…if you didn’t care how long it took, and air and food for the crew were of no concern, that is? (Let’s say either the crew has died, or a robotic shuttle is being sent). If the answer is “no” to any of these three possible destinations, would it make a difference if the cargo compartment were converted to fuel tankage?
I don’t think there’s enough energy in the various engines used to loft the STS into orbit to get it anywhere near Lunar orbit. That’s why the Apollo missions relied on the MUCH larger Saturn V rockets to get them there. Remember that the Earth’s gravitational pull is still significant at Shuttle orbit altitudes–the astronauts don’t experience it because they are in a perpetual state of freefall. It takes energy to climb out of a gravity well, and the deeper out you want to climb, the more energy it takes. In practice, the ship would only have to go as far as the point where the strength of Earth’s gravitational field gives way to that of the Moon’s gravity. However, that point is still much closer to the Moon than it is to Earth; still too far for the little Shuttle. Even if you converted the payload bay to fuel storage, I don’t think that would be enough.
I’m shooting from the hip here and basing my replies on what I recall reading about the shuttle from well over a decade ago, so take this with a grain of salt.
But I believe the answer is no to all your questions.
That’s because I believe the shuttle is dependent upon its launch rockets for any real significant ability to achieve its altitude. The thrusters on the shuttle itself I recall being there just for minor maneuvers and altitude changes. So adding fuel to the shuttle itself wouldn’t change this much.
Now maybe a doper with significantly more knowledge about the shuttle will come along.
This paper (warning: PDF) on the feasibility of using the Shuttle Orbiter for cislunar flight may be of interest to you. Note the conclusion on the final page (Report Documentation Page):
The reasons for this (some stated, others implied, in the report) are:[ul][li]The Orbiter was never designed to make more than LEO, and doesn’t contain fuel storage or propulsive capability for TLI (trans-lunar injection).[/li][li]While the SSMEs (Space Shuttle Main Engine) are nominally restartable and have been restarted on the test stand, they’ve never been designed or tested to do so in operational configuration.[/li][li]The OMS (orbital maneuvering system), which is restartable, is only designed for LEO (low earth orbit) injection, circularization, and return, and has insufficient impulse to effectively execute a TLI.[/li][li]The Orbiter carries a significant amount of parasitic mass in the form of wings and lifting body that is of no use for cislunar flight.[/li][li]The Orbiter guidence and communication systems are designed only for orbital flight. Redesign would be significant.[/li][li]Original orbital mission profiles were insufficient in length for cislunar transit, though extended missions have occured later in the STS program.[/li][li]Not sure what you’d do with the Shuttle when you got there; the Orbiter can’t land on the Moon’s surface, of course, and any lunar lander would have to be constrained to fit within the Orbiter’s payload bay; not impossible, but limiting to be certain.[/li][li]Perhaps most significantly, the Orbiter TPS (thermal protection system–the carbon-carbon nose and wing edges, and the thermal tiles) cannot withstand a direct re-entry from transEarth return trajectory; you’d have to carry additional fuel to slow/circularize the Orbiter’s path to something it could withstand. [/ul][/li]
Obviously, some thought has been put into this, but given the current system it’s not practical. During the mid-Eighties through early-Nineties I believe NASA Glenn Research Center worked on some conceptual designs for a nuclear propulsion-based replacement for one or more SSMEs (in combination with a redesigned liquid booster system) to give it greater altitude but this came to naught for political, fiscal, and technical reasons. Whether these could have provided sufficient impulse to achive a cislunar transit is unknown (by me, anyway) but it seems likely that if developed it could have been a possibility, again limited by the above concerns.
As far as Mars, Pluto, et cetera…not a chance. I mean, you might be able to strap on some boosters and sling it out there unpowered, but it simply isn’t designed to operate for the length of time required for such transits; you’d be sans power, sans enviro, sans control long before you got to any other planets.
Following Tapioca’s Wikipedia link leads us to this discussion page. Scroll down to the “Lunar Shuttle” title, where you will find this:
I don’t see why a modular propulsion system couldn’t be devised that could be delivered to the ISS and would attach to STS upon the orbital arrival/inspection phase.
STS carries some crap to the Space Station, gets fitted with a modular nucular-ionical pack, picks up payloads delivered by Soyuz or modified Vostoks, and then blasts off with the cargo on a round-trip to Moonbase Omicron. You know, like a shuttle?
If not, isn’t this what we should be designing?
