**NATIONAL AERONAUTICS AND SPACE ADMINISTRATION**

***MARS SURVEYOR '98 PARTICIPATING SCIENTIST***

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**ANNOUNCEMENT OF OPPORTUNITY**

***PROPOSAL INFORMATION PACKAGE***

**TABLE OF CONTENTS**

**page**

**1.0 INTRODUCTION 3**

1.1 Document Overview 3

1.2 Mars Surveyor Program 3

> 1.3 Mars Surveyor '98 Operations Management 5
>
> 1.4 MCO Payload Overview 6
>
> 1.5 MPL Payload Overview 7

**2.0 MISSION SCIENCE 9**

> 2.1 Mars Surveyor 1998 Mission Strategy 9
>
> 2.2 Mars Surveyor 1998 Mission Measurement Objectives 10

**3.0 MISSION PHASES 11**

> 3.1 Landing Site Adjustment Maneuver 13
>
> 3.2 MCO Orbital Insertion and Aerobraking 13
>
> 3.3 MPL Entry, Descent and Landing 15
>
> 3.4 MPL Landed Operations 15
>
> 3.5 MCO Lander Support Phase 18
>
> 3.6 MCO Mapping Mission 18

**4.0 SCIENCE INVESTIGATIONS: MARS CLIMATE ORBITER 21**

> 4.1 Pressure Modulator Infrared Radiometer (PMIRR) 21
>
> 4.2 Mars Color Imager (MARCI) 24

**5.0 SCIENCE INVESTIGATIONS: MARS POLAR LANDER 26**

> 5.1 Mars Descent Imager (MARDI) 26
>
> 5.2 Mars Volatiles and Climate Surveyor (MVACS) 26
>
> 5.2.1 Surface Stereo Imager (SSI) 27

5.2.2 Robotic Arm (RA); Robotic Arm Camera (RAC), Surface Thermal Probe
(STP) 27

> 5.2.3 Meteorological Package (MET) 28
>
> 5.2.4 Thermal and Evolved Gas Analyzer (TEGA) 29
>
> 5.2.5 Potential Areas of Emphasis for Participating Scientists with
> MVACS 30
>
> 5.3 LIDAR 30

**1.0 INTRODUCTION**

**1.1 Document Overview**

This Proposal Information Package (PIP) document provides information
describing the Mars Surveyor 1998 Mission, which includes activities
associated with both the Mars Climate Orbiter (MCO) and the Mars Polar
Lander (MPL). This PIP is provided in support of the Mars Surveyor '98
(MS'98) Announcement of Opportunity for Participating Scientists (AO
99-OSS-02).

**1.2 Mars Surveyor Program**

The National Aeronautics and Space Administration (NASA) has initiated a
long-term systematic program of Mars exploration, the Mars Surveyor
Program (MSP). The highest priority scientific objectives of this
program are to:

-   Search for evidence of past or present life;

-   Understand the climate and volatile history of Mars;

-   Assess the nature and inventory of resources on Mars.

The common thread of these objectives is water: past and present sources
and sinks; exchanges between subsurface, surface and atmospheric
reservoirs; and the change of volatiles over time.

The goal of the MSP is to carry out low-cost missions, each of which
provides important, focused, scientific return, and which will in sum
constitute a major element of the scientific exploration of Mars. A
series of lander and orbiter spacecraft are being launched at each
favorable Mars launch opportunity, which occur approximately every 26
months. In 1997 the MSP launched the Mars Global Surveyor (MGS), which
together with the launch of the Discovery Program's Mars Pathfinder
lander, initiated the new era of Mars exploration.

In the 1998-1999 launch opportunity, the MSP successfully launched the
following spacecraft, which are now in flight to Mars:

-   Mars Climate Orbiter (MCO) launched on December 11, 1998

-   Mars Polar Lander (MPL) launched on January 3, 1999.

The Mars Polar Lander also carries two New Millennium Program (NMP)
microprobes as the Deep Space 2 (DS2) Mission. These probes will
separate from MPL prior to its entry into the Martian atmosphere, then
fall through the atmosphere (without parachutes or rockets to slow their
entry) and crash into the surface, with the probe forebodies penetrating
up to a meter deep into the Mars surface. A Science Team has been
previously selected for the DS2 mission and no participation is
solicited here. However, the short-lived DS2 probes will be located
approximately 100 km further north (equatorward) of the MPL touchdown
point and will themselves search for the presence of subsurface water
ice and attempt to characterize subsurface soil thermal properties.
Thus, complementary data will be obtained by the DS2 and MPL surface
packages (and by MCO and MGS).

Future missions will culminate in the return of samples of Martian rocks
and soil to Earth. The focus of the MS'98 element of the MSP is to
advance our understanding of the volatile and climate history of Mars
through systematic mapping of the Mars seasonal cycles of weather, dust,
water and carbon dioxide by remote sensing from orbit and through
exploration in situ at a landed site on the layered terrain near the
Martian south pole.

**1.3 Mars Surveyor '98 Operations Management**

The Mars Surveyor Program is managed by the Jet Propulsion Laboratory
(JPL), California Institute of Technology, for NASA's Office of Space
Sciences. A JPL development project oversaw the design, build, and
testing of the MCO and MPL by Lockheed-Martin Astronautics (LMA) in
their Denver, Colorado, facilities, launch of the spacecraft onboard
separate Boeing Delta 7425 launch vehicles from the Cape Canaveral Air
Force Station in Florida, and operation of the spacecraft during the
first month of flight, which saw successful deployment of solar arrays,
establishment of telecommunication links and spacecraft flight control,
and execution of trajectory course correction maneuvers that corrected
for launch bias and injection errors.

