Perseverance rover’s descent and touchdown on Mars [video] | Hacker News Reader

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

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507 pointsjvanderbot149 comments

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 rotors, and another is rocket powered. Put them on a rocket, fly to another planet, and land them autonomously without wrecking anything. As a hobbyist I'd be beyond myself to just do ONE of those. On Earth. Let alone millions of miles away on a distant planet.

And to get video of it just days later, bounced across multiple orbiters? Mind blowing.

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.

… or at least once every 26 months or so. [1]

[1]: https://en.wikipedia.org/wiki/Exploration_of_Mars#Launch_win...

We sent 3 separate spacecraft to Mars during the most recent launch window. We’ll see how we do next time around.

NASA’s budget is not what it used to be during the cold war and specifically during the race to the moon. The budget for 2020 was $22.6 billion.

Source: https://www.planetary.org/space-policy/nasa-budget

And a whole pile of experts who’ve done it before.

In the press conference they said they've spent 4000 man-years working on it.

Also, for all intents and purposes, the code driving these things are running in production for the first time. Of course they can do software updates now that it's on the ground. But the EDL code only gets one shot to run correctly.

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.

Agreed with both. I hope someone can eventually put an estimated 3D model of something familiar, like a person or a school bus or something, for scale in the image video.

And this is one of the coolest videos I've ever seen. I had a huge smile watching all of it. I can't even fathom how elated the whole JPL team must have been as these videos came in.

At about 2:57 the operator says the rover is about 20 meters off the surface, if that helps at all. I agree it got really hard to get a sense of the scale once the thrusters started blowing up dust.

I rewatched listening to all that and it helped but only in an abstract way. It's like there needs to be a penny in the shot or something to get a sense of scale.

No, not a penny. It needs a banana for scale

In deep space the banana would be frozen rock solid and would likely shatter if dropped. So, it seems the sky crane lowers the rover, and the rover lowers the banana.

Hah, totally agree. I assume the thinner atmosphere causes the dust to behave as if our view is much closer to the ground than it actually is.

It could also be the lens. The image feels a bit telephoto, not wide angle.

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...

Yeah, geology often seems self-similar at many different scales. I also was completely surprised when it was suddenly so close to the ground.

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

30 years ago

“ I'm doing a (free) operating system (just a hobby, won't be big and professional like gnu) for 386(486) AT clones. This has been brewing since april, and is starting to get ready”

I think it’s more than a hobby now...

I know Linux is way more then just one man, but holy hell what one person can inspire.

> 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.

https://link.springer.com/article/10.1007/s11214-020-00765-9 has details:

> The DSU is an off-the-shelf computer-on-module (CoM) from CompuLab Ltd with an Intel Atom processor and solid-state memory. The DSU runs the Linux operating system, along with additional software to communicate with the EDLCAM sensors, perform the EDL data collection sequence, manage the data storage and compress the collected data files. The DSU uses a high-density connector to provide connectivity to the high-speed USB3, USB2, gigabit ethernet and SATA interfaces.

> The main DSU is located inside the rover body. A second DSU, the descent stage DSU, is located on the descent stage. In both DSUs the CoM is connected to a custom electronics board that provides connectivity for all the USB devices. The two DSUs are almost identical to each other and communicate with each other through a gigabit ethernet link. The rover DSU includes a 480 GB solid-state flash memory drive (SSD) for data storage, provides a gigabit Ethernet link between both DSUs, and implements the high-speed serial communication protocol to communicate to the rover computer.

So what about the previous rovers? What were they using?

There is this emotion, not sure it has a name, which I am sure many engineers know -- when you prepare your system for a long time and then send it into the real world and watch it work...

You can feel it in this video, e.g when you see the crane fly away after accomplishing the mission.

If we don't have a name for this emotion yet, I hope the japanese or the germans invent one. :)

I'll just invent one: 'Funktionsfähigkeitsdemonstrationseuphorie'

Schöpferstolz. Schaffensfreude.

Now these points of data make a beautiful line

And we’re out of beta, we’re releasing on time

Pride

I think its similar enough to "closure" to re-use that word.

