Perseverance, which was launched from Earth on July 30, arrived on the Red Planet in mid-February and has been exploring the Martian surface and collecting various types of data.
Among them is weather data, which scientists say will better shape what we know about radiative processes and the cycle of water in Mars’s atmosphere. There isn’t much of it, but water trapped beneath solid carbon-dioxide ice caps at the poles can be vaporized during the summertime and enter the atmosphere. Part of the plan with Perseverance is to unlock clues about what happens after.
Perseverance is in Mars’s Jezero Crater, a site NASA chose for the rover’s landing thanks to its wide expanses, free of obstacles, and the presence of a dried-up river delta from 3.5 billion years ago.
On Saturday and Sunday, the rover’s Mars Environmental Dynamics Analyzer, or MEDA, reported a high temperature of minus-7.6 degrees, and a low of minus-117.4 degrees. That rivals the coldest temperature measured on Earth — minus-128.6 degrees observed at the Vostok weather station in Antarctica on July 21, 1983.
At least the winds on Mars were comparatively tepid, gusting to only 22 mph. But imagine that wind chill …
The MEDA probes for temperature at four different levels — the surface, 2.76 feet, 4.76 feet and 98.43 feet. While barely touching the surface of the lower atmosphere, the MEDA is expected to help offer insight into Mars’s radiation budget. In other words, scientists will learn how sunlight striking the surface is transformed into heat that enters and cycles through the atmosphere.
Perseverance isn’t the first spacecraft to return weather observations from the surface of Mars. Curiosity, which landed in 2011, suffered damage to one of its wind sensors. That meant that it could measure wind speed but not wind direction. Since Perseverance can tell from which way the winds are blowing, scientists are hoping to use its observations in tandem with those of Curiosity and satellite measurements to learn about Mars’s general atmospheric circulation.
Arguably of greatest utility to scientists in the short term is the potential for Perseverance’s observations to inform mission-critical decisions, and ultimately when the famed Ingenuity helicopter will be tested. The helicopter was previously lodged in the underbelly of Perseverance, where it was stowed for the journey to Mars; on March 21, Perseverance shed the graphite debris shield that had protected Ingenuity during travel.
Ingenuity’s first flight is slated for no earlier than Sunday, a touch later than the Thursday date originally projected. Even if the helicopter is in full working order, flying on the Red Planet is no easy feat.
The atmosphere, mostly made up of carbon dioxide, is barely 1 percent of Earth’s density. Helicopters on Earth can’t take off at high elevations because the air is too thin. Imagine that factor multiplied by 50 on Mars. NASA actually tested Ingenuity in vacuum chambers at its Jet Propulsion Laboratory in California.
That effect is acutely offset by Mars’s weaker gravity — about a third that of Earth. Still, working to construct a helicopter able to fly on Mars required years of engineering. Even the planet’s temperatures had to be taken into consideration; the extreme cold can “freeze and crack unprotected electrical components,” writes NASA.
And before it can roam, NASA plans to conduct test flights to make sure everything is in working order. Just deploying the helicopter to its launchpad will take 6 days 4 hours. During one of the final phases of deployment, Perseverance charged Ingenuity’s batteries before the cords were cut; then, the rover drove off, allowing sunlight to beam onto the helicopter’s solar panels to charge it.
During Ingenuity’s first test flight, its rotors will be spun at more than 2,500 revolutions per minute, and the helicopter will ascend through the thin atmosphere to just 10 feet. After hovering for up to 30 seconds, it will touch back down. NASA scientists will spend a few days gathering data and reviewing the flight’s performance before undertaking more complex endeavors in the future.
In the meantime, scientists will continue to await more detailed weather information from Perseverance and scope out an ideal airstrip for the helicopter. Ingenuity weighs only four pounds, its lightweight frame highly susceptible to even gentle winds.
Assuming an initial test flight does occur Sunday, NASA plans to host a live broadcast of the results early Monday.