Now in mid-cruise, MCO and MPL are operated by a spacecraft flight team
at LMA and flight operations teams at JPL managed by the Mars Surveyor
Operations Project (MSOP). This JPL-LMA team is also responsible for
operation of MGS, even as the team assists development of future
spacecraft elements of the Mars Surveyor Program. The MSOP also funds
and manages operations by the science investigations and the initial
analysis of data returned by the spacecraft and their scientific
instruments.

Science investigations on the Mars Climate Orbiter and Mars Polar Lander
will largely be conducted remotely through the principal investigator's
home institution. This includes both commanding of the science
instruments and analysis of the returned instrument engineering and
scientific data.

**1.4 MCO Payload Overview**

The Mars Climate Orbiter carries the following science instruments:

-   Pressure Modulator Infrared Radiometer (PMIRR);

-   Mars Color Imager (MARCI).

PMIRR is essentially a build-to-print copy of the atmosphere sounder and
polar radiative balance mapper flown previously on Mars Observer. PMIRR
will provide vertical profiles of temperature, dust and water vapor over
the planet each day, in addition to monitoring reflected sunlight and
thermal infrared radiance. MARCI consists of two camera systems sharing
common components. The Wide Angle camera will provide daily synoptic
mosaics of the Mars atmosphere and surface, including observations at
ultraviolet wavelengths, while the Medium Angle camera will image the
surface in several visible and near-infrared bands at moderate spatial
resolution (40-m at nadir).

The instruments are described in more detail in separate sections. Both
PMIRR and MARCI are mounted so that their (vertical) z-axis is nadir
pointed, even though the spacecraft z-axis is tilted somewhat to
minimize gravity gradient torques and fuel usage for station-keeping on
orbit. PMIRR has a two-axis scan mirror that enables it to look anywhere
in a quadrant below the spacecraft and from the aft limb to the
("sunward") side limb. MARCI has no scanning capability; instead MARCI
utilizes a "push-frame" approach in which adjacent spectral coating
bands on its charged-coupled detectors (CCDs) are overlapped by MCO's
motion along the spacecraft ground-track and by appropriate timing of
image acquisition.

MCO also carries a Radio Relay (UHF) for communication with surface
landers, including the Mars Polar Lander and potentially the MSP '01
Lander now being built. Unlike MGS, MCO does not carry an ultrastable
oscillator (USO) and so no radio science investigation was selected.
However, entry occultations, as MCO disappears behind the planet, may be
candidates for analysis.

An additional source of engineering data can provide information about
the Martian upper atmosphere. During aerobraking, current plans are to
return 1-second samples of the MCO accelerometer output during each
aeropass, as the orbiter dips into the upper atmosphere of Mars (with
periapsis likely to be ≥ 110 km altitude) to slow its speed and thereby
lower its apoapsis, ultimately achieving a nearly circular and polar
orbit. These accelerometer measurements can be related to atmospheric
density and temperature of the upper atmosphere.

**1.5 MPL Payload Overview**

The Lander payload includes, by design and selection, an integrated
suite of instruments, under the auspices of a single Principal
Investigator and his Co-Investigators:

-   Mars Volatiles and Climate Surveyor (MVACS)

-   Surface Stereo Imager (SSI) with Magnetic Targets

-   Robotic Arm and Robotic Arm Camera (RA, RAC)

-   Meteorology Package (MET)

-   Water Vapor and Isotope Tunable Diode Laser (TDL)

-   Thermal / Evolved Gas Analyzer (TEGA)

-   Surface Thermal Probe (STP)

    and two individually selected instruments:

-   Mars Descent Imager (MARDI)

-   LIDAR (with Microphone)

During the Lander\'s descent to the surface, MARDI will acquire a series
of nested images at ever higher spatial resolution, beginning after
parachute deployment and heat shield jettison (see below).

MPL will soft-land on the surface at polar latitudes (74-77S) in the
southern hemisphere of Mars, where the MVACS integrated instrument
suite, together with a LIDAR experiment provided by the Russia's Space
Research Institute (IKI), will perform landed investigations. The LIDAR
will provide the altitudes of low-altitude (\< 5 km) hazes and clouds
using active ranging. It also contains a microphone for exploring the
acoustic environment of Mars. Because of data volume constraints, a
typical LIDAR/microphone mode stores for readout and return a ten-second
record of the "loudest" (i.e., most detectable) sound detected during a
longer sampling period.

MVACS will use its Robotic Arm to: 1) provide access to the surface and
subsurface, by trenching into the surface; 2) emplace the Surface
Thermal Probe to characterize heat capacity; 3) use the Robotic Arm
Camera to view sidewalls of the trench and to characterize soil samples;
and 4) to obtain soil samples for the TEGA. The SSI will also observe
sky brightness and estimate atmospheric column abundances of dust,
condensate and water vapor. Water vapor concentration is also measured
locally by the atmospheric TDL. Meanwhile, local air temperatures and
winds will be measured by devices located on two meteorological masts,
one vertical above the MPL deck and the other slanting down near the
(atmospheric) surface layer.

