By Paul Gabrielsen, Special to CNN
Editor's note: Paul Gabrielsen is a science writer based in Santa Cruz, California. He is a science communication graduate student at the University of California, Santa Cruz, and has written for ScienceNOW, the San Jose Mercury News, Geospace and mongabay.com.
In the future, scientists want to be able to send spacecraft to study asteroids such as the one that will approach the Earth on Friday. A concept for these landers may look familiar to anyone who grew up in the 1970s.
Egg-shaped and weighted at the bottom, the landers – prototype designs for a possible future NASA mission – look like roly-poly Weebles, which wobble, as the old jingle goes, but don’t fall down.
The craft are still only computer simulations, a decade away from being ready to launch, but their simple design overcomes some of the biggest challenges in exploring asteroids’ alien landscapes.
Planetary scientists Naor Movshovitz and Erik Asphaug designed the landers, which they call “pods.” NASA’s Near Earth Object Program funded their work, which grew out of Movshovitz’s doctoral research on deflecting asteroids from Earth’s orbit. Movshovitz is a doctoral student at the University of California, Santa Cruz; Asphaug, his advisor, recently moved to Arizona State University.
Whether attempting to deflect an asteroid or trying to land an astronaut on its surface, scientists need to know the basics of what its surface is like. Small, low-cost surface landers (less than $1 million, with no moving parts) can travel to an asteroid and provide the needed information, if they can land successfully.
Asteroids are tricky places to land a spacecraft right-side up. Spinning through space, an asteroid’s small, uneven terrain and extremely weak gravity make even the idea of “up” and “down” fluid concepts. The techniques that have safely landed the recent Mars rovers (bouncy airbags for Spirit and Opportunity, a complicated “sky crane” for Curiosity) simply don’t work on an asteroid.
“Asteroids being weird and wacky places, we have to be prepared for any situation,” Asphaug said.
Their first design was boxy, like a deck of playing cards with one side coated in bouncy-ball rubber. The idea was for these landers to bounce around the asteroid before coming to rest, nonbouncy side down.
Since asteroids are in short supply in Santa Cruz, California, the scientists tested their designs in a computer model, using a video game physics simulator. Video game physics are just as good as scientific physics models, Asphaug said, and modern graphics cards can run the simulations 100 times faster.
Movshovitz tossed the square landers onto a computer-simulated asteroid. The rubbery side bounced, as designed. But too many landers came to rest wrong-side down.
They developed a new design – an egg-shaped lander weighted on the bottom, just like the Weebles that Asphaug played with as a kid.
“I was fascinated by Weebles,” Asphaug said. The toys, first produced in 1971, could be knocked in any direction but would still come to rest right-side up. Asphaug bet Movshovitz that the wobbly pods would work better than the previous “sandwich” lander, even in microgravity.
Movshovitz made the lower half of the pod nine times heavier than the upper half. In his simulation, the lower half was colored red, the upper half green. The landers, descending to the simulated surface, look like tomatoes falling from heaven.
Every roly-poly lander popped right up, even one that had landed on its head. Asphaug won the bet.
Movshovitz also is using video game physics to study how asteroids break apart in a planet’s orbit. The physics will be key, he said, to understanding the balance between the friction that holds the asteroid together and the strong planetary gravity that could tear it apart.
Asphaug said he hopes to continue to take advantage of the computing power developed by the video game industry to advance science. Video gaming, after all, is a $65 billion industry obsessed with making graphics faster, smoother and closer to reality than ever before. NASA’s entire budget, by comparison, is less than $18 billion.
Movshovitz uses a high-performance gaming computer sporting a graphics card with around 500 processors. His black metallic keyboard features sharp, angular lines and an amber backlit glow. With such a machine, is there ever a temptation to play games?
“After hours,” Movshovitz said with a smile.
Researchers presented these ideas at the 2012 American Geophysical Union Fall Meeting in San Francisco in December.
Asphaug’s Arizona State University team is now working on real-life pod prototypes, about the size of two softballs end to end, to prepare for NASA’s next asteroid mission, launching in 2022.
“Time flies,” Asphaug said. “We’ll be ready.”