NASA Mars rover Perseverance is scheduled to touch down on the Martian surface on February 18 in the 28-mile-wide Jezero Crater, which the scientists believe preserves evidence of a time when rivers flowed on Mars. The scientists are pinning hopes for signs of past life by looking for biosignatures, a clue that life once existed on the red planet. These biosignatures can vary from a specific isotopes or chemicals produced by living things, such as cholesterol, to something much larger, such as microscopic fossils.
“A dinosaur bone is an example of a biosignature that we find in ancient rocks on Earth,” says Briony Horgan, Purdue University associate professor of planetary science, who is a member of the Perseverance science team. Horgan led a study of the mineralogy of the site, which produced one of the major results that contributed to its selection. “I would love to find evidence that dinosaurs once roamed Mars, but instead we are going to be looking for biosignatures of bacteria-sized microbes.” She was also on the team that designed the camera that will be the scientific eyes for Perseverance.
The primary mission of the Perseverance rover is to look for signs of past life on Mars. Perseverance rover is designed to take photographs, video, pulverizing rock by shooting lasers to help scientists determine the chemical composition, using microscopes to search for organic molecules, drilling, analyzing and other scientific chores. The volume of data will be enormous which the scientists take years to analyze. Horgan and her colleagues are going to play forensic detectives, looking for clues and literally microscopic bits of evidence.
During the next decade, NASA is expected to bring back the samples stored in Perseverance. “It would not only be a feat of engineering to retrieve the samples and return them, but it would be the first time we would have samples brought back to Earth from another planet. That would be quite historic,” says Horgan.
The arm fetish
The car-sized Perseverance, NASA’s fifth Mars rover, is a technological hulk with a futuristic suite of technologies. But what interests Horgan is the scientific 7 foot robotic arm of the rover which has a lawn-mower-sized cluster of instruments.
“This robotic arm is really the workhorse,” Horgan says. “We can place it with millimeter precision, which is incredible. And out on the arm are these amazing microscopes that we can use to map minerals and organic materials at a very fine scale.”
It is not just the arms, at the top the mast of the rover there is a special dual-lens camera, Mastcam-Z, that Horgan has a special affinity for because she is part of the team that designed it and will help to operate the camera on Mars. The camera has a zoom that can view a housefly at the far end of a soccer field. The camera can record images in color, in 3D, and shoot video. It is precise enough that the scientists can use it for compositional analysis of the surrounding terrain.
“We can actually do some really simple spectroscopy looking at the wavelength dependence of sunlight reflected off of rocks to help identify their mineral fingerprints,” Horgan says.
The landing of the rover on Mars will be a tough job as the rover will descend in a giant fireball. “The fireball forms because the rover enters Mars’ atmosphere at 13,000 mph, generating a huge envelope of plasma around the rover. You can’t get radio signals through the plasma fireball. It takes seven minutes for the rover to go down to the surface from when it enters the atmosphere.
“But it also takes seven minutes for the radio signal to get back to Earth. So, by the time we receive the signal that the rover has hit the atmosphere, either it is actually on the surface of the planet doing well, or it has crashed into the surface. You just don’t know, so we’ll be anxiously waiting to get that first signal back from the rover to know that it landed safely. That’s why we call it the seven minutes of terror,” says Horgan.