'Cause the Shuttle Orbiter’s design is not “modular” or designed to accept external propulsion systems, save for the SRBs. The cost of modifying a Shuttle to interface with an external propulsion system (combined with the system itself) would be money–an extraordinary amount–down the hole.
Care to go into more detail on this “modular nucular-ionical pack”?
It’s codenamed StarDrive and might be introduced before the current president is out of office, hence the “nucular.”
Then this thing sounds like a dead-end vehicle. It’s sad, but I think you’re right.
Turn it into a tourist trap.
Stranger, I’m going to pick this one apart, only to generate some discussion. I’m an EE by training, CE by trade, and have taken a class in “Rocket Science”, all of which send up some interesting flags in my mind. I’m purely being a Devil’s advocate.
*** While the SSMEs (Space Shuttle Main Engine) are nominally restartable and have been restarted on the test stand, they’ve never been designed or tested to do so in operational configuration.**
Aren’t the engines restarted in orbit? They fire 'em up for launch, and fire 'em for reentry. To my knowledge, they don’t keep 'em burning during the flight, so they’d have to be restartable. IIRC, they use them to make minor orbit corrections, so aren’t they restartable multiple times?
*** The OMS (orbital maneuvering system), which is restartable, is only designed for LEO (low earth orbit) injection, circularization, and return, and has insufficient impulse to effectively execute a TLI.**
This one you raise a good point. However, I would take an upgrade of the software and hardware (both on-flight computers and booster rockets) to be a less costly endeavor than to design a completely new vehicle. Point taken, though.
*** The Orbiter carries a significant amount of parasitic mass in the form of wings and lifting body that is of no use for cislunar flight.**
I can only see a problem with this if drag was involved, and in translunar flight in a vacuum, drag would be minimal at best. If anything, it would require a higher impulse engine/more fuel to propel the extra mass (generating a higher inertia). If not, it’ll just take you an extra day to get there, but who cares? You’re in the damn Shuttle, the “Cadillac of the Stars!” (a helluva lot more comfortable than the Apollo Command and Lunar modules). Engineers on the ground can preprogram the software with the givens, and calculate the flight paths accordingly. Again, they’d probably have to upgrade the reaction thrusters and main engines, but I don’t see this as something completely undoable.
*The Orbiter guidence and communication systems are designed only for orbital flight. Redesign would be significant.
Feh! Slap an amp on it, and you’re fine! Again, it’d be some swapout of hardware and a little rewiring. Assuming NASA would keep it’s commo frequencies the same, it may just be as easy slapping an amp and new antenna on the thing–but I don’t know their specs, so I can’t say. But I can imagine it’d be a helluva lot easier than changing out the engines.
*** Original orbital mission profiles were insufficient in length for cislunar transit, though extended missions have occured later in the STS program.**
IIRC, the Apollo missions were 6 days long. Weren’t the longest Shuttle missions on the order of 14 days or so? Even if your circumlunar time was two or three days, wouldn’t that be enough to at least get the program started to see how they could extend the flight time?
*** Not sure what you’d do with the Shuttle when you got there; the Orbiter can’t land on the Moon’s surface, of course, and any lunar lander would have to be constrained to fit within the Orbiter’s payload bay; not impossible, but limiting to be certain.**
Yeah, this is something we’d have to explore when we got there. I couldn’t even begin to speculate on what they’d be able to land on the surface, given the relatively cramped size of the cargo bay.
*** Perhaps most significantly, the Orbiter TPS (thermal protection system–the carbon-carbon nose and wing edges, and the thermal tiles) cannot withstand a direct re-entry from transEarth return trajectory; you’d have to carry additional fuel to slow/circularize the Orbiter’s path to something it could withstand. **
Something I would think they could achieve by a combination fuel/high orbit combination, whereas they use their Earth orbit to slow themselves down (higher eccentricity orbit). As far as the tiles themselves, hell, throw a tarp over it, and it’ll be fine.
Like I said, just some thoughts. After looking back at some of my thoughts though, it may be cheaper and more cost effective to just design a new vehicle for the purpose. But you know me: Slap the Shuttle on a Delta IV rocket and send 'er up!
I’m not a rocket scientist, but I play one on TV.
No. The engines used to decelerate the STS orbiter for reentry are small secondary engines located to the sides and somewhat forward of the main engines.
That parasitic mass has to be carried to the moon. More mass = a lot more energy (and therefore, bigger engines, longer burn time and a higher delta-V) required for a trans-lunar injection. The problem is a lot bigger than just “it’ll take more time.” Remember that more fuel also adds mass. The space shuttle is heavy. Building a whole new high-impulse engine to get that mass to the moon is an absurd proposition. As long as you’ve got to design an entirely new system (and you would), why try to keep an aging, inefficient design flying when you could design a new vehicle to do that job, and do it better?
