Rovers are awesome, but where's the science?
Posted by Emily Lakdawalla
05-12-2012 15:55 CST
Now that Casey has explained the budget implications of yesterday's 2020 rover announcement, and The Planetary Society has issued a formal statement, I thought it was time for me to talk briefly about science.
A quick summary of the situation: NASA announced yesterday that the next Mars mission will be a rover based on Curiosity, in fact using many "spare parts" from that mission (but not science instruments), to be launched in 2020. Because it will be reusing existing design and some hardware, they project the mission cost, including launch vehicle, to be $1.5 ± 0.2 billion, an estimate from an Aerospace Corporation study. The Planetary Society has looked at the announcement and, as far as the budget is concerned, there's no change to policy here: NASA has merely given a name and shape to a line that already existed. There's no impact to other programs -- at least no more impact than is already being suffered from the $309 million cut that we have been fighting to reverse.
Another Curiosity, sent to a different location (my money right now is on Mawrth Vallis), could be a tremendous addition to and extension of our Mars program, so I'm excited about that. But I have some big concerns about this announcement, which boil down to this: it doesn't seem to me that science was any part of this decision, and I'm afraid of the consequences of a science-free mission selection.
Last year, the planetary science community completed an arduous, years-long task at the behest of NASA: to lay out a decade's worth of plans for the future of NASA's scientific exploration. The product, called "Visions and Voyages for Planetary Science in the Decade 2013 -- 2022 (PDF)", is usually referred to as the "Decadal Survey." Now, I may say it was produced by "the planetary science community" but this so-called community is not monolithic. There are all kinds of factions, and it was a monumental effort to produce a document that enough scientists could agree on that you could claim it had broad support. The Decadal Survey may have flaws, but it represented the best consensus that planetary scientists could achieve.
The number-one priority for a large mission given in the Decadal Survey was "MAX-C," the codename for a future Mars rover. Here's the executive summary (emphasis mine):
The highest priority large mission for the decade 2013-2022 is the Mars Astrobiology Explorer-Cacher (MAX-C), which will begin a three-mission NASA-ESA Mars Sample Return campaign extending into the decade beyond 2022....
If a cost of no more than about $2.5 billion FY2015 cannot be verified, the mission (and the subsequent elements of Mars Sample Return) should be deferred until a subsequent decade or cancelled....
And from later in the document, Chapter 6, which outlines the proposed future Mars program in more detail, and explains the science involved in the decision:
The committee, building on numerous community assessment groups, open discussions, and white papers, places as the highest priority Mars science goal to address in detail the questions of habitability and the potential origin and evolution of life on Mars. The committee carefully considered the alternative of several rover missions instead of sample return. It is our opinion that sample return would have significantly higher science return and a much higher science-to-dollar ratio. Thus, a critical next step toward answering these questions would be provided through the analysis of carefully selected samples from geologically diverse and well-characterized sites that are returned to Earth for detailed study....
MAX-C is the critical first element of Mars sample return and should be viewed primarily in the context of sample return, rather than as a separate mission that is independent of the sample return objective. The MAX-C mission, by design, focuses on the collection and caching of samples from a site with the highest potential to study aqueous environments, potential prebiotic chemistry, and habitability. In order to minimize cost and focus the technology development, the mission emphasizes the sample system and deemphasizes the use of in situ science experiments. This design approach naturally leads to a mission that has a lower science value if sample return does not occur. However, exploring a new site on a diverse planet with a science payload similar in capability to that of the MER rovers will significantly advance our understanding of the geologic history and evolution of Mars, even before the cached samples are returned to Earth.
The rover that NASA announced yesterday is absolutely not the mission described in the Decadal Survey. It is not a small one based on MER with a lower science value than Curiosity because the science will happen back on Earth with samples returned through two later missions. It may not even cache samples at all. We actually don't know what it's going to do, because no scientific goals for the mission were mentioned in the announcement. The reason they weren't mentioned is because NASA doesn't know what the scientific goals are yet; those are yet to be defined, by a Science Definition Team.
This is utterly backwards. We do scientific exploration of the solar system to answer scientific questions as a part of a grand overall strategy to understand our origins and our "place in space," as my boss likes to say. We don't just say we're sending ships somewhere and explain why later. We went through a difficult and also expensive process to identify and prioritize our questions, and wrote them down in the Decadal Survey, and NASA appears to be ignoring that process entirely here.
Ignoring that scientific consensus is a big problem on its face. But there's another problem lurking behind it. The planetary science community has been flogged over the last two years to rally behind the Decadal Survey. "Don't stand in a circle and shoot at each other," we were advised. "You're more likely to get more funding for space science if you speak with one voice in support of the Survey." Surprisingly, the diverse, fractious group of planetary scientists actually did that. In particular, outer planets scientists bought the argument that they should be arguing for MAX-C if they wanted to see NASA's budget do anything but go farther down. By ignoring the Decadal Survey in their announcement, NASA risks re-fragmenting the planetary science community. And that would be really bad for planetary science.
Honestly, I'm not sure what planetary scientists should do right now. I do know one thing, and that's that we are stronger together than we are apart. If we start fighting amongst ourselves now, we won't be able to change what's going on.
I do think that fans of Mars exploration need to be shouting about NASA not following the Decadal Survey right now, if this fragile coalition is to hold together. Where is the science in this mission? Why aren't its goals already the ones outlined in the Decadal Survey? Is this going to lead to sample return? If not, what was the point of wasting so many hours of professional lives -- and so much taxpayer money -- on the Survey process?
I'm told that after the NASA town hall yesterday, Steve Squyres -- project scientist for the Mars Exploration Rovers, but more importantly in this context, the leader of the Decadal Survey process -- stood up and said (and I'm paraphrasing): the scientific community has spoken via the Decadal Survey. We have said what the payload should be already, and it should be sample caching. That's a start.
I love rovers, and I also know that rovers are popular among the public. We definitely need to pay heed to what the public wants, and I know that their goals are not necessarily driven by scientific considerations. For better or for worse, the public prioritizes boldly going where no one has gone before, seeking out new life and new civilizations and all that. I am not immediately convinced that what the public really wants is a copy of Curiosity. Where's the new adventure in that? It's certainly not leading us any closer to the things the public care about: sending people to Mars, getting a chance to travel to space themselves, or looking for alien life.
Are you a fan of science? Are you a fan of using our precious resources to advance the understanding of the questions that the scientific community has agreed are most important? Do you want to see NASA attempt new challenges, like Mars sample return, or a Europa orbiter, or a Titan boat, or human exploration beyond the Moon? If you are and you do, it's time to let NASA know that, and let NASA's paymasters -- the legislative and executive branches -- know that. Make your voices heard.