SpaceX successfully launches two humans into orbit • Hacker News Board

Re: SpaceX successfully launches two humans into orbit

#611

Post by simonh » Sun, May 31, 2020, 6:21 AM UTC

mumblemumble wrote: post #558

wongarsu wrote: post #511

Earlier quoted context omitted.

On the ISS you can produce higher quality optical fiber than on earth [1]. A demonstration fabrication unit is already on the ISS, and NASA has recently published prices for using the ISS for commercial tasks such as this. I suspect many other manufacturing methods can also benefit from zero gravity, and as launch costs drop more of these will be explored. 1: https://upward.issnationallab.org/the-race-to-manufacture-…

It's interesting to think about that from the other side, too. Just delivering the raw materials to the manufacturing facility would cost ~$3000/kg (assuming rock bottom SpaceX prices). Based on some loose googling, I think that 1kg of raw material would yield only something on the order of 100m of cable. It looks like a typical 100m fiber optic patch cable retails for about $60. So, there's clearly a lot of value to…

> I think that 1kg of raw material would yield only something on the order of 100m of cable.

That sounds like you’re including the weight of the whole final cable, including yarn strengthening members, plastic shroud and sometimes a braided metal shield layer. Only the glass fibre itself actually needs to be manufactured in space and is usually on the order of a kg or so per km.

Re: SpaceX successfully launches two humans into orbit

#612

Post by seesawtron » Sun, May 31, 2020, 6:28 AM UTC

When was the last time humans were launched into space? It happens all the time doesn't it? Astronauts going to ISS in shifts throughout the year.

Re: SpaceX successfully launches two humans into orbit

#613

Post by avmich » Sun, May 31, 2020, 6:32 AM UTC

rtkwe wrote: post #607

avmich wrote: post #20

Earlier quoted context omitted.

Buran had non-toxic components for RCS. Kliper was planned with non-toxic RCS. Soyuz spacecraft at least has non-toxic components for capsule RCS, so when the capsule lands, it doesn't need to be approached in a chemical protection suit. It's not a question of choices - there are choices. I suspect it's a question which is considered less important so far, so SpaceX didn't pay that much attention to it, considering t…

From a quick search their main RCS is still a dimethylhydrazine which is quite toxic. They're just on the engine part of the craft instead of on the capsule so it doesn't come down to Earth. https://en.wikipedia.org/wiki/KTDU-80#Pneumatic_Pressurizati... http://www.russianspaceweb.com/soyuz-ms-kdu.html

Right, but at least the capsule, which goes through atmosphere and keeps people inside, doesn't have the toxic substance.

It's not saying Soyuz is perfect, or near that. It's about Crew Dragon - the spacecraft could use already existing ways to avoid toxic materials in operations, and it wasn't done. And it's hard to do after the design is complete. So we can reasonably hope for the next spacecraft to be better - fortunately trying to make Starship refuelable on Mars and limiting propellants to LOX and methane works for the goal of reducing toxicity.

Re: SpaceX successfully launches two humans into orbit

#614

Post by avmich » Sun, May 31, 2020, 6:35 AM UTC

sephamorr wrote: post #319

avmich wrote: post #20

Earlier quoted context omitted.

Buran had non-toxic components for RCS. Kliper was planned with non-toxic RCS. Soyuz spacecraft at least has non-toxic components for capsule RCS, so when the capsule lands, it doesn't need to be approached in a chemical protection suit. It's not a question of choices - there are choices. I suspect it's a question which is considered less important so far, so SpaceX didn't pay that much attention to it, considering t…

Soyuz still uses UDMH and nitrogen tetroxide as its propellants. It simply jettisons the propulsion module before reentry so the reentry module has no thruster system and therefore no (toxic) fuel. With the return of a SpaceX vehicle, the recovery crew don't have suits on, that would be very unwieldy at sea, and they would just back off if trace gas detectors measure a toxic leak.

> Soyuz still uses UDMH and nitrogen tetroxide as its propellants.

Right, but at least Soyuz doesn't have them in the returning capsule. Crew Dragon could be just as good in this aspect, but unfortunately isn't. So when moving the capsule from the sea the team has extra dangers.

Re: SpaceX successfully launches two humans into orbit

#615

Post by ralusek » Sun, May 31, 2020, 7:09 AM UTC

antepodius wrote: post #586

shrimp_emoji wrote: post #526

Earlier quoted context omitted.

