Home » Science » Asteroids’ close encounters with Mars: Mars, not Earth, shakes up some near-Earth asteroids

Asteroids’ close encounters with Mars: Mars, not Earth, shakes up some near-Earth asteroids


Nov. 19, 2013 — For just about so long as astronomers had been in a position to look at asteroids, a query has long gone unanswered: Why do the surfaces of most asteroids seem redder than meteorites — the remnants of asteroids which have crashed to Earth?

In 2010, Richard Binzel, a professor of planetary sciences at MIT, recognized a probable rationalization: Asteroids orbiting in our sunlight device’s major asteroid belt, located between Mars and Jupiter, are uncovered to cosmic radiation, altering the chemical nature of their surfaces and reddening them over time. Against this, Binzel discovered that asteroids that mission out of the primary belt and go with reference to Earth really feel the consequences of Earth’s gravity, inflicting “asteroid quakes” that shift floor grains, exposing contemporary grains beneath. When these “refreshed” asteroids get too with reference to Earth, they spoil aside and fall to its floor as meteorites.

In view that then, scientists have idea that shut encounters with Earth play a key position in clean asteroids. However now Binzel and colleague Francesca DeMeo have discovered that Mars may also fire up asteroid surfaces, if in shut sufficient contact. The group calculated the orbits of 60 refreshed asteroids, and located that 10 p.c of those by no means go Earth’s orbit. As an alternative, these asteroids handiest come with regards to Mars, suggesting that the Crimson Planet can refresh the surfaces of those asteroids.

“We do not assume Earth is the one main driver anymore, and it opens our minds to the chance that there are different issues taking place within the sunlight gadget inflicting these asteroids to be refreshed,” says DeMeo, who did so much of the work as a postdoc in MIT’s Division of Earth, Atmospheric and Planetary Sciences.

DeMeo and Binzel, together with former MIT analysis affiliate Matthew Lockhart, have printed their findings within the journal Icarus.

Asteroid roulette

The concept that Mars could shake up the outside of an asteroid is a shocking one: As Binzel factors out, the planet is one-0.33 the scale of Earth, and one-tenth as huge — and subsequently exerts a a ways weaker gravitational pull on surrounding objects. However Mars’ place within the sun device locations the planet in shut proximity with the asteroid belt, growing the prospect of shut asteroid encounters.

“Mars is true subsequent to the asteroid belt, and in a technique it will get extra possibility than the Earth does to refresh asteroids,” Binzel says. “So that could be a balancing issue.”

DeMeo, who suspected that Mars could have a hand in altering asteroid surfaces, seemed via an asteroid database created by means of the World Astronomical Union’s Minor Planet Heart. The database presently contains observations of 300,000 asteroids and their orbits; 10,000 of those are thought to be close to-Earth asteroids.

During the last decade, Binzel’s crew has tracked the brightest of those asteroids, measuring their colours to resolve which can have been refreshed just lately. For this most latest paper, the researchers checked out 60 such asteroids, mapping out the orbit of every and figuring out which orbits had intersected with these of Earth or Mars. DeMeo then calculated the chance, during the last 500,000 years, that an asteroid and both planet would have intersected, developing a detailed come across that might probably generate asteroid quakes.

“Image Mars and an asteroid going via an intersection, and on occasion they are going to each come thru at very just about the identical time,” Binzel says. “If they simply barely omit each and every different, which is shut sufficient for Mars’ gravity to drag on [the asteroid] and shake it up. It finally ends up being this random course of as to how these items occur, and the way continuously.”

Fresh the face of an asteroid

From their calculations, the researchers discovered that 10 p.c of their pattern of asteroids handiest go Mars’ orbit, and no longer Earth’s. DeMeo explored different doable reasons of asteroid fresh, calculating the chance of asteroids colliding with every different, in addition to the chance for a phenomenon known as “spin-up,” during which power from the solar motives the asteroid to rotate quicker and quicker, probably disrupting its floor. From her calculations, DeMeo discovered no conclusive proof that both adventure would considerably refresh asteroids, suggesting that “Mars is the one recreation on the town,” Binzel says.

Even if 10 % of 60 asteroids would possibly not appear like a major quantity, DeMeo notes that given Mars’ small measurement, the truth that the planet may just impact one out of 10 asteroids is noteworthy. “Mars is extra highly effective than we anticipated,” she says.

The researchers add that now that Mars has been confirmed to refresh asteroids, different planets, reminiscent of Venus, will have an identical capabilities — specifically on account that Venus is nearer in mass to Earth.

“You take into accounts these asteroids going across the solar doing their very own factor, however there may be in reality much more occurring of their histories,” says DeMeo, who’s now a postdoc at Harvard College. “This provides you a dynamic concept of the lives of asteroids.”

This work used to be supported by means of the Nationwide Science Basis.