Some ATL US Space Program questions, with pictures.

Ok, so I keep getting interested in the dang space ATL and discussions, and thought I would start tossing pictures/ideas out here, in no particular order.

For comparison in size between the Apollo and SS programs, I doctored this up so I would have some kind of an idea of how things measured up between the two programs.

SJBtRWPl.png


I don't propose that anything like what I am showing in this image be considered for a launch, just getting some visual aids input and can then go from there.
 
Ok, so I keep getting interested in the dang space ATL and discussions, and thought I would start tossing pictures/ideas out here, in no particular order.

For comparison in size between the Apollo and SS programs, I doctored this up so I would have some kind of an idea of how things measured up between the two programs.

SJBtRWPl.png


I don't propose that anything like what I am showing in this image be considered for a launch, just getting some visual aids input and can then go from there.
So, in the image on the left is the OTL shuttle, and on the right I have superimposed the whole Apollo package {CSM/LL}, atop the ET, both SRB, and replacing the SS nose section. Before I did this, I had no idea just how small the Apollo package was in comparison to the SS.

From this image, I get some questions:
1) Can a SS SRB lift a complete Apollo package? Assume no LL and instead a disposable (Or not) LRB or a much larger and more powerful SM. Cost wise, could such a launch put a return capsule into LEO at an affordable price?

2) Looking at the SLS, which to me looks like an improved Apollo CSM, with a booster, stuck atop the SS ET, it seems sure that a modified ET could be built to do that job. With no shuttle attached, could more than one CSM be lofted on a mission?

3) If the shuttle didn't need to return to Earth, could the space only version have an Apollo esque package built into the nose for the crew return? With no need for the TPS and all the weight savings that such a change would entail, what would the modified SS look like, and what could it lift into orbit? How long could an unmaned SS remain in useful condition, for the crews of future missions to use in building Space stations? What other missions could such a Orbital Shuttle do?

Other questions, if the space program can park a few of these OS upstairs, and get them to last for a year or two, what cost savings can we see without having to keep relaunching OTL SS on each mission?
 
Can a SS SRB lift a complete Apollo package? Assume no LL and instead a disposable (Or not) LRB or a much larger and more powerful SM. Cost wise, could such a launch put a return capsule into LEO at an affordable price?

According to my math, a single SRB can't even lift itself into orbit.

Looking at the SLS, which to me looks like an improved Apollo CSM, with a booster, stuck atop the SS ET, it seems sure that a modified ET could be built to do that job. With no shuttle attached, could more than one CSM be lofted on a mission?

If safety weren't an issue, a shuttle-C (that's a rocket based on space shuttle components) type system should be able to launch 3-4 CSMs at once. I wouldn't want to put crew on that launch though, since the hypergolic propellants in the SM would make things messy if things went wrong.

If the shuttle didn't need to return to Earth, could the space only version have an Apollo esque package built into the nose for the crew return?

That would require major changes to be made to the orbiter's nose. It would be a heck of alot cheaper to launch the Apollo command module in the orbiter's cargo bay. Mate it to a safer and smaller ('cuz it's not going to the moon) SM, and you have a nice return system for your crew.

I'm not sure about the answers to your other questions.

fasquardon
 
According to my math, a single SRB can't even lift itself into orbit.
Fair enough. I know that the SRB doesn't go so high that we have problems reusing them, but what kind of additional delta V is needed over and above that provided by the SRB? Or is the SRB flight profile just plain not suited for this task? 2 minute burn leaves the CSM 8 minutes shy of orbit? Or something like that?

If safety weren't an issue, a shuttle-C (that's a rocket based on space shuttle components) type system should be able to launch 3-4 CSMs at once. I wouldn't want to put crew on that launch though, since the hypergolic propellants in the SM would make things messy if things went wrong.
Could the SM be made to work with something like the SSME's? Or is the OTL the only way they could have worked? I don't know enough to ask a better question, so were the old Apollo SM not just using a less advanced/more toxic fuel? Or were there reasons other than this for the hypergolic (whatever that is) propellent use on the SM? I could see if the OTL fuel were needed to get to the moon, but if in a repurposed Apollo CSM esque application, would it be possible to use the LH2/LOX for the SM?

