NASA's Mars Helicopter has earned a ticket to the red planet.
The space agency announced that the diminutive aircraft, in development since 2014, earlier this year aced a series of rigorous flight tests under conditions mimicking the Martian atmosphere. The helicopter returned to NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California, in mid-May for more testing and refinements.
NASA expects to complete final tests and finishing touches so it can be attached to the belly of the Mars 2020 rover this summer.
"But we will never really be done with testing the helicopter until we fly at Mars," MiMi Aung, project manager for the Mars Helicopter at JPL, said in a statement.
Earlier this spring, the successful proof-of-concept was met with thumbs-up, smiles, and hugs from the team behind the four-pound, solar-powered copter when it successfully completed a series of test flights.
"Gearing up for that first flight on Mars, we have logged over 75 minutes of flying time with an engineering model, which was a close approximation of our helicopter," Aung, said in a statement. "But this recent test of the flight model was the real deal. This is our helicopter bound for Mars. We needed to see that it worked as advertised."
While it shares design cues with helicopters and drones built to operate on Earth, the Mars Helicopter is decidedly at home on Mars. In addition to being built to spacecraft standards to endure the g-forces and vibration of launch, its radiation-resistant systems can also operate in the frigid conditions on the Martian surface, which can go as low as minus 140 degrees Fahrenheit.
Despite its relatively large size, the more than 1,500 individual pieces of carbon fiber, flight-grade aluminum, silicon, copper, foil and foam that compose the aircraft were all engineered to keep its weight to a minimum. Using lightweight materials is absolutely critical for flight in the thin Martian atmosphere; comparable here on Earth to 100,000 feet in altitude. As a result, its nearly four-foot-long blades need to spin between 2,400 and 2,900 rpm, about 10 times faster than a conventional helicopter.
"To get that combination, to build a vehicle that’s capable of spinning fast and being able to control it, plus to be able to have the level of autonomy that's needed for operation at Mars, while still building it to be light enough to be able to lift in 1 percent atmospheric density, those are the challenges that we overcame," Aung told SpaceFlightNow.
To test the helicopter's performance under Mars conditions, the team used JPL's Space Simulator. The 25-foot wide vacuum chamber, which has hosted historic spacecraft from Voyager to Cassini, is capable of accurately creating conditions similar to those present on the Martian surface. But it wasn't just enough to replace the atmosphere. For the first time, the engineers also had to remove a sizable portion of Earth's gravity.
"Getting our helicopter into an extremely thin atmosphere is only part of the challenge," Teddy Tzanetos, test conductor for the Mars Helicopter at JPL, said. "To truly simulate flying on Mars we have to take away two-thirds of Earth's gravity, because Mars' gravity is that much weaker."
To pull this off, the team created a "gravity off-load system" that provided a tethered tug on the aircraft during its test flights. To the relief of everyone, the copter hovered with ease.
You can see the successful tests of the Mars Helicopter within the Space Simulator in the video below, which takes about 30 seconds to get to the key footage.
With Martian flight certification now complete, the helicopter will next be packaged with the Mars 2020 rover on its mission to the red planet in July 2020. Two to three months after landing in late February 2021, NASA expects to begin the first tests of the copter, with up to five flights of incrementally farther distances lasting a maximum of 90 seconds. Despite being a demonstration technology, the researchers expect the aircraft's high-resolution downward-looking camera to provide some historic views of Mars.
"The ability to see clearly what lies beyond the next hill is crucial for future explorers," Thomas Zurbuchen, associate administrator for NASA's Science Mission Directorate at the agency headquarters in Washington, said last May. "We already have great views of Mars from the surface as well as from orbit. With the added dimension of a bird’s-eye view from a 'marscopter,' we can only imagine what future missions will achieve."
Editor's note: This story has been updated with new information since it was published in April 2019.