Wednesday, April 23, 2014

Asteroid Origins Satellite (AOSAT I): Landing on asteroids is one of the biggest challenges of our time

ASU researchers build their own "patch of asteroid" inside of a small spinning satellite seen here in this artist rendering. 

Credit: Sean Amidan 

A dozen astronauts have walked on the moon, and several rovers have been piloted on Mars, giving us a good understanding of these off-world environments.

But when it comes to asteroids, scientists enter uncharted territory.

Landing on an asteroid is notoriously difficult.

Asteroids have very little gravity because they have very little mass. Most of them appear to be rubble piles held together loosely, with surfaces covered in boulders and gravels and fine materials, much like the moon, but with a lot more cohesion.

On an asteroid, a rock the size of a bank building weighs as much as a cricket on Earth, making an astronaut like a superman. But what would you anchor to, what you would land on and how would you move around?

Because scientists and engineers don't know the most basic mechanical properties of an asteroid, sending a billion dollar landing mission to an asteroid is risky, and even likely to fail, until some preliminary investigations are conducted, requiring years of lead time.

A team at Arizona State University is looking to mitigate that risk and improve that schedule by building its own "patch of asteroid" inside of a small, spinning satellite costing less than $100,000.

The project is called the Asteroid Origins Satellite (AOSAT I).

"Landing on asteroids is one of the biggest challenges of our time," roboticist Jekan Thanga said.

Thanga, an assistant professor in the School of Earth and Space Exploration at ASU, is the engineering principal investigator for AOSAT I. "And space agencies worldwide, including NASA, are very focused on meeting that challenge."

Erik Asphaug, a planetary scientist and professor at ASU, is the science principal investigator for AOSAT I.

He and Thanga plan on launching a miniature satellite later this year that will serve as the world's first CubeSat microgravity laboratory.

A CubeSat is a modular small satellite with a 10-by-10 centimeter base and various unit lengths.

AOSAT I will be a 3U configuration, about the size of a loaf of bread, with two spun-up laboratories in the outer units, each housing a patch of real asteroid surface material.

In the first flight, one chamber will be filled to a depth of a few centimeters with very fine material representative of interstellar dust, or the fine "ponds" seen on several asteroids.

The second chamber, otherwise identical, will be filled with bits of shock-fragmented chondrite meteorite material.

Once launched into space and freely orbiting, these rocks will just tumble around – itself an interesting experiment.

But to build a realistic regolith surface for scientists to explore, the satellite is spun, to create microgravity-like conditions.

"We're taking asteroid material that landed on Earth and sending it back into space," Asphaug said. "It's a low-cost laboratory that really physically builds a patch of asteroid. It'll be asteroid gravity. It'll be made of asteroid stuff. We can do all sorts of experiments."

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