“It worked! On to the next task...”

It feels like watching your kids accomplishing something difficult on their own. The fear of mortality is loosened a bit.

Joy?

I don't know why I'm surprised at the amount of footage and the quality, but I am. This is really setting a new bar for missions like this, similar to what SpaceX has done in recent years. Stuff like this has got to be huge for getting interest and excitement from the general public and especially kids.

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.

So, the minimum delay between Mars and Earth is around 11 minutes, usually higher. And the bandwidth is something like 60 MiB/Sol. This is just totally unrealistic with any known tech for the foreseeable future

Current delay is ~11 minutes, but minimum is much lower (~4 minutes, per https://blogs.esa.int/mex/2012/08/05/time-delay-between-mars... ). We were last at that closest point in October, and the various voyages (this one, UAE's Hope, China's Tianwen-1) were timed so the closest pint was during the transit; we're a bit past it now.

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 Earth.

So if you wanted to stream video from a GoPro on a Mars orbiter you could do so with current technology, you'd just need to build some big-ass antennas on Earth and then build and launch the Mars orbiters. Besides being technically difficult (because rocket science) it would be really expensive.

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.

Wow. That's not how any of that works.

Oh, do explain a little more about why that doesn't work; wavelengths, total power, distances, etc.

Let me enumerate the ways.

1. Starlink satellites have Ku and Ka transceivers for uplink and downlink. They simply aren't capable of talking to any Mars probes using X band radios for Earth communications which is all of the current and near future ones.

2. A phased array can use beam forming to "aim" and to use aggregate receivers for resolution but they're seeing limited. Tiny receivers on Starlink satellites (even arrayed) would be no good for Mars probes even if they covered the right bands.

3. Every element involved in the question is in motion relative to every other element. Starlink satellites have orbital periods of about 90 minutes. Each satellite would only have Mars visible for at best half its orbit. With Mars effectively a point source any Starlink satellites arrayed to receive signals from Mars would need to rotate in sync to keep Mars in view. That necessitates pointing all a satellite's other antennas away from each other and Earth since they're all bus mounted. This means they can't simultaneously do Starlink and Mars relay tasks and you'd need a lot of Starlink sats to even begin to effectively receive Mars transmissions.

"You are wrong and should feel bad! I rest my case!"

Don't need particularly large antennas at the Mars end. Basically if you double the size of the antenna at the Mars end you can halve the size of the antenna back here on Earth.

So to establish a link comparable to the Earth-MRO link which has 35m dish here on Earth and 3m antenna at Mars, you could have a 11m antenna at both ends. The hard part is lofting that 11m antenna into Earth orbit in the first place (shipping it to Mars from Earth orbit is easy in comparison).

As an example you could cut the 11m antenna into two pieces, each being a half of a circle with 5.5m radius. That would easily fit into the SpaceX Starship cargo hold. Loft that into orbit, assemble it in orbit, then send it on its way to Mars. The only technical challenges there are flying a spaceship which hasn't reached orbit yet, and performing orbital assembly of a spacecraft (which hasn't been done yet).

Then for completeness put two more of those relay satellites at the leading and trailing Lagrange points for Mars so that we have communication with Mars even when it's on the other side of the Sun.

agree! I remember seeing still pictures from mars from the viking missions taken in the 70's and although they are pretty good this latest video quality and clarity means NASA/JPL has come a long way. Just seeing that alien surface where no person has(yet) walked is absolutely amazing.

I still can't get over the fact this mission has legit good cameras on it.

In case the other thread doesn't make the front page, they also added a microphone to this lander and managed to capture the sound of Mar's wind, which to me is almost more amazing:

https://soundcloud.com/nasa/first-sounds-from-mars-filters-o...

And it's not a Rick Roll. Well done.

Pretty cool, although it's so hard to really get a sense of sound of wind with a microphone. I guess the takeaway is that Mars is super quiet.

1% atmospheric pressure would do that. Sound won't travel very well through the Martian atmosphere.

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 being 10meters underwater as a guide, human orifices have no issue with it contrary to pop sci beliefs).

