Shutte ET as ISS module

RobertDyck · 2015-01-14 15:58:10

The issue of keeping Shuttle external tanks on-orbit came up a couple days ago. I pointed out using a tank as a station or station module would require extensive modification. Let's explore how much. What would it take?

First we have to assume Shuttle is flying again. All the orbiters still exist, with engines removed and in museums. Assume the powers that be could be convinced to restore one to flight. That alone could be a long debate, but for simplicity assume no Shuttle modifications, just restore them as they last flew. And preserve one mobile launch platform as-is. And restore the static service structure of one launch pad. Could the pad for SLS be preserved so the only difference is MLP? One for Shuttle, a different one for SLS?

Ok, now the fun stuff. The ultra light weight external tank, as the Shuttle last flew, is made of lithium aluminum alloy, and insulated with spray-on foam. Some foam breaks off during launch. And that foam is not designed to be durable; when exposed to intense UV light in space (above the ozone layer) it will degrade rapidly. And exposure to vacuum, and micrometeoroids. So that foam is not adequate for a station module. What do ISS modules use for thermal and micrometeoroid protection? I remember reading something about a blanket. Do all modules have that blanket? Could we replace the spray foam with that blanket over the entire surface of the ET? How heavy would that be? Could we design a lighter thermal/micrometeoroid protection that can withstand hypersonic air during launch, and endure in LEO for the entire life of the station? Exactly how heavy is the current foam, and exactly how heavy per unit area is current ISS module protection?

Next assume a CBM hatch installed on the very bottom of the LH2 tank. The inner surface would have to be smooth, to permit propellant flow onto the hatch. So no "lip" for the door frame that would prevent propellant flow. A custom door could be installed during launch, one that would act as a propellant sump for the siphon. That door could be replaced on-orbit with a standard CBM door. The door during launch doesn't have to serve as a station door, just as a sump for launch. The top of the LH2 tank would also require a CBM hatch. Again, the door could be light weight, replaced on-orbit. And the bottom of the LOX tank would also require a CBM hatch. The LH2 tank has a siphon that drains up, but the LOX tank drains down directly into the propellant feed line. So the LOX hatch will have the LOX siphon integrated right into it.

Assume the Shuttle will launch with its cargo hold completely empty. Just 2 astronauts: pilot and co-pilot. Nothing in the mid-deck cupboards. Assume the internal airlock, the one without the APAS hatch, because it's lighter. It could be mounted inside the mid-deck, or outside in the cargo hold, but the point is the lighter airlock. A safety rule is the Shuttle must carry at least one EMU spacesuit, in case the cargo bay doors don't close. If that ever happens, an astronaut will go out and close them by hand. No RMS (CanadArm). So this is the Shuttle stripped down to minimum. And Shuttle Endeavour, because that one was lightest. The Shuttle will deliver this custom ET to LEO, then return to the Cape. And assume it's delivered to the same inclination as ISS, but only to 185km altitude. This assumes the ET will be extremely heavy.

A second Shuttle mission will launch with a standard ET, and that ET will be discarded to burn up and crash in the ocean. Just like any other Shuttle mission. It will rendezvous with the custom ET delivered by the first launch. This second mission will carry equipment in its cargo hold, and will carry CanadArm. Grapple the ET. An astronaut in an EMU spacesuit will enter the tank and eliminate any residual propellant. On Earth we would use pressurized air, but in vacuum? Perhaps just a radiant heater to boil any residual liquid while the hatch is open to space. Remove the LH2 siphon and anti-vortex baffles. Drift to the inter-tank, remove the temporary hatch doors, and remove the LOX feed line. Just the feed line from the LOX siphon to the inter-tank wall. The feed line outside the LH2 tank can stay. Then install ventilation ducts and electrical conduits between tanks. Yes, fittings in the tanks would have to be pre-installed. Then install a pressure tight tunnel between the LH2 top hatch to the LOX bottom hatch. And install CBM hatch doors. Install equipment in each tank for temperature control. Install radiators on the outside, and connect plumbing. Install a rack inside with pressurized air to fill both tanks. Close and seal all hatches, leave, and pressurize the new module. Check pressure to ensure no leaks.

Then attach a propulsion stage to the aft CBM hatch. Then the Shuttle will de-orbit, return to Earth. Once the Shuttle is clear, the propulsion stage will raise orbit to ISS and rendezvous. The station RMS (CanadArm2) will grapple the ET, and slowly bring it in to berth with a station CBM. Yes, a module that big will move much slower than a standard station module. Because the propulsion stage will be attached to the tank CBM, the propulsion stage will have to detach and depart once the station arm has grappled it.

One reason for using CBM and not APAS, is so equipment racks can pass through. The tank will be installed with almost nothing inside. Just racks with equipment for temperature control and air tanks for initial fill. Everything will have to be installed. Mounting hard points would be pre-installed on the inside of the tank, but nothing more.

ISS currently has no habitation module. Life support equipment is spread between Node 3 and the Destiny science module. And sleeping quarters are spread across the station. This would make one incredible living space. Instead of a standard module such as Destiny, 4.2 metres diameter and 8.4 metres long, the LH2 tank is 8.4 metres diameter and 29.6 metres long. That includes the dome ends. And the LOX tank is tear-drop shaped, 8.4 metre diameter at its widest and 16.6 metre long. Move American living space into THAT! Move existing life support equipment and sleeping quarters into the ET. You would have room for some REALLY nice upgrades.

