O-kay, wacko space technical question time! (It’s been awhile—I was getting out of practice.)
Here’s the setup: I’m going to launch a space shuttle mission, but instead of using the Space Shuttle Main Engines/External Tank and the Solid Rocket Boosters, I’m miracleing the spacecraft up from the launch site on it’s ascent profile (hell, say Superman pushes it. Whatever). The orbiter is otherwise unmodified*, and still uses the OMS engines for orbital injection and deorbiting.
Now, how much does this change the cost of an average mission (say, circa 2002)? I’m assuming it isn’t as simple as just deleting the cost of the ET and SRBs from the total—I imagine every change would effect things up and down the line of a mission elements, and these are pretty big changes. It also isn’t as simple as “the prepared orbiter magically appears in orbit.”
There—I think that was halfway intelligently written enough to be answerable, though I’m far from sure. Can anyone weigh in?
*Which is, admittedly, an iffy proposition in itself. I don’t even know if the landing gear can be retracted under the vehicles own power.
I’m having trouble parsing this part of your sentence.
Do you intend that the shuttle take off from a runway? Without either solid rocket boosters OR an external fuel tank? I was under the impression that the external tank supplied all the fuel for the main engines; without that, the craft is just a glider with engines.
The marginal cost of the SRBs and the use of the SSMEs is only a small percentage of the total costs. If you otherwise have a normal Space Shuttle mission profile you’re paying to keep the NASA/ Mission Control infrastructure in existence. It pretty much costs about five billion a year just to have the option of conducting Shuttle missions.
While that may be the case, the ability to magically (and safely) propel the shuttle into orbit would change the costs enormously. You wouldn’t need to design your orbiter to sit on top of 4 million pounds of propellant. You wouldn’t need a launch area the size of a small city. You also wouldn’t need to make countless weight concessions.
I’d say that launching into orbit is an order of magnitude harder than re-entry, which is an order of magnitude harder than working in the environment of space. Without the rocket, going up into space would be comparable to deep undersea exploration. Technologically advanced, but more like $4M per trip vs. $400M.
True, but a not insignificant part of that is maintaining the fueling and RSRM handling systems, and keeping people trained. If you eliminate all of the pressurized systems and cryogenic storage/production, massive solid propellant motors and the associated explosive hazard provisions, along with all of the support and monitoring that goes with it, you can essentially launch off of a bare pad with a minimal provisions (umbilical connections, payload handling and conditioning, crew provisions). You still have between flight refurbishment and expendable item costs as well as the planning, risk mitigation, and mission assurance activities, but the on-orbit support costs are almost marginal, e.g. the people doing the operations would just be doing other support work or training anyway. For launch you have the range support costs, but once it is in orbit all of the normal mission flow is essentially health and status monitoring and mission direction. Since the main boost propulsion system is also the item that the failure of which is most likely to cause catastrophic loss of mission (versus any kind of structural, electrical, or software failure of the Orbiter Vehicle) you also eliminate essentially most of the risk assessment and mitigation efforts. I doubt the cost would be $4M per mission, but it would certainly be cheaper than the current half-billion dollars per launch of direct support, and far less than the facility and work force sustainment costs of the STS.
This scenario of the OP is, of course, all fantasy. Even the simplest of realistic systems using LOX/RP1 propellants require substantial launch facility support and the attendant hazards of cryogenic oxidizer and pressurized systems, and require substantial acceptance testing, monitoring, and day-of-launch simulation to assure that flight loads will not exceed the design margins of the booster system. There are ways of reducing the relatively fixed facility costs (see the Truax “Sea Dragon” concept) and trading per-mass performance for robustness and reliability, but the bulk of the cost of a launch using chemical propulsion systems is not in the fabrication of the vehicle or booster systems themselves, but in the logistical support and verifying the integrity of the system.
Oh, and tell Superman that he needs make sure to roll the Orbiter belly up and throttle down just before Qmax*alpha so that the wings don’t break off.
Heh—funny story,* I actually discovered that first hand in a flight simulator, testing out a space shuttle build. It wasn’t even a spaceflight-specific simulator, just one robust enough that spaceflight was possible. And throttling back at the appropriate time, as in real life, solved the problem!
Kinda like my first flight in an F-22 on the same sim—I crashed horribly, but I crashed almost identically to how an early F-22 crashed in real life, in the same conditions. Accurately simulated failure is a thing of beauty.
And thank you for the input, all!
*My definition of “funny story,” admittedly, probably being somewhat different from the average person’s.
