A committee reviewing NASA's goals has outlined a scheme to send astronauts on progressively longer space trips – including dockings with asteroids and flybys of Venus – to prepare for an eventual landing on Mars.
The White House set up the committee, chaired by former Lockheed Martin CEO Norman Augustine, to review NASA's plans for human spaceflight, which are currently focused on returning astronauts to the moon by 2020.
It is examining NASA's current plans and exploring alternative destinations and hardware that NASA could pursue.
Committee member Edward Crawley of MIT presented a short list of possible destinations for future human missions at a public meeting on Thursday in Cocoa Beach, Florida. He is the head of a subcommittee that is investigating options for exploration beyond low-Earth orbit.
One of the options the team proposed is called the "flexible path", which Crawley also described as a "deep space" or "in space" option.
It would see astronauts sent on a series of progressively longer missions beyond low-Earth orbit. The first would fly by the moon. Later missions would include rendezvousing with one or more of the many asteroids on orbits that take them close to Earth. Asteroid missions would take several months each.
Later, astronauts could fly by Mars and Venus, and touch down on Mars's 27-kilometre-wide moon Phobos. Each of these missions would take more than a year.
Long missions
Crawley argued that this kind of activity would help pave the way for eventual human missions to the Martian surface.
Preparing for such missions requires gaining more experience in operating on the surface of bodies beyond Earth, Crawley said. But it may actually be more critical to gain experience with long-duration space missions far from Earth, which human missions to Mars would require, he said.
"It is true we need to gain experience exploring planetary surfaces, but in fact we've done some of that," he said at the meeting. "There have been six piloted missions to the moon and we have a robust robotic programme that explores planetary surfaces. What we actually have almost no experience at all with is operations in deep space."
Such missions would require learning how to deal with the hazard of space radiation, he said. Exposure to energetic charged particles from the solar wind and sources outside the solar system could put astronauts on lengthy missions at increased risk of cancer and even cognitive problems. Spacecraft in low-Earth orbit, such as the shuttle and the International Space Station, are protected from these particles by the Earth's magnetic field, but astronauts travelling farther afield would not benefit from this protection.
Flyby spacecraft
An advantage of the stepwise approach is that the difficult job of building landers and surface equipment could be deferred, since early missions would be restricted to flybys or rendezvousing with small objects that have negligible gravity – a process that would resemble docking with another spacecraft.
Although Crawley did not give a specific year by which the first human mission to an asteroid could occur, he said it could happen within six years of starting a project to accomplish this goal.
The other options on the subcommittee's shortlist were:
• Mars first: Cancel the return to the moon and focus on sending humans to Mars instead.
• Lunar global: Have astronauts land in many different places on the moon's surface, with the option of eventually building a lunar outpost, but focus on doing things there that really help prepare the way for human Mars missions. In one version of this option, hardware would be designed from the beginning to be used on Mars, with the moon missions serving to test it.
• Continue with the current plan, which aims to return astronauts to the moon by 2020 and eventually build a permanent lunar base. Meeting the 2020 deadline would presumably require an increase to NASA's budget.
• Continue with the current plan, but keep within the budget currently expected for NASA by slowing the schedule.
• Continue with the current plan, but cancel the Ares I rocket designed to put a crew capsule in low-Earth orbit. In this case, NASA would build only the more powerful Ares V rocket, which is capable of sending crew and cargo to the moon.
Members of the subcommittee said the list was preliminary, and want to study the options further before making recommendations to the full committee. Even then, the full committee could choose to make changes before it submits its final report to NASA and the White House by 31 August.
Cost estimates
Panel member Bohdan Bejmuk, a former manager of space shuttle-related work at the aerospace company Boeing, said he was excited by the options Crawley proposed, but wondered how affordable they would be. "I'm thinking, 'God what is this going to cost?' Seriously, I'm thinking half a trillion dollars for some of the stuff you're talking about." No cost estimates were provided during the meeting.
Crawley's subcommittee also came out strongly in favour of creating fuel depots in space as a way to facilitate exploration beyond low-Earth orbit. Without fuel depots, rockets heading for the moon or beyond must be powerful enough to haul up all the fuel they need from Earth's surface, in addition to any useful payload they intend to carry. That means only very large and expensive rockets can carry out human missions to the moon.
But smaller, cheaper rockets could get the job done if they could fuel up in low-Earth orbit before continuing to their final destination. The fuel could be delivered to the depots by relatively small rockets – a process that advocates say would provide a market to stimulate commercial development of new and perhaps cheaper launch vehicles.
The Augustine committee has been asked to present an array of options in its final report, rather than endorse a single plan for NASA's future human spaceflight activities.
www.newscientist.com NASA panel may propose 'deep space' crewed missions
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This is the kind of stuff NASA has been needing to do for a while.
/Let's go to Mars.
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Wherever they burn books they will also, in the end, burn human beings. ~Heinrich Heine, Almansor, 1823
?I wouldn't recommend sex, drugs or insanity for everyone, but they've always worked for me.? - Hunter S. Thompson
30 Jul 2009, 11:41 pm
The only thing done with humans crew in sapce program for the past thirty is turning aroud the earth again and again and again and again.... Can't wait to see humans on a asteroid. 
