Unmmannedspaceflight Ares V missions, How would a big rocket change the paradigm Options

[Jim from NSF.com]

There is no industry standard for man rating only NASA's "guidlines" which it doesn't even follow

[nprev]

Actually, the Shuttle is a beast unto itself when it comes to man-rating a launch vehicle. As designed, it cannot be flown unmanned -- you would need to make several major modifications to it if you wanted to fly it unmanned, which were considered to be too expensive (and, in some cases, dangerous) to build in.

A while back, I speculated about using the Shuttles as unmanned delivery trucks for the ISS after 2010...basically flying them till they burn up or blow up someday. Other than upgrading the autopilot to function more like an RPV, what other mods would be needed, oDoug?

[David]

There were several different missions proposed to make use of the amazing capability provided by the Saturn V -- Mars landers, outer planet flybys and orbiters, Venus orbiters... a plethora of missions that could all benefit from the incredible lifting capability of the massive Saturn.

They all ended up shelved. Mostly because a Saturn V was immense in every respect, including its cost. It became glaringly obvious that no one was willing to spend the kind of money it would cost to buy a Saturn V to launch their unmanned probe.

Only 15 Saturn Vs were ever built, 13 of which were used -- so nobody ever was given the choice of deciding whether or not to spend the money on a Saturn V. If full-scale production of Saturn Vs had been entered upon (with the prospect of creating scores or hundreds of Saturn Vs, over a period of decades) then economies of scale would certainly have lowered the per-launch cost. I'm sure it would still be costly, but then there would be the opportunity to launch something really big, really far, really fast. You can't get what you don't pay for.

[AscendingNode]

I was wondering if there are missions that aren't being considered because of current limitations of launch vehicles...

When bigger rockets become available, it could be a paradigm shift in terms of the priorities for exploration. Would Europa still be #1 priority if Neptune were possible? Would Mars be as important if it were as easy to get to Jupiter as Mars?

[dvandorn]

Only 15 Saturn Vs were ever built, 13 of which were used -- so nobody ever was given the choice of deciding whether or not to spend the money on a Saturn V. If full-scale production of Saturn Vs had been entered upon (with the prospect of creating scores or hundreds of Saturn Vs, over a period of decades) then economies of scale would certainly have lowered the per-launch cost. I'm sure it would still be costly, but then there would be the opportunity to launch something really big, really far, really fast. You can't get what you don't pay for.

True. The problem is that there was literally no market for Saturn Vs, aside from Apollo and Skylab. I seem to recall that NASA floated the prospect around to every potential market, including planetary probe developers and commercial interests (comsats, powersats, etc.) and got no takers. Even after estimating the economies of scale that you mention.

There was, and is, simply not a paying market for huge launchers. The only reason the Ares V is being developed is to support Constellation/Orion -- heck, there have still been no buyers for the Atlas V Heavy or the Delta IV Heavy. If no one is willing to pay the costs for those vehicles, I doubt the Ares V is going to be used for much of anything beyond Orion.

-the other Doug

[David]

True. The problem is that there was literally no market for Saturn Vs, aside from Apollo and Skylab. I seem to recall that NASA floated the prospect around to every potential market, including planetary probe developers and commercial interests (comsats, powersats, etc.) and got no takers. Even after estimating the economies of scale that you mention.

What timeframe are you referring to, Doug? '63-'65? Or earlier?

[dvandorn]

There were a variety of discussions beginning in 1961 (when the Saturn family began to be designed) through 1969-70, when the Saturn assembly lines were shut down. And while many types of payloads for the Saturn series were identified, when it came down to funding programs, cheaper (though less capable) alternatives such as the Titan III family of launchers won the day.

Remember, in the 1960s, the Atlas-Agena was the Delta II of the day -- the cheapest thing available that would get a few hundred kg out of LEO. If you needed to boost more, you had the Atlas-Centaur, which was more expensive but required for larger probes. (Sort of like the basic Delta IV or Atlas V -- and about the same degree more expensive). By the late 60s, you had the Titan III family, including the Titan-Centaur, which was just about the same in lifting power as a Saturn IB. The Titan III family were even more expensive than the Atlas family, and so only very large flagship missions (with accordingly large budgets) could afford to use them.

Now, as we've gone up through the Atlas to the Titan III families, costs have ranged to be comparable (in values corrected for inflation) on the low end to what a Delta II used to cost, and on the high end what a Delta IV Medium or an Atlas V Medium would cost today.

Then came the Saturns. A Saturn IB cost more than a hundred million dollars, in 1966 dollars. A Saturn V cost a third of a billion. (I'm quoting numbers by memory, but I think I'm in the right ballpark.)

Even with economies of scale, we're talking about, in 2007 dollars, spending three to five billion dollars for your launcher alone.

Any wonder no one ever decided to spring for a Saturn for their Mars or Jupiter mission?

However, there is nothing wrong with making the most of the designs and experience that came out of the Saturns. Heck, the tools and dies for the S-IC were kept warehoused for a number of years, IIRC. Some Saturn processes could probably be improved on, of course -- the manufacture of the S-II's forward bulkhead, for example, involved detonating small bombs behind a sheet of aluminum to press it into a rigid form on the other side. (I kind you not -- and it was hailed as a brilliant solution to a tough problem in its day.)

It would seem that detailed plans and some tools and dies were also saved for the J-2 and F-1 engines, as well. The J-2X is supposed to be an upgraded J-2, based in large part on the older engine, and I know I have seen early proposals for the Ares V which involved actually building von Braun's already-designed, uprated F-1A engines (1.8 to 2 million pounds of thrust, as opposed to the 1.5 to 1.55 million-lb-thrust F-1). (Yeah, I know, it ain't Newtons. So sue me... ) So, some legacy Saturn hardware/designs could ease the development path for Ares.

