The LADEE mission seeks the faintest of lunar phenomena.
The LADEE spacecraft arrives at the Moon.
If all goes according to plan in the next few days, the latest NASA robotic mission to the Moon will enter lunar orbit. Launched last month from the Wallops Island site, LADEE (for Lunar Atmosphere and Dust Environment Explorer) will spend the next few months orbiting the Moon. This small spacecraft will attempt to characterize and measure the lunar “atmosphere,” while also looking for dust that might be electrostatically levitated above the surface or thrown into ballistic flight by impacts.
Wait a minute. Did I say “atmosphere?” Isn’t the Moon renowned for its lack of an atmosphere? Indeed it is. In fact, the 10-12 torr surface pressure of the Moon is a better vacuum than we can achieve with even the most advanced equipment in Earth laboratories. (For comparison, sea level pressure on the Earth is about 760 torr, making the lunar surface pressure over one hundred trillion times less dense.) A better term for the tenuous gas near the Moon is “exosphere,” meaning free flying gas molecules that may or may not be gravitationally bound to the Moon. In such an “atmosphere,” there ...