News in Science

Kamikaze moon probe to carry out risky manoeuvre

Winding down Scientists have no delusions about the fate of NASA's LADEE robotic probe, which has been exploring the shroud of dust and the trace gases that surround the Moon.

On April 21, if not sooner, the Lunar Atmosphere and Dust Environment Explorer will crash into the surface of the Moon and vaporise.

But before its demise, scientists hope to break new ground by flying LADEE literally just above the ground.

"There is a chance that we could clip a mountain accidentally, but the risk is pretty low for that. And really, the value of the science that we can do with this attempt is worth this risk," says project manager Butler Hine, with NASA's Ames Research Center in Moffett Field.

"The prime mission is in the bag," adds LADEE program executive Joan Salute, with NASA Headquarters in Washington DC. "We wouldn't have authorised these low-altitude, high-risk attempts if all the requirements had not already been met."

Beginning this weekend, LADEE will begin dropping its altitude until it ends up less than 3 kilometres above the lunar surface.

Ramming into a lunar mountain isn't the only danger ahead. LADEE faces a prolonged period of potentially deadly cold during an eclipse on 15 April.

Engineers warn the spacecraft's propulsion system could freeze and burst, though current predictions indicate LADEE will survive.

"We'll see what happens," says Elphic.

If LADEE lives to die another day, scientists stand to gain far more detail about how much dust is blasting off the lunar surface at low altitudes.

They also want to get more measurements of trace gases, including neon, magnesium, aluminium, titanium and oxygen, which have been found in the Moon's so-called exosphere — the region of space around the Moon.

"Every time we dropped down to a lower altitude in the past, we've discovered something new," says Elphic.

In addition to better understanding the Moon, the data will be used to model the environments around other airless bodies, including the ice dwarf planet Pluto, which will be visited for the first time by a NASA spacecraft next year.