Minutes from Mars Landing Site Steering Committee Meeting

Held March 13th, 2001, at Tommy's Patio Restaurant in Houston, TX

Meeting began with business items at \~12:00 p.m. and was followed by
lunch before being closed at \~1:15 p.m.

The following members of Steering Committee were in attendance: John
Grant, Matt Golombek, Ken Tanaka, Dick Morris, Roger Phillips, George
McGill, Mike Shepard, Tim Parker Also in attendance were Jim Garvin
(NASA Mars Program Scientist), Cathy Weitz (NASA MER Program Scientist),
and Trent Hare (USGS landing site web site manager). Input on relevant
issues discussed was solicited prior to the meeting via e-mail from
Steering Committee members not able to be in attendance.

Discussion opened with a review of the upcoming schedule for Mars
Landing Site Selection activities. Updates on activities were presented
at the recent 32^nd^ LPSC with an additional update to be given at the
Geologic Mappers Meeting in Albuquerque in June 2001. A Steering
Committee meeting is planned for Fall 2001 (Date TBD, likely to coincide
with Athena Team Meting at Cornell) to review newly obtained MOC images
and other supporting data for high priority landing sites. As outlined
in the minutes from the 1/25/01 Steering Committee meeting, the Fall
2001 meeting will be a "hybrid" Steering Committee meeting with the
community being represented largely by persons assigned to particular
high priority sites identified at the Ames workshop. Additional
web-based comment mechanisms will be established to enable members of
the science community to post additional information related to review
of the high priority sites. It was agreed that assigning one person to
take the lead in evaluating the science potential of a particular site
(e.g., the person proposing the site at the Ames meeting) was a good
idea. This person would be encouraged to review the landing site in
context of all supporting data and to coordinate with other interested
persons who could assist in, or make alternate, presentations. The goal
will be to reprioritize the high and medium priority sites on the basis
of review of all supporting data (not just MOC) to evaluate whether
surface properties and/or science potential warrant a site's relative
priority on the list. It was agreed that the fall 2001 Meeting should be
followed by a second open workshop in the April/May 2002 time frame for
the purpose of recommending the two MER 10° by 15° landing site regions.
A third, open workshop is tentatively planned for Spring 2003 to narrow
the selection to one or two sites (primary and potential back up) within
each landing region.

At present, NASA Headquarters anticipates two reviews of the MER site
selection process/outcomes. The first would follow the down selection to
the two landing site regions or "boxes" in Spring, 2002. The second
would follow the identification of primary and possible back up sites
within each landing site "box" and would take place in Spring, 2003.

The bulk of the meeting was spent discussing the three agenda items
distributed/described in the memo of 2/22/01 (attached below).

The first item in the 2/22 memo related to the difficulty of completing
thermal modeling and testing of the spacecraft in the extremely low
temperatures likely to characterize the low thermal inertia, high albedo
sites. Moreover, it was noted that even if a test program for the
spacecraft could be devised, there would be a significant impact to the
science that could be accomplished at such cold temperature locations.
As a result, the Project has asked the Steering Committee to endorse
elimination of landing sites possessing thermal inertias \<250 SI units
with albedos \>0.26 and \<200 SI units with albedos \>0.18, which yield
atmospheric temperatures colder than -95C. The only high priority site
this would affect is the Elysium Marte Vallis outflow site (EP49B).
Additional nadir only sites of opportunity that would be eliminated from
consideration are Apollinaris at roughly 9.5S, 190.2W, Durius Valles
(EP56A), and the other Elysium site (EP74A). Folowing some limited
discussion (which included the possible substitution of other Elysium
sites for Marte Vallis -- rejected for lack of evidence for flowing
water), the Steering Committee unanimously supported this action.

The second item in the 2/22 memo focused on the targeting of high
priority sites in the Hematite and Isidis regions by MOC during ROTOs.
Because only one site can be targeted during any given orbit, decisions
must be made regarding which ellipse to target first with MOC (e.g., in
the Hematite Region there 5 ellipses were listed as high priority for
either MER A or B). If one of the landers is sent to a high priority
site in Valles Marineris or a crater lake, for example, then MER B would
most likely be sent to Hematite due to the limited range of latitudes
accessible by the two landers. As a result, MER B sites in the Hematite
Region probably should be prioritized higher than MER A sites. Given
this and the preference expressed at the Ames landing site workshop, the
following prioritized list (from highest to lowest) was discussed and
unanimously approved for the Hematite sites.

