An EVA carries the risk that objects and people may become detached from the ship/structure and drift away from it. In the case of objects they might become a hazard or their loss might be a problem, but in the case of people it could be fatal.
I'm aware of NASA's EMU. For the purposes of this question it would have to be broken or out of propellant. Emergency devices that are not used in the normal course of an EVA are relevant though.
Has any space agency made plans for dealing with such an event?
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1$\\begingroup$ There's always the space harpoon... $\\endgroup$ – JCRM 7 hours ago
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1$\\begingroup$ Re For the purposes of this question it would have to be broken or out of propellant. That's at least four failures deep. An astronaut becoming detached during an EVA in and of itself is at least two failures deep. And now you have an additional two failures on top of that. NASA doesn't and can not plan for that many bad things happening in a row. $\\endgroup$ – David Hammen 6 hours ago
1 Answer
A nitrogen cold jet thruster system called SAFER (Simplified Aid For EVA Rescue) is part of the US EVA suit ensemble. If a crewperson gets loose they can fly back using SAFER.
(Image source)
SAFER is not used in the normal course of an EVA. There is no other propulsive system on a US EVA suit.
SAFER was deemed necessary for the ISS era because either the Shuttle would not be present at the ISS during the EVA, or even if present, would take considerable time to undock and prepare to chase down the free-floating crewperson.
This photograph shows SAFER being tested for the first time on shuttle mission STS-64.
(Image source)
The system is flown by the use of a single hand controller instead of the usual one translational / one rotational hand controller scheme. The user selects between rotational and translational modes via a switch on the hand controller module. However, the controller has four degrees of freedom in either mode, with pitch commands being available in translational mode, and X translation being available in rotational mode. An attitude hold mode is available to automatically stop undesired rotations.
(Image source)
Procedures for the use of SAFER are found in the ISS EVA Checklist.
Acronymology
- EV ExtraVehicular
- GCA Ground Controlled Approach
- HCM Hand Controller Module
- IV IntraVehicular
- WVS Wireless Vision System
Additional detailed information about the SAFER system is available here.
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$\\begingroup$ If no gas flow / BRN TRSRS $\\endgroup$ – Richard 33 mins ago
