Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

SpaceX Crew Dragon Splashes Down After Historic Test Flight

scientificamerican.com

Post reply on HN
Print view View original

51–60 of 152 posts

Re: SpaceX Crew Dragon Splashes Down After Historic Test Flight

#51

Post by perilunar »

ChuckMcM wrote: post #9
Tuna-Fish wrote: post #7

Earlier quoted context omitted.

They are unlikely to do this at this point. The big problem is that while the capsule will be reusable, since NASA killed the propulsive landing for Dragon 2, it now needs to splash down in saltwater and therefore is not considered safe for humans after the first use. This makes Dragon 2:s too expensive for large-scale space tourism. Unless there is suddenly a huge market for this, I think SpaceX would prefer to sell…

I'm not disagreeing with the idea that Musk would shoot for using Starship for tourism, but I also think that I wouldn't put it past SpaceX to continue toward qualifying a reusable Dragon 2. They are already getting good experience (and can experiment with) Dragon Cargo capsule re-use to better understand the impact of salt water landings on their designs. And while it would be hard to find space for the landing stru…

I wonder if they could catch the Crew Dragon with Mr Steven instead of water splashdown? No loss if they miss, and less refurb if they succeed.

Re: SpaceX Crew Dragon Splashes Down After Historic Test Flight

#52

Post by bumby »

XorNot wrote: post #46
ceejayoz wrote: post #40

Earlier quoted context omitted.

https://www.smithsonianmag.com/science-nature/spacex-environ... says: > if the SpaceX’s plan for a rocket launch every two weeks comes to fruition, this amount of carbon (approximately 4,000 tonnes per year) will rapidly become a bigger problem So, that gives us a number... and it's also very weird for the Smithsonian to describe that as a "problem". 4,000 tonnes per year is about a thousand cars worth per the EPA's…

Rockets and the rocket fuel are also in the "easy to substitute" category. They'll never not be hydrocarbons, but significant work has been done on producing rocket-compatible fuels from biological sources, and the marginal increase in cost if you scaled up to industrial production is possibly going to be entirely unnoticeable considering the general purity and refining requirements of anything you load into a spacec…

How do the biological propellants compare in terms of stability? Maybe not an issue for launches, but I'm curious about their viability in satellite thrusters that hang out for years/decades (although this is a digression from the GRG emission concern)

Re: SpaceX Crew Dragon Splashes Down After Historic Test Flight

#53

Post by robbiep »

oldgradstudent wrote: post #50

Could anyone explain what is historic about this test flight? Why is that so different from a bog standard Soyuz or Mercury/Gemini/Apollo?

If you read the article you’d probably be able to work it out, but essentially:

- it marks the return of American human launch capabilities after a several year hiatus from the retirement of the space shuttle

- it is being done on by a private company (with government funding), which is unprecedented

- dragon crew is intended to be reusable (in opposition to Shuttle/mercury/Gemini/Apollo

- the capsule is designed to have inflight abort capability, which is unprecedented and a differentiator from the Boeing effort (previous abort capability came from a ‘towed’ approach (the big pointy thing on top of Apollo) and was only available on the pad, not in-flight, so if something goes wrong during flight the crew is probably buggered)

(Edit: removed Soyuz from list of non-in flight abort capsules)

Re: SpaceX Crew Dragon Splashes Down After Historic Test Flight

#54

Post by [deleted] »

Rapzid wrote: post #30
Tuna-Fish wrote: post #7

Earlier quoted context omitted.

They are unlikely to do this at this point. The big problem is that while the capsule will be reusable, since NASA killed the propulsive landing for Dragon 2, it now needs to splash down in saltwater and therefore is not considered safe for humans after the first use. This makes Dragon 2:s too expensive for large-scale space tourism. Unless there is suddenly a huge market for this, I think SpaceX would prefer to sell…

Any news on this? I was super, super disappointed this mission did have a propulsive landing. I'm just now finding out it was nixed entirely. But that's fine for NASA if they want to pay for a splash down? If somebody else wants to pay for propulsive landing, it's on the table? EDIT: Sounds like a SpaceX driven decision.

[deleted]

Re: SpaceX Crew Dragon Splashes Down After Historic Test Flight

#55

Post by geuis »

jwr wrote: post #38
ChuckMcM wrote: post #4

This is a better article on the recovery than the one I linked from TechCrunch. I would like to reiterate the point made before which is that SpaceX is on the verge of being in a place that no company has ever been before with regard to space. The are on the cusp of having a capsule that they can send into orbit for days and then return to Earth. They already have rockets capable of putting tons of material into ever…

I wonder at which point we will start worrying about the carbon footprint of these launches, though. I didn't do the math, but it seems it might become a global factor once you get to multiple launches per week.

