Saturday, March 27, 2010

Moon First, for Robotic Exploration

"NASA will immediately begin to realign programs and organization, demonstrate new technical capabilities, and undertake new robotic precursor missions to the Moon and Mars before the end of the decade."
  - President George W. Bush, Vision For Space Exploration, 2004.

“What is needed is a carefully thought out plan to characterize and demonstrate ISRU on the lunar surface first with a series of robotic precursor missions, building up knowledge and capability with time, and ultimately supporting and provisioning human presence on the Moon. Such an architecture is possible within the proposed budget envelope.”
  - Dr Paul Spudis, The Once And Future Moon, 2010. 
(and you have no idea how much violent agreement went into getting that quote.)

There's no question that robotic missions are valuable precursors to manned missions.  Without the results of the seven spectacular Surveyor landings the design of the Apollo missions would have been a lot different, and may not have worked at all.  And yet, since the Surveyor program ended in 1968 we've not sent any robotic exploration missions to the surface of the Moon.  Why is that?

It can't be a matter of budget.  If the Google Lunar X-Prize is anything to go by, the robotic rovers that land on the Moon towards the end of 2012 will be doing so to win a $20 million prize - and to be first in line for the pent-up demand for lunar science missions from universities and "sovereign customers" around the world.  The much more ambitious NASA Mars Pathfinder was developed, flown and operated for under $280 million, over 4 years.  The two Mars Exploration Rovers (Spirit and Opportunity) have been wildly successful and with five mission extensions only cost about twice as much as Pathfinder to develop and operate yearly.

To many the answer is obvious: the Moon has been explored and there's nothing more to learn.  Any lunar geologists reading this will be yelling at the their screens right now.  The vast majority of the Moon has not been explored.  The geologic history of the Moon remains a matter of guesswork and this has implications for our understanding of the Earth's own geologic history.  A lot of the guesswork was made substantially less error prone by the samples returned with the Apollo astronauts, but many mysteries remain.  Unexplored lunar features include: nonmare domes, rilles, potentially active volcanic vents, the entire far side, and permanently shadowed craters.

It is the last of these which have gathered the most interest lately.  October 9, last year, the LCROSS probe impacted into the south pole of the Moon causing a brief debris plume which NASA/Ames researchers eventually told us indicated the presence of water.  March 1, this year, results from the NASA Mini-SAR instrument on the Indian Chandrayaan-1 lunar orbiter and the Mini-RF instrument on NASA's Lunar Reconnaissance Orbiter were announced, with an estimate that approximately 600 million metric tons of water are present in permanently shadowed craters at the north lunar pole.  This comes hot on the heels of a general announcement that the Moon is a much wetter place than was previously believed.

I won't continue to ask the question why no robotic landers have been sent to the Moon since Surveyor, and why no lunar rovers have been sent to the Moon by NASA, ever, because the answer, at least since 2004, is a matter of public record and a sore point to many.  Let's just say it's a matter of budget priorities and leave it at that.  The question is, with all these exciting discoveries by orbiting robotic vehicles, have those priorities changed?

I've recently heard rumors that they have.  The feeling is that NASA is ramping up to send a highly dexterous robotic payload on an autonomous lander to the lunar surface - to do what mission I have not heard.  Now, let me be clear - I hate rumors.  I despise the *wink* *wink* half-admissions that people in the know - or people who think they are in the know - make when asked for a straight answer.  But what I hate more is being told to shut up.  And this loggerheads of the search for the truth and the desire to keep a secret often leads to frayed tempers and friendships.  So what evidence do I have so far for this rumor that just won't go away?  Oh, I wish you hadn't asked that.

Armadillo Aerospace are working on a methane/LOX propellant vehicle for NASA.  It's not 100% confirmed to me that this is for the Autonomous Landing and Hazard Avoidance Technology (ALHAT) program.  The vehicle will be used to field test sensors such as LIDAR and algorithms for terrain analysis algorithms, terrain and environment modelling, hazard detection, and terrain relative navigation developed at JPL (who also built and operates the Mars Rovers).

The CEO of Masten Space Systems tells me that he recently received a briefing at JSC on ALHAT and how it fits into an unofficial policy they are calling Project M.  To me, this remains the most baffling piece of evidence as I had heard of Project M already and declared it to be an "obvious hoax", belittling a number of people who accepted it as real without even a second thought.  I've since had to apologize to those people as it has become increasingly obvious that I was wrong.