**2.0 MISSION SCIENCE**

The Mars Surveyor 1998 Missions were designed, and their payloads
selected, to address the science theme \"Volatiles and Climate History\"
on Mars, thereby directly addressing the climate-history and resource
themes of the Mars Surveyor Program, while supporting the life-on-Mars
theme through characterization of climate change and its evolving impact
on the distribution of water.

**2.1 Mars Surveyor 1998 Mission Strategy**

To address the "Volatiles and Climate History" theme within the
programmatic constraints of cost and affordable launch capabilities, the
Mars Climate Orbiter and Mars Polar Lander Missions pursued the
following scientific strategy:

-   Use seasonal and diurnal cycles of Dust, Water and Carbon Dioxide to
    understand [Processes]{.underline} of climate change over longer
    time scales;

-   Characterize global atmospheric structure and circulation to
    elucidate roles of [Atmospheric Transport]{.underline} of Volatiles
    and Dust;

-   Land on, and explore, a site having [Physical Evidence]{.underline}
    of ancient climates, atmospheric evolution and more recent, possibly
    periodic climate change;

-   Locate surface [Ice Reservoirs]{.underline} and search for local
    [Sub-Surface Ice;]{.underline}

-   Acquire data needed to validate and extend [Model
    Simulations]{.underline} of climate processes and climate change;

-   Emphasize [Comparative Study]{.underline} of the climates of Earth
    and Mars and their potential implications for origin and development
    of life.

**2.2 Mars Surveyor 1998 Mission Measurement Objectives**

Given the scientific strategy outlined above, the major scientific
measurement objectives for the Mars Surveyor Program 1998 Missions are
to:

-   Systematically observe the thermal structure and dynamics of the
    global atmosphere and the radiative balance of the polar regions,
    thereby providing a quantitative climatology of weather regimes and
    daily to seasonal processes;

-   Determine the variations with time and space of the atmospheric
    abundance of dust and of volatile material (i.e., carbon dioxide and
    water, both vapor and ice) for one full Martian year;

-   Identify surface reservoirs of volatile material & dust and observe
    their seasonal variations; characterize surface compositional
    boundaries and their changes with time; search for near-surface
    ground ice in the polar regions;

-   Explore and quantify the climate processes of dust storm onset and
    decay, of atmospheric transport of volatiles and dust, and of mass
    exchange between the atmosphere, surface and subsurface;

-   Search for evidence characterizing ancient climates and more recent
    periodic climate change.

**3.0 Mission Phases**

The MCO and MPL spacecraft are now in the second half of their journey
to Mars. Key mission events and phases remaining are (see schedule
below):

-   MPL Site Adjustment Maneuver (SAM) Early September, 1999

-   MCO Mars Orbital Insertion (MOI) September 23

-   MCO Aerobraking (A/B) Sept. 25 - Nov. 25

-   MPL Entry, Descent and Landing (EDL) December 3

-   MPL Landed Operations Dec. 3 - Mar. 1, 2000

-   MCO Lander Support Phase (LSP) Dec. 3 - Mar. 1, 2000

-   MCO Mapping Mission Mar. 1, 2000 - Jan. 15, 2002

-   MCO Relay Phase Jan. 15, 2002 - 2003

The mission overview on the next page shows the key milestones,
including the arrival of the MS'01 Lander and the overlapping MGS
mapping mission.

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**3.1 Landing Site Adjustment Maneuver**

MPL is currently targeted to 75S, 200W with a 2-sigma landing error
ellipse approximately 200 km down track (± 100 km, principally
north-to-south) and 20 km cross-track (± 10 km, west-to-east). A final
target landing site, located in the target zone 74S-76S; 170W-230W will
be selected based on imaging data from past spacecraft missions (Mariner
9 and Viking) and on preliminary data from the MGS Mars Orbiter Laser
Altimeter (MOLA) and Mars Orbiter Camera (MOC). This site will be
selected by August, 1999, and a Site Adjustment Maneuver must be
performed in cruise by MPL by early September. The target zone is the
most northern (equatorward) part of the south polar layered terrain and
is likely to be free of seasonal carbon dioxide frost at the time of
arrival (areocentric longitude Ls = 256). The poleward limit of the
target zone is due to atmospheric entry angle ("skip-out") and entry
atmospheric heating constraints.

**3.2 MCO Orbital Insertion and Aerobraking**

At the present time, no observations by the MARCI or PMIRR are planned
during this mission phase, which follows Mars approach images to be
taken by MARCI in late cruise (\~ Sept. 5). PMIRR cannot observe because
its passive radiator is directed into the flow during each aeropass, and
so its radiator door remains in the vent (nearly closed) position to
protect the radiator from contamination and from inadvertent solar
illumination during spacecraft positioning for aerobraking.
Accelerometer (engineering) data will be recorded by the LMA spacecraft
team and estimates of periapsis density will be reconstructed by the JPL
MSOP navigation team. MCO aerobraking will be conducted at a time when
observations by the MGS science payload and spacecraft will be routinely
acquired as part of the MGS mapping mission.

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**3.3 MPL Entry, Descent and Landing**

During descent (see above), MPL will not record individual accelerometer
readouts, but will record integrated state position vectors, based on
the higher-rate sampling accelerometer measurements. These state
positions will nominally be returned during the first hours after
landing. The day of landing (Dec. 3, 1999) is designated Sol 0 (a sol is
a martian day). MPL will land at \~ 5 a.m., Mars local time.

