Researchers set out to find out why most asteroids have a reddish tinge while meteorites (which have broken apart and fallen to Earth) do not.
The team believes the red color comes from radiation around the asteroid belt, which is located between Mars and Jupiter, an MIT news release reported.
Sometimes an asteroid will venture too close to Earth, and the force of the blue planet's gravity can cause an "asteroid quake." These quakes are believed to shift surface grains, revealing the fresh grains below that have not been affected by radiation.
If the "refreshed" asteroids come too close to the powerful Earth, they break into pieces and fall all the way to the surface (as meteorites).
This may not be the only explanation for the phenomenon. Researchers tracked the paths of 60 refreshed asteroids, and found 10 percent of them had never some close enough to Earth to cause a quake. These asteroids tended to have crossed Mars' path, which suggests the red planet has the same "refreshing" power.
"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," Francesca DeMeo, "who did much of the work as a postdoc in MIT's Department of Earth, Atmospheric and Planetary Sciences," said.
Researchers were surprised that Mars could refresh asteroids since it is only a third of Earth's size, is one tenth as massive, and has a much weaker gravitational pull. The planet is closer to the asteroid belt than Earth, which means more space rocks come in contact with its force.
"Mars is right next to the asteroid belt, and in a way it gets more opportunity than the Earth does to refresh asteroids," Richard Binzel, a professor of planetary sciences at MIT, said. "So that may be a balancing factor."
The team looked at over 300,000 asteroids documented by the International Astronomical Union's Minor Planet Center and picked out 60 that had been recently refreshed. They then made calculations to see if the objects could have passed by either planet within the past 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."
One more theory as to how some asteroids refresh could be an event called "spin-up"; where the Sun causes the object to rotate so fast that its surface is disrupted. DeMeo believes this is unlikely.
"Mars is the only game in town," DeMeo said.
