Author Topic: The space Tug  (Read 20532 times)

Offline Avron

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The space Tug
« on: 10/28/2005 04:22 am »
One item mentioned a few times is the concept of a space tug. I would guess that for the SDLV to be of use, a tug would be needed to "dock" componets launched via SDLV and other launch vehicles.

 Not only could it be used to dock components to the ISS but it could bring items to the ISS and provide station keeping, while the station arm grapples the componet. Assembly of larger space vehicle in orbit, could also do with a 'tug' or two.

I was wondering if there has been any official mention of such a tug and any plans on development?

Any ideas on what a space tug would look like? It capabilities?

Offline lmike

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RE: The space Tug
« Reply #1 on: 10/28/2005 04:32 am »
If you look at this recently released ESAS slide: http://images.spaceref.com/news/2005/nas.esas.16.l.jpg , there is a planned service module+unpressurized cargo palette version of the LEO CEV (3rd from the left).  I believe that is the tug (if you delete the container and just leave the palette with the payload interface fixtures*).  However, it goes on top of the CLV and has a declared payload of 6MT.  I would think it could be adapted to be launched on the HLV however, and/or to meet up with the pre-launched payloads to be hauled.

*and add an SRM arm to it to grapple the payloads

Offline kraisee

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RE: The space Tug
« Reply #2 on: 10/28/2005 05:43 am »
The SDLV 'Tug' is being folded into the design of the upper stage.

The upper stage itself will have a fully automated multiple-redundant RCS systems built in, which will allow it (and it's payload) quite a bit of manoeuverability.

And for lunar missions, remember that it has been designed to retain about 90-95 tons of propellant on board, after LEO injection, for use on the TLI burn to send everything moon-ward.   That's a LOT of fuel.
"The meek shall inherit the Earth -- the rest of us will go to the stars"
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Offline lmike

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RE: The space Tug
« Reply #3 on: 10/28/2005 06:04 am »
"The upper stage itself will have a fully automated multiple-redundant RCS systems built in..."  

Oh, this is a new development to me.  So it's going to be a 'smart' stage.  Thanks for sharing the info!  For some reason, I had the impression they'd launch the departure stage into a stable parking orbit, and then the lunar CEV's service module would be the one to do the approach, prox ops, and hook up to it for the moon flights.  Then, that's the heavy tug.

Offline AndyMc

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RE: The space Tug
« Reply #4 on: 10/28/2005 12:42 pm »
Quote
kraisee - 28/10/2005  12:43 AM

The SDLV 'Tug' is being folded into the design of the upper stage.

Hi,

Great news. Where did you get this info from? Is the first I heard of it, and makes perfect sense. Could it, or are there any plans to make it re-fuelable. It will need to be quite a sophisticated piece of kit if it is to remain in orbit any length of time. I guess the disposable stage used for TLI, would not have cryogenic cooling or the multi-redundant RCS, or will it?

Something like this was proposed for the OASIS project some years ago - the hybrid propellant module, though it had a seperate Chemical transfer module that contained the two engines. Perhaps some of these technologies will find their way into this upperstage design.

http://spacecraft.ssl.umd.edu/old_site/academics/484S03/oasis_docs/oasis_pics/
http://spacecraft.ssl.umd.edu/old_site/academics/484S03/

http://spacecraft.ssl.umd.edu/old_site/academics/484S03/oasis_docs/OASIS_FY01_FINAL.PDF
http://spacecraft.ssl.umd.edu/old_site/design_lib/OASISEXEC_97.pdf




Offline Avron

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RE: The space Tug
« Reply #5 on: 10/28/2005 02:42 pm »
Thanks.. good news...

Now I was hoping that the 'Tug' could be launched a little earlier and stay in orbit, so other options could be used to get  items launched.. maybe even use some commercial vendors to launch and 'dock' the tug with the component and move it to its station..

I guess that the SDLV upper stage could do the trick, so maybe it can be developed first and launched using a EELV/CLV (mass may be a problem) before the rest of the SDLV is developed to provide options before 2018.

Offline kraisee

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RE: The space Tug
« Reply #6 on: 10/29/2005 04:21 am »
Quote
AndyMc - 28/10/2005  8:42 AM

Quote
kraisee - 28/10/2005  12:43 AM

The SDLV 'Tug' is being folded into the design of the upper stage.

