If all goes according to plan, on February 18, the wheeled robot the size of a small car will complete its six-month-long, 292.5-million-mile journey and touch down safely on the Red Planet’s surface.
Should it succeed, Perseverance will be the fifth NASA rover ever to land on Mars, after Sojourner (1997), twin rovers Spirit and Opportunity (2004), and Curiosity (2012). The new rover, affectionately dubbed “Percy,” will scour the dusty, crater-strewn planet for evidence of ancient life and prepare the way for future human visitors.
But getting wheels on Mars is hard. Since countries began attempting to send spacecraft to the planet in the 1960s, just 40 percent of missions have succeeded. Some landers flew by Mars, missing the planet entirely, while others reached the planet but were destroyed on impact. “There’s always risk in any mission to another world,” says G. Scott Hubbard, a professor of aeronautics and astronautics at Stanford University. “You can’t avoid it.”
NASA will Livestream the February 18 landing on its Mars 2020 website beginning at 2:15 p.m. Eastern; the landing process is expected to begin around 3:38. Unlike the celebratory hugs and high-fiving in mission control after Curiosity’s landing in 2012, this year’s event will be more subdued because of the pandemic. Crew members at the Jet Propulsion Laboratory (JPL) in Pasadena, California, will be masked and limited to essential personnel to prevent the spread of the Covid-19 virus.
For the thousands of scientists who’ve helped Perseverance get to this point, nerves will be at an all-time high. “It’s a bit surreal. Mars is looming pretty big in the window right now,” says Swati Mohan, the Mars 2020 guidance, navigation and controls operations lead who will serve as the mission commentator during the landing event.
Mohan says the team has done as much as they can before the landing. “It’s just a matter of executing,” she says. “Now, we just have to trust in our team and the hard work that we’ve put in until now, to see us through to the finish line.”
Before tuning into Mohan’s play-by-play of the Perseverance’s landing event, here are a few things to know that will help you follow along.
After six months of travel, the actual process of entry, descent, and landing happens in just seven minutes. But because Mars is so far away from Earth, radio signals from Perseverance take about 11 minutes and 22 seconds to travel back to mission control. So, by the time mission control receives the signal that the rover has reached the top of Mars’ atmosphere, Perseverance will have already landed—or crashed.
Scientists call that tense entry, descent, and landing period the “seven minutes of terror.” Not only is that period the riskiest part of the entire mission, but the delay in communication between Earth and Mars means that Perseverance has to land itself completely autonomously. “There’s no joysticking that we can do,” Mohan says.
As mission control receives signals that the rover has completed each key part of landing—for instance, the signal that chutes have been deployed—they’re watching the fate of the rover reveal itself. Even though the events already took place minutes ago, the experience of waiting for the next transmission is nerve-wracking, Hubbard says: “You really feel as though you’re in the moment and it’s happening right then.”
How do you land safely on Mars?
What could go wrong?