SpaceX To Refly a Dragon Cargo Spacecraft (arstechnica.com) 41
Thelasko writes: Tomorrow's scheduled resupply mission to the International Space Station will mark the second time its Dragon capsule has visited the station. Ars Technica reports: "This particular Dragon spacecraft was sent to the International Space Station in September 2014, and it delivered nearly 2.5 tons of cargo to the orbiting laboratory. The Dragon returned to Earth about a month later, splashing down into the ocean. It is not clear how much processing SpaceX has had to undertake to ready the spacecraft for its second flight to the station, nor has the company released a cost estimate. It also had to manufacture a new 'trunk,' the unpressurized rear section of the vehicle, and solar panels."
s/time its Dragon/time this particular Dragon/ (Score:5, Informative)
Dragon has flown to ISS on multiple occasions but this will be the first time that a Dragon capsule that has previously flown to ISS is being launched for a second visit.
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I'm curious to see if they use the Super Draco thrusters to land the Dragon capsule on land or one of the barges. That is, if this particular capsule is even outfitted with the thrusters.
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You'll probably have to wait for Dragon 2 to see that and Space-X will almost certainly perform the first test with with another dummy payload like the wheel of cheese they put in the first Dragon before Nasa accepts it's use for returning anything from ISS.
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No, this is a cargo Dragon, and has no provision for propulsive landing.
The Dragon v2, or Crew Dragon, will fly for the 1st time later this year, but will use parachutes for the initial test.
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The Dragon capsule (aka Dragon 1 capsule) doesn't have Super Draco thrusters. It is only capable of parachute splashdown at sea.
The Dragon 2 capsule is the one with Super Draco thrusters. First flight of a Dragon 2 capsule is currently planned for November 2017.
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The Space Shuttle required extensive refits after every launch, with each refit costing more than a disposable Falcon 9 launch. It was an interesting idea ruined by design by political committee.
And there have only been four total X-37B launches, with both vehicles having been launched twice. Hardly routine, though hopefully it will become so.
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This reads like an old UNIX Fortune entry.
Tomorrow = actually today (Score:2, Informative)
Story was written yesterday. The launch is today (Thursday) at 21:55 UTC.
Pre-launch NASA briefing (Score:5, Informative)
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Because Dragon still needs them as the onboard batteries are not of sufficient size to last from ISS uncoupling all the way down to splashdown.
Because adding them to ISS would take more work than their marginal addition would bring.
Ran the numbers: (Score:2)
7 came in first, with 1 coming up fast at the end to make it a race. 5 and 8 were neck and neck, with 8 taking third by a nose.
Re: why do they ditch the solar panels? (Score:2, Informative)
It takes 3-4 days to reach the ISS (due to phasing). That's far from a trivial amount of time to run off batteries.
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https://en.wikipedia.org/wiki/... [wikipedia.org] says the solar panels have a peak production of 4kW, and in orbit they can probably pull peak production pretty continuously.
And while I couldn't find anything with a quick search on the time between separation and landing, this press release http://www.spacex.com/sites/sp... [spacex.com] says it took about two days between launch and docking with the space station, so it might not be completely unreasonable to expect something similar for the return.
As for solar panels versus batteries
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> that would add up over time.
Not as much as you'd think - things would very rapidly get so cluttered that you couldn't effectively add any more panels - there's only so much surface area on the ISS perpendicular to the sun, and none of it is designed for the ready addition of solar panels, and orbital construction work is extremely difficult and dangerous. Even in the best case scenario, time spent in EVA significantly increases the astronauts radiation exposure.
I agree that it would be nice to be re-u
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Add to that that that the solar panels are not designed to be easily removed from Dragon / installed to ISS.
The replacement of the optical module to allow Hubble to be saved wasn't designed to be changed in orbit either so it's possible but then, the Hubble operation took months of preparation and billions of $$$. The marginal addition of a few % of electrical generation that would need major ESA work every Dragon launch isn't just worth it.
