Aviation Week & Space Technology, 09/17/2007, page 32

Frank Morring, Jr., Washington

Industry may be tapped for rad-hard pressurized human Moon rovers

The latest wrinkle in NASAs plans for human exploration of the Moon could give industry a chance to set up a private lunar-surface bus line, provided the coaches are pressurized against vacuum and hardened against space radiation.

Agency experts will begin shopping around new refinements in the evolving human exploration architecture at a conference in Long Beach, Calif., this week, seeking comments and potential partners. Those could include commercial companies as well as the international partners already looking for niches in NASAs ambitious lunar plans.

Administrator Michael Griffin has given his OK to the latest updates to NASAs lunar-surface architecturethe set of broad concepts that will drive development of hardware that human explorers will use in the decade after 2020, according to Doug Cooke, deputy associate administrator for exploration systems.

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One new lunar-rover concept would have the crews spacesuits docked to the back of the cabin for simplicity and ease of donning. In a pinch the vehicle could carry four astronauts.

Credit: NASA CONCEPT

"Weve drilled down on the concepts to get a more detailed understanding of performance and capabilities," Cooke told the Space Transportation Assn. on Sept. 11.

Building on six different lunar architecture options, exploration planners have moved beyond the idea of building up a base at one of the Moons poles with a succession of relatively small lunar landers, to early delivery of about three larger habitats.

That would reduce the "boneyard" of discarded landers at the polar moonbase, says Geoffrey Yoder, lunar architecture team lead at NASA headquarters. It also would provide surface explorers with greater flexibility to meet the needs of scientists by getting away from the polar base for extended periods of time. Planetary scientists may want to send humans to examine a lunar surface feature in detail, or to deploy outward-looking instruments away from the dust and radio noise of the main base (see p. 91).

"If you had one of those modules that was on a mobility system thats robotically controlled, we could send it robotically, say, 1,000 km. to another site of interest, and then send a crew to that site," Yoder says. "Thats what we call a super sortie." Details of just how far from the polar base human explorers might need to go will be worked out in coordination with scientists over the coming years. In extreme cases, a crew could fly directly to a remote outpost directly from Earth, stay in the pre-positioned hab long enough to complete its science investigation, and then return to Earth while the hab moves on to another site.

For shorter sorties, the refined concepts call for lunar explorers to set out in pressurized long-distance rovers shieldedperhaps with a few centimeters of wateragainst the galactic cosmic radiation that makes extravehicular activity (EVA) in spacesuits dangerous to human health in the long run. The contemplated water jackets would also provide protection from more dangerous solar flares.

For safety, four-member lunar-surface teams would take two "fairly small" pressurized rovers that normally would carry only two astronauts but in a pinch could carry all four members of a surface team for self-rescue.

"With two rovers we could actually send them out farther than walk-back distance, which has always been kind of a requirement when you had a rover," Cooke says. "And that limits your range significantly. So we came up with an approach that we think we could live with, where you have two of these and they go long distances."

The current concept calls for step-in suits docked to the outside of the rovers. "We wouldnt have an airlock," Cooke says. "The suits themselves dock with the pressurized compartment, and the crew can open up the backpack from inside the pressurized rover and climb in the suit from the back side. So the suit stays outside all the time, and the crew climbs in."

Also under study is the feasibility of fitting the rovers with plug-in appliances, such as backhoes or robotic arms, and perhaps having them dock directly to the pressurized habitats of the lunar base.

"This is an idea where we can actually get EVA crew out quick, so you can go to the different sites, get them in the suits, get them out on the surface, get them working and get the efficiency factors up on crew time," Cooke says.

Inflatable structures remain a possibility for habitats, Cooke says, although no final decisions have been made. Both Johnson Space Center and the Jet Propulsion Laboratory have made prototypes of the robotic mobility systems that would move around the habitat modules.

Yoder says his team will continue to evaluate what actually will be utilized on the lunar surface, and how to meet those needs. The duration of a sortie is still at the "several-day" level of definition, and the final requirements will determine the power source the rovers will use. For a drive of 100 km., which would take a couple of days, battery power may be adequate. Longer distances probably would call for fuel cells, he says.

Cooke says the hardware that would be needed for the architecture refinements could be built by NASAs international partners or commercial companies. To that end, the agency will brief its concepts in detail at upcoming conferences in the U.S. and abroad, starting with the American Institute of Aeronautics and Astronautics Space 2007 conference in Long Beach Sept. 18-20.

All of the new concepts "seemed to us a very good way of maximizing the crews abilities once we get them there," Cooke says. "We spend a lot of money to get them there. We want to make them as effective as we can."