TM20B, TM21B, TM19B, TM10A, TM9A

Based on similar arguments for Isidis Planitia, the following was
discussed and unanimously approved as the prioritized list for MOC
targeting (from highest to lowest):

IP85A, IP98B

It was stressed during the meeting that the above serves only to
prioritize the sites in these two regions for MOC targeting. This
process should not be interpreted as eliminating the "lowered" priority
Hematite and Isidis sites from consideration.

The third item in the 2/22 memo related to a proposal to slightly shift
the high priority landing ellipses within Melas (to the west) and Gusev
(to the east). This shift has been proposed on the basis of preliminary
analysis of available MOC imagery which indicates: 1) the presence of
extensive dunes, a high scarp, and high regional slope towards the
eastern portion of the layered terrains in Melas; and 2) a relatively
flat and featureless plain in the western portion of Gusev that
transitions to a more deflated, but still relatively smooth surface to
the east (and potential better suited for sampling). Composite images of
the new, slightly shifted sites were reviewed and the Steering
Committtee unanimously approved the proposal.

Other discussion focused on potential issues that may arise in the
future. The first of these relates to potential problems fitting the MER
landing ellipse within Gale crater. Although all agree that this is a
very intriguing and high priority site, a portion of the current ellipse
(approximately 20%) is above the landing elevation limits and includes
sections of 1km+ high crater walls. It was also noted that TES and IRTM
data for the Gale crater site suggests a less rocky surface, otherwise
broadly similar to that at Pathfinder (i.e., moderate dust).

It was pointed out that while the selection of the two MER
latitude/longitude landing "boxes" must be picked by Spring, 2002, the
consideration of all locations within those boxes as final sites can
continue until shortly before launch. It was noted that there may be a
desire to add potential landing ellipses within the "boxes" after Spring
2002 and that it will be important to coordinate image coverage of the
"boxes" with Phil Christensen, PI of THEMIS.

Next, Mike Shepard provided a summary of the work he is doing with Ray
Arvidson and Frank Seelos on processing the MOLA pulse width information
to identify surface properties of the high priority landing ellipses.
They are interested in understanding how the Martian topography behaves
relative to comparison to terrestrial surfaces (based on comparison with
an extensive existing data base). To do this, work focuses on
synthesizing fractal surfaces to see what landing site hazards may look
like based upon the pulse width data. Histograms of pulse width
frequency are being compared with predictions of relief from terrestrial
analog surfaces. For the Hematite sites, TM21B is different from other
sites (smoother at \~150 m scale, but rougher at lander scale hazards).
With this exception, the other Hematite sites are all quite similar.
Crater Gale is the smoothest of the sites examined to date and is
similar to the Hematite sites. Gusev looks to be quite rough, whereas
Melas looks suitable for landing. Mike stressed that the results are
preliminary and it was noted that it might be useful to use the
detrended MOLA data for the work.

Finally, Trent Hare demonstrated the MER 2003 GIS CD to the committee.
Much of the CDs functionality currently exists on the AMES and USGS web
sites, but the inclusion of the stand-alone GIS software, ArcView Data
Publisher, gives the user access to high-level queries, fast data
access, the ability to include their own data sets, customized printing,
and figure generation (exported as image or postscript). The CD contains
many global data sets but also targets the high priority landing site
areas with several more detailed data sets. Example databases include;
MDIM1, MDIM2 (local), MOLA Shaded relief (global and local), surface
roughness, elevation and slope contours, Viking IRTM, MOC footprints,
MOC narrow angle images (local), TES derived data sets, etc. An Ellipse
generator has been added to the software and will allow the users to
create a correctly sized and rotated error ellipse. The ellipse will
also generate information for several layers and a one-page map report.
To help ArcView and GIS novices, the CD also comes with an \"Intro to
ArcView GIS\" help section. Software patches and new/updated data sets
will be at http://webgis.wr.usgs.gov/mer. More statistical information
can be added to the ellipse report when the original data sets can be
acquired (not just images of the data sets).

## February 22, 2001

**To: Landing Site Steering Committee**

**From: M. Golombek and J. Grant**

# Re: Update on Thermal Constraints and ROTO Targeting

The following is an update on two issues that have surfaced related to
landing site selection that we would like to make you aware of and
receive any comments you might have. In order to ensure the opportunity
to incorporate your input and discuss any other issues that may arise,
we have scheduled a Steering Committee Meeting during the upcoming LPSC
in Houston. Plans are to convene over lunch on Tuesday, 3/13, at a venue
to be determined (but that will be close to the meeting).

