The Perseverance rover is building up a stockpile. It’s collecting samples of Martian rocks, dirt, and air, and storing them in small tubes. A complex retrieval mission will gather the tubes and bring them to Earth in about a decade.

By then, scientists may be analyzing another set of samples — of Mars’s larger moon, Phobos. A Japanese mission, MMX, is scheduled for launch in about a year. It’ll land on Phobos and gather a few grams of material. Return to Earth is scheduled for 2029.

The two sets of samples will provide different details about Mars. Perseverance is inside a large crater. It’s exploring the delta of an ancient river that once filled the crater with water. The sediments will tell us about conditions in the distant past, when Mars was warm and wet. And they could contain evidence of microscopic life.

MMX will tell us about the formation of both Martian moons, Phobos and Deimos. They could be captured asteroids. Or they could be debris from an ancient collision that blasted some of the Martian crust into orbit. Recent observations of Deimos by another mission, from the United Arab Emirates, appear to favor the impact scenario. The samples could help scientists confirm it.

Mars is quite low in the west at sunset, and sets by the time it gets dark. It’s just visible from the southern latitudes of the U.S. — Miami or San Antonio — but lost in the Sun’s glare for those farther north.
 

Script by Damond Benningfield