RobS · 2015-01-14 16:07:38

I suppose my first question, Robert, is what does the SLS use? I suppose it's rather like the shuttle main tank. Why not ask about that? It's more likely to fly.

RobertDyck · 2015-01-14 16:08:55

If Shuttle was flying again, then we could install the Centrifuge Accommodations Module, and two flights to install the Russian solar arrays: Science Power Platform.

RobertDyck · 2015-01-14 16:18:24

RobS wrote:

I suppose my first question, Robert, is what does the SLS use? I suppose it's rather like the shuttle main tank. Why not ask about that? It's more likely to fly.

True. But it's an old idea, I thought at least Mark Friedenbach would like to explore. And I don't see how SLS core stage could achieve orbit. The upper stage could. It wouldn't be as big, but would have enough launch mass for equipment to be pre-installed. Then that raises the issue of equipment surviving immersion in liquid hydrogen. Early 1970s vintage electronics could; they wouldn't operate until warmed, but were sufficiently robust to survive. I don't think modern electronics would survive. Solid materials could be made of fluoropolymers such as Teflon and Goretex instead of cheap plastics, because fluoropolymers can survive cryogenic cooling. Sertain polyimide plastics can survive. Instead of glass light bulbs you would use transparent fluoropolymers. Glass can survive liquid hydrogen, but only if temperature change is very gradual. Rapid temperature change will cause glass to shatter.

Last edited by RobertDyck (2015-01-14 16:55:19)

JoshNH4H · 2015-01-14 20:29:21

For equipment inside the pressure vessel, you would probably want to insulate it and heat from the inside to ensure that it stays at some minimum internal temperature. The power usage could be pretty small if it was insulated enough and then the insulation could be removed by crew and the components installed where they are to be used.

RobertDyck · 2015-01-14 22:54:02

Well, we don't even know what the upper stage of ISS will be like. Several sources call it the "Dual Use Upper Stage", and say it's pronounced "Duce". And they say SLS with 5-segment SRBs and DUUS, will be able to lift 104.5 metric tonnes to LEO. They call this "SLS Block 1B". With advanced boosters, either solid or liquid, it will lift 130t. But there's already proposals to change re-design the upper stage, the new one called Exploration Upper Stage (EUS), able to lift 118t with 5-segment SRBs.

Wikipedia, confirmed upper stages:
Block 1: modified Delta IV 5 meter Delta Cryogenic Second Stage (DCSS), referred to as the Interim Cryogenic Propulsion Stage (ICPS)
Block 1B: DUUS or EUS. Currently planned to use 4 RL10 engines.

Various documents on the web describe DUUS or EUS as 8.4 metre diameter, with a bulkhead between LH2 and LOX tanks. Or separate tanks, with the LOX tank different diameter, supported by struts. If the upper stage is 8.4m diameter with bulkhead, then we can use it as a self-launching station module. If it's separate tanks with different diameters, then no.

This discussion is already derailed. Well, others have complained when they started something and I challenged the premise. That has been done to me before, and is now. I wanted to show that a Shuttle ET as a useable module in LEO required so much modification that Shuttle wouldn't be able to carry anything else. And to show even that would barely make it to orbit. However, doing so would be one fine module!

Several Mars Society members (at times myself included) had argued that if Shuttle was decommissioned, then NASA would have sufficient funds to send humans to Mars. Well, Shuttle has been cancelled. But funds had been directed to Constellation instead. Now that Constellation is cancelled, funds are directed to SLS/Orion. And no real mission for them. We would have been better off with Shuttle.

Anyone want to work on the Shuttle ET module for ISS?

kbd512 · 2015-01-15 03:21:10

I think that the STS program should be re-activated immediately and all orbiters refurbished and upgraded for a specific purpose, retrieving SLS hardware and orbital assembly and servicing of payloads launched on SLS.

Somehow the various contractors will make Orion's development and use every bit as expensive as the far more capable Space Shuttle. Orion was developed for a manned lunar program that no longer exists. It has no purpose for a Mars mission. The proposed lunar fly-by stunt is just that.

If it were up to me, I would follow most of the recommendations proposed for the Space Shuttle upgrades. Specifically, the avionics and fuel cell upgrades, landing gear improvements for greater landing weight, and channel wall nozzles for the RS-25's are all worthy of development dollars. Additionally, to eliminate the insane amount of manual labor that refurbishment of the orbiter TPS requires, a robotic TPS refurbishment and inspection capability should be developed. Cancellation of Orion would make available the required funding for the necessary Space Shuttle upgrades and operation.

Here's my proposal for a re-activation of the STS program:

Presumptions:
I presume no more than 2 SLS launches per year and an equivalent number of STS launches to retrieve the RS-25's. I also presume that work on the Dark Knight boosters moves forward to lower the cost of the SRM's and increase their performance. The general idea is to remove the most costly aspects of SLS (expenditure of expensive reusable hardware) and STS (labor intensive reusable components) and increase the flight rate of common hardware.

Problem:
The RS-25E development programs have to contend with the fact that RS-25 was designed for reuse and is way too expensive for use in expendable launch vehicles.

Solution:
SLS would become the cargo-only rocket that it always should have been, STS would infrequently transfer crew and cargo to ISS and space exploration vehicles, and it would return the costly RS-25's from SLS rockets.

Pre-req's:
The SLS engine barrel would require a slight redesign to separate it from the tankage and subsequently circularize its orbit for retrieval of the RS-25's.

