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Posted by: AscendingNode Oct 19 2007, 08:34 PM

So I've been thinking a lot lately about the BFR (Big Fantastic Rocket) being developed for the NASA manned spaceflight program, the Ares V. And I was wondering what sort of robotic missions it would make possible that before weren't possible.

At first I was thinking you could take something like the proposed Europa Explorer mission... which launches on a Delta IV heavy and orbits Europa.... and you could take that spacecraft and put it on a bigger rocket and do things like add extra radiation shielding so it could last longer or add extra propellant so that it could orbit Callisto, Ganymede, and Europa or something like that.

But that's just an improvement to an existing concept... what about things that no one has really thought about because they've been just thinking about things that could fit on existing rockets.

Sure, we could do things like putting an armada of spacecraft on one vehicle... but that would cost a lot of money for all of the separate power systems (RTG or Solar) and avionics... and that concept could be done anyway with multiple launches of existing rockets.

But with a BFR, we could do a Cassini style mission to Neptune (i.e. get to Neptune fast and carry enough propellant to stop from a high-speed encounter and do a tour). Or we could maybe carry enough shielding to orbit Io

So, what do y'all think? How would you fly a BFR?

Posted by: AscendingNode Oct 19 2007, 08:41 PM

BFT (Big Fantastic Telescope) on BFR

Nasawatch had a link to a youtube video of a concept for a big telescope on the Ares V

http://www.youtube.com/watch?v=LOsHAA000z0

Cool.

Posted by: The Messenger Oct 19 2007, 08:45 PM

I think a Saturn or Neptunian Flagship BFR mission would be a fantastic good test of the rocket before using it in manned space applications...and after. What a great way to earn a manned space rating while supporting a major science goal in the process!

A probe with this kind of oommph could reach Saturn in less than three years! In fact, it could be launched for Neptune and smash a couple of probes into Iapetus & Dione (for Cassini to observe) along the way - plug a New Horizons head on the beast=, and a mission could be only two years in the making!

Posted by: ugordan Oct 19 2007, 08:53 PM

@The Messenger: And then if the test flight of the rocket fails (doesn't have to be a spectacular failure, a mere couple of seconds too early upper stage cutoff would do) and several billion $$$ goes essentially down the drain?

Posted by: nprev Oct 19 2007, 11:20 PM

Brings up an interesting point, Gordan: Wonder how many unmanned test flights of Ares V are planned? IIRC, the Saturn V had five (Apollos 2 through 6). If a similar campaign is designed for Ares, then maybe we could do an interplanetary mission for the last test, assuming all the bugs are worked out...

EDIT: There were only two tests of the Saturn V: Apollos 4 & 6. What's amazing in my perspective from the current era is that 6 had many serious problems...so they figured them out, fixed them, and launched Apollo 8 less than eight months later... We need to figure out how to do things like that again.

Posted by: Juramike Oct 20 2007, 12:52 AM

Maybe we could use one of the later test flights to deliver and drop a few more MSL's down on Mars.

(Building a few more MSL's would also make it easier to justify adding the ChemCam back into the program - it would help dilute the cost.)

Using an Ares V vehicle to put serious hardware in Mars orbit would also provide proof of concept for a far-future manned Mars mission.

-Mike

Posted by: dvandorn Oct 20 2007, 06:55 AM

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.

They became incredibly reliable vehicles, but they were never cheap.



In some ways, we need to figure out how not to *ever* have to do things like that again. But first, let me say a couple of things:

The guys at Marshall, German and not, overdesigned the vehicle such that there was enough margin to absorb potentially fatal events and keep going. Not just keep the crew alive, but keep going.

Apollo 6 seemed to have a lot of unrelated problems when it flew, that's true. But they actually boiled down to only two basic problems with the first two stages of the rocket (with one simple wiring error compounding the problem), an easily-solved problem with the in-flight ignitor system for the S-IVB, and an easily identified and fixed problem with the materials used in the SLA adapter between the S-IVB and the CSM.

