For the thousands of people who work on a spacecraft that journeys to Mars, the result of their efforts often remains unseen once it leaves Earth. That all changed this week when NASA’s Perseverance rover returned the first-ever video of a descent through the Martian atmosphere and safe landing on the red planet.
The footage gave the world a glimpse of an often entirely invisible process, including the deployment of the parachute to slow down the spacecraft after entering the atmosphere.
The 70.5-foot supersonic parachute was an extraordinary engineering challenge, said Ian Clark, systems engineer at NASA’s Jet Propulsion Laboratory in Pasadena, California. Clark, who has been at JPL since 2009, worked on the parachute for years. He led three tests of it on Earth to ensure that the parachute could survive inflating in wind that would be twice the speed of sound, or Mach 2.
“We did testing that hadn’t been done really since the Viking program (in the ’70s and ’80s), which was supersonic parachute testing of scale parachutes,” Clark said.
The parachute testing was carried out at NASA’s Wallops Flight Facility in Virginia in 2017 and 2018. The testing team replicated the Martian environment by using sounding rockets to reach halfway to the edge of space at twice the speed of sound and deploying the parachute.
Nylon, Technora and Kevlar were used to make the largest parachute ever sent to Mars, material that was three times stronger than what was used for the Curiosity rover landing in 2012.
The team felt confident in their testing, but it all came down to the parachute’s main performance on Mars.
A secret code
Easter eggs have a history of being part of the missions NASA sends to Mars. For example, thanks to tiny holes in its wheels, the Curiosity rover — which has been exploring Gale Crater — leaves “JPL” tracks in Morse code as it makes its way around the Martian landscape.
While working on the parachute design, Clark knew there would be a lot of utility in creating a pattern. Patterns on parachutes help convey its orientation, how it inflates and whether there is any damage after inflation. Checkerboard patterns can be confusing, so Clark wanted to use something less uniform and more distinct.
Then, Clark and some of his fellow team members decided to have a little bit of fun.
Clark is a puzzle enthusiast. He does the New York Times crossword each morning. His mother also saves the puzzles from the Sunday edition in a manila envelope that she gives him every time he visits her.
He thought about encoding words using binary code. But what would the message be? While he has never been one to look at a motivational poster and derive much meaning from it, three words stood out to Clark: “Dare mighty things.”
The motto, taken from a Theodore Roosevelt speech, is in buildings all across the JPL campus.
“Week after week, I definitely never got tired of reading ‘Dare Mighty Things,'” Clark said. “And it’s not just the phrase, but it’s even the broader context of the speech. This great inspirational message really represented the culture of JPL and NASA as a whole.”
He also included the GPS coordinates for JPL on the outer ring of the parachute.
When the parachute inflated on Mars, only about six people, including Clark, knew about the existence of the message.
During a press conference where the video was shared with the public on Monday, entry, descent and landing lead Allen Chen teased that there might be something to decipher in the orange-and-white parachute.
Within hours, space fans began posting what they deciphered on Reddit and Twitter. Clark was excited to see others engaging in this kind of puzzle solving, especially so quickly, as well as the joy that spread after the video from Mars was shared.
Clark hopes that the images and videos from the Perseverance will inspire people and help them get through the challenges of their days.
Inspiration becomes reality
Missions exploring the solar system, like Voyager, Galileo and Cassini, have long inspired Clark.
As a child, Clark watch Carl Sagan’s “Cosmos,” the 1980 PBS show, recorded by his dad. Clark watched Sagan talk about the billions of stars in the universe and share initial images being returned by the Voyager probes as they flew by Jupiter and Neptune. It piqued his curiosity and made him want to become involved in aerospace engineering.
On February 18, landing day for the rover, Clark sat in the entry, descent and landing war room at JPL in Pasadena. He watched data come in over the computer screens and listened to the callouts of Swati Mohan, the guidance, navigation and controls operations lead for the Perseverance mission, describing what was happening.
Even the slightest thing can cause damage to the parachute “and ultimately lead to a bad day because of the chaos of the environment,” Clark said.
Wind moving in the wrong direction could have a catastrophic effect, causing the parachute to inflate inside out and destroy itself. Those who work in entry, descent and landing often point to the parachute as one of the aspects of a mission that scares them the most, because it’s one of the least predictable of the mission.
When Mohan said the parachute had deployed, Clark kept an eye on the speed of the spacecraft as it dropped down through the atmosphere. At first, it seemed a little too fast, given the distance between the rover and the ground.
But the parachute did its job, slowing the rover down, and it gently landed in a picture-perfect way.
When images and video from the descent began to come back, Clark finally knew the team’s efforts had paid off and the parachute inflated beautifully.
“The realization of what happened started bubbling up to the surface,” Clark said. “I told the person who sent me the images, ‘I think for the first time today, I feel happy.'”
With every mission, NASA builds on its previous successes. This first video of a spacecraft landing on Mars will be used by teams planning other missions for decades, Clark said.
The importance of this kind of footage can’t be overstated.
Some of the first parachute tests done for a Mars mission happened during the Viking program, almost 50 years ago. Footage of the tests on 16-millimeter film was thought to be lost to history, Clark said. But they were able to track it down to someone who donated it to a small museum in Bradenton, Florida.
Clark flew from Los Angeles to retrieve the film and have it restored and digitized. Now the footage is used to compare with their recent parachute testing.
Clark continues to work on the Perseverance mission in different ways. He was the assistant project systems engineer for sample cleanliness, ensuring that the samples the Perseverance rover collects on Mars in its search for ancient life won’t be contaminated by anything from Earth.
Those samples will be returned to Earth in the 2030s by follow-up missions, called Mars Sample Return. Clark will be the phase lead for the mission that retrieves those samples from the surface of Mars and back into orbit before they return to Earth.
“We’ve been wanting to do this kind of mission for nearly six decades now,” Clark said. “When we dare mighty things, we actually can accomplish phenomenal successes.”