So yes it's not 20% and it would be nice if it was.

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

Yeah I was about to reply something similar. Wouldn’t want to go diving with those assumptions!

As in if you go 10meters underwater your orifices experience 1atm of pressure difference. In the reverse to space but the point being you can handle this just fine.

There's a myth that at low atm of pressures you pop and such. This is not true. You may need to breathe in/out to adjust but pretty much every part of the body can handle 1atm of pressure difference just fine. The 10meters below was intended as a reverse example but the point holds.

Except with pressure changes, physiology absolutely changes. There is some room for error within small changes..but at extremes its definitely different. (and Mars is 100% an extreme)

Its why in SCUBA you have to calculate MOD for nitrox. Because the partial pressures of oxygen will kill you. We only breath about 21% oxygen in air. And after rec depths, you often using different mixtures and take on decompression obligations, trimix, heliox etc. At certain pressures, things like HPNS will also have an effect.

You definately cant survive in a vacuum either with just a mask. Its why pressure suits are a thing.

I may be wrong, but I believe this goes back to a suggestion made decades ago by Carl Sagan. Despite being in the mission profile for a number of missions, it never made it (and turned on) until now.

https://www.planetary.org/sci-tech/mars-microphones

Obligatory audio from Venus, Venera 14 lander: https://www.youtube.com/watch?v=8jZDW53U8qQ&t=0s

With annotations: https://www.reddit.com/r/venus/comments/7vpr1w/sound_recordi...

So glad they've realized the value in allowing everyone to experience how hard these things are. So impressive, I can't wait to watch this video over and over.

The inflation of the parachute is spectacular, and knowing how hard it is, and how hard it is to test on earth - its just incredible.

And the skycrane was flawless - just so impressive how well it works. Too bad it flies off to crash and can't land gently somewhere to maybe be able to use it for its own purpose.

If there was mass available to add something to the sky crane, you'd be better off putting that thing on the rover, since the rover has the plutonium power pack.

I do feel a bit sorry for the crane as well though :)

This is what I was thinking. That sky crane has to be as barebones as can possibly be made. Every single bit of mass on it is something that could be better used elseware.

Tradeoff of course is if you skimp on the mass too much you'll get an unreliable sky crane and the whole thing is a dud.

Sky crane will be used for seismic measurements with another vehicle picking up the waves from it slamming into mars firma on the other side of the planet so some use of it at least!

SpaceX broadcasts really raised the bar on what the public expect from space, and with it brought a lot of excitement. Great that scientific program is following in those footsteps.

Ehh...to be fair, Space exploration has always been an excitement for public ever since the Apollo days. NASA's PR team has been stellar for over 50 years in inspiring people around the world. Indeed, SpaceX upped the game for live broadcast.

Let's put it this way - if SpaceX didn't exist, I am sure Mars 2020 program would have had high resolution cameras and videos of the landing, along with all the excitement from the public. It's just inevitable as technology progresses. Keep in mind that social media wasn't a thing back then.

NASA/JPL and the Perseverence program isn't following anyone's footsteps here.

360 view on surface. Viewable in VR

https://youtu.be/wE-aQO9XD1g

One of the engineers does a great shot-by-shot commentary of this video about 15 minutes into their live stream: https://www.youtube.com/watch?v=gYQwuYZbA6o

There have been made tremendous steps in simulation software. The fact that the crane mechanism has never been tested on earth besides simulations is incredible. Always wondered what software they use. Do they have a generic platform to run simulations on? Or is every mission written from scratch?

Not quite, the sky crane method was also used for Curiosity rover back in 2012

Here's a recording of the martian wind from one of the rover microphones https://soundcloud.com/nasa/first-sounds-from-mars-filters-o...

Personally, I didn't work on this, but I'm completely amazed. To think Curiosity did this 8 years ago as well is kind of staggering to me.

This is incredible quality. What's the file size of the video and what path did the data take?

The briefing said they had downloaded ~20 GB of data over the last few days. I'm sure much of that was _not_ EDL data.

30 GB of data and 23000 images. Crazy. https://youtu.be/gYQwuYZbA6o?t=562

I believe the data is uplinked through orbiters than relayed back from there.

