2428: Mars Landing Video

Explain xkcd: It's 'cause you're dumb.
(Redirected from 2428)
Jump to: navigation, search
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.


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 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. This comic is set at that press briefing and was published shortly before NASA, either unaware of Randall's threat or recognizing that it was not serious, went ahead and hold the briefing in real life. "Full-speed" here means that the video was captured at a frame rate high enough that it looks continuous when played back, as opposed to low-frame-rate imagery that looks jerky when played back.

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. As there is only one full speed video of a Mars landing, that makes the video the best one as well as the worst one. Randall, who has often been banned from conferences, has apparently 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 (a prior case of the latter is possibly why the former is currently active).

He follows up with the question of whether NASA is planning to make a worse Mars landing video, which is silly because people generally don't intend to make something worse.[citation needed] 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. Although this is merely a consequence of the fact that it is the only full-speed video of a Martian landing so far, the fact that it is technically true, as well as the way that Randall phrases it, makes it look embarrassing for NASA. The tendency of Randall (the character, not the real-life person) to make rude, embarrassing, and otherwise unwelcome comments is probably why he has been banned from NASA's press briefings, as well as all those conferences.

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 that can lower or raise objects similarly to standard cranes. Specifically, one of these was used to land the Perseverance rover three days before. On Earth one might 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 ironic, especially since NASA's security was totally unprepared to stop him from using this method - a method NASA developed - to crash the press-briefing.

The title text refers to the 11-minute communications delay (one-way; 23-minute delay round-trip) between Mars and Earth, due to the speed of light and the distance between the planets at the time of the rover's landing. The 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 period in which he can ask whatever questions he likes before NASA can respond. This would only make sense if the conference he was crashing was on Mars and they were waiting for his questions here on Earth, or vice versa and plays on the ambiguity of the expression "Mars briefing", which can mean both a briefing about Mars and a briefing taking place on Mars.


[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 off 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.

comment.png add a comment! ⋅ comment.png add a topic (use sparingly)! ⋅ Icons-mini-action refresh blue.gif refresh comments!


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)

A "sky-hook" is (according to the OED), "An imaginary device for or means of suspending something in the sky." (first citation 1888). (This is something I have heard of before). I thought that Randell might have meant that imaginary device, but then discovered that he was just referring to the Mars landing device - shame - sky-hook might have been better! Kulath (talk) 20:21, 27 February 2021 (UTC)

Not sure that would have been an improvement. Sky-hooks apply to every situation/no situation in particular (or perhaps best for a talk on the historic Fulton Surface-To-Air Recovery System), and makes little sense in intruding into a NASA presser. This was a "they used a sky-crane, I shall use a sky-crane!" situation. That's definitely apt. (Maybe he can bring up actual sky-hooks when NASA is unveiling some plan for a momentum-exchange tether to use for orbital lofting..?) 22:15, 27 February 2021 (UTC)

Does anyone know why this is incomplete?[edit]

Without information, nobody knows which part needs fixing. If anyone knows why this is incomplete, please post the reason here. If nobody can provide a satisfactory answer, maybe we should consider removing the incomplete tag.--Quillathe Siannodel (talk) 14:37, 25 March 2021 (UTC) EDIT: I am posting this exact same text on other comics of questionable incompleteness. It's not spamming, it's a conscious attempt to clean this category up made by a real live human.--Quillathe Siannodel (talk) 14:37, 25 March 2021 (UTC)