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Crew Dragon Docks with ISS

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Re: Crew Dragon Docks with ISS

#51
post #36

I recall Elon was hoping to get an order of magnitude reduction in cost per launch, but Wikipedia claims it costs $160 million per launch versus the Soyuz price of $76 million per astronaut. That would “only” be a 3x reduction with a crew of seven, but they’ve configured for a crew of four, which is a hair under 2x. I wonder how reuse affects the math, and what they’ll be able to do to lower those prices further. Obv…

Wikipedia is either wrong or out of date but the ratios are slightly worse at 40% cheaper than Soyuz:

https://www.space.com/spacex-boeing-commercial-crew-seat-pri...

> NASA will likely pay about $90 million for each astronaut who flies aboard Boeing's CST-100 Starliner capsule on International Space Station (ISS) missions, the report estimated. The per-seat cost for SpaceX's Crew Dragon capsule, meanwhile, will be around $55 million, according to the OIG's calculations.

> To put those costs into perspective: NASA currently pays about $86 million for each seat aboard Russia's three-person Soyuz spacecraft, which has been astronauts' only ride to and from the ISS since NASA's space shuttle fleet was grounded in July 2011.

Re: Crew Dragon Docks with ISS

#52
post #30

Earlier quoted context omitted.

Incredibly impressive, but you have to take into account both more modern technology, as well as the fact that they were able to build off the shoulders of giants. It is still amazing of course, but I doubt they could've done the same thing during the era of the mercury program, so not really apples to apples comparison.

Sure, there are likely many small advantages that add up. For example, 3 flat panels and a few buttons probably weigh less than a metal panel full of dials, allowing for a better payload ratio. That technology wasn't available during the Mercury/Gemini/Shuttle period for any price.

You can't buy company culture either, but that could have been built 40 years ago

Re: Crew Dragon Docks with ISS

#53
post #15

SpaceX runs basically as a giant R&D program that also happens to accomplish useful things as byproducts of its approach (with the miracle of insurance to cover costs if things get explody). Every flight is data for incremental improvement. If you think of all SpaceX has ever done was try to get to this point, with somewhere around 80 flights on the Falcon 9, but for a variety of mission buyers (NASA, USAF, Commercia…

> We now have the capability to put up another ISS today, resupply it, and staff it, at a fraction of the cost, all with launch equipment made by a single company that started a decade ago. This is the part that's exciting for me. Whether it comes in the form of more space stations like the ISS or a much bigger and reinvigorated ISS, either way is a vital step in the right direction toward making humanity less behold…

I love space exploration like the next guy, but I have a massive fear that a proliferation of space-stations will lead to unpleasant situations. With all its tensions, the ISS has been an amazing tool for soft diplomacy; if we start having country-specific stations we’ll soon end up with nasty arguments. Already we have competing satellites rumoured to have classified capabilities, I hate to think what they could do with manned stations.

I guess it’s inevitable.

Re: Crew Dragon Docks with ISS

#54

Earlier quoted context omitted.

I got it on the first try, but only because I've got 600+ hours of Kerbal Space Program under my belt (where docking is much harder when you consider that docking in KSP entails actually getting to the target and doing it with imbalanced RCS thrusters that I placed on the craft willy-nilly; SpaceX's online docking sim was a breeze in comparison). Trick was to get rotation aligned first, then worry about translation.…

I had a terrible first attempt. Then discovered the same procedure, sort the rotation to 0, then minimise the translation and finally approach the dock. Head down And concentrate on the numbers. I didn’t have the KSP experience to fall back on. I wish they had added a timer as I am now trying for my fastest time.

Yeah, the live stream mentioned the ability to switch between coarse and fine controls, and that ability would be invaluable for a speed run.

Re: Crew Dragon Docks with ISS

#55
From NASA's Mission Updates:

> The Crew Dragon arrived at the station’s Harmony port, docking at 10:16 a.m. EDT while the spacecraft were flying about 262 miles above the northern border of China and Mongolia.

