------+------------+-----------+--------------------+
| Total Hole 20mm-51mm  | 121        | 30.5      | 1c, 4              |
+-----------------------+------------+-----------+--------------------+
| Total Hole 20mm-80mm  | 248        | 61.5      | 1b, 2              |
+-----------------------+------------+-----------+--------------------+
| Total Hole 30mm-80mm  | 284        | 71        | 1a, 3              |
+-----------------------+------------+-----------+--------------------+

Power required for each helical drag bit was based on a 5 mm wide cutter
that cuts a 1.27 mm deep groove in the rock. The cutters are set along a
helical pitch of 20 mm. The pilot bit advance is on the order of 0.1 mm
per rotation. The rotation of the pilot bit is 100 RPM while the Helical
Drag Bit Flight rotates at about 30 RPM. As noted, the power required
per meter is listed as the power required to be supplied to the motor.
The motor is expected to be only 65% efficient and this was taken into
account. Using the power requirements shown in Table 5, and the
available days for drilling, the depth predictions for each of the 5
cases is shown in Figure 4. The performance predictions are bounded by a
conservative case of drilling the entire hole through hard rock (the
hard rock unconfined compressive strength value is typical of Basalt,
about 200 MPa). A more aggressive prediction is that of drilling through
soft rock (the soft rock unconfined compressive strength value is
typical of weak limestone, about 50 MPa).

![](media/image62.jpeg){width="2.788976377952756in"
height="2.091732283464567in"} **Figure 4. The LRFD performance
predictions for drilling through various strength solid rock. 65% motor
efficiency was used in making depth predictions. Power margins were
reserved for heaters and controllers. Mass was reserved for activities
other than drilling. Changes to these values will effect performance
predictions. Reductions in margins provide increase in depth
capability.**

# **RELEVANT TEST DATA**

# 

Many components of the LRFD are in regular use in the drilling industry
or related fields today. One major deviation from conventional drilling
is that of helical cutter flights. The flights are a significant
deviation from traditional drilling technology and require careful
study, development, and testing. To-date the helical cutters have
undergone extensive theoretical analysis (GRI Report 98/0266 "Helical

# Drag Bit: A Self-Advancing Energy Efficient Drill Bit", and NAS5-00100 Final Report "The Low Reaction Force Drill"). These analyses were![](media/image63.png){width="3.1661417322834646in" height="2.0791338582677166in"}![](media/image64.jpeg){width="3.4043307086614174in" height="2.251574803149606in"}![](media/image65.jpeg){width="2.0in" height="2.25in"}![](media/image66.jpeg){width="2.666535433070866in" height="2.2in"}chips.

The results of groove cutting and ridge breaking tests were used along
with the theoretical analysis to design and build a first set of
prototype helical cutters as shown in Figure 7. Drilling with the
helical cutters in predrilled pilot holes was conducted in limestone of
roughly 30 MPa compressive strength and diabase of roughly 300 MPa. The
cutters successfully created threaded grooves in the rock as shown in
Figure 8. Torque measurements made during drilling confirmed cutting
force predictions and thus power consumption per meter advance.

*Several individual components of the LRFD have been tested, but not as
an integrated system to-date. Table 6 lists LRFD components with
comments on the state-of-the-art and existing test data, and comments on
the need for further tests and integrated testing. Given the importance
of mass and energy constraints, all components will need analysis of the
materials used in construction to ensure durability and minimum mass in
a cost effective design.*