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True, though in fairness it wouldn't need major work after *every* EVA, you could save up the panels until you had enough to be worth installing as a batch.
And you could relatively easily decrease the incremental labor as well - assuming the solar panels are designed to be easily attached to the Dragon as well as detached, you could add one or more "branches" to the ISS outfitted with numerous compatible easy attachment points. That would of course require a single more substantial project to build, launch
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I wonder why they don't transfer the solar panels to the space station and do reentry on internal batteries only? Surely the station could use them as additional, or at least spare, panels.
I think we can bet that if SpaceX builds a space station, it'll have solar cells with modular connectors on the edges, and each supply vessel can have its detached and added to the space station.
But ISS was designed by NASA, which has several conflicting priorities.
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But ISS was designed by NASA, which has several conflicting priorities.
That is literally the most polite way I've ever heard used to refer to the morass and earmarking that is NASA's budgeting and operations.
Will we find out how much processing for reuse? (Score:4)
As people have pointed out, the various Space Shuttles were reused quite a few times and the X-37 has flown multiple times. They both require significant refurbishment before they could be flown again - the Space Shuttle required basically a reskinning of the thermal protection tiles and for the X-37 it sounds like the tiles are good, but it requires significant refurbishment inside the spacecraft after it's long stays in orbit. It would be interesting to see how much work is required on the Dragon (and SpaceX hasn't really explained what needs to be done to refly a Falcon booster).
The problem is, if SpaceX has very efficient systems for turning around Dragons and Falcon boosters then they may want to keep it secret to minimize competition. On the other hand, if they have a very poor process, they want to keep it secret to give the appearance that they know what they are doing.
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We'll probably find out eventually, by which time the process will have changed anyway. They're still evolving it. At this point they will be doing massive amounts of inspection work both to ensure flight readiness, and to determine what is actually necessary for refurbishment.
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Arguably they're still in beta-test, at least as far as the technology to return the various crafts to the planet in a reusable state is concerned, and it sounds like they're well aware of that.
This arguably is a long-term game. We've been putting stuff into space in one form or another for 60 years, and up until now the vehicles were either disposed-of or else required so much refurb that perhaps disposable vehicles would have made more sense financially. The company that manages to re-fly and thus reduc
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Reusable rockets could see far-reaching uses. Imagine if the technology scaled to allow for suborbital point-to-point flights for passenger livery, where the rockets could return to their air/spaceports for refuel/reuse, while the spaceliner glides to its destination port in a fraction of the time it takes to make such long commercial flights.
From what I understand the atmospheric shell where you get any significant updraft as a plane is pretty thin compared to a rocket trajectory and if you try to skim the surface you'd get massive atmospheric resistance during launch and still not all that far gliding. So you'd end up more like a sub-orbital rocket and suffer all the problems of re-entry with a heat shield.
not much work needed for reuse. (Score:2, Informative)
Late 2017 or early 2018 they are aiming to re-fly a falcon within 24 hours of landing, with no refurbishment (just refiling the tanks)
The first one that was reflown had much more extensive work done on it (all components that can wear were replaced)
The grids used to steer during re-entry are currently aluminum and replaced after each flight. They are going to replace them with titanium (at which point these will be the largest titanium castings anyone knows of in the world from what I've heard), at which po
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Thank you - I knew about the aluminum steering grid issue, I didn't know they had a goal for such a quick turnaround.
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https://en.wikipedia.org/wiki/... [wikipedia.org]
There are only two X-37s, and they've each only been launched into orbit twice. Technically that is "multiple times", but not nearly so many as the term suggests - only one flight-proven refurbishment each.
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According to Koenigsmann, SpaceX technicians replaced several items that were exposed to salt water after splashdown, such as batteries and the capsule’s heat shield. But the hull, thrusters, harnessing, propellant tanks, and some avionics boxes are original, he said. “I can tell you the majority of this Dragon has been in space before,” Koenigsmann said.
Source [spaceflightnow.com]