There are so many planets, asteroids, and other celestial bodies to explore in space and most of them don’t have the same gravity as Earth. Functioning in these microgravity environments bring their own set of challenges. NASA is currently working on a novel solution to this problem.
Planetary moons, comets and asteroids – all are on NASA’s list of objects to explore – are less than ideal environments to deploy robots like the Mars Curiosity rover or even landers like the European Space Agency’s Philae.
Philae, which landed on the surface of Comet 67P/Churyumov-Gerasimenko as part of the Rosetta mission earlier this year, attempted to use a harpoon to maintain its surface position on the comet but the harpoon failed and the lander bounced back into space. Although Philae eventually landed, the harpoon solution was less than ideal.
NASA is designing a next-generation robot to explore the microgravity environments found on these smaller celestial bodies. Instead of wheeled or legged, the robot will move by tumbling and rolling. This form of locomotion, NASA is convinced, will make it easier to explore microgravity bodies. Dubbed the hedgehog, the robot uses internal flywheels to propel the robot by tumbling, rolling and hopping.
A team from NASA’s Jet Propulsion Laboratory (JPL) has teamed up with scientists from Stanford University, also in California, and researchers from the Massachusetts’s Institute of Technology (MIT) to develop the technology. In a news release, Issa Nesnas, JPL team leader, said:
Hedgehog is a different kind of robot that would hop and tumble on the surface instead of rolling on wheels. It is shaped like a cube and can operate no matter which side it lands on.
There are currently two versions of the Hedgehog, one without external legs that looks like a cube and another with spikes on the surface. These spikes act as legs for the Hedgehog, allowing it even more options for movement. These spikes also act as probes to sample the surface the robot is currently on. Benjamin Hockman, lead project engineer at Stanford University, said:
The geometry of the Hedgehog spikes has a great influence on its hopping trajectory. We have experimented with several spike configurations and found that a cube shape provides the best hopping performance. The cube structure is also easier to manufacture and package within a spacecraft.
In addition to being more mobile, the Hedgehog also has the advantage of being less expensive to build and deploy. For the same cost as one Curiosity, NASA can build multiple Hedgehogs and, by deploying them in different places, explore more of the object.
Hedgehog is controlled remotely, from a mother ship, using the same technology that controls Curiosity. NASA is working on increasing the autonomy of the exploring robots.