Author Topic: Interplanetary Injection Stage  (Read 2412 times)

Offline acastares

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Interplanetary Injection Stage
« on: 12/15/2014 10:52 PM »
Hi,

My first post. Fascinating boards and messages, have spent days (and nights) reading through them...!

I have read today 'The S-II Injection Stage for the Mars/Venus Flyby Mission' by WH Morita and JW Sandford at North American Rockwell, 196x.

They talk about using the S-II as an injection stage for Mars/Venus missions, and fuelling it in orbit, by two potential variants of the S-IVB or a purpose built tanker. They talk about the stage being in orbit for 10 days, and it receiving several tankers to fill up its LOX.

They do not mention LH2. My questions, if I may be so bold:

1. Could a S-II derived injection stage be in space for more than 10 days without any ill effect? I assume yes with some work.
2. Could a S-II derived injection stage receive LH2 as well as receiving LOX from tankers? I don't assume anything on this one - I have no clue.

I really appreciate any responses
Best
R.

Offline IslandPlaya

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Re: Interplanetary Injection Stage
« Reply #1 on: 12/15/2014 11:14 PM »
Welcome!
Great first post, and I have no idea about the answers you are looking for...
However someone will come along and give you more info than you could ever need!
:)

Offline kevin-rf

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Re: Interplanetary Injection Stage
« Reply #2 on: 12/16/2014 04:45 AM »
Now if the could just drop several tonnes of LOX and LH into LEO it would be a great help ;)
« Last Edit: 12/16/2014 04:45 AM by kevin-rf »
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Offline savuporo

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Re: Interplanetary Injection Stage
« Reply #3 on: 12/16/2014 04:54 AM »
1. Could a S-II derived injection stage be in space for more than 10 days without any ill effect? I assume yes with some work.
Highly unlikely. Rocket stages are not really designed as spacecraft, they have strictly limited task of boosting the payload to high velocity in a short amount of time.
On S-II specifically, you have to remember that it was designed to light itsengines at 40 miles up and burn full bore to 120 miles in short time, and thats it. If you tried to re-start this 10 days later, there would be a large number of problems. First your propellants, especially LH2 boils off rapidly. Hydraulic gimbals would freeze up. Batteries would die. Many things like fuel lines would get brittle and potentially rupture. Propellants dont feed nicely into pumps in near-zero g, you need a method to settle them. Igniter still needs to fire for all five engines .. etc.
Read through this and think about each subsystem, "what could possibly go wrong after long term exposure to space environment to each subsystem? After you have done that, multiply all the failure modes by about 10x ..

http://history.msfc.nasa.gov/saturn_apollo/documents/Second_Stage.pdf

Quote
2. Could a S-II derived injection stage receive LH2 as well as receiving LOX from tankers? I don't assume[ anything on this one - I have no clue.
In-space cryogenic liquid management is a technology that does not really exist today, much less in Apollo days. It would be especially tough with deep cryogenics with LH2, but nobody is even doing relatively more benign long duration LOX/hydrocarbon stages.

EDIT, Apart from subscale and component experiments on hydrazine US has really never pumped any rocket propellants around in space, so this is very much all completely unrealistic.
« Last Edit: 12/16/2014 07:12 AM by savuporo »
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Offline the_other_Doug

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Re: Interplanetary Injection Stage
« Reply #4 on: 12/16/2014 02:17 PM »
Thanks, savuporo, for finally stating some actual cold, hard facts when it comes to orbital fuel depot technologies.  Transferring hypergolic fuel between different stages in microgravity is not exactly a mature technology (witness some of the fuel leak issues the Russians ran across on Salyut 6 and, to a lesser extent, on Mir), and pumping cryogenic fuels in that environment is an almost undemonstrated technology.  Boil-off is indeed a serious issue, which is difficult to resolve in a more tractable environment such as Florida, much less in orbit or at a Lagrange point.

Until we've actually demonstrated an ability to store and transfer cryogenic fuels in microgravity, I think it is merely energetic arm-waving to insist that all we will ever need are F9-class boosters and that we can depend solely on undemonstrated depot technologies when designing reference missions for BLEO activities.  Until such technologies are demonstrated, I think it's more realistic to assume that you'll need to lift complete stages, fuel included, into orbit and use them in combination to accomplish BLEO maneuvers.

One telling point on how difficult depot technologies could end up being to develop is the fact that, during early Apollo planning, EOR lost out to LOR partially because EOR required demonstration of orbital cryogenic refueling by the 1965 timeframe, and this pacing factor appeared to be a deal-breaker to many who were eventually wooed over to the LOR mission architecture.  Launching two Saturns in the space of a day or so wasn't the issue -- refueling one from the other in orbit was.  While MSFC was certain they could overcome the engineering difficulties, remember they assumed all of the required propellant transfer would occur within hours of launch, and so avoided the need to maintain depots for indefinite periods.  So even their proposals for overcoming the more intractable problems of orbital cryogenic fuel transfers didn't demonstrate the kind of technologies you'd need to maintain cryogenic fuel depots.

