Exploring the Moon with robot spacecraft may not seem as exciting as an astronaut—a la Apollo 14’s Alan Shepard—whacking a golf ball along a dusty lunar fairway, but considering the budget woes of the National Aeronautics and Space Administration, something, anything, which returns a human presence to our nearest neighbor in space is a step in the right direction.
Back to the Moon
In the case of the space agency’s Lunar Atmosphere and Dust Environment Explorer spacecraft, LADEE for short, good things come in small packages.
NASA expects the solar-powered LADEE, which is slightly more than half the length of a VW Beetle, to arrive in lunar orbit this week to study the Moon’s barely-there atmosphere. The spacecraft will also remotely search for suspended dust particles and check out a purported atmospheric glow—a phenomenon sketched by an Apollo 17 astronaut during the last crewed flight to the barren lunar landscape.
Since the last humans to walk on the Moon retreated back to their terrestrial cradle in 1972, only a handful of unmanned spacecraft have returned there. And frankly, by the time Apollo 17’s lunar module “Challenger” blasted off from the rugged Taurus-Littrow Valley landing site, Earth’s companion in space had already lost much of the romance it had acquired in pre-Apollo days.
But that may not be all bad because much like an enduring marriage that transitions from a starry eyed honeymoon phase to a more mature and lasting companionship phase, so too is humanity’s scientific relationship with the Moon. Yes, the honeymoon may be over, but the relationship is becoming deeper, richer.
LADEE, launched in September from NASA’s Wallops Island facility in Virginia, is going boldly where no lunar mission has gone before.
Modular Spacecraft Design
Managed by a small staff at the Ames Research Center in California, LADEE is a mission on the threshold of change; it’s both a traditional and revolutionary effort for NASA.
LADEE is part of the U.S. space agency’s new Modular Common Spacecraft Bus design concept, an innovative way of getting away from costly, custom-built unmanned spacecraft and moving to an assembly line mix-and-match design.
Since LADEE uses the new common bus, we’ll see many variations of this spacecraft in the future, such as orbital and flyby probes—for low-earth work, lunar studies, and asteroid research—plus mini-robot landers.
LADEE’s Mission: 100 Days Around the Moon
Once safely inserted into a 20 km (12 miles) by 60 km (37 miles) orbit around the Moon’s equator, LADEE’s science mission is expected to last 100 days.
During its multi-month run, LADEE’s instruments will study the lunar exosphere and dust. LADEE’s compact, onboard instruments include a dust detector, a neutral mass spectrometer (based on the Mars Curiosity’s mass spectrometer), and an ultraviolet-visible spectrometer, according to NASA online reports by LADEE Project Manager Butler Hine. The spacecraft will also serve as a test platform for a laser communications terminal or lasercom.
Moon’s Ultra-Thin Atmosphere
The Moon’s atmosphere, which exists in the near-vacuum of space, has an estimated total mass of less than 10 metric tons, with a scant surface pressure of 3×10−15 atm (0.3 nPa).
For comparison, at sea level, our atmosphere has 100 billion billion molecules per cubic centimeter of air. The Moon’s atmosphere has only 100,000 to possibly 10 million molecules per cubic centimeter.
The ghostly lunar atmosphere appears to be replenished by both internal outgassing (from the radioactive decay of uranium and thorium) and external sputtering.
Sputtering occurs when energetic solar particles collide with a planet’s surface and stirs up trace elements—such as sodium and potassium, in the case of the Moon.
If all goes well, NASA’s LADEE mission should help planetary scientists peel back, just a wee bit more, the Moon’s alluring veil of mystery.
Hoekzema, N.M. An Atmosphere for the Moon. (2009). Max-Planck-Institute for Solar System Research. Accessed October 4, 2013.
Rowe, Aaron. Exclusive Video: Meet the Spacecraft that Could Save NASA a Fortune. (2008). Wired. Accessed October 4, 2013.