Onward to Cabeus A!

Friday, September 11th, 2009

I just got finished with watching, on NASA TV, a press conference at Ames Research Center to announce the target crater of the LCROSS mission. Before the selection was revealed, though, project manager Daniel Andrews announced some unexpected news. NASA has now dedicated the LCROSS mission to the memory of Walter Cronkite, the famous news anchor for CBS television who was for so many people the voice of the space program in the 1960s and early 1970s. A wonderful gesture!

Walter Cronkite tries out a lunar gravity simulator, in 1968 (NASA photo)

“Dad would be very pleased to be part of this process,” said Chip Cronkite, Walter Cronkite’s son, who was at the news conference. He also expressed the hope that, if water is indeed found at the lunar south pole, “once you build a fuel station there, we’ll have another renaming.”

After that announcement, Tony Colaprete announced the target crater: Cabeus A, a 40-kilometer wide crater that is at approximately 81 degrees south latitude. He outlined the four main criteria on which the selection was based and why Cabeus A satisfied those criteris:

• Flat topography that does not block the visibility of the ejecta
• “Fluffy” terrain that is smooth and boulder-free, with slopes of less than 5 degrees
• Existing evidence of water ice in the crater
• Visibility from Earth

Cabeus A was especially attractive in terms of the last two criteria. The best evidence for water comes from the neutron spectrometer that flew on the Lunar Prospector mission (late 1990s) and the more accurate neutron spectrometer that is flying on the LRO mission right now. These instruments detect neutrons coming from the moon’s surface, and a dip in neutrons of a certain energy (“epithermal neutrons”) indicates the presence of hydrogen. Note that this method only detects hydrogen — it does not discriminate between water and other hydrogen-containing molecules! Conceivably we could be seeing methane or hydrocarbons. We won’t know until the LCROSS mission tells us. But in any case, Cabeus A has one of the best “sweet spots,” as Colaprete called it, where the concentration of water ice (assuming that is what it is) exceeds 2 percent.

Also, Colaprete pointed out that Cabeus A offers excellent viewing. Because it is a little farther from the south pole than some of the other candidates, it is easier for Earth-based telescopes to see, and as proof he showed a photograph taken from the Apache Point observatory (one of the six large Earth-based observatories that will watch the impact), in which the crater shows up very clearly.

Colaprete said that the impactor will be targeted to within 3 kilometers and probably quite a bit more accurately than that. One of the reporters asked when the results from the impact would be known. Colaprete said they will know almost immediately whether the experiment has been a success, in terms of the size of the debris plume and whether it has been seen successfully by the LCROSS spacecraft and ground telescopes. They will probably want to take a little time to determine whether they have seen water ice, and of course, it will depend on how much they see. He said they are required to report the results within 3 months of the impact, and he mentioned 30 days as a more likely time frame.

One other interesting question concerned LCROSS’s fuel usage. At one point last month, when the spacecraft was out of the controllers’ view, there was what Andrews called an “anomaly in an avionics element.” Basically, the spacecraft was burning a lot of fuel when it wasn’t supposed to. When they realized what was happening, they were able to shut down the burn. But the result was that, instead of having a lot of extra fuel, the spacecraft now has just enough. “Fuel efficiency is now incredibly important,” said Andrews.

Andrews explained that the fuel tank in LCROSS isn’t like the gas tank in your car, which has a float in it that tells you how much fuel you have left. If you think about it, a float would not work very well in zero gravity! So there is a little uncertainty over how much fuel is left, but even in the worst-case scenario they are confident that they have enough to complete the mission successfully.

You might think that an unscheduled fuel burn might have taken the spacecraft off course or made it start tumbling, but none of that happened. In fact, LCROSS is so perfectly on course that they have canceled three trajectory correction maneuvers, including one that was scheduled after the “anomaly” happened.

Stay tuned, and get ready to point your telescopes at the Moon’s south pole at 4:30 am (Pacific time) on October 9!

