Mars' Effect on Asteroids More Powerful than Previously Believed

Researchers from Massachusetts Institute of Technology (MIT) may have solved the long-held mystery behind why the surface of most asteroids appears redder than meteorites, the asteroidal remnants that fall to Earth.

Since 2010, the predominating theory stated that asteroids located in the asteroid belt between Mars and Jupiter gain a reddish tint due to exposure to cosmic radiation, which alters its chemical nature over time. Author of the theory Richard Binzel further explained that any asteroids that left the herd and passed by Earth underwent "asteroid quakes" that renewed their surfaces.

A professor of planetary sciences at MIT, Binzel and his colleague Francesca DeMeo recently found that, while just one-third the size of our planet and one-tenth as massive, Mars appears to be capable of triggering these Etch-a-Sketch shakeups.

"We don't think Earth is the only major driver anymore, and it opens our minds to the possibility that there are other things happening in the solar system causing these asteroids to be refreshed," DeMeo said in a statement.

For the study, 60 asteroids were selected from a database of 300,000, of which 10,000 are labeled near-Earth asteroids. Through the years, Binzel and his colleagues have tracked the brightest of these, studying their colors so as to know when they refresh.

In the new report, DeMeo calculated the probability that each of the 60 asteroids and either planet would have crossed paths close enough that it would have generated asteroid quakes in the last 500,000 years.

"Picture Mars and an asteroid going through an intersection, and sometimes they'll both come through at very nearly the same time," Binzel said. "If they just barely miss each other, that's close enough for Mars' gravity to tug on [the asteroid] and shake it up. It ends up being this random process as to how these things happen, and how often."

In all, 10 percent of the sample asteroids only crossed Mars' orbit, and while that may not seem like a lot, it's much higher than previous estimates of zero.

"Mars is more powerful than we expected," DeMeo said.