+---------------+---------------------+--------------+----------------+
| **Table 6.    |                     |              |                |
| LRFD          |                     |              |                |
| components    |                     |              |                |
| and their     |                     |              |                |
| relevant test |                     |              |                |
| data          |                     |              |                |
| co            |                     |              |                |
| mpleteness.** |                     |              |                |
+---------------+---------------------+--------------+----------------+
|               | *                   | **Existing   | **Need for     |
|               | *State-of-the-art** | Test Data**  | further        |
|               |                     |              | testing**      |
+---------------+---------------------+--------------+----------------+
| ### Batteries | Known art.          | Extensive    | Selected       |
|               | Off-the-shelf       | data         | equipment      |
|               | technology in a     | available.   | needs to be    |
|               | variety of          |              | integrated     |
|               | dimensions, and     |              | into the       |
|               | performance         |              | system and     |
|               | characteristics     |              | tested.        |
|               | suitable for the    |              |                |
|               | LRFD.               |              |                |
+---------------+---------------------+--------------+----------------+
| **Down-hole   | Known art.          | Extensive    | Selected       |
| electric      | Off-the-shelf       | data         | equipment      |
| motors**      | technology in a     | available.   | needs to be    |
|               | variety of          |              | integrated     |
|               | dimensions, and     |              | into the       |
|               | performance         |              | system and     |
|               | characteristics     |              | tested.        |
|               | suitable for the    |              |                |
|               | LRFD.               |              |                |
+---------------+---------------------+--------------+----------------+
| **Down-hole   | Known art. However, | Performance  | Prototype gear |
| planetary     | specific gear train | data         | train must be  |
| gears**       | must be designed    | available on | tested under a |
|               | and built for this  | existing     | variety of     |
|               | application         | down-hole    | temperature    |
|               |                     | gear trains. | and loading    |
|               |                     |              | conditions.    |
+---------------+---------------------+--------------+----------------+
| **Pilot       | Known art.          | Extensive    | Selected       |
| bits**        | Off-the-shelf       | data is      | equipment      |
|               | technology in a     | available on | needs to be    |
|               | variety of          | basic drag   | integrated     |
|               | dimensions, and     | bits that    | into the       |
|               | performance         | are suitable | system and     |
|               | characteristics     | for the      | tested.        |
|               | suitable for the    | LRFD.        |                |
|               | LRFD.               |              |                |
+---------------+---------------------+--------------+----------------+
| **Auger       | Known art. Auger    | Extensive    | Selected       |
| bailing**     | bailing is used in  | data is      | equipment      |
|               | a broad range of    | available.   | needs to be    |
|               | applications and is |              | integrated     |
|               | readily available   |              | into the       |
|               | for adaptation to   |              | system and     |
|               | the LRFD.           |              | tested.        |
+---------------+---------------------+--------------+----------------+
| **Helical     | New Technology.     | Basic single | Prototype      |
| flight        | Similar to          | and parallel | flight         |
| excavation**  | self-taping sheet   | groove       | performance    |
|               | metal screws, this  | cutting in   | testing in     |
|               | is a new technology | rock and     | rock and       |
|               | applied to rock and | ridge        | regolith is    |
|               | regolith drilling.  | breaking has | currently      |
|               |                     | been studied | being carried  |
|               |                     | (DRI         | out. True      |
|               |                     | report). Bit | field          |
|               |                     | wear test    | conditions and |
|               |                     | data is      | deep drilling  |
|               |                     | abundant.    | performance    |
|               |                     |              | must be        |
|               |                     |              | tested.        |
+---------------+---------------------+--------------+----------------+
| **Helical     | New Technology.     | Self-        | Prototype      |
| flight        | Similar to rotating | advancement, | flight         |
| advancing /   | a bolt in a         | Weight on    | performance    |
| Weight on bit | threaded hole, the  | bit, and     | testing in     |
| / Rotational  | bit will create     | reaction     | rock and       |
| reaction      | weight on bit and   | force        | regolith is    |
| force**       | self- advance in    | development  | currently      |
|               | the hole with       | by           | being carried  |
|               | rotation.           | stationary   | out. Each of   |
|               | Stationary          | components   | the critical   |
|               | components will     | has not been | performance    |
|               | provide reaction    | tested.      | criteria       |
|               | force against rock  |              | described will |
|               | or regolith.        |              | be evaluated.  |
+---------------+---------------------+--------------+----------------+
| **Bucket      | Known art. Used in  | Basic        | Selected       |
| bailing**     | a broad range of    | technology   | equipment      |
|               | applications and    | of known     | needs to be    |
|               | readily available   | performance. | integrated     |
|               | for adaptation to   |              | into the       |
|               | the LRFD.           |              | system and     |
|               |                     |              | tested.        |
+---------------+---------------------+--------------+----------------+
| **Control     | Known art. However, | None to      | Prototype      |
| circuitry**   | specific gear train | date.        | equipment      |
|               | must be designed    |              | needs to be    |
|               | and built for this  |              | integrated     |
|               | application.        |              | into the       |
|               |                     |              | system and     |
|               |                     |              | tested.        |
+---------------+---------------------+--------------+----------------+
| **Control     | Known art. However, | None to      | Prototype      |
| software**    | specific gear train | date.        | equipment      |
|               | must be designed    |              | needs to be    |
|               | and built for this  |              | integrated     |
|               | application.        |              | into the       |
|               |                     |              | system and     |
|               |                     |              | tested.        |
+---------------+---------------------+--------------+----------------+
| **Lining**    | Novel lining        | Some novel   | Prototype      |
|               | systems are         | systems have | equipment      |
|               | proposed.           | been tested. | needs to be    |
|               |                     |              | integrated     |
|               |                     |              | into the       |
|               |                     |              | system and     |
|               |                     |              | tested.        |
+---------------+---------------------+--------------+----------------+
| **Lining      | Likely to be New    | Installation | Prototype      |
| mechanism**   | Technology in order | equipment    | equipment      |
|               | to meet mass and    | must be      | needs to be    |
|               | installation power  | built and    | integrated     |
|               | constraints.        | tested.      | into the       |
|               |                     |              | system and     |
|               |                     |              | tested.        |
+---------------+---------------------+--------------+----------------+