P.S. Although it’s unlikely, I would be very interested to see what would happen if we found methane or hydrocarbons at the lunar South Pole instead of water! That might generate quite a bit more interest (and money) for going back to the moon. I’m not sure whether it would be a good thing, though – once the oil companies got involved, it would be very hard to preserve the moon as a resource “for all mankind.”

How could there be methane at the lunar South Pole? Well, it kind of depends on how ubiquitous it was in the early solar system. The permanently shadowed craters are good traps for any kind of volatile (i.e., easily vaporized) molecules, not just water. We’ve seen that there is lots and lots of methane on Saturn’s moon Titan — why not our own?

Another interesting point that Colaprete brought out is the fact that we have no idea how much hydrogen/water/whatever is present below the surface. The neutron spectrometers only see hydrogen that is less than a meter from the surface. So we could in fact have huge concentrations of water ice farther down, and we wouldn’t know it. Hence, once again, the incredible importance of an impact mission, which will excavate material from a depth of several meters.

Posted in Missions, NASA, Science | No Comments »

Need $3 Billion, Please

Wednesday, September 9th, 2009

Yesterday the U.S. Human Space Flight Plans Committee, also known as the Augustine Committee, released its report on the future of NASA’s human spaceflight program. Although I’ve read some criticism of their report online, I think the criticism is all of the “Shoot the messenger” variety. The committee did its job really well.

The report sets out some basic and unpleasant truths that people have been averting their eyes from for a long time. It also laid out five reasonable scenarios for how NASA can move ahead. Even though this was not a decision-making committee, it did actually rule out a scenario that was unrealistic, which I thought was quite an accomplishment. The committee has provided in clear language the basis for the true decision-makers to make a decision. Now we’ll see if our leaders can step up to the plate — or, to use a more appropriate sports analogy since we have an ex-basketball player in the White House, we’ll see if they can sink the winning 3-pointer with the clock running out.

Here are four options that the committee has said are feasible, plus the one that it said was not feasible at this time. (The report actually split option 3 into two sub-options.) Some of the names are theirs, and some are mine.

1) Moon Never, aka Napoleon’s Retreat. In this scenario, NASA continues with both its current budget and current objectives, which are incompatible. The shuttle is mothballed in 2011. The International Space Station is ditched into the Pacific Ocean in 2016. We continue spending money for a moon program that will never happen: “There are insufficient funds to develop the lunar lander and lunar surface systems until well into the 2030s, if ever,” the report says. This option is basically a full-fledged retreat from manned space exploration, with a fig leaf of ongoing research to cover our embarrassment.

Don’t laugh. This is probably the most likely option. Napoleon didn’t want to retreat from Russia, but he did.

2) Moon Never, ISS on Life Support. Slightly more palatable, this option also abandons hope for sending humans beyond low Earth orbit, but it at least acknowledges that it would be a disgrace to build a space station for 25 years, operate it for 5 years, and then torpedo it. The Augustine committee said that we can keep the ISS going to 2020 by developing a smaller heavy-launch rocket and relying on commercial companies to generate cheaper alternatives for launching humans into orbit. A slightly larger fig leaf.

3) Moon First. The committee says that we can keep on track for returning to the moon in the mid-2020s (not 2020 any more) if NASA’s budget is increased by $3 billion per year, plus reasonable cost of living increases thereafter.  “At this budget level, both the Moon First strategy and the Flexible Path strategies begin human exploration on a reasonable, though hardly aggressive, timetable. The Committee believes an exploration program that will be a source of pride for the nation requires resources at such a level,” the report says. Again there are various options based on how big a launch vehicle we want and how much help we can expect from commercial space services.

4) Flexible Path. This option includes lunar fly-bys, visits to Lagrange points (which are the gateways to low-energy transportation to many other places in the solar system), near-Earth objects (such as asteroids), and eventually Earth’s moon or the moons of Mars. The committee clearly likes this option because it is new and different from what has gone before, but it does not actually endorse the Flexible Path over Moon First.

