Why the ironclad cutoff for the space shuttle?

[FoieGrasIsEvil]

@mks57

That isn’t a major problem. Ground equipment has been upgraded/replaced as needed when it is too expensive or difficult to keep it running. As long as you can still get parts, there’s nothing wrong with using “obsolete” equipment. Many of the old systems actually are more reliable and perform better than their replacements. They were designed to do a specific job, in comparison to modern COTS (commercial off-the-shelf) equipment that has been adapted to do the same job.

See: B-52 bomber.

[FoieGrasIsEvil]

@Harmonious Discord

Get real. The light bulb comparison is bullshit. I gave a very good reason for NASA to want to retire the old shuttles. The shuttles are old. You can argue with NASA over keeping the old design if you like, I don’t plan on taking the bait.

It’s one thing to entirely scrap the old design, it’s another to take from it what works and implement it in a new design. The OP is asking why there has to be an absolute cutoff time for the shuttle. Other than safety concerns, I can’t see a reason to arbitrarily stop all shuttle flights for a new design, particularly if there’s going to be a gap between retiring the old shuttle fleet and whatever vehicle replaces it.
Why can’t it be a “phasing in, phasing out” scenario?
maybe it is and I am ignorant. I don’t work for NASA

[R.P.McMurphy]

@carnivorousplant

A bad analogy. You are junking your Corvette and buying a VW beetle.
It’s got wings. It lands like an airplane. It’s cool. We are going back towards the capsule that Chuck Yeager described as “sitting in monkey shit.”

A redesign where the shuttle sits above the tank and boosters would be a better idea for low Earth orbit.

OK, I am not an aerospace engineer. It’s very complex and at some point I have to trust the judgment of those that have spent their careers thinking it through and putting their ideas and judgments on the drawing board. When the Space Shuttle got deployed it was already obsolete but lead times make that unfortunate situation a practical fact. The same will hold true for the next generation.

Chuck Yeager is a great American (I have met him and admire him) but space technology is such that a fighter jock is not the answer to what is needed to explore space.

Another bad analogy:

Paddle shifters are far superior to a clutch and stick shift but there are cementheads out there that will argue otherwise.

[FoieGrasIsEvil]

@Stranger On A Train

It’s not so much cost as budget planning that mandates a hard cutoff of funding for Shuttle missions. The cost of operating the Space Transportation System (STS) Shuttle isn’t just the expense of preparing individual launches themselves but also roughly fixed cost of maintaining the overhead for launch facilities and trained personnel. Indeed, if the STS program was able to sustain more launches per year, the costs of this overhead would be amortized over more launches and individual launch costs would be more competitive with expendable launch vehicles. It is necessary to cut this off in order to start funding production-level development of the successor Constellation system and facilities to be used therefore.

In addition, one of the selling points for the Ares launch system family used for Constellation is that it uses Shuttle-derived hardware which allows for adaptation of existing launch and integration facilities, ostensibly saving money versus building up new facilities from scratch. (The reality that it almost always costs more to make significant modifications to a system than to just build purpose-built equipment from scratch rarely penetrates the fictional, PowerPoint-dominated world of conceptual proposals.) Naturally, this means that you have to take the existing STS facilities out of operation and allow time for modification and pathfinding for your new system. While you are doing this you don’t have any way to support STS launches. Hence, a cutoff date and launch capability gap.

As for the “heat tile problem seems to be solved” I have to disagree. There is now a broad acknowledgment of this previously known problem by NASA management, but the solution–such as it can be said to exist at all–is a hacktastical risk mitigation plan of questionable value that increases cost and maintenance requirements, decreases manpower available for actual mission-related activities, and would likely not have fixed the problem which resulted in the catastrophic re-entry failure of Columbia, to wit a puncture in the reinforced carbon-carbon leading edge thermal protection which allowed overheating and structural collapse of the wing structure. Should another puncture of similar size occur, the only credible response would be to launch a rescue mission which (hopefully) would not experience the same failure. Like the post-Challenger In-Flight Crew Escape System (ICES) bail-out abort option, it exists primarily for management to say, “We’ve done everything practically possible to reduce crew hazards,” without actually fixing the problem (which would require major redesign and refit with likely reduced mission and lift capability).