**HOLE STABILIZATION**

Another key development that will be necessary for the successful
deployment of the LRFD is hole lining or stabilizing technology since it
is possible that drilling will need to be conducted in unconsolidated
material. A variety of lining techniques have been used in association
with other novel drilling techniques including slip lining, Tyvek
enhanced slip lining, compaction, and grouting. A technique that is
believed to be well suited to use with the LRFD, due to its low mass and
low power consumption, is that of a segmental lining that is shipped in
a single flat sheet roll of metal or plastic material. The lining system
involves paying out and cutting a specific length of the sheet material
while simultaneously bending it into a tube of smaller diameter than the
diameter of the hole. The bent sheet has overlapped edges with
compatible male-female coupling capability so that when the lining is
expanded to maximum hole diameter at depth the sheet forms a tube that
provides resistance to hole collapse as drilling advances. Clearly hole
stabilization is a technology unto itself that must be studied closely
in view of potential drilling on Mars.

**SAMPLING**

#  **Size:** As configured in all cases, the LRFD will recover chips with dimensions of about 15 mm x 2-3 cm (greater than 1 cm^3^). 

# 

# **Location:** The origin of individual chips will be known regularly to within 1 meter (5cm accuracy of location can be accomplished by selective sampling). The chips can be easily isolated down-hole or when retrieved to the surface but the actual hardware for isolation has not been identified in this exercise. 

# 

# **Time:** The time required to retrieve chips from the down-hole environment will vary depending on the depth of the sample. For depths on the order of 200m the retrieval process may take as long as 2 hours. For depths on the order of 1000m, retrieval may take as long as 0.5 sols. Faster retrieval rates from depth are possible and are proportional to the availability of power.

**Temperature:** The LRFD generates very little heat due to the
fundamental characteristic of drilling with a shear pick. The pick drags
against the surface of the rock at relatively low rpm when compared to
grinding methods of drilling such as core drilling. The temperature at
the pick/rock interface is expected to stay below an overall change in
temperature of 50° C. Heat rejection is from the bit to the rock and
atmosphere. Laboratory and field experiments with components of the LRFD
demonstrate that no other cooling is required.

# **DOWN-HOLE SCIENCE**

The LRFD will easily accommodate down-hole sensors for making in-situ
measurements. Sensors can be used between advances of the drilling
operation. Of special note is the fact that the LRFD proposed finished
hole diameter is on the order of 52 to 85mm depending on the LRFD
configuration used. This relatively large hole size will accommodate a
large range of sensors including long-term monitoring for moisture and
seismic activity. UTD has collaborated with the Naval Research
Laboratory to explore down-hole instrumentation for use on Mars.

**TECHNOLOGY DEVELOPMENT**

Based on the analysis and critical component testing done to date, the
LRFD is considered to be in the Technology Development readiness level
of 3 (analytical & experimental critical function and/or characteristic
proof-of-concept) as defined by NASA.

Four specific development areas must be fully pursued to advance to the
next readiness level:

1.  Helical cutter - configuration refinement, construction, testing and
    demonstration (currently in process.)

2.  Planetary gears - design, assembly, testing and demonstration.
    (Vendors identified.)

3.  Hole stabilization - equipment development and testing. (Potential
    techniques explored.)

4.  System integration and testing -- Laboratory breadboard testing of
    the complete system followed by field-testing in harsh environment
    (Technology readiness level 4 in laboratory, technology readiness
    level 5 completed when field tested).

# **RECOMMENDED SCHEDULE**

It is recommended that technology development and testing begin
immediately on one or several drilling technologies to ensure
appropriate technology is available as an option for future missions.
The mass and power constraints posed by drilling on bodies other than
earth are sufficiently different that it should not be assumed that
general drilling technology development for earthly applications will
produce technologies relevant to extraterrestrial applications.

Figure 4 shows the recommended schedule of development and testing of
the LRFD. Only main tasks are shown to provide an overall sense of the
development path.