The Mars Descent Imager (MARDI) will acquire up to a dozen images during
descent of MPL, following jettison of the heat shield at an altitude
less than 8 km above the surface. The number of images acquired depends
in part on atmospheric conditions at the time of entry, as these
conditions (and the final choice of landing target latitude) may cause a
somewhat shorter or longer descent time in the atmosphere, with longer
times associated with longer (and more poleward) atmospheric flight
paths. The quality of images during powered descent, from approximately
1 km altitude to the ground, is unknown, as the camera will be looking
through rocket plumes from three banks of four rocket thrusters each,
firing in rapidly pulsed sequences orchestrated by the onboard guidance.
Close to the surface, there will also be dust raised up into the
atmosphere by the multiple rocket exhausts and thermal plumes impinging
the surface.

**3.4 MPL Landed Operations**

The first few sols (i.e., Mars days) after touchdown of the MPL are
devoted to: (1) establishing radio communication with the MPL, first
through its direct-to-Earth (DTE) telecommunications system with the
medium-gain antenna, and then via relay through the MCO; and (2)
returning: a) the MARDI data, b) stowed and unstowed Surface Stereo
Imager elevation scans, c) descent and landed engineering data, and d)
initial environmental data acquired by the MET and LIDAR instrument
suites. Activities scripted for Sol 0 through Sol 2 are included in the
onboard spacecraft sequence. If the relay through MCO is not working,
the MPL spacecraft will automatically continue using an onboard
contingency sequence which routinely uses the DTE link while continuing
to try the MCO relay path. Commanded science sequences are initiated on
Sol 2 if operations are proceeding nominally.

MPL is a solar-powered lander with a relatively small battery system.
Even though the Sun will be above the horizon at these southern polar
latitudes during the late southern spring and early southern summer
seasons when MPL will be operating on the surface of Mars, the elevation
of the Sun changes throughout the day, with the period of high Sun
(referred to as "day") being the most optimum period for solar power
generation and thus operation of the lander and payload. The payload
will not normally be operated continuously through the night (i.e., the
period when the Sun is low on the horizon), but hourly observations are
anticipated on many nights, subject both to the power required by that
day's operations and the Martian environment, particularly the amount of
dust suspended in the atmosphere.

Due to power limitations, the direct-to-Earth (DTE) radio link will be
used sparingly, assuming that the MCO orbiter relay is working properly.
DTE sessions are planned during the first week of landed operations and,
assuming nominal success of the MCO relay path, on a weekly basis
thereafter. Later in the mission (\> Sol 25), MPL may use a special
meteorological observational sequence where it relies solely on the DTE
link for a week or so, enabling high-frequency observations by MPL and
simultaneous observations by MCO. MPL can return data to, and receive
commands from, Earth via the MCO relay. Use of the MCO does introduce
latency into the MPL data return, as MPL data is stored onboard the MCO
and returned during regularly scheduled downlinks from the MCO.

MPL data can also be returned to, but the spacecraft cannot be commanded
from, Earth using the MGS Mars Relay. Also, the battery operated DS-2
probes can return data only through MGS. Given their battery-only power
(no arrays) and thus finite lifetime, the DS-2 probes have been given
priority for the MGS relay, with MCO designated as the primary relay for
MPL. The orbit of MCO will be phased such that there will be up to four
UHF relay opportunities between MCO and MPL during prime operating hours
of the lander on each sol.

Following nominal return of descent and early landed data, it is
anticipated that full science operations will commence on Sol 2. Key
operational sequences to be conducted are: 1) low and high-resolution,
monochromatic and multi-spectral panoramas by the SSI of the local
landscape; 2) trenching of the Martian soil; 3) characterization of the
local meteorology and of surface and sub-surface magnetic, thermal and
reflectance properties; 4) eight TEGA analysis runs, utilizing soil from
different depths and possibly different locations within the Robotic Arm
workspace; 5) characterization of the overhead atmospheric opacity, both
as haze and as clouds; 6) exploration of the acoustic environment on
Mars (requiring "quiet" listening periods with minimal lander payload
activity, to prevent masking of uniquely Martian sounds).

Eventually, true sunset will occur at the MPL latitude, in mid-summer.
Reduced sunlight impacts both the thermal environment of the lander and
generation of power by its solar arrays. Furthermore, both elements may
be adversely affected by atmospheric hazes, whether composed of
suspended condensates or dust particles. While no explicit account of
dust accumulation on the solar arrays has been assumed, the aim is to
accomplish the bulk of the Lander activities (e.g., conduct most of the
TEGA sample analysis and complete an adequate multi-spectral panorama of
the landscape) within 30 sols of landing. Following the first month of
MPL activity, observations will be designed to capture essential aspects
of the seasonal cycle, to improve the spatial resolution of
multi-spectral imaging of the landscape, to continue digging deeper into
the terrain and to conduct the final TEGA sampling experiment(s).
Ultimately, the MPL batteries will fail to be recharged or some
component will break, perhaps due to extreme cold, ending the mission.
The expected lifetime of MPL operations on the surface of Mars is
expected to be approximately 60-90 sols.