It got sent back via orbiters ranging from the ESA's Trace Gas orbiter, the Mars Reconnaissance Orbiter or Mars Odyssey. Through those they can get up to 2 megabits per second [0] back to earth but that depends a lot on the orbiter it's talking to at a given time. The TGO is doing a lot and is one of the early high speed relays for the data from Perseverance. [1] There's also direct links to and from Earth but they're significantly slower.

[0] https://mars.nasa.gov/mars2020/spacecraft/rover/communicatio...

[1] https://scitechdaily.com/nasas-mars-2020-perseverance-rover-...

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.

That's relatively simple just wire them directly into the rover to start with so the data is always in the right place.

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

But the image of the cables show what looks to actually be a literal cut cable. Not just a connector being disconnected but a clean slice.

From today's Reddit AMA with the NASA team, they use pyrotechnics to set off a guillotine like device to cut the cables. Possibly something like https://psemc.com/products/pyrotechnic-cable-cutter/

Source: https://www.reddit.com/r/IAmA/comments/lpzbzo/were_scientist...

I don't know how they achieved it specifically, but there is a moment in the broadcast[0] they did where they show the umbilical on the rover and mention that it was cut. I'm curious as well how they did it!

[0] https://youtu.be/gYQwuYZbA6o?t=1898

I was really surprised at how fast the heat shield dropped away, and slightly disappointed that we didn't get to see it hit the ground.

HiRise captured the whole shebang: An image with the lander, heat shield, descent stage, and parachute. The descender is always a big black smear after these things, which is quite sad.

I'm looking for the link, but the NASA TV feed had it.

Here you go: https://www.nasa.gov/image-feature/jpl/perseverance-and-mars...

Well, there goes the rest of my afternoon.

Edit: no video I can find; I'd just find satisfying to watch it hit the ground, in real time.

I was hoping for the same, but at 9.5km away, and with a decelerating speed of 150m/s we wouldn't see but only a pixel.

I wonder if they have the time/it's in their plan to send the bot over to record where it landed, the state that it's in, etc. If they want to simulate assess the damage, it would be cheaper to make heat shield 50 of them on Earth and drop them from 10-15km. I assume that every minute is gold and they already got a X-days meter-by-meter plan on what to do with little room for free exploration.

> I wonder if they have the time/it's in their plan to send [Perseverance] over to record where [the heat shield] landed

I was thinking the same, but more for the fact that surely the impact has made a hole of some description that could be interesting to look into. Take advantage of the already expended energy to penetrate the surface layers.

But it would be contaminated, toxic and dangerous for the rover (it would contaminate or damage the instruments). Not worth it.

Can someone comment on why this is the first time I'm seeing videos from Mars versus previous missions.

Did the memory write speeds increase, more sensitive CCD sensors, easier to send data back to Earth?

I'm sure there must be some technological reason this wasn't done before because it's simply stunning...

There's a ton of media from previous mars missions. Can't comment on why you didn't see them

I'm curious about videos specifically. I've seen a lot of high-res images and animated GIF style videos but nothing like this.

One thing to consider is that NASA missions are basically always using older technology, because by the time the mission gets approved, designed, and built consumer/business tech has already moved past. Space worthiness ads more 'age' to the technology as well.

I remember when New Horizons flew by Pluto in 2015 taking pictures with a 1 MP camera. At that time I had an 8 MP camera on my phone, but remembered that in 2006 when New Horizons launched, the iPhone didn't even exist.

The current scale of video availability is very recent. Dirt cheap tiny HD cameras and storage & fast reliable networking to match, are only a few years old. Put that in context of a complex system expected to work perfectly under extreme conditions millions of miles distant, with early designs starting years ago, and that’s why you’re only seeing such now.