The RS-25 would require a redesign to permit easy removal of the nozzle extension from the powerhead.

Intended Use:
The first ISS module that a STS return-to-flight mission should carry would be a machining module to repurpose the aluminum from the engine barrel to eventually construct space station module shells in orbit. It demonstrates the capability to use largely autonomous machining centers operating in microgravity to have them turn SLS scraps into construction stock for ISS or spare parts for space exploration hardware. At a later date, if it is possible to boost the entire core stage into orbit, then the capability to entirely reuse the overwhelming majority of SLS flight hardware becomes possible.

Conop:
Each STS mission would follow a SLS mission to transfer supplies or modules to ISS, take space exploration crews to their space exploration vehicles docked at ISS, and retrieve RS-25's from SLS missions to repurpose the materials from the engine barrel and eventually the tankage, too.

Goal:
ISS would finally be a space exploration mission support tool. The machining unit would turn the microgravity experiment into a space-based manufacturing facility to construct mission hardware from SLS remnants, and a staging area for space exploration crews/vehicles.

Conclusion:
I have no idea what the technical challenges would be with this solution or if it's reasonable, but the payload capacity is there if the landing gear receive the upgrades.

kbd512 · 2015-01-15 03:51:24

Here's why I want to do this.

- Increase flight rate to maintain workforce and its proficiency at manufacturing flight hardware

- Skip RL-10/J-2X/DUUS/EUS and other upper stage acronym soup chemical engine development to ensure funding for gas core nuclear rockets, nuclear power solutions for exploration vehicles, and methane powered engines for Mars landers is available

- Gas core nuclear rockets eliminate the need for heavy aeroshells required for risky aerobraking maneuvers to achieve Mars orbit and the attendant weight of propellant required for Mars orbital insertion, thus keeping individual SLS payload weights within a margin that SLS with advanced SRM's could realistically achieve

- Ensure continued availability of funding for advanced long term storage of cryogenic propellants for the nuclear rockets

- Provides both reason and utility for the continued existence of ISS

- NASA could partially fund development of Dragon Rider for propulsive landing of crew on Mars so the cargo landers would not have to be man rated or require separate designs for cargo-only versus crewed landers

I still want to retire STS and SLS, but at a time when their capabilities are no longer of utility to our manned space program.

RobertDyck · 2015-01-15 12:04:55

The core stage of SLS will never achieve orbit. It's a big dumb rocket. Even though SSME was designed to be reusable, SLS will never be able to deliver its core stage engines to orbit.

Second, SLS practically is the Ares rocket from Mars Direct. In fact, from what's posted online, designers are considering 5 main engines for block 2. So with 5 SSME in the core stage, a pair of J-2X for the upper stage, and a pair of SRBs, that is Ares. The only difference is 5-segment SRBs instead of 4-segment. One option I wish they would consider is 5 SSME with 4-segment SRBs. That skips the vibration problem with 5-segment boosters.

One design feature is to use 4 RL-10 engines instead of a pair of J-2X. Interesting: J-2X produces 1307 kN thrust (133,276.9 kg force), Isp=448s. RL-10 produces 110 kN thrust (converts to 11,216.878 kg force, but you should round off to 3 significant figures), and Isp = 450 to 465.5 seconds. Why is Isp in vacuum a range? So 4 RL-10 engines provide much less thrust, but a little better Isp. If you burn those engines longer, could it provide more delta-V? That's one thing they're talking about.

Separating cargo from crew is generally a good idea, but we need a launcher for crew. SLS is that launch vehicle.

kbd512 · 2015-01-15 14:32:55

RobertDyck wrote:

The core stage of SLS will never achieve orbit. It's a big dumb rocket. Even though SSME was designed to be reusable, SLS will never be able to deliver its core stage engines to orbit.

Wait. What? I thought SLS Block I without an upper stage was supposed to push 70t to LEO. Is that incorrect?

RobertDyck wrote:

Second, SLS practically is the Ares rocket from Mars Direct. In fact, from what's posted online, designers are considering 5 main engines for block 2. So with 5 SSME in the core stage, a pair of J-2X for the upper stage, and a pair of SRBs, that is Ares. The only difference is 5-segment SRBs instead of 4-segment. One option I wish they would consider is 5 SSME with 4-segment SRBs. That skips the vibration problem with 5-segment boosters.

Would composite casings mitigate the vibration problems with the 5-segment design?

RobertDyck wrote:

One design feature is to use 4 RL-10 engines instead of a pair of J-2X. Interesting: J-2X produces 1307 kN thrust (133,276.9 kg force), Isp=448s. RL-10 produces 110 kN thrust (converts to 11,216.878 kg force, but you should round off to 3 significant figures), and Isp = 450 to 465.5 seconds. Why is Isp in vacuum a range? So 4 RL-10 engines provide much less thrust, but a little better Isp. If you burn those engines longer, could it provide more delta-V? That's one thing they're talking about.

From an engineering complexity standpoint, is there a good reason why right-sizing the core stage design to achieve the desired throw isn't preferable to adding a stage atop the core stage? Most efficient? Obviously not, but what insane amount of money will be required for a man-rated second stage?

RobertDyck wrote:

Separating cargo from crew is generally a good idea, but we need a launcher for crew. SLS is that launch vehicle.

