> 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.
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.
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?
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...).
SpaceX Dragon is the only vehicle currently flying that has significant downmass capability. European ATV, Japanese HTV, Russian Progress and Orbitak ATK's Cygnus all have destructive reentry, meaning after they are unloaded at the station, they are filled with junk and disintegrate, burn up and sink in the Pacific.
You can take stuff back from the station in the Soyuz when it lands with returning crew, but space and mass are very limited. For example, Soyuz can't bring back the -80°C freezer with blood, saliva and urine samples from the astronauts (those are used, among other things, to calibrate exercise and diet regimens that lead to the least calcium loss from their bones in microgravity).
The Soyuz is not a 'cargo carrier', it is a 'people carrier'. It does have a service module that can carry a very small amount of cargo on the way up, but that gets ditched and burn up on the way down. The return capsule just carries the astronauts and personal effects (and it's a tight fit at that).
If it's anything like the first Apollo missions' capsules, it's pretty much three chairs tied back to back. There's barely enough room to sit in, I don't know how the astronauts didn't go crazy in it.
Yes - but no. It is similar - both have some aerodynamic shapes and carry three people - but that's about where similarities end. Soyuz return capsule is 2/3 of Apollo's by volume - which is restrictive. Shape is optimized for mass, so accelerations are less gentle.
Soyuz has another advantages over Apollo - like another module, separate from return capsule; together, those two modules provide livable volume 1.5 of Apollo's.
But for what we're talking Soyuz is more restrictive than Apollo.
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.