Not an expert, but my sense is that it's at least in part due to widespread cheap/commodity consumer cameras becoming a thing between the planning of Curiosity and the planning of Perseverance. In earlier missions, cameras were usually big and bulky and designed specifically for their respective research functions, and if you're designing something from scratch, you design it to maximize research utility first, and sending home cool videos is probably a secondary consideration. So I'm not sure many of these could do video (because it's probably not that useful for studying rocks that don't move), and a lot of them didn't even capture a spectrum range exactly matching the visible range (I think some of them included parts of the near-IR range, etc.), so a lot of the images from earlier missions that were released to the public had color that was faked/recreated in post-processing.

I think the new rovers still have these specialty cameras, but now that there are decently good mass-market cameras from the cellphone/consumer-electronics industry that cost $5 apiece and weigh a couple of grams, it seems like there's no reason not to throw a few of those onboard as well.

I would speculate, also, that video compression might be part of the story. Processors on these vehicles tend to be specialized radiation-hardened chips that are modified versions of several-generations-old general-purpose processors. I think Curiosity's was a rad-hardened 200MHz PowerPC chip, for example. I would bet that those chips just weren't up to the task of compressing high-quality video enough to make it practical to send, given the bandwidth constraints of transmitting from Mars to Earth.

It didn't have priority until now. Everything costs time and money and adds more complexity, more parts that can cause a failure. While videos are nice, they don't have such scientific value as another scientific instrument that could have been on board instead.

> While videos are nice, they don't have such scientific value as another scientific instrument that could have been on board instead.

While they don't have much scientific value, they have an extreme amount of value in a related field: marketing.

I mean, if you want more money for your hot new space rover mission nothing sells it better than high resolution quality videos of it landing on the surface of another planet.

The commercial cameras have gotten so good over the years so they could put cameras everywhere. They added some local storage to retain images for post processing. They post process the videos to a much smaller file before transmitting. So of-the-shelf technology keeps getting better.

It's not just cameras. What good is an 8K video taken on a rover but it can upload at 200 bits/sec?

The entire stack has improved. I suspect everything from radiation hardening, semiconductor manufacturing, CCD reliability and costs, image processors, colorometry, radio transmission, relay tech and orbiters, and not to mention the importance of great PR.

The most astounding (but logical) thing to me is that those guys are looking at that maneuver without being able to do anything to correct any error. Literally a recording from the past.

Watching history download in real time.

One of the engineers said that the parachute's patterns was both for visually determining the orientation (with computer vision), but also hinted there was some secret message in it. (at 19:34 in the livestream)

The rover wheels on Curiosity had gaps so that the tire tracks left a pattern in morse code that spelled out JPL, so maybe something similar? They eliminated that on Perseverance with the wheel redesign.

Yeah that's what I think, but it could also encode something longer. I am not sure on the parachute what is a science feature and what is an easter egg.

Someone figured it out: https://twitter.com/FrenchTech_paf/status/136399205173447885...

10-bit encoding via the three rings of colored panels; spells out "DARE MIGHTY THINGS".

Here is the full explanation

https://twitter.com/steltzner/status/1364076615932645379

After such a shitty 2020, this is just what we needed. Incredible.

When the parachute deployed all of a sudden it felt like mars is not so alien anymore, there is wind pushing against the parachute you can see the curvature of mars, there is sun, dust and all... Love this video compared to images.

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

> To date, no proof has been found of past or present life on Mars.

I wonder how long it takes until we get the first confirmation of some sort of life on Mars (e.g. something like bacteria or so).

Is this realistic already in the coming days?

1996: https://www.youtube.com/watch?v=pHhZQWAtWyQ

So far life on Mars was not really confirmed, right? I thought this is the main goal of this mission.

https://en.wikipedia.org/wiki/Perseverance_(rover)

> The rover's goals include looking for past Martian environments capable of supporting life, seeking out possible microbial life in those environments, ...

Also see: https://en.wikipedia.org/wiki/Life_on_Mars

> To date, no proof has been found of past or present life on Mars.

Nope. Still remarkable that a president would comment officially on a NASA finding like that. It's the closest thing yet.