I don’t want to be rude, but I strongly suspect that you have NO idea what you’re talking about here. The communications might not be a big problem, but guidance is a major issue. It’s a whole new ballgame to successfully navigate to the moon compared to LEO. We’re talking about entirely new software, new instruments… this is a big deal.
This makes sense, but it still invites the question “why bother?”
No. The engines used to decelerate the STS orbiter for reentry are small secondary engines located to the sides and somewhat forward of the main engines.**
I could have sworn they actually maneuvered the main engines directly into the flight path to provide the best impulse to slow them down. I didn’t think the maneuvering thrusters had the capacity to degrade the orbit to a reentry point. If not, I stand corrected.
That parasitic mass has to be carried to the moon. More mass = a lot more energy (and therefore, bigger engines, longer burn time and a higher delta-V) required for a trans-lunar injection. The problem is a lot bigger than just “it’ll take more time.” Remember that more fuel also adds mass. The space shuttle is heavy. Building a whole new high-impulse engine to get that mass to the moon is an absurd proposition. As long as you’ve got to design an entirely new system (and you would), why try to keep an aging, inefficient design flying when you could design a new vehicle to do that job, and do it better?**
And yes, you’re right: more mass = more fuel. However, the problem could still be solved. Doesn’t the Shuttle at one point actually generate less thrust than it’s mass, only to maintain inertia while burning weight to actually generate thrust again? I’d venture to say you could use the same idea here. Yeah, it would require a whole lot more fuel (causing my train of thought to derail at the station), but it might work.
I don’t want to be rude, but I strongly suspect that you have NO idea what you’re talking about here. The communications might not be a big problem, but guidance is a major issue. It’s a whole new ballgame to successfully navigate to the moon compared to LEO. We’re talking about entirely new software, new instruments… this is a big deal.**
I took the comment solely as a communcations question, completely forgetting about the navigational telemetry that has to go back and forth between the flight and ground. While you are correct in that I completely neglected the data portion of signals, again, wouldn’t it be a case of upgrading some software, throwing a higher power transmitter and directional antenna on the body? As far as I see with the transmissions, you’re only dealing with longer distances and the time delay associated with them. You’d need a better on-board processor and software to deal with the “gaps” in uplinks from Houston, and maybe a little more power to bounce voice signals onto ground tracking stations or the current DoD commo sats in orbit already. Either way, two questions not insurmountable on the ground.
This makes sense, but it still invites the question "why bother?"
Because I’m an engineer so, “Why not?!?”
Don’tcha love it when geeks get together?
Responding to your comments parenthetically:
Nope. The SSMEs (fueled by the External Tank, that big orange thing slung under the Orbiter) fire only during initial ascent. All orbital maneuvers and re-entry operations are done with the OMS and RCS thrusters. Also, note that the SSMEs are angled out (to compensate for the affect on mass center of the fuel in the ET); while the nozzles can articulate some, they’re not designed to be used sans tank.
I beg to differ; the cost of making significant mods on the Orbiter, owing to the complexity, poor engineering documentation, non-availability of parts, tooling, and indeed, original subsystem contractors, safety and traceability requirements, et cetera would probably be in excess of working from a clean-sheet design. Think of the cost of restoring a classic car to “like new” condition versus driving down to the dealership and buying a brand new car.
The issue isn’t drag–there is essentially none above LEO–but of mass. The more mass you haul, the more you fuel you have to carry (which is also mass) to start and stop it. The Shuttle Orbiter has a heckofalot of mass to fulfill it’s flydown and cross-range functions that is totally unnecessary for cislunar flight.
And I doubt you’re going to build a higher specific impulse chemical motor that will fit in the package of the SSME; it’s the highest power/weight engine ever build. While more powerful engines. The Rocketdyne/Boeing RS-68 (to be used on the CEV booster) is more powerful (and far less complex) but isn’t going to fit on the Shuttle frame.
Guess again. The Shuttle limped on for years using ferrite-core memory and what were essentially Apollo-type flight computers because of the reluctance of NASA to risk having to develop and debut new guidence hardware. This is a hell of a lot more complex than commercial electronics; four and five times redunancy, protection from EM effects, et cetera. Undoubtedly, you could design and install a communication system that would be adequate for cislunar distances, but the expense would be large; again, bad money after good.
