Universe Today : Tether to Keep Asteroid Explorers Grounded

Written by Fraser Cain

Here on Earth, gravity keeps us firmly on solid ground. But when astronauts set foot on some of the more exotic objects in the Solar System, just walking is going to be a struggle. In the microgravity of an asteroid, every step astronauts take will send him flying up in a long arc, and maybe out into space. It would be almost impossible to get around. Fortunately, MIT researchers have developed a tether system that could keep astronauts firmly anchored to the surface, but still let them walk around.

When humans first set foot on the Moon, they learned right away that the lower gravity was going to cause problems getting around. It took a few missions, but astronauts finally perfected a silly-looking hop that allowed them to skip around in the 1/6th gravity. But on an asteroid which can be only a few kilometres across, the wrong step could put an astronaut into orbit; the gravity's that low. As long as the asteroid is above 8 km or so, a wrong footed astronaut would eventually return to the surface, but it would make exploration infuriating.

What the MIT researchers have developed is a tether system that astronauts would attach to the surface of the asteroid. The ropes would be strung completely around the asteroid, sort of like putting a rubber band around a ball. Once the lightweight ropes were in place, they would apply pressure downward on the astronauts, giving them a sort of artificial gravity. The idea will be published in an upcoming issue of the journal Acta Astronautica.

Previous researchers have suggested that astronauts could bolt themselves to the surface of the asteroid, but that might not be possible. Researcher Ian Garrick-Bethell describes the flaw in that plan, "it would be like trying to bolt yourself to a pile of gravel or sand."

The team envisions a rocket that would fly around the asteroid, unraveling a spool of rope. Once the spacecraft completes an orbit of the asteroid, the loop is formed and then tightened.

Nobody still really knows what the surface of an asteroid will be like. Even this might now work, as the rope might cut into the surface of the asteroid and not be usable to hold an astronaut down. But at least they could use it as a handhold to drag themselves along without flying away.

Original Source: MIT News Release