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Emily Lakdawalla • Sep 27, 2010

Fourth MSL Landing Site Workshop: A review

Today, tomorrow, and Wednesday, about 200 scientists and engineers will sit in an over-air-conditioned room in Monrovia, California (which must have been one of the cool spots in the Los Angeles area) to participate in what is officially titled the "Fourth Mars Science Laboratory Landing Site Community Workshop." The word "community" is what makes this meeting different from nearly every other meeting taking place in the preparation for the next Mars landing: today's meeting (and the three like it that happened before, and the one more like it that will happen in the spring) are open to anybody. Anybody who has any interest in where the Curiosity rover will land is permitted to attend, listen to the arguments for the four possible landing sites, listen to the discussions of what Curiosity may be able to accomplish at any of the sites, ask questions, and comment.

The decision of where to land the rover will not be made by this group, either today or at the final meeting. That decision is, ultimately, the responsibility of NASA Headquarters, which will make the decision based only partially on the input of the science community. Still, I think it's remarkable (and good) that the community is invited to participate.

There are currently four sites under consideration: Mawrth, Holden, Gale, and Eberswalde. To learn more about these four possible landing sites, I invite you to read an excellent summary by Lisa Grossman over at Wired Science. This list actually hasn't changed for a couple of years. When the launch of Curiosity was delayed in December 2008, the mission did invite the wider scientific community to take advantage of the extra time to see if any new scientific results warranted the consideration of any additional possible landing site choices. Since then, although two potentially interesting sites were identified ("Margaritifer" and "Northeast Syrtis"), the mission determined that both sites had potential problems for a safe landing, and they made a formal decision to contain the sites under consideration to these four.

Curiosity's 4 Candidate Landing Sites
Curiosity's 4 Candidate Landing Sites The candidate MSL landing sites are shown in the above figures as ellipses of approximately 20 by 25 kilometers (12.4 by 15.5 miles) size. Each ellipse is placed approximately, as the exact location may change slightly as mission plans evolve. On the left is the Mawrth Vallis site, located on light-toned layered rock near 24.3°N, 19.0°W. At the center are the landing site candidates in Eberswalde Crater (near 24.1°S, 33.4°W) and southern Holden Crater (near 26.6°S, 35.0°W). On the right is the landing site candidate in northwestern Gale Crater (near 4.5°S, 222.7°W). The orange feature in Gale is a fan of sediment transported to the crater floor by a channel that cuts the crater's northwestern wall. Each figure is shown at the same scale and north is up. These are mosaics of Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) red wide angle images acquired during the May 1999 Geodesy Campaign. The data were map-projected and mosaiced by Malin Space Science Systems personnel.Image: NASA / JPL-Caltech / MSSS

What's changed in the last two years is the amount of data we have on each site. That's been two full years of data acquisition by three Mars orbiters. The real star for landing site selection is Mars Reconnaissance Orbiter with its high-resolution instruments, the HiRISE camera and CRISM imaging spectrometer. The amount of data available on the sites is actually challenging for scientists to cope with, and among the topics of today's meeting is the work being done by the HiRISE and CRISM teams to create data products that make it easier for scientists who are not members of those teams to take in, analyze, and interpret all that data.

Here's a review of what science Curiosity is intended to do when she finally lands on Mars, about exactly one Mars year from now. These words are the official ones, taken from this presentation (PDF, 2 MB). Overall, the goal is to "Explore and quantitatively assess a local region on Mars' surface as a potential habitat for life, past or present." In more detail, what Curiosity will do to achieve this goal is to:

  • Assess the biological potential of at least one target environment.
    • Determine the nature and inventory of organic carbon compounds.
    • Inventory the chemical building blocks of life (C, H, N, O, P, S).
    • Identify features that may represent the effects of biological processes.
  • Characterize the geology and geochemistry of the landing region at all appropriate spatial scales.
    • Investigate the chemical, isotopic, and mineralogical composition of martian surface and near-surface geological materials.
    • Interpret the processes that have formed and modified rocks and regolith.
  • Investigate planetary processes of relevance to past habitability, including the role of water.
    • Assess long-timescale (i.e., 4-billion-year) atmospheric evolution processes.
    • Determine present state, distribution, and cycling of water and CO2.
  • Characterize the broad spectrum of surface radiation, including galactic cosmic radiation, solar proton events, and secondary neutrons.

When Curiosity gets there, she'll be able to drive at 4.2 centimeters per second (half that if she's navigating autonomously, a quarter that if she's using visual odometry), traversing around 100-150 meters per driving sol, and she should manage to drive at least 20 kilometers over her lifetime, which should take her outside her 20-kilometer-diameter landing ellipse.

Here's some past stuff I've written about this rover, including my notes from the second and third site selection meetings. The next post -- which may not happen today, sorry -- will contain my notes from today's meeting. You can visit me on Twitter for some of the highlights if you can't wait!

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