5) Finally, it’s notable that the report rules out the Mars First option, even though it had visible and outspoken advocates, such as Buzz Aldrin. “The Committee finds that Mars is the ultimate destination for human exploration; but it is not the best first destination.” Translation: We can’t do it yet. In spite of what Apollo did in the 1960s, you can’t just leapfrog over two or three generations of technology. (Apollo did leapfrog a generation or so, but only with an extraordinary outlay of money — and I don’t think anyone except Aldrin believes that can happen again.)

In light of the report, the U.S. government has two big decisions to make. The main one is: Do we want a manned space program or do we want a public relations agency? I think that if the question were posed to most Americans in that form, they would rather spend $21 billion for a bona fide human flight program with clearly stated and achievable objectives, rather than spend $18 billion for public relations and for plans on the drawing board that will never be achieved. To come up with those $3 billion, especially in these economic times and in this political climate, would be Obama’s version of hitting a 3-point shot at the buzzer.

The subsidiary question, which is nevertheless important, is: After we have made our choice, what is our strategy? If we can’t afford a manned space program beyond low Earth orbit, we have to decide on which fig leaf to cover up our failure with.

If we can scrape up $3 billion, do we opt for Moon First or the Flexible Path? The question is important because the choice will affect how and whether you can sell this option to the public.

The Flexible Path would give Obama more of a chance to put his own stamp on the space program, rather than following in Bush’s footsteps. I would think that would be very attractive to him. However, as Paul Spudis argues in his blog, the benefit of Moon First is that you are building infrastructure. You don’t have to stake your case on inspiring the public, part of which has never been enthusiastic about the space program anyway. You can work on uninspiring but nevertheless achievable goals, with a long-term aim of making space economically relevant. If you are trying to extend human presence to a new realm, one-time sorties won’t do it; eventually you have to set up a base or a colony. The moon is the only place for that in the near future or even the medium future.

As you can see, I think that Moon First is a little bit more sensible. But I completely acknowledge that I am biased because this is a moon blog. If the Flexible Path is the only way to sell a $3 billion increase to the American public, then I would be glad to support that instead.

Finally, let’s talk about that $3 billion. How much of a burden is it, really? A look at the history of NASA’s budget on Wikipedia is really eye-opening. As a percentage of the Federal budget, NASA’s budget is lower than it has ever been since John F. Kennedy was elected president in 1960. We are talking the talk of doing great, ambitious things, but we are not walking the walk.

If we miraculously find $3 billion more for NASA, that will raise its percentage of the Federal budget from 0.52 percent to 0.60 percent. Such extravagance! Such profligacy! Would this take us back to the days of Apollo? Hardly. It would take us all the way back to the days  of 2008, the last time NASA represented 0.60 percent of the budget. By comparison, during the buildup to Apollo, NASA’s budget peaked at 5.5 percent of the Federal budget, or ten times as much as today.

So, all things considered, I really don’t think that $3 billion is too much to ask. In fact, I hope that the experts will scrutinize the full report, when it is released, to make sure that we understand that $3 billion figure and make sure that it will really do the job. If so, Obama and Congress should sign off on it gladly, because they are getting a bargain.

I’d like to end on a humorous note. Once a week, I drive senior citizens to doctors’ appointments. Today’s passenger, Lloyd, is a little bit hard of hearing but compensates for it with a great sense of humor. For example, I overheard his nurse asking him today, “Have there been any signs of bleeding lately?” To which he replied, “Signs of breathing? No, no signs of breathing!”

While we were in the waiting room Lloyd was reading a newspaper and came to a headline about the Augustine report: “NASA Told U.S. Can’t Pay for New Moon Flight.” He joked, “New moon flight? Why, there’s a new moon every month!”

Posted in Just for Fun, Media, Missions, NASA | 3 Comments »