# **COST**

The approximate cost of the proposed development program to take the
system through Technology Readiness Level 6 is \$2- \$3 M.

# **PROPRIETARY CONSIDERATIONS**

UTD recognizes the commercial potential and proprietary nature of the
technology described in this report. Most rights have been reserved
through a U.S. patent held by UTD Incorporated. UTD is willing to give
NASA a broad license for space-based application of the technology
covered by the patent in exchange for NASA sponsorship of UTD to perform
integration and demonstration of the technology for NASA applications.

![](media/image67.pct)

# **Cited and Un-cited References** 

Amini, A., J. Shenhar, and E.L. Foster, Helical Drag Bit -- A Self
Advancing Energy Efficient Drill Bit --Phase I Feasibility Study, Gas
Research Institute, CN. 5097-210-4115, 1998

Bourgoyne, A. T., K. K. Millheim, M. E. Chenevert, and F. S. Young,
Applied Drilling Engineering, Society of Petroleum Engineers,
Richardson,TX, 1991.

Chugh, C. P., Manual of Drilling Technology, Rotterdam: A.A. Balkema,
1987.

Clifford, S. M., "The Lithology and Volatile Stratigraphy of the Martian
Crust: A Review of Current Speculation, Lunar and Planetary Institute,
Houston, TX, 2000.

Earth, Moon, and Planets - An International Journal of Comparative
Planetology: See in particular - vol. 77 (1997-1998), Martian Dust
Storms: A Review: Walter Fernandez.

Eskin, M., W. C. Maurer, and A. Leviant, Former-USSR R&D on Novel
Drilling Techniques, Maurer Engineering, 1995.

Heinz, W. F., Diamond Drilling Handbook - First Edition, South African
Drilling Association, Johannesburg, Republic of South Africa, 1985.

Hill, J. L., B. Turner, J. Shenhar, S. Solga, The Low Reaction Force
Drill, Final Report, NASA SBIR, Contr. NAS5-00100, 2000.

Kishoni, D., Limestone Testing (Groove Cutting In Limestone As Input To
Helical Drag Bit Design), Denver Research Insitute, CMI-F-9821, 1998

Lunar and Planetary Science XXVIII, 1997, various papers presented at
conference sponsored by NASA (see description of stratified rocks on
page 807, in particular).

Maurer, W. C., Advanced Drilling Techniques, Petroleum Publishing Co.,
Tulsa, OK, 1980.

Maurer, W. C., Novel Drilling Techniques, Pergamon Press, London, 1968.

McSween et al., Chemical, multispectral, and textural constraints on the
composition and origin of rocks at the Mars Pathfinder landing site,
April 1999, Journal of Geophysical Research, vol. 104, No. E4, pp.
8679-8715.

Moore, P. L. et al., Drilling Practices Manual, Petroleum Publishing
Co., Tulsa, OK, 1974.

National Research Council, Drilling and Excavation Technologies for the
Future, National Academy Press, Washington, D. C., 1994.

U. S. Patent \# 5,641,027 Drilling System, held by UTD Incorporated,
1997. (Patent on the basic helical drag bit technology described as a
major component of the LRFD in this white paper. E.L. Foster, principal
inventor).

**Responses to questions and comments arising from presentation of the
Low Reaction Force Drill at the Mars Drilling Feasibility Workshop at
the Lunar and Planetary Institute (LPI) in Houston, Texas, February
27-28, 2001.** Comments that were recorded at the workshop are shown in
black typeface. Responses to the comments are shown in blue typeface.

-   Inclusion of mass margin in estimates. This point was made during
    the presentation to reinforce the need for other approaches to
    consider future requests for mass and power reductions. The fact
    that we had included margins was considered a strength of the
    approach.

-   Test hole went 22 inches. This point was made because a member of
    the audience was trying to understand why we were showing a picture
    of threads still existing in the hole (Figure 8 in this white
    paper). It was explained that this was shown to emphasize the NEW
    part of drilling that the LRFD system offers and that this was not
    representative of what the borehole looks like after the threads had
    been stripped.

-   What happens if threads break irregularly? It was shown during the
    presentation that a robust auger blade attempts to break the threads
    in bending closer and closer to the borehole wall. If any rock ridge
    remains it is ultimately removed by the passage of the auger blade.

-   What happens if cutter breaks (problem). Initial response to this
    question indicated that this would be a problem. However, the cutter
    arms were strength designed to withstand the force of pulling the
    whole bit straight out of the hole and break off all rock ridges. It
    is important to note that even if one or two arms break, this will
    probably not be a problem due to the small contribution that each
    arm makes to deepen the groove.

