Space shuttle for space tourism and first stage TSTO.

[exoscientist]

This article describes the plan to sell the orbiters minus engines for $42 million:

For sale: Used space shuttles. Asking price: $42 million apiece
By John Matson
Dec 18, 2008 04:00 PM in Space
http://www.scientificamerican.com/blog/ ... 2008-12-18

It is currently intended only to be sold to educational institutions, or governmental agencies.
The Air Force is looking for designs for reusable first stage boosters for two-stage-to-orbit (TSTO) systems. Then it might be able to be used for this purpose. Most likely you would use kerosene fuel for this since dense fuels are more suitable for first stages.
The payload bay would be converted to a fuel tank, and the second stage of the TSTO would be carried on top or below the orbiter. High performance kerosene engines such as the Russian NK-33, with a near legendary thrust/weight ratio of 136.66 to 1 at a weight of 1,222 kg, could be used for propulsion:

NK-33.
http://www.astronautix.com/engines/nk33.htm

The orbiter without the SSME engines masses around 68,600 kg:

Atlantis.
http://www.astronautix.com/craft/atlantis.htm

Its payload bay is around 300 cubic meters that could be used for propellant. Using the densities of kerosene and lox given here:

Lox/Kerosene.
http://www.astronautix.com/props/loxosene.htm

and the oxidizer to fuel ratio of the NK-33 of 2.8 to 1 we can calculate the propellant load that can be carried as about 300,000 kg. You would need at least 3 of the NK-33's to lift this fuel load, orbiter and second stage.
The tank weight of kerosene/lox is typically around 1/100th of the propellant weight so around, 3,000 kg. Then the empty weight of the reconfigured orbiter would be 68,600kg + 3*1,222kg + 3,000kg = 75,266kg. And the fully fueled weight of this stage would be 375,266kg.
For this first stage alone without a second stage, this would be a mass ratio of about 5. Using an average Isp of the NK-33 of 315 you could get a delta-V of 315*9.8*ln(5) = 4,970 m/s, about Mach 15.
A total delta-V this high raises the possibility it could be used for suborbital space tourism or point-to-point hypersonic transport, if sale to commercial organizations were to be allowed.


Bob Clark

 

[Eman_3]

There are currently three operational Space Shuttles. They are due for retirement very soon, and once grounded (disregarding shuttle flights on the 747), will never fly again. Period.

 

[exoscientist]

The $42 million costs for the basic spacecraft is significantly less than the $150 million development cost of the Whiteknight2 and SpaceShipTwo:

Sales are rocketing at Virgin Galactic.
http://www.virgingalactic.org/2008/04/s ... rocke.html

and the result would be a vehicle that could do significantly more than the Virgin Galactic system. It could act as a suborbital space tourism vehicle, but it also could act as a very high speed point-to-point transport system. Imagine a cross-Atlantic trip instead of taking 6 hours only took 1/2 hour. Or a cross country trip instead of taking 5 hours only took 20 minutes.
Moreover, it could also serve as the reusable first stage of a TSTO. I'm arguing it could be used to reduce the costs to space if used as a reusable first stage booster for a TSTO system. The Air Force for instance believes such a TSTO could cut launch costs by 50%.
The Russian engines that would need to be added would be relatively low cost. According to this page, in the mid 90's Aerojet purchased 36 of them from the Russians for only $1.1 million each(!):

NK-33.
http://en.wikipedia.org/wiki/NK-33#History

Installation of the lox/kerosene tanks and modifications to strengthen the body frame to carry the extra loads would also be relatively low cost.
The 68,600 kg empty weight of the orbiter sans engines could probably be reduced also. The main system that could probably be removed would be the Orbital Maneuvering System (OMS). This is used for final orbital insertion of the shuttle and changes of its orbit. This wouldn't be needed for a first stage vehicle or a suborbital vehicle.
I don't trust the value given for the OMS weight however on the Atlantis Astronautix page. It says this:

Main Engine: OME. Main Engine: 14,912 kg (32,875 lb). Main Engine Thrust: 53.367 kN (11,997 lbf). Main Engine Propellants: N2O4/MMH. Main Engine Propellants: 12,412 kg (27,363 lb). Main Engine Isp: 316 sec. Spacecraft delta v: 700 m/s (2,290 ft/sec).

