DPS: Sending humans to an asteroid?
Posted by Emily Lakdawalla
08-10-2007 20:47 CDT
I am finally in my hotel room after an exhausting first day at the 39th meeting of the Division of Planetary Sciences. The day was made more exhausting by the fact that in order to have as little impact on my 14-month-old daughter's life as possible, I didn't leave for today's meeting until after I put her to bed last night, taking an overnight flight that landed me here at 6 a.m. I'm here for two jam-packed days of the meeting, and will be home again on Wednesday.
I wanted to make the most of these two days, so over the weekend I pored over the program and developed a detailed schedule for nearly every minute of each day, determining ahead of time which of the three meeting rooms I would be sitting in for how long before jumping from one session to the next. This morning I started in Jupiter's atmosphere, learning about the "global upheval," then switched to Enceladus, then to Iapetus, then to a session on "YORP Observed!" (which I'll explain later), which took me to lunch, during which there were press briefings on Saturn's rings and on Iapetus. After lunch I learned about what's new with NEOs (Near Earth Objects), then what's going on with Uranus' equinox, then tried to sneak into the exhibit hall for coffee and kept running in to people to talk to, which made me miss the Saturn rings talks I'd planned to attend, but I did get to the "Satellite Potpourri" session before jumping to another rings session that started with Saturn and ended with Uranus. After that I debated attending the NASA "Research and Analysis Meet and Greet" but very fortunately I ran in to author Dava Sobel, who is one of my favorite people, and who didn't have a dinner partner yet, so we had a very nice dinner together and now I'm in my hotel room and wondering how I am going to write up this day!
Clearly I am not going to be able to formulate a complete description of the entire day this evening. So I'll pick just one presentation, the one that was the most different from all the other talks today and hence the easiest one to write about separately from the others: a presentation by Paul Abell from NASA's Johnson Space Center on the feasibility of a piloted mission to a near-Earth object using the Crew Exploration Vehicle, which is the thing that is going to replace the Space Shuttle. Abell was careful in his introduction to say that "this is a phase 1 technical feasibility study, not a NASA-endorsed mission concept;" in fact, they "still need to brief upper levels of NASA Headquarters, hopefully we'll do that in a couple of weeks. The work done to date is based upon only 4 ½ months of work, just to see if it's even viable."
They were required, he said, to make no major element changes, no major modifications to the rockets; they could, however, make modifications to the Orion capsule, to, say, reduce the number of crew from three to two in order to make more room for consumables. They wrote down a few "bookend" mission scenarios and established that, at least at the level of detail of this study, it's feasible to send a
crewed - piloted - dang it, those just don't sound right, I'm gonna have to stick with - manned mission to a near-Earth object. The basic mission profile would be a dual launch, with the Orion capsule launched on one rocket and an interplanetary transfer vehicle on another. The two would dock in Earth orbit and then depart for a near-Earth object, on a mission that would take 90 to 180 days with a 14-day stay at the near-Earth object; they would leave the transfer vehicle behind and just return with the Orion capsule. Abell's team even searched the current NEO database and found eight objects that have orbits that are close enough to Earth's to be feasible targets for such a mission, launching in the 2015-2030 time frame.
So, it may be possible, but what's the point of such an exercise? It would, Abell said, "expand human capability beyond Earth orbit, and actually start exploring the solar system." The astronauts could assess the resource potential of NEOs and gain operational experience peforming complex tasks with crew, robots, and spacecraft under micrograivty conditions, with Mars being the eventual goal. From a science standpoint, Abell said, the rationale is "sample return, sample return, sample return," with all the science benefits that having pristine chunks of space rocks to analyze in Earth laboratories gives you. I was most happy about the last of his rationale slides, which looked at what the public would get out of it. It would be an unprecedented deep space voyage -- an amazing adventure. It would "put humans demonstrably on the way to Mars while doing science, gaining understanding of potentially hazardous objects that would be useful in developing mitigation strategies."
It's all kind of pie-in-the-sky right now, but I think it's quite possible that, if we ever get humans out of Earth orbit, that they'll go to an asteroid before they go to Mars. There's just so many things about getting to Mars and getting back that are so hard to do; doing an asteroid mission would tackle some of those problems but not all of them at once, while doing important science and addressing the danger of potentially hazardous asteroids.
In the question and answer session that followed, someone pointed out that if they visited a small-enough body, they could accidentally do a gravity tug on the asteroid, one of the mitigation strategies suggested by Rusty Schweickart and the B612 Foundation. A manned vehicle will be pretty massive -- it could prove the concept, at least, but it's something they'd better plan carefully for, lest they accidentally tug their near-Earth object nearer to Earth!
I'm off to bed -- many more sessions to cover tomorrow!
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