I agree on the first point, but SLS need not carry crew. We have existing hardware to blow mad money on LEO transport service. If each Orion/SLS flight costs just as much as a Space Shuttle flight or more, then Orion has no purpose, apart from preventing development of real space exploration hardware.

RobertDyck · 2015-01-15 16:27:54

kbd512 wrote:

Would composite casings mitigate the vibration problems with the 5-segment design?

I don't think so. My understanding is this is a harmonic problem. Just as a pipe organ produces sound notes with the same wave length as the pipe, the SRB will produce vibrations with the same wavelength as the total length of the booster. Plus harmonics: 1/2, 1/3, 1/4, 1/5th wavelength. Always 1 over an integer. If this reinforces vibrations from burning fuel, then you have a problem. A 4-segment SRB did not have this problem, but 5-segment does. The solution is either make the 5th segment shorter, so the total length is not a harmonic of the natural vibration of burning fuel, or make the top segment a cone rather than a cylinder. Either way, the 5th segment is smaller. But smaller means less thrust, and custom manufacturing means higher cost. Lower prerformance and higher cost, at the same time? They don't want that. So they pretend they don't have a problem. Closing eyes and plugging ears! La la la la la!

kbd512 wrote:

...SLS need not carry crew. We have existing hardware to blow mad money on LEO transport service. If each Orion/SLS flight costs just as much as a Space Shuttle flight or more, then Orion has no purpose, apart from preventing development of real space exploration hardware.

Um, yea. That's the point. We can transport crew to ISS with Dragon Rider. The crew version of Dragon is a lot less expensive. That's not the point. We need SLS to send Mars Direct to Mars. Or an alternative mission architecture. All require about equivalent launch vehicle.

Impaler · 2015-01-15 17:12:21

I think this thread got off to a very bad start by mention a 'return' of Shuttle, that's just insane and is sucking up all the LOX.

If you kept the discussion to just how to make use of the External tank in orbit as might have been done then we would be doing some armchair engineering on some dead hardware but it would still be a decent discussion so long as we all acknowledge that it's not going to happen but rather represents some could-have-been. Roberts idea in the opening post is probably the best that could be done with the tank, some combination of pre-installed hatches, and on orbit rework with new air-locks installed onto the hatches.

Problem is that we don't get 'habitats' from this we get 'giant zero-g playrooms', without all the mass of equipment that forms a habitat their is no functionality to the large pressure vessel that a tank is. Just because current space-stations provide low volume per person and are a bit cramped dose not mean we can get a good habitat by providing only volume, just as we can't replace a cramped NY condo with an unfurnished aircraft hangar. Without many many more tons of equipment the huge volume of the tank dose not increase the population of ISS.

This is a major issue with tank-habitat conversion and I also have it with Bigelow concepts, the mockups so far released make poor use of the volume because they are designing the things to maximize volume and they look to be under equipped with all the other things necessary to make a living space (life-support, water, sanitation, galley etc etc). Now IF Bigelow had a plan for actually installing a furnishing this equipment then all would be great, but everything we have seen so far is 'monolithic' with all the furnishings inside the core of module, and that core is much smaller in volume and mass then what could be put into a rigid Destiny module type thing.

What inflatable and 'wet' habitat concepts need is outfitting by something like the Leonardo Pressurized Logistics Module. It can be packed solid with equipment racks and then connected by CBM to allow that equipment to be moved into the station space and installed. When furnishing a really large space we would need to include deck-floor panels. Then the pressure vessel just needs to have an few 'frame' rails and conduits for cabling for all these furnishings to attach too, which would be easy enough in an inflatable and even easier in a propellent tank. This may require several flights of equipment for every flight of a pressure vessel as we would expect and hope, the big pressure vessel is more mass efficient per unit volume, so as a percentage of total it drops, but their is no point unless your going BIG, like high double digit populations.

What you want to end up with is something MORE cramped then ISS Destiny module which has an excessively large 2m x2m hall through the middle, rather you would want to have hallways only 2m x 1m, the minimum size a person can comfortably go through and what much of the Russian Functional Cargo Block looks like inside. If we have a huge volume to fill then we just a whole bunch of lateral decks and pierce it through with multiple hallways. The same way a hotel or cruise ship is built on Earth. Allocate a few 'rooms' for gathering and then allocate ALL the rest for equipment and bunk space. Now you're going to have the ability to house people at enough of a density that your big volume is actually getting you more population which was the point of all this.

SpaceNut · 2015-01-15 19:53:25

We did have and it may be still here but in case went searching.... Energy cost of bringing the space shuttle external tank to orbit

Relevant thesis: ANALYSIS OF PARKING ORBITS FOR A STS EXTERNAL TANK IN LOW EARTH ORBIT, J. E. Cross, 1990 (PDF) and another paper: Evaluation of Aerodynamic Drag and Torque for External Tanks in Low Earth Orbit, W. C. Stone, C. Witzgall, Journal of Research of the National Institute of Standards and Technology, 2006 (PDF) – TildalWave

How much fuel is used for a Space Shuttle launch?