Hi,

Great news. Where did you get this info from? Is the first I heard of it, and makes perfect sense.

...


Yes, it does make sence.   You don't want the the tiny CEV's RCS system being the only thing available to reposition the entire 100+ tons of Earth Departure Stage & propellant, Lunar Surface Access Module, CEV CM and SM in preparations for the TLI to go to the moon.

The Upper stage will thus be able to perform automated rendezvous even if there is no CEV or crew involved - and this will be very useful for sending automated craft to the moon and building things in LEO too - like a Mars spacecraft.
"The meek shall inherit the Earth -- the rest of us will go to the stars"
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Offline realtime

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RE: The space Tug
« Reply #7 on: 10/29/2005 05:57 pm »
But this upper stage "tug" is designed to be expendable, yes?  If that's true then this is not a "tug", it is a disposable OMS, good for no more than the mission it launched on.

My definition of a tug is a spacecraft that is designed to stay on orbit and handle payloads from multiple launches.  It would contain a sophisticated OMS to allow it to dock with payloads and guide them to ISS or to rendezvous at assembly points.  It may (or may not) be refuelable on orbit.  To allow the tug to dock successfully, payloads would carry only a kick motor for circularization and a minimal RCS system to prevent tumbling.

Theoretically, this configuration would allow mission planners to throw "dumb" payloads into LEO and then maneuver the payload without the expense of certifying, boosting, and discarding a full-up OMS on every HLLV flight.


Offline AndyMc

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RE: The space Tug
« Reply #8 on: 10/29/2005 07:50 pm »
Hi,

It's well within the realms of possibility that there will be a tug version and an expendable version of the upper stage. There has  been plenty of research into cryo cooling done by NASA over the years. Where better to test it than in an unmanned vessel in LEO, before trying to rely on it for a 3 year round trip to Mars.


Offline Peter NASA

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RE: The space Tug
« Reply #9 on: 10/30/2005 03:20 am »
Quote
AndyMc - 29/10/2005  2:50 PM

Hi,

It's well within the realms of possibility that there will be a tug version and an expendable version of the upper stage. There has  been plenty of research into cryo cooling done by NASA over the years. Where better to test it than in an unmanned vessel in LEO, before trying to rely on it for a 3 year round trip to Mars.


That is correct and these tug boats are an intriguing addition to the overall future planning.

Offline Avron

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RE: The space Tug
« Reply #10 on: 10/31/2005 12:24 am »
Quote
realtime - 29/10/2005  1:57 PM

But this upper stage "tug" is designed to be expendable, yes?  If that's true then this is not a "tug", it is a disposable OMS, good for no more than the mission it launched on.

My definition of a tug is a spacecraft that is designed to stay on orbit and handle payloads from multiple launches.  It would contain a sophisticated OMS to allow it to dock with payloads and guide them to ISS or to rendezvous at assembly points.  It may (or may not) be refuelable on orbit.  To allow the tug to dock successfully, payloads would carry only a kick motor for circularization and a minimal RCS system to prevent tumbling.

Theoretically, this configuration would allow mission planners to throw "dumb" payloads into LEO and then maneuver the payload without the expense of certifying, boosting, and discarding a full-up OMS on every HLLV flight.

Thats what I had in mind for a Tug. Now what would prevent a SDLV upper stage from being launch into LEO an remain there for say a year, playing the roll of a Tug?

Offline FransonUK

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RE: The space Tug
« Reply #11 on: 10/31/2005 09:24 am »
Anyone have an image of what a space tug would look like?
Don't ya wish your spaceship was hot like me

Offline nacnud

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RE: The space Tug
« Reply #12 on: 10/31/2005 10:13 am »

This is Boeings first spacetug [astronautix], it seems like a very useful vehicle

The original BoeingSpace Tug design of the early 1970's was sized to be flown either in a singleshuttle mission or as a Saturn V payload. Optimum mass was found to be 20.6tonnes regardless. The Tug could be outftted with a variety of kits to serve inmany roles, including as a manned lunar lander. Aerobraking for recovery in lowearth orbit was considered for further study, but the baseline used RL10engines to brake into earth orbit for refurbishment and refuelling at a spacestation. All further work was cancelled by NASA in 1972, but resurrected as theaerobraking Orbital Transfer Vehicle in the 1980's.

