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Perseverance rover’s descent and touchdown on Mars [video]

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Re: Perseverance rover’s descent and touchdown on Mars [video]

#101

Post by Stratoscope »

soheil wrote: post #94
spookthesunset wrote: post #31

As it got closer to the ground, it seemed really hard to get a sense of scale with that downward camera. It felt like the ground just kind of "appeared" right before the sky crane did its thing. How big are the rocks under it? It felt like they were either big (1+ meter) or just little pebbles. I really couldn't tell. Either way, this is seriously the coolest video I think I've ever seen. I cannot wait for more.

Yes, something about not having the right perspective from the camera makes it very hard to judge how close it is to the surface. I guess sometimes I get the same feeling when in an airplane landing and going over water, SFO is a good example.

This is why the trickiest landing with a floatplane is when the air is still and the water is glassy smooth. You can't tell where the surface is as you descend!

Have a little wind to make ripples in the water and your job as a pilot is much easier.

https://www.aopa.org/news-and-media/all-news/2017/january/fl...

https://www.flytheshark.com/guide-to-seaplane-flying/takeoff...

Re: Perseverance rover’s descent and touchdown on Mars [video]

#103

Post by ardy42 »

joeyh wrote: post #53

This was recorded by a computer running Linux, using ffmpeg. Embedded Intel system with fairly stock cameras. "the first open source linux box running on the surface of Mars" "thank you to the open source community for allowing us to use your amazing software" Per their press conference today, in the Q&A section. https://youtu.be/gYQwuYZbA6o?t=4025

> Per their press conference today, in the Q&A section. https://youtu.be/gYQwuYZbA6o?t=4025

What was the model? The recording was garbled, and all I could hear was "...we're using a commercial computer, an Intel ???? PC. It's running Linux...

Re: Perseverance rover’s descent and touchdown on Mars [video]

#104

Post by kbaker »

giantrobot wrote: post #59
krm01 wrote: post #29

Earlier quoted context omitted.

It would be great to see some startups work on interplanetary video streaming tech. If you're building an other video streaming service, stop what your doing, and give this a try. I know I know. Very, very hard to solve and all, and this is totally a fanboy speaking, but it would have been awesome if we could have seen this footage in (as close as possible to) real-time when the landing happened.

Nothing about "interplanetary streaming" needs to be invented. The limiting factor is the size and power of the transmitter on Mars (or wherever). The MRO orbiter for instance is the highest bandwidth probe we've sent to Mars and it maxes out at about 4Mbps when Mars is closest to Earth. When Mars is farther it can only do about 500Kbps. That relatively prodigious rate requires the use of 34m receiving antennas on Ea…

Maybe that's what Elon has planned for the back side of the Starlink v2.0 satellites - to create an Earth-sized massively distributed phased array and get a super-high-bandwidth downlink from Mars.

Re: Perseverance rover’s descent and touchdown on Mars [video]

#105

Post by GeorgeTirebiter »

geocrasher wrote: post #34

This may sound silly, but: The closest I've coming to building a "robot" was a simple little arduino kit. The kit was terrible, the parts defective, and you can imagine I was pretty sick of troubleshooting it after a time. These are things happening on my workbench with a small amount of automation code. I'd have been thrilled if it had just worked as designed. Now, take three robots. One is wheeled, one flies by rot…

What if you had $ 2.7B? Would that help? (I'm not suggesting Percy is anything but a near miracle; only that they did have at least some non-trivial resources.)

Re: Perseverance rover’s descent and touchdown on Mars [video]

#106

Post by GeorgeTirebiter »

ardy42 wrote: post #103
joeyh wrote: post #53

This was recorded by a computer running Linux, using ffmpeg. Embedded Intel system with fairly stock cameras. "the first open source linux box running on the surface of Mars" "thank you to the open source community for allowing us to use your amazing software" Per their press conference today, in the Q&A section. https://youtu.be/gYQwuYZbA6o?t=4025

> Per their press conference today, in the Q&A section. https://youtu.be/gYQwuYZbA6o?t=4025 What was the model? The recording was garbled, and all I could hear was "...we're using a commercial computer, an Intel ???? PC. It's running Linux...

https://www.pcmag.com/news/linux-is-now-on-mars-thanks-to-na... talks about Ingenuity copter details.

