Why abandon shuttles?

[MeteorWayne]

Edit: This was a reply to tanstaafl76, before Dragon's post...

Of course the tradeoff is that you have to use the aircraft to lift all that mass to 50,000 feet or whatever. While that's OK for light orbital satellite loads (which has been successful), or the Virgin Galactic suborbital flights (which has worked twice, IIRC, with a pilot only, no passengers), I'm not so sure it's really realistic for manned orbital or interplanetary craft, or heavy payloads such as ISS pieces or parts of interplanetry craft.

As you said, getting to orbital speed will require a lot of propellant even from 50 kft...and by it's nature, propellant is flammable and massive.

 

[tanstaafl76]

All the money that would be saved could be thrown into R&D for advanced propulsion, new, um..... *cough* space planes *cough*, etc.

I agree with you on the propulsion, but not on the space plane. In my always humble opinion, they should leave the ground-to-orbit stuff to private industry and the military. NASA's primary focus should be on the following:

1) Developing a new propulsion system for use in space that efficiently creates a constant 1G's worth of thrust on a spacecraft of substantial size for a long period of time with a relatively small amount of fuel.

2) Systems to protect crew members from radiation and micro-meteor impact during extended space flight.

3) Sustainable habitats for use on the Moon/Mars.

I'm worried that NASA is trying to design and handle every aspect of every new space mission, from launch pad to splash down, and it's not only unnecessary but winds up being a waste of their time, talent, and funding. A space plane program that really only gets them back to orbit would consume the entire agency and we'd be no farther than we were on the day of the last shuttle mission.

Of course the tradeoff is that you have to use the aircraft to lift all that mass to 50,000 feet or whatever. While that's OK for light orbital satellite loads (which has been successful), or the Virgin Galactic suborbital flights (which has worked twice, IIRC, with a pilot only, no passengers), I'm not so sure it's really realistic for manned orbital or interplanetary craft, or heavy payloads such as ISS pieces or parts of interplanetry craft.

As you said, getting to orbital speed will require a lot of propellant even from 50 kft...and by it's nature, propellant is flammable and massive.

Very good point MW, and I didn't mean to sound as if the problem had been solved. In fact a space plane may never be an attractive option for putting anything larger than small satellites in orbit, which is another reason why they should leave it to DARPA or the Air Force to figure out since they could get more use out of such capability than NASA would.

Even if they were able to come up with some manner of larger blended-wing-body space plane that could be hauled up to 50k feet by a giant plane (a la Antonov 225) you still have to come up with a way to get the space plane to a high enough speed to engage the scramjet which requires some additional form of propulsion, and then after you reach the limit of scramjet velocity you need yet a third method of getting it the rest of the way to orbit. Needless to say, it would be an extremely complicated proposition. I'm sure there are many better informed people around here on the subject, probably including yourself, that could describe what some proposed solutions are to these issues, but at best it would be an incredibly difficult challenge.

 

[bowman316]

If i had a billion dollars could i take a private flight to space?

Could Bill gates go to space next month if he wanted to?

 

[MeteorWayne]

You don't need anywhere near a billion. Trust me, despite their assurances, if you wanted to spend $50 million, you would be on the next Soyuz flight to the ISS. After all, that is what they intend to charge the US for flights after the current contract (with the shuttle as the other option) ends. If you wanted to pay 30 million more than the current rate, you'd get your flight.

 

[scottb50]

But the idea of a space plane is that you reduce the amount of rocket power needed to get to orbit by accelerating to very high rates of speed in the upper atmosphere using scramjet technology of some variety.[/quote]

That's where the idea falls apart, to do that would not come close enough to be worth while and the propellant needed in the atmosphere would reduce any payload to a useless amount. On top of that you would still need rockets anyway and they would have to do nearly the same amount of work they would have to do if launched from the ground.

 

[vulture4]

>>Actually a capsule with a LAS rocket can be 'saved' at any point from before liftoff all the way up. Hit the 'panic button' and off they go at 8 G's or more.