Nor is the TPS puncture problem by any means the only standing safety issue with the Shuttle, as has been demonstrated in the post-Columbia safety-aware era; we’ve seen problems with leaking fuel tanks, cracked fuel lines, faulty switches, et cetera all of which have resulted in costly launch delays. Of course, these issues are part and parcel of expendable launch vehicles as well, and despite two failures the STS actually has quite a good history of completely successful missions and returns compared contemporary LVs like Titan III/IV, Delta II/III/IV, Atlas II/III; in fact, I believe the only American heavy launch systems with a better launch success rate are the Atlas V (with only about a dozen launches since introduction) and Saturn family. But because of the cost and hazard to personnel of the Shuttle, and the fact that it endures risk not only on the way up but also on the return flight, the level of scrutiny is higher than for expendable vehicles, and failures are extremely expensive both in increased hazard mitigation efforts and political/public support for the space program overall. When Boeing tilts a Delta over, Lloyd’s ups the premiums for the next few launches and mission assurance organizations get more funding to identify problems before they become failures. But when the Shuttle comes apart like a cheap gold watch, everything stops, Congressional hearings are held, and 60,000+ workers hold their breath to see if their careers are canceled along with the STS program.

Letting the Russians take care of getting American astronauts up to the ISS and back down may seem kind of risky, but in fact there is actually little we need the ISS for other than a place to go to. As scaled back as it has become, it essentially exists for the purposed of being a way-station to nowhere, and if we had to stop sending people up there for a few years over a disagreement about the quality of Russian versus American vodka, the net effect would be to limit the career ambitions of a few members of the astronaut corps and support personnel. Compared to the cost of running two concurrent manned launch vehicle programs, there’s no question, especially given the hard limitations of NASA’s budget.

The compromises built into the STS have more than cost impacts; indeed, to justify building the Shuttle at all, artificial restrictions were placed upon the use of expendable heavy launch vehicles in order to essentially give business to the STS program, i.e. requiring the Air Force and NRO to use the Shuttle as the primary platform for orbital delivery of reconnaissance satellites, which in turn drove the payload size and cross-range requirements on the Shuttle which in turn forced the use of lower safety margins and sub-optimal design. That shell game finally came apart along with Challenger, and the Air Force washed their hands of NASA launch deliveries and Blue Shuttle, but the compromises still remained, built into the design. Dennis R. Jenkins’ Space Shuttle: The History of the National Space Transportation System The First 100 Missions goes into extensive detail on early Shuttle development and the politics behind it for those who are really interested.

As for doing better today, the Constellation program is really a return to Apollo-era concepts (expendable two stage heavy launch vehicles with an additional Earth departure motor for transLunar injection, blunt-arsed conical capsule, separate lunar landing module, et cetera) updated to use modern avionics. This is essentially what we could have anticipated having in the 'Eighties and 'Nineties had we continued with the Apollo Plus and Apollo Applications programs. Far from doing better today, we’re just aspiring to do better than what could be done in the 'Seventies. It’s the smart, minimum risk and minimum development approach, but it can hardly be considered more advanced; and more disappointingly, this isn’t being viewed as an interim solution to a more mature and capable system, but the foundation for an entire class of human space launch vehicle operating for the next three or more decades.

Stranger

Good stuff, thank you.

[FoieGrasIsEvil]

@Spartydog

Do you want to spend all of your money repairing and patching your 1990 Camry (which was a great car and very utilitarian) or buy a new 2010 car with all of the technical advances like traction control, accident prevention systems, GPS, satellite radio, side air bags, improved emission systems, etc., etc.

It’s like the Hubble telescope that NASA wants to retire. Yea, Hubble gave us a lot of neat pictures and people got upset when they heard that it might get shut off. It didn’t occur to the general public that NASA wanted spend their limited budget to replace it with something that was far superior.