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 desired, but expected
  - https://youtu.be/gYQwuYZbA6o?t=615

Parachute + Secret Message:

  - When packed, the parachute has the same density “as oak”.
  - it trails at about 150 feet.
  - The parachute pattern detail is intentional – sections to assist tracking different portions, etc.
  - There appears to be some sort of secret message encoded in the parachute: “sometimes we leave messages in our work for others to find…give it a shot and show your work”
  - https://youtu.be/gYQwuYZbA6o?t=1174
  - see also https://twitter.com/lqqkout/status/1363982243010473986

Mic Fail on Descent:

  - They did not get audio from the port-side EDL mic on descent due to a analog-to-digital comms malfunction
  - specifically stated that it was not a hardware issue.
  - https://youtu.be/gYQwuYZbA6o?t=3518

Other Descent Things + Sky Crane:

  - The heatshield is aeodynamically stable and does not tumble/spin on ejection.
  - No plumes from the ‘sky crane’ because the exhaust products of hydrazine are hydrogen and nitrogen.
  - The only hint that the rockets are firing are the slight colour change due to the heat (pink tint).
  - The photos/videos are the first views of the sky crane in action because it’s not something that can be tested on earth.
  - The photos/videos from the sky crane looking down at the rover at transmitted to the rover via an ‘umbilical cable’

Comms and photo things:

  - The High-gain antenna has only now been deployed. That’s the one that allows the high speed 2mbps rover-to-orbiter link.
  - https://youtu.be/gYQwuYZbA6o?t=2039
  - The data rate changes depending on the different orbiter being used.
  - “return 500-900 megabits per pass” and 2-3 overflights per night.
  - https://youtu.be/gYQwuYZbA6o?t=3928
  - And some of the biggest data relays were via European/ESA Trace Gas orbiter.
  - https://youtu.be/gYQwuYZbA6o?t=4097

The pieces:

  - There’s a shot of all the pieces and their landing/crash sites as taken from orbit. Heat shield, perseverance, back shell, descent stage/sky crane, parachute.
  - https://youtu.be/gYQwuYZbA6o?t=2251

Mic + Hardware things:

  - There are two mics. One captured some audio on the surface. A gust of wind. (more interesting to me was the hum of the rover). It would be cool if the audio from the mics could be used to pair with the panoramic view to create spatial audio.
  - https://youtu.be/gYQwuYZbA6o?t=2333
  - Because the EDL mic is ‘off-the-shelf’ it is expected to fail quickly in the Mars environment. They have no immediate plans to use it for any kind of diagnostics during its lifetime.
  - https://youtu.be/gYQwuYZbA6o?t=4215

Camera + Hardware things:

  - The cameras used are off-the-shelf commercial hardware with some modifications. Purchased from Point Grey Research (which was acquired by FLIR Systems).
  - Most interesting mod: they had to replace some materials that could off-gas in space/vacuum and potentially deposit on the detectors.

With all that, these press conferences are so weird. They still use a lot of acronyms. The setup is strange when there's no actual audience in front of them. They don't actually answer the questions from the press sometimes. They attempt to describe aspects of videos/images ("on the right you can see an antenna") instead of using technology to actually show. It's not quite clear who the audience is here: they're combining questions from kids and the press. It would be helpful if they annotated images. It would also be helpful to place the questions on screen (who has asked them). But, still so damn exciting.

//edit, formatting

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.

There is an engineering use for it, and that is to the see all the dynamic behaviour that other sensors might not capture. This is rocket science and they do want to know how the landing went.

In future, please don't put prose in code blocks, particularly links. You have a lot of good info here, but it's hard to read and non-trivial to follow the links on mobile. Thanks.

Ugh Didn't realize HN converted lines like that. I was trying to make it a bit more readable. Thanks for the heads up! (Too late for an edit)

It's a lot better than last year, when code blocks didn't even wrap on mobile. The only formatting HN allows is paragraphs, italics, and code blocks, with auto-links. So you're forced to do lists as a bunch of paragraphs.

I'm really surprised at how much dust was being kicked up despite the length of the sky crane. I thought the whole point of that was to reduce/minimize the dust that would get kicked up. I'd like to suggest that NASA use a longer cable next time :)

I'd love to see this video with some real-time overlays. Landing spot identification with a 90% confidence zone, hazard identification, altitude, etc. I'm also curious how much hazard identification was done in real time versus a pre-programmed map.

