What will future lunar bases look like? NASA鈥檚 Lunar Architecture Team is looking for the answer 鈥� the design must be able to weather a rocket launch and the brutalities of life on the Moon.
The team is now weighing several options: an inflatable home that could be packed for launch and then inflated on the Moon鈥檚 surface using oxygen transported in tanks, a rigid structure, or a combination of both. NASA is expected to make a public announcement about the group鈥檚 work within the next few weeks.
Astronauts could be back on the Moon in 2020. Initially they won鈥檛 stay for more than a week, but the agency鈥檚 ultimate goal is to have them spend six-month stints on the Moon.
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There, temperatures range from -233掳 up to 123掳 Celsius and radiation constantly barrages the surface. Without a thick atmosphere to slow them down, as on Earth, micrometeorites slam into the Moon at speeds of up to 100,000 kilometres per hour, producing abrasive dust called regolith that can do serious damage to anything or anyone, says Andy Thomas, an astronaut who heads the agency鈥檚 Lunar Architecture Team.
A lunar habitat must be able to withstand those conditions and protect the astronauts inside.
Lunar accordions
Inflatable structures, made of flexible but tough materials such as Kevlar, would be relatively easy to bring up to the Moon because of their light weight. A demo of one such habitat was built by US-based ILC Dover and has a main chamber that spans 3.7 metres and a total volume of 53 cubic metres (see image at right).
But tests suggest a similar structure would need to be twice as big to accommodate the four-person crews planned to make the first lunar 鈥榗ampsites鈥�, says Karen Whitley, who leads NASA鈥檚 Inflatable Structures Project.
What may be more likely is a habitat that uses inflatable structures as tunnels between sturdier crew quarters. One possibility consists of two hard half shells joined by an inflatable midsection that could expand like an accordion, Thomas told New 杏吧原创.
But any type of structure would need to be made of layers that could withstand different types of dangers on the Moon, Whitley told New 杏吧原创. She says that combined, these layers could be up to 30 centimetres thick.
A light and highly reflective foil such as Mylar, Kapton or Teflon could guard against temperature swings, as could regolith heaped onto the habitat, which could also provide protection from galactic cosmic radiation and micrometeorites.
Layer of water
All that鈥檚 needed to shield astronauts from deadly onslaughts of high-energy protons spewed from the Sun during solar flares, Thomas says, is a 5-centimetre layer of water. This could be integrated into an inflatable structure using a bladder-like layer filled with water, sandwiched into a rigid structure, or simply stacked on top of the habitat in tanks.
Used packing materials and other waste could be piled against the structure to provide even more protection. Meteorites larger than dust-sized grains could be deflected by aluminium or Kevlar shields like those used on the International Space Station.
But lunar architects will need to develop more than just bases. 鈥淵ou鈥檝e got to have a lander that delivers the habitable units. You need some way of moving these things around on the surface. You need power in order to do that. You need communication systems and navigation systems, and you need crew,鈥� Thomas says.
He says NASA should have a complete design for a lunar habitat by 2015. That will allow time for prototypes to be tested in a vacuum chamber before astronauts head back to the Moon, and a home away from their homes on Earth.