The OME refers to the OMS engine. The engine does not weigh 14,912 kg. Perhaps they are referring to the entire OMS system, both pods. That seems unlikely as well, unless they are including the propellant weight.
In any case it's this OMS system weight that I'm trying to find out to subtract off.


Bob Clark

 

[Astro_Robert]

Nobody is seriously considering using the shuttle as a re-usable flyback booster for a TSTO, there are simply too many massive drawbacks.

#1: Cost: It costs approximately $1B for each Space Shuttle flgiht. Even if you transported 10 people in a second stage vehicle, that is still $100M each, just for low orbit, the Russians do it for $20M already. The reasons it costs that much have to do with the design of the system, requiring solids and other rather extensive infrastructure and servicing between flights. The Air Force does not have $1B per flight, when even EELV costs only about $100M and 'man-raing' EELV would be cheaper than continuing Shuttle.

#2: Age: Everyone claimed the Orbiters were designed for 100 flights (a nice round number that sounds good). However, most of the fleet has about 30 flights each and they are all showing serious signs of age, and require lots of maintenance between flights. Using such a beat up vehiclefor a new program would be seriously unwise.

#3 Performance: The engine numbers you are using are OMS - Orbital Manuevering Systems engines only. These are the small engines at the corners of the Shuttle's rear end. They are not involved in any way during launch, they are only used to manuever in orbit and to de-orbit the Shuttle-Orbiter. Dry mass is nice, but when launching you have to take into account fuel mass as well. Shuttle cannot launch without the solids and does not have the performance to be used for any other purpose without spending so much money you might as well start from scratch. Note the Space Shuttle Main Engines (SSME) put out about 475,000 pounds of thrust each (they have recieved upgrade, but that is a reasonable ballpark). Even at 1.3+ Million pounds of thrust the 70,000 pound orbiter plus fuel in the ET is just too damn heavy, which is why solids are required. Even forgoing the ET by putting fuel in the cargo bay is probably not going to get you the performance you need, assuming you could solve problems #1 & #2.

At the end of the day, the Shuttle program has been a nice lesson in re-usble vehicles, and in what sorts of capability we desire/need in space but its time is over. Trust me, if using Shuttle for this purpose was a slam dunk, there are lots of would be space entreprenuers who would throw money at it. The shuttle is done.

 

[exoscientist]

Nobody is seriously considering using the shuttle as a re-usable flyback booster for a TSTO, there are simply too many massive drawbacks.

#1: Cost: It costs approximately $1B for each Space Shuttle flgiht. Even if you transported 10 people in a second stage vehicle, that is still $100M each, just for low orbit, the Russians do it for $20M already. The reasons it costs that much have to do with the design of the system, requiring solids and other rather extensive infrastructure and servicing between flights. The Air Force does not have $1B per flight, when even EELV costs only about $100M and 'man-raing' EELV would be cheaper than continuing Shuttle.

The point is it wouldn't be expensive to use without the massively expensive (and expendable)external tank, the solid rocket boosters, and the SSME's, the most expensive and labor intensive rocket engines ever made.
For a first stage use where you have a heavy upper stage, the delta-V that the orbiter would reach would be significantly reduced, say, to about 2,000 m/s. You could use much simpler, lighter, and nearly maintenance-free thermal protection systems as well, so those costs would also be drastically cut.


Bob Clark

 

[moonfie]

I think that for safety reasons more than cost reasons the space shuttles probably won't fly again once retired. The ships are coming up on 30 years old (except for Endeavour), and regardless of whether or not they're actually safer, would-be space tourists would probably be more likely to hedge their bets with new technology like SS2 or even Dragonlab, rather than the sisters of Challenger and Columbia.

Not to say that cost isn't a big issue. Especially since whoever buys the shuttles will find it challenging, once the shuttle is retired, to keep getting new external tanks at a reasonable cost.

That said, I've wanted my own space shuttle since I was about 12. Anyone have $42 million I can borrow? :lol:

 

[Astro_Robert]

You cannot use the OMS engines for launch, they are simply too weak.

If empty weight of Orbiter is ~70,000 pounds then fueled weight is probably on the order of 700,000 pounds (payload fraction is typically less than 10%), assuming you could fit that much fuel into the cargo bay. With OMS engines putting out 12,000 pounds of thrust each, this would then take 60 engines, which is completely nuts. Even the Russians have never attempted such a complicated plumbing scheme, and Western rockets almost never go for more than 5 engines per stage.