"ready to begin seeking the signs of past life."

This is a brilliant engineering feat but I don't agree with the premise of that statement.

This is NASA's own mission statement: "The goal of the Mars Exploration Program is to explore Mars and to provide a continuous flow of scientific information and discovery through a carefully selected series of robotic orbiters, landers and mobile laboratories interconnected by a high-bandwidth Mars/Earth communications network."

What you're saying isn't quite true. Perseverance's mission IS to find signs of past life.

See: https://mars.nasa.gov/mars2020/mission/science/goals/

The latter sounds like politically correct wordiness to not piss off the large amount of the planet that believes in intelligent design

Ive always wondered about this "obsession" with finding life specifically.

For some reason I find it unlikely we will find life, and I'm probably wrong. But I also get the feeling from the missions that unless there have been life, there is no reason to go to Mars. I mean there are so many reasons to go there even if we never find signs of life.

This is incredibly impressive. I can't imagine the complexity and the effort it took to make the sky crane maneuver at the end possible.

Mars is dominated by linux machines, ai and machine learning. As I stared at the landing I thought what if it drops into the crater and cannot climb out? At the same time I was really hoping I would see also little antennas poking out from the ground underneath or little martians running around hiding from the new strange visitor. What's the first mission?

Each time I watch one of these big space mission videos I forget about all the joy, happiness, jumping, clapping, screaming, hugging, high fives, and the rest of it after the main event. And every single time it’s awesome :)

I teared up quite unexpectedly as they confirmed touchdown with that "tango delta". Amazing!

The way and the speed by which the sky crane moves away is just like any sci-fi movie, totally unreal [0]

[0] https://youtu.be/4czjS9h4Fpg?t=188

Looks like from terminator 2 or something similar. I remarked to my wife that it looked full on sci fi.

Sky cranes on Mars, HD and 360video, microphones on an suv sized rover.... man... I love living in the future!

Yes! It looked exactly like a B-Grade sci-fi film shot.

Beautiful.

I'm now sitting here wondering where it decided to crash land.

As incredible as this footage is, it's even more mindblowing to realize we've been doing this for 50 years now. We know how to land on mars. Time to do it with people.

We know how to land relatively small things on Mars landing humans will be a much larger craft and because of that a harder task.

But you don't have to worry that much about kicking up a lot of dust (the self-loading meatbags on board can clean your solar panels) so you can just point your thrusters at the ground and play with the throttle a little

It's not just the landing, that's relatively simple and can be mostly done with bigger thrusters on the craft but you have to slow down a lot before you can safely. Right now that's done through a heat shield then a parachute and finally the actual propulsive landing of the SkyCrane. We've done some testing of inflatable shields for the first step but nothing practiced actually in the Martian atmosphere yet and parachutes aren't great for heavier things.

You want to use the other two to slow down as much as possible so you're not hauling extra fuel all the way to Mars. Ideally you'd be using ISRU units to generate your return fuel too.

This method has been used twice, it is nowhere near human rated, hence why its called the 7 minutes of terror. For all the engineering, it has to be perfect or splat

Whats the point of doing it with humans. Robots are getting better every year. Humans not really. Robots will most likely first build an settlement on mars before humans will arrive.

The insight mission, which landed in 2018 has failed to stick a thermometer in the ground over the last 2 years.

A human with a rock/hammer could have accomplished the same thing in an hour, conservatively a day at most.

I agree we should send people as soon as reasonable, but this system is deploying about 1 ton of payload, which isn't going to go very far in terms of life-support equipment (dried rations, maybe... air scrubbers? No.)

The issue with landing people on Mars is that you have to fly them back to Earth.

We have to be prepared to 'die on Mars'.

Anyone can point me to the place where i can find the original video files (that are received from the rover)?

Very surprised this is not trending on YT.

I'm now waiting for the complainers to be all like "But I wanted to see it in VR, this sucks"

Well there is a 360 camera too! Not quite vr but it’s something!

Kudos, NASA. This is why we love you.

Just amazing.

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