There's nothing wrong with energetic arm-waving -- it can be a fun diversion.  But let's not imagine that anyone is going to spend a hundred billion dollars on trans-Mars habs and hundreds-of-tons Mars surface habs and landers and such and then find out, with everything on orbit and ready for refueling, that they can't get a full fuel load into their TMI stage.  There will have to be serious depot demonstrator missions well in advance before the money would be sunk into the rest of the hardware you need to go to Mars using depot architectures.
-Doug  (With my shield, not yet upon it)

Offline acastares

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Re: Interplanetary Injection Stage
« Reply #5 on: 12/16/2014 03:21 PM »
1. Could a S-II derived injection stage be in space for more than 10 days without any ill effect? I assume yes with some work.
Highly unlikely. Rocket stages are not really designed as spacecraft, they have strictly limited task of boosting the payload to high velocity in a short amount of time.
On S-II specifically, you have to remember that it was designed to light itsengines at 40 miles up and burn full bore to 120 miles in short time, and thats it. If you tried to re-start this 10 days later, there would be a large number of problems. First your propellants, especially LH2 boils off rapidly. Hydraulic gimbals would freeze up. Batteries would die. Many things like fuel lines would get brittle and potentially rupture. Propellants dont feed nicely into pumps in near-zero g, you need a method to settle them. Igniter still needs to fire for all five engines .. etc.
Read through this and think about each subsystem, "what could possibly go wrong after long term exposure to space environment to each subsystem? After you have done that, multiply all the failure modes by about 10x ..

http://history.msfc.nasa.gov/saturn_apollo/documents/Second_Stage.pdf

Quote
2. Could a S-II derived injection stage receive LH2 as well as receiving LOX from tankers? I don't assume[ anything on this one - I have no clue.
In-space cryogenic liquid management is a technology that does not really exist today, much less in Apollo days. It would be especially tough with deep cryogenics with LH2, but nobody is even doing relatively more benign long duration LOX/hydrocarbon stages.

EDIT, Apart from subscale and component experiments on hydrazine US has really never pumped any rocket propellants around in space, so this is very much all completely unrealistic.

Thanks for your thorough responses.

Regards 1, to be clear,  the paper talks about the S-II being launched as payload, rather than being part of the launch vehicle that is then refuelled in orbit. Also, they talk about modifications being made to the core S-II (the most obvious of which are the reduction to 2 engines only) to make it 'space proof' if you like.

Re 2, it is obvious that in whatever parallel timeline Saturn technology is used as an interplanetary injection stage would need a long term development programme and a long term testing phase.

Thanks
R

Offline acastares

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Re: Interplanetary Injection Stage
« Reply #6 on: 12/16/2014 03:23 PM »
Doug - Thanks, very informative response.

R

Offline savuporo

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Re: Interplanetary Injection Stage
« Reply #7 on: 12/16/2014 03:50 PM »
Regards 1, to be clear,  the paper talks about the S-II being launched as payload, rather than being part of the launch vehicle that is then refuelled in orbit. Also, they talk about modifications being made to the core S-II (the most obvious of which are the reduction to 2 engines only) to make it 'space proof' if you like.

Re 2, it is obvious that in whatever parallel timeline Saturn technology is used as an interplanetary injection stage would need a long term development programme and a long term testing phase.

With long enough time and engineering put into it, yes it would be possible, but not easy.

I think my point is that you would actually be pretty much just designing a new LH2/LOX deep space spacecraft, not using a S-II. Yes, you can use engines and even some tankage from an existing stage, but all the engineering requirements for a long duration spacecraft are substantially different from a rocket second stage. So you'd most likely be better off starting with clean sheet of requirements, pick the engines making sure that these can actually meet your requirements , and then design your spacecraft around it, only reusing components from elsewhere again if it meets your spec. Most likely you would have needed active cooling, requiring substantial power source, i.e. solar panels , radiators etc to make this work.
I don't think that J-2 would have even been able to meet the requirements unmodified - it's maximum rated interval between cut and restart was only 6 hours, but not sure if this was driven by stage or engine design.



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Offline Blackstar

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Re: Interplanetary Injection Stage
« Reply #8 on: 12/16/2014 04:13 PM »

I have read today 'The S-II Injection Stage for the Mars/Venus Flyby Mission' by WH Morita and JW Sandford at North American Rockwell, 196x.
 

Can you post that document?