That would require major changes to be made to the orbiter's nose. It would be a heck of alot cheaper to launch the Apollo command module in the orbiter's cargo bay. Mate it to a safer and smaller ('cuz it's not going to the moon) SM, and you have a nice return system for your crew.
Cool, that is what I am looking for on that part. I just think that the SS, if redesigned to not be coming back to Earth (So no wings, TPS, and all the weight that these take up) would be a very different craft, but I have no ideas as to what such an Ortibal Shuttle would look like.

I'm not sure about the answers to your other questions.
fasquardon
Fair enough, and thanks for the input!
 
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Here is another really bad picture:

a1a7mhYl.png


On the left the OTL SS, in the middle I removed the wings, and on the right I moved the cockpit to the rear, and attempted to display a scalable, forward cargo module, atop which would be the notional Apollo esque CSM.

The reason I removed the cargo bay is that, except for it's initial launch, this Orbital Shuttle is never going to be in Earth's atmosphere, so we can place a cargo container forward of the cockpit, and if a recovery vehicle is also needed, then perhaps it can be placed upon the top of the stack.

It could also be possible to have the crew in the RV on the launch, if they can then EVA to the shuttle cockpit upon reaching orbit.
 
Fair enough. I know that the SRB doesn't go so high that we have problems reusing them, but what kind of additional delta V is needed over and above that provided by the SRB? Or is the SRB flight profile just plain not suited for this task? 2 minute burn leaves the CSM 8 minutes shy of orbit? Or something like that?

The SRB dry mass is too high and the ISP of the solid fuel is too low for it to act as a single stage to orbit.

However, running the numbers on an SRB + a Saturn IVB second stage (the IVB is the 3rd stage of the Saturn V), the combined system looks like it could get 15.5 tonnes to LEO.

The vibration you get on shuttle SRBs would mean I wouldn't want to launch people on the thing, but it is a fine cargo launcher.

Could the SM be made to work with something like the SSME's? Or is the OTL the only way they could have worked? I don't know enough to ask a better question, so were the old Apollo SM not just using a less advanced/more toxic fuel? Or were there reasons other than this for the hypergolic (whatever that is) propellent use on the SM? I could see if the OTL fuel were needed to get to the moon, but if in a repurposed Apollo CSM esque application, would it be possible to use the LH2/LOX for the SM?

Hypergolic means propellant that spontaneously ignites when fuel and oxidizer mix. The main hypergolic propellants used in the real world are all closely related chemicals and extremely toxic. As such, the safety issues crop up if one of the SMs spring a leak in the cargo bay or if one of them actually explodes in the cargo bay.

However, hypergolic propellants store for a very long time and rocket engines that use them can be made very simple and reliable - both of which made them the choice propellants for both the SM and the LEM.

Since you are talking about a CSM that would be doing low-orbit work and going up in a cargo bay, then the SM can be smaller and use less storable propellants. You could use LH2/LOX as the propellant, but as I say, you'd need to design a completely new SM.

The reason I removed the cargo bay is that, except for it's initial launch, this Orbital Shuttle is never going to be in Earth's atmosphere

You mean the reason you removed the wings?

on the right I moved the cockpit to the rear, and attempted to display a scalable, forward cargo module, atop which would be the notional Apollo esque CSM.

Why have the cockpit at all if you have an Apollo-esque capsule acting as the crewed portion?

If you are modifying already existent orbiters into space stations, changing the position of the cockpit would be very expensive and I'm not sure what (if anything) would be gained.

Ok, so I keep getting interested in the dang space ATL and discussions, and thought I would start tossing pictures/ideas out here, in no particular order.

And as far as alternate shuttle configurations, this PDF Randy found gives a nice overview of configurations NASA looked into over the years: https://www.aiaa.org/uploadedFiles/About-AIAA/History_and_Heritage/Final_Space_Shuttle_Launches/ShuttleVariationsFinalAIAA.pdf

fasquardon
 

Archibald

Banned
I heard you distress call from the other thread. It shows why space TLs are a little marginal on this site. Space is hard. Let's try a different approach. Ask any question about space in general and I promise I'll try to answer without too much words and with comprehensible pictures. Kind of Saphroneth "gui de to logistics" but for the space program.
 

Archibald

Banned
There are solid fuel and liquid fuel rockets.

Solid fuel is cheap, but performance is bad. Solid fuel is quite similar to rubber and / or fertilizer, and the rocket itself is a big steel tube filled with the solid fuel.

The big SRB on the shuttle flies at mach 5 and then detach and fall.