Yes, the SSME are horribly expensive, but if it were possible to design a worthwhile launcher with OMS engines, someone would have made a disposable one already. For large launchers, people use large engines because each engine involves a weight penalty to add (structure, gimballing, plumbing for fuel etc..) However, designing large engines is also horribly expensive so they settle on 3-5 moderately large engines per stage. Someone might be able to build a sounding rocket with OMS engines, but that is a far cry from a TSTO.

 

[exoscientist]

You cannot use the OMS engines for launch, they are simply too weak.

If empty weight of Orbiter is ~70,000 pounds then fueled weight is probably on the order of 700,000 pounds (payload fraction is typically less than 10%), assuming you could fit that much fuel into the cargo bay. With OMS engines putting out 12,000 pounds of thrust each, this would then take 60 engines, which is completely nuts. Even the Russians have never attempted such a complicated plumbing scheme, and Western rockets almost never go for more than 5 engines per stage.
Yes, the SSME are horribly expensive, but if it were possible to design a worthwhile launcher with OMS engines, someone would have made a disposable one already. For large launchers, people use large engines because each engine involves a weight penalty to add (structure, gimballing, plumbing for fuel etc..) However, designing large engines is also horribly expensive so they settle on 3-5 moderately large engines per stage. Someone might be able to build a sounding rocket with OMS engines, but that is a far cry from a TSTO.

I wasn't thinking of using the OMS engines. I wanted the weight of the OMS pods to subtract off their weight from the dry weight estimates of the orbiter because I wanted to remove them since they wouldn't be needed for suborbital or first stage only use.
If anyone knows a reliable source for the weights of the obiter's various components I would like a ref for that.


Bob Clark

 

[exoscientist]

On another forum someone reminded me, you could just use wet wings as the propellant tanks. As a preliminary estimate, the wing volume may be close to that of the payload bay based on a wing area of 250 square meters and a maximum wing thickness of 1.5 meters. Then you could keep the large shuttle payload bay to carry payloads while having close to the same propellant load. You would need some strengthening of the wings though, which would increase the dry weight.


Bob Clark

 

[exoscientist]

Using wet wings only as the propellant tanks would solve the problem of a cryogenic-fueled upper stage's flaking insulation damaging the wings of the orbiter. It would also allow quite large payloads, at least in volume.
If used for space tourism, the payload bay could then carry many passengers now, much more than what I had been envisioning as only 6 or so in the shuttle crew compartment. Quite a bit more also than the 6 passengers of SpaceShipTwo. With the 60 ft by 15 ft payload bay, say you allowed a 3 ft by 3 ft space per passenger. You could carry 100 passengers(!) You could then charge a much lower price per passenger, and still make a profit.
With this many passengers, the vehicle would be much more like an airliner now, and the hypersonic transport market now becomes potentially much more lucrative.
And this for an initial investment of $42 million.


Bob Clark

 

[vattas]

Installation of the lox/kerosene tanks and modifications to strengthen the body frame to carry the extra loads would also be relatively low cost.

Do you really think so? I think that it would mean complete rebuild of the shuttle - frame, wiring, etc.
In most cases it's far cheaper to design and build something from the scratch than to adapt something that was build with completely different goals in mind...
So this idea is ridiculous...

 

[exoscientist]

Installation of the lox/kerosene tanks and modifications to strengthen the body frame to carry the extra loads would also be relatively low cost.

Do you really think so? I think that it would mean complete rebuild of the shuttle - frame, wiring, etc.
In most cases it's far cheaper to design and build something from the scratch than to adapt something that was build with completely different goals in mind...
So this idea is ridiculous...

The last shuttle built cost in the range of $2 billion. Undoubtedly a large part of that were the quite expensive SSME's. I'm suggesting much cheaper Russian engines be used instead. The cost to add strengthening members to the payload bay or the wings would not cost $100 million which is approaching the cost of an entire airliner which has strengthened wings to hold fuel. So the cost would still be less than the the cost of the Virgin Galactic system while being able to do much more and being able to carry many more passenegers if used for transport or tourism purposes.

Bob Clark

 

[Astro_Robert]

Putting jet fuel in wings is one thing, putting cryogenic and/or hypergolic rocket fuels in them is another. Even if you were to convert to Kerosene-LOX it would still cause a problem. For airplanes wet wings requie only modest plumbing and structural modifications to carry and distribute the jet fuel as needed. For Shuttle, storing cryogenic LOX in the wings would be a prohibitive problem by itself, not to mention plumbing and other modifications necessary to supply the vastly higher fuel flow rates to the rocket turbopump. Even with the ceramic tiles covering them, the wing internal temperature is probably not suitable for kerosene, and definitely not suitable for LOX. Rocket fuel tanks are also higher pressure vessels than aircraft tanks (again turbopump fuel rate requirements), and this would be difficult to implemtent in a wing area.

