When NASA's Perseverance rover touches down next week, it will carry one of the strangest devices ever seen on Mars — a drone destined to make the first controlled flights on an extraterrestrial planet.
Dubbed “Ingenuity,” the drone weighs just 4 pounds, and it will stay stored beneath the rover’s belly while Perseverance runs through its initial surface checks and experiments.
But about the middle of April, the rover will scout out a flat area without large rocks to deploy the drone, and soon after that Perseverance will release Ingenuity to make the first flights on Mars.
“It's pretty unique in that it's a helicopter that can fly around,” said Tim Canham, the operations lead for the Ingenuity project at NASA's Jet Propulsion Laboratory in California.
“There was a balloon mission on Venus years ago, so we can't claim to be the first aircraft,” he said, referring to the two Soviet Vega space probes that deployed balloons attached to scientific instruments in the clouds on Venus in 1985. “But we can claim we’re the first powered aircraft outside Earth.”
Canham will coordinate the five test flights scheduled for the Ingenuity drone over 30 days, with each at least three days apart.
“The first flight will be very basic – it will just go straight up, hover and go straight down,” he said. “After that, we’ll do a couple of flights where we go horizontally, to test how it works.”
The car-size Perseverance rover has seven complex scientific instruments, so it can take panoramic video, monitor the weather, perform ultraviolet and X-ray spectroscopy on anything it finds, and look for signs of ancient microbial life.
But, Ingenuity will carry out no science on its test flights. It will only take photographs of the Martian terrain with its two cameras, one facing forward and one down.
Instead, the Ingenuity project is designed to show drones can be an important addition to the ongoing explorations of distant planets, Canham said.
“Our job is really to prove that the aerodynamics, as we've tested them here, work also on Mars," he said.
Mars is a hard place to fly, which is why Ingenuity weighs so little and needs two counter-rotating 4-foot-long helicopter rotors to stay aloft.
Although the gravity of Mars is just a third of that of Earth, the red planet has a very thin atmosphere with just 1 percent the pressure of Earth, which makes flying difficult.
Mars is also freezing cold – it gets down to minus 100 Fahrenheit at night in the giant Jezero crater where the rover will land, perhaps rising as high as 40 degrees during the day. The extreme conditions will test the drone’s design.
Canham explained that Ingenuity only has enough battery power so that each of its test flights can last up to 90 seconds, in which time it should fly about 330 feet.
Sensors will monitor aspects such as the drone’s altitude, movements, aerodynamic performance and how it reacts to gusts of wind.
The cold will also affect Ingenuity’s lithium-ion batteries, so keeping the drone warm overnight while recharging from its solar panels during the day is a big part of the project, Canham said.
“We have these 90-second flights, but then a lot of the time is spent running the heater,” he said. “I joke that we are a heater that occasionally flies.”
The concept of using drones on robot probes to explore the solar system is relatively new, and this is unlikely to be the last flight on another planet or moon.
NASA is already planning a more complex helicopter drone for Mars, and the proposed Dragonfly mission to Saturn’s moon Titan would launch in the late 2020s. It would deploy an entire drone helicopter probe equipped with scientific instruments in the thick but unbreathable atmosphere there, where it is much easier to fly than on Mars.
Planetary scientist Lori Fenton of the Search for Extraterrestrial Intelligence Institute (SETI) in California, who studies sand dunes on Mars and the challenges for robot Mars rovers, said she remembered a scientific proposal 12 years ago that suggested using a drone to study a field site somewhere in the western United States.
“[Some] panel members thought it was absurd that someone was requesting funding to use a ‘toy’ to do science,” she said. “Since then, the UAV industry has exploded, and here we are — about to land a drone on Mars that will do exactly the sort of reconnaissance that the review panel laughed at,” she said, referring to unmanned aerial vehicles.