Starship Asterisk*

Perseverance: Seven Minutes to Mars

Explanation: How hard is it to land safely on Mars? So hard that many more attempts have failed than succeeded. The next attempt will be on Thursday. The main problem is that the Martian atmosphere is too thick to ignore -- or it will melt your spacecraft. On the other hand, the atmosphere is too thin to rely on parachutes -- or your spacecraft will crash land. Therefore, as outlined in the featured video, the Perseverance lander will lose much of its high speed by deploying a huge parachute, but then switch to rockets, and finally, assuming everything goes right, culminate with a hovering Sky Crane that will slowly lower the car-sized Perseverance rover to the surface with ropes. It may sound crazy, but the Curiosity rover was placed on Mars using a similar method in 2012. From atmospheric entry to surface touch-down takes about seven minutes, all coordinated by an onboard computer because Mars is too far away for rapid interactive communication. During this time, humans on Earth will simply wait to hear if the landing was successful. Last week, UAE's Hope spacecraft successfully began orbiting Mars, followed a day later by the Chinese Tianwen-1 mission, which will likely schedule a landing of its own rover sometime in the next few months.

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Even though this approach to landing a rover was done for Curiosity in 2012, it's not a slam-dunk (no pun intended!). I'm feeling the same anxiety now as before. One way or another, I'll find relief when it's all over.

Interesting..........as was yesterday's discussion.

But, the idea here is PICTURE of the day.

Emphasis on artistry.

The yak-yak is interesting and informative............but keep it in your local version of a TED talk.....stick to the pics.

This picture is wrong as the ship will have at this moment of the descent only 4 of its 8 motors working (the external ones) in order to avoid burning the rover.

Very nice video explaining the descent in details (but in French !) : https://www.youtube.com/watch?v=UNT93jq ... sSpatiales

It's all go time now; right? I mean no backing out!

I checked this out; https://mars.nasa.gov/mars2020/spacecraft/rover/ Wow! a lot of stuff on that little vehicle!

It does sound crazy. If any cable gets hung up or fails to detach, it's over. How is this better than landing on rockets and driving away 100 meters?

raschumacher wrote: ↑Tue Feb 16, 2021 3:41 pm It does sound crazy. If any cable gets hung up or fails to detach, it's over. How is this better than landing on rockets and driving away 100 meters?

Interesting point. It really DOES seem to be way too complicated, but I'm sure smarter people than we, have determined that this is the least risky landing method. At least I sure hope this isn't just some pet project shepherded to actuality by a group of daring rebels Well, at least it has worked successfully at least once already.

majoroz wrote: ↑Tue Feb 16, 2021 8:05 am Interesting..........as was yesterday's discussion.

But, the idea here is PICTURE of the day.

Emphasis on artistry.

The yak-yak is interesting and informative............but keep it in your local version of a TED talk.....stick to the pics.

Well, videos are a sequence of pictures, so you're really getting your money's worth! Plus, this shows a lot of artistry, since there's a bunch of animation!

alter-ego wrote: ↑Tue Feb 16, 2021 5:32 am Even though this approach to landing a rover was done for Curiosity in 2012, it's not a slam-dunk (no pun intended!). I'm feeling the same anxiety now as before. One way or another, I'll find relief when it's all over.

Don't worry. We'll have plenty of time to be anxious all over again at the end of October when the JWST launches, makes it to the Earth–Sun L2 Lagrange point, and successfully unfurls itself. And just to add to the fright potential, the launch is currently scheduled for Halloween day! But based on its history to date, I'd say the chances of launching at all are about 50/50.

raschumacher wrote: ↑Tue Feb 16, 2021 3:41 pm It does sound crazy. If any cable gets hung up or fails to detach, it's over. How is this better than landing on rockets and driving away 100 meters?

Because the dust kicked up by landing would cause all sorts of problems with the rover. So it would have to be in a sealed enclosure, which adds weight and which just transfers reliability issues associated with detaching the cables to reliability problems with doors and ramps.

Explosive bolts are very old, very reliable technology. I expect that design reviews found this to be the lowest risk option.

johnnydeep wrote: ↑Tue Feb 16, 2021 4:15 pm

alter-ego wrote: ↑Tue Feb 16, 2021 5:32 am Even though this approach to landing a rover was done for Curiosity in 2012, it's not a slam-dunk (no pun intended!). I'm feeling the same anxiety now as before. One way or another, I'll find relief when it's all over.

Don't worry. We'll have plenty of time to be anxious all over again at the end of October when the JWST launches, makes it to the Earth–Sun L2 Lagrange point, and successfully unfurls itself. And just to add to the fright potential, the launch is currently scheduled for Halloween day! But based on its history to date, I'd say the chances of launching at all are about 50/50.

Yeah, it's a seriously technical endeavor alright, and I'll get more nervous about it when the launch occurs. However, the intensity of my anxiety is more peaked with Perseverance. The 7 minutes of not knowing and waiting for the result which so binary. Getting to L2 is relatively low risk, really not nervous about that. Even unfurling can have glitches and there'll likely be so backup plans for dealing with them and other operation issues. To me, a failure is more likely to be one in slow-motion. A dead JWST will most likely not be so decisive and startlingly sudden as the rover.