Currently there is a Dragon from SpaceX attached to the station. It is not equipped for but in a crisis it is capable of returning all crew members.
They've got a Soyuz for that.
As I have pointed out, in a crisis, where there are no other options, it is capable of returning humans. This would involve makeshift seats/beds and landing in the ocean.
If you are aware of a plan to use a Dragon as a lifeboat, please bring out some sources for that.
That's a pretty far fetched possibility and surviving re-entry in an unmanned capsule is unlikely. There aren't any life support capabilities (ie. oxygen for breathing) and surviving the 5-10 G accelerations of re-entry would be rather unlikely without being strapped to a seat.
Can the Dragon spacecraft even undock from the space station and robotic arm without a human operator on the Canadarm controls?
Your third paragraph is not correct at all. Dragon has life support and reentry acceleration of 3.5g.
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/2011001...
http://www.nasa.gov/pdf/361838main_11%20-%20SpaceX%20Augusti...
Quoting from the first pdf:
Environmental Control System
Astronauts will enter Dragon to remove cargo. Dragon’s cabin is habitable, with air circulation, lighting, fire detection and suppression, air temperature control, pressure and humidity monitoring.
Transporting Crew While it initially is transporting cargo, Dragon was designed from the beginning to transport crew and is currently undergoing modifications to make this possible. Crew configuration will include life support systems, a crew escape system, and onboard controls that allow the crew to take control from the flight computer when needed. This focus on commonality between cargo and crew configurations minimizes the design effort and simplifies the human-rating process, allowing systems critical to Dragon crew safety and ISS safety to be fully tested on unmanned flights.
And the second pdf:
Crew Capability
•Both Dragon & Falcon 9 were designed from inception to readily accommodate crew
•Immediate focus is on cargo for COTS & CRS commitments, BUT…
•In every design decision, the ability to attain human rating rapidly & at low additional cost is paramount Note: Many human-rating requirements are mandated on the cargo vehicle because it must be safe for ISS crew Space Exploration Technologies Corp June 16, 2009 This is why SpaceX was founded 21 Dragon Already Designed to Accommodate ISS Crew
•For COTS Capabilities A-C, astronauts will enter (and temporarily inhabit) the Dragon spacecraft for loading and unloading of cargo to and from the International Space Station
•Therefore, Dragon already meets the manned requirements to allow this activity, as called out in SSP 50808
•Air sampling and circulation
•ISS crew sample Dragon’s air supply through the Air Revitalization System (ARS) port before entering the spacecraft, breathing in the air as provided by the Dragon Environmental Control System.
• Air circulation is provided to ensure safe breathability throughout the spacecraft
•Temperature and humidity requirements
•Touch temperature limits: between 39 F and 113 F
•Human Factors
•Protection from shock
•Restrictions on sharp corners, sharp edges, exposed screw threads, burrs, and pinch points.
• All fonts, colors, and labels are consistent with SSP 50005.
Dragon is capable of docking and undocking, but for reasons, it is rather berthed via the Canadaarm.
But the question is: is there a planned procedure / contingency plan involving the Dragon as a lifeboat? If not, then it's not going to be used. They have rehearsed procedures for these situations. Including the worst of crises.
The 5 year old link you provided mentions the possibility of modifying the Dragon capsule to provide life boat capabilities. That's not what is up there today. The other one talks about "air circulation" systems, but that's not the same as life support.
Wouldn't it be safe to assume there is such a backup plan? You've got a vehicle that should be able to return humans to earth. If an emergency arose with other vehicle(s) damaged, why wouldn't the Dragon be in the mix? I would assume that in a worst case scenario, all sorts of unusual measures could be taken.
In contrast, the option of using the Lunar Module as a life boat in the Apollo 13 flight was planned and rehearsed ahead of time. Not all the details were worked out because it was thought that the crew would be dead before this would turn into reality (and the whole Apollo program was a bit rushed).
But yes, they must have thought long and hard about the option of using the Dragon. The whole Dragon program is built upon the idea of possibly using it as a life boat in the future but that is not the role of the Dragon up there at the moment. But the lessons learned have been translated into the next-gen human rated Dragon program.
But we don't really have to think about that. The last I heard, the CAPCOM and the crew were discussing about feeding the fruit flies onboard the ISS so the scientific objectives do not suffer more than they have to.
For detachment, nearly every large connection in space has explosive bolts for cutting things loose. The docking ports have emergency modes.
Please correct me if I'm wrong.
Berthing is what they do to ISS modules. It's basically bolted on--which requires a fair bit of work from the crew on the station side, both mechanically and in getting the spacecraft in place (which they do by robotic arm capture). They do this for the cargo stuff because the berthing mechanism is wider, lighter, and cheaper.
Docking is what you do for a manned spacecraft. They have fancy mechanisms to attach and detach quickly and mostly-automatically. It's complex and the opening is enough to get people through, but it's fast and easy. A docked spacecraft can leave on its own; a berthed one would require crew still on to help.
While cargo Dragon could take a person down to Earth, and they'd probably survive (probably nestled among bags of trash), it's not going to do so in a hurry, and since you have a seat on a Soyuz already, and it's designed for it, you might as well use that. Especially if you're in a hurry. I think the only time cargo Dragon would be involved would be something catastrophic happening to one of the Soyuz--but not to anything else.
In an extreme emergency, a crew could put on emergency breathing equipment, and use makeshift seating, then ride the capsule home.
One of the major reasons the Dragon v1 can't launch with human crew inside is that it has no launch abort system.