February 12, 2021

All landings on Mars are difficult, but NASA's Perseverance rover is attempting to touch down in the most challenging terrain on Mars ever targeted.

The intense entry, descent, and landing phase, known as EDL, begins when the spacecraft reaches the top of the Martian atmosphere. Engineers have referred to the time it takes to land on Mars as the "seven minutes of terror."

The landing sequence is complex and targeting a location like Jezero Crater on Mars is only possible because of new landing technologies known as Range Trigger and Terrain-Relative Navigation.

The Perseverance rover is set to land on the surface of Mars on February 18, 2021.

For more information about Perseverance, visit https://mars.nasa.gov/perseverance


[Al Chen] Nothing can be taken for granted when you get to Mars. There’s a lot of things we just don’t know.

[Swati Mohan] Space always has a way of throwing us curveballs and surprising us.

[Erisa Stilley] I mean, until we get the data that says we’re on the ground safely, I’m gonna be worried that we’re not gonna make it.



[Swati Mohan] Entry, Descent and Landing is often referred to as the seven minutes of terror. Because it takes about seven minutes to get from the top of the atmosphere of Mars to the ground safely.

[Matt Smith] The spacecraft has to do all of this by itself.

[Swati Mohan] There are many things that have to go right to get Perseverance onto the ground safely.

[Al Chen] There’s a lot counting on this. This is the first leg of our sample return relay race. There’s a lot of work on the line.

[Matt Smith] Starting about ten minutes before atmospheric entry, we get rid of really the spacecraft part of the rover that’s been supporting us.

[Chloe Sackier] We come screaming into the Martian atmosphere at twelve to thirteen thousand miles per hour.

[Erisa Stilley] And the heat shield is what dissipates all that initial energy through friction.

[Matt Smith] The vehicle will continue actually flying itself through the atmosphere. It’s sort of like a transforming vehicle that went from spacecraft and now it’s kind of like an aircraft actively guiding itself.

[Erisa Stilley] When we’re going slow enough we deploy a parachute.

[parachute deploys]

[Matt Smith] It’s the biggest supersonic parachute we’ve ever sent to another planet. It’s critical for slowing down the vehicle.

[Chloe Sackier] Perseverance’s Entry, Descent and Landing borrows heavily from that of Curiosity.

[Swati Mohan] But fundamentally, Perseverance is a different rover. She’s bigger, she has different instruments.

[Al Chen] We’ve added a lot of smarts on the inside to make it more capable so that it can deal with the landing site that we’ve given it.

[Matt Smith] The science team identified Jezero Crater as basically an ancient lakebed. And one of the most promising places to look for evidence of ancient microbial life and to collect samples for future return to Earth. The problem is it’s a much more hazardous place to land.

[Al Chen] When you look at Jezero, all you see is danger. How do we go to a site that we never thought was safe enough to go to before?

[Al Chen] So the heat shield, which has protected us all the way through entry, is no longer necessary. We need to get that off so we can actually see the ground. And we can see the ground in a couple of different ways.

[Swati Mohan] Perseverance will be the first mission to use Terrain Relative Navigation. So while it’s descending on the parachute, it will actually be taking images of the surface of Mars and determining where to go based on what it sees. This is finally like landing with your eyes open.

[Swati Mohan] Having this new technology really allows Perseverance to land in much more challenging terrain than Curiosity or any previous Mars mission could. Amongst the rocks and the craters and the cliffs - these things are hazardous to the rover but these are the things that are interesting to the scientists.

[Al Chen] Once Perseverance has figured out where she is, we jettison the backshell and the parachute, and light up our rockets.

[rockets whoosh by]

[Al Chen] Those rockets help us steer to a safe landing spot that’s nearby.

[Chloe Sackier] That descent stage takes us all the way down to about twenty meters off the ground.

[Al Chen] That’s when we start the skycrane maneuver.


[Al Chen] Once the rover has hit the ground, the descent stage will cut loose from the rover and fly away to a safe distance.

[Al Chen] Surviving that seven minutes is really just the beginning for Perseverance. It’s job, right, being the first leg of sample return to go look for those signs of past life on Mars- all that can’t start until we get Perseverance safely to the ground. And then, that’s when the real mission begins.


FEBRUARY 18, 2021

Commentary begins at 11:15AM PST





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