http://www.astronautix.com/graphics/z/zstugmw.jpg" />
http://www.astronautix.com/graphics/z/ztugcrew.jpg" />


Offline nacnud

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RE: The space Tug
« Reply #13 on: 10/31/2005 11:01 am »
Crap, I just added information on some other space tugs such as the TKS, Parom, the Turtle 2 OTV, Orbital recoveries Cone express, etc but the post didn't work. Still heres a pic of the proposed Parom next to the klipper, you'll have to google for the rest :(
http://uplink.space.com/attachments//364545-futureK2.jpg" />

Offline Tap-Sa

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RE: The space Tug
« Reply #14 on: 10/31/2005 11:05 am »
Quote
This is Boeings first spacetug [astronautix]

Looks neat, but getting down to surface from the lunar version would be interesting.

"One small step for maAAAAAAAAANNN*THUMP*" ;)

Offline nacnud

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RE: The space Tug
« Reply #15 on: 10/31/2005 11:07 am »
:D

Offline FransonUK

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RE: The space Tug
« Reply #16 on: 10/31/2005 11:07 am »
Quote
Tap-Sa - 31/10/2005  6:05 AM

Quote
This is Boeings first spacetug [astronautix]

Looks neat, but getting down to surface from the lunar version would be interesting.

"One small step for maAAAAAAAAANNN*THUMP*" ;)

Looks like an alien grasshopper gone wrong :)

Thanks for the pics Nacnud :)
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Offline rsp1202

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RE: The space Tug
« Reply #17 on: 10/31/2005 06:35 pm »
Still not as bad as von Braun/Ley's "Conquest of the Moon" passenger ship c. 1953. The crew compartment on that one was in another time zone. Short and squat makes more sense.

As for space tugs in general, what capabilities will they have for crew rescue, or will that mission be left to CEV?

Offline lmike

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RE: The space Tug
« Reply #18 on: 11/01/2005 12:50 am »
Quote
Avron - 30/10/2005  7:24 PM
Quote
realtime - 29/10/2005  1:57 PM
...
Theoretically, this configuration would allow mission planners to throw "dumb" payloads into LEO and then maneuver the payload without the expense of certifying, boosting, and discarding a full-up OMS on every HLLV flight.

Thats what I had in mind for a Tug. Now what would prevent a SDLV upper stage from being launch into LEO an remain there for say a year, playing the roll of a Tug?

One would be long-term power generation, I would think.  One of the basic requirements for the CEV's SM is at least 6 months on-orbit lifespan as it'll do a double duty as the station's CRV (and could potentially be an orbital based light hauler for 6 tonne modules).  That's partially why they switched from Apollo's fuel-cells to solar panels.  An orbital tug version of the HLV's stage would need to grow some solar panels too I would think.

Offline realtime

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RE: The space Tug
« Reply #19 on: 11/01/2005 03:40 am »
Quote
Avron - 30/10/2005  8:24 PM

Quote
realtime - 29/10/2005  1:57 PM
...

Theoretically, this configuration would allow mission planners to throw "dumb" payloads into LEO and then maneuver the payload without the expense of certifying, boosting, and discarding a full-up OMS on every HLLV flight.

Thats what I had in mind for a Tug. Now what would prevent a SDLV upper stage from being launch into LEO an remain there for say a year, playing the roll of a Tug?
Propellant boil-off is a technical issue that has yet to be solved well.  Failing that, on-orbit refueling.


Offline Avron

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RE: The space Tug
« Reply #20 on: 11/02/2005 03:35 am »
Quote
realtime - 31/10/2005  11:40 PM

Quote
Avron - 30/10/2005  8:24 PM

Quote
realtime - 29/10/2005  1:57 PM
...

Theoretically, this configuration would allow mission planners to throw "dumb" payloads into LEO and then maneuver the payload without the expense of certifying, boosting, and discarding a full-up OMS on every HLLV flight.

Thats what I had in mind for a Tug. Now what would prevent a SDLV upper stage from being launch into LEO an remain there for say a year, playing the roll of a Tug?
Propellant boil-off is a technical issue that has yet to be solved well.  Failing that, on-orbit refueling.