Space exploration is suppose to be a cutting edge endeavor. Let the guys that know what the engineers that are designing the future can do, rather than trying to tell them to patch and repair their obsolete designs.

I agree but sometimes when suckling on the government teat, budgets are budgets.

[gravitycrash]

Stranger makes a good point but even though I think the ISS is a turkey we need to get more experience living in space. Not just living there but assembling complex machines in a vacuum.
I consider the ISS as a 7 year old child’s erector set. We have to start somewhere.

[FoieGrasIsEvil]

@carnivorousplant

A bad analogy. You are junking your Corvette and buying a VW beetle.
It’s got wings. It lands like an airplane. It’s cool. We are going back towards the capsule that Chuck Yeager described as “sitting in monkey shit.”

A redesign where the shuttle sits above the tank and boosters would be a better idea for low Earth orbit.

i wondered why we are reverting rather than improving. the Shuttle is a fantastic design, albeit costly, so why can’t we move forward with a vehicle design that takes the best of both? A reusable vehicle with disposable boosters that has modernized hardware/software yet exceeds flight expectations and safety measures over the currently obsolete design?

[FoieGrasIsEvil]

@gravitycrash

Stranger makes a good point but even though I think the ISS is a turkey we need to get more experience living in space. Not just living there but assembling complex machines in a vacuum.
I consider the ISS as a 7 year old child’s erector set. We have to start somewhere.

I often wonder why we are trailing the technology curve in this area if we are truly serious about colonizing space as an alternative to living on Earth, which is a realistic possibility sooner rather than later, in Vulcan years…

[gravitycrash]

@FoieGrasIsEvil

I often wonder why we are trailing the technology curve in this area if we are truly serious about colonizing space as an alternative to living on Earth, which is a realistic possibility sooner rather than later, in Vulcan years…

Ah yes. In Vulcan years I would maybe still be alive to see humans land on Mars. As it looks right now I’ll be lucky to see another manned flight to the moon.

[FoieGrasIsEvil]

@gravitycrash

Ah yes. In Vulcan years I would maybe still be alive to see humans land on Mars. As it looks right now I’ll be lucky to see another manned flight to the moon.

hey, don’t fret, NASA may yet trot out a dog-operated RCV for Mars within the next decade.
Since we’re being so supposedly reliant upon the Russians and all, we might as well revert to Sputnik pilots.

[Tuckerfan]

@carnivorousplant

The Wiki article mentions since they are reusable “…would allow NASA to make a fleet of block I.”

Yes, but that has nothing to do with NASA having enough in the budget to build an extra one that will just hang like a tick on the bottom of the ISS.
The last time I bothered to crunch the numbers, NASA’s current budget worked out to about $3 billion in 1966 dollars (when it had the largest budget in it’s history). What we’re asking NASA to do is to go to the Moon and do unmanned exploration of the cosmos for next to nothing.

@Spartydog

It’s like the Hubble telescope that NASA wants to retire. Yea, Hubble gave us a lot of neat pictures and people got upset when they heard that it might get shut off. It didn’t occur to the general public that NASA wanted spend their limited budget to replace it with something that was far superior.

Not quite correct. The Hubble’s replacement, like the shuttle, is due to come on line some years after the Hubble would go “tits up”, and unlike the shuttle, the Hubble can be upgraded to work better than what it is presently doing, so the Hubble will continue to churn out good science, while the shuttles will only be able to do about the same as what they’re doing now (which isn’t much in the grand scheme of things).

Never forget that the shuttle is a compromised design, and the longer they keep flying, the greater the risk of someone dying is. It is, admittedly, better than nothing at all, but if I had to choose how someone dies, and the choice was between them dying while driving a milk truck or dying while pushing the limits of human knowledge, I’d choose the latter, since their death would at least have more meaning. (And I’d happily strap myself into either death trap rather than send someone else.)