The Germans built those vehicles (especially the early ones) to telemeter so much information about themselves that the problems were rather easily diagnosed and fixes readily identified. So, while the problems seemed to be nearly insurmountable, the direct way in which the problems could be diagnosed led to a lot of confidence in the performance of the next rocket.

But...

The Apollo-Saturn development philosophy of "All-Up" testing was an *extremely* risky approach. It relied on the design and, moreso, the engineering philosophy upon which the Saturn was based being *so* well done that you just had to have confidence based on the engineering. Period. It's true that independent testing of the stages incrementally would have taken too much time (and incidentally cost more money) -- but in Mueller's original concept, he was willing to man a Saturn V after only a single successful test flight.

Saturn V had a magnificent flight record, mostly due to the margin built into all of its systems by those methodical Germans. But even after the deadline had been met and the time pressure was off, we nearly lost a crew when a malfunctioning engine came within about one second of vibrating itself out of the thrust assembly and tearing into the tankage above.

The problem with a huge and expensive launcher like a Saturn V or an Ares V is that they will always be too expensive to test a little bit at a time, and so will have to be over-engineered. Problem is, aerospace engineering these days seems to be all about doing as much as you can within your power/mass envelope, to cut your margins as slim as you possibly can and still get away with it. So I have doubts that the Ares V will be as immensely successful as its predecessor.

But I have no doubts that the all-up concept, carried over from Apollo to the Shuttle, will continue to prevail and that NASA, in its arrogance, will likely plan to man the Ares I and place Orion equipment for actual manned flights on the Ares V -- both after one successful test flight.

-the other Doug

Posted by: Paolo Oct 20 2007, 07:03 AM

I don't like the idea of flying planetary missions on large, expensive launchers like the Ares V (or the Saturn V if you like). The size of the spacecraft and the scale of its mission would probably be such to make it extremely expensive (à la Voyager Mars lander or JIMO), which would in turn make it unlikely to be ever approved.

Posted by: Jim from NSF.com Oct 20 2007, 12:48 PM

I would agree. Cost is proportional to weight

Posted by: djellison Oct 20 2007, 12:54 PM

Sorry - I've got to pick you up on that. 'a few more MSL's' is the same as saying 'a few more billion dollars'. Given that space science has about..ohh..12 cents to spare - 'a few more MSL's' on one LV is sci-fi.

Doug

Posted by: Jim from NSF.com Oct 20 2007, 12:59 PM

1st Ares V has no upperstage, 2nd flight is fullup with LSAM

Posted by: algorimancer Oct 21 2007, 02:37 PM

Of course, the Shuttle didn't have any test flights (other than approach & landing on Enterprise). They flew the prototype manned.

Posted by: nprev Oct 21 2007, 03:29 PM

Great point...dammit! I don't know what the man-rated certification process entails, but obviously unmanned test flights are not a hardline prerequisite.

Posted by: dvandorn Oct 21 2007, 04:48 PM

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.

But the Shuttle is its own launch vehicle in some ways -- the main engines are integral to the manned vehicle. So you cannot actually fly any portion of a Shuttle stack unless the orbiter is manned.

So, the Shuttle flew for the first time (and has always flown) with "exception waiver" documents. The basic approach is that there are some issues, inherent in the design of the vehicle, which render it potentially unsafe -- the location of the orbiter in the stack and the inability to shut down the solid rocket boosters once ignited, among other things -- which make the vehicle impossible to man-rate. So the Shuttle flies, every single time, with signed waivers which state that the program managers and crew are willing to undertake the risks associated with the items that cannot be man-rated.

In that way, the Shuttle has never actually been man-rated.

The Ares I approach will also require a Level One waiver for the use of a solid rocket booster as its first stage, for the same reason the Shuttle requires the same waiver -- the motor, once ignited, cannot be shut down. And, in at least that one aspect, it, too, will never actually achieve the status of man-rated.

-the other Doug

Posted by: Jim from NSF.com Oct 21 2007, 05:39 PM

The 1st four mission were categorized as test missions

Posted by: Jim from NSF.com Oct 21 2007, 05:42 PM

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

Posted by: nprev Oct 21 2007, 10:41 PM

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?