I would guess that would be one limiting factor, and energy would be the other.. I wonder how long the current thinking in the  SDLV upper stage would last in LEO.. Not sure I would want to refuel... I would just launch another, it would cost less.. IMHO..

Offline realtime

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RE: The space Tug
« Reply #21 on: 11/02/2005 04:21 am »
Refueling may be nothing more than popping off the old tanks and connecting the new ones (also boosted on a dumb payload).  Or it may, like the example posted earlier, be a function that is performed at a service depot by humans.

Since it just seems intuitively more efficient to do automatic refueling on orbit, I'd like to see it done that way.  Such automation is also a very useful capability to have in our space bag o' tricks.  However, as you suggest, an engineering analysis may show it to be cheaper, especially in the short run, to discard it after it has handled a number of payloads.


Offline AndyMc

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RE: The space Tug
« Reply #22 on: 11/02/2005 09:15 am »
Have some more info (not much) on the Prom Space-tug.
http://www.friends-partners.org/pipermail/fpspace/2005-June/015892.html

It appears to me that to complement the tug there were plans for a logistics module (on the right). Perhaps this has been replaced now by an unmanned version of the klipper which would carry freight and fuel to and from the ISS. It could of course pick-up and de-orbit other types of supply modules/canisters. Theres also some talk about recovering these using a balute type chute.

Also from: http://www.libertypost.org/cgi-bin/readart.cgi?ArtNum=98220

A space tugboat
With the prospects of the Kliper growing brighter, and the expansion of the space station to accommodate a permanent six-person crew, Russian space engineers also realized that their classic space logistics system would be unable to deliver enough cargo.

For more than two years now, with the U.S. shuttle fleet grounded, the space station has been kept supplied by Russian robot space freighters of the "Progress" series. Each one can carry about two and a half tons of cargo, and three or four are launched every year. They follow the same launch-to-docking profile as the manned "Soyuz" vehicles and share most of their control systems.

Last month, Russian space official Nikolay Bryukhanov said that the Progress system would be replaced by a new space transportation system based on an entirely different concept. It will be called "Parom" (Russian for "ferry") and will replace the throwaway Progress model with a reusable space tugboat.

The Parom will be placed in orbit near the space station and then patiently wait for cargo canisters to be launched from Earth. These canisters will not need the complex and expensive control systems of a Progress vehicle; instead, a standard docking interface will allow the Parom to latch onto them as they draw near. The Parom will then use its guidance and propulsion systems to deliver the cargo to the space station.

“Any Russian or foreign launch vehicle can orbit such containers,” Bryukhanov said. “This can be an airtight instrument module or a fuel tanker,” he suggested, or even “an unpressurized platform featuring large scientific equipment and auxiliary systems [such as] solar batteries that cannot be stored inside an airtight module.”

In layout, the Parom will be built around a pressurized transfer passage with docking ports at each end: one to dock to the cargo module, the other to dock to the space station. It will have its own engines, along with propellant transfer lines to feed from the cargo canister into its own tanks or into the space station’s tanks. It will also have engines scaled to handle cargo modules weighing up to 60,000 pounds, twice the mass of the largest station sections carried into orbit aboard space shuttles.

The same space tugboat technique will not only allow expansion and resupply of space stations, he added, but also the assembly of multi-modular vehicles for manned and unmanned flights into deep space. The Parom could also toss payloads into higher Earth orbits, or push waste containers down into the atmosphere for incineration, and then reverse its own course and stay in orbit for its next mission. As needed, it could be serviced by spacewalking cosmonauts based at the space station.

Bryukhanov said he expected that the Parom, which would be rely on a heritage of proven Progress hardware, would be a commercial money-maker within a few years of deployment.

Key to Parts From the Link:

1.         can't find

2.         Parom spacecraft

3.         can't find

4.         dry cargo hold

5.         cargo propellant tanks

6.         Cargo canister interface hardware

7.         Docking cone on cargo canister

8.         Section for control electronics

9.         Section for control electronics

10.        Interface to International Space Station

11.        Section for propellant tanks

12.        Attitude control thrusters on cargo canister

13.        Can't find

14.        Cargo canister control systems

15.        Something else


Offline Avron

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RE: The space Tug
« Reply #23 on: 11/02/2005 03:07 pm »
Quote
AndyMc - 2/11/2005  5:15 AM

Have some more info (not much) on the Prom Space-tug.
http://www.friends-partners.org/pipermail/fpspace/2005-June/015892.html



I like, now I wonder what NASA could do.. Thanks for all in inputs..

