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Mars Exploration Rover Project

September 11, 2000 
From: M. Golombek, Mars Exploration Program Landing Site Scientist

Mars Exploration Rover Landing Site Selection Plan

This memo is a draft of a plan for selecting landing sites for the Mars Exploration Rovers (MER) being readied for launch in '03.The purpose is to agree on a schedule and working structure for these selections that is compatible with the Project, the Mars Exploration Program, and NASA Headquarters, and that provides input opportunities for the Mars science community in general and the Mars Data Analysis Program Characterization investigators in particular.

Site Selection Process Summary

Selection of a landing site involves identifying engineering constraints, such as elevation and latitude, that result from the lander design and the entry, descent and landing scenario of the spacecraft. These constraints change as the mission design evolves due to engineering trade studies and test results on spacecraft hardware are completed. In addition, environmental conditions on Mars (e.g., slopes, rock abundance, etc.) must be defined for the spacecraft engineers to allow a design that satisfies the mission and science requirements. The engineering constraints must also be mapped into specific remote sensing criteria that define safe landing sites on Mars and these sites must be evaluated in detail during the down selection process.These two activities must be integrated so that the best scientific data is used to define the types of sites that can be accommodated by the lander and to allow selection of a landing site that is both safe and scientifically interesting. This is an interactive and changing process that requires close coordination between the mission engineers and scientists knowledgeable about the surface characteristics of Mars and capable of translating these constraints into engineering requirements and assessing the hazards due to these parameters.This process was employed successfully in selecting a safe and scientifically interesting landing site for the Mars Pathfinder mission [e.g., M. P. Golombek et al., 1997, JGR, v. 102, p. 3967-3988.]. It was done in an open environment and provided multiple opportunities for community involvement as well as public outreach and education activities.

Site Selection Activity Summary

Obtaining program level and Mars science community input to the landing site selection process as it evolves has been formalized through the appointment (by the JPL Mars Exploration Program Office and NASA Headquarters, respectively) of a JPL Mars Exploration Program (MEP) Landing Site Scientist (M. Golombek) and an external Landing Site Coordinator (J. Grant, SUNY College at Buffalo). The MEP Landing Site Scientist coordinates landing site activities between the projects and helps the MER Project define the engineering constraints, identify and evaluate potential landing sites via remote sensing data, and conduct the down selection process. The Landing Site Coordinator convenes open landing site workshops, communicates with NASA Headquarters, and coordinates external landing site activities (including the Mars Data Analysis Program Characterization investigators).M. Golombek and J. Grant chair a NASA appointed Landing Site Steering Committee that provides external Mars science community guidance and feedback on the down selection activity.

Site Selection Schedule

A schedule for landing site selection activities has been proposed from preliminary discussions with the MER Project, the Landing Site Coordinator, and NASA Headquarters.Preliminary engineering constraints have been defined, preliminary remote sensing criteria for safe landing sites have been defined, and a number of potential landing sites have been preliminarily identified based on these criteria. We would provide the basic engineering constraints and remote sensing criteria to the science community in our call for a first landing site workshop tentatively scheduled for Jan. 2001 at the Lunar and Planetary Institute in Houston, TX.The call would request abstracts and presentations on any aspect of landing site selection relevant for MER and future Mars Surveyor missions. Topics would include general scientific and safety considerations as well as proposals for specific landing sites. Following this meeting and input from the Landing Site Steering Committee and the PSG, a prioritized list of prospective landing sites would be constructed for targeting by the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) and other instruments. For reference, the MGS extended mission plan that begins in February 2001 has roughly one third of all MOC images, which includes roughly 2 targeted images per day, available for landing site evaluation.Detailed landing site evaluations will be performed with these new data and existing data by the project, the MEP Landing Site Scientist, the MDAP Characterization investigators, and the broad Mars science community.

Following the acquisition of new MOC images and landing site evaluations, the Project and the Landing Site Steering Committee would reprioritize the top sites for each rover sometime between June and October 2001.We have not decided if another full up workshop would be required at this point or whether community input could be garnered via e-mail and posting of images and analyses on the web, and presentations at other workshops and meetings in that time frame. (This decision can be made after the first workshop, when we have a better idea of the total number of sites possible.)In either case, the sites would undergo further scrutiny and additional new MOC images would be acquired throughout 2001 and early 2002.Another open landing site workshop would be scheduled in April 2002 that focused in detail on the highest priority sites.Acquisition of new MOC images would continue and THEMIS data would be acquired beginning in 1/02.The project would select the landing site after the April 2002 workshop with input from the Landing Site Steering Committee and the science community. NASA Headquarters would review and approve the sites in May 2002 and the locations would be provided to the Delta Launch Vehicle guidance engineers in June 2002.The landing sites would continue to be evaluated until launch in June 2003, but only extraordinary findings would force a re-targeting of landing sites during the first TCM after launch.

Most of this material is also included in the attached viewgraph package to the project. We welcome your comments on this plan. Following incorporation of your comments we will revise the plan, begin planning the first open landing site workshop, and go forward with landing site identification and selection for the MER Project.

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