HUNTSVILLE, Alabama - Imagine trying to land an unmanned space probe on an airless body such as an asteroid in deep space. You can't parachute - there's no air - and you can't beam commands from Earth. It's too far away. Your lander could crash before the command to "slow engines" got there.
A Huntsville team of engineers and technicians, including some just out of college, has been working on this problem for nearly two years at NASA's Marshall Space Flight Center.
Along the way, they've broken the NASA mold of long project life cycles, and they've formed alliances that might seem unlikely at first. Army technicians at Redstone Arsenal's test range, for example, are a key part of the team, and Huntsville's Google Lunar X Prize team has compared notes as it races to build its own smaller lunar lander.
The team's prototype lander, affectionately known as "MightyEagle," has successfully hovered as high as 16 feet and lowered itself safely to the surface of its test building.
After proving through more than 160 flight tests that the lander's innovative pulsed thrusters do work, team leader Julie Bassler, test director Larry Hill and their cadre take MightyEagle outside in August for blue-sky flying.
You don't do that until you're pretty sure your lander won't careen into something or disappear over the horizon.
And you don't do any flying, indoor or out, until you've mastered the engineering challenge of Earth's gravity. When the goal is a lander that works where there is no air and little or no gravity, the team needed to put an "Earth gravity canceling thruster" on MightEagle early on.
If the outdoor tests work, Bassler said last week, "We're ready to go to flight design and send something to the moon or any other airless body. You could send it to a near-Earth asteroid or a Martian moon like Phobos."
Another target might be Earth's own moon. Scientists already want to position several probes for long-term studies of lunar surface tremors, among other things.
Missions like that are why small, lightweight and inexpensive landers are very popular in the space world today. They can go where humans can't, cheaply, and stay for months or even years taking and testing samples.
"There's not one that can do what this one can do," Marshall spokeswoman Kim Newton said last week of the known competitors.
Previous unmanned probes have used parachutes and air bags for safe, if bouncy, landings, but Marshall's is the first with pulsing thrusters.
The test lander is fueled by an environmentally friendly propellant that's 90 percent hydrogen peroxide. A real space lander would use a much different fuel blend.
MightyEagle has a closed power system requiring no human controllers, so its eventual successors will be able to make their way to the surface using feedback from their own sensors.
"Big science in a very small, very smart package," Bassler says. "That's our goal."
MightyEagle looks impressive hovering above its test building floor, but the team putting it together is almost as impressive.
Bassler, an aerospace engineer who grew up on an Illinois dairy farm, is leader. She led engineers at NASA's Johnson Space Center in Houston in the International Space Station Program Office for three years before transferring to Marshall. Here, she's been a supervisor in the Lunar Precursor Robotic Office on successful lunar missions including NASA's Lunar Reconnaissance Orbiter and Lunar Crater Observation Sensing Satellite.
About two dozen people are working with Bassler and Hill on what is officially known as the Robotic Lunar Lander Development Project. The young engineers and technicians on board saw their work go from drawing board to flight testing in 17 months.
The pace extends to the testing cycle, too, although Bassler's team isn't skimping on those. The outside flights will be the fourth test series.
"During testing, we're running through an actual mission-sequence scenario," Bassler said, "training a team capable of building and executing an actual lunar mission in less than two years if we got the go-ahead today."