A high-powered camera on NASA's Mars Reconnaissance Orbiter spacecraft recently took a picture of a newly formed impact crater on Mars. Researchers know that the impact happened sometime between pictures of the area taken in September 2016 and February 2019.
Planetary scientists have concluded that the object that made the crater was actually fairly small, maybe five feet across. The crater it blasted was about fifty feet across. If a similar object had entered Earth's much denser atmosphere, it would have broken up or burned up harmlessly before reaching the surface. A meteor four times as large exploded in mid-air over Chelyabinsk, Russia in 2013.
This sort of thing actually happens quite often on Mars. The Reconnaissance Orbiter has spotted other new craters since it arrived in orbit around the planet in 2006. The largest new crater thus far, spotted in 2013 was about a 100 feet across.
Using spacecraft data, scientists estimate Mars is hit by about 200 small asteroid and comet pieces every year. The 2019 crater was the most spectacular because of the dark subsurface material thrown out then it hit. This material stood out against the red Martian terrain.
One reason NASA is interested in these asteroids is that they could pose a threat to Mars astronauts. Geologists also study the rates at which impacts occur so that they can use counts of craters to estimate how old different areas of the Martian crust are.