What makes Project M seem so implausible is that a primary element of the visual presentation is a bipedal humanoid robot that appears to be untethered - that is, it has sufficient power to maintain an upstanding posture.  This is something that many of us have become accustomed to seeing with the Honda ASIMO being the most prominent example.  But ASIMO has a continuous operating time of only one to two hours (it was once only 20 minutes and has gotten better as battery technology has improved).  An argument could be made that the Moon's 0.16 gravity reduces the power requirements for locomotion, but a counter argument could easily be made that the lunar gravity makes it harder to test bipedal locomotion algorithms - which remain some of the hardest tricks for roboticists to pull off here on Earth.  As such, my willingness to believe in the existence of Project M extends so far as to suggest that if the legs were replaced with a suitable wheeled rover, then it may be plausible to send a highly dexterous humanoid robot to the Moon.

The last piece of evidence I have is not so much evidence as compounding rumor, and that's one of the problems with rumors, they spread like cancer.  The humanoid robot most likely to be used for Project M is the Robonaut 2 being built for NASA by GM, and it will be flying to the International Space Station in the Permanent Multi-purpose Module on the last shuttle flight, STS-133.  Whether this is true or not is not really that important, but it does suggest that the JSC team that work on the Robonaut project are confident that the robot could be ready for flight testing.

In case you're wondering, I've asked a NASA Public Affairs Officer for confirmation or denial of Project M, but to-date I haven't received a reply.  I'll keep you posted.

What could be the mission of Project M?  Most likely it is just to be a showcase of robotic technologies.  Ho Hum.  So a better question may be: what would be a good - and by that I mean productive - mission for Project M?  A highly dexterous humanoid form of robot is best utilized in the teleoperated performance of undefined or at least unexpected tasks.  If a scientific instrument is malfunctioning, a Robonaut may be teleoperated to repair it.  Thinking bigger, preparing a lunar base for habitation by humans that will arrive later sounds like the kind of open-ended goal that would inspire the use of a teleoperated Robonaut.  But I want to suggest something else.

In what form is the water in the permanently shadowed craters at the lunar poles?  Is it pure ice, or slushy regolith, or bone dry but with a little more water than elsewhere? Characterizing the water of the Moon is good science, but its not *just* good science.  The water of the Moon is the first real resource of space that has been universally recognized as a strategic asset.  For human life support it can be made into oxygen for breathing and, well, water for drinking.  For space transportation it can be turned into methane and liquid oxygen to be used in rockets like the ones Armadillo Aerospace have developed, and in fuel cells that may one day be used on Mars.  But to start thinking about utilizing these in-situ resources we have to know what form they are in.  A robotic mission could tell us that.

On the other hand, the possibilities are a lot more clear now than they were just a year ago.  Before LCROSS, Mini-SAR and Mini-RF it wasn't even clear this was water we were talking about.  To be conservative one had to say "hydrates", causing some in the public to wonder if we were talking about breakfast cereals.  I can imagine lunar ISRU advocates reading this yelling at their screens that we already have enough "characterization", let's get to work already!  Of course, not everyone agrees with me.  How boring would the world be if they did?  It's not exactly complicated engineering but its never been done before and a robotic precursor sounds like a prudent approach.

Jon Goff, and others, have suggested that a robotic ISRU mission would be unlikely to work "first time".  However, I don't think Jon was considering the possibility that there may be pure ice at the lunar poles and I don't think he has the same kind of robotic mission in mind as I do.  With a highly dexterous teleoperated robot, like Robonaut 2, there's leeway to tinker.  The ISRU plant doesn't have to work first time, it can be repaired (we have the technology).

It makes sense for Project M to use a methane/lox based lander.  That opinion dates back to ESAS and for the same reason, those propellants are derivable from lunar resources.  It also makes sense to propose that the lander be reusable.  If you guess the wrong crater to land in first time, it makes more sense to put the rover back on the lander and hop to another one.  A reusable lander also can serve as part of a lunar transportation system, delivering water and propellant to lunar orbit, and collecting supplies to take to the surface.  Highly efficient solar-electric tugs can cheaply ferry water or propellants from lunar orbit to lagrange points or even to low Earth orbit, drastically reducing the cost of getting humans to the Moon, Mars and beyond.

Oxygen freezes at 50.5K and boils at 90.19K.  Methane freezes at 91K and boils at 112K.  As such, liquid oxygen is likely to be a liquid in lunar cold traps estimated be at around 40 to 60K, and possibly even a solid, whereas methane is almost certainly going to be a solid, neither will experience boil-off.  Think about that for a minute.  The closest place, off the Earth, that we have found water ice is cold enough to permanently store some of the best rocket fuel we've developed, with zero boil-off.. possibly without even the need for tanks.  That is a very exciting proposition.

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