Discovery's Teardrop | Hacker News Reader

Discovery's Teardrop

jacook.name

153 pointsrunlevel121 comments

This was a beautiful read. I too feel an emotional connection to these great machines and the fantastic people who design, build, and pilot them. To me, our missions into space perfectly captures everything to be admired in Humankind. It represents our inexorable daring in the face of great adversity, it showcases our insatiable curiosity, and, since the the end of the Cold War, it has united people across the globe in the greatest adventure upon which we have ever embarked as a species.

From the ground the moon and the planets seem so far away, so ethereal. Yet just knowing that we have sent people and probes to touch them underlines how obtainable the impossible can be with grit and science, per ardua ad astra. It gives me hope.

I wish that the spirit of international cooperation that has grown around this endeavour will endure over the coming decades and beyond.

Beautiful read of a comment too. I agree entirely and perhaps the mission to Mars will give humanity that hope and connection again.

I'm always surprised on how uneven and hacked together the surface of these shuttles look. I'm pretty sure there's a solid reason for keeping it that way, one would just think it's easier to spot issues on the surface if it's more consistent like the surface of a plane.

I think the unevennes is due to the replacability of the tiles, which is how the tiles end up being of different manufacturing time and degree of wear.

We are all used to the smooth and refined surfaces, assembly, PCBs, etc. of consumer products. Things like the Discovery are unique, there is no real manufacturing process built around them. A passenger plane looks much less 'hacked together', but it's still a bit hacked compared to a Macbook Pro. This is because of the difference in the numbers: 1 vs 1000 vs 1000000 pieces.

Also, this is constantly repaired, updated, etc., not just thrown away and replaced by another one.

Consumer products are designed to be sold where Discovery and commercial aircraft where designed to be used. Occasionally consumer products will evoke that style such pre-linovo IBM laptops. Corporate jet's are the other side of the coin where company's focus on style not just function so dispite low production runs there far sleeker than 140 Boeing 787 Dreamliner out there.

The number on the surface of a new tile is more or less the filename of a CNC gcode program that can create a new tile to a precision quite a bit higher than you can see visually... You can read a tangentially related discussion of this here.

http://www.collectspace.com/ubb/Forum14/HTML/000534.html

There's at least 20K HSRI "model numbers" and over the years probably many more as revisions were made, they made lots of Q+A test pieces and there were many revisions and lots of repairs and there's a lot more than just black HRSI tiles, I'd estimate somewhere in the realm of "way more than 10M tiles" were made over the years. The hotter they get the smaller and thicker they have to be, something about differential thermal expansion stresses or something.

The TPS as a whole was quite a technological accomplishment.

Could very well be functional. The rippling looks to me similar to the rippling and unevenness of the SR-71, which wasn't smooth because a smooth surface would be less stable at speed.

Actually, portions of the SR-71 skin were corrugated, much like the older (and much slower) Ford Tri-Motor, because the high temperatures of Mach 3+ flight caused the skin to expand and contract dramatically throughout the flight profile. This corrugation was actually against the wishes of the aerodynamicists, who would have preferred a smooth surface.

http://en.wikipedia.org/wiki/Lockheed_SR-71_Blackbird

Yep, and those planes leaked fuel like a sieve until the skin contracted and smoothed into the proper shape mid-flight.

The tiles I've seen (including physically touching) have been smooth as a countertop, at least when new.

I believe this pix was taken in the post-FIB era. Flexible insulation blanket. Not all tiles could be replaced by FIB but some could and were. I imagine the heat load was not very high in those positions, so FIB makes sense. And I know FIB looks exactly like the wavy blanket quilt look you're talking about and is seen in the pix. FIB had another name which I forget. The nomex based "frizzie" (FRSI?) looked less quilt-y, more like a prom dress fabric, well, kinda. I don't see anything I recognize as frizzie in the linked pix. Frizzie looks like the inside layer of a firemans coat, which also probably doesn't help describe it very much, yet, there it is.

TLDR is that wavy tile is not a tile, its a quilt.

Most people know the engines were under continuous development for practically the whole program; well, so was the heat shield system. I can't be bothered to look it up and it doesn't matter anyway, but I don't think the same TPS configuration ever flew more than three or so times in a row without some new idea being tried, at least in the early decades. Continuous integration.

Personally I always suspected we'd lose more orbiters due to continuous integration fiascos than mechanical damage. Then again they spent a lot of money on research, Q+A, and experimentation so what would be a disaster in a typical IT shop works pretty well in aerospace.

On reentry the tiles burn and degrade, and thus had to be tested and replaced on Earth if necessary. They are all numbered with serial numbers that uniquely identifies them and their location on the surface of the shuttle [1]. Like a real life hash table ;)

Smaller tiles are easier and cheaper to replace, and thus the uneven look.

[1] http://artifacts.nasa.gov/tile_serial_numbers.htm

I was curious about this too and asked on Reddit, which got a variety of answers (and good terms to search for!) if you're interested in finding out more: http://www.reddit.com/r/askscience/comments/26idyd/why_weren...

Nice. Now I want a font geek to look into why Discovery's name is done is a nice Helvetica-like typeface but the final "y" has that odd kink at the end of it.

That’s just perspective and topology playing tricks on you.

It’s just extremely boring Helvetica. Here’s the shuttle from another perspective (with “Discovery” in Helvetica Bold added for reference): http://i.imgur.com/kRxj2vj.jpg

Here's another even closer pic.

http://darkroom.baltimoresun.com/wp-content/uploads/2012/04/...

That is definitely not Helvetica. The dead giveaway is the 'e', the crossbar is too high. If my eyes aren't fooling me, the terminators on the 'c' aren't parallel either. If that's not enough, the 'r's terminal is too long.

Yeah, your right, it imitates Helvetica but doesn’t seem to be quite it. I wonder why. Maybe there is some mundane explanation, though, since there must be hundreds of Helvetica clones out there.

Good picture. It's like it starts with a solid font D-I-S-C and then things get all funny. The V is too thick as well.

As an aside, I would highly recommend making a trip out to see Discovery if you are ever in the DC area (the Udvar Hazy Center is just a few minutes' drive from Dulles airport). They let you get remarkably close to the shuttle (close enough to touch, although you shouldn't do so). Also, they chose not to clean her up very much when they installed her (as is somewhat evident in the linked photos). As a result she retains all of her scars from usage and re-entry, which I think makes her feel both much more real and fantastical.

Fascinating read. Too bad that the conclusion is still a hypothesis.

Also, this is the first time that I have taken a close look at the surface of the shuttle, and as @dewey noted, I too found it to be very uneven and blocky. From a distance, they look reasonably smooth.

My grandfather helped design the tiles used on the space shuttle. Every time I see a picture of one of the shuttles it brings back good memories of him.

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