If you want a decent space program, you’re going to have to let your Kongress Kritters know! (Find your “representative” in the House here. Your Senator here. Let McCain know how you feel about the space program here. Obama. Hillary.) IMHO, it is past time we got angry about the decrepit nature of the space program, and we should adopt Malcolm X’s “By any means necessary” stance towards getting our asses off this rock and out in to the cosmos where we belong. For a lot less than we’ve spent on The War Against Terror in Iraq we could have:

• Giant robot
• The operating Moonbase
• Orbital hotels
• Spain-Morrocco tunnel
• New SST
• New York-LA Maglev
• Floating city
• An android army
• Blasters and railguns
  And still have money to burn. Cite. Space geeks shouldn’t be merely irritated at the current state of affairs, they should be downright out for blood. And I wouldn’t blame them a bit if the next time they saw someone complaining about the pocket change NASA get’s they beat the shit out of them. But if you don’t bitch to your elected representatives now, then you’ve got no right to complain twenty years from now when the Chinese are running amok on the Moon and they won’t sell you a ticket.

[Stranger_On_A_Train]

@FoieGrasIsEvil

i wondered why we are reverting rather than improving. the Shuttle is a fantastic design, albeit costly, so why can’t we move forward with a vehicle design that takes the best of both? A reusable vehicle with disposable boosters that has modernized hardware/software yet exceeds flight expectations and safety measures over the currently obsolete design?

The American Shuttle, and indeed any winged shuttle design is going to have the problem of intense heating at the leading edges due to ram pressure while shedding momentum during re-entry. Far from a “fantastic design” the American Shuttle Orbiter is highly problematic even in concept, with aerodynamic loads during ascent near max Q alpha pushing the wings to within a few percent of positive structural margins. (This is why the Orbiter inverts as it pitches over; increasing the margins would result in a substantially heavier vehicle with reduced payload.) The STS also has the inherent problem of lacking credible abort modes during the most risky part of ascent. From the time that the Solid Rocket Boosters (SRB) are lit off to when they are expended, there simply is no feasible way to abort without causing the Orbiter to break apart and applying high shock and G loads to the crew; even if you could safely detach the SRBs, the resulting change in thrust would destabilize Orbiter and tank and the resultant aeroloads would cause a break-up of the Orbiter similiar to what happened with Challenger. In comparison, the Soyuz/Gemini/Apollo/Constellation concepts have credible and testable escape modes in every regime from pre-ignition through orbital insertion, thanks to the use of a launch escape system (a solid rocket attached to the capsule during the early stages of launch which can pull it out of the way of a runaway booster, and then be ejected for the subsequent deployment of landing parachutes or parawings). The Russian Buran shuttle system, which is superficially very similiar to the American STS but has some substantial differences, addresses a few of these problems but suffers identically from others, and the Soviets clearly found it too expensive and/or risky to operate, preferring their mature and reliable Soyuz SLV and capsule. Once you’ve given up on a single-stage or hybrid-stage/1.5 stage to orbit spaceplane concept (see the cancelled Rockwell X-30 NASP, the Lockheed Martin X-33/VentureStar, the HOTOL and Skylon spaceplanes, et cetera) the utility of a winged vehicle is limited to providing cross-range (the ability to make a course change lateral to the nominal trajectory), which actually drove the wing size of the American Shuttle Orbiter past what was recommended in initial conceptual proposals in order to obtain once around polar orbit capability for use by the Air Force, which was no longer needed following the cancellation of Blue Shuttle. If you aren’t using wings for lift during launch, they’re pure dead weight, and make up a substantial portion of the dead weight budget of the Shuttle Orbiter.

