The Parachute Message | Hacker News Reader

The Parachute Message

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115 pointssunraa25 comments

The British company that made the parachute's fabric has a great little piece about it here [0]. In 15 years they went from a demo at a symposium in the US to a canopy that could achieve a 98% reduction in the re-entry speed of a massive payload.

[0] https://www.heathcoat.co.uk/perseverance-landing/

I was one of the people who went viral on twitter and was interviewed by the NYT for posting the solution. [1, 2] It was really neat to see people all over the world come together to solve this puzzles in <6 hours. [3]

[1] https://twitter.com/adithya_balaji/status/136402008259946087...

[2] https://www.nytimes.com/2021/02/24/science/nasa-mars-parachu...

[3] https://twitter.com/steltzner/status/1364076615932645379?s=2...

JPL has a history of hiding messages like this. One of the rovers leaves tracks that spell "JPL" in morse code. I think it's all kind of fun.

Genuinely one of my favorite trivia questions about curiosity: https://www.scientificamerican.com/gallery/curiosity-rover-m...

A PDF of slides, inside a git repo, and concluding with a picture from - and a non clickable link to - a tweet from another person, seems like an awfully peculiar way to share content.

If you think parsing that sentence is insane: exactly.

Here's where the coordinates on the outer rim point to (For the lazy) https://goo.gl/maps/MCqYxngeQLJRMNeK7

DARE MIGHTY THINGS

Interestingly, their hands were somewhat tied when it came to coordinate system precision [1] because they had eight 7-bit words to encode with data.

They couldn't say "34.20 N 118.17 W", which would indicate they're talking about the whole campus and industrial park it's in, because that's only 6 words.

Instead, by defining it to a precision of one arcsecond, they imply that JPL is located within the 30-by-25-meter rectangle [2] between 34°11'58.5"N 118°10'31.5"W and 34°11'57.5"N 118°10'30.5"W, which is basically a turnaround and associated parking lot island.

[1] Relevant XKCD: https://xkcd.com/2170/ [2] Rectangular [3] because the circle around the earth at higher latitudes is smaller than the circle at the equator. [3] OK, approximately rectangular. It's rectangular on a Mercator projection map!

The coordinate square contains a lot of roadway, yes, but it also contains the front door to von Kármán Auditorium, which is where many of the public-facing lectures and press conferences are held. In other words, that square is basically the front door to the whole lab.

official word: https://www.jpl.nasa.gov/images/mars-decoder-ring

Was it just me who decided not to open a random PDF from GitHub?

Just you.

A little disappointing actually! I thought the pattern was a clever way to capture the status of the parachute in the event of failure, so if all they got was a garbled low-res image before the lander crashed to the surface they could deduce which section failed. Alas, it was just an easter-egg..

> ... just an easter-egg ..

Not true, according to OP:

> Allen Chen revealed that there was a code hidden in the parachute, as well as the markings being useful for camera alignment.

Asymmetrical markings also allowed for measurement of parachute rotation during the operation.

I wonder how much more expensive was it to create the parachute with the code.

Probably not a lot. I believe they needed to create a pattern on the parachute anyway for tracking orientation and inflation.

Almost everything in these missions is a one-off order built to unique specifications.

The color of the parachute? It was probably not even a line item. As a sibling comment pointed out, they'd still would've colored it in a way that helped with tracking and orientation.

Most places that do custom printing for Mars-ready parachutes give you a nice 10% off coupon if you sign up for e-mails, or they might have snagged a Black Friday deal.

Never understood downvotes on questions or on economics. The cost of something affects how well it will scale. This is like downvoting a question about performance specs. Cost is a performance spec that determines scaling.

Subtle play of the classic HN "but does it scale?" joke. As if someone is concerned about how well martian parachute assembly processes scale :D

Elon cares.

I don't think he plans to use parachutes, but I would not be too surprised if it would be more efficient to get some non-fragile supplies down on parachutes and airbags, but that would be a very long way out.

I personally saw it as a low-effort question, which could also indicate someone trolling, or trying (and failing) to make a joke. When you've spent billions of dollars on something, dyeing the fabric of your parachute in a particular pattern is obviously such a tiny tiny tiny tiny fraction of a percent of your budget that it's entirely irrelevant.

If you were planning on building these for something where the cost of the parachute would actually matter, and need to do so at scale, perhaps you'd switch to a single-color parachute (with simple orientation/tracking markings). This discussion isn't really interesting at all.

When you start adding tiny tiny tiny fractions to a multi-million dollar project because, come on it is a tiny tiny tiny fraction, and everybody in the team starts doing it in their module/subsystem because, it is a tiny tiny tiny fraction, it starts adding up... that is really what my rhetorical question was.

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