*The pace and duration of science operational sequences depend
critically on the MPL landed power capability, particularly the
generating capability of the MPL solar arrays as affected by deployment,
orientation (shadowing), spacecraft tilt, and by the variable
atmospheric opacity.*

**3.5 MCO Lander Support Phase**

Following the end of aerobraking, and prior to the landing of MPL on
Mars, MCO will essentially be in its near-polar, circular mapping orbit,
although the final transfer to mapping orbit may be delayed until after
landing and early operations of MPL on the surface. During this mission
phase, MCO will give priority to the relay of commands to, and the
return of data from, the Mars Polar Lander.

Observations by MARCI may be conducted during this period, contingent
upon adequate data volume and the priority given multi-mission
operations activities. Both MARCI and PMIRR are affected by operation of
the UHF relay used to communicate with MPL, and there is currently a
flight rule which requires that these two instruments be off during
operation of the UHF relay. MARCI can turn on and off quickly, avoiding
the relay periods when used (up to four per sol), with the relay periods
ranging in duration from a few up to 15 minutes, accounting for warm-up
of the relay hardware. PMIRR, however, is not easily switched on and
off, as it requires several hours for its passively (i.e., radiatively)
cooled detector focal plane to reach operating temperatures, and for the
instrument optical path to stabilize at the desired temperature. Thus,
no PMIRR operations are planned until the MPL no longer needs relay
through MCO for extended periods.

**3.6 MCO Mapping Mission**

MCO will commence its mapping mission on March 1, 2000, and will
continue to support MARCI and PMIRR observations for one Mars year. If
MPL landed operations have ended prior to this date, MCO will begin
mapping operations earlier, but will continue to support instrument
observations until January 15, 2002. Should MPL still be operating at
the end of February, MPL will revert to the use of its DTE link and
possibly to data return by the MGS Mars Relay.

The Mapping Mission orbit will be a nearly frozen orbit, nominally at
405 km altitude. At the end of aerobraking, the local time of the MCO
orbit will be near 5 p.m. By choice of orbital inclination, a
"sun-drifting" orbit can be established, in which the mean local solar
time of the dayside descending equatorial node will "drift" to earlier
local times, with much of the mapping mission spent near 4 p.m./4 a.m.
local solar time, until Mars is once again near perihelion, when the
local time may move as early as 3 p.m./3 a.m. The major constraint on
the choice of this drift rate is the requirement to have sufficient
power to operate PMIRR, as well as MARCI, at aphelion and to operate the
UHF radio relay in early 2002 to support the MS'01 lander surface
operations. At present, the major restriction is posed by having MCO at
a true local solar time no [earlier]{.underline} than 4 p.m. at
aphelion. (Earlier local times would mean that MCO would not close
energy balance daily due to solar eclipse by Mars for significant
periods.)

*The final choice of sun-drift rates and local time variation will
depend upon actual performance of the MCO solar arrays and of orbit
evolution during MCO aerobraking.*

Originally designed for a 2 p.m. - 2 a.m. orbit, the MCO instruments are
affected by restriction to these later local solar times. For PMIRR,
there will be less contrast between surface and atmospheric
temperatures, which will complicate vertical profiling using on-planet
(including nadir) views, and there may be more atmospheric condensates
present near the evening terminator, limiting the ability of PMIRR to
observe the atmosphere near the surface and at the limb. MARCI is more
affected, in that it was designed to highlight spectral compositional
differences of the surface, which is not easily done at large view
angles. Furthermore, the illumination of the limb-to-limb cross-track
MARCI Wide Angle view is less symmetric at late afternoon local times ,
complicating the generation of a daily global mosaic. On the other hand,
the planned sun-drift orbit will provide MARCI observations at earlier
local times late in the mapping mission, and the combination of MCO and
MGS observations will provide much better coverage of diurnal
variations, which are a significant part of Mars meteorological
variations\--much more so than on Earth.

The prolonged MGS aerobraking necessitated by the weakened solar array
damaged during deployment soon after launch has shifted the nominal MGS
mapping mission, so that it now overlaps the MCO mapping mission (see
above). This provides an excellent opportunity for even better
space-time coverage of the atmosphere and surface than could be provided
by either spacecraft alone. Furthermore, it permits intercomparison of
instrument suites to better define instrument and algorithm biases and
errors, permitting observations from different Mars years to be
intercompared quantitatively. Of special interest for instrument
validation are contemporaneous, spatially co-incident (to the extent
possible) observations by the MGS Thermal Emission Spectrometer (TES)
and Radio Science (RS) investigations with the MCO PMIRR and similar
intercomparisons with the MGS MOC and MCO MARCI.

**4.0 SCIENCE INVESTIGATIONS: MARS CLIMATE ORBITER**

**4.1 Pressure Modulator Infrared Radiometer (PMIRR)**

PMIRR is a nine-channel limb and nadir scanning atmospheric sounder
designed to vertically profile atmospheric temperature, dust, water
vapor and condensate clouds and to quantify surface radiative balance.
PMIRR observes in a broadband visible channel, calibrated by
observations of a solar target mounted on the instrument, and in eight
spectral intervals between 6 and 50 µm in the thermal infrared. High
spectral discrimination in the 6.7 µm water vapor band and in two parts
of the 15 µm carbon dioxide bands is achieved by employing pressure
(density) modulation cells in front of selected spectral detectors.
Adequate signal-to-noise in these channels is ensured through the
placement of their detectors on a cold focal plane assembly cooled to 80
K by a passive radiative cooler. The reflight of PMIRR is a joint
enterprise of JPL, Oxford University and of the Russian Space Research
Institute (IKI, as part of the "Mars Together" Program). The PMIRR
Principal Investigator is Dr. Daniel McCleese (JPL/Caltech); Vasily
Moroz (Russia) is Joint Principal Investigator. Table I lists the PMIRR
team members selected by NASA and the supporting team members from IKI.