Also, I don't think the wing internal volume is nearly as much as you are trying to give them credit for. The external thickness may be close to 1.5 meters at points, but the shuttle tile stack has ~5" thickness on both sides of the wing, which is more triangular than square.

I believe the actual cost of the orbiters is coser to $3B-$4B each, and if they could soup up the performance so easily for just a $100M-$200M dollar modification they would have done so a very long time ago. The Shuttle is a dog of a compromise to allow re-usability and direct access of Astronauts to their cargo. We learned a lot from it and it served well for as long as it could, but it is time for it to be retired.

 

[vattas]

It doesn't matter if you use cheaper engines or not. Modification of airframe/plumbing/wiring to hold propellant tanks in payload bay alone would cost more than 40 mil $. Not to mention modifications required to accommodate new engines.
"Take something and modify it to serve different purpose" sounds cheap only on paper.

 

[ZenDraken]

This is an interesting intellectual exercise, but there's no way it would be economical, practical, or safe. Much better and frankly easier to start from scratch, and fly a new airframe.

I'd think a 747-class suborbital "White Knight 3" with an orbital "Space Ship 3" as a second stage would be cheaper, easier, and safer than trying to salvage a shuttle airframe.

 

[AdmiralQuality]

Bob Clark, your post is completely moronic. Is it meant as an intentional troll? This sounds like something a six year old would suggest. "It's shaped like a space ship and already has pilots seats, lotsa knobs and switches, and a joystick thingee, why don't we just stick some rockets in the back and fill the wings and payload bay with fuel and fly it to Japan?"

Stuff isn't made out of Lego. A space shuttle is BARELY useful for what it was *designed for*, and is *completely* useless for any other purpose, except of course museum piece. If they were as viable machines as you seem to think, they wouldn't be retiring them.

 

[najab]

It ain't gonna happen. Building rockets is a lot more complex than simply bolting some engines onto the back of something and pointing it at the sky. Though, saying that, given the number of changes you are proposing it might make more sense to start with a DC-9 than an orbiter.

 

[Geoduck2]

An interesting idea but unfeasible.
It would be equivalent to trying to retrofit a Stanley Steamer with a Prius drivetrain
To outfit a Scottish Castle with electrical and ethernet.


Not to say it wouldn't be possible. Lots of things are possible. It just wouldn't be cost effective and the result would be a kludge that wouldn't work as well as something designed from the ground up with modern systems.

 

[brandbll]

None of this makes any sense. If the fleet wasn't aging and their was a more cost effective way to using the fleet, why would NASA be retiring the shuttle in the first place? Why wouldn't NASA be doing all those things stated in the OP if they were that simple? How the heck did this thread make it to the front page?

 

[AdmiralQuality]

I agree brandbll, featuring an idiotic suggestion like this on the site's front page is a new lowpoint of journalism here at Space.com.

 

[echoesofapllodotcom]

I agree that the air (or space) frame is too old for cheap operation. It can be kept going, but the cost / benefit curve starts to go "south" real fast and when these airframes get to 50 years old?

With 2 million separate parts it is almost impossible to service them as no one makes them anymore as they stopped making them 25 years ago!

Computer parts would be impossible to replace and the revamped software alone would be a nightmare for the new launch system and engines.

I am also betting that the cost of inspections of the tiles and replacement systems would be a deal breaker all by themselves. Time in space doing inspections (one day) and the standby shuttle to do a rescue in case of tile damage - sure the chances are reduced with a diffeent launch system, but you don't know what you don't know until it is too late. The loss of 2 other shuttles and crew are an unfortunate testimony to that.

When it comes to aeroplanes I don't like flying in things that are 30 years old let alone going into space in an aging shuttle.

as for reentry and getting places, it is a simple matter of costs again. It takes the shuttle (because of the vast number of systems and inspections) 2 days to get to the ISS and another three days to get back. It takes Soyez very much less to get there and 3 hours to get home.

Hey, lets not forget about keeping aging 747s on stanby for bringing the craft home if it lands in another part of the country or the world due to storms in the US.