Re-using Today's Rockets' Spent Fuel Tanks in Orbit

After the Boosters are detached early in the flight, the Main External Tank fuels the Shuttle Orbiter tail engines at full thrust to gain the high speed required for orbit. When more than 97% of orbital speed is attained, the MET is detached from the Shuttle Orbiter and directed to cross Earth's atmosphere to burn up (Skylab-like) with remnants falling into a remote section of the Indian Ocean. Notably, the MET, when separated from the Shuttle, still has some hydrogen and oxygen in it. This leftover fuel is abot 1000 kilograms (roughly 2000 pounds) or 1 ton of hydrogen, and about 6,000 kilograms (13,000 pounds) or 6 tons of oxygen, which is 1% of its liftoff fuel. It also has 500 kilograms (245 pounds) of nitrogen (a refrigerant).
The hydrogen and oxygen are useful combined as water (7,000 kilograms, or 15,000 pounds per tank). Humans and plants need water, nitrogen, oxygen, and hydrogen.

kbd512 · 2015-01-16 00:12:41

The reactivation of STS need not be a death knell for space exploration. We can retain STS to do what little good it does, have commercial crew and cargo transfer vehicles to service ISS, use ISS as an orbital manufacturing facility to reclaim the materials in the STS and SLS ET's, and use SLS to lift cargo required for a real manned space exploration program. Consolidation of facilities and elimination of non-essential programs is the key.

The cost of STS was driven by permitting contractors to operate support facilities all over the country. If NASA had mandated that all flight hardware be built, tested, and launched from one location, then the number of employees required to maintain facilities, contractor travel costs, and hardware transportation costs plummet. Head count for redundant operational support also plummets.

Man-rated flight hardware that's available right now and not years into the future, if and when it's development is completed- something that is entirely dependent upon political support, is what we should use. NASA doesn't have a manned space program right now because the obvious issues with STS, Ares/SLS, and Altair/Orion were ignored.

Although some useful upgrades were incorporated into STS, a lot of equally important cost reduction measures, head count reduction measures by any other name, were never implemented. The orbiter TPS immediately comes to mind. If JPL can design robots that drive around on Mars, then it can sure as heck design a robot that lays ultra-lightweight sand bricks back here on Earth.

There are some limited instances where it's desirable to have a crew service a payload, and STS was designed for that. To my admittedly limited knowledge, NASA doesn't have the technology required to travel back in time and smack the decision makers who created requirements that forced STS to be the kluge that it was upside their heads. So, as long as we have lemons we make lemonade.

The two "accidents" in the STS program were more willful ignorance on NASA's part that resulted in destruction of flight hardware. Those kinds of things happen when you ignore your engineers.

If LANL can fabricate a new class of reactors for satellite power in less than a year and for less than a million dollars, then for a few billion not wasted on redundant capsule systems, I'm quite certain that a gas core reactor is in the cards for us. That's where I want our development dollars directed. VASIMR and other NEP technologies may be entirely feasible once nuclear fusion is perfected, but let's not hold our breath waiting for that to happen.

Getting back to the question posed in the OP, can we use the uber gas cans as raw materials for construction of ISS modules or Mars landers from an orbital manufacturing facility aboard ISS? I think so. If the money has already been expended to push the ET's to orbital velocity, then dumping them into the ocean is egregiously wasteful. So what if some gas is required to circularize the orbit? The gas can still has around 1% of the gas in it at MECO. Is it an impossible engineering task to develop thrusters to convert that residual to a circular orbit?

Impaler · 2015-01-16 00:46:21

This is crazy talk, their is nothing to 'reactivate' the Orbiters can not be plucked out of museums and just flown, they depend on ARMIES of technicians which have been scattered to the winds, the people who designed and built it all have retired or DIED. All that money has been reallocated to NEW armies of technicians working on new vehicles, none of their new skill sets are transferable even if some political will existed to try to do that, but in fact all political will is for the current program not to try to return to Shuttle. And if we COULD somehow summon the political will to divert from the current SLS/Orion why in the name of all that is Holy would we actually want to return to a vehicle which was a complete failure on EVERY single desired performance metric.

Shuttle was DANGEROUS, EXPENSIVE and INFREQUENT, the SLS/Orion while it is likely to be just as expensive and infrequent will at least be safer by virtue of being a capsule with launch abort systems.

RobertDyck · 2015-01-16 01:47:39

The Washington Post published this article: NASA’s $349 million monument to its drift
The article tries to make this sound stupid. They completed a test stand for an engine that was cancelled years ago. What they don't say is that engine is the J-2X. Yes, Constellation was cancelled in 2010, but J-2X is intended for the upper stage of SLS Block 2. So it isn't stupid.

The reason I raise this: it tests a rocket engine in vacuum. Great! So they can do that. Now design a test stand that does the same thing, but for an open cycle gas core nuclear thermal rocket. That test stand is the obstacle. Since they know how to build one that contains rocket exhaust, it's time to proceed.

RobertDyck · 2015-01-16 02:13:06

kbd512: When Shuttle was flying, I tried to tell a couple Shuttle engineers my idea to save cost. I noticed the windshield was hand ground every flight to remove micrometeoroid pitting. They didn't use power tools, it was hand ground. Very labour intensive. My idea was to replace the glass with ALON: Alumino-Oxy-Nitride. That's a transparent ceramic developed under contract for the US army in the 1980s for windows of tanks. It's designed to be bullet proof. Since it can withstand dramatic impacts, that should eliminate micrometeoroid pitting. Both engineers told me they had ideas to reduce labour and expense processing Shuttle. And both engineers told me corporate executives told them no; that their goal was to maximize cost to pay employee salaries and corporate profit. So people far more qualified than you or me came up with ideas, but were told to shut up.

