2428: Mars Landing Video

Explain xkcd: It's 'cause you're dumb.
Revision as of 14:52, 23 February 2021 by Kynde (talk | contribs) (This is not a conference, so he is not banned from yet a conference It is a pres briefing)
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Mars Landing Video
The best part of crashing a Mars briefing is you can get in a full 11 minutes of questions before they can start to respond.
Title text: The best part of crashing a Mars briefing is you can get in a full 11 minutes of questions before they can start to respond.


Ambox notice.png This explanation may be incomplete or incorrect: Created by THE WORST SKYCRANE. Please mention here why this explanation isn't complete. Do NOT delete this tag too soon.
If you can address this issue, please edit the page! Thanks.

Three days before this comic was published, NASA successfully landed a new rover, Perseverance, on Mars, this was also the subject of the previous comic 2427: Perseverance Microphones.

This comic is set at the press briefing where a video of the landing (a first ever) is presented, and was published shortly before this happened in real life.

This comic plays on the fact that if there is only one of something in a set, that one thing is the most/least in that set by lack of comparison. As there is only one full speed video of a Mars landing, that makes the video the worst one. Randall, who has often been banned from conferences, has also been banned from NASA's press briefings. So he decided to crash the conference (literally, see below) solely to ask the question, "is this then not also the worst video ever", flouting his ban and embarrassing NASA.

He follows up with the question if NASA is planning to make a worse Mars landing video, which is silly because people generally don't intend to make something worse. However, because this video is the worst full-speed video of a Martian landing by virtue of being the only full-speed video of a Martian landing, it is likely that if enough full-speed videos of Martian landings are made in the future, this video will not be the worst forever.

Judging by the sound effects, Randall has chosen to literally crash his way through the roof, using a "skycrane" — a general term for aerial vehicles, similar to standard cranes, that can lower or raise objects. Specifically one of these was used to land the Perseverance rover three days before.

This comic was published shortly before a NASA press briefing that showed, as mentioned in the comic, the first ever full-speed video of a Mars landing. On Earth one would likely use the Sikorsky S-64 Skycrane helicopter, while NASA used a custom-built skycrane delivery system for the Perseverance rover. Randall deems using a skycrane to crash a conference about a skycrane very ironic, especially since NASA's security was totally unprepared to stop him from using this particular method to crash the press-briefing.

The title text refers to the 11-minute (one-way; 23 minutes round-trip) communications delay between Mars and Earth, due to the speed of light and the distance between the planets at the time of the rover's landing. Perseverance mission control must wait this long before they can even begin to respond to anything that happens to the rover, which Randall here twists into an 11-minute delay before they can begin to answer his questions allowing him to ask questions for 11 minutes before they can intervene. This would of course only make sense if he was crashing the conference at Mars, and they were waiting for his questions here on Earth. And that would not make sense anyway. Also since the round trip is 23 minutes, he would not hear any response from them until 23 minutes after he began asking questions.


[Hairbun is standing, arms spread out, on a podium in front of a lectern. There is a "Crash" on the top right of the panel with several lines around to indicate the position, and an of panel voice coming from there. As indicated in the caption below the voice is from Randall.]
Hairbun: We're excited to share the first ever full-speed video of a Mars landing.
Sound: Crash
Randall (off-panel): Doesn't that mean it's also the worst ever full-speed video of a mars landing?
Randall (off-panel):Do you expect that record to stand forever, or is NASA working on a worse one?
[Caption below the comic]:
NASA tried to ban me from their press briefings, but ironically their security was totally unprepared to deal with a skycrane.

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When I saw "full speed landing" I thought it meant failed landing, as in a 2000-mph rover landing. --Char Latte49 (talk) 19:53, 22 February 2021 (UTC)

I thought that too. Elektrizikekswerk (talk) 07:55, 23 February 2021 (UTC)
Are you talking about lithobraking? -- Hkmaly (talk) 02:09, 24 February 2021 (UTC)
Yes, but without the airbags ;) Elektrizikekswerk (talk) 07:37, 24 February 2021 (UTC)

Why the specification that the video is full-speed? Did we already have slow motion video of a Mars landing? Bischoff (talk) 09:35, 23 February 2021 (UTC)

full-speed in the context of video usually means 24 to 30 frames per second(FPS) (or 60 fields if interlaced) and slow motion is anything 60fps or faster, but it is the ratio of recording speed to playback speed that matters. Record at 120fps and play back at 30 and you get smooth 1/4 speed slow motion; record at 24fps and play back at 6 and you get a jerky almost stroboscopic effect. The NASA press briefing included a “1/3 speed” video, which implies 75 to 90fps, but for all I could tell they might have simply slowed down the playback of the “full speed” feed. I suspect that prior landings had at best a handful of images that would constitute a playback frame rate of less than 1 per second, and thus would best be described as time lapse. 12:13, 23 February 2021 (UTC)
I've not been keeping track of what was released when, but it was essentially "a series of stills" (i.e time-lapse, when compiled into a short video) for most(/all?) recent missions. Sometimes at the speed of capture (low-FPS playback), sometimes at a better speed of comprehension (sped up), sometimes possibly a mix (the comet impact/sampling video, I think had notes about it actually being five seconds of contact, but only usable pictures were edjted into the 'flickerbook' view).
The problem these days is probably more the bandwidth to send captured data back. Hardware and storage are probably capable, these days, as long as all vital science/navigation information can also be bit-shifted alongside the interest-raising videos more tuned to publicity. But once settled down, and while everything mission-critical is now being assessed back home it can probably trickle some HD video back (ready to re-use the memory space, shortly) to let them entertain the masses. ;) 13:07, 23 February 2021 (UTC)
Maybe some of this information about the "full-speed"ness of the video belongs in the main explanation body? --Markjreed (talk) 14:22, 23 February 2021 (UTC)

"The comic plays on the fact that if there is only one of something in a set, that one thing is the most/least in that set by lack of comparison." This is the math perspective. There are grammarians who insist that you shall not use superlatives* if there are less than three examples. When the math teacher calls the English teacher "My dearest wife" she slaps him and files for divorce on the grounds of trigamy.

  • OTOH both view accept that comparators must apply to exactly two examples. 17:32, 26 February 2021 (UTC)