NASA launches innovative moon probe
Updated Sept. 7, 2013, 1:37 AM ET
Lighting up the night sky with a trail of fiery exhaust, an Orbital Sciences Minotaur 5 rocket blazed away from the Virginia coast late Friday, boosting a small NASA probe into an extreme elliptical orbit to set up a leisurely month-long flight to the moon.
The goal of the innovative mission is to study the moon's ultra-thin atmosphere and solve a long-standing mystery: how trace amounts of the pervasive dust that blankets the lunar surface get suspended above the surface, looking to Apollo astronauts like long streamers extending toward space.
The $280 million Lunar Atmosphere and Dust Environment Explorer, or LADEE, mission got off to a sky-lighting start 11:27 p.m. EDT (GMT-4) Friday when the first stage of its solid-fuel Minotaur 5 rocket ignited with a brilliant rush of flame.
Quickly climbing away from the Mid-Atlantic Regional Spaceport at NASA's Wallops Island Flight Facility, the Orbital Sciences Corp. rocket put on a dramatic show, spewing a long trail of white-hot exhaust as it accelerated away to the East.
The first three stages of the rocket were made up of "Peacekeeper" ICBM solid-fuel motors to boost the LADEE spacecraft out of the dense lower atmosphere. Because of U.S.-Russian treaty requirements, retired Peacekeeper hardware can only be launched from Alaska, California and Wallops Island.
All three Peacekeeper stages appeared to fire normally, boosting the spacecraft to an altitude of around 222 miles. After a short coast, a commercially developed Star 48BV motor ignited to continue the push to space.
After another coast, the fifth stage fired small thrusters to impart a stabilizing spin and the Star 37FM fifth-stage motor ignited about a minute later to put the LADEE spacecraft into a highly elliptical orbit. The goal was a low point, or perigee, of around 124 miles and a high point, or apogee, of more than 172,000 miles.
The LADEE spacecraft separated from the fifth stage about 24 minutes after liftoff, flying on its own for the remainder of the mission. Telemetry indicated the spacecraft was healthy and on course.
"Godspeed on your journey to the moon, LADEE," an engineer said over the flight control audio loop.
"It's a great day for NASA, for Orbital, for the country, to be quite honest," NASA Administrator Charles Bolden said a few minutes before liftoff. "It's a very important mission because we've never studied dust on the surface of the moon or, as thin as it is, the atmosphere of the moon.
"So this will give us a lot of information about the moon itself, but also some information about the structure of the solar system."
If all goes well, the spacecraft will use on-board thrusters to refine its trajectory during three-and-a-half trips around the Earth, putting the high point of the orbit close enough to the moon for lunar gravity to take over, pulling the spacecraft in. A major firing by LADEE's on-board rocket engine will complete the job.
Flight controllers plan to spend about a month checking out the spacecraft's systems, calibrating its instruments and testing an experimental laser communications system.
Assuming no problems crop up, the spacecraft will be commanded to drop down to an extremely low altitude, between 12 and 37 miles above the lunar surface, to begin a three-month mission to study the moon's tenuous, ultra-thin atmosphere and the dust that blankets the terrain and occasionally gets lofted above the surface.
"LADEE has two major science goals, the understand the lunar atmosphere as well as the dust environment around the moon," Sarah Noble, the LADEE program scientist at NASA Headquarters, said before launch. "I think sometimes we get a little surprised when we start talking about a lunar atmosphere because most of us were taught in school that the moon doesn't actually have an atmosphere.
"It does, but it's very, very thin. It's so thin, that the individual molecules that make up the atmosphere never see each other, they don't interact, they don't collide. This is something we call an exosphere."
As it turns out, Earth also has an exosphere, but it begins at a higher altitude than the International Space Station's orbit. On the moon, it begins at ground level.
"So the term we use for this class of atmosphere is a surface boundary exosphere," Noble said. "In fact, the moon is not the only example we have. Mercury, a lot of the moons of other planets as well as some of the larger asteroids in our solar system all have surface boundary exospheres. It turns out to be the most common class of atmosphere we have."
But little is known about the physics and chemistry of exospheres and "LADEE is a really great opportunity to learn, not only about the moon, but many, many bodies in our solar system," she said.
LADEE's instruments also will study dust suspended in the exosphere, a phenomenon first observed by robotic landers in the 1960s and later seen by Apollo astronauts from the surface of the moon.
The goal is to collect data that may help researchers figure out how dust and other constituents are lifted from the surface and transported from one point to another. From an engineering perspective, the data might help spacecraft designers better protect their hardware from dust intrusion.
"Dust is a very difficult environment to deal with on the moon. It's not like terrestrial dust," said Butler Hine, the LADEE project manager at NASA's Ames Research Center.
"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?"
The science phase of the mission is expected to last a little more than three months, based on the amount of fuel the small spacecraft can carry.
"The moon has a very lumpy gravity field," Hine said. "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."
When the fuel finally gets too low to maintain the science orbit, the spacecraft will be commanded to crash into the surface.
"We've studied the moon extensively since the Apollo astronauts last left 40 years ago," said John Grunsfeld, NASA's associate administrator for space science. "Since then, we've discovered the moon, in a sense, is still alive, it's still evolving. The LADEE mission is going to give us whole new vistas on our nearest neighbor."
