Affordable habitats means more Buck Rogers for less money says Bigelow

[mfck]

Wouldn't it be possible to unload the fuel at the external dock into some storage system and decontaminate, then take it in?

[DMeader]

I'm interested that nobody's calling out hydrazine toxicity with the indoor Dragons. Is it sort of assumed that nontoxic dracos are on SpaceX's roadmap somewhere?

Did you read the thread? Like, the second post???

[A_M_Swallow]

Wouldn't it be possible to unload the fuel at the external dock into some storage system and decontaminate, then take it in?

Anything is possible, but is it worth while?

[mfck]

Wouldn't it be possible to unload the fuel at the external dock into some storage system and decontaminate, then take it in?

Anything is possible, but is it worth while?

Well supposedly it is, if you want the spacecraft in your habitat, isn't it?

[yg1968]

From the article:

Mr. Gold also noted that Bigelow is currently in negotiation with NASA for further activities and is cautiously optimistic that they will be able to make an announcement soon.

This is interesting if true. What near-term "further activities" might they be discussing?

My guess, probably the Asteroid Mission that the president seems so fixated upon.

During the November press conference, Gerst was asked if the Bigelow tugs could be useful for the asteroid capture mission, he said no, NASA is trying to push SEP and improved solar arrays technology for the asteroid capture mission, so they are not looking for a commercial tug. 

[DMeader]

I don't think we should take that drawing in any way seriously. There are many other issues with the concept. For instance, where are the Dragon trunks? No trunks...no solar panels...no power. Just about any spacecraft would have protruding booms/panels/antennas that would make fitting through the airlock problematical.

[A_M_Swallow]

Diring the November press conference, Gerst was asked if the Bigelow tugs could be useful for the asteroid capture mission, he said no, NASA is trying to push SEP and improved solar arrays for the asteroid capture mission, so they are not looking for a commercial tug. 

Hmm.  The tugs have a habitat.  So if NASA wants astronauts to stay at the captured asteroid for several weeks a tug could be used as living quarters and field laboratory.  However that would be a later mission.

[yg1968]

I don't think we should take that drawing in any way seriously. There are many other issues with the concept. For instance, where are the Dragon trunks? No trunks...no solar panels...no power. Just about any spacecraft would have protruding booms/panels/antennas that would make fitting through the airlock problematical.

The crewed Dragon will not have solar panels, it will run on batteries. We don't really know what crewed Dragon will look like except that it will look like "an Alien spaceship".

[yg1968]

Diring the November press conference, Gerst was asked if the Bigelow tugs could be useful for the asteroid capture mission, he said no, NASA is trying to push SEP and improved solar arrays for the asteroid capture mission, so they are not looking for a commercial tug. 

Hmm.  The tugs have a habitat.  So if NASA wants astronauts to stay at the captured asteroid for several weeks a tug could be used as living quarters and field laboratory.  However that would be a later mission.

I think that Gerst meant that the spacecraft capture tug wouldn't be used to capture the asteroid for that mission. 

[A_M_Swallow]

Diring the November press conference, Gerst was asked if the Bigelow tugs could be useful for the asteroid capture mission, he said no, NASA is trying to push SEP and improved solar arrays for the asteroid capture mission, so they are not looking for a commercial tug. 

Hmm.  The tugs have a habitat.  So if NASA wants astronauts to stay at the captured asteroid for several weeks a tug could be used as living quarters and field laboratory.  However that would be a later mission.

I think that Gerst meant that the spacecraft capture tug wouldn't be used to capture the asteroid for that mission. 

I agree with your interpretation of what Gerst meant.  A SEP will be used to bring the asteroid.  What sort of vehicle will be used to bring a long term habitat/space-station module is a different matter.

[Go4TLI]

Wouldn't it be possible to unload the fuel at the external dock into some storage system and decontaminate, then take it in?

When speaking about hypers, it's not just fuel (MMH typically) but also the oxidizer (N2O4).  Both are quite toxic when exposed to the right levels.

Is that possible, sure, but also problematic due to all the necessary equipment, storage tanks, time to load/unload, etc.  Also these are pressure fed systems.  Once of the easiest ways of "safing" the tanks are to isolate the high pressure system from the prop tanks.  One could then vent the respective prop tank ullage so there is no further driving force should a leak occur (outside of some much smaller pad pressure).  However even this would require a umbilical to the spacecraft and a way to properly vent the gas as it would also contain hyper vapors. 

[Go4TLI]

I don't think we should take that drawing in any way seriously. There are many other issues with the concept. For instance, where are the Dragon trunks? No trunks...no solar panels...no power. Just about any spacecraft would have protruding booms/panels/antennas that would make fitting through the airlock problematical.

Batteries.....and solar panels retract.  Dragon (and all vehicles that have a service module of some sort) have batteries in the CM/decent module/return vehicle or whatever one wants to call it. 

Plus we don't know the purpose of these hypothetical vehicles.  Are they for landing somewhere?  If so, then the truck really isn't necessary.  Are they for just short little drives around the block?  If so, there is a clock and a certain load defined for which the batteries can supply juice for that duration. 

[mfck]

Wouldn't it be possible to unload the fuel at the external dock into some storage system and decontaminate, then take it in?

When speaking about hypers, it's not just fuel (MMH typically) but also the oxidizer (N2O4).  Both are quite toxic when exposed to the right levels.

