ORUs Return - Discussion of Potential

[411rocket]

Starting a new thread, as ideas proposed, could be ineresting.

Have a wild idea. If the ISS cooling issues requires a contingency flight to bring up EMUs, parts, etc. Can SpaceX refurbished a used Dragon and use the Thiacom 6 LV & the CRS-3 Dragon trunk for such a flight?

What is wrong with the existing CRS-3 Dragon?

Nothing, aside from the electrical mods (waterproofing & freezer requirements) + resultant testing, may need to be hastened. But then NASA, may have already asked them, after this problem occured. As this Dragon is slated to have a EMU fixture in it anyways.  I do not think, there will be another pump unit, ready for launch in the trunk section in time though. As it sounds like, it is the same type of unit changeout, as earlier this year. So they may need more spares soon.

It would be a real PITA, to get any failed pump units goundside. Depess Dragon, open side or main hatch (demating req for main) put pump unit into Dragon. This would preferably in a sealed bag, could a crew transfer bag be large enough? Close & secure hatch, re-mate if needed & repress Dragon. There will be more to it, of course, but this is the only way I can think of, without hauling it through the station itself. Might be better, to send up another Dragon later, for failed ORUs, if it comes down to it.

What would be the advantage of going to all that trouble as opposed to just bringing the unit into the ISS through the usual airlock and then to Dragon through the ISS?  That is, if it's even worth that much trouble to bring the failed unit back down to Earth.

Could the used PM have too much ammonia to justify bringing inside? That might preclude its ever returning to Earth.

Edit: sorry, we should probably continue this in another thread.

I should not be too a big of a deal, to get more pump units up to station, should fit in the trunk section (extended trunk if required). This was the 2nd pump unit, to fail this year, last was during expedition 35, with a leak. If NASA wants to examine any failed units, they probably will want to get 1 or more down intact. That means using the Dragon, for the return trip.

I had initially thought of, using a crew emergency tranfer bag, to seal any ammonia inside. But is it big enough, probably not, so custom sized ones would be needed, for sealing in any potential leakage. I agree with using a previously flown Dragon, for a Hazmat return flight, as the need to prevent contamination of other normal downmass. It would be too risky to take a pump unit inside the station, if it would even fit in the airlock. As recently, I was reminded of the bakeoff precautions, from just a few flakes of ammonia on the space suites.

So lets see, what other ideas are out there.

[watermod]

Could a NASA hyper-sonic inflatable heat-shield be of use for this return problem?
In other words skip the space ship and put it on the inflatable heat-shield - with some sort of support structure and de-orbit system brought up.  Say encapsulate it in a baggie ball inflated/filled with a Styrofoam so it can take a rough landing and have a parachute.
Bring the equipment up on any kind of supply flight.
The heat-shield was discussed in this thread: http://forum.nasaspaceflight.com/index.php?topic=29463.0

[Lar]

How much is it worth to return one of these units for closer examination? Because if you are talking about sending up a used Dragon on a special flight, you are talking serious cash. (even if you used a reused first stage too) You probably could build several new units and put one in the trunk of each subsequent CRS flight for a lot less than bringing one back on a special flight would cost.

But it would be awesome to do.

[docmordrid]

We lost a huge amount of capability when Shuttle was prematurely killed. That was the gamble with the $100 billion ISS, leaving it to the mercy of stockholders (foreign millionaires) more concerned about profit margins at commercial companies.

That seems a bit....well, whatever. Certainly seems a rap on Musk's nationality.

For the record, he is now a US citizen. While born in South Africa his maternal grandfather & great-grandfather were from the US.

And what of the US born well-off stockholders of Boeing, NG, LM etc.? Are they unconcerned with profits?

[DMeader]

I love posts that begin with "It should not be a big deal to...." Generally indicates a lack of understanding of the situation and the details involved.

[411rocket]

I love posts that begin with "It should not be a big deal to...." Generally indicates a lack of understanding of the situation and the details involved.

Maybe, but from my observations, of previous launches. Unpressurized cargo, has already gone to the ISS, in a Dragon's trunk. Also Elon had previously stated, building a longer trunk if needed, for sending up unpressurized cargo. Think it was during, one of the COTS Demo Press Conf, where he made the statement.