I must say, though, that I'm happy with the decision against using SSME's in the Ares V. A big part of the SSME design is its throttleability, which is only required on Shuttle because of the need to manage aerodynamic stresses on the stack during ascent. The Ares V has absolutely no need for throttleable main engines -- to use them would only increase expense. And to remove the throttleability, you'd need to redesign the things so much that you're in essence creating a brand new engine.

-the other Doug

[ugordan]

I must say, though, that I'm happy with the decision against using SSME's in the Ares V.

All right. I already asked this in another thread, but wasn't the Ares V supposed to use the cheaper RS-68 Delta IV engines? It was deemed the SSMEs were too complex and costly, besides they wouldn't be getting them back for refurbishment as was the case with the Shuttles. RS-68 is a less efficient engine, but IIRC much simpler and cheaper. Since the Ares V was never meant to launch humans, it doesn't need to have man-rated engines badly.

EDIT: Duh... Maybe next time I could actually read what you wrote. Decision against SSMEs, that makes sense. I'm quite happy with that decision, too. SSME was engineered for sea-level to vacuum operation so it probably also sacrificed a thing or two in efficiency. RS-68 was designed to be the booster engine, similar to what F-1 used to do so it's logical expansion ratios, mixture ratios could be optimized for atmospheric flight.

[Jim from NSF.com]

I must say, though, that I'm happy with the decision against using SSME's in the Ares V. A big part of the SSME design is its throttleability, which is only required on Shuttle because of the need to manage aerodynamic stresses on the stack during ascent. The Ares V has absolutely no need for throttleable main engines -- to use them would only increase expense. And to remove the throttleability, you'd need to redesign the things so much that you're in essence creating a brand new engine.

-the other Doug

The RS-68 is throttleable

[Jim from NSF.com]

A while back, I speculated about using the Shuttles as unmanned delivery trucks for the ISS after 2010...basically flying them till they burn up or blow up someday. Other than upgrading the autopilot to function more like an RPV, what other mods would be needed, oDoug?

Many of the required operations of the orbiter are manual. Opening payload bay doors, starting and shutting down the APU's, deploying payloads, etc. The whole avionics architecture needs an upgrade

[Jim from NSF.com]

I was wondering if there are missions that aren't being considered because of current limitations of launch vehicles...

Actually there are more LV options now, especially wrt performance, than in the past

[dvandorn]

A while back, I speculated about using the Shuttles as unmanned delivery trucks for the ISS after 2010...basically flying them till they burn up or blow up someday. Other than upgrading the autopilot to function more like an RPV, what other mods would be needed, oDoug?

In addition to Jim's excellent answer, there is one major item that the Shuttle designers made manually controlled, for *very* good reason. The landing gear.

You see, when the gear are deployed, they cannot be retracted without external help. Since landing at 300+kph without one or more of the gear down would destroy the vehicle, the gear are designed with a lot of "positive deployment" features. The short version is, once they are down, they are staying down until external hydraulics are attached to retract them.

So, if the gear were ever to deploy in orbit, you would never get that orbiter back. You can't make a successful entry with the gear doors open. That's why the gear are protected with a separate arming switch and a manual circuit breaker. If the gear were capable of being automatically deployed, that would open up te potential for a short circuit or a bad line of code (or just an electrical surge) to cause the destruction of a multi-billion-dollar vehicle.

Yeah, you could always automate the landing gear for unmanned flight. But you'd degrade its capability for re-flight by a small but significant fraction -- and by NASA's rules, you'd not again be able to man the spacecraft in that configuration, since it opens up a few single-point failure modes that would result in loss of crew.

-the other Doug

[dvandorn]

I was wondering if there are missions that aren't being considered because of current limitations of launch vehicles...

When bigger rockets become available, it could be a paradigm shift in terms of the priorities for exploration. Would Europa still be #1 priority if Neptune were possible? Would Mars be as important if it were as easy to get to Jupiter as Mars?

It doesn't matter, up to a certain point, how much mass you can loft. Jupiter will *always* be harder than Mars (for a lot of reasons, including its distance from the Sun and the radiation environment). Neptune will *always* take a lot longer to get to than Jupiter.

We won't see any major opening-up of outer planet options until and unless there are some revolutionary new propulsion technologies developed, I'm afraid...

-the other Doug

[Greg Hullender]

Actually a straight shot to Neptune might well take about the same time as a Venus-Earth-Earth gravitational assist to Jupiter, but the point is still reasonable.

Here's a slightly off-the wall thought: If the Space Station were actually useful as a platform for launching space probes, it might even make sense to send a bunch of probes up at once in an Ares V -- or even send probes and fuel separately -- assuming the Ares had the best cost per kg, of course. Heck, wouldn't it be nice if final assembly of space probes could be done in space so the assembled probe didn't have to be capable of standing the stress of launch? Just pack it in a box and let the space station crew put it together and send it on its way.

That might even make economic sense if we consider the space station to be a sunk cost -- that the money will be spent whether the crew do anything useful or not. Pity it's in such an awful orbit . . .

--Greg

[Jim from NSF.com]

That would be even more expensive. Redesigning spacecraft to be EVA compatible. The components still have to survive launch whether attached to a spacecraft or in another type of container. Rendezvousing the components with the ISS. hazardous fueling near the ISS