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

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

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.

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.

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.

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.