The crash of NASA’s Morpheus lander was an unfortunate setback, but like any good space pioneer, the agency has more than one string to its bow - and more than one lander in the hanger. On August 8, NASA’s prototype “Mighty Eagle” autonomous lander carried out the latest in a series of flight tests at NASA's Marshall Space Flight Center in Huntsville, Alabama. Though smaller than Morpheus and much less powerful, the craft is being used to develop a new class of autonomous robotic landers to explore the airless bodies of the Solar System from the planet Mercury to the moons of Jupiter.
Mighty Eagle is a testbed for developing autonomous systems that could make landings on airless bodies, such as the Moon, where parachutes can’t be used. The last tests of Mighty Eagle were carried out in 2011. The current series is to conduct flight testing of improved autonomous guidance control systems. During the tests the lander will fly and hover at altitudes between 30 feet (9.14 m) and 100 feet (30.48 m) as well as traversing sideways and landing.
The chances of Mighty Eagle sharing the fate of Morpheus are remote. Where Morpheus was loaded with volatile fuel for its rocket engines, Mighty Eagle is a Warm Gas Test Article (WGTA). That means it uses 90 percent hydrogen peroxide as fuel. It’s the same system as that in James Bond rocket belts used at sporting events and other public exhibitions.
Mighty Eagle’s engines are, in fact, steam rockets. The hydrogen peroxide passes over a catalyst and breaks down into steam and oxygen, pushing the three-legged lander’s 700 pound (317.5 kg) into the air under command of its onboard computer. There’s not flame, so this is much safer for test purposes. It allows for much faster turnarounds between flights and simplifies engineering because hydrogen peroxide isn’t as corrosive as other fuels, so stainless steel can be used in the engines.
Because the waste products are water and oxygen, it’s also very green.
The previous version of Mighty Eagle, the Cold Gas Test Article (CGTA), used compressed air, which was even safer, but only allowed flights of a few seconds as opposed to Mighty Eagle’s several minutes.
Mighty Eagle isn’t a very large craft. Standing 4 feet (1.21 m) tall and 8 feet (2.43 m) in diameter, it’s only about the size of a golf cart. However, it is able to carry out a complete flight from liftoff to landing with its computer controlling its thrusters and the cameras processing live video feeds for autonomous navigation.
Airless bodies of the Solar System that could be explored using this technology include our own Moon, Mercury, the asteroids and the moons of the outer planets.
Prospective missions include a lunar polar landing to look for the presence of water, carbon dioxide, methane and ammonia in the ever-shadowed craters there; scouting sites for future manned landings; studying the far side of the Moon and conducting sample return missions.
The current series of tests will continue through September.
The video below shows Mighty Eagle's flight test.