Posted by: David Oct 22 2007, 03:14 AM

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.

Posted by: AscendingNode Oct 22 2007, 04:12 AM

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?

Posted by: dvandorn Oct 22 2007, 04:13 AM

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

Posted by: David Oct 22 2007, 05:43 AM

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

Posted by: dvandorn Oct 22 2007, 07:47 AM

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

Posted by: ugordan Oct 22 2007, 08:21 AM

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.

Posted by: Jim from NSF.com Oct 22 2007, 11:28 AM

The RS-68 is throttleable

Posted by: Jim from NSF.com Oct 22 2007, 11:31 AM

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

Posted by: Jim from NSF.com Oct 22 2007, 11:33 AM

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

Posted by: dvandorn Oct 22 2007, 03:19 PM

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

Posted by: dvandorn Oct 22 2007, 03:23 PM

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

Posted by: Greg Hullender Oct 22 2007, 05:03 PM

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

Posted by: Jim from NSF.com Oct 22 2007, 05:36 PM

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

Posted by: Greg Hullender Oct 23 2007, 04:50 AM

No question it would be more expensive in the short term. As you say, nothing we have today was designed for it -- including the Space Station itself.

But is it inherently more expensive? If we had known 30 years ago that the goal was a permanent presence on the Moon, would we have done everything differently? If we had a more long-term focus, should we do it differently now?

For example:

Plan for two stations: one in LEO in the same plane as the moon's orbit and the other at the L1 point, tethered to the moon with a long cable.

Plan for three kinds of craft: Ares from surface to LEO, but a special reusable shuttle to go between LEO and L1, and yet another reusable, single-stage vehicle to go between L1 and the surface of the moon.

Send hydrogen fuel up from the Earth, but make O2 on the moon and send it up the tether. This last bit is critical, of course, since the O2 mass is 8 times the H2 mass.

Since this LEO station would be in the plane of the ecliptic, it would be a reasonable place to launch unmanned probes as well. As you say, they'd have to get up there in one piece somehow, but there would be plenty of time to fix anything that wasn't too major before sending them off. Given a large enough station, much of the work could be done inside -- not with EVA.

Yes, the cost would be fabulous. Maybe a good fraction of the 1/2-trillion we've spent on the Iraq war so far. But if we're trying to think of clever ways to use the lift capacity of the Ares V to benefit unmanned space flight, I like this better than just spending more to launch things the way we always have.

--Greg

Posted by: Jim from NSF.com Oct 23 2007, 11:45 AM

Still not worth it.
Not EVA? Still weightlessness would still cause problems. Do we assemble submarines underwater or ships while they are at sea. No, they are assembled in a drydock where they are not influenced by the "water" and where the labor is there for only 8 hours and doesn't have to be housed and fed.

No need for an intermediate step, just launch the probe and send it directly to its destination.

A station that big is a waste and not going to happen for decades. The drydock in space is still Scifi

Just as RLV's, at current world launch rates, are not cost effective, neither are reusable lunar shuttles and landers. 2-3 missions a year to the moon are not enough to justify extensive infrastructure.

We are stuck with ELV's for a while

Posted by: nprev Oct 23 2007, 02:20 PM

Hate to say it, but I personally think that UMSF missions launched off-Earth will only be feasible once a suitable industrial complex is established on the Moon...and that's a completely different can of worms which I will leave safely unopened for now...

Posted by: Jim from NSF.com Oct 23 2007, 06:14 PM

I take it that you meant RLV in this case. The issue isn't maintenance costs. It is the development costs to reduce the maintenance requirements. A true RLV would be very costly to be developed right. The huge costs still have to be "bought down" by high flight rates and there isn't enough demand for flights.

Posted by: nprev Oct 23 2007, 06:32 PM

That's an excellent point, Jim. Although it does seem as if demand for flights is increasing, apparently it hasn't reached the point where an RLV could pay its own way yet...if ever? An analysis of historical & projected demand would be very interesting.

Posted by: djellison Nov 22 2007, 02:54 PM

Two posts regarding a politician removed. Politics (and thus Politicians) are not allowed at UMSF. Fact.

Doug