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Today it is a milestone in NASA’s Perseverance mission to Mars. At 1:40 pm today, Pacific time, the rover will have traveled 235.4 million km (146.3 million miles). This means the probe is halfway to Mars and its rendezvous with the Jezero crater. The spacecraft does not travel in a straight line and the planets move, so it is not equidistant from both planets.
“Even though we’re halfway through the distance we need to travel to Mars, the rover isn’t halfway between the two worlds,” Kangas explained. “In a straight line, the Earth is 26.6 million miles [42.7 million kilometers] behind Perseverance and Mars is 17.9 million miles [28.8 million kilometers] in front of.”
But today is still a good time to take another look at Jezero Crater and why NASA chose it as the mission’s goal.
The Perseverance rover has four general objectives. The two main ones are the search for environments that could have supported microbial life in the past and the search for evidence of that life. The other two goals are to store samples for later return to Earth on another mission and to test the production of oxygen from the Martian atmosphere in anticipation of future human missions to Mars.
Jezero Crater was chosen because it will hopefully support the first two goals particularly well. The crater is a paleolago, which means that it was once filled with water in the distant past. It was probably several hundred meters deep and about 40 km in diameter. Researchers think it may have filled with water on two separate occasions. They also think that the Jezero crater has been full for a long time and that the delta has taken 10 of them6–107 years to form. The lake and the canals that fed it were so long-lived that there can be up to 1 km of sediment on the bottom.
When NASA selected Jezero crater in 2018, the scientific case was strong. It has since grown stronger. Along with the preserved sediments and the river delta, there are five different types of rock the rover can sample. Some of Jezero’s features are estimated to be 3.6 billion years old. This is near the start of the Noachian period of Mars, which began between 4.1 and 3.6 billion years ago. The Noachian is when liquid water flowed over the Martian surface, creating networks of river valleys. There may have been oceans and large lakes at the time.
Perseverance will look for the signs of ancient microbial life. It has a suite of powerful scientific tools to do this. It carries ground-penetrating radar, several types of spectrometers, and a host of cameras.
The rover is actually a collection of different robots working together. One of these is the 2 m (7 ft) long robotic arm mounted on the front of the Perseverance Chassis. It has a rotary impact drill capable of collecting carrot samples for return to Earth. The sample return part of the mission is complicated and will be the first samples collected from another planet if all goes well.
Perseverance is equipped with 43 sample tubes and the mission’s goal is to collect at least a dozen samples. He will leave the samples in a central location for recovery on a future mission.
But Perseverance will also do important analyzes on its own. Its SuperCam instrument, an updated version of the Curiosity rover’s ChemCam, will use lasers and four sensitive spectrometers to identify potential chemical biosignatures in rocks and debris. And it can do it remotely, making the rover remarkably flexible. SuperCam is able to identify the chemical and mineral composition of targets as small as a pencil tip from a distance of over 7 meters (20 feet). Among other things, it can identify the types of “soil” that are most likely to preserve ancient specimens.
But all that scientific research is still a long way off. The spacecraft still has about four months of travel until its expected February 18 landing. But it’s fine; it’s not that Jezero Crater is going anywhere or changing significantly.
Once the rover reaches Mars, it has yet to land. And landing on Mars is not easy and is probably the most challenging and dangerous part of the mission.
But when it arrives, and if it manages to keep its landing, Perseverance may very well go down in history as the mission that has uncovered solid evidence of life elsewhere.
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