If you want to find life on Mars, carry a big drill. That’s the idea the European Space Agency and partner Russian Roscosmos have brought to the upcoming ExoMars mission and its planned Rosalind Franklin Mars rover.
“The deepest anyone has dug on Mars is six centimeters,” ExoMars project scientist Jorge Vago tells Inverse.
That’s a big deal, he says, since there are several factors — cosmic radiation, unmitigated ultraviolet light, and powerfully oxidizing perchlorates — that have likely destroyed any organic biosignatures in the top meter or so of Martian soil over the past billions of years.
“The recipe we have with ExoMars is we’re going to drill below all that crap,” to a depth of two meters, Vago says. “Our hypothesis is that if you go to the right place and drill deep enough, you may be able to get access to well preserved organic material from 4 billion years ago, when conditions on the surface of Mars were more like what we had on infant Earth.”
The rover, set for launch in 2022, will bring to a head a decades-in-development program that has suffered a series of setbacks. If all goes well, the Rosalin Franklin rover may be scientists' best shot at getting a definitive answer about whether there was ever life on Mars and what its fate can tell us about our own planet.
What is the Rosalind Franklin rover?
The Rosalind Franklin rover is an astrobiology lab on six wheels. It’s the mobile component of the joint ESA-Roscosmos ExoMars mission that also includes the Kazachok lander vehicle. Kazachok will land and release the rover on Mars’s Oxia Planum, an area believed to have once contained liquid water and may have been hospitable to early life.
“If we are lucky, it might have been the coastal area of a very large northern hemisphere ocean,” Vagos says. The Oxia Planum will also be the oldest site targeted by spacecraft so far, he adds, and is believed to be between 4 and 4.1 billion years old.
The rover will drill deep into the soil, bring samples into its internal array of instruments, and conduct experiments looking for biosignatures of potential life on Mars.
The rover itself is named in honor of the British scientist Rosalind Franklin, whose X-ray images of DNA were instrumental in the discovery of the double-helical structure of the DNA molecule by Frances Crick and James Watson. “She would have shared the Nobel Prize with them if she had not died of cancer,” Vargo says.
The Kazachok lander and Rosalind Franklin rover represent a second phase for the overall ExoMars mission, which began in 2016 with the launch of the Trace Gas Orbiter and ill-fated Schiaparelli EDM lander.
The Trace Gas orbiter is expected to continue studying the Martian atmosphere with a special focus on methane through at least 2023, but the Schiaparelli lander crashed during its descent to the Martian surface due to a computer malfunction. A problem with the lander’s inertial measurement unit, or IMU, which tracks the lander’s position on its descent, led the lander’s computer to believe it had landed while still a few kilometers in the air, according to Vago.
The Schiaparelli lander’s demise provided valuable data for ESA; however, the spacecraft’s final telemetry data led to improvements in the upcoming Kazochok and Rosalind Franklin rover mission.
“The 2022 mission implements a new, much more robust entry, descent, and landing (EDL) sequence, with redundant IMUs whose values are constantly being compared relative to what they should be by the capsule's computer,” Vago says. “In case one of them would go coo-coo, it would be taken offline.”
What is the Rosalind Franklin rover launch date?
The 12-day launch window for ExoMars opens on September 20, 2022, and closes on October 1. If all goes well, the Kazachok lander and Rosalind Franklin rover will launch on a Proton rocket from the Baikonur launch complex in Kazakhstan sometime in that window. “Regardless of when we launch, the landing is always on the 10th of June, 2023,” Vago adds.
The mission was most recently scheduled to launch in 2020, but “we were hit with a double whammy,” he says. “On the one hand, we were late with the software and some of the avionics boxes, so we couldn’t test them the way we wanted to. And then we were hit by Covid-19.”
What is the mission of the Rosalind Franklin rover?