**[Cold Temperature Sites:]{.underline}**

As was noted and discussed during the Ames landing site workshop,
thermal modeling of the spacecraft has shown extreme difficulty in
testing the spacecraft in the extremely low temperatures likely at low
thermal inertia, high albedo sites. Simple atmospheric thermal modeling
shows that sites with thermal inertias \<250 SI units with albedos
\>0.26 and \<200 SI units with albedos \>0.18, yield atmospheric
temperatures colder than -95C. The current thermal design is based on a
minimum atmospheric temperature of -95C, which thermal modeling shows
that certain external hardware is about 10C colder (105C). For the
required 15C test margin, this requires thermal qualification testing to
-120C, which is the limit of present test facilities. Testing at
temperatures colder than this would likely impact the cost, schedule and
success of the test program.

Even if a test program could be devised, there would be a significant
impact to the science that could be accomplished at cold temperature
locations. Thermal modeling shows that about 56 W-hr is required to keep
the rover interior warm at these locations, which translates into about
4 hours less instrument usage or 0.5 hours less data downlink per Sol.
In addition, for external equipment, heaters would have to be added that
would require an additional 20 W-hr (as well as mass and complexity),
for these colder sites. Sites that have low thermal inertia and high
albedo are generally considered to be dusty. Excess dust could further
reduce solar power and coat rocks and surface materials. If surfaces at
the site are coated with dust, it will be much harder to distinguish
different materials with the Mini-TES, thereby reducing the variety of
materials that can be measured in situ with the APXS and Mossbauer
spectrometer and reducing the potential science return at these sites.
As a result, the project is unanimous in requesting and endorsing this
change.

The impact on the landing sites under consideration is as follows. Of
the highest priority sites identified at the landing site workshop, only
the Elysium Marte Vallis outflow site (EP49B) would be eliminated.
Additional nadir only sites of opportunity that would be eliminated are
Apollinaris at roughly 9.5S, 190.2W, Durius Valles (EP56A), and the
other Elysium site (EP74A). None of the other high priority or targets
of opportunity sites would be affected.

**[ROTO Imaging:]{.underline}**

Images released by MOC of the landing sites in the past month are
considerable (about 60). Many of the landing site ellipses are already
covered by multiple MOC image swaths and we can look forward to ongoing
excellent MOC coverage of the landing sites. These images have been
released to the community and are available at the USGS and Ames web
sites.

Preliminary review of these images permits identification of potential
landing hazards and interesting science targets and has warranted a
slight shift in two of the high priority landing ellipses. In Gusev
Crater, the ellipse has been shifted slightly to the east, whereas in
Melas Chasma, the ellipse has been moved slightly to the west. The new
ellipse centers are located at approximately 184.15W, 14.85S and 77.78W,
8.80S for the Gusev and Melas sites, resepectively (see attached
images).

There are two high priority landing regions, however, where many
ellipses are bunched together (Hematite and Isidis), and decisions must
be made regarding which ellipse to target with MOC in any given orbit as
only one can be imaged during any given ROTO. Hence, it is necessary to
prioritize targets within these two areas.

For the Hematite Region there are 5 ellipses (see attached image). If
one of the landers is sent to a high priority site in Valles Marineris
or a crater lake, for example, then MER B would most likely be sent to
Hematite due to the limited range of latitudes accessible by the two
landers. As a result, MER B sites in the Hematite Region probably should
be prioritized higher than MER A sites. Given this and the preference
expressed at the Ames landing site workshop, the following prioritized
list (from highest to lowest) is suggested for the Hematite sites.

TM20B, TM21B, TM19B, TM10A, TM9A

Based on similar arguments for Isidis Planitia (see attached image), the
following is a suggested prioritized list (from highest to lowest):

IP85A, IP98B

**[Summary Request:]{.underline}**

Because of the potential impact to the MER Project (due to the thermal
issue) and MOC imaging of the landing sites (due to the need to target
during ROTOs), we request your review and comment on these issues ASAP.
Please review these requests and attached materials at your earliest
convenience and provide any feedback via e-mail to both John and Matt.
We will discuss these items further during the lunch meeting at LPSC.