Failure may tackle many varieties subsequent week when NASA’s next-gen rover, Perseverance, reaches the floor of the Crimson Planet. Right here’s what must go proper—and the way issues may shortly go sideways—when Perseverance tries to make its much-anticipated touchdown.
For NASA, the entry, descent, and touchdown (EDL) of Perseverance on Thursday, February 18 presents quite a few potential factors of failure. NASA has said that “lots of of issues need to go good” for the rover to outlive the seven minutes of terror. We will’t take a protected touchdown without any consideration: As NASA factors out, solely “about 40 p.c of the missions ever despatched to Mars—by any area company—have been profitable.” Which, yikes.
In a nutshell, Perseverance must transition from speeds reaching 12,500 miles per hour (20,000 km/hr) to a strolling tempo over the course of a number of minutes. What’s extra, it’ll need to carry out this autonomously, because it takes practically 11 minutes for radio alerts to achieve Earth. To complicate issues, NASA is debuting two new applied sciences for the mission, each referring to the EDL part and each unproven.
All three phases—entry, descent, and touchdown—current their very own distinctive challenges.
The rover, nestled contained in the descent stage, will separate from the cruise stage, which, with its photo voltaic panels, radios, and gas tanks, will now not be required. Subsequent, the spacecraft must orient itself such that its warmth defend is going through ahead, a activity made doable by small thrusters positioned on the backshell. Throughout atmospheric entry, the spacecraft’s warmth defend might want to endure temperatures reaching 2,370 levels Fahrenheit (1,300 levels Celsius). A structural failure at this stage could be catastrophic, ending the mission earlier than it has an opportunity to get began.
Certainly, earlier missions to the Crimson Planet have failed proper on the Martian doorstep. In 1999, NASA’s Mars Local weather Orbiter entered into an orbit that was approach too low, inflicting the spacecraft to fritter away within the ambiance. The failure was ultimately traced to a conversion error, through which imperial items of pound-seconds weren’t transformed to the usual metric Newton-seconds. Hate it when that occurs.
Ought to the descent stage survive atmospheric entry, it is going to nonetheless need to take care of variably dense air pockets that might steer it off track. A guided entry will probably be carried out to keep away from this drawback, through which the descent stage will hearth small thrusters to compensate.
The unfurling of the 70-foot-wide (21.5-meter) parachute is subsequent. Ought to the parachute unfurl correctly and never get tangled, the descent stage will abruptly decelerate to 1,000 miles per hour (1,600 km/h), which continues to be blazingly quick (bear in mind, Mars has a brilliant skinny ambiance). The deployment of this supersonic parachute will depend upon an unproven new know-how referred to as Range Trigger, which is able to calculate the space to the touchdown spot and set off the parachute to deploy at simply the correct second. That is anticipated to occur roughly 240 seconds after atmospheric entry, when the descent stage is about 7 miles (11 km) above the floor. Perseverance will bid farewell to its warmth defend round 20 seconds after the parachute has unfurled, introducing one other potential level of failure.
This can be a vital stage—one with regrettable historic precedents. Through the failed landing of ESA’s Schiaparelli mission in 2016, the descent stage prematurely ejected the parachute and warmth defend, the results of a software program glitch. An onboard laptop thought it was just some toes off the bottom, however in actuality the descent stage was someplace between 1.25 and a couple of.5 miles (2-Four km) above the floor. You’ll be able to think about what occurred subsequent. The doomed Schiaparelli lander was touring at round 185 miles per hour (300 km/h) when it smashed into the Martian regolith.
With the warmth defend gone, and with the rover now lastly uncovered to the Martian ambiance, one other new know-how will kick in, referred to as Terrain-Relative Navigation. The correct execution of this device will probably be vital, because the chosen touchdown spot, a crater, is kind of harmful.
