9. Trafficability

2005: IVA-6
2010: 4
Priority: Low

(2010 Version)

4. Investigation. Assess landing site-related hazards, including those related both to safe landing and safe operations within the possible area to be accessed by possible elements of a human mission.

A successful human surface mission would need to land safely at a site of significant scientific interest, and in terrain that would allow the astronauts to move about the site as part of their exploration activity. We know from experience with site selection for past robotic landers/rovers that sites with some of the most interesting scientific attributes also tend to have more difficult and risky terrain. Correctly understanding the trade-off between landing site hazards and expected scientific return for a crewed mission would be fundamental to realizing the full potential of sending humans to Mars. Landing site-related hazards can be grouped into two categories: 1). Hazards related to landing safely, and 2). Hazards related to the various movements at the martian surface needed to achieve a mission’s objectives. Hazards in both areas are capable of causing mission-ending failures. In the case of safe landing, we know from experience with prior Mars landers that the following four factors are particularly relevant: the size and concentration of surface rocks, terrain slopes, and the concentration of dust. The specific safety thresholds for these parameters depends on the specific design of the mission (for example, ground clearance provided by landing legs), but we know from prior experience that these factors have to be considered carefully for all landed missions at Mars.

In order for landed human missions to achieve their objectives, movement across the martian surface would be required. This may manifest itself in establishing and maintaining necessary surface infrastructure, or in accessing specific scientific targets. Thus, trafficability hazards need to be considered. In the case of MER, both Spirit and Opportunity became embedded in soft soil while driving. Opportunity was able to extricate itself and continue driving, but Spirit was not. Other trafficability hazards include rock fields and steep slopes. Although the operation of the MER rovers has significantly improved our general understanding of the issues related to trafficability on the martian surface, an assessement would need to be made on a site-by-site basis given the range of mobile elements associated with a human mission.

Measurements:

Source:
MEPAG Goal IV Science Analysis Group (2010). “IV. Goal: Prepare for Human Exploration.”
Proposed replacement text for MEPAG (2008), Mars Scientific Goals, Objectives, Investigations, and Priorities. Submitted 2 August 2010.