
SpaceX's Dragon cargo ship splashes down in Pacific - dnetesn
http://phys.org/news/2016-08-spacex-dragon-cargo-ship-splashes.html
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ufmace
> SpaceX's Dragon is the only cargo carrier in use that can return gear to
> Earth.

Don't they mean the only American cargo carrier? I thought the Soyuz was the
only capsule ferrying Astronauts to and from the station, at least until the
Commercial Crew program gets to that point.

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dkbrk
Technically Soyuz _can_ return a small amount of cargo, but it is extremely
weight and volume limited. I couldn't find a precise figure, but it looks like
it can return at most 50kg or so of cargo, in addition to crew.

Dragon can return about 2500kg in total (though it is quite volume limited),
and has special facilities such as cargo racks that can support, for example,
a powered freezer to hold scientific samples requiring such facilities.

None of the other operational vehicles -- Progress, Cygnus or HTV -- have any
cargo return capability.

So the quote is correct in two respects: firstly, Soyuz isn't generally
considered a "cargo vehicle"; and if you expand that definition, Soyuz can
only carry an extremely small amount of a limited subset of possible return
cargo that does not include the most interesting payloads such as frozen
biological samples.

When the Commercial Crew vehicles become operational in the next couple of
years they will also provide some cargo return capability, but that isn't
their primary purpose and will be fairly limited under most circumstances.

The second round of the Commercial Cargo program -- CRS2 -- has selected
Sierra Nevada Corporation's Dream Chaser in addition to Dragon and Cygnus.
Dream Chaser is a spaceplane that will provide substantial cargo return
capability by landing on a runway. This will subject the payload to lower
g-forces than Dragon and allow for a very short interval between leaving the
station and cargo offloading and processing on the ground. Such capabilites
will be extremely useful for returning delicate and time-sensitive
experiments.

So, until Dream Chaser becomes operational, almost all cargo return capability
will be provided by Dragon; and right now, the cargo that is returned not on
Dragon is on the order of a rounding error.

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ufmace
Thanks, that's interesting! Do you know if the future upgrades to Dragon with
propulsive landing for the crew return will provide similar capabilities for
fast landing at bases as the Dream Chaser?

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wolf550e
First flights of Dragon 2 will splash down under parachute because NASA is
nervous about propulsive landing. When propulsive landing happens (probably at
CCAFS) we'll see how fast can the capsule be decontaminated (superdraco uses
hydrazine fuel, will need something like this:
[https://www.wired.com/images_blogs/dangerroom/2011/11/120310...](https://www.wired.com/images_blogs/dangerroom/2011/11/120310af_x37_landing_800.jpg)).

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imglorp
I'm curious how Dragon carried a docking adapter to ISS. Such things generally
don't fit through hatches.

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mikeash
Dragon has an unpressurized "trunk" which it can use to carry stuff like this.
Here's a picture (a rendering, looks like, but it gets the point across) of
the adapter being removed from Dragon's trunk:

[http://imgur.com/LAMS49w](http://imgur.com/LAMS49w)

The rear part (with the solar panels) is discarded before the capsule at the
top returns to Earth.

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hedgehog
Here are some photos of the trunk on the ground:
[http://www.spacex.com/news/2013/03/26/dragon-
trunk](http://www.spacex.com/news/2013/03/26/dragon-trunk)

Quite a lot of space in there.

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ygra
The BEAM was transported in the trunk as well. That couldn't have fit through
any hatch either.

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gtirloni
> returning a load of NASA research from the International Space Station

Is it common practice to send down only, say, half of the results, while
keeping the other half at the ISS for backup purposes?

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wolf550e
ISS freezer is space limited. They might spread samples over different dragons
for safety, if they have the space.

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perseusprime11
SpaceX is really setting itself up for interstellar travel. I am really proud
of Elon Musk and SpaceX in general.

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lazaroclapp
Well, saying that SpaceX is setting up for interstellar travel is like saying
that me going kayaking is preparing me for transatlantic navigation... but
mighty impressive nonetheless.

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aurelianito
The first ocean navigators did use small rafts to do it. That's how they
managed to go to Easter Island, for instance. So your affirmation confirms
that SpaceX is preparing for interstellar travel.