“The main goal is to search for signs of life,” Vagos says, though there are many constituent steps the Rosalind Franklin rover will take in service of that goal. It will begin, he says, by studying geochemistry and potential biological signatures in the area around the landing site. “After you land, you look around and try to understand where you are and what it is that you see,” Vagos says. “It’s part and parcel of the exploration to try and understand the geology.”
The rover will then explore and drill in other locations, aiming to access any potentially preserved signs of life further beneath the Martian surface than any mission has reached before. It will be a deliberative process guided by the rover's many instruments to help with drill site selection.
“It is true we can go down to two meters, but it takes us almost five days to drill that deep,” Vago says. “It is a big commitment from the point of view of mission time to decide, ‘OK, I am going to drill here.’”
How big is the Rosalind Franklin rover, and what can it do?
The Rosalind Franklin rover is a middleweight, coming in at around 310 kilograms (683 pounds). Lighter than NASA’s 1,000 kilogram (2,204 pound) Curiosity rover, but heftier than the Russian Mars rovers at 186 kilograms (410 pounds).
Designed with difficult terrain in mind, the Rosalind Franklin rover has flexible wheels, which can also lock and serve as “feet” swung from articulated “knees” for traversing deep sand or steep dunes. “We can command a different type of gate in which we use the wheels as insect feet,” Vagos says.
Locomotion aside, the rover carries an arsenal of instruments designed to aid in its primary mission of searching for Martian life. A set of stereoscopic cameras on the rover mast aid in navigation, while a high-resolution 300-millimeter (~1 foot) camera is paired with an infrared spectrometer to help scientists decide where to explore. “Everything looks kind of butterscotch or orange-y,” Vagos says. “Having the infrared spectrometer gives you better information about the mineralogy.”
Once a potential drilling site is selected and the rover moves there, it can use the Russian-built Adron-RM neutron spectrometer to gauge how much water is in the soil beneath the rover. Too much moisture could interfere with measurements, Vagos says, “instead of crushing the samples to make powdered material, you would be sort of kneading dough to make bread.”
The rover also includes a French-made ground-penetrating radar to ensure the rover doesn’t attempt to drill through a slab of basalt a meter below the surface. The drill itself contains a microscope and an infrared spectrometer, according to Vagos.
Once a sample is acquired, it will be brought into the rover, where many tools can be applied to study the soil, including ovens and lasers designed to separate potential organic material from any perchlorates contained within the sample.
How will the Rosalind Franklin rover look for life?
The rover will use the ESA’s ExoMars Biosignature score, which applies weight to several different signs of life. These include morphological signs of life similar to stromatolites on earth, layers of sediment that are structured by bacteria colonies.
“After what, 25, 30 years of missions landing on Mars, nobody has seen any of these that would feel comfortable with saying, for sure we have detected a morphological biosignature,” Vago says. “But in principle, that is something you can and would want to look for.”
The most important biosignatures the rover will look for are chemical biosignatures, such as the presence of organic molecules of a certain “handedness,” Vagos says.
Organic molecules are either left or right-handed — that is, they have the same structure, but they are reflections of each other. If you make an organic chemical in a lab or a geological process, you get equal amounts of both.
“But if it is life that makes an organic molecule, it makes one type,” Vagos says, so finding only “left-handed” organics on Mars would be a strong sign of life.
But even that wouldn’t be strong enough to prove life existed on Mars. Vagos says evidence of organic molecules of a certain handedness would add 30 points to the Biosignatures Score, the most of any independent sign, but not enough on its own.
“What we claim is that if you get up to 100 points, then for sure you have demonstrated life was active,” he says. “The reason we say that is to be able to add 100 points, you have to have at least four or five independent biosignatures verified, and the chance that would happen just using geology is very, very low.”
How many rovers will be on Mars?
If the Rosalind Franklin rover successfully lands on Mars in 2022, it will become the eighth successful rover to land and operate on Mars, and will likely be the fourth rover active on Mars at that time.
The Chinese Zhurong rover landed in May 2021.