Imagine your body floating weightlessly through space — a slight push and pull would allow you to easily change speed and direction.
Now, imagine having to send a 7,300-pound spacecraft racing through Mars’s atmosphere at 12,000 miles per hour. How would you safely land it on the Red Planet?
It turns out, with a lot of trial and error involving basic materials, such as nylon, that you can find in a fabric store.
“A lot of the times when we fail our parachutes [during testing], they failed spectacularly. I mean, it’s like you’re creating a confetti machine of nylon,” said Ian Clark, a NASA investigator in charge of testing Martian conditions.
“Most of the material of the parachute is kind of very thin stuff — it’s very lightweight nylon — not too dissimilar from what your camping tent is made out of, but actually somewhat lighter than even that. You know, the stuff that you could almost go into a Jo-Ann Fabrics and buy in rolls.”
Clark’s team is part of the Advanced Supersonic Parachute Inflation Research Experiment, ASPIRE, a project within NASA’s Mars 2020 mission to search for evidence of ancient life on Mars and store it for later return to Earth.
The main goal of ASPIRE is to make sure the rover is able to successfully land on the Martian surface. The Curiosity rover that NASA landed on Mars in 2012 weighed less than the 2020 rover, so the team has to account for the heavier vehicle. The key improvement to the upcoming mission is ensuring the nylon on the parachute is stronger and lighter.
Rocket and jet propulsion carries the rover most of the way, but the final drift onto the surface requires a parachute to cut through the challenging atmosphere of Mars.
ASPIRE scientists test their rockets at a NASA facility in Wallops Island, Virginia. After collecting data and making adjustments from a November 2017 trial run, the team is getting ready for its next test, scheduled for March 27.
In the test, a rocket is launched over the Atlantic Ocean, and a vehicle containing the parachute and other measuring tools detaches from the rocket. The parachute opens to slow down this vehicle as it approaches the landing spot. While there is not an actual rover onboard the test vehicle, it matches the mass of the final product.
The team then recovers the scientific instruments from the ocean and inspect the parachute.
“We look over every square inch of the parachute. We want to see: Were stitches beginning to fail? Were some of the stitches popping?” Clark said. “Kind of like you’ve seen stitches failing on your jeans or T-shirt.”
If too many stitches fail, the team tries to figure out what went wrong. Problems could vary from the stitching process to a flaw in how the parachute opens.
While ASPIRE aims to produce a working parachute, Clark said the team is working on creating the ideal test for the parachute because there are still two test launches to come.
One challenge with testing a parachute on Earth is that the speed of sound here is faster than on our neighboring planet. Sound causes drag, or resistance, on objects in flight. And scientists don’t have a way to slow down sound.
“At Mars, it’s about [705 to 720 feet] per second. And at Earth, it’s about [1,082 feet] per second — so it’s almost 50 percent faster at Earth,” Clark said.
So what does that mean when the parachute is tested?
“It means it’s probably going to actually inflate faster at Earth than it would at Mars, and it could be more stressing,” he said. “But not so [much] more stressing that we think it’s not a good test to do anyway.”