Re: Perseverance rover’s descent and touchdown on Mars [video]

#107

Post by ardy42 »

interestica wrote: post #71

Observations Open source bits and shout out: - The rover has an Intel-based PC running Linux. - The video is compressed using FFmpeg. - https://youtu.be/gYQwuYZbA6o?t=4027 Images and Video and Data! - 30GB of data. 23 000 images - https://youtu.be/gYQwuYZbA6o?t=562 Cam Fail on Descent: - 1 of 3 cameras failed when the mortar/parachute fired. - Some other items were damaged/disrupted during the firing as well – not de…

Were there any scientific utility to these payloads, or were they added in order to create some spacecraft porn? How much did the equipment for this weigh?

IIRC, a downward facing camera is useful for precisely locating the landing location, but I'm having trouble seeing a purpose for the upward facing camera besides getting cool sky-crane video.

Re: Perseverance rover’s descent and touchdown on Mars [video]

#108

Post by donarb »

HarHarVeryFunny wrote: post #95
donarb wrote: post #43

Earlier quoted context omitted.

The more impressive part is that the sky crane shot pictures, video and data and had to download everything to the rover before it was cut loose. As soon as the rover wheels touched ground, the tether was cut and the lander flew away.

I'd like to know how they cut/released the tether, and if there's any fallback in case 1st release attempt fails. The entire mission is fucked if the tether release failed, or if the sky crane tries to fly away while still tethered.

They use explosive bolts that attach the tether to the deck of the rover. They're almost 100% fool proof. Here's a Wikipedia entry, they're called pyrotechnic fasteners and NASA uses a lot of them.

https://en.wikipedia.org/wiki/Pyrotechnic_fastener

Re: Perseverance rover’s descent and touchdown on Mars [video]

#109

Post by andyzweb »

GeorgeTirebiter wrote: post #105
geocrasher wrote: post #34

This may sound silly, but: The closest I've coming to building a "robot" was a simple little arduino kit. The kit was terrible, the parts defective, and you can imagine I was pretty sick of troubleshooting it after a time. These are things happening on my workbench with a small amount of automation code. I'd have been thrilled if it had just worked as designed. Now, take three robots. One is wheeled, one flies by rot…

What if you had $ 2.7B? Would that help? (I'm not suggesting Percy is anything but a near miracle; only that they did have at least some non-trivial resources.)

Was that the budget for the whole thing? If that’s what it cost to put that thing up there why aren’t we doing this once a month.

Re: Perseverance rover’s descent and touchdown on Mars [video]

#110

Post by croutonwagon »

AnotherGoodName wrote: post #89
wycy wrote: post #56

Earlier quoted context omitted.

Wow, very interesting. I had a pre-conceived notion that Martian atmospheric pressure was something like 20% of ours, but you're right, it's quite a bit lower than even that.

If only. >The minimum safe lower limit for the partial pressures of oxygen in a gas mixture is 0.16 bars (16 kPa) absolute. https://en.wikipedia.org/wiki/Partial_pressure If it was 20% that would be survivable with just an oxygen mask fwiw. Humans can go down to 16% atm pressure safely if they breathe 100% oxygen. The rest of the body can easily handle the pressure difference (1 full atm of pressure is equivalent to…

Uh....10 msw is roughly 2 atm.

It’s an additional atmosphere. On top of...the one we live in at sea level.

Also 100% O2 anything past about 4 msw will kill you. The MOD of pure o2 is 13 feet. Which is about 3.9 msw

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