Meteorologists are excited, too, because the probe could unlock secrets of the atmosphere of Mars — a planet whose average surface temperature sits near minus-80 degrees Fahrenheit. Daily temperature swings can exceed 150 degrees. Scientists have even captured imagery of dust devils, small whirling vortices, swirling across the Martian surface.
“For the first time, we hope that we will really have the ability to measure the [wind direction],” said Leslie Tamppari of NASA’s Jet Propulsion Laboratory in Southern California. She also serves as the deputy project scientist for NASA’s Mars Reconnaissance Orbiter.
Tamppari explained that there are twin wind sensors on Perseverance that allow scientists to deduce wind direction. The Curiosity rover, launched in 2011, was supposed to be able to do the same thing, but one of the sensors was damaged on landing.
“This time we protected [the wind sensor mechanism] by folding it in on itself so that upon landing, if anything got kicked up, it would not get damaged,” Tamppari said. “We hope we’ll have full vector winds from landing.”
Having accurate wind speed and direction data is integral to understanding how dust is lofted into Mars’s atmosphere.
Tamppari recounted planetary dust storms that swallow the entirety of Mars, blotting out the sun for six months at a time and causing surface temperatures to plummet.
“We have these global dust storms that happen every few Mars years, and we don’t understand why — occasionally one of the more frequent regional dust storms [can grow and] become global,” Tamppari said.
One such dust storm in June 2018 spelled the demise of Opportunity, a rover launched in 2003 that had been exploring the Martian surface for more than 14 years. Incident solar radiation, used to power the rover, dropped to zero beneath the thick shroud of dust, and more than 1,000 attempts to contact the rover over the next seven months were unsuccessful.
The addition of Perseverance also complements the Curiosity rover, since now scientists can obtain atmospheric pressure readings from two locations. That allows them to make deductions about the overall atmospheric flow and search for the triggering mechanisms behind dust events.
Perseverance is powered by what are known as radioisotope thermoelectric generators, meaning it’s not dependent on sunlight and should be immune to dust storms. Tamppari expects that it will be a number of years before the power source begins to degrade. If the rover does encounter a dust storm, the data it collects could prove invaluable, she said.
Tamppari and her team aim to piece together a general circulation model of Mars’s atmosphere, understanding how heat, moisture, dust and gases are transported over the course of a typical year.
“For the weather station, we are measuring atmospheric pressure, temperature, relative humidity, wind speed and direction, the dust in the atmosphere and water in atmosphere, particle sizes [and], for the first time, the net radiation,” Tamppari said.
She and her team are particularly interested in learning more about how water vapor is distributed in the Martian atmosphere, which is made up of 95 percent carbon dioxide. Much of the water vapor comes from solid carbon-dioxide ice caps at the poles that are vaporized during the winter, Tamppari explained.
Beneath that frozen CO2 is conventional water ice. “Water ice condenses first after the carbon dioxide, so with the solar energy heating the water ice cap, it puts that into the atmosphere. But we still don’t understand the whole transport,” Tamppari said.
Without weather balloons or any direct sampling equipment, NASA scientists have had to devise creative techniques to detect water vapor.
Tamppari described an apparatus on the rover called SuperCam, a set of tools that uses a camera, laser and other instruments to search for chemical compounds potentially supportive of past life on Mars. According to NASA, SuperCam’s instruments can “identify the chemical and mineral makeup of targets as small as a pencil point from a distance of more than 20 feet.”
“In the SuperCam instruments, we have a spectrometer that has the ability to detect water vapor,” Tamppari said. A spectrometer fires high-energy light at an object and can determine the object’s composition based on the wavelength at which it emits light, or electromagnetic radiation.
That doesn’t reveal how much water is present at different levels of the atmosphere but does offer insight into the total amount of water in a column of atmosphere. Tamppari hopes that data can be used in conjunction with surface observations to piece together a basic model of water vapor concentration with altitude.
At its core, Perseverance is one more observation station that can help provide a clearer picture of what’s going on in Mars’s atmosphere. Tamppari said that Perseverance will work in tandem with the Curiosity rover and, combined with data from satellites orbiting overhead, will track the motion of weather systems and attempt to understand their makeup.
Meanwhile, scores of other experiments will be ongoing simultaneously as the rover explores the Jezero Crater, about 19 degrees north of the Martian equator. Their goal is largely to look for signs of past life, while also collecting data to inform possible human exploration of the Red Planet.
“We [had] to land somewhere it’s not too rocky,” Tamppari said. “It has to be somewhere the spacecraft can slow down. And the higher elevations at higher latitudes, we can’t do that. This particular crater is what we ended up with.”
She explained that the crater has the remains of an ancient river inlet and an outlet, with what appears to be a river delta in the distance.
“On Earth, [a river delta] is a very good place to find microbes that might have been fossilized in the rock record,” Tamppari said.
What Perseverance finds remains to be seen.