We lost one Apollo crew and nearly lost two more, and the LAS wouldn't have saved any of them. The LAS saved the Soyuz T-10 crew, but it also introduces additional failure modes; a Soyuz LAS also went off prematurely during ground safing after a scrub, killing at least one and injuring several other ground personnel. As for the T-10 fire, it might have been extinguished at LC-39, or had it propagated more rapidly (as it would in a solid fuel booster) there might have been no time to use it. Certainly if the hatch had still been open when the problem occurred, or had the ground crew been on station, the LAS would have been useless.

Every time you get on an airliner, you have no means of escape. Does a spacecraft need one? Rutan doesn't think so; his passengers don't even wear pressure suits. He believes that if you can't build a reliable vehicle and a reliable pressure hull, you have no business flying people into space.

There are times when redundancy is a reasonable strategy, but the NASA doctrine that redundancy (i.e. "fail safe") is generally equivalent to reliability has no basis in reliability engineering. Redundant systems increase complexity, weight, and cost, introduce additional failure modes, and protect only against failure modes that can be predicted. Inevitably failure modes that the redundant system doesn't protect against are de-emphasized or ignored. Obviously any reasonably safe design will eliminate any predictable failure modes, so real catastrophic launch vehicle failures are usually the result of failure modes that were either unpredicted or for which the likelihood was grossly miscalculated. A sophisticated but simple design, thoroughly tested in actual flight, and fully reusable with minimal maintenance, to reduce the chance of errors during construction, maintenance, and integration, remains the safest approach.

 

[ZenGalacticore]

It's cheaper to launch expendable rockets with return modules/capsules, plain and simple. NASA's known that it was cheaper with expendables since at least the late 1980s.

Each shuttle has to be reffitted, repaired, retooled, and gone over with a fine comb by a horde of engineers and technicians after each mission. $$$$$$$$. We've learned a lot tinkering around with them all these years, but it's time for an interim replacement. Ie, an interim phase of going back to what works the best for the least expenditure.

A new wave of reusables is sure to hit in the next few decades. During that time, materials and, more importantly, propulsion sytems will advance and begin to attain the speeds and efficiencies of our wilder(but not wildest ) dreams.

What ever became of the Aerospace Plane? They called it the X-1 back in the late eighties, IIRC.

Also, google the "magneto-plasma" rocket. It's a pretty cool concept that's in the works.

 

[JonClarke]

>>Actually a capsule with a LAS rocket can be 'saved' at any point from before liftoff all the way up. Hit the 'panic button' and off they go at 8 G's or more.

We lost one Apollo crew and nearly lost two more, and the LAS wouldn't have saved any of them.

Apollo 1 wasn't in a launch situation to is irrelevant to the discussion. I am not sure which are the other two you had in mind but had the the two major launch related incidents dureing Apollo led to a catastrophic failure (Apollo 12 lighting strike and Apollo 13 pogo) the LAS would have almost certainly saved the crew.

The LAS saved the Soyuz T-10 crew, but it also introduces additional failure modes; a Soyuz LAS also went off prematurely during ground safing after a scrub, killing at least one and injuring several other ground personnel.

One failure very early in the development history (third launch attempt of Soyuz). No other failures in more than forty years and 124 launches . That is good.

As for the T-10 fire, it might have been extinguished at LC-39

Since it wasn't at LC39 this is irrelevant. It is also unlikely as once a rocket has caugh fire it has almost never been extinguished.

or had it propagated more rapidly (as it would in a solid fuel booster) there might have been no time to use it.

Or perhaps there might have been. Either way the chances of escape with a LAS in such a sitiation are still miuch higher than without one.

Certainly if the hatch had still been open when the problem occurred, or had the ground crew been on station, the LAS would have been useless.

Not useless only irrelevant as it is not the situation a LAS is intended to deal with.

Every time you get on an airliner, you have no means of escape. Does a spacecraft need one? Rutan doesn't think so; his passengers don't even wear pressure suits. He believes that if you can't build a reliable vehicle and a reliable pressure hull, you have no business flying people into space.

Since Rutan is only in the business of flying people in suborbital hops to 100 km how much weight does his opinion carry?

