PASADENA, California - When NASA's next wheeled robot--the Mars Science Laboratory--rockets skyward in 2009, the mega-rover will carry the largest, most sophisticated array of science gear ever shot to the martian surface.
Far more robust and powerful than those smaller robotic look-alikes now laboring on Mars--Spirit and Opportunity--the Mars Science Laboratory (MSL) is intended to turn a new page in planetary exploration.
But here's the issue at hand: Where to land the hunk of high-tech machinery; deciding the ideal spot that's safe but also maximizes the rover's chances to help figure out if Mars ever was--or is today--an abode for life.
Leading Mars investigators and space engineers are gathered here this week at the first landing site workshop for the 2009 Mars Science Laboratory.
The purpose of the workshop is to hear about all of the proposed MSL landing sites ... and to make a first cut at prioritizing them, said John Grant, a geologist at the Center for Earth and Planetary Studies at the National Air and Space Museum in Washington, D.C.
Grant also co-chairs the MSL landing site steering committee that organized this week's meeting.
"All of the sites will probably remain under consideration after this first workshop, but they will be prioritized into high, medium, and low groups," Grant said. A key job of workshop participants is to help in this categorization; a task that then assists in targeting the various prospective landing sites by the fleet of probes now orbiting the red planet--particularly NASA's new arrival, the Mars Reconnaissance Orbiter.
As part of this week's intensive workshop, MSL engineers will advise the gathered scientists about restrictions and limitations in landing and running the large rover on Mars.
"Engineering constraints are critical ... because if the rover does not land safely you don't get any science," Grant advised. "And once the rover lands, the rover needs to be able to move around."
Latitudes and attitudes
Grant said that the current site constraints are very broad and allow consideration of sites at a range of elevations and latitudes not considered by Spirit and Opportunity Mars rover planners, for example.
Also, the science constraints for MSL are pretty clearly spelled out.
"Obviously, the more and higher priority relevant science targets a site possesses, the higher it may be ranked. It may require additional data--such as from the Mars Reconnaissance Orbiter--to assess what engineering risks and science potential the various proposed sites have," Grant told SPACE.com. Hence, the desire to rank sites high, medium, low at this first workshop.
It's already clear that where MSL could be targeted stirs up healthy debate and competition between Mars experts.
Some scientists here are backing the Holden Crater region. Others suggest that Gale Crater is a feature likely to rise to the top of the must do list. Many point to a "no brainer" of an exploration hot spot--the huge canyon landscape of Valles Marineris.
"Valles Marineris looks good now ... but remember the cold feet that the engineers got about this with Spirit and Opportunity. I wouldn't be surprised if Valles Marineris eventually falls out of favor for engineering reasons," predicted one Mars researcher taking part in the workshop.
Finding the right balance
For sure, getting a rover on the red planet isn't a walk in the park--in terms of where to land and other judgments necessary. Just ask somebody that's gone the distance.
"One of the hardest things about picking a landing site is finding the appropriate times to make decisions," said Steve Squyres, lead scientist from Cornell University for the Spirit and Opportunity rovers already wheeling about Mars.
"From an engineering perspective, you want to make the decision as soon as possible. The sooner you know where you're going--at least in general terms, like latitude and altitude--the easier it is to come up with a spacecraft and mission design that'll perform well under those particular conditions," Squyres told SPACE.com in an earlier interview.
However, from a science perspective, Squyres noted, you want to make the decision pretty late in the process.
"Orbiters overhead are always collecting more data and scientists are always looking at the data ... so the longer you wait, the more you know. We worked hard to find the right balance ... and Mars Science Laboratory is dealing with the same issues."
Science payload progressing
Winds, rocks, the slopes of terrain are part of the appraisal of where best to put Mars Science Laboratory down on the planet, said Richard Cook, MSL Project Manager here at the Jet Propulsion Laboratory (JPL).
Not only is the new and powerful Mars Reconnaissance Orbiter (MRO) to be used to help certify an MSL landing zone. "It's also possible that MRO will see something particularly interesting that will add sites to the candidate set," Cook explained.
Cook told SPACE.com that the science tools MSL will tote is coming together. "The payload is sort of out in front of the rest of the project," Cook said. "We're far from out of the woods...but things seem to be progressing along in a pretty good way."
At this stage, both the MSL design and which landing site may be of interest are maturing at the same time, Cook said. "If we were going to pick a landing site right now, I'd be a little more concerned. The engineering assessment [for MSL] may evolve over time."
Holy Grail: a habitable environment
Cook said that the "on-paper process" calls for an MSL landing site to be chosen a year before the rover's launch in the fall of 2009. "Unless something happens to change that, that's what we'll do."
The MSL mission, including cost of a launcher, is about $1.5 billion, Cook said. A decision on what booster will hurl the rover long range to Mars is near at hand, he said.
Once on Mars, the large nuclear-powered rover is to assess whether Mars ever was, or is now, a world that supports microbial life--a mission to determine the planet's habitability.
"That's the Holy Grail of what we're trying to do," Cook said, to find a site that optimizes the chance of proving that it's a habitable environment. "That's what the scientists have to wrestle with ... and there's a diversity of opinion about how to improve the chances of finding what we're looking for."
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