New Impact Sites Spotted on Mars Though Fewer Than Expected

Researchers using images from NASA's Mars Reconnaissance Orbiter (MRO) have identified 248 new impact sites on Mars in the past decade - far less than predicted by previous estimates of 200 impacts per year.

The team also employed the University of Arizona's High Resolution Imaging Science Experiment, or HiRISE camera, to take pictures of the fresh craters at the sites where before and after images had been taken, thus allowing them to make direct measurements of the impact rate on Mars.

In particular, HiRISE targeted places where dark spots had appeared during the time between images taken by the spacecraft's Context Camera, or CTX, or cameras on other orbiters.

This decrease in estimated rates is significant given the fact that the best yardstick scientists currently have for measuring Mars' age is the timing of new craters.

Based on the new findings, the researchers have determined that the rate for how frequently new craters at least 12.8 feet in diameter are created is the equivalent to one each year on each area of the Martian surface roughly the size of Texas.

Earlier estimates, which were anywhere from three to 10 times that much, were based on studies of craters on the moon and the ages of lunar rocks collected during NASA's Apollo missions in the late 1960s and early 1970s, according to a press release from the University of Arizona.

However, this seemingly small number of new sites hasn't dampened the spirits of the study's author Ingrid Daubar.

"It's exciting to find these new craters right after they form," she said. "It remind you Mars is an active planet, and we can study processes that are happening today."

Furthermore, as co-author Alfred McEwen stated, because of their work, "Mars now has the best-known current rate of cratering in the Solar System."