River deltas are ecosystems that are rich in life — so rich that many have figured prominently in earthly history, including the Nile Delta and Mississippi Delta, among others. But the ancient river delta discovered in Jezero Crater on Mars is far older than any of Earth's deltas, according to NASA's famed Jet Propulsion Laboratory. This otherworldly delta dates back billions of years ago to a time when Mars, now cold and dry, was warm and wet — and might have harbored life.

The Perseverance rover, which landed on Mars early last year as the centerpiece of NASA's Mars 2020 mission, is now exploring the ancient Jezero Crater river delta, looking for evidence of ancient life forms that may have once existed there. The same combination of flowing and standing water that makes earthly river deltas so ecologically productive could also make this one of the most promising locations on Mars to search for life.

Drilling Down

The Perseverance rover is aptly named because the search for life on Mars is unlikely to culminate in any one single "aha" moment, as Space.com explains. While a single spectacular discovery (such as an unmistakable fossil) is not impossible, it is much more likely that a great deal of patient spadework will be needed to persuade skeptical scientists. Researchers will demand extraordinary evidence for such an extraordinary discovery as extraterrestrial life — and rightfully so

Accordingly, the Perseverance rover was designed for spadework. Its design includes equipment not only for collecting samples and analyzing them but also for storing the most promising samples for a future return to Earth, where the full range of laboratory resources can be brought to bear on them.

According to Sky & Telescope, in August and September of 2021, the Perseverance rover passed its first big test, successfully bagging its first samples. An initial attempt went awry, with rock possibly fragmenting when the rover's rotary-percussive drill engaged. A follow-up attempt succeeded in collecting two samples for future examination here on Earth.

Things to Do on Mars

The primary mission of the Perseverance rover calls for a great deal of, well, perseverance. But as it drives around on Mars, the mission team has found plenty of other activities for it to take part in. In its first weeks on Mars, the rover itself was a bit upstaged by its sidekick, the drone helicopter Ingenuity, which successfully took to the Martian air.

Ingenuity's flights proved so successful that NASA has transitioned its mission from "technology demonstration" to "operational demonstration." In this role, it acts as a scout to assist in guiding Perseverance across the Martian landscape.

In March, Perseverance paused on its journey to shoot the first video footage of a solar eclipse on Mars. Phobos, the larger and closer of Mars's two tiny moons, passed across the disk of the sun, as seen from Jezero Crater. According to CNN, Perseverance was there to capture the video. Thanks to the frequent orbits of the close-in moons of Mars, eclipses are a frequent occurrence, and this was not our first image of a solar eclipse on Mars — though it is the first time we got video footage of the event.

Because Mars has a significant atmosphere (enough for a drone helicopter), it also has weather. As an additional report in Sky & Telescope explains, the Perseverance rover's weather-station mast has made a wealth of meteorological observations, including footage of powerful dust devils sweeping across the long-dry surface of Jezero Crater. Unfortunately, since the wind sensors in the weather station have to be exposed to measure the wind, they have encountered some damage during the dust storms. But mission engineers have hopes that software tweaks will restore full functionality to the instruments.

Return Delivery

Meanwhile, Perseverance is still in the early stages of its mission. Experience with previous rovers suggests that it will retain its capabilities for years to come. And so long as it operates, it can continue to collect samples that a future mission — planned for the 2030s — will collect for return to Earth.

For that very mission, a Northrop Grumman team is developing the rocket engine that will carry the return samples up from Mars and send them on their way to Earth, where researchers can fully examine the secrets gathered from Jezero Crater's ancient river delta.

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