The first link posted by SpaceNut provides numbers for energy needed to bring ET to orbit. The first post says 1,514 kg of additional OMS propellant, reducing payload by that mass. The second post calculated reduced payload by 5,280.5 kg. And both calculate based on low altitude science orbit, not ISS. And that's a standard ET, not one modified to be a station module.

kbd512 · 2015-01-16 02:22:21

Impaler wrote:

This is crazy talk, their is nothing to 'reactivate' the Orbiters can not be plucked out of museums and just flown, they depend on ARMIES of technicians which have been scattered to the winds, the people who designed and built it all have retired or DIED. All that money has been reallocated to NEW armies of technicians working on new vehicles, none of their new skill sets are transferable even if some political will existed to try to do that, but in fact all political will is for the current program not to try to return to Shuttle. And if we COULD somehow summon the political will to divert from the current SLS/Orion why in the name of all that is Holy would we actually want to return to a vehicle which was a complete failure on EVERY single desired performance metric.

IIRC, at its peak there were fewer than 30,000 people devoted to STS.

The people who designed Soyuz are all retired or dead. What's your point?

SLS uses SSME's (actual flight hardware from STS), SRM's (more actual flight hardware from STS), modified STS ET's (obviously not the exact same hardware, but not entirely different, either), the tiles from the orbiter's TPS (with different shapes, obviously) and Avcoat (Apollo technology), upgraded crawlers, the VAB with upgrades to supposedly make it accommodate a variety of vehicles, and the same launch pads after major refurbishment. The orbiter is obviously a unique piece of hardware but it would appear that a lot of the key pieces of technology from STS are being used for Orion and SLS.

I guess everyone who was working on STS just kinda fell off the planet, but somehow the entire STS propulsion system, less OMS, wound up in SLS.

I told you why I wanted to use it.

- A real space exploration vehicle has to have a crew delivered to it and Orion is not a real space exploration vehicle, no matter how many times NASA repeats the lie.

- At $72M per copy the SSME is not what I would call cheap, so I would rather not throw four of them in the Indian ocean with every SLS flight.

- STS is the only vehicle that can de-orbit with a substantial payload and if the nozzle extensions are removed then the SSME's fit in the cargo bay and 4 of them are just below the weight limit for the orbiter to land with if the landing gear are upgraded.

Impaler wrote:

Shuttle was DANGEROUS, EXPENSIVE and INFREQUENT, the SLS/Orion while it is likely to be just as expensive and infrequent will at least be safer by virtue of being a capsule with launch abort systems.

How is it that Orion, using the same propulsion system with software upgrades, is far less dangerous? Because it has an unproven escape system strapped to it? An in-line launch configuration is preferable to side mount because it can't be struck by ET FOD, but SLS has not been proven to be safer than STS or any other launch system.

For around $18B, we're getting a tuna can with an escape rocket on top of it? Oh joy! Can we take a ride on that escape rocket right now so we have money for payloads that actually require SLS?

Imagine all the funding we could have for worthy SLS payloads like an orbital manufacturing module for ISS or a real manned space exploration program. I guess new toys are more important than science or exploration.

kbd512 · 2015-01-16 02:51:00

RobertDyck wrote:

kbd512: When Shuttle was flying, I tried to tell a couple Shuttle engineers my idea to save cost. I noticed the windshield was hand ground every flight to remove micrometeoroid pitting. They didn't use power tools, it was hand ground. Very labour intensive. My idea was to replace the glass with ALON: Alumino-Oxy-Nitride. That's a transparent ceramic developed under contract for the US army in the 1980s for windows of tanks. It's designed to be bullet proof. Since it can withstand dramatic impacts, that should eliminate micrometeoroid pitting. Both engineers told me they had ideas to reduce labour and expense processing Shuttle. And both engineers told me corporate executives told them no; that their goal was to maximize cost to pay employee salaries and corporate profit. So people far more qualified than you or me came up with ideas, but were told to shut up.

I'm not qualified to tell a NASA engineer anything but even I, and apparently they as well, can see when something is obviously ridiculously wasteful and inefficient.

There was precious little about STS that was managed correctly. The only real "accident" that the STS program ever had was that it worked at all.

I want NASA to implement workable solutions so that there is sufficient funding for real science and exploration. Apparently that's crazy talk.

RobertDyck wrote:

The first link posted by SpaceNut provides numbers for energy needed to bring ET to orbit. The first post says 1,514 kg of additional OMS propellant, reducing payload by that mass. The second post calculated reduced payload by 5,280.5 kg. And both calculate based on low altitude science orbit, not ISS. And that's a standard ET, not one modified to be a station module.

Yeah, so orbiting the ET would require additional OMS propellant capacity that the system doesn't have since no effort was put into reusing every part of our reusable launch system. We can't design pressure fed LOX/LH2 thrusters to circularize the ET's orbit using residual propellant in the tank because there's not enough funding for that. Throwing away hundreds of millions of dollars of hardware on every SLS flight, no problemo. It's more desirable to throw away a $50M investment than it is to make ISS module shells or lander frames from it in orbit to gain experience with orbital manufacturing and assembly. That's real applied science that has a direct application for space industrial purposes and we can't have any of that.

RobertDyck · 2015-01-16 03:59:50

I was thinking. To restart the main engines, ET requires acceleration to push LH2/LOX propellant to the siphon. So rather than use OMS entirely, just use OMS to gain sufficient acceleration to push ET propellant to the siphons. Then restart SSME. And SSME was started by a silane igniter on the launch pad. However, that web page mentions "direct insertion". NASA's website for the Shuttle states...