There are times when redundancy is a reasonable strategy, but the NASA doctrine that redundancy (i.e. "fail safe") is generally equivalent to reliability has no basis in reliability engineering. Redundant systems increase complexity, weight, and cost, introduce additional failure modes, and protect only against failure modes that can be predicted. Inevitably failure modes that the redundant system doesn't protect against are de-emphasized or ignored, i.e. any catastrophic failure of the Ares before hatch closure and with less than four minutes warning. Obviously any reasonably safe design will eliminate any predictable failure modes, so real catastrophic launch vehicle failures are usually the result of failure modes that were either unpredicted or for which the likelihood was grossly miscalculated. A sophisticated but simple design, thoroughly tested in actual flight, and fully reusable with minimal maintenance, to reduce the chance of errors during construction, maintenance, and integration, remains the safest approach.

Obviously NASA (and Energia, and CSA) think differently.

Jon

 

[vulture4]

>>Since Rutan is only in the business of flying people in suborbital hops to 100 km how much weight does his opinion carry?

So Apollo I and ASTP (within about 30 seconds of loss of crew when Stafford managed to keep himself conscious long enough to activate the self-righting floats), would have been safe if they had just been suborbital hops? I'm not aware that flight to 110km is intrinsically safe, any more than flight to 10km is intrinsically safe. But a reliable design can make it safe. Burt Rutan graduated third in his class at Cal Tech, designed at least a dozen major new aircraft, and won the X-prize. He knows exactly how much energy it takes to get into orbit, but he also knows how much money it takes, and that it isn't practical to build a new launch vehicle for each mission. That brings us back to the original topic of this thread. Human spaceflight on ELVs is much to expensive to be practical, and Ares will not change that. Why abandon shuttles? Are they intrinsically unsafe and expensive, or was it just a poor design? Rutan is getting experience in the suborbital regime, but if his designs prove to be reliable and economical, there is no reason the air-launched concept can't evolve to orbital flight. Of course that might require a new, specialized launch aircraft, something neither NASA nor Orbital Sciences atttempted. Rutan's objective is to build manned spacecraft that are practical, and he has recognized that this requires they be fully reusable, not just salvageable.

 

[Swampcat]

...or the Virgin Galactic suborbital flights (which has worked twice, IIRC, with a pilot only, no passengers...

Just to set the record straight, there were three flights of Spaceship One above 100km. The first was a test flight, while the next two were the actual X-Prize flights.

 

[job1207]

The answer is this. The next generation of reusable spacecraft will be flying again. The X37B is set to launch http://www.domainb.com/aero/space/launc ... rbiter.jpg for Jan 2010. ) Someone posted that it will carry 5 tons. That is not correct. It weighs five tons and has a 4x7 foot area that could function as a payload bay. However, this is just an experimental vehicle. The actual vehicle will be larger if they ever build it.

The STS is too expensive to maintain. They are continuing the reusable effort. Perhaps they will make it cheaper over time. Right now expendable is the least expensive way to go to space. After the ISS is finished, there will be no unique role for the STS. That said, even this role of building the ISS could have been done by reusable spacecraft. The fact that the modules were built to fit in the shuttle payload bay is akin to the fact that the X37 was ALSO built to fit in the shuttle payload bay. That was the vehicle in use at the time. The X37 is about to be launched aboard an Atlas V.

As far as the STS is concerned, they should have been closing out a perfect record of flights, because of their strict attention to Quality assurance. Work everything so that you can approach zero defects. That approach is always the least costly approach.

Private efforts to develop a totally reusable craft are ongoing. As noted, Rutan is closest to going totally reusable. It is unknown if they have started actually building an orbital aircraft. Certainly, they did not get close enough to building a craft to win the COTS competition. So, I tend to doubt that they have the money to build a LEO reusable vehicle. They will get the money from suborbital passengers to fund further development. We will see how far that money takes them.

Musk IS in orbit and continues to develop his somewhat reusable program. The Falcon first stages will be retrieved and reused if they follow their original plan. Also the re rentry vehicle will be re used.

