Dear Colleague:

As a participant in a previous workshop for selecting landing sites for the 2003 Mars Exploration Rovers, you are invited to participate in the "next step" of the landing site selection process at the 3^rd open workshop in Pasadena, CA, from March 26-28^th, 2002.

The process of selecting landing sites for the twin MER rovers began in late 2000 with over 185 potential sites under consideration. The science community initially prioritized these sites on the basis of presentations made at the first landing site workshop at NASA Ames in January 2001. Of the 26 sites emerging from the Ames workshop and recommended for further consideration, 17 sites (21 ellipses) were identified as moderately high priority and recommended for MOC imaging during nadir opportunities. 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).

Subsequent evaluation of Mars Global Surveyor (MGS) data and refinement of engineering safety constraints resulted in elimination of one ROTO site (Elysium) and 4 seven slightly lesser priority ellipses. By contrast, analysis of smaller landing ellipses enabled by a combination of simultaneous spacecraft tracking by two Deep Space Network stations and a 5^th trajectory correction maneuver 48 hours before entering Mars’ atmosphere ultimately led to inclusion of six additional potential landing sites. One of the six sites added was the Athabasca Vallis site, to the north of the original high priority Elysium site.

A second workshop was held in Pasadena, CA, in October 2001 and resulted in a further narrowing of the field to include four primary landing sites (Hematite, Melas Chasma, Gusev Crater, and Athabasca) with two backup sites (Isidis and Eos Chasma). Subsequent evaluations of radar data for the sites and associated concerns related to landing safety and rover trafficability resulted in demotion of the Athabasca site to backup status, whereas the Isidis site was elevated to one of the four primary sites.

These remaining sites are being targeted for high-resolution imaging by MGS and Mars Odyssey and each of the four primary sites is in the process of a detailed evaluation by the MER project that will culminate in discussions with that will include input fromthe science community at a the 3^rd open workshop in March 2002. Final selection and NASA approval of two landing regions (10° X 15°) will occur in Spring 2002, with final selection of specific ellipses within these regions by May 2003. Concerns over the thermal environment at some sites as well as small changes in ellipse size afforded by adoption of a 5^th.

In addition to community input to the landing site selection process, all outcomes are approved evaluated by and a NASA-appointed Steering Committee and NASA Headquarters. Additional details related to each step of the MER landing site selection process and supporting data sets (including MOC images) are posted regularly at both the Ames and USGS websites and community review and comment is encouraged (see http://marsoweb.nas.nasa.gov/landingsites/mer2003 and http://webgis.wr.usgs.gov/mer).

The next stage of the process will involve a comprehensive discussion of the sites remaining under consideration in order to provide community input regarding which two are best suited to achieving mission science objectives within the limitations imposed by satisfying landing and rover safety requirements. The mission requirement of down-selecting to two broad landing regions (10° X 15°) by early Spring 2002 necessitates that this discussion take place at a 3^rd open workshop in Pasadena, CA, from March 26-28^th, 2002.

The 3^rd landing site workshop will focus only on discussion of the landing sites remaining under consideration and will emphasize those four deemed of highest priority and potential based on science and landing/roving safety considerations.

NASA Headquarters has endorsed this plan and has asked the Landing Site Steering Committee to enlist community input and lead the process of providing this input to the Project and Athena Science Team for their considieration. To accomplish this, the March meeting in Pasadena 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., and representatives from NASA Headquarters.

The goal of the third workshop is to make recommendations concerning which two landing sites/regions are the highest priority based on consideration of all information that is available regarding their science potential and safety. It is expected that discussion will revolve around presentations made by the Project, Athena Science Team personnel, and the broader Mars science community. Hence, presentations on surface characteristics and safety considerations as well as MER mission relevant science that can be accomplished within the landing ellipses are welcome. Anyone who feels that they have results and/or data relevant to the safety and/or science potential of the sites is invited to request a presentation at the workshop.

The workshop format will include oral presentations and ample time for discussion. Unlike the second workshop, a single science spokesperson will not be asked to represent each site. Rather, we anticipate the workshop being divided into sessions on the basis of the number and breadth of potential topics.

We ask that you e-mail John Grant ( (grantj@nasm.si.edu) and Matt Golombek (mgolombek@jpl.nasa.gov) by COB February 6, 2002, if you are interested in making a presentation at the workshop. Your request should include a title, list of authors and speaker, as well as a brief (limited to 250 characters) description of the talk. We anticipate that speakers will be notified of the status of their requested presentation via release of a preliminary program in early March, 2002. It is expected that all speakers will provide an electronic version of their presentation materials for posting on the landing site websites.

All members of the science community are invited to attend and participate in the 3^rd landing site workshop. The workshop will be held at the Embassy Suites in Pasadena-Arcadia with additional logistical information to follow. Unfortunately, it will not be possible to reimburse travel expenses related to the meeting.

Following the 3^rd workshop, the Project and Athena science team will review all contributions to the landing site selection process and submit two landing site regions to NASA Headquarters for approval. Once approved, consideration of specific ellipses within the two 10° X 15° landing regions will continue and culminate in a 4^th workshop to be held in early 2003. In addition, it is expected that the process of identifying possible landing sites for the Mars 2009 Smart Lander mission will begin in either 2003 or 2004. Presentations related to both of these future activities will be solicited from the science community as well as individuals involved in Mars mission planning and surface characterization studies.

We recognize that your input is critical to the success of the landing site selection process and hope that you will participate in all of these activities.

Sincerely,

John Grant and Matt Golombek

Co-Chairs, Mars Landing Site Steering Committee