Offline savuporo

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Re: Interplanetary Injection Stage
« Reply #9 on: 12/16/2014 04:29 PM »
Doc here

Quote
Adaptations of the S-II for injection will, therefore, require (1) removal of three engines, (2) provision of docking mechanism on the forward and aft skirts for the spacecraft and tankers, (3) incorporation of a propellant transfer system, (4) the use of high performance insulation, and (5) auxiliary solid rocket motors
for orbital operations.

I would call this a very optimistic. At the minimum, you'd need an extra power source.

Quote
Only two S-IIB subsystems not developed through previous programs superinsulation
and propellant transfer in earth orbit -are used in S-IIB stage design.
Technology required for these systems can be developed by the early 1970s.
And, this is actually not that unrealistic, because back in those days NASA and industry actually spent money on technology development.
« Last Edit: 12/16/2014 04:34 PM by savuporo »
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Offline R7

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Re: Interplanetary Injection Stage
« Reply #10 on: 12/16/2014 05:35 PM »

They do not mention LH2.

Because the plan was to launch the tankers first, then recycle the pads and launch the space craft and modified S-IIB filled with hydrogen only. S/C docks with S-IIB, tankers fill it up, inject.

Quote
My questions, if I may be so bold:
1. Could a S-II derived injection stage be in space for more than 10 days without any ill effect? I assume yes with some work.
2. Could a S-II derived injection stage receive LH2 as well as receiving LOX from tankers? I don't assume anything on this one - I have no clue.

Certainly, highlighting the keyword here.

The tankers were supposed to loiter 160+ days.
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Offline R7

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Re: Interplanetary Injection Stage
« Reply #11 on: 12/16/2014 05:42 PM »
I think my point is that you would actually be pretty much just designing a new LH2/LOX deep space spacecraft, not using a S-II.

Pointless point. The injection stage would have needed to last only up to 10 days at LEO. Minimum in the paper was 80 hrs. It goes into deep space only as a spent stage.
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Offline NovaSilisko

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Re: Interplanetary Injection Stage
« Reply #12 on: 12/16/2014 05:58 PM »
Reminds me of an idea I had for a bit of an alternate history scenario. An S-II derived reusable kick stage with some solar panels and a sunshade, lofted into orbit, with payloads attached to it. After that, it's refueled by tankers built using S-IVB tankage (launched perhaps atop a Saturn IB with no other payload, not sure how that would work out... need to check some numbers). The S-II gives the payload the majority of the delta-v it needs before performing a retroburn to keep itself in a highly elliptical earth orbit. Then, it aerobrakes back down to its normal orbit, and the process repeats.

Probably more trouble than it's worth though, the cost of all the S-IVB tankers could end up more expensive than just launching a new Aaturn V with a new escape stage.

Offline JasonAW3

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Re: Interplanetary Injection Stage
« Reply #13 on: 12/16/2014 07:17 PM »
I've pretty much been of the opinion that an interplanetary tug stage would be the best concept.  Fueled enough to make a flight to Mars with deceleration and orbit, OR sufficent to drop off a cargo that can self decelerate into orbit or for a landing, while the tug stage continues on back to Earth for refuel and refurbishment.

If stopped at Mars, it would have to be refueled from one of the martian moons (Hydrogen) and then launched back top Earth with whatever payload that is to be sent on the return trip.
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Offline savuporo

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Re: Interplanetary Injection Stage
« Reply #14 on: 12/16/2014 07:24 PM »
I think my point is that you would actually be pretty much just designing a new LH2/LOX deep space spacecraft, not using a S-II.
Pointless point. The injection stage would have needed to last only up to 10 days at LEO. Minimum in the paper was 80 hrs. It goes into deep space only as a spent stage.
10 days is about 20 times more than a LOX/LH2 upper stage has ever spent in space and still performed a burn.

The record for LOX/hydrocarbon stage is a one-time obscure and almost undocumented instance of 4 or 7 days according to different sources.

Upper stages are not spacecraft, they are designed to get a payloads to their intended orbits and die shortly thereafter.
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Offline R7

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Re: Interplanetary Injection Stage
« Reply #15 on: 12/16/2014 07:40 PM »
10 days is about 20 times more than a LOX/LH2 upper stage has ever spent in space and still performed a burn.

Not because longer loitering is technically insurmountable but because no need due to no funding for battlestars to Mars missions.

Quote
Upper stages are not spacecraft, they are designed to get a payloads to their intended orbits and die shortly thereafter.

Thank you for repeating my point.
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Offline Ronpur50

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Re: Interplanetary Injection Stage
« Reply #16 on: 12/17/2014 08:43 PM »
This discussion is exactly what I was looking for while reading Stephan Baxter's Voyage and building the model of the vehicle used.  His concept used a modified S-II stage and ETs made from S-II stages to power the TMI phase of the flight to Mars.  They were refueled before launch, but no details are given.  I wondered how feasible keeping LOX/LH2 in space would be.

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