[SpunkyEnigma]

How do you get unpressurized cargo back?  The trunk is jettisoned before re-entry.

[411rocket]

How much is it worth to return one of these units for closer examination? Because if you are talking about sending up a used Dragon on a special flight, you are talking serious cash. (even if you used a reused first stage too) You probably could build several new units and put one in the trunk of each subsequent CRS flight for a lot less than bringing one back on a special flight would cost.

But it would be awesome to do.

That is up to NASA to decide, how badly they want to do study one or more & if they can shoehorn 2 in a Dragon.  But I am thinking of this as, a concept to consider, with no shuttles anymore & everything else, burns up on re-entry. I am also assuming that there is a small valve, between the mating adapter & the hatch to equilze pressure, normally used for sea level Vs station. In this case it, would need to be set to a "slow leak", for unpressurized hatch opening. Probably will need to be, repressurized & valve closed, prior to departure.

Yes, it would be an awesome thing, to pull off.

[douglas100]

I think that if ORU recovery is worth doing, then the best operational way of doing it would be to emulate Shuttle ops. The ORU should be recovered without ever bringing it inside the Station. This would entail modifying the Dragon systems so that the capsule can operate unpressurized. The side hatch would have to be enlarged to allow the ORU to be loaded or unloaded by hand or with the SSRMS.

I don't think either of these modifications will be simple or cheap. (The hatch enlargement may not be physically possible.) It would be equivalent to producing a specialized recovery vehicle. There would have to be a very good reason for recovery.

[Jcc]

I think that if ORU recovery is worth doing, then the best operational way of doing it would be to emulate Shuttle ops. The ORU should be recovered without ever bringing it inside the Station. This would entail modifying the Dragon systems so that the capsule can operate unpressurized. The side hatch would have to be enlarged to allow the ORU to be loaded or unloaded by hand or with the SSRMS.

I don't think either of these modifications will be simple or cheap. (The hatch enlargement may not be physically possible.) It would be equivalent to producing a specialized recovery vehicle. There would have to be a very good reason for recovery.

Good point. Also, you need to consider how the unit will be secured within the Dragon, and weight balance issues. I am pretty sure all the return cargo is arranged carefully and restrained so it can't move around.

[ehan_light]

Why would one need to enlarge the side hatch?
Why not simply hold the Dragon capsule with the Canadarm2 in about 1.5 meter distance from the station. One can open the hatch at the top and together with the second person they can maneuver the ORU through the hatch and secure [it] inside with as example straps?

[guckyfan]

In the context of Red Dragon it was mentioned that a larger hatch would be possible. But probably not when full earth pressure is maintained inside. Lower pressure would not be a problem for both applications. How the hatch would stand up to aerodynamic loads during reentry is another thing to evaluate.

How could that Dragon be operated? I would guess it would have to be berthed to the Station to be fixed in place. The robot arm can not do that because it is needed to move the equipment. The hatch to the station could not be opened due to the lower pressure. Too bad as it could not be used to carry pressurized cargo but it would hold some custom designed structure to house the downmass anyway.

Yes the modifications would not come cheap. But how much was Dragon development? The modifications would be a fraction of that as the basic structure would remain unchanged.

Probably not worth it for just the pump but a good capability to have if NASA decides to contract it.

[Jim]

Why would one need to enlarge the side hatch?
Why not simply hold the Dragon capsule with the Canadarm2 in about 1.5 meter distance from the station. One can open the hatch at the top and together with the second person they can maneuver the ORU through the hatch and secure [it] inside with as example straps?

Because an EVA person is going to have trouble opening the hatch, there will be no handholds

But worse, they won't be able to fit in the dragon with the package to install it.

Also, can the Dragon avionics work in a vacuum?

[Norm38]

This is the kind of application that full reuse allows, and that depends on reuse for low cost. When it becomes just the cost of fuel, then an empty dragon can be sent to ISS just to return cargo.

It may even be farther into the future. If that 8 meter methane MCT becomes reality and is reusable, it may be possible to design a second stage integrated mini-shuttle with a cargo bay, designed for this sort of work.

This is why reusability has to work, so much of what we dream depends on it.

