Billions of years ago, Mars was a water world with rivers and lakes. Microbes may have swum in those waters, leaving their imprints on an ancient Martian bed called the Jezero Crater.
NASA sends a rover there to hunt for such fossils. The $ 2.4 billion SUV-sized robot, called Perseverance, will land in the Jezero crater on Thursday.
More than 3.5 billion years ago, rivers flowed over the edge of the 28-mile crater, keeping it full of water. This alien dam was about the size of Lake Tahoe. The rivers probably carried clay minerals into Lake Jezero, and if microbes lived in the water, they could have become trapped. This would mean that different fossil rocks, called stromatolites, are mentioned at the bottom of the lake bed, along the coastline or in the dried-up river delta.
This makes the Jezero crater one of the best places in our solar system to search for evidence of alien life.
On Earth, the oldest signs of life are 3.5 billion-year-old stromatolites found in ancient, shallow multi-beds – exactly what perseverance will seek on Mars.
An illustration of the Jezero crater as it may seem billions of years go by on Mars, when it was a lake.
NASA / JPL-Caltech
“It’s a tantalizing agreement,” said Ken Farley, the project scientist for perseverance, in a recent press conference. “It would, of course, be a wonderful scientific discovery to find that life exists outside of the earth.”
Perseverance is designed to sand Jezero crater, collect about 40 samples that may contain signs of ancient microbes and store them in special tubes so that a future mission can bring them to Earth.
NASA considered the crater as a destination for previous missions, but its steep cliffs, sand dunes and rock fields make it a dangerous place for robots to land. New technology equips the perseverance to tackle the treacherous terrain.
A journey from the bottom of the lake to the crater rim
NASA has carved a 15-mile orbital route to Mars using the diversified landscape of the Jezero crater.
A possible route to take perseverance over Jezero crater.
NASA / JPL-Caltech
“It’s a road that connects all the different habitable environments that we think exist in this lake and in its vicinity,” Farley said. “It’s a long traverse. It will take many years before we do it. However, the reason we do it is that it will enable us to bring the best possible set of monsters to Earth, to answer the most important questions. to answer about Mars and about life. ‘
Perseverance aims to land near the cliffs of the fan-shaped river delta – an abyss of mud and clay that the river left behind as it flows into the lake.
The remains of an ancient delta on the edge of the Jezero crater, captured by ESA’s Mars Express orbit.
ESA / DLR / FU-Berlin
The rover may end up on top of the cliffs of the delta, or he may first explore the muddy bottom of the lake for fossils and then climb to the delta. It depends on the places his autonomous navigation system chooses to land.
In the image below, the layer is green between the delta and the crater rim where scientists think the shore of the lake was from Jezero. It seems to be rich in carbonates: minerals that are especially good at trapping microbes to form stromatolites.
NASA’s Mars Reconnaissance Orbiter captured colorful spectral data that deposited clay and carbonates over the Jezero crater river delta. The green indicates carbonate minerals.
NASA / JPL-Caltech / MSSS / JHU-APL
If this is the case, endurance can simply wander along the carbonated shores of Lake Jezero and search for stromatolites.
The rover’s primary mission to search for signs of life lasts one Mars year (two Earth years). If the robot is still kicking when it is over, the extended mission will involve climbing the 1600 meter high edge of the crater.
The Jezero crater was probably originally created when an object (probably a meteorite) collided with Mars. The accident exposed rock layers deep in the earth’s crust. So, at the crater rim, Perseverance plans to study these layers to learn more about Mars geology.
An illustration of perseverance under the cliffs of the Jezero crater.
NASA / JPL-Caltech
The heat of the impact could also give rise to hot springs, which would have deposited their own minerals that could also contain signs of aliens.
“That’s why we’re so excited about the Jezero crater, because it has so many different ways to preserve the signs of life,” Briony Horgan, a geologist on the Perseverance Science team, said in the briefing.
Even if perseverance finds no fossils at all, it would be a great finding. To date, every habitable environment on earth that scientists have studied has offered life.
“If we do a deep investigation of the Jezero crater with the rover and its instruments … and we find no evidence of life, we will have shown that in at least one place there is a habitable environment that is not inhabited. is not, “Farley said. said. “If this is what we find, it will tell us something important: that habitability alone is not enough, that there must be something else – perhaps a magical spark – that gives rise to life.”