PORTLAND, Ore. ó Hopping robots aim to solve the problems associated with wheeled models like the Spirit rover, which today is mired in a Mars sand trap. If Spirit had been equipped with hopping capabilities, it could have just jumped back onto solid ground, according to NASA astronaut Jeffrey Hoffman, now a professor at the Massachusetts Institute of Technology.
Working with the Charles Stark Draper Laboratory, MIT is designing what it calls the Terrestrial Artificial Lunar and Reduced Gravity Simulator, or Talaris, as an entry for the Google Lunar X Prize. The competition's $30 million purse will go to the first privately funded team to send a robot to the moon that succeeds in traveling 500 meters and transmitting images and data back to Earth. The MIT-Draper team, Next Giant Leap, joins 20 other teams competing for the prize.
When fully assembled, Talaris will consist of the carbon fiber vehicle, four electric ducted fans to simulate lunar gravity, lithium polymer batteries to power the fans, compressed gas thrusters and nitrogen tanks to provide the fuel and thrust to maneuver the vehicle, and an avionics system to navigate it. (Graphic provided by160160hraim Lanford and Ryan McLinko, MIT)
MIT will present details on the project at the American Institute of Aeronautics and Astronautics Space 2010 conference, running Aug. 30-Sept. 2 in Anaheim, Calif.
The Mars rover has proved the value of a mobile robotic platform through its extensive exploration of the Mars surface within a few kilometers of the landing site. But hopping capability would allow exploration of an area several hundred kilometers from the lander, according to the Talaris developers.
"With a hopper, you simply hop in, collect data
and hop out," said Hoffman. "There are limits to the terrain you can
access on wheels."
The two-year-old program has already produced a scaled-down, 3-foot wide prototype to test the guidance, navigation and control software that would allow the hopper to explore unknown terrain autonomously. The propulsion system uses compressed nitrogen. Talaris, a squat, squarish platform on which sensors could be mounted, blasts the nitrogen to initiate hopping, then uses its control software to hover, move sideways and initiate a safe landing.
Downward-facing, electric ducted fans provide continuous "lift" to counter terrestrial gravity and enable Talaris to emulate its natural weight on other planetary bodies, thereby letting the robot be tested on Earth under conditions that simulate the atmosphere of the moon. The fans' speed can be adjusted to simulate gravity on other astronomical bodies, from asteroids to planets.
The main drawback of hoppers is that the supply of compressed nitrogen eventually runs out. While the researchers are hunting for ways to "reload" the compressor using renewable energy, such as solar cells, the hopping system may in practice be used only as alternative propulsion method, reserved for when a rover's wheels get stuck.
By the end of the year, the team hopes to demonstrate the 110-pound prototype hopping up to 20 meters at a time. A full-sized rover is slated to be ready for Google Lunar X-Prize entry in 2014. The team is working with spacecraft specialist Sierra Nevada Corp. (Sparks, Nev.) on a vehicle to take Talaris to the moon. Draper Lab is designing the final descent and safe landing systems.