Speed to Earth orbit is mach 25. It is an absolute minimum. Below that speed the spaceship will fall back into Earth atmosphere and burns up if not protected by a heat shield.

It is possible to build an all-solid-fuel rocket but you need to pile up at least three solids on top of each other. Burn the first solid, drop it, burn the second one, drop it, burn the third and reach orbit, drop it.
 
I heard you distress call from the other thread. It shows why space TLs are a little marginal on this site. Space is hard. Let's try a different approach. Ask any question about space in general and I promise I'll try to answer without too much words and with comprehensible pictures. Kind of Saphroneth "gui de to logistics" but for the space program.
I loved that thread!

Ok, but expect the questions to come in a pretty much randome, disjointed, and non-logical order. And Thanks very much!!!

Ok, so in the end stages of the Apollo program and the starting stages of the SS program time frame:

In OTL we ended up going with an atmospheric re-entry capable Space Shuttle, which meant that a heat shield was going to have to be able to withstand the forces of re-entry, and that this heat shield (the TPS I think it was called) was going to have to be launched into orbit each and every time. So a significant part of the mass of what was going into orbit was NOT going to have any function there, and this was going to be the case EVERY launch. Is this correct, and why was this approach choosen?

As an Alternative, could we have gone for an Orbital Space Shuttle, that doesn't need the heavy and troublesome TPS (Nor aerodynamic form --- wings), but instead had just the components that would actually be needed for it's operations in Orbit? While I am asking this, maybe a quick rundown of what these things are would be helpful.

Here is a extremely crappy (But the best I can do) image of a notional OSS (Orbital Space Shuttle),
XGnYJA0l.png

stripped down to just the SSME (Space Shuttle Main Engines) and the cockpit. Another random thought that just went through my empty head is, with the revised launch system, where by the main External Tank (ET) is going to be used to have both side straddle and stackable payload variants, depending upon whether or not you are sending up an OSS, putting SSME on the botton of the ET, as seen in the wiki for the Space Launch System (SLS), would the OSS even need to have the SSME. or could it instead make do with just the Orbital Maneuvering System (OMS) engines?

I will have many more questions later, but for now lets run with these.
 
There are solid fuel and liquid fuel rockets.

Solid fuel is cheap, but performance is bad. Solid fuel is quite similar to rubber and / or fertilizer, and the rocket itself is a big steel tube filled with the solid fuel.

The big SRB on the shuttle flies at mach 5 and then detach and fall.

Speed to Earth orbit is mach 25. It is an absolute minimum. Below that speed the spaceship will fall back into Earth atmosphere and burns up if not protected by a heat shield.

It is possible to build an all-solid-fuel rocket but you need to pile up at least three solids on top of each other. Burn the first solid, drop it, burn the second one, drop it, burn the third and reach orbit, drop it.
Hence the three stages for the Saturn V? And the SS made use of SRB's to give the ET/SS combo the added ommmph to reach orbit by burning the liquid fuel stored in the main tank. Sweet. Did the liquid fuel ALL get used up in the ascent/orbital injection burn, or was there some left over? Could one put excess fuel into orbit and make use of it at a later time? Or does this question have a complex answer? I suspect that different fuels would have different properties, and keeping them viable for prolonged time frames, in orbit, might de difficult and need to be on a case by case basis. If storage in orbit is possible (I just blindly assumed that fuel and OSS's could be), what would possibly help extend their useful lifetimes?

I have heard of something called a "Power Module", that could extend the OTL SS's time in orbit a good deal. The article I read mentioned something about the SS 'fuel cells' as being the limiting factor for in orbit duration stays, could you shed some light here?

I should probably also ask, storage in a powered vs unpowered state, what can be in which state, and which is better?
Also, would having a "storage garage" in orbit be helpful or not? And would both powered and unpowered versions be good or not?
 
Also, as far as the long term orbital storage and environmental considerations go, pressurized or unpressurized, heated or unheated? Any other questions along these lines I missed?
 
In OTL we ended up going with an atmospheric re-entry capable Space Shuttle, which meant that a heat shield was going to have to be able to withstand the forces of re-entry, and that this heat shield (the TPS I think it was called) was going to have to be launched into orbit each and every time. So a significant part of the mass of what was going into orbit was NOT going to have any function there, and this was going to be the case EVERY launch. Is this correct, and why was this approach choosen?