Have you thought about how the transport system (2 x 747s) will work if they have to carry the extra weight of tanks. The system was designed for the current weight of an empty shuttle and the 747s are working overtime to keep in the air - they only travel in 1,000 mile hops with the fuel consumption.

Astronaut training and simulators will be far more complex than say Soyez or modern vehicles. When I was involved in the support of STS1 the flight manual was pretty thick and now it is immense with so much more to handle.

The barriers are immense and although people hate retiring the shuttle, as was pointed out earlier, there are many, many, very, very good reasons. If the government grounds these vehicles for any reason, the cost to get the three of them airworthy again will be immense and back breaking let alone bank breaking. Have a look at current tourist costs to space (sure they have pretty much suspended these trips, but US$20M per ticket and for NASA US$50 per ticket - nice price hike).

Do you know how many people it takes to change an ISS light bulb with a new shuttle crew - Tens of thousands. Sure take away the external tanks and boosters and even cut the team in half, but do you know what you will be competing with? Teams of less than 100 for the new tourist systems coming on line with new low cost vehicles with fewer working parts and newer electronics systems and lower power consumption. Did I mention that smaller ships will be easier and cheaper to launch with less fuel?

This should not have been a front page article, but the world is short of space news for the past couple of weeks! For a bit more information on Soyez vs Shuttle (launch and landing) http://echoesofapollo.com/2009/12/31/readers-questions/

Robert Brand
Global Events Manager
Echoes of Apollo

 

[MeteorWayne]

I often shake my head at the articles they decide to link to. Like this one. The plain and simple fact is, the Shuttle program is in lame duck status. There are 5 missions left, and after that, the fleet will be retired. NOTHING, not even neat ideas, pipe dreams, pie in the sky suggestions, Armegedon, or flying monkeys is going to change that one bit. Why continue to beat a dead horse again and again. There are a hlaf dozen threads here that all say the same thing...repeatedly. There are no more ET's, there's no one to maintain the vehicles after the current missions, there's no money coming from anywhere to suppport it. The program is finished, finito, over with, done.

It makes the moderator's job much harder...I wish they'd pick better topics myself.

MMW

 

[blackarrowwillliveagain]

Yes, an idiotic suggestion. Okay, you buy an orbiter for $42 million - less engines. Well, it costs NASA with all its existing infrastructure about $1 BILLION per mission. Cloud cuckoo land, why does Space.com entertain idiotic ideas like this?

 

[GreenDude]

Astro Robert. Some of your facts are wrong.

A shuttle launch is about a 700 million dollar cost. I have seen several people refer to the 1B cost. That is incorrect.

The shuttles WERE designed for 100 flights. The orbiters themselves are not wearing badly, it is the infrastructre that supports them that is at issue. The manufactures of the on-board propellant tanks are either no longer around or no longer tooled to support the project. Many other parts are either hard to find or no longer produced. The regular maintenance items have been an issue because of disarray in the program. The orbiters are still in good condition. That is a testament the the people that work on them and prepare them for flight.

The shuttle uses the OMS engines late in the ascent for an extra bit of kick. If you listen to a launch and the commentary, they always refer to when the OMS engines are burning. They didn't used to until having to launch to the orbital inclination the ISS is at. That inclination was dictated by the Russians. That inclination also lowered the shuttles weight capabilities.

The main engines produce about 432,000 lbs thrust. At full thrust, they produce 110 % of rated performance. The orbiter weighs in at approximately 100 tons, not 70,000 lbs. If you listen to the launches and landings, they always talk about the "100 ton" vehicle/glider.

I agree with Eman 3. The orbiters have done their job. They will be retired and will only fly again in films. They were a project that was ahead of it's time without the technology to really support the vision.

 

[jerrycobbs]

Even assuming that it's physically possible to make the necessary modifications for this (and if you're going to assume something that off-the-wall why not just "assume" yourself a warp drive and let's go to Alpha Centauri while we're traveling), one of the first things done after the Challenger accident was to cancel the Centaur liquid-fueled upper stages that the shuttle used to carry in the payload bay. The shuttle's design is marginal enough, safety-wise, without stuffing the payload bay full of propellant again. I'm all for speculation and thinking outside the box, but this whole thread sounds like the people who want to strap a rocket to the ISS with some duct tape and head off to Mars. Stuff like this reaffirms my concerns about the state of math & science education in this country.