Offline AndyMc

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RE: The space Tug
« Reply #24 on: 11/02/2005 05:59 pm »
Hi,

Taking the concept of the Parom being used to de-orbit logistic modules and Kliper, the CEV's Service module has more than enough reserve fuel to re-orbit itself and return to the ISS after sending a CEV towards Earth . It wouldnt be a versitile as the Parom, though if it was equipped with two engines (either side of centre) or 3 or 4 smaller ones, it could have a through tunnel with docking ports at either end. Perhaps this SM could be just another version of the one currently planned. It would be used afterwards to pick-up supplies launched to Orbit by the likes of SpaceX. Their final mission would be to act as TLI/TMI stages to launch probes etc into deeper space.

Here's an add-on I made for Orbiter that illustrates the idea.


Offline lmike

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RE: The space Tug
« Reply #25 on: 11/03/2005 05:53 am »
Neat.  But I think you need to add the solar panels to the SM-tug.

Offline stargazer777

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RE: The space Tug
« Reply #26 on: 03/06/2006 09:55 am »
Lots of interesting concepts.  But, for the short term, doesn't it strike you that there are likely to be lots of largely unused CEV service modules floating about once the CEV is put into service transiting to the ISS.  Could they be put to use rather than simply disposed of in the atmosphere?  Or, alternatively, would it be cheaper for NASA to simply launch a dedicated CEV modified to serve as a tug for the duration of its fuel supply (assuming we still haven't licked the refueling situation by that point.)?  This vehicle could be "parked" at the ISS and used for whatever "tug" duties might be required in orbit.  If and when the service module exhausts its fuel, we could launch a new one and attach it while disposing of the old one, if the tug had been designed with that capability in mind.  Make any sense?

Offline Jim

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RE: The space Tug
« Reply #27 on: 03/06/2006 11:40 am »
Quote
stargazer777 - 6/3/2006  4:55 AMLots of interesting concepts.  But, for the short term, doesn't it strike you that there are likely to be lots of largely unused CEV service modules floating about once the CEV is put into service transiting to the ISS.  Could they be put to use rather than simply disposed of in the atmosphere?  Or, alternatively, would it be cheaper for NASA to simply launch a dedicated CEV modified to serve as a tug for the duration of its fuel supply (assuming we still haven't licked the refueling situation by that point.)?  This vehicle could be "parked" at the ISS and used for whatever "tug" duties might be required in orbit.  If and when the service module exhausts its fuel, we could launch a new one and attach it while disposing of the old one, if the tug had been designed with that capability in mind.  Make any sense?

The CEM SM has only the tanks, engines, radiators, and solar arrays.  The CEV CM has all the avionics, batterys, heat rejection hardware, etc.  SM is actually "dumber" than a launch vehicle stage.  The SM is being made to be disposable and any mods and you would be changing the whole CEV architure.

Offline stargazer777

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RE: The space Tug
« Reply #28 on: 03/06/2006 12:27 pm »
Perhaps I didn't make myself clear.  My fault considering the hour I wrote my original message.  I was thinking about using a modified CEV with service module as a tug.  Depending on where the modifications were located, I was wondering if the CEV could stay in space and simply swap partially used service modules abandoned by other CEVs.  Maybe a foolish question, but its often easier to use existing hardware than develop something new.

Offline Jim

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RE: The space Tug
« Reply #29 on: 03/06/2006 12:46 pm »
Quote
stargazer777 - 6/3/2006  7:27 AMPerhaps I didn't make myself clear.  My fault considering the hour I wrote my original message.  I was thinking about using a modified CEV with service module as a tug.  Depending on where the modifications were located, I was wondering if the CEV could stay in space and simply swap partially used service modules abandoned by other CEVs.  Maybe a foolish question, but its often easier to use existing hardware than develop something new.

It was in another thread, that I said the unmanned version of the CEV is a tug.  Swapping SM's would be hard.  Refueling would be the way to go.

Offline stargazer777

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RE: The space Tug
« Reply #30 on: 03/06/2006 02:17 pm »
Thanks for the clarification!  That sounds like it will due for the time being.

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