[rst]

Why would one need to enlarge the side hatch?
Why not simply hold the Dragon capsule with the Canadarm2 in about 1.5 meter distance from the station. One can open the hatch at the top and together with the second person they can maneuver the ORU through the hatch and secure [it] inside with as example straps?

Because an EVA person is going to have trouble opening the hatch, there will be no handholds

But worse, they won't be able to fit in the dragon with the package to install it.

Also, can the Dragon avionics work in a vacuum?

If the Dragon is going to be grappled by the Canadarm the entire time, the Dragon doesn't need its RCS or sensors, so you could think about doing the operation with the avionics powered down --- which trades the cooling problem for a few others (like reinitializing everything on power up, and making sure that there isn't anything there which could conceivably get screwed up by just getting exposed to a vacuum).

Then again, as you point out, this stunt would probably require some design work just to add tie-downs for the ORU, and make sure that a suited astronaut could get to them.  If the ORU is rattling around on re-entry, it'll probably be in pieces on splashdown.  And the same may go for the spacecraft.

[Jim]

If the Dragon is going to be grappled by the Canadarm the entire time, the Dragon doesn't need its RCS or sensors, so you could think about doing the operation with the avionics powered down --- which trades the cooling problem for a few others (like reinitializing everything on power up, and making sure that there isn't anything there which could conceivably get screwed up by just getting exposed to a vacuum).

What is going to happen after it is power up, there still is no air?

There needs to be lighting for the crew to work inside it.

[rst]

If the Dragon is going to be grappled by the Canadarm the entire time, the Dragon doesn't need its RCS or sensors, so you could think about doing the operation with the avionics powered down --- which trades the cooling problem for a few others (like reinitializing everything on power up, and making sure that there isn't anything there which could conceivably get screwed up by just getting exposed to a vacuum).

What is going to happen after it is power up, there still is no air?

Not unless you have a way to repressurize the capsule, which is more extra gear (presumably with its own, vacuum-safe control systems).  But we're already in agreement that a current stock Dragon isn't set up for this sort of mission; it's more a matter of totaling up the bill.

There needs to be lighting for the crew to work inside it.

Another good point.

[mlindner]

I love posts that begin with "It should not be a big deal to...." Generally indicates a lack of understanding of the situation and the details involved.

Where's the +1 button. The ONLY conceivable way of bringing it down, without drifting into the advanced concepts forum, is possibly inside the spacecraft, even then, does it fit through all the various doors and passageways needed to get it to Dragon? Even if it does fit, there is the issue of ammonia contamination requiring a large custom bag for it, assuming it has no sharp corners that would cut through the bag. A spacecraft just to carry it down to avoid contamination with other things in the spacecraft isn't an option because of the cost. Not happenin'...

[mlindner]

Also, can the Dragon avionics work in a vacuum?

I've not heard of any modern COTS electronics, besides pressure sensors/gas analysis sensors, that break when exposed to vacuum, presuming they don't have any sealed boxes in the electronics bay that have no air vents. Would also need to make sure they don't depend on convection for electronics cooling.

Not arguing about any of the described situations being possible, just about the above point.

[DMeader]

Would also need to make sure they don't depend on convection for electronics cooling.

No convection in zero g. Along those lines, forced air, fans maybe, but that would just dump the heat into the cabin. I don't know Dragons thermal design... cooling loops, cold plates, pumps, valves, radiators. O God here we go again!

[manboy]

Why would one need to enlarge the side hatch?
Why not simply hold the Dragon capsule with the Canadarm2 in about 1.5 meter distance from the station. One can open the hatch at the top and together with the second person they can maneuver the ORU through the hatch and secure [it] inside with as example straps?

Also, can the Dragon avionics work in a vacuum?

I don't believe so.

[mlindner]

Would also need to make sure they don't depend on convection for electronics cooling.

No convection in zero g. Along those lines, forced air, fans maybe, but that would just dump the heat into the cabin. I don't know Dragons thermal design... cooling loops, cold plates, pumps, valves, radiators. O God here we go again!

That was what I was saying...

[Jim]

Would also need to make sure they don't depend on convection for electronics cooling.

That is my point.