Following MECO, the orbiter's altitude and velocity will vary depending on the mission requirements. For example, an 80-nautical-mile (92-statute-mile) altitude with an inertial velocity of approximately 25,660 feet per second would place the orbiter in a suborbital trajectory so that the ET would enter following separation. In order to boost the orbiter to a viable orbit that does not degrade appreciably during the mission and satisfies mission objectives, two propulsive thrusting periods are made with the OMS engines, except in the case of a direct insertion, when only one OMS thrusting period is required to circularize the orbit. The first thrusting period is referred to as OMS-1 and boosts the orbiter to the desired apogee; the second burn is called OMS-2 and typically circularizes the orbit.

So direct insertion is preferable. That eliminates OMS-1, instead using the higher Isp main engines. Could the siphons be improved so there is less residual propellant? The quoted section in SpaceNut's post says 1,000 kg of LH2 and 6,000 kg of LOX left, or about 1% of liftoff propellant. Could that be used? Interesting. However, that again would lift an unmodified tank.

GW Johnson · 2015-01-16 11:26:57

Two cent's worth/first cent: I think the upshot of the postings about using propellant tanks of any kind as human habitation space, shows that flying it as a tank and modifying it in space has very serious penalties associated with complexity, weight, and safety. Modifying it on the ground to habitat configuration and then launching it dry to space as dead-head payload will work, and is what we did on Skylab. I'd hazard the guess that a purpose-built habitat riding as payload will be the better option, since there is no longer a surplus of Saturn S-IVB stages laying around unused. Pulling stuff out of museums is not a solution at all. The Bigelow inflatable approach has an awful lot of promise.

Second cent: when judging the wisdom (or lack) of what NASA did or does, you have to remember both (1) that and (2) why the NASA of post-1972 is not the NASA of 1958. Early on, a small organization heavy on engineers was tasked to do things fast, sparing no expense, but was not told how to do them. That actually worked quite well. NASA was the manned space program, with science and aeronautics sort of in the background. Plus there were dozens and dozens of contractors to choose from in letting contracts.

After 1972, the President and then Congress started telling them how and what to do in great detail, which micromanagement inherently strains budgets that have become the deciding factor in most decisions. The same micromanagement allowed the start of "consolidation" of all those contractors toward a monopoly. Budget pressure led to the side-mounted cluster of a shuttle that eventually killed two crews, and cost around $1B per launch to put at most 15 tons in LEO for ISS.

Today, NASA is a gigantic organization, filled with inertia, and totally micromanaged by Congress in terms of projects and money. It lets contracts mostly to the ULA monopoly (which Spacex is attempting to break). Only the big projects that Congress mandates get big budgets, there are other groups within NASA doing good things, just on a shoestring. The planetary science guys are sort of in the middle of that spectrum, but being neglected, are more successful because of less congressional micromanagement.

Overall, the organization has been trying to be "everything to everybody", for the last couple of decades at least. That never works out well. Without change, the dinosaur will very slowly die. That change has mainly to do with micromanagement coming from Congress instead of a real human mission to be done.

GW

Last edited by GW Johnson (2015-01-16 11:37:26)

GW Johnson · 2015-01-16 11:45:42

Third cent: propellant ullage. Why use a big motor like OMS to do a small motor's job? All you need is a very few hundred pounds of thrust acting on something the size of a Saturn S-II second stage. They did it back then with small solid propellant cartridge motors shaped like a thick pancake, about 5 inches in diameter, and about an inch and a half thick. There were 3 for redundancy. I crudely estimate 300 lb thrust each. Today you would do the same job with a few very small hydrazine thrusters, if you wanted something reusable. If it's one-shot, use the solid, it's cheaper and stores "carefree".

GW

kbd512 · 2015-01-16 12:34:36

RobertDyck wrote:

I was thinking. To restart the main engines, ET requires acceleration to push LH2/LOX propellant to the siphon. So rather than use OMS entirely, just use OMS to gain sufficient acceleration to push ET propellant to the siphons. Then restart SSME. And SSME was started by a silane igniter on the launch pad. However, that web page mentions "direct insertion".

Robert, you're still thinking like a NASA contractor. If there's 1% of the propellant left after STS or SLS attains 99%+ of orbital velocity, then the solution is pretty simple. The ET needs one or more small LOX/LH2 thrusters to circularize its orbit. It doesn't weigh nearly as much as the orbiter. I don't want to redesign the ET to make it a space station habitat, redesign the SSME to light off in space, or redesign the orbiter's OMS to feed from tankage in the cargo bay. All of those solutions unnecessarily complicate the design of the orbiter's OMS and SSME.

A simple pressure fed LOX/LH2 thruster to circularize the ET orbit after it's jettisoned from the orbiter is all we need. The only questions are as follows:

How much would the thrusters weigh?

Would the addition of the thruster interfere with any other aspects of the operation of the ET?

What is the optimal placement on the ET to minimize weight and complexity?

How difficult is it to pressurize the propellant tanks sufficiently to utilize the remaining propellant for use by a rocket engine that's much smaller than SSME?

How inexpensively can the system be made, accepting that it will be a single use computer controlled rocket engine that should not require a massive logistics tail to support it and need not be insanely over-engineered for the task of placing a gas can into orbit?

