NASA launched LADEE (pronounced laddy), the Lunar Atmosphere and Dust Environment Explorer, Friday night at 11:27 p.m. ET. It launched from Virginia’s Wallops Island launching facility, and the site could be seen from a large area of the Eastern Seaboard. It will study the moon’s water cycle and dusty atmosphere for six months before concluding its mission.
When we think of the Earth’s moon, we generally don’t think of it in connection with the words “water” and “atmosphere,” having been taught from our early lives on that the moon has neither — but, the reality is that it has both, though the water that isn’t in the form of ice is likely deep within the moon, and the atmosphere is extremely thin.
The NASA mission will cost $280 million, which is cheap, by space exploration standards. One of the phenomena that LADEE will investigate are the “streamers” of light on the moon’s horizon that were first noted in 1968 by NASA’s Surveyor 7 mission.
A theory of scientists is that the moondust, possibly the result of asteroids and meteorites that have collided into the moon over millions of years, might have something to do with both the atmosphere of the moon and ice on areas of the moon’s surface, like inside of craters.
What is an “exosphere”?
The atmosphere of the moon is often referred to as an exosphere, a far more common type of atmosphere than the one on the Earth. Planets like Mercury and some moons and large asteroids have thin atmospheres, or exospheres.
In the words of the LADEE program scientist at NASA Headquarters, the moon really does have an atmosphere, but it’s so thin that “the individual molecules that make up the atmosphere are so few and far between that they don’t interact with each other, they never collide.”
That’s what exospheres are, in a nutshell: “collision-less atmospheres.”
First, LADEE will spend the next month orbiting the Earth three times. Then, when the third orbit’s high point is reached, after LADEE fires its rocket, it will be close enough to the moon that it will be captured by the moon’s gravity.
LADEE will orbit the Earth for one month while NASA technicians and scientist make sure its instruments are calibrated correctly, its laser communications system is tested.
The communications system weighs less than a radio system would, uses just a fourth of the power. It can beam data quicker, also, at over 600megabits every second.
The next phase will be for LADEE to drop down lower, around 12-37 miles over the surface of the lunar surface. It will stay there for three months to collect data on the dust in the moon’s atmosphere and the lunar environment.
Something lifts up the dust from the moon’s surface and transports it here and there, and scientists would like to learn what moves the dust around.
There are a few facts known about the dust, according to LADEE’s project manager, Butler Hines:
Dust is a very difficult environment to deal with on the moon. It’s not like terrestrial dust.”
Hines continued, comparing and contrasting moondust with dust on the Earth:
Terrestrial dust is like talcum powder. On the moon, it’s very rough, and it can actually follow electric field lines, it works its way into equipment. So one of the questions about dust on the moon is an engineering question: how do you design things so they can survive the dust environment?”
If electronic equipment can be designed to not be affected by moondust, it would likely be better able to withstand the surfaces of other planets NASA might explore in the future.
Instead of having wing-like solar panels, as many satellites have, LADEE possesses solar cells lining its entire body. These cells mean that its latitude won’t be affected by the sun, it won’t have to constantly reorient itself to maintain its power.
The University of Colorado’s Lunar Dust Experiment will be to analyze individual dust grains LADEE will collect while in a low orbit around the moon.
Atmospheric chemical variations in the exosphere will be analyzed, by NASA’s Neutral Mass Spectrometer, and it will analyze what makes up the moon’s atmosphere, and suspended dust particles will be checked out and investigated.
How long will LADEE’s mission last?
The length of the mission is limited to the amount of fuel available to LADEE, but NASA scientist believe the mission will last approximately 100 days.
Hine calls the moon’s gravitational field “ragged.”
The science phase of the mission is expected to last about 100 days, based on how long the spacecraft’s fuel holds out.
According to Hines:
…he total mission length is six months. We take about a month to get to the moon, we take another month to do the commissioning phase of the instruments and the laser communications experiment. Then we drop down (to the science orbit).
“The moon has a very lumpy gravity field. What that means is you never get truly circular orbits around the moon and the closer you get to the moon, the more your orbit varies up and down. And so to stay that low above the lunar surface we expend a lot of fuel.”
After the amount of fuels gets too low for LADEE to maintain its orbit, NASA scientist will crash land it into the moon’s surface.
When the fuel finally gets too low to maintain the spacecraft’s orbit, flight controllers will uplink commands to crash LADEE into the surface of the moon.
Often, we think of the Earth’s dust as being minor and insignificant. The Moon’s dust is, on the other hand, potentially very useful, and analyzing it, the water and the atmosphere of the moon, will teach us much more about our solitary satellite.
Written by: Douglas Cobb