Dust hazard for Moon missions

Full moon is seen in the sky near Liverpool, England Paris - Arab Today A return to the Moon could be hampered by dust, a poorly-understood threat to machines and people alike, according to a presentation at a space conference that ended Friday. Simulations by scientists in Britain and France show that in key zones of Earth's satellite, dust kicked up by a landing or exploration gains an electrostatic force that briefly overcomes lunar gravity, it heard. As a result, the dust lingers high above the surface, presenting a thin grey cloud of fine, sticky, abrasive particles that hamper visibility, coat solar panels and threaten moving parts, they said. Some kinds of lunar dust are laden with iron, presenting a toxicity risk for humans if breathed in, they said. Farideh Honary, a professor at the University of Lancaster, northwestern England, said lunar dust was already identified as a potential hazard by returning Apollo astronauts. But only now, with mounting interest in a return to the Moon, were scientists taking a closer look, she told AFP. "We need to study the dust in much more detail and to do more measurements before (sending) manned missions," she said by phone. In a computer simulation presented at the annual conference in Edinburgh of Britain's Royal Astronomical Society (RAS), Honary said dust did not behave uniformly around the Moon. What makes the dust levitate and cling is a force caused by electrostatic charge. Exposure to ultraviolet rays in sunlight drives out electrons and gives the dust a positive charge. But at night-time or in shadow, the torrent of particles spewed out from the Sun charges the dust with electrons, giving it a negative charge. The dust movement occurs most in areas where the Sun is either rising or setting, and dust particles of opposite charges that are disturbed get pulled towards each other, floating in a haze. "On most of the lunar surface, a rover would experience roughly 14 days of sunlight followed by 14 days of darkness, so the transition between the two would last a long time by terrestrial standards," said Honary. "Engineers really do need to think about this," she said. Building a "dome-shaped" rover from which the dust slides, as opposed to a rover that is box-shaped or has lots of crevices or surfaces on which the dust could fall, would be a good option, she said. The last manned mission to the Moon was Apollo 17, in 1972. China has said it will attempt to land an exploratory craft on the Moon in the second half of 2013 and transmit back a survey of the lunar surface. According to the specialist website Dragon in Space, Chinese mission controllers are mulling five locations for a site where a six-wheeled rover will be deployed. Indian space officials have also sketched plans for sending a rover in 2015. Source: AFP