Is that possible, sure, but also problematic due to all the necessary equipment, storage tanks, time to load/unload, etc.  Also these are pressure fed systems.  Once of the easiest ways of "safing" the tanks are to isolate the high pressure system from the prop tanks.  One could then vent the respective prop tank ullage so there is no further driving force should a leak occur (outside of some much smaller pad pressure).  However even this would require a umbilical to the spacecraft and a way to properly vent the gas as it would also contain hyper vapors.

Supposing we are still in vacuum on the outer side of the habitat entry airlock, proper venting does not seem too problematic, or does it? As for the umbilical, I recon they'd have some sort of it anyway, like a robotic arm, for many other purposes as well as for actually getting the incoming craft into the airlock (I am assuming they won't rely solely on the propulsion to enter an airlock of a habitat containing functional humanoids. Maybe I am too cautious in my assumptions though)

[TrevorMonty]

IMHO having capsules in concept drawing was to show how large the Olympus is and what is possible with large airlock. The more likely use of this airlock is to bring in fully assembled modules to fit out a large space station. Think of it like a  empty shopping mall where complete shops are brought in via airlock.

[Go4TLI]

Supposing we are still in vacuum on the outer side of the habitat entry airlock, proper venting does not seem too problematic, or does it? As for the umbilical, I recon they'd have some sort of it anyway, like a robotic arm, for many other purposes as well as for actually getting the incoming craft into the airlock (I am assuming they won't rely solely on the propulsion to enter an airlock of a habitat containing functional humanoids. Maybe I am too cautious in my assumptions though)

It is actually.  Because now you are not just venting the ullage in a controlled manner to some lesser pressure. You are exposing the entire tank to vacuum and very well could damage any propellant acquisition device (such as screens) if they are in there. 

Remember there are no g-forces to settle the prop in any particular manner.  So just opening up to vac, beyond potentially damaging hardware, could easily suck not only the ullage but the prop out of the tank. 

Honestly, I am not familiar with the Dragon design to know if it uses screens, a bladder or some other method to pressurize the prop tank. 

But as you can see it would be a complicated process, one that seems unnecessary.  Just keep them externally docked.   

[mfck]

Supposing we are still in vacuum on the outer side of the habitat entry airlock, proper venting does not seem too problematic, or does it? As for the umbilical, I recon they'd have some sort of it anyway, like a robotic arm, for many other purposes as well as for actually getting the incoming craft into the airlock (I am assuming they won't rely solely on the propulsion to enter an airlock of a habitat containing functional humanoids. Maybe I am too cautious in my assumptions though)

It is actually.  Because now you are not just venting the ullage in a controlled manner to some lesser pressure. You are exposing the entire tank to vacuum and very well could damage any propellant acquisition device (such as screens) if they are in there. 

Remember there are no g-forces to settle the prop in any particular manner.  So just opening up to vac, beyond potentially damaging hardware, could easily suck not only the ullage but the prop out of the tank. 

Honestly, I am not familiar with the Dragon design to know if it uses screens, a bladder or some other method to pressurize the prop tank. 

But as you can see it would be a complicated process, one that seems unnecessary.  Just keep them externally docked.

Not for the sake of arguing, I really do not understand the problem.

1. Lower system pressure.
2. Separate the tankage from the rest of the system. (Valve?)
3. Introduce venting pressure from an umbilical
4....
5. PROFIT

Goes without saying the system has to be built with such process in mind. Apologies, if I am being thick, but your explanation just does not make sense for me.

[Go4TLI]

Propellant tanks are not just "empty tanks" with prop sitting inside them.  They have to have a method to get the prop to the engines that will use them.  In other words a constant flow of liquid prop (no gas, etc) to meet the mixture ratio the engine is designed to operate at.  These are commonly referred to as Propellant Acquisition Devices. 

So what I was saying earlier to vent a prop tank in the vacuum of space where there are no g-forces to settle the prop from the ullage is difficult.  Just "opening it up" could damage the prop acquisition device (whatever method is used). 

So the end result may very well be vented tanks.  However it could also mean damaged prop tanks as well as completely empty prop tanks. 

[dcporter]

Go4TLI, am I correct in assuming that your work next to a hypergol system would not have been possible if the system had recently fired and not been decontaminated?

[Jim]

Propellant tanks are not just "empty tanks" with prop sitting inside them.  They have to have a method to get the prop to the engines that will use them.  In other words a constant flow of liquid prop (no gas, etc) to meet the mixture ratio the engine is designed to operate at.  These are commonly referred to as Propellant Acquisition Devices. 

So what I was saying earlier to vent a prop tank in the vacuum of space where there are no g-forces to settle the prop from the ullage is difficult.  Just "opening it up" could damage the prop acquisition device (whatever method is used). 

most spacecraft use diaphrams

[Go4TLI]

Go4TLI, am I correct in assuming that your work next to a hypergol system would not have been possible if the system had recently fired and not been decontaminated?

No.  I was standing next to the orbiter within an hour or so of the engines (OME and thrusters) after they last fired.  I was certainly standing next to them within several hours to a day after we went into the OPF and did not have plugs installed, etc.  We did of course verify there were no gross leaks.

I'm not sure what you mean by "decontaminating".  There was none of that done ever to the system unless we were intentionally breaking into the system.