Dear Colleague:

As a participant at the Mars landing site Workshop held at NASA Ames this
past January, your participation in the “next step” of the landing site
selection process is solicited.

An Overview of the Process to Date –

As you are aware, the process of selecting landing sites for the twin MER
rovers began with over 185 potential sites under consideration. The science
community initially prioritized these sites on the basis of presentations
made at the Ames workshop: 26 sites were recommended for further
consideration based on preliminary assessment of science potential and
landing safety sites (33 ellipses when counting some overlapping sites
potentially accessible by either MER A or B).

Of the 26 sites emerging from the Ames workshop, 17 sites (21 ellipses)
were identified as moderately high priority and recommended for MOC imaging
during nadir opportunities (hereafter referred to as Nadir Sites). An
additional 9 sites (12 ellipses) were identified as highest priority and
recommended for MOC imaging via ROTO observations (hereafter referred to as
ROTO sites). MOC images obtained of all of these sites are posted regularly
at both the Ames and USGS websites and community review and comment is

Evaluation of MOC images and other data has identified features in a few of
the sites (e.g., landing/egress hazards or that might compromise science
potential) that resulted in proposals to either shift some landing site
ellipses slightly or to no longer consider a few sites as viable. Each of
these proposals was reviewed and discussed by the NASA-appointed Landing
Site Steering Committee. Based on unanimous opinion and NASA concurrence,
the location of two ROTO ellipses (Melas Chasma and Gusev Crater) has been
slightly shifted and one ROTO site (in Elysium) and 7 Nadir ellipses have
been eliminated from consideration. Elimination of these sites was based on
expected cold temperatures inferred from albedo and thermal inertia data
(see Ames and USGS landing site websites) or hazardous surface relief and

The Next Step –

The next stage of the process will involve a comprehensive evaluation of
the highest priority sites remaining under consideration in order to arrive
at consensus regarding their relative priority. More specifically, the
mission requirement of down-selecting to two broad landing regions (10 X 15
degrees) by early Spring 2002 necessitates discussion of which remaining
sites are of the highest priority, whether some sites should no longer be
considered, or if others should be elevated in priority. Your input will
comprise a critical element of these discussions.

Evaluation and “reprioritization” of the sites will take place at Cornell
University, in Ithaca, NY, from September 17-18th, 2001. Because of the
focus being placed on consideration of sites already assessed as high
priority by the science community, the format of this meeting will only
include presentations related to characterization and science potential of
those sites. Presentations on alternate or new sites will not be possible
during this meeting. A major outcome of the meeting will be a shortened
list of sites (four) which can be recommended to the JPL project, science
team, and NASA Headquarters for detailed evaluation in time for selection
of the two landing regions at a workshop in March of 2002.

In addition to the four primary sites, we will maintain a limited number of
sites as backups in the event that any safety or science problems are
identified with the primary sites.

NASA Headquarters has endorsed this plan and has asked the Landing Site
Steering Committee to enlist community input and lead the process of
recommending the highest priority sites. To accomplish this, the September
meeting at Cornell will include the Landing Sites Steering Committee,
members of the science community, key MER project/science team personnel,
and members of the Athena science team. The landing site meeting will
immediately precede an Athena Science Team Meeting.

An Invitation to Participate –

The format for science community input will include oral presentations by a
representative for each of the highest priority ROTO sites emerging from
the Ames workshop in January (e.g., Hematite site, Gusev Crater, Gale
Crater, Valles Marineris, Melas Chasma, and southern Isidis Basin). The
science spokesperson for each of the highest priority sites will be asked
to present a summary of the science potential of the site (relative to the
MER mission science objectives) at the September meeting in Ithaca.

We encourage input from the broader science community regarding the
relative merits of the sites (via website and e-mail submission of
comments) and will forward relevant materials to the spokesperson for each
site. Members of the science community are welcome to attend and
participate in the September meeting discussions at Cornell. Presentations,
however, will be limited as noted above. It will not be possible to
reimburse you for travel expenses related to the meeting.

In addition to presentations by members of the community on the science
potential of the sites, persons involved in Mars characterization studies
are also being invited to attend. These studies will relate to the surface
characteristics and safety of the sites under consideration. Presentations
on surface characteristics and safety considerations do not need to be
coordinated with the presentation by the “landing site spokesperson”. The
combination of science input and results of characterization efforts will
provide the basis for arriving at consensus on which four sites should
remain under consideration for detailed study for the 2003 MER rovers and
which sites should be maintained as backups.

Future Activities –

The next step in the process will take place during an open landing site
workshop to be held in March or April, 2002, and will focus on two
activities. The first involves down selection of the two landing regions
(10° by 15° landing regions) for the 2003 Mars Exploration Rovers and
continued scrutiny of specific landing ellipses within these regions. The
second activity will begin the process of identifying possible landing
sites for the Mars 2007 mission. Presentations related to both of these
activities will be solicited in a future announcement from the science
community as well as individuals involved in Mars mission planning and
surface characterization studies. We hope that you will plan to attend and
participate in this meeting as well.

We recognize that your input is critical to the success of the landing site
selection process. Hence, we ask that you e-mail John Grant
( and Matt Golombek ( September
1st, 2001, regarding input to the relative science merits of the high
priority landing sites and whether you will attend the meeting in Ithaca.


John Grant and Matt Golombek

Co-Chairs, Mars Landing Site Steering Committee

John Grant

Center for Earth and Planetary Studies

National Air and Space Museum

Smithsonian Institution

4th and Independence SW

Washington, DC 20560-0315

202-357-1494 (Voice)

202-786-2566 (Fax)