On Monday, NASA announced that it had chosen a landing spot for its upcoming Mars 2020 rover. The site (more or less at center here) is called Jezero Crater, and it contains a delta formed by flowing water. NASA says that landing in its difficult terrain requires new technology that allows increased steering in the atmosphere.

Mars 2020 will be based on the design of the Curiosity rover, which is currently operating in Gale Crater, but it will have a different suite of instruments. The mission will have two focuses: to give us a better perspective on whether Mars has ever hosted life and to cache rocks for a sample return mission.

The details of how to get rocks back off the Red Planet are still being worked out. But there has been a steadily growing body of evidence that Mars had large amounts of liquid water on its surface in the distant past, and Mars 2020 will be about sampling some of what that water left behind in order to determine if it could have hosted lifeforms similar to those on Earth.

Some of that evidence indicates that the northern part of the planet once hosted an ocean. While Jezero Crater isn't far enough north to be in that basin, it's on the edge of where some volcanic highlands drop off into it. Imaging from orbit suggests that water flowing down from those highlands carved a path through the crater wall and formed a delta as it spread out within the crater. Thus, the floor of Jezero will preserve material from its own past environment as well as material eroded away from upstream of the site. NASA has already identified clays and carbonates that would have formed when water was flowing in the crater.

These features make Jezero Crater such an appealing target that this isn't even the first time that NASA has contemplated landing here. But the terrain is very complex, as it includes the uneven delta as well as boulders, pits, and areas filled with sand—enough to cause its rejection in the past. The people working on the new rover, however, have added some significant capabilities to its landing system. These include the ability to adjust when the parachute opens based on its trajectory and an imaging-based navigation system that will let the landing hardware fire small jets during the descent to adjust the landing site. Combined, NASA expects that the area covered by the landing site will be cut in half compared to Curiosity's landing earlier this decade.

While Mars 2020 is obviously still in the future, Mars fans can look forward to next week's landing of InSight, which will include a seismometer to track marsquakes.