3 out, 3 back, plus actual lunar orbit time. As you point out, though, the original mission duration of the Orbiter (7-8 days) has been long exceeded; with Extended Duration Orbiter modifications standard missions can be planned out to 15 days, with the longest operational mission time actually around 17 days, IIRC. So, that’s a nonissue.
A high eccentricity orbit is bad, bad, bad for the Shuttle. Apollo managed their Earth return via ballistic (i.e. direct injection) reentry from transEarth orbit, its ablative heat shield able to withstand the temperatures and pressures of reentry at that speed and angle. The Shuttle Orbiter, on the other hand, can only tolerate (and then barely) reentry from LEO speeds and at a much shallower angle (about 1 degree versus Apollo’s 6.5 degrees). This is not insignificant; the reentry operation is extremely precise, especially for the Shuttle’s highly delicate TPS; staying to long or coming in too steep will cause a failure in the protection system which will (as illustrated by Columbia) result in catastrophic failure of the system. The only way the Shuttle could survive a cislunar reentry is by being slowed down to LEO speeds and a near-circular orbit, which would require substantially more fuel that would be practical to carry. (I haven’t worked out the numbers but it may well be more than is required to achieve orbit.)
Aside from the fact that the Delta IV Heavy doesn’t have the capacity to carry the Shuttle, empty, into LEO and isn’t man-rated (and with good reason), it would almost certainly be cheaper, more practical, and safer to design a purpose built system for cislunar travel. But then, NASA seems to have come up with an unconscionable pricetag for the largely existing-hardware-based CEV system (~$100B) and we can only expect from experience large cost overruns. But regardless, the Shuttle is just the wrong vehicle for that particular job; it was designed to be, and operates as, a heavy lift vehicle with passenger capability to and from LEO.
Stranger, I see both yours and Grelby’s points! However, given my misconceptions, yet with an eye for changing twenty-year-old technology out for somethign a little newer, I would think that if we were forced to use a shuttle as a main-flight airframe, it would be possible to do. . . but the cost would far outweigh the simple new design of a new orbiter.
But by God, if it can be done, let’s do it!!
Would the OMS have enough impulse to insert the shuttle into the Interplanetary Transport Network?
That’s essentially the same problem as getting to the Moon. Most of the network is the next best thing to free, but you still have to pay full price to get to the first object other than your origin. Basically, you’d fly out to the Moon using conventional means, but then instead of going into a stable orbit, you’d slingshot around it to points beyond.
Sort of lends a certain urgency to the concept of the “blue screen of death.” If they ever go with commercial software, they’ll probably have to change the name to the “blue screen of oh my god we are so fucked.”
OK here’s my shot at it.
1 - bring up in pieces and assemble another external tank and SRB’s,and refuel them there via multiple trips.
2 - Redesigned shuttle (Ok a lot of leeway here)
3 - Attach shuttle to orbital SRB & External tank.
4 - Using the SRB’s and ET, Off to the moon!!!
5 - SRB’s are jettisoned, some ET fuel is used for lunar orbital insertion.
6 - Cargo bay LEM launched and recovered
7 - The ET fuel is used to deorbit the moon and tank jettisoned
8 - Shuttle uses aerobraking manuver and OMS (perhaps main engines if they can be fired) to regain orbit needed to redock with ISS.
9 - After docking the shuttle is repaired in space and tiles replaced if needed for safe reentry.
10 - Shuttle refulled and sepperated from ISS for reentry and landing.
Here’s my 2nd shot at it:
1 - Build large transwarp drive space ship capable of landing.
2 - Load shuttle into new starship and fly it to the moon.
I’ve done some reading on the effects of cosmic radiation on commercial RAM devices. I don’t have a cite handy, but one study shows that an increase in altitude on Earth increases the number of “Single Event Upsets”. I’ve wondered if this was behind the original decision to use iron core memory on the shuttle.
The upshot of the studies were that faster, denser commerical parts are going to be more susceptible to cosmic radiation as a cause of single event upsets. Some of this can be offset by redundancy and some benefit can be gained from using error correcting RAM.
Anyway, this is another factor in the cost of design the shuttle replacement and in reutrning to the moon.
Surely it makes much more sense to keep the Shuttle for transit to a LEO space station, which serves as a base for launching vehicles onwards?
It’s been earlier noted that the Shuttle can’t take off from the moon. If, however, a runway were constructed (yes, I know…), perhaps with a ‘ski-jump’ a la Harrier, would the reduced lunar gravity mean that a fully-fuelled Shuttle could then launch?