Question Hatch opening from the outside

[IronRain]

Hi everyone,

This might be a weird question, but I'd always like to know how things work. So my question is, How can astronauts/cosmonauts open hatches (On the station, shuttle, soyuz..) from the outside? Do the need to install some special hardware for that or can this be done at any time?

Thanks,
Ironrain

 

[Urwumpe]

Hi everyone,

This might be a weird question, but I'd always like to know how things work. So my question is, How can astronauts/cosmonauts open hatches (On the station, shuttle, soyuz..) from the outside? Do the need to install some special hardware for that or can this be done at any time?

No special hardware needed, there is usually at least a socket for a wrench to do the pure mechanic part of that. The handling of the airlock though, requires to be controlled from within, there are only few controls inside the airlocks.

About the shuttle for example:

Three of the six latches on each hatch are double-acting and have cam surfaces that force the sealing surfaces apart when the latches are opened, thereby acting as crew assist devices. The latches are interconnected with push-pull rods and an idler bell crank that is installed between the rods for pivoting the rods. Self-aligning dual rotating bearings are used on the rods for attachment to the bellcranks and the latches. The gearbox and hatch open support struts are also connected to the latching system by the same rod/bellcrank and bearing system. To latch or unlatch the hatch, the gearbox handle must be rotated 440 degrees.

The hatch actuator/gearbox is used to provide the mechanical advantage to open and close the latches. The hatch actuator lock lever requires a force of 8 to 10 pounds through an angle of 180 deg rees to unlatch the actuator. A minimum rotation of 440 deg rees with a maximum force of 30 pounds applied to the actuator handle is required to operate the latches to their fully unlatched positions.

There are no interlocks that prevent you from opening both doors at once.

This photograph shows the handle for opening the airlock from the outside:

For opening a Soyuz capsule after landing from outside, the handles are stored in small compartments at the lower sides of the Soyuz, right next to the instructions for people around.

 

[T.Neo]

There are no interlocks that prevent you from opening both doors at once.

Ouch... :blink:

Aren't there safeguards for preventing the opening of a door when there's vacuum on the other side? I've heard the hatches on the CBM ports of the ISS have these, are they present on STS/Soyuz as well?

As a kid the entry hatch on the middeck scared me, and I wondered what would happen if someone opened it by "mistake"... :shifty:

 

[Urwumpe]

Aren't there safeguards for preventing the opening of a door when there's vacuum on the other side?

None aside of the pressure acting on the door. Which isn't enough to not be overcome by a human, with enough criminal energy. (Many horses could not be strong enough to force the door open, but a brain is enough).

Just as example: At each CBM acts a force about 500 kN by differential pressure between inside and vacuum, about equivalent to 42 tons of weight. I know no human who can even relief the seals a bit then, but he could still use the pressure equalization valve for venting the ISS.

It also makes no sense: if you for example use the airlock as ODS or for transfer to Spacelab, you want to open both doors at once.

 

[IronRain]

Thanks

 

[T.Neo]

Yes, but couldn't the interlock work by sensing a pressure difference? Or at least have a vacuum safeguard that works by acting on pressure difference?

 

[Urwumpe]

Yes, but couldn't the interlock work by sensing a pressure difference? Or at least have a vacuum safeguard that works by acting on pressure difference?

Why? In the worst case, a failed interlock would prevent you from leaving the space station in emergency. Or let astronauts return after EVA. It is simply not practical.

 

[garyw]

Yes, but couldn't the interlock work by sensing a pressure difference? Or at least have a vacuum safeguard that works by acting on pressure difference?

A good example of over-enginneering. If you can open the door, there is pressure on the other side. If you can't then you don't really want to. :lol:

The hatch I have most concerns about is the one on the shuttle which opens outwards and has a lot of pressure on it. Rumours were abound that a padlock was fitted to the unlatching mechahism for one mission....

 

[Grover]

yea, as we are now, you CAN depressurise the ISS, but astronauts arent that daft, they go through quite a bit of training to get there, i dont think they would accidentally kill the ISS crew by accident, especially when they cant do it without thinking and simply opening the door

 

[Urwumpe]

yea, as we are now, you CAN depressurise the ISS, but astronauts arent that daft, they go through quite a bit of training to get there, i dont think they would accidentally kill the ISS crew by accident, especially when they cant do it without thinking and simply opening the door

It would also take a lot of time. Using the pressure equalization valve for forcefully depressurizing the Shuttle would already take many hours.

 

[garyw]

It would also take a lot of time. Using the pressure equalization valve for forcefully depressurizing the Shuttle would already take many hours.

And set of alarms that detect lower pressures

 

[Ark]

So as long as the doors open inwards, the pressure of the atmosphere will be enough to prevent anyone from pulling the door open.

Sounds like a good way to mess with the newbies.

"I can't take it anymore!" *unlocks latches and pulls on CBM door*

"Nooooooo! You'll kill us all!" :lol:

 

[Turbinator]

So as long as the doors open inwards, the pressure of the atmosphere will be enough to prevent anyone from pulling the door open.

Sounds like a good way to mess with the newbies.

"I can't take it anymore!" *unlocks latches and pulls on CBM door*

"Nooooooo! You'll kill us all!" :lol:

Yeah, no thanks. I wouldn't try that for a million bucks.

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But I would do that if I was given a chance to go to space, under the condition that I try that.

 

[Orbinaut Pete]

Ouch... :blink:

Aren't there safeguards for preventing the opening of a door when there's vacuum on the other side? I've heard the hatches on the CBM ports of the ISS have these, are they present on STS/Soyuz as well?

As a kid the entry stage on the middeck scared me, and I wondered what would happen if someone opened it by "mistake"... :shifty:

The fact that negative pressure "sucks" the mid-deck hatch open, instead of closed like it does on ISS CBM hatches, is something that concerns NASA.

During the Payload Specialist, or "part-timer" program, a lot of the career astronauts, many of whom were seasoned military aviators, were worried that the untrained part-timers were going to freak out in space if a dangerous situation occurred. In his book "Riding Rockets", astronaut Mike Mullane described a Payload Specialist who took an unusual interest in the mid-deck hatch handle mechanism during training.

As such, a padlock arrangement was designed. To this day, when the Shuttle hits orbit, and escape is no longer necessary, the Commander goes down to the mid-deck and padlocks the hatch handle, so that it can't be operated. The Commander retains the key throughout the remainder of the mission.

It may have been a better idea than it's given credit for, as Payload Specialists did have mini freak-outs in orbit, most notably Taylor Wang's "I'm not coming back" episode on STS-51B. :blink:

 

[Turbinator]

Sneak a space ship to the ISS and surprise the astronauts, while they sleep.

 

[Urwumpe]

Sneak a space ship to the ISS and surprise the astronauts, while they sleep.

Docking alone should wake them up in an evil way.

 

[Carmen A]

Sneak a space ship to the ISS and surprise the astronauts, while they sleep.

There would be a problem sending your ninja ship into orbit undetected

 

[C3PO]

There would be a problem sending your ninja ship into orbit undetected

[ame="http://www.orbithangar.com/searchid.php?ID=3131"]

[/ame]

:rofl:

 

[OrbiterSpore]

hey wait; what about the thrusters and the chairs, c3?