-   Gear head efficiency. Question asked recognizing that we were
    drilling at very slow rpm. The audience did not find exception with
    the statement that gear head inefficiency was probably covered in
    our conservative 65% efficiency applied to the motor, and our use of
    conservative power margins that had been deemed to be not necessary
    by previous presenters. Gear head efficiency drops with the
    differential between motor rpm and desired bit rpm. The optimal rpm
    for the LRFD has not been established. It is pointed out however
    that it should be able to advance more quickly (and does) than core
    drilling since coring is a grinding -- high rpm method of drilling,
    and the LRFD relies solely on shear drilling -- a much lower
    temperature drilling technology.

-   How far can you drill before emptying basket? A meter in length is
    probably a reasonable number but longer lengths may be possible. The
    concern was that this might be a very heavy tube to pull out.
    However, it was pointed out that cuttings large or small are no
    heavier than core, and typically lower in density.

-   Instruments may pick up helical structure. This was a follow up
    statement to the statement about the depth of the test hole. This is
    where his line of questioning was cleared up regarding the final
    profile of the hole. It was then understood by all participants that
    instruments would likely not be affected by any remnant helical
    structure of the hole since the hlical structure is largely removed.

-   Lot of pieces, complex. This is generally true. Although a careful
    analysis of each of the other techniques proposed will reveal that
    all drilling systems are at least equal in complexity and most
    others have unproven components whereas all components of the LRFD
    are currently used in the industry in some fashion or have recently
    been feasibility tested and proven. Arnold Law of Christensen made a
    strong point that coring and core handling is a complex process.

-   Brushless motors can be hollow. A positive comment offered by
    Baker-Hughes team member suggesting that the proposed system
    components in the LRFD are proven technology and offer flexibility
    in design for performance optimization.

-   Cuttings are pulled up. This comment was simply a note of
    clarification. Wire line systems for various uses are used every day
    in the drilling industry with minimal maintenance requirements.

-   Can cutters be kept in place during drilling? Yes. In fact they do
    stay in place during drilling and provide reaction force for each
    other in a step by step drilling process that allows the system to
    advance through multiple media scenarios without relying on reaction
    force from the surface.

-   (An unrecorded but relevant question) What is the expected wear rate
    of the bit? UTD worked with Smith Bits International, a major
    developer, manufacturer and distributor of bits for the oil and gas
    industry to assess the wear characteristics of the helical drag bit.
    Their research shows that the LRFD should be able to drill
    kilometers of depth before requiring bit replacement as shown in the
    following graph of their empirical data from thousands of kilometers
    of drilling experience with PDC
    inserts.![](media/image9.pct){width="6.500694444444444in"
    height="2.9402777777777778in"}

**Conclusions**

A drilling concept has been presented that has undergone extensive
analysis and feasibility testing. The salient characteristics of the
system include:

-   **LRFD Bit design relies on proven technology -- the interaction of
    a pick with rock is the most thoroughly studied mechanical
    excavation technique known to man and serves as the basis for the
    LRFD bit system.**

-   **Low temperature drilling -- basic characteristic of shear bit
    drilling when compared to grinding methods such as coring. The
    system is also amenable to low rpm and low drilling rate for even
    greater temperature control.**

-   **No cutting fluids - if used with auger/bailing bucket return.**

-   **Self-advancing through sand, regolith, soft and hard rock
    transitions -characteristic of bit system design.**

-   **Manageable complexity -- The bit system proposed is more complex
    than alternative methods. However, as a complete system the
    complexity is no more than any other drilling system described at
    the workshop. Coring and core handling is a complex process and
    applying thrust down-hole is complex as described by alternative
    approaches.**

-   **Surface reaction force minimal - mass of drilling system is
    sufficient.**

-   **Low drilling system mass - less than 100 kg for hole depths 2 m -
    1 km.**

-   **Low energy consumption - characteristic of rock comminution, 200 m
    depth within 120 sols at 100 Watt-hrs per sol delivered to drilling
    system.**

-   **Sample return to surface - large rock chips greater than 1 cm^3^,
    adequate for scientific analysis, of known horizon origin.**

-   **Real-time down-hole instrumentation compatible - hole size
    sufficient for instrumentation (greater than 50 mm in diameter),
    direct access to rock available for instruments.**

-   **Configurable with many hole-casing techniques - cast in place,
    segmental, continuous, etc.**