TPS is just an abbreviation for "thermal protection system" - all spacecraft that return to Earth need one. For Apollo, it was an ablative covering on the back of the capsule ("ablative" meaning it wears away during re-entry), for the shuttle it was a mix of ceramic and carbon/carbon tiles which did not wear away during re-entry (theoretically making the shuttle easier to re-use, but in practice the tiles needed to be laboriously checked after each re-entry).

The reason why the shuttle protected everything with tiles is because the nose needed to protect the humans, the tail needed to protect the engines (since engines are a big part of the equipment cost of a rocket, so bringing back the engines for re-use was a big goal of the shuttle), the cargo bay needed to be protected because the original plan was that the shuttle would not only take stuff up, it was also to bring stuff back down again (intended to allow satellites to be reconditioned and experiments to be carried down).

would the OSS even need to have the SSME. or could it instead make do with just the Orbital Maneuvering System (OMS) engines

The OSS does not need the SSME. The SSME is so powerful it is only useful for getting off of the Earth.

Did the liquid fuel ALL get used up in the ascent/orbital injection burn, or was there some left over?

No rocket devised by man is able to use all of its fuel (kinda like how you can never get out the last drop of coke in a can). The ET did indeed still have some fuel left in it once it was used up.

Could one put excess fuel into orbit and make use of it at a later time? Or does this question have a complex answer? I suspect that different fuels would have different properties, and keeping them viable for prolonged time frames, in orbit, might de difficult and need to be on a case by case basis. If storage in orbit is possible (I just blindly assumed that fuel and OSS's could be), what would possibly help extend their useful lifetimes?

Liquid hydrogen is a real pain to store in orbit. Since it needs to be so cold and can leak right through solid sheets of metal in the right conditions, you need quite a complex satellite to be a LH2 fuel dump.

Liquid oxygen is also a pain to store in orbit, but far, far less of a pain. You just need to put a shade between the LOX tank and the sun and it will be cold enough to keep the oxygen liquid.

Hypergolics like nitrogen tetroxide and hydrazine store in space quite happily and the Soviets even managed to pump these fuels from one space craft to another (how about that for in-flight fueling!)

I have heard of something called a "Power Module", that could extend the OTL SS's time in orbit a good deal. The article I read mentioned something about the SS 'fuel cells' as being the limiting factor for in orbit duration stays, could you shed some light here?

The shuttle used LH2/LOX fuel cells that reacted the two together to make water. Since there were limited amounts of fuel for the fuel cells, the shuttle could only run them for so long.

fasquardon
 

Archibald

Banned
Solids are good for starting because they have enormous, brute thrust. Liquid-fuel engines thrust less, but have more energy and performance.

Yes, Saturn V had three stages.

The first stage used kerosene because (somewhat like solid fuel)it has best performance at lift-off.

The second stage used liquid hydrogen, which is the best energy and performance.

Saturn V could loft thing into Earth orbit with two stages (Skylab ).

The third stage was needed to push Apollo from Earth orbit toward the Moon.
 
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Archibald

Banned
Rule number 1 of space travel: wherever you are in the universe, you're always in a gravity field - from Earth to galaxies.
It is Earth gravity > Sun gravity > Milky Way gravity

A gravity field is like a flat surface, and things like planets or stars or galaxies are carving holes into that surface - they sat at the bottom of a gravity well or gravity pit. The bigger the object, the steeper and deeper the gravity pit.

By rocky planet standard Earth is pretty massive, so the gravity pit is deep. To make matter worse our planet has a thick atmosphere.

How do you go from Earth surface to Mars surface ?

First, climb out of Earth gravity well and escape the pull of Earth.

Then you fall into the Sun gravity field - basically an orbit around the Sun.

Then you want Mars to catch you. For that you need to fire a rocket engine and brake heavily to fall into Mars own gravity pit. That pit is much less steeper than Earth's, because Mars is much smaller. It is possible to brake into a Mars orbit, or to fall straight to the surface - hopefully with parachutes and retrorockets for a soft landing.

Then the return: climbs out of Mars gravity well (much easy) then escape the pull of Mars, cruise in a solar orbit for some time then brake at Earth to return to the planet surface.

If the braking near Mars doesn't work, the ship flyby Mars like a cannonball and then remains in orbit around the Sun. It fly past Earth, then Mars, over and over. There are space junk that has been in orbit around the Sun for decades.

