They call it “seven minutes of terror,” those treacherous final moments of a 292-million-mile journey from Earth to Mars that will culminate Thursday when the Perseverance rover built at Jet Propulsion Laboratory enters the Martian atmosphere and touches down on the planet’s surface.
It’s a terrifying stretch, worsened by the helplessness of mission managers who must put all their faith in the spacecraft’s on-board computers to guide the rover to the surface of Mars, since the distance will make instantaneous communication infeasible.
In fact, it takes more than 11 minutes for signals from the rover to reach Earth, so by the time mission managers receive confirmation that the craft has begun to enter the Martian atmosphere, the rover may actually already have landed on the planet’s surface, in the heart of what’s known as the Jezero Crater.
“The Perseverance team is putting the final touches on the complex choreography required to land in Jezero Crater,” Jennifer Trosper, deputy project manager for the mission at JPL, said this week. “No Mars landing is guaranteed, but we have been preparing a decade to put this rover’s wheels down on the surface of Mars and get to work.”
Perseverance is the most technologically advanced rover ever sent to Mars, tasked with the primary mission of detecting signs of ancient life on a planet that has fascinated scientists and science-fiction buffs for decades. The rover will also be the first leg in a multi-pronged effort to transport samples of Martian soil back to Earth for the first time. The SUV-sized rover is also carrying an astronomical first — a small helicopter dubbed Ingenuity that will become the first such craft to fly on another planet.
“Perseverance is NASA’s most ambitious Mars rover mission yet, focused scientifically on finding out whether there was ever any life on Mars in the past,” said Thomas Zurbuchen, associate administrator for the Science Mission Directorate at NASA Headquarters in Washington. “To answer this question, the landing team will have its hands full getting us to Jezero Crater — the most challenging Martian terrain ever targeted for a landing.”
The rover launched from Cape Canaveral on July 30, 2020, propelled on its way by a United Launch Alliance Atlas V rocket.
Nearly seven months later, the spacecraft toting the rover will begin the landing procedure shortly after midday Thursday, when an entry capsule attached to the rover separates from the main craft. The separation is expected to be confirmed at 12:38 p.m. California time. That confirmation will come 11 minutes and 22 seconds later than the event actually occurred, thanks to the aforementioned delay in communications due to the distance across space.
Ten minutes later, the entry capsule and rover will enter the Martian atmosphere at a speed of about 12,100 mph, beginning the “seven minutes of terror.” Within a minute of entering the atmosphere, the bottom of the craft will be roasting at a temperature of 2,370 degrees as it descends toward the planet.
Roughly three minutes later, or 12:52 p.m. California time, as the spacecraft descends at supersonic speed, a parachute will deploy, slowing the craft to about 200 mph, followed 20 seconds later with the capsule’s protective bottom detaching from the craft. The separation of the bottom heat shield will trigger a high-tech radar and camera process designed to target a precise landing site.
At roughly 12:54 p.m., the “backshell” of the capsule will separate, along with the attached parachute, with a “jetpack” known as the descent stage firing its rockets to slow down enough for landing, while guiding the rover toward its touchdown site.
As it nears the landing site, the jetpack will lower Perseverance to the surface using three 20-foot-long nylon tethers, setting the rover on the planet’s surface at a speed of 1.7 mph — with final touchdown set for confirmation at 12:55 p.m.
After landing, the rover will first snap photos of its landing site and transmit them back to mission managers, who will assess the health of the rover and deploy a “sensing mast,” or “head,” so more photos can be taken. It will then take more than a month for a thorough inspection of all the rover’s systems and for an upload of software — the instructions for the rover’s mission on the Red Planet.
Last year, Katie Stack Morgan, a deputy project scientist at JPL, said the rover’s landing spot, Jezero Crater, is home to “one of the best preserved deltas on the surface of Mars.” She said the location will give the rover access to some of the oldest rocks in the solar system.
The study of those samples will address “some big-picture questions,” she said, including “how did the surface and climate of Mars evolve over time, how do rocky planets form and differentiate, and, of course, was life ever present on Mars.”
Perseverance includes an array of scientific instruments, and it will make space history on at least two fronts:
— the rover is equipped with a mini helicopter that will become the first ever flown on another planet; and
— Perseverance will also collect rocks and soil that will be stored for a future return to Earth, marking the beginning of an unprecedented round-trip journey to another planet.
The historic recovery of Mars soil and rock samples will be done in partnership with the European Space Agency. The Perseverance rover will drill and collect samples, then store them on the surface of the planet. Current plans call for the launch of a “fetch rover” in 2026 that will collect the samples, place them in a rocket that will launch from the surface of Mars, rendezvousing with an orbiter that will capture the samples and return them to Earth.
The “Ingenuity” helicopter, meanwhile, will allow for a wider exploration of the planet’s surface.
Perseverance’s primary science mission is astrobiological, searching for signs of ancient life. The mission is a natural extension of earlier rover missions that have uncovered evidence that the planet once featured running water. Scientists believe such water flowed in an ancient river and poured into a lake — in what is now Jezero Crater.
Mission managers said the 28-mile-wide crater in Mars’ northern hemisphere was home to a lake roughly the size of Lake Tahoe, roughly 3.5 billion years ago. Scientists hope the sediments that were dumped into the lake preserved organic molecules and other signs of microbial life.
Some of its additional scientific equipment will also help pave the way for future human missions to the moon and Mars. The rover is scheduled to operate for about two Earth years — or one Martian year.
Also aboard the rover: the names of 10.9 million people who signed up online. The names are included on three silicon chips embedded on a plate emblazoned with the words “Explore as one” — in Morse Code.
NASA will provide a live online broadcast of the Perseverance landing, beginning at 11:15 a.m. at www.nasa.gov/live.
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