A true lifting body re-entry vehicle like X-38 can help to distribute stress and prevent edge heating (thus relying on less brittle thermal protection systems than the fragile reinforced carbon-carbon composites used on the leading edges of Orbiter wings and that were famously punctured in the case of the Columbia catastrophe), but you can obtain a modest amount of cross-range with a blunt-body conic or bi-conic while obtaining substantial safety margins and a long legacy of completely successful flight history. A blunt-body capsule, far from “reverting”, may be the ideal for re-entry of manned space capsules. Certainly the radical Chrysler SERV bi-conic SSTO shuttle proposal was based on the concept of using blunt body mechanics to avoid the necessity of cutting edge thermal protection.

@carnivorousplant

A redesign where the shuttle sits above the tank and boosters would be a better idea for low Earth orbit.

Without going into extensive technical detail I’ll just note that trying to mount something the size and mass of the Space Shuttle Orbiter on top of a booster stack is nothing short of impossible from a structural point of view. The vibrational characteristics and resulting bending modes from such a design would tear the thing apart before it even managed to come off the pad, even before you take into account issues with wind shear and aerodynamic loads. You would need an entirely different vehicle–something much smaller, like the X-38 or the CEV–to transfer personnel than you would use for heavy boost, which is, in fact, the general concept of what NASA is persuing with regard to the Constellation program. This will also certainly be cheaper than a man-rated heavy lift vehicle, and will again allow for some means to pull the personnel capsule/shuttle clear of the launch vehicle in the case of an early-stage abort.

Stranger

[Tuckerfan]

@Stranger On A Train

A true lifting body re-entry vehicle like X-38 can help to distribute stress and prevent edge heating (thus relying on less brittle thermal protection systems than the fragile reinforced carbon-carbon composites used on the leading edges of Orbiter wings and that were famously punctured in the case of the Columbia catastrophe), but you can obtain a modest amount of cross-range with a blunt-body conic or bi-conic while obtaining substantial safety margins and a long legacy of completely successful flight history. A blunt-body capsule, far from “reverting”, may be the ideal for re-entry of manned space capsules. Certainly the radical Chrysler SERV bi-conic SSTO shuttle proposal was based on the concept of using blunt body mechanics to avoid the necessity of cutting edge thermal protection.

Wasn’t there a winged concept with a cooling fluid circulated through the leading edges of the wings to deal with the heat?

Without going into extensive technical detail I’ll just note that trying to mount something the size and mass of the Space Shuttle Orbiter on top of a booster stack is nothing short of impossible from a structural point of view. The vibrational characteristics and resulting bending modes from such a design would tear the thing apart before it even managed to come off the pad, even before you take into account issues with wind shear and aerodynamic loads. You would need an entirely different vehicle–something much smaller, like the X-38 or the CEV–to transfer personnel than you would use for heavy boost, which is, in fact, the general concept of what NASA is persuing with regard to the Constellation program. This will also certainly be cheaper than a man-rated heavy lift vehicle, and will again allow for some means to pull the personnel capsule/shuttle clear of the launch vehicle in the case of an early-stage abort.

Stranger

There was a concept which had a small winged craft mounted to the top of what looked like a Delta rocket that NASA was kicking around at one time. the other thing that you didn’t mention is that mounting the current shuttle on top of the stack would involve ripping the main engines off the shuttle and mounting them (presumably) on the tank, as those engines are needed to get the shuttle off the ground.

[wolfstu]

@Tuckerfan

There was a concept which had a small winged craft mounted to the top of what looked like a Delta rocket that NASA was kicking around at one time. the other thing that you didn’t mention is that mounting the current shuttle on top of the stack would involve ripping the main engines off the shuttle and mounting them (presumably) on the tank, as those engines are needed to get the shuttle off the ground.

Just for fun, I’ll mention that the cancelled Hermes vehicle was just this – a smaller, winged craft mounted on top of Ariane 5, which has a liquid-fuelled main engine below a big cryogenic tank, and a pair of solid boosters.

The result is something like Stranger on a Train describes: Hermes was canned, but the rocket itself had merit, and it became Europe’s heavy launcher. Eventually, ESA developed a cargo-only spacecraft to use the same launcher and carry supplies to orbit for manned missions, while the crews themselves are launched separately (by US Shuttle or Russian Soyuz).