Once upon a time, an asteroid or comet got a bit too close to Mars, leaving a deep, permanent reminder of the encounter on the surface of the planet.
https://media.wired.com/photos/5b11b69f36ad230cb43f0d4a/master/pass/SPoW_01_06_01_18.jpg
Once upon a time, an asteroid or comet got a bit too close to Mars, leaving a deep, permanent reminder of the encounter on the surface of the planet.
https://media.wired.com/photos/5b11b69f36ad230cb43f0d4a/master/pass/SPoW_01_06_01_18.jpg