Water-prospecting Polaris lunar rover prototype built
By David Szondy
October 8, 2012
Astrobotic Technology Inc., a spin-off company of Carnegie Mellon University (CMU), has debuted its full-size flight prototype of its Polaris lunar water-prospecting robot. Polaris is specially designed to work in the permanently shadowed craters at the Moon’s poles. Scheduled to be sent to the Moon using a SpaceX Falcon 9 launch vehicle, the solar-powered rover is a contender in the US$20 million Google Lunar X Prize and is tasked with seeking ice deposits that could be used by future colonists.
Serious talk about setting up outposts on the Moon has been bouncing around since the 1940s, but has always come up against the major obstacle of water. With shipping costs to the Moon so high that they make Yeti steaks look economical, the only way that a lunar colony has any chance of success is if there is water already on the Moon. With water, a colony could grow crops, generate air and even make fuel for visiting spaceships. Without it, any stay on the Moon must be a short one.
Given that the satellite is a dry, airless rock with a daytime temperature of hundreds of degrees, this made dreams of permanent moonbases pure fantasy until recent NASA and Indian orbital probes detected possible water deposits at the lunar poles. The ice is there because some of the craters are perpetually in shadow, which keeps it from boiling away.
Unfortunately, this also makes prospecting difficult. The shadows and the high lunar latitude make it hard to use solar power for rovers. Also, the terrain is extremely rugged. Other missions can adapt their objectives to suit areas where a lander can operate, but on the Moon, it’s a matter of going where the ice is.
Astrobotic’s answer is Polaris. Designed to operate at the lunar poles, it is purpose built for prospecting. "It is the first rover developed specifically for drilling lunar ice," said William "Red" Whittaker, Astrobotic CEO and founder of the Field Robotics Center at CMU's Robotics Institute. Referring to other robots built by the center to study drilling on the Moon, Whittaker added, "what Polaris does is bring those many ideas together into a rover configuration that is capable of going to the moon to find ice."
Polaris is five and a half feet (1.67 m) high, seven feet (2.13 m) wide, about eight feet (2.43 m) long and weighs 150 pounds (68.03 kg). In addition to its own weight, it can carry another 150 pounds as well as the weight of a drill. With its two-foot (60.96 cm) composite wheels and special suspension, it can travel over rough terrain at about one foot (30.48 cm) per second. It’s built of lightweight alloys and composites chosen because they don’t give off gases that might contaminate samples. Weight is particularly important because of the size of the drill.
One tricky bit for Polaris is keeping it powered. The rover is solar powered, which is a problem because the ice it’s looking for is in the shadows of craters. Even under the best conditions, the sun hangs very low in the sky at the poles, so Polaris’ three solar arrays need to be very large and arranged vertically to catch enough light to generate 250 watts of power.
To help with the task, Polaris also uses software originally written for CMU's Hyperion robot that will allow the robot to keep track of its position and make sure it catches enough sun while using the available energy with maximum efficiency.
In the next months, Astrobotic will test and improve Polaris’ vision, navigation and planning software. The flight date for Polaris has not been announced, but once arriving on the Moon, the rover will spend ten days traveling three miles (4.82 km) and drilling ten to 100 holes in the lunar surface. If Polaris manages to survive the 14-day lunar night, the mission could be extended indefinitely.
Source: Carnegie Mellon University