RobertDyck wrote:

So direct insertion is preferable. That eliminates OMS-1, instead using the higher Isp main engines. Could the siphons be improved so there is less residual propellant? The quoted section in SpaceNut's post says 1,000 kg of LH2 and 6,000 kg of LOX left, or about 1% of liftoff propellant. Could that be used? Interesting. However, that again would lift an unmodified tank.

If we just jettison the tank as we would in normal operations and use a thruster to burn the remaining propellant, then we don't have to concern ourselves with how OMS-1 would be affected, use of specific flight profiles, improved siphons, or redesign of the SSME or OMS.

From my rough estimates, over the life of the STS program more than seven million pounds of high grade aluminum alloys were thrown away after just 8.5 minutes of use. How many space station modules or lander frames could have been built with that much material if we had an orbital manufacturing facility to repurpose these materials?

Instead of trying to concoct ways to make the orbiter or other spacecraft capable of carrying a little more payload, if everything we send upstairs is added to a stockpile of raw materials for other uses, then pretty soon all you have to provide are warm bodies.

kbd512 · 2015-01-16 12:54:17

GW Johnson wrote:

Third cent: propellant ullage. Why use a big motor like OMS to do a small motor's job? All you need is a very few hundred pounds of thrust acting on something the size of a Saturn S-II second stage. They did it back then with small solid propellant cartridge motors shaped like a thick pancake, about 5 inches in diameter, and about an inch and a half thick. There were 3 for redundancy. I crudely estimate 300 lb thrust each. Today you would do the same job with a few very small hydrazine thrusters, if you wanted something reusable. If it's one-shot, use the solid, it's cheaper and stores "carefree".
GW

I think we have a winner.

If we did it the way you suggested, then we could haul them back to ISS with a solar electric tug, suck the propellants out and use them to provide oxygen and/or water for the crew, or simply use the propellants to keep our massive station in orbit. The SOFI could be used for, well, insulation.

RobertDyck · 2015-01-16 17:35:55

kbd512 wrote:

If we just jettison the tank as we would in normal operations and use a thruster to burn the remaining propellant, then we don't have to concern ourselves with how OMS-1 would be affected, use of specific flight profiles, improved siphons, or redesign of the SSME or OMS.

You have to ask why there is an OMS-1 burn at all. That is so Shuttle can jettison ET on a trajectory for safe disposal in the Indian Ocean. For normal operations you wouldn't stop the core stage there. Thrust to apogee makes sense. The Orbital Manoeuvre System should only be used for circularization. That means "direct ascent". So looking at the whole system, you wouldn't continue with a flight profile that is modified for ET disposal, then tack on an additional booster to prevent disposal.

You're looking at the material as raw resource. Bureaucratic management does not think that way. They see manufacturing as some mysterious black box. They can't conceive of repurposing equipment. They certainly can conceive of any sort of industrial work in zero-G. But there are also scientists. They find industrial work even harder to understand. They may be "technical", but I've attended conferences. Watch the TV show "Big Bang Theory", look at how the character Sheldon treats Howard. I've seen it; it happens. Any responsible use of resources is beyond their comprehension.

Another example: after Mars Polar Lander failed, the Mars 2001 Lander was postponed. It used the same chassis, so they wanted the problem solved before launching another potential failure. Good decision. However, once they found the problem, then didn't just fix it and launch. They lost interest and forgot about it. Then years later some scientists found it in storage, and decided to modify it for their needs. They removed all the engineering experiments, to make room for more fundamental science. They removed the radiation sensor, and the In-Situ Propellant Production Precursor. The repurposed lander became Mars Phoenix. A radiation sensor is on Curiosity, but we still don't have anything to demonstrate ISPP.

Use of resources generally sounds good. But you're going to require practical processes to use those materials before anyone lets you accumulate them.

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#1 2015-01-14 15:58:10

Shutte ET as ISS module

#2 2015-01-14 16:07:38

Re: Shutte ET as ISS module

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Re: Shutte ET as ISS module

#4 2015-01-14 16:18:24

Re: Shutte ET as ISS module

#5 2015-01-14 20:29:21

Re: Shutte ET as ISS module

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Re: Shutte ET as ISS module

#7 2015-01-15 03:21:10

Re: Shutte ET as ISS module

#8 2015-01-15 03:51:24

Re: Shutte ET as ISS module

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Re: Shutte ET as ISS module

#10 2015-01-15 14:32:55

Re: Shutte ET as ISS module

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Re: Shutte ET as ISS module

#12 2015-01-15 17:12:21

Re: Shutte ET as ISS module

#13 2015-01-15 19:53:25

Re: Shutte ET as ISS module

#14 2015-01-16 00:12:41

Re: Shutte ET as ISS module

#15 2015-01-16 00:46:21

Re: Shutte ET as ISS module

#16 2015-01-16 01:47:39

Re: Shutte ET as ISS module

#17 2015-01-16 02:13:06

Re: Shutte ET as ISS module

#18 2015-01-16 02:22:21

Re: Shutte ET as ISS module

#19 2015-01-16 02:51:00

Re: Shutte ET as ISS module

#20 2015-01-16 03:59:50

Re: Shutte ET as ISS module

#21 2015-01-16 11:26:57

Re: Shutte ET as ISS module

#22 2015-01-16 11:45:42

Re: Shutte ET as ISS module

#23 2015-01-16 12:34:36

Re: Shutte ET as ISS module

#24 2015-01-16 12:54:17

Re: Shutte ET as ISS module

#25 2015-01-16 17:35:55

Re: Shutte ET as ISS module

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