No PMIRR science observations are taken prior to the MCO achieving its
mapping orbit, when the PMIRR radiator door is fully opened. Once PMIRR
is deployed in the mapping orbit, vertical profiles of atmospheric
properties are constructed from observations in three fields-of-view
(FOV) stepped across the limb and onto the planet using a two-axis scan
mirror in front of the primary telescope. Nominally, PMIRR views the aft
limb, referenced to the spacecraft, except for the polar regions where
it routinely views in and out of the plane of the spacecraft track to
quantify the polar surface albedo by observing much of the bi-direction
reflectance distribution function. PMIRR can also view to the side limb,
acquiring observations characterized by different local times.

PMIRR is essentially a rebuild of the instrument flown on Mars Observer,
with the following significant changes: Deletion of an enriched isotopic
mixture for the pressure modulation cell containing carbon dioxide;
slightly different passbands for the uncooled detectors at wavelengths
longward of the 15-micron carbon dioxide band; deletion of the optical
aperture and solar calibration target covers and associated mechanism;
different drive path for the optical chopper assembly. Science
objectives of the instrument remain unchanged. Details of the Mars
Observer PMIRR can be found in the following references:

McCleese, D. J., R. D. Haskins, J. T. Schofield, R. W. Zurek, C. B.
Leovy, D. A. Paige, and F. W. Taylor, 1992: Atmosphere and Climate
Studies of Mars Using the Mars Observer Pressure Modulator Infrared
Radiometer. *J. Geophys. Res*., *97*,

7735-7757.

McCleese, D. J., et al., 1986: Remote sensing of the atmosphere of Mars
using infrared pressure modulation and filter radiometry. *Appl. Opt*.,
*25*, pp. 4232-4245.

  -----------------------------------------------------------------------
  **Table I**

  ***PMIRR PARTICIPATING SCIENTISTS\****

  M. ALLISON J. BARNES H. HOUBEN

  NASA Goddard Institute for Space Studies Oregon State University NASA
  Ames Research Center

  \*Note: The three participating scientists listed here were selected as
  part of the Mars Observer Mission Participating Scientist Program to be
  associated with the PMIRR investigation. When PMIRR was chosen by NASA
  for reflight on the Mars Climate Orbiter, these three investigators
  were included as members of the PMIRR Science Team.
  -----------------------------------------------------------------------

  -----------------------------------------------------------------------
  **Table I**

  **(continued)**

  ***PMIRR SCIENCE TEAM INVESTIGATORS***

  **US UK RUSSIA**

  **DANIEL J. MCCLEESE** **(PI)** FREDRIC W. TAYLOR V. I. MOROZ (Joint
  PI)

  Jet Propulsion Lab/Caltech Oxford University Space Research Institute

  ROBERT D. HASKINS SIMON B. CALCUTT A. GRIGORIEV

  Jet Propulsion Lab/Caltech Oxford University Space Research Institute

  CONWAY B. LEOVY PETER READ N. IGNATOV

  University of Washington Oxford University Space Research Institute

  DAVID A. PAIGE YU. NIKOLSKY

  University of California, L. A. Space Research Institute

  DAVID M. RIDER D. TITOV

  Jet Propulsion Lab/Caltech Space Research Institute

  JOHN T. SCHOFIELD (Deputy PI) L. ZASOVA

  Jet Propulsion Lab/Caltech Space Research Institute

  RICHARD W. ZUREK

  Jet Propulsion Lab/Caltech
  -----------------------------------------------------------------------

**4.2 Mars Color Imager (MARCI)**

MARCI combines Wide Angle (WA) and Medium Angle (MA) cameras with
individual optics but identical focal plane assemblies, data acquisition
system electronics, and power supplies. Each camera is small in size (≈
6 x 6 x 12 cm, including baffle) and mass (\< 500 gm). Both cameras
operate in a \"pushframe\" mode, with their CCD detectors overlain with
spectral (\"color\") filter strips. The cameras are electronically
shuttered at intervals timed so that the spacecraft motion spatially
overlaps each filter strip view, thereby providing a \"color\"
composite. The MARCI Principal Investigator is Dr. Michael Malin (Malin
Space Science Systems, San Diego). Table II lists the MARCI team members
selected by NASA.

Near the end of the MCO cruise phase, MARCI acquires approach images of
Mars. Once in the mapping orbit, MARCI provides daily global images of
the Mars atmosphere (and surface) with the WA camera and monitors
surface changes with the MA camera during mission periods with high data
rates.

The WA camera has five spectral bands (including 250 and 330 nm, in
addition to three conventional color settings) and has spatial
resolutions on the planet better than 7.2 km/pixel, for nominal orbital
altitude and downlink data rates. Kilometer-scale resolutions are
possible, when data rates permit. Limb observations detail the
atmospheric structure of clouds and hazes at ≈ 4 km resolution. The MA
camera has a 6˚ FOV covering 40 km at 40 m/pixel (nadir) and accessing
all positions of the planet (except the rotational poles due to the
slight inclination of the spacecraft orbit). Ten spectral channels from
425 to 1000 nm provide the ability to discriminate both atmospheric and
surface features on the basis of composition.

