It's carrying four different scientific instruments, three to measures things about the lunar exosphere -- that's an atmosphere that is so thin that the molecules don't bounce off of each other -- and one laser communication test project. The first three are the Lunar Dust Experiment (LDEX), a Neutral Mass Spectrometer (NMS), and an Ultraviolet and Visible Spectrometer (UVS) while the latter is called the Lunar Laser Communications Demonstration (LLCD) and might be the first step towards space Internet!
And why are we sending it?
Because sending stuff to the moon is super cool. And modular spacecrafts could be a more cost efficient way for us to explore space. NASA Ames Director S. Pete Worden compares it to the way you can swap out pieces in a desktop computer.
OK, but why these specific instruments
There are some ongoing mysteries about the lunar atmosphere that weren't answered by the Apollo missions. Firstly, there was this weird glow across the horizon described by astronauts, that some scientists hypothesize is dust. But the moon's exosphere shouldn't have enough molecules bouncing around to hold up dust. Rick Elphic, the LADEE project scientist, says it would be an "exotic new phenomenon" if it is dust.
So LDEX is device that is going to scoop up bits of whatever dust LADEE might fly past while in orbit around the moon and measure it. The NMS will do sort of the same thing, only with gases in the lunar atmosphere. We know argon and helium are there from previous missions, but this will also help look for other things -- like water if it's there.
The UVS has a dual purpose -- it can look for emission lines from gas in the atmosphere and for light scattered by dust in the atmosphere. Elphic sees these tests as an opportunity to address two mysteries: "What is the atmosphere made of?" And "does the dust behave this way?" On that latter point, he's confident they "have the instrumentation to answer that question once and for all."
All three of these tests in combination will help scientists get a better grasp on how exospheres work. That's important because exospheres are actually pretty common, and if we continue exploring the universe humans will run into them in other places -- from Mercury to objects on the very farthest fringes of our the galaxy.
Didn't you say something about space Internet earlier?
Yeah, that's important too! That's the LLCD. It should be able to send 622 megabits per second to the ground from the moon. That's like sending 100 compressed HD channels at once. Matching ground sites should be able to send 20 megabits per second up to the moon.
Right now, spacecrafts use radio waves to communicate with the Earth. But radio waves are really spread out, and the telescopes that pick them up are huge -- like 100 yards in diameter. Lasers are much more concentrated you can use a series of much smaller optical telescopes to pick up the laser signal. And the data transfer rates for lasers communication should be way faster. Radio communication is "like having dial-up, and we're bringing broadband to space," explains Don Cornwall, the LLCD mission manager.
So how did the launch go?
Awesome! Here's NASA's video:
The whole launch was about a 20-minute process that started at 11:27pm ET Friday. The Minotaur V rocket launched LADEE in a five-stage process. The first three stages of the Minotaur V rocket lasted a little longer than 200 seconds, then were jettisoned off into the Atlantic Ocean.
The fourth stage was a Star 48BV engine that burned for around 85 seconds, inserting LADEE into a low Earth orbit. The fifth stage lasted another 60 or so seconds. Around five minutes after the fifth stage burnout, the payload separated. That's when the spacecraft activation and checkout occurred, approximately 23 minutes after launch.
What happens next?
Well, now LADEE is up in space! Which is great, but it's not at the moon yet. Before it gets there, it will do a couple of phasing orbits around the Earth before inserting itself into lunar orbit. The earliest LADEE is expected to arrive at the moon is Oct. 6, a month after launch. Then it will enter a 40-day commissioning phase at a high orbital altitude of around 200-300 kilometers. During this commissioning phase it will test out the the LLCD -- the space broadband! The other science tests will also be activated and receive basic checkouts.
Then the 100-day science phase will start with LADEE moving to a closer orbit of 20-150 kilometers from the moon. This is when all of the lunar atmospheric and environmental tests will begin, although the LLCD may also do some additional testing during this phase.
Sadly, at the end of the science phase and about 160 days after the initial launch, LADEE will enter the "decommissioning" phase. In this case, decommissioning phase means crashing into the Moon. But don't worry, LADEE will keep collecting data until the very end.