“Jezero is 28 miles broad, however inside that expanse there are lots of potential hazards the rover may encounter: hills, rock fields, dunes, the partitions of the crater itself, to call just some,” Andrew Johnson, principal robotics techniques engineer at NASA’s Jet Propulsion Laboratory, mentioned in a press release. “So, if you happen to land on a kind of hazards, it could possibly be catastrophic to the entire mission.”
Right here’s how NASA describes the brand new device, which ought to permit the touchdown craft to find out its place relative to the floor with a level of accuracy near round 130 toes (40 meters) or much less.
Terrain-Relative Navigation lets the rover make rather more correct estimates of its place relative to the bottom throughout descent. […] Utilizing photos from Mars orbiters, the mission workforce creates a map of the touchdown web site. The rover shops this map in its new laptop “mind,” designed particularly to assist Terrain-Relative Navigation. Descending on its parachute, the rover takes photos of the fast-approaching floor. To determine the place it’s headed, the rover shortly compares the landmarks it sees within the photos to its onboard map. Armed with the information of the place it’s headed, the rover searches one other onboard map of protected touchdown zones to seek out the most secure place it may attain. The rover can keep away from harmful floor as much as about 1,100 toes (335 meters) in diameter (concerning the dimension of three soccer fields end-to-end), by diverting itself towards safer floor.
The parachute ought to gradual the descent stage right down to about 200 miles per hour (320 km/h), requiring one final step for decelerate: powered descent with eight tiny retro-rockets. After ditching the parachute, the rover, nonetheless connected to its backshell, will cruise towards the floor from an preliminary top of 6,900 toes (2,100 meters).
Some 12 seconds previous to landing, and on the very cheap pace of 1.7 miles per hour (2.7 km/hr), it’ll be time for the skycrane maneuver. The backshell will decrease the rover utilizing three 66-foot-long (20-meter) cables, throughout which era the rover’s legs and wheels will transfer into their touchdown place. Perseverance, sensing an imminent touchdown, will let go of the cables, and the descent stage will zip off and crash—hopefully—far-off.
A number of transferring components, together with some projectiles, clearly make this an awfully sophisticated dance. The warmth defend, parachute, and backshell all threat damaging or in any other case interfering with the touchdown and/or the efficiency of Perseverance.
Once more, historical past supplies one other instance of a mission failing at this level, particularly NASA’s Mars Polar Lander, which, just like the Mars Local weather Orbiter, died in 1999 (not an excellent 12 months for NASA). Based on NASA, the “most possible explanation for the failure was the technology of spurious alerts when the lander’s legs deployed throughout the descent,” which “falsely indicated that the spacecraft had touched down on Mars when the truth is it was nonetheless descending,” inflicting the “most important engines [to] prematurely shut down,” ensuing within the lander falling to the Martian floor.
Ought to something go incorrect throughout the touchdown, Swati Mohan will probably be among the many first to know, as she’s the steerage, navigation, and management operations lead for the Mars 2020 mission. She’ll be at NASA mission management monitoring the progress and well being of the rover throughout the touchdown.
“Actual life can all the time throw you curve balls. So, we’ll be monitoring every part throughout the cruise part, checking energy to the digicam, ensuring the info is flowing as anticipated,” mentioned Mohan in a press release. “And as soon as we get that sign from the rover that claims, ‘I’ve landed and I’m on secure floor,’ then we will rejoice.”
The rover, although modeled on Curiosity, has many new options, together with an array of cameras and the flexibility to look beneath the floor with ground-penetrating radar. The rover will land at Jezero crater, the place it is going to seek for indicators of historic life. If life as soon as existed on Mars, a spot like Jezero crater—a former lake and river delta—would’ve been a really perfect place for microbes to hang around. Along with this essential astrobiological work, Perseverance can even research Martian climate and geology, deploy a small helicopter named Ingenuity, and gather samples for a future mission.
NASA may have a stay stream of protection of the touchdown, which is scheduled for February 18 at 3:30 p.m. ET (12:30 p.m. PT). We’ll be watching and hoping for the greatest.