On the surface, Mars presents itself as a world on the verge of inhospitality.
Average temperatures that hover around negative 81 degrees. A thin, carbon dioxide-rich atmosphere sometimes rendered opaque by planet-wide dust storms that can even be seen from Earth. Gravity that’s just one-third of what humans have evolved to tolerate.
But the red planet’s features tell a different story.
Looking at photos captured by satellites in orbit, it doesn’t take much imagining to see Mars was likely once home to rivers of running water and enormous crater-lakes. With the right conditions, perhaps this planet that gets its rusty color from iron oxide-rich rocks could once have been suitable for life – or at least life as we know it.
This dichotomy has left experts asking one of the most difficult-to-answer questions in science today: What happened to Mars, and can the same thing happen here on Earth?
“We know that Mars had a bad past,” said Thomas Zurbuchen, associate administrator of NASA’s Science Mission Directorate. “We used our Spirit and Opportunity rovers (2003) to follow the water in search of answers as to why this once ocean world is now dry and desolate. Following those missions came our Curiosity rover, which landed on Mars in 2012 and is still operating.”
Augmented reality: Mission to Mars: Explore the Perseverance rover
Now it’s time for NASA’s next robotic explorer – Perseverance – to follow in the dusty tracks of its predecessors. After a 293 million-mile trek across the expanse since its July 2020 launch from Cape Canaveral Space Force Station, the upgraded rover is slated to land on the red planet at 3:55 p.m. Eastern Thursday.
Its target: Jezero Crater, a harsh surface feature that was likely once a deep lake fed by rivers of running water.
“Perseverance is our robotic astrobiologist, and it will be the first rover NASA has sent to Mars with the explicit goal of searching for signs of ancient life,” Zurbuchen said.
But before it can begin roving its targeted landing site at a neck-breaking 0.1 mph, Perseverance has to pull off a series of risky landing maneuvers all by itself.
Getting to Mars with help from a United Launch Alliance Atlas V rocket and interplanetary cruise stage was one thing, but slowing down from thousands of miles an hour to a soft 1.7 mph at landing is another.
This seven-minute process – from 3:48 p.m. to 3:55 p.m. Eastern – is known as the “seven minutes of terror.” Because signals take 11 minutes to reach Earth, human input in the event of a mishap is impossible – Perseverance is on her own.
The nail-biting entry is made even more tense by the fact that once mission managers at NASA’s Jet Propulsion Laboratory in California get the first confirmation of entry, Perseverance will have already landed – or crashed – in real-time. The unavoidable signal delay, however, is a short hurdle for teams that have been waiting for this moment for a decade.
“Landing on Mars is really all about finding a way to stop and land in a safe place,” said Al Chen, NASA’s entry, descent, and landing lead at the Jet Propulsion Laboratory in California.
As it approaches Mars’ thin atmosphere, the heat shield affixed to the front of Curiosity’s protective capsule will bear the brunt of fiery entry while also acting as an airbrake of sorts. A massive 70-foot parachute then automatically deploys, further slowing down the 2,200-pound rover.
“While coming down on the parachute, Perseverance needs to figure out where it is,” Chen said. “It’ll jettison the heat shield that protected us during entry and it will use a radar and a new system we call Terrain-Relative Navigation to figure out where it is.”
After the newly exposed radar and cameras have a lock on Perseverance’s location and landing prospects, it’s time for the riskiest part: dropping out of the protective capsule with a web of machinery and eight retrorockets, which begin firing to slow the rover down.
About 65 feet from the surface, the still-firing retrorockets slow Perseverance’s approach to 1.7 mph. The descent stage then kicks off the “Sky Crane Maneuver,” which uses strong nylon cords to slowly lower the rover down to the ground. After confirmation of touchdown, the sky crane severs the cords and flies off to put distance between it and the rover.
Perseverance is expected to begin transmitting photos of its new surroundings immediately after landing.
NASA’s 10-foot-long, $2.4 billion Perseverance rover is equipped with suites of technologies designed to aid in the hunt for life.
> Sixteen engineering and science cameras support safe navigation and help observe the surface from extreme closeups to far away. Some of these are part of larger scientific systems, like an ultraviolet spectrometer and another that uses X-rays.
> A seven-foot arm attached to the front of Perseverance includes a powerful drill that can pull core samples from rocks that interest scientists. The samples can then be sealed and stored in tubes inside the rover’s main body for more analysis later.
