Dust on the Moon poses a threat to future lunar missions because it could engulf astronauts’ rovers as they trundle about the surface, astronomers were warned this week.
Several robotic probes are set to be sent to the Moon over the next few years. Experiments suggest that the dust, which is abrasive, sticky and unhealthy to breathe, will be a particular problem for them around the long-lasting periods of sunrise and sunset.
The warning, given at the RAS National Astronomy Meeting at St Andrews, Scotland, came as NASA called for commercial space companies to work with them in planning Moon missions.
They issued what is formally called a Request for Information to help agency officials better understand industries’ interests in developing a robotic lander.
The dangers of dust were a reminder of fears raised in the years before the Apollo landings, though on a different level. In the Sixties, before Neil Armstrong took his “one small step”, some thought he might exit his lunar module to sink deep into a layer of dust.
Those worries proved ill-founded. But now an Anglo-French team of scientists has modelled what they think will happen when future rovers run about on the lunar surface.
The team, led by Professor Farideh Honary of the UK’s University of Lancaster, found that there is a serious risk that rovers that move around sunrise and sunset could be engulfed in dust.
They worked with data produced from a series of missions sent to the Moon. They included the robotic landings such as NASA’s Surveyor and the Soviet Luna, plus the Apollo manned missions.
Those first astronauts to land on the Moon found that lunar dust stuck to their spacesuits and equipment which could be fatal if it blocked air passages in life-support systems. (The dust was also said to smell like gunpowder, but that is another story).
Professor Honary, in a joint study with ONERA in France, carried out simulations for two different lunar regions, the boundary between night and day (called the terminator) where the sun would either be rising or setting, and the region experiencing full daylight.
In both the test cases, dust particles travel upwards above the height of the rover. The results suggest that something like a rover might collect a significant quantity of dust over time due to electrostatic forces and that this would happen more quickly around sunrise and sunset.
Prof. Honary believes this has implications for rover design. She said: “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. Engineers really do need to think about this – one solution might be to build a dome-shaped rover so the dust simply falls to the ground.”