Here’s some numbers I looked up:

Average co2 from a car per year: 4.6 metric tons (https://www.epa.gov/greenvehicles/greenhouse-gas-emissions-t...)

co2 output from a Falcon 9 launch: 440,000kg or 440 metric tons (https://space.stackexchange.com/questions/13082/calculate-fa...)

So a single launch is about 95 cars worth of exhaust a year, give or take.

There were 21 SpaceX launches last year (https://en.m.wikipedia.org/wiki/List_of_Falcon_9_and_Falcon_...)

The number of launches is expect to increase to 30-40 a year (previous source).

Let’s go with 35 launches per year. And remember we’re disregarding all other rockets launches in the world.

35 x 95 = 3325 cars worth of emissions per year.

It’s definitely not great. However it’s such a tiny drop in the bucket overall that it’s not even a rounding error. I think cows produce more methane per year. I’m on mobile at the moment so not gonna look up those numbers.

Rockets get terrible gas mileage.

Re: SpaceX Crew Dragon Splashes Down After Historic Test Flight

#56

Post by geuis »

robbiep wrote: post #53
oldgradstudent wrote: post #50

Could anyone explain what is historic about this test flight? Why is that so different from a bog standard Soyuz or Mercury/Gemini/Apollo?

If you read the article you’d probably be able to work it out, but essentially: - it marks the return of American human launch capabilities after a several year hiatus from the retirement of the space shuttle - it is being done on by a private company (with government funding), which is unprecedented - dragon crew is intended to be reusable (in opposition to Shuttle/mercury/Gemini/Apollo - the capsule is designed to…

Question about the inflight abort: Soyuz has this too. It was used a few months ago when a launch to the ISS went non-nominal. How is the one on Crew Dragon different?

Re: SpaceX Crew Dragon Splashes Down After Historic Test Flight

#57

Post by computerex »

ChuckMcM wrote: post #4

This is a better article on the recovery than the one I linked from TechCrunch. I would like to reiterate the point made before which is that SpaceX is on the verge of being in a place that no company has ever been before with regard to space. The are on the cusp of having a capsule that they can send into orbit for days and then return to Earth. They already have rockets capable of putting tons of material into ever…

> I would like to reiterate the point made before which is that SpaceX is on the verge of being in a place that no company has ever been before with regard to space.

Excuse my ignorance, but what have they done that's so revolutionary? We have been putting people into LEO for decades. What's so groundbreaking about this test?

Re: SpaceX Crew Dragon Splashes Down After Historic Test Flight

#58

Post by robbiep »

geuis wrote: post #56
robbiep wrote: post #53

Earlier quoted context omitted.

If you read the article you’d probably be able to work it out, but essentially: - it marks the return of American human launch capabilities after a several year hiatus from the retirement of the space shuttle - it is being done on by a private company (with government funding), which is unprecedented - dragon crew is intended to be reusable (in opposition to Shuttle/mercury/Gemini/Apollo - the capsule is designed to…

Question about the inflight abort: Soyuz has this too. It was used a few months ago when a launch to the ISS went non-nominal. How is the one on Crew Dragon different?

You’re right. I believe the Soyuz uses two modes, the first is architecturally similar to the Apollo system (ie uses the ‘towed’ mode) whereas the crew dragon has abort built into the capsule.

Re: SpaceX Crew Dragon Splashes Down After Historic Test Flight

#59

Post by luke0016 »

lutorm wrote: post #39
varjag wrote: post #32

Earlier quoted context omitted.

Scrub/repaint every few years? In comparison, splashdown capsules spend maybe few hours tops in the water.

The problem is that, unlike ships, they're generally not designed to be water proof. It's not the exterior that's the problem.

I mean, the crew part of it is water proof, right? It has to be air tight...

I'm guessing there are things on the "outside" that might still have issues?

Re: SpaceX Crew Dragon Splashes Down After Historic Test Flight

#60

Post by simonh »

perilunar wrote: post #51
ChuckMcM wrote: post #9

Earlier quoted context omitted.

I'm not disagreeing with the idea that Musk would shoot for using Starship for tourism, but I also think that I wouldn't put it past SpaceX to continue toward qualifying a reusable Dragon 2. They are already getting good experience (and can experiment with) Dragon Cargo capsule re-use to better understand the impact of salt water landings on their designs. And while it would be hard to find space for the landing stru…

I wonder if they could catch the Crew Dragon with Mr Steven instead of water splashdown? No loss if they miss, and less refurb if they succeed.

Mr Steven is designed to catch fairing halves which weigh just under a metric ton. A Dragon capsule weighs 9.5 tons and can carry up to 7 people or 3 tonnes of return cargo, so it’s from 10 to 13 times heavier than a fairing half.
Post reply on HN