It's hard for me to wrap my brain around this. They seem so far away but 262 miles above earth is about the distance from NYC to DC which doesn't seem far at all.

Re: Crew Dragon Docks with ISS

#56
post #37

They mentioned something about the suit pressure for one of them being lower than expected and asked them to check for "white teeth" on 3 zippers, which they reported seeing on all 3. Can anyone explain what that is?

Sounds like when the zippers are fully closed the white teeth of the zipper should be covered by the seal around the zipper. If any teeth are visible the seal is not complete.

Re: Crew Dragon Docks with ISS

#57
post #40

Watching now.. they were unable to get the "hard line" voice working. VOIP?

Considering how long the ISS has been up there, it could be POTS or something similarly-analog. Dragon→ISS was clear, but ISS→Dragon was not, making me think that maybe there's some wire or connector in the latter direction that's shoddy (and that'd be more common for analog/POTS than digital/VOIP, where such garbling would be bidirectional and/or nothing would be heard on either end).

Then again, I ain't exactly a space telecom engineer, so what do I know? ;)

They've since switched back to RF, so apparently it ain't the end of the world.

Re: Crew Dragon Docks with ISS

#58
post #37

They mentioned something about the suit pressure for one of them being lower than expected and asked them to check for "white teeth" on 3 zippers, which they reported seeing on all 3. Can anyone explain what that is?

I thought maybe they put some sort of chemistry into the zipper to detect gasses and change colors, but I can’t get google to cooperate. And what gas in the suit isn’t already in the cabin?

Re: Crew Dragon Docks with ISS

#59
post #39

So when seeing this I had two questions, one of which I've found the answer to, one of which still remains a mystery. 1. Why only two astronauts? and 2. How much is Crew Dragon costing? For (1), it's stated [1] that Crew Dragon has a capacity of seven astronauts but only 4 for NASA? How does that work? Does that mean the NASA configuration only has 4 seats? I found this [2] saying seats 1 and 4 were empty. Why not 4…

Edited - wrong number of seats for the next mission.

NASA asked SpaceX to change the configuration of the capsule to only support 4 astronauts for two reasons. The first is that they wanted a more mellow Load profile on the passengers in the case of a high-altitude (almost orbit) abort, so they wanted the seats in a different position. The first design had the seats fixed, and the screen pivoting down above them. This design has the seats pivoting, and the screen fixed. It also drops the maximum crew from 7 to 4. I’m not sure if SpaceX will use the larger configuration for their own private configurations.

The other reason is that seven is a lot, and NASA doesn’t plan on sending that many up on a single mission.

Seats 1 and four are empty on this mission. For future missions that only have three they will remove the extra seat. That said, the capsule seems amazingly spacious, for being a capsule.

As far as costing, the contract was written similar to how NASA pays the Russians (though that number is upwards of 87 million per seat right now). SpaceX itself owns the rockets and the spacecraft - not NASA. Think of it as a airline seat.

Finally, the vast majority of cost at this point are not the hardware - but rather the cost of complying with NASA’s testing. Everyone was assuming that NASA would do what they did with commercial cargo, and simply expect the cargo to show up with a minimal number of design reviews. With commercial crew, NASA took a much more proactive approach which led to a complete redesign of the capsule (SpaceX’s original plan was simply to reuse cargo), plus many many many design reviews.

Finally SpaceX has full pricing control right now. SpaceX is running some pretty massive margins (from what I have heard) on everything - but they are flushing all of that money into the goal of getting starship and spaceship and their insane next generation engine up, as well as starlink. They have deliberately only lowered their costs below their competitors, soaking margin for a while.

Re: Crew Dragon Docks with ISS

#60

What's with the gradient shadow? The space station shadow crossed the module, and it was blurry. I thought shadows in space were knife-sharp. The nose-cone shadow was. Its not the stream resolution, is it? Other knife-sharp features were visible. Maybe the space station is fuzzy? Maybe the module material blurs shadows? What am I missing?

Shadows are blurry unless the source is a point. The gradient is the part of the shadow where the source is partially occluded.
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