[darkenfast]

While I don't believe that it's worth the trouble and risk to bring back one of these units, it does bring up the interesting point: during the design of the Dragon, did they make it possible for the spacecraft to be depressurized, either for an unforeseen circumstance such as this, or with an eye to later manned operations that might include an EVA in the manner of the Apollo Command Module? It does seem to be something that has to be allowed for in the initial design process. My uneducated guess is that they didn't, but it would be interesting to find out.

[CuddlyRocket]

Although bringing back the unit in one piece is ideal; short of ideal is often worth doing - so can they dismantle the unit and bring back some of the salient parts in a Dragon?

[Prober]

Although bringing back the unit in one piece is ideal; short of ideal is often worth doing - so can they dismantle the unit and bring back some of the salient parts in a Dragon?

getting back parts that fail is good science for long term spaceflight.    Seen NASA funds wasted on other projects.   This would be on my list as a sound expense. 
 

[MP99]

Edit: apologies for mis-quote - was intended to be a response to this message:-

Although bringing back the unit in one piece is ideal; short of ideal is often worth doing - so can they dismantle the unit and bring back some of the salient parts in a Dragon?

getting back parts that fail is good science for long term spaceflight.    Seen NASA funds wasted on other projects.   This would be on my list as a sound expense. 

I'd say that would be engineering rather than science, but I take your the point.

However, given the hassle just dealing with the QD's through spacesuit gloves, I just don't see how they could dismantle an ORU that was never designed for it.



Might be possible for future designs of ORU, but that would seem to massively increase the complexity of the design, probably leading to a higher failure rate in the first place.

cheers, Martin

[Xspace_engineerX]

It's actually been stated somewhere that they can attach an external Flow Control Valve to salvage this ORU. No need for return

[douglas100]

Why would one need to enlarge the side hatch?
Why not simply hold the Dragon capsule with the Canadarm2 in about 1.5 meter distance from the station. One can open the hatch at the top and together with the second person they can maneuver the ORU through the hatch and secure [it] inside with as example straps?

Ah the S word! (My bold.) If the Dragon is held on the arm then it is not available  to move either a person or the ORU. That makes things less simple. Better to have the Dragon docked or berthed to the Station.

I agree about the vacuum electronics problem discussed earlier. It was one of the things I had in mind when I said the modifications would neither be simple nor cheap. (This difficulty goes right back to Voskhod 2.)  A motorized enlarge side hatch, emulating the action of the Shuttles payload bay doors would probably be needed as well. Having sufficient volume to return the ORU in question is a given, of course. So is the point about centre of gravity placement made earlier.

I proposed this scenario to see what the general opinion was about how important ORU recovery is. I get the impression that a number of members think it's not worth doing. I tend to agree with that opinion.

[guckyfan]

I proposed this scenario to see what the general opinion was about how important ORU recovery is. I get the impression that a number of members think it's not worth doing. I tend to agree with that opinion.

I agree, it won't come cheap and fast, if and when needed. But it would not cost that huge an amount also. Probably it is not that urgent to get an ORU back. But they may want to place experiments outside and retrieve them without going through the station.

For that scenario NASA would have to contract that capability. And the retrieval flight would not need to be expensive beside the one time develoment cost. If the flight can be used for pressurized station resupply, the down capacity comes virtually free. Once the present backlog of downmass freezers and equipment from inside the station is cleared they may be able to dedicate flights for external downmass without needing to send a separate flight for the purpose.

[Norm38]

I've not heard of any modern COTS electronics, besides pressure sensors/gas analysis sensors, that break when exposed to vacuum

Lots of modern electronics still have electrolytic capacitors, and those will vent and fail in vacuum.  As ceramics can't match them for volumetric density, may still be in use on space hardware.
Point is, there are details to check, don't assume anything.

[MP99]

I've not heard of any modern COTS electronics, besides pressure sensors/gas analysis sensors, that break when exposed to vacuum

Lots of modern electronics still have electrolytic capacitors, and those will vent and fail in vacuum.  As ceramics can't match them for volumetric density, may still be in use on space hardware.
Point is, there are details to check, don't assume anything.

It looks to me like this may just be a matter of the casing being optimised for atmospheric pressure.