Ironic since the Culture is anti-capitalist. xD

So is spacex. It's a dictatorship.

All the people forced to buy contracts with them. All the people forced to work with them. Pure. Tyranny.

Re: SpaceX successfully launches two humans into orbit

#616

Post by raverbashing » Sun, May 31, 2020, 7:09 AM UTC

hprotagonist wrote: post #291

jp_sc wrote: post #277

Earlier quoted context omitted.

- International travel (anywhere in the world in less than two hours) could be one of those things. - Asteroid mining

>in less than two hours plus or minus 48, depending on the clouds today.

The launch window limitations were due to the ISS orbits.

For other destinations or uses, the launch windows might be more flexible or not be an issue at all.

Re: SpaceX successfully launches two humans into orbit

#617

Post by ralusek » Sun, May 31, 2020, 7:14 AM UTC

linkmotif wrote: post #492

ChuckMcM wrote: post #86

It is hard to convey how "sustainable" this feels to me. For the first time, humans have gone into orbit in a spacecraft that was designed from the ground up to be a commercial venture. All of the NASA missions prior to this have an ambience of "uneconomical but useful". Even the shuttle, which was supposed to be this cost effective space truck, turned out to be not even close. And the last thing I'm feeling is the a…

I don't understand how SpaceX is "commercial." As I understand it, they exist because the US Government wants to have a space program. Yes, they can launch satellites, but how many for-profit non-state entities can use these things? It seems like SpaceX is possible because there are governments out there with money to burn.

Starlink, for one.

Re: SpaceX successfully launches two humans into orbit

#618

Post by TeMPOraL » Sun, May 31, 2020, 7:16 AM UTC

noizejoy wrote: post #522

jacobush wrote: post #465

Earlier quoted context omitted.

A machine can not tell us how it felt to be there, and write a poem about it.

but a good sci-fi writer can

The sci-fi writer does it in hopes one day a historical fiction author will be able to.

Re: SpaceX successfully launches two humans into orbit

#619

Post by londons_explore » Sun, May 31, 2020, 7:26 AM UTC

sargun wrote: post #610

mumblemumble wrote: post #558

Earlier quoted context omitted.

It's interesting to think about that from the other side, too. Just delivering the raw materials to the manufacturing facility would cost ~$3000/kg (assuming rock bottom SpaceX prices). Based on some loose googling, I think that 1kg of raw material would yield only something on the order of 100m of cable. It looks like a typical 100m fiber optic patch cable retails for about $60. So, there's clearly a lot of value to…

So, no idea the cost of O-O amplification or O-E-O these days, but it's expensive. You have to run power (usually there's power with the optics), and the bigger problem is real estate (At least in urban areas). 100x lower signal loss would do away with most of these. For example, the MAREA ( https://en.wikipedia.org/wiki/MAREA ) undersea cable is 6,600 km long. Current optical fiber requires repeaters every ~100km. I…

Presumably lower loss also means more bandwidth when background thermal noise becomes the limiting factor.

Re: SpaceX successfully launches two humans into orbit

#620

Post by osamagirl69 » Sun, May 31, 2020, 7:28 AM UTC

mumblemumble wrote: post #558

wongarsu wrote: post #511

Earlier quoted context omitted.

On the ISS you can produce higher quality optical fiber than on earth [1]. A demonstration fabrication unit is already on the ISS, and NASA has recently published prices for using the ISS for commercial tasks such as this. I suspect many other manufacturing methods can also benefit from zero gravity, and as launch costs drop more of these will be explored. 1: https://upward.issnationallab.org/the-race-to-manufacture-…

It's interesting to think about that from the other side, too. Just delivering the raw materials to the manufacturing facility would cost ~$3000/kg (assuming rock bottom SpaceX prices). Based on some loose googling, I think that 1kg of raw material would yield only something on the order of 100m of cable. It looks like a typical 100m fiber optic patch cable retails for about $60. So, there's clearly a lot of value to…

For the time being, they are targeting specialty applications where it is not uncommon to charge in excess of $1000 per meter even for normal earthly fibers.

For scaling up, if one uses the smallest commercial fiber standard (80um diameter cladding--they would put the buffer and whatnot on after it comes back to earth) the mass of the fiber is only 53grams/km so using your $3000/kg the cargo cost is only $0.16/meter which seems pretty palatable to me.