So basically space travels consists of painfully climbing out of a gravity well to fall into another.

The solar system looks like this (you can see that, Jupiter being enormous, the gravity pit is pretty huge)

gravity_wells.png
 
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Rule number 1 of space travel: wherever you are in the universe, you're always in a gravity field - from Earth to galaxies.
It is Earth gravity > Sun gravity > Milky Way gravity

Snip

gravity_wells.png
Image doesn't show up, at least for me, so I cannot comment on it. OTOH, working from memory, Venus has about .98G, Mars and Mercury both have .38G, while Luna has but .16G, so I would expect that space based manufactoring would have basically two incarnations initially, those being "Zero G" in orbit (Perhaps aka "Micro G"), and Low G, on the Moon and later Mars.

Naturally, I don't want a space program that fails to achieve at least the initial colonization and industrilization, of LEO, LLO, and Lunar surface operations before I kick the bucket.
 

Archibald

Banned
I'm sorry that the picture doesn't show. I can see it -
https://www.explainxkcd.com/wiki/images/f/f9/gravity_wells.png

So in order to get into orbit around Earth you need a speed of Mach 25+
Most of military aircrafts flew at Mach 2.5, exactly 1/10th of that.
Which is why rockets are so unlike aircrafts.
There is also the case of Earth thick atmosphere.
Mach 25 = 7.3 km/s
+drag losses (boring a hole through the atmosphere) = +2 km/s
Total 9.3 km/s just to go into orbit around Earth
- NOT escape from it.
Earth escape is even worse: nearly 12 km/s ! (from memory: 11.7 km/s)
(For the sake of comparison SpaceShip Two top speed is 1 km/s)

Now an analogy about why SSTO (to Earth orbit, not even escape so 9.3 km/s) is so hard.

Imagine a car that weight 1 metric tons (1000 kg)
Now that car gas tank is filled with 920 kg of gasoline.
What car is that ? 920 kg of gasoline - plus the mass of the tank around the gasoline, and of course the car around that tank, plus you, your family and luggage. Well, you are only allocated 80 kg for all this.

That's how all-rocket SSTO works. 92% of the lift-off mass is propellant by themselves (liquid oxygen + liquid hydrogen, but different propellants are not really better).
You are allocated 8% of the total lift-off mass mass for the tank to get around the propellants - plus everything else, notably a decent payload to orbit, and of course the recovery gear.

That's why rocket stage: they throw away unuseful mass in roder to reach orbit (mach 25 or more).
 
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Archibald

Banned
There is a very counter-intuitive thing with spaceflight.
The V-2 rocket flew at the edge of space, peaking at 50 miles.
But top speed was around mach 5 - far, far from Mach 25. So the V-2 couldn't haul itself or a payload into orbit.
 
As much fun as it is to look at hardware, the better question is mission, the Shuttle was built to fulfill a purpose, that mission drove the multitude of compromises necessary to arrive at the end result. It appears that the Shuttle was built to take things into orbit, in particular larger numbers of passengers, retrieve and return stuff from orbit, support construction in orbit, and mixing these to be the link between Earth and a station in orbit, take away the station and Shuttle became a tool in search of purpose. That said it appears to me the heavy lifting could have been done by a dedicated lifter, if you remove the need to return satellites from space, then you get a crew transporter as it more focused mission. Here that seems part of the re-thinking, either a "flyable" craft or a capsule capable of re-entry, aka Big Gemini. Had the USA kept Skylab or something like it aloft, would not Shuttle have been two parallel programs? A dedicated follow-on lift system and a focused crew shuttle? Could NASA have done better improving say Saturn I as a heavier lifter to LEO and revisiting Big Gemini as its crew shuttle? Or was the need to build a "game changer" too strong a flame for our moth?
 
I would, had I been the MFIC of the US space program, not have gone with the idea of a reusable shuttle like OTL, rather I would take them into orbit and there they would stay. The crew return vehicles would be modern equivalents to the old Apollo capsules, the OTL ET would have the SSME's, and would be retained in orbit after launch, and would come in both stack and side straddle variants, with the possibility of a much enlarged version down the road. The SRB would be pretty much as OTL.

So basically, each launch that had an OSS would:
Leave the ET and OSS in orbit, along with whatever mission payload was sent up, and both SRB and the CRV would return to Earth.

A cargo mission would:
Leave the ET and the payload in orbit, while the SRB returned to earth.
 
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