Is it possible to get them with tougher casings which are strong enough to withstand a vacuum? If so, it would seem to be a sensible precaution to use these in spacecraft electronics, even if intended for use in a pressurised section.

cheers, Martin

[Jim_LAX]

Tantalum capacitors have replaced the older borax and water electrolytic capacitors for any military applications.  They have even better capacitance to volume ratio and are available in metal cans with glass seals for very long life. No doubt they are available in vacuum rated versions too.
Even the pressurized section of a capsule may need to be vacuum rated in case an EVA becomes necessary.

[rst]

I've not heard of any modern COTS electronics, besides pressure sensors/gas analysis sensors, that break when exposed to vacuum

Lots of modern electronics still have electrolytic capacitors, and those will vent and fail in vacuum.  As ceramics can't match them for volumetric density, may still be in use on space hardware.
Point is, there are details to check, don't assume anything.

It looks to me like this may just be a matter of the casing being optimised for atmospheric pressure.

Is it possible to get them with tougher casings which are strong enough to withstand a vacuum? If so, it would seem to be a sensible precaution to use these in spacecraft electronics, even if intended for use in a pressurised section.

But then the circuit boards that include these capacitors are no longer COTS ("commercial, off the shelf").  And if, as some of us have been assuming, use of COTS components is part of SpaceX's cost-reduction strategy, your avionics costs just went up, possibly by a fairly large amount.  Even vacuum-qualifying COTS components that you expect to work could be a distraction.

It's worth remembering that this discussion started with the idea of using a "previously flown" Dragon, with the idea that it would be a cheap mission.  In that context, particularly given the strapped state of NASA's budget (with data analysis for Cassini and Curiosity on the chopping block), it's not likely they'd consider something like this unless it saved them money that they'd have to spend otherwise.  And in that context, every extra dollar spent tells.  So, unless the Dragon systems have been vacuum-rated already (which we wouldn't necessarily know), this is still worth talking about.

[Joffan]

Potentially the requirement for redesign could be reduced to a new hatch for external equipment return. The mission could otherwise be a normal cargo resupply/return, but with an adapted  hatch that allows for fitting and covering an ORU inside an additional shaped enclosure protruding into the body of the craft. The outer cover could either bleed slowly to ambient pressure (vacuum or atmospheric) or hold vacuum at some greater cost and risk.

The internal working volume, both up and return, would be reduced by the enclosure plus enough to allow the hatch to move with the internally-protruding enclosure.

Certainly not a cost-free option but perhaps fewer impacts on the internal status of Dragon working.

A reusable nosecap, in discussion on another thread, would allow a different protected external volume for this sort of proposed requirement.

[MP99]

I've not heard of any modern COTS electronics, besides pressure sensors/gas analysis sensors, that break when exposed to vacuum

Lots of modern electronics still have electrolytic capacitors, and those will vent and fail in vacuum.  As ceramics can't match them for volumetric density, may still be in use on space hardware.
Point is, there are details to check, don't assume anything.

It looks to me like this may just be a matter of the casing being optimised for atmospheric pressure.

Is it possible to get them with tougher casings which are strong enough to withstand a vacuum? If so, it would seem to be a sensible precaution to use these in spacecraft electronics, even if intended for use in a pressurised section.

But then the circuit boards that include these capacitors are no longer COTS ("commercial, off the shelf").  And if, as some of us have been assuming, use of COTS components is part of SpaceX's cost-reduction strategy, your avionics costs just went up, possibly by a fairly large amount.  Even vacuum-qualifying COTS components that you expect to work could be a distraction.

It's worth remembering that this discussion started with the idea of using a "previously flown" Dragon, with the idea that it would be a cheap mission.  In that context, particularly given the strapped state of NASA's budget (with data analysis for Cassini and Curiosity on the chopping block), it's not likely they'd consider something like this unless it saved them money that they'd have to spend otherwise.  And in that context, every extra dollar spent tells.  So, unless the Dragon systems have been vacuum-rated already (which we wouldn't necessarily know), this is still worth talking about.

ISTM that COTS does not mean lowest quality / price components, just not rad hardened.

As I speculated, and per Jim LAX's comment, it's possible that the avionics are already vacuum rated, to deal with contingencies.

Cheers, Martin

[Jim]

Even the pressurized section of a capsule may need to be vacuum rated in case an EVA becomes necessary.

Not if the capsule never intends to support EVA.