  ----------------------------------------------- -----------------------
  **Table II**                                    

                                                  

  ***MARCI and MARDI SCIENCE TEAMS***             

                                                  

  **MICHAEL C. MALIN (PI)**                       

  Malin Space Science Systems, San Diego, CA      

                                                  

                                                  

  ***MARCI***                                     ***MARDI***

                                                  

  JAMES F. BELL III R. TODD CLANCY                MICHAEL H. CARR

  Cornell University Space Science Institute      U. S. Geological Survey

  Boulder, CO                                     Menlo Park, CA

  WENDY M. CALVIN                                 

  U.S. Geological Survey ROBERT M. HABERLE        STEVEN SQUYRES

  Flagstaff, AZ NASA Ames Research Center         PETER THOMAS

                                                  JOSEPH VEVERKA

  PHILIP B. JAMES                                 Cornell University

  University of Toledo STEVEN W. LEE              

  Laboratory for Atmospheric                      

  PETER THOMAS and Space Physics                  

  Cornell University University of Colorado       
  ----------------------------------------------- -----------------------

**5.0 SCIENCE INVESTIGATIONS: MARS POLAR LANDER**

**5.1 Mars Descent Imager (MARDI)**

MARDI includes a single camera head consisting of optics, focal plane
assembly and support electronics, and housing. Using a megapixel,
electronically shuttered CCD, MARDI provides panchromatic images of the
landing site with a resolution of 1.25 mrad/pixel. Images are taken
following jettison of the aeroshell and parachute deployment until
landing. Under nominal circumstances the equivalent of ten 1000 x 1000
pixel images will be acquired. Taken at altitudes less than 8 km above
the surface, these images cover areas from 9 km to 9 m across and at
resolutions of 7.5 m to 9 mm per pixel pair. MARDI is built by Malin
Space Science Systems (MSSS), with Dr. Michael Malin (MSSS) as Principal
Investigator. Table II lists the MARDI team members selected by NASA.

**5.2 Mars Volatiles and Climate Surveyor (MVACS)**

The MVACS is an integrated payload of five major science elements: a
Surface Stereo Imager, a Robotic Arm with Camera, a Meteorological
package of pressure, temperature, wind, and water vapor sensors, a
Surface Thermal Probe, and a Thermal and Evolved Gas Analyzer. Dr. David
Paige (UCLA) is the Principal Investigator for the MVACS. Table III
lists the MVACS team members selected by NASA.

Because MVACS is an integrated payload, the MVACS team has the
responsibility for producing an integrated sequence commanding all of
the MVACS science elements. This sequencing activity, data review, and
initial data analysis will be carried out during the MPL landed mission
primarily at a facility in the Science and Technology Research Building
at UCLA. MVACS data packets will be pulled from the MSOP data base by
the Multi-Mission Imaging Process Laboratory (MIPL) at JPL, will be
stripped of spacecraft headers and will have ancillary data appended.
Imaging data will be decompressed and the raw images sent, along with
other types of instrument data, to the UCLA data base via the MSOP
supplied Science Operations and Planning Computer (SOPC).
Representatives from the LIDAR team will also be present at UCLA to
generate coordinated observational sequences for the entire payload (see
below).

**5.2.1 Surface Stereo Imager (SSI)**

The mast-mounted SSI provides panoramas of the MPL site, characterizes
the general environment at the landing site, and provides imaging
support for other payload elements, especially operations of the RA and
TEGA, and for the spacecraft, as needed. The SSI is essentially a clone
of the Mars Pathfinder IMP; it is a multi-spectral stereo imager
accessing several wavelengths between 0.4 and 1.1 microns (same as IMP).
This multi-spectral capability, together with onboard calibration
targets, provides true color images. SSI also images magnetic targets on
the Lander deck to characterize the magnetic properties of surface
material. Narrow-band imaging of the sun provides line-of-sight optical
depths of atmospheric aerosols and (slant column) water vapor
abundances. Stereo imaging is provided by the dual optical lens systems
focusing onto a single CCD. Drs. Peter Smith and Uwe Keller have lead
responsibility for the SSI and RAC. Magnetic targets to be viewed by the
SSI and RAC, as a test of soil and atmospheric dust properties, were
supplied by researchers at Copenhagen University, Denmark.

**5.2.2 Robotic Arm (RA); Robotic Arm Camera (RAC), Surface Thermal
Probe (STP)**

A two-meter RA with an articulated end effector is used to dig trenches
at the site, to acquire samples of surface and subsurface materials, and
to support operations of an attached RA Camera. The RAC will image the
surface and subsurface at close range to reveal fine-scale layering if
present and to characterize the fine-scale texture of the samples and
trench sides. Mechanical (joint) positions and motor currents for the RA
will be downlinked to permit study of soil mechanical properties; the RA
will also conduct simple experiments with the soil to better understand
these soil properties. The light-weight RA also supports the STP, which
is inserted into the soil to measure near-surface temperatures
passively, but which can also generate a heat pulse whose decay can be
monitored, as another means of defining the ground heat capacity.