The least expensive way to launch the ISS would have been on the Saturn V. It would only have taken a handful of flights. Then you would have been wanting for a mission and we would already have gone to the Moon and Mars. Reworking the vehicle so that the first stage burned longer would eliminate the need for a second stage and decreased the cost. ( That would require shutting off quite a few F1 engines as you go up.) See Saturn INT 20

Going forward, the country is building the Ares V. That will work for Moon and Mars missions. I wonder if it will rendezvous with Ares 1 or Dragon, we will see. I am betting on Dragon.

 

[JohnLatour]

Is there any specific cargo to use?

 

[BrianBoru]

An outright dismissal of a shuttle delivery system is myopic. However, a government agency like NASA has a finite budget, and when setting a 'vision' it has to look years down the line, but commit to that vision today, ergo it can not 'do it all'.

Present day banking and automotive American structures notwithstanding, private enterprise (many diverse entities looking at the same problem/opportunity) may ultimately be the best venue for advancing the shuttle concept. Especially in light of the fact that every time there is a new administration in Washington, NASA's commitments usually become anything but.

As for the current shuttles, I remember seeing a documentary on them, where an engineer said that most of the wiring (1960s and 70s technology) has been left alone in the more inaccessible areas, because to begin 'playing around' with them, may lead to unforeseen problems and complications which may lead to a shuttle becoming flight unworthy.
That's a $3.5 billion dollar gamble no one wants to put their signature on.

Space exploration for humanity is still in it's infancy, there's plenty of room for public and private initiatives, it's just a question of who writes the checks, how big they'll be, and is their sufficient room to allow for failure?

Also, the we-want-it-now generation, will have to devise and accept long-term planning and execution of space related initiatives.

 

[CalliArcale]

You don't need anywhere near a billion. Trust me, despite their assurances, if you wanted to spend $50 million, you would be on the next Soyuz flight to the ISS. After all, that is what they intend to charge the US for flights after the current contract (with the shuttle as the other option) ends. If you wanted to pay 30 million more than the current rate, you'd get your flight.

I believe the current going rate is $30 million, and if you pay an extra $5 million, they'll bump you up to the head of the queue. That's how Simonyi managed to go twice -- he paid extra to cut in line for his second flight.

 

[andrew_t1000]

I don't understand why the Shuttle can't be refurbished.
How old is the oldest 747?
How about a complete refit?

On another note,
What the hell happened to Venture Star?
The technology demonstrator X-33 developed a crack in the composite liquid hydrogen tank and that was all she wrote!
What the hell?
When you think of all the work and money that went into the design and development of the craft itself and the Aerospike engines it seems another huge waste of funds and opportunity.
Venture Star would have been cheaper to run, safer to fly, lift more payload.
Now NASA has decided to recycle Apollo technology as their manned space flight solution.
NASA seem really like spending money on "vapour ware".
$11 billion on ISS mockups and feasability studies.
Recreating long term isolation studies for manned missions to Mars and beyon, work the US Navy, Airforce and Army had already done.
That stupid "Jet pack" concept thing they trotted out a few years ago, then some perky NASA engineer said, "All we have to do now is make it work!"
That incredibly expensive Mars base mock up at Goddard Space Flight centre, another perky NASA engineer quipping, "This is what we'll be sending to Mars, but it's important to know the optimal place for the water coolers"

There are many more examples, but NASA seems to be so diffused across to many disciplines.
As we say here in Australia, "They need good kick in the arse!"

[/list]

 

[seth_381]

I feel the same way reusable shuttles are the but if you look back the reason VentureStar was canceled was $$$ it is simple NASA just doesn't have $$$ for anything new. I asked myself once did they think in 1981 they would be flying the same spacecraft 30 years later. They probably didn't but they are. If it were up to me I would have both Ares/Constellation and the Shuttle flying in concert.

 

[MeteorWayne]

Of course, you can't pay for both....

 

[andrew_t1000]

When the X33 had its oopsy with the liquid H2 tank, Lockheed stated categorically "they were still comitted to the project", as did NASA.
One cracked tank and the whole damn thing got shelved!
Where did all that cash go?
What about the engines, they built quite a few, where are they now?