> Perseverance also has the capability to remove the stored samples and leave them in designated spots around Jezero Crater. A future mission – yet to be scheduled – could one day land on the red planet, pick up the tubes, then fly off to return them to scientists on Earth.
> Unlike older Mars rovers, Perseverance and its Curiosity sibling rely on nuclear power. Essentially a “nuclear battery,” both rovers use energy generated by the decay of plutonium to charge onboard lithium batteries during dormancy. While the Department of Energy-provided hardware can power Perseverance for up to 14 years, the rover’s mission is currently set to last at least one Martian year (two Earth years).
> Perseverance even has a friend hitching a ride for this mission: Ingenuity. This four-pound drone will host the first-ever flight on another planet during a roughly month-long window. Though it has no science hardware, two cameras will help steer the drone and teach NASA engineers how to fly on a world with an atmosphere just 1% as dense as Earth’s.
But why look for life – past or present – in the first place? For Manasvi Lingam, a professor of astrobiology, aerospace, physics, and space sciences at Florida Tech, it’s the ultimate journey.
“Any sign of life will of course be one of the most momentous discoveries in the entire history of humanity,” Lingam said. “Even if it is extinct life, just knowing that there was something out there is certainly Nobel Prize-level.”
Lingam admits getting even a hint of an answer usually leads to more questions.
Would finding life on Mars inform our perception of how common it is elsewhere in the universe? If life on Mars and Earth appear to be similar, could the millennia-old theory of panspermia – that life can spread via asteroids or comets, for example – see a resurgence? Or what if the discovery is so foreign that it doesn’t appear to rely on the building blocks of life we’re used to, like DNA and RNA?
“All of these questions are really fascinating,” Lingam said. “If you find something very alien, that’s great and we can try to understand what it is.”
“It might even have some practical implications because humans learn from biology all the time. That’s in fact how we’ve made a lot of drugs – we looked at actual organisms and borrowed ideas from them,” he said.
No follow-up rovers are solidly planned after Perseverance. Nicknamed “Percy” by her JPL mission managers, she’s on her own in Jezero Crater for the foreseeable future.
But what about dropping sample tubes for pickup by a separate mission? That’s still in the works at NASA.
Lingam said a sample return mission has two advantages for scientists: the breadth and number of instruments available on Earth vastly outclass what’s available on Perseverance; and despite technological advances, having a human eye looking at samples is still the preferred method.
For his research, Lingam would like to see more missions to Venus – a planet that hasn’t seen enough investigation surrounding potential for life, he said. Missions like Perseverance, combined with upcoming investigations of other parts of our solar system, will ultimately provide a more holistic view of the history of life.
“There’s definitely part of me that wants to believe there’s life in the oceans of Europa, that there was life on Mars, and potentially even in the clouds of Venus,” Lingam said. “It’s always more tempting to think of a cosmos that is filled with all kinds of weird and wonderful life because that would mean we’re not alone.”
“One should not allow the belief to cloud one’s mind about the data and the scientific method. But I do hope that there is life out there.”
Contact Emre Kelly on Twitter at @EmreKelly.
By the numbers: NASA’s Perseverance rover
- Length: 10 feet (17 feet with drill-arm extended)
- Width: 9 feet
- Height: 7 feet
- Weight: 2,260 pounds
- Top speed: 0.1 mph
- Power source: U.S. government-provided nuclear decay “battery”
- Distance traveled to Mars: 293 million miles over six months
- Equipment: Cameras, radar sensors, “arm” with a drill, scientific analysis instruments, capsules to store samples, Ingenuity helicopter attached to “belly”
Timeline: Seven minutes of Terror (All times Eastern on Feb. 18)
- 3:38 p.m.: Cruise stage separation
- 3:48 p.m.: Seven minutes of terror begin with atmospheric entry
- 3:49 p.m.: Moment of peak heating (2,400 degrees)
- 3:52 p.m.: 70-foot parachute deployment
- 3:52 p.m.: Heat shield separation (20 seconds after parachute)
- 3:54 p.m.: Perseverance separates from protective back shell and parachute
- 3:55 p.m.: Perseverance touchdown in Jezero Crater
Visit floridatoday.com/space at 3 p.m. Thursday, Feb. 18, to watch live as Perseverance targets a landing on the red planet.