**5.2.3 Meteorological Package (MET)**

Mounted on a 1.2-m mast, the MET package includes a wind (speed and
direction) sensor, several temperature sensors, and Tunable Diode Lasers
(TDL) which measure water vapor amounts and perhaps some carbon dioxide
isotope ratios, depending upon final performance and temperature control
in the Mars environment. A secondary mast (0.9 m in length) is attached
to the main MET mast, and supports a wind speed and two temperature
sensors near the surface saltation layer. Pressure sensors are mounted
within the spacecraft. During descent of the Lander to the surface, the
MET sensors are read following parachute deployment and aeroshell
release. Once on the surface the MET sensors are read at periodic
intervals, as power permits. Dr. David Crisp has lead responsibility for
the MET instruments, and Dr. Randy May for analysis of the TDL data. Dr.
Laurie Leschin has lead responsibility for interpretation of the TDL
isotopic measurements.

**5.2.4 Thermal and Evolved Gas Analyzer (TEGA)**

TEGA uses differential scanning calorimetry (DSC) combined with
gas-specific sensors to determine the concentrations of ices, adsorbed
volatiles and volatile-bearing minerals in surface and subsurface
samples acquired and imaged by the Robotic Arm (RA). The RA deposits the
sample on a grated screen over a chute which fills the sample
receptacle. This receptacle is then mated with a cover to form the oven
in which the sample is heated; a paired (empty) oven provides a
calibration for the heating run. Evolved gases are flowed by a supply of
nitrogen (N2) purge gas to sensors which quantify the rate of discharge
of oxygen, carbon dioxide and water vapor. Once used, the ovens cannot
be used again. TEGA is designed to analyze eight surface (soil) samples
during the Lander mission. Dr. William Boynton has the lead
responsibility for the TEGA investigation.

  ----------------------------------- -----------------------------------
  **Table III**                       

                                      

  ***MVACS SCIENCE TEAM               
  INVESTIGATORS***                    

                                      

  **DAVID A. PAIGE (PI)**             

  University of California            

  Los Angeles, CA                     

                                      

  CANDICE J. HANSEN (Deputy PI)       

  Jet Propulsion Laboratory, Caltech  

  WILLIAM V. BOYNTON                  DAVID CRISP

  Lunar and Planetary Laboratory      Jet Propulsion Laboratory

  University of Arizona               California Institute of Technology

                                      

  PETER H. SMITH                      RANDY D. MAY

  Lunar and Planetary Laboratory      Jet Propulsion Laboratory

  University of Arizona               California Institute of Technology

                                      

  H. UWE KELLER                       LAURIE A. LESHIN

  Max-Planck-Institute for Aeronomy   Department of Geology

  Germany                             Arizona State University

                                      

  ARI-MATTI HARRI                     RICHARD W. ZUREK

  Finnish Meteorological Institute    Jet Propulsion Laboratory

  Finland                             California Institute of Technology

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

**5.2.5 Potential Areas of Emphasis for Participating Scientists with
MVACS**

The following areas were identified in the original MVACS proposal for
consideration for those proposing as Participating Scientists:

-   Soil Mechanical Properties: Participate in planning of RA soil and
    mechanics experiments and analysis of Robotic Arm joint positions
    and motor current data.

-   SSI Spectoscopy and Photometry: Participate in the planning and
    analysis of Surface Stereo Imager spectroscopic and photometric
    observations to better constrain the physical properties and
    mineralogy of the surface materials at the landing site.

**5.3 LIDAR**

The LIDAR is an upward viewing lidar mounted on the Lander deck. It
consists of a sensor assembly, an electronics assembly, and the
interconnecting cable assembly. The LIDAR is provided by Dr. V. S.
Linkin, Principal Investigator, and colleagues of the Space Research
Institute (IKI) of the Russian Academy of Science, under the sponsorship
of the Russian Space Agency (RSA). Proposals for an American
investigator to work with the LIDAR team in the acquisition and analysis
of LIDAR data may be submitted under this AO.

The LIDAR transmitter uses a pulsed GaAlAs laser diode which emits 400
nJ energy in 100 nsec pulses at a rate of 2.5 kHz and at 0.88 µm
wavelength. The LIDAR has two sounding modes. During active sounding,
light pulses are emitted and their return timed in order to locate and
characterize ice and dust hazes in the lowest few kilometers (\< 2-3 km)
of the atmosphere. During passive sounding, sunlight at 0.88 µm is
detected and used to characterize optical properties of atmospheric
particulates.

The LIDAR electronics assembly, situated on the Lander deck, will also
house a microphone built by U. S. Collaborators to explore the acoustic
environment at the MS'98 Lander site. Scientific analysis will include
correlation of acoustic events with MVACS measurements of wind and
imaging of movement of surface material.

During MPL surface operations, the LIDAR team will have personnel at the
UCLA MVACS team operations center at UCLA. There, they will receive data
via the MVACS SOPC link to the JPL project data base, and they will work
together with the MVACS team to produce coordinated sequences for MPL
science observations, which will be transmitted back through JPL and on
to LMA, for transmission to the MPL.

**6.0 GENERAL INFORMATION**

General information about the Mars Surveyor '98 Mission can be found by
returning to the Mars '98 Home Page. More information about the
MARCI/MARDI and MVACS investigations can be found by clinking on the
Related Links of the Mars '98 Home Page (mars.jpl.nasa.gov/msp98).

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