Mars Has Twice As Many Close Calls With Asteroids Than Earth Does

Accident-Prone In 2013, a meteor fell to Earth in Siberia, injuring more than 1,000 people and causing more than $33 million in damage to infrastructure. Though this type of event is rare, asteroids present the biggest risk to planets. Now, scientists have found that Mars is even more at risk: A recent study shows that our neighboring planet faces twice as many close calls with potentially dangerous asteroids than Earth does. It’s obvious to scientists that the Red Planet is more at risk because it lies right next to the Main Belt, a stretch of asteroids and other space rocks flowing between Mars and Jupiter. But the risk had not been quantified yet. A team of astronomers at Nanjing University in China conducted simulations to determine how many asteroids get dangerously close to Mars each year. They labeled the rocks “close approach potentially hazardous asteroids”, or “CAPHAs” for short. The simulations incorporated the Yarkovsky effect, a force caused by sunlight that makes asteroids smaller than 25 miles in diameter either slow down or speed up, and potentially drift. The Yarkovsky effect can send some asteroids into gaps in the belt, where gravitational tugs from neighboring super-planets Jupiter and Saturn can kick the rocks out of orbit and toward other planets in the inner solar system, Live Science explained. Mars is the first target on this collision course. The researchers found that about 52 CAPHAs skim past it yearly, which is 2.6 times more than the CAPHAs threatening Earth. “As human visits to Mars become more frequent, the threat posed by Mars-CAPHAs may increasingly be taken seriously,” said Yufan Zhou, lead author of the study. But other scientists opined that this was a problem only secondary to the risk of CAPHAs hitting Earth. “Earth is still the place to focus such discovery efforts since Earth-approaching asteroids are the ones that pose an impact hazard to where humanity is actually located,” astronomer Rob Weryk told Popular Science.