As Perseverance careened toward Mars Thursday, the live broadcast from inside mission control oozed tension. It felt like science fiction to Swati Mohan, who managed the rover’s descent and kept the world updated on the spacecraft’s status.
Millions of people watched on their computers, phones, and television screens as NASA’s Jet Propulsion Laboratory in California monitored the final, harrowing leg of the spacecraft’s journey. The white-hot, super-fast, and incredibly precise entry, descent, and landing (EDL) sequence took a terrifying seven minutes — plus mission control was 11 minutes behind the rover’s moves because Mars is 100 million miles away. The significance of the moment and uncertainty of its outcome was intoxicating.
Throughout it all, Mohan gave a play-by-play account. When Perseverance was one minute away from preparing for its Mars entry all on its own, Mohan had a surreal thought.
“I just had this momentary lapse into science fiction where you hear them talking about these in rockets in Starship Enterprise,” said Mohan. “I just said that! But it’s real, it’s not a movie, it was real. It actually happened to something that we built”
Not even 24 hours after the rover safely landed, it was all still slowly sinking in for Mohan, the mission’s guidance and controls operations lead.
“In the moment it was kind of weird,” said Mohan. “There were a few key moments where I had this, ‘Oh my god we’re actually doing this’ type of feeling.”
The broadcast feed bounced between different team members as more information trickled in. A jittery kind of buzz emanated from the team. With an incoming speed of 12,000 miles per hour being slowed down to a leisurely 1,000 miles per hour by Mars’ thin atmosphere, there was only one thing that stood between success and a devastating crash: a parachute.
“The parachute is one of the most important single point failures for entry, descent and landing, because there’s only one,” Mohan explained. “If there’s any tiny hole, tiny nick, the whole thing disintegrates and you’re left pummeling to the ground in a matter of seconds after that. If the parachute doesn’t work, it’s completely game over.”
“I was just so in the zone.”
When Perseverance informed the crew it’s parachute was deployed, the hard part wasn’t over. The team had to wait a few seconds before they knew that the craft had actually decelerated.
“It was working,” she said. “With the huge deep-space antennas that we were pointing at Mars, we could actually see the vehicle decelerating. That was another moment that was just incredible. We passed this super critical moment and we could actually tell that it did what it was supposed to do.”
The relief from the team was palpable as applause broke out.
Mohan had a flowchart written up of what to say depending on certain outcomes. The team had to be prepared for failure, of course, but once the calls came through that the landing was a success, Mohan was all business. At the end of the journey, when eight years of work paid off, Mohan slipped into her planned response.
“I was just so in the zone,” she said, recounting her thoughts. “’OK I heard these three calls, I’m supposed to say this, I got that.’ So I said it, and a few seconds later, everyone was up and cheering. It took me a few minutes to realize that I said it. It meant we were done! My job was done. We were actually on the surface.”
Not only was Perseverance safely on the surface, it picked a great spot to touch down on using its terrain navigation system, right between a few hazards including boulders and uneven terrain on a nice, flat stretch of Martian land.
With Mohan leading the team and one of only two people speaking during NASA’s broadcast, she was a visible inspiration to many. Mohan emigrated to the United States from India with her family when she was 1 year old and has worked on multiple NASA missions, including the Cassini mission to Saturn and its moons.
Most of the team involved with the space cruise from Earth to Mars and the subsequent entry, descent, and landing are done with their jobs, Mohan said. But the work isn’t quite over yet.
“We are super excited to get the data back of how well we did and trying to understand the nuances of what actually happened,” she said. “Now that Perseverance is on Mars, that means we have this first leg of Mars sample return, so the opportunity is there now for the next mission that will go back to Jezero Crater to get those samples and come back, which means there will have to be another mission to Jezero Crater to get the samples! We want to learn as much as we can from this one to build on it for the next one.”
While successfully getting Perseverance on Mars was exciting, Mohan said it was also tough because not everyone was able to be there. The pandemic forced NASA to staff mission control in more limited shifts.
“We always planned that we would all be in the room together, but less than half of us actually got a chance to be there,” she said. “It was wonderful being there with all the ones who could be there, but bittersweet missing all the ones who couldn’t.”
A lot of people worked really hard over many years to get to this point, putting so much of themselves into this mission.
“I just want to reiterate how wonderful the whole team was. It’s not easy to do this,” Mohan said. “The success was only possible because the whole Perseverance team shared that mindset of wanting so badly for it to succeed that they put their heart and souls and diligence and dedication and passion into it.”