NASA reveals new “heavy-lift� SLS rocket

[thorfinn]

Didn't they understand that putting people, not Kerbals, on top of a rocket that has solid motors anywhere outside the LES is a BAD IDEA? .....

[Tiberion]

( I posted this in another thread, though it means more here )

Sorry if this has been said before but sadly, this is not going to do anything but make jobs. Not much science will be done, but the senators and stuff will be realllllyyyy happy since their districts get special funds and shit from the government since they get to build it. It will cost many billions of dollars - which could by a few thousands of trips on SpaceX's ships, and it will be done in 4, 5 years while SpaceX could launch any day. This is really heartbreaking, NASA should be doing what they want to do- not what will make some government employees happy. All of the 'man to mars' or whatever you are hearing from this is just to get more money to be poured in to someone's pockets. :c

Anyways, here is a video of all of the shuttle flights to make everyone happy again!

Also, I accept any info regarding if my statement is false or I'm just being pessimistic :3 More space missions are better than none!

Its true that 'science' doesn't seem too important to the current admin. - but the closer we get to getting some of these built and throwing things into to space, the more likely we are to accidentally step in some science and bring it home with us.

[sneakeypete]

On that point, what is with the focus on Single rocket to the moon/mars etc?

Why can't NASA just use say, one of the regular heavy lift rockets to assemble a craft in orbit (say at the ISS) then use a soyuz (or spacex if they get that far) to ferry the astronaughts up. Heck, you could even make the craft a reusable one minus the crew reentry pod..

Wait, why don't we just send the ISS to mars?

[DoctorEvo]

Actually, it's quite a bit different. This is closer to an SRB-equipped version of the Saturn INT-20 (http://astronautix.com/lvs/satint20.htm) or the Saturn 2SL/120' SRB variant of the Saturn INT-18 (http://astronautix.com/lvs/satint18.htm) design studies. In terms of size, it's closer to the INT-20, but designwise, it's more like the INT-18, using hydrogen in the first stage instead of kerosene.

I'd say that there's more than enough disparity here to say that this rocket is NOT a member of the Saturn family whatsoever. It's pretty solidly Shuttle-derived. The resemblance is purely aesthetic.

Really, the only part that's directly comparable to any of the Saturn designs would be the upper stage, which looks to be very close to the S-IVB, except it'd have to be scaled up, since the Apollo CSM had a diameter of 3.9 meters, while the Orion CSM that this is designed for has a diameter of 5 meters.

You know that's just an adapter, right? The S-IVB itself was entirely cylindrical and 20 feet around at both ends. With a different adapter, an S-IVB would mate just fine to Orion without scaling.

Besides, the EDS is shuttle-ET based anyways, so I think it's safe to assume it'll be considerably wider and more squat than S-IVB.

I think the biggest reason it 'looks' like a Saturn V is that it has similar roll patterns on it...

Exactly.

And when they run out after seven launches, they're going to have to start buying new ones. Simply put, there's a bunch of good reasons *not* to use the SSME in anything that's not reusable; that's just the biggest one. (How about having to do a Flight Readiness Firing pre-launch 'engine test' before *every flight*?)

Well that's kinda fallacious... the same is true of pretty much all expendable engines as well. Viking is the only liquid engine I'm aware of that is regularly flown without being test-fired first. Otherwise, you're gonna have to turn to solid-fuelled engines if you wanna have that sort of launch flexibility.

The cost issue is clearly by far the most significant. It does seem rather silly to use SSMEs in an expendable manner.

But will it be the new Constellation/Venturestar/NASP/...?

Probably.

Why are they using the RS-25's for the first stage? Better off just modifying an RS-68 to make it man rated. Twice the thrust with half the complexity. Could probably ditch the SRB's too if they did...

Performance. RS-68s use a wasteful gas-generator cycle, similar to that of the Apollo-era J-2s. They also have a lower thrust:weight ratio than both the SSMEs and the J-2, which in my opinion is inexcusable for a simple gas-generator engine, especially considering how recently the RS-68 was designed. All this amounts to a sizable performance hit in terms of payload-to-orbit. Omitting the boosters would be out of the question. The fact that you could get away with using only three of them is peanuts when you consider that three of them would still weigh almost double that of five SSMEs.

All said, though, it might be worth taking the performance hit just for the sake of cost savings. First stages are big and expensive, and looking for cheaper, heavier, less-efficient solutions (for instance, SRBs) is a very reasonable thing to do (unlike on upper stages, where the costs of excess weight trickles down to lower stages as well).

I agree, although man-rating the RS-68 is far from a trivial operation. There were (last time I checked) 200 changes that need to be made in order to leave the RS-68 suitable for man-rating.

Beauracracy. That's all I have to say.

Incidentally, can anyone explain to me the difference between the SLS and the Areas V? As far as I can see the difference is entirely political . . .

They're both Shuttle-derived, but there are a few significant differences. For one thing, unlike SLS, Ares V was not man-rated. It was expected to be used in tandem with the man-rated Ares I, a much smaller and very distinct (SRB-derived) rocket. Ares V was two stages (plus boosters) only, whereas SLS is planned to be single-stage plus boosters for most low-orbit missions, and two-stage only for higher or heavier missions.

But yes, in the two-stage configuration, SLS is very similar to Ares V, and the whole thing is rife with politics.

It seemed petty when they switched away from Bush’s returning to the moon. I think Obama has changed the long term goal to Mars instead.

Huh? I don't think so. Constellation had a faint inkling of possible interplanetary missions in the distant future that *might* be possible but probably won't happen, while SLS doesn't seem to have any notion of leaving Earth orbit at all.

The biggest problem I have with that move is it feels more like an accomplishment for the sake of accomplishing. No doubt the whole space race started with those ideals, but I want long term-sustained exploration where the main goal is for the benefit of scientific study, and not just to go there for a few missions and never return. Permanent moon exploration/occupancy is the next logical step from having a permanently manned space station.

The problem with that is that robotic space exploration can already do everything manned exploration can and more. If your goal is only science, then manned exploration is obsolete.

Didn't they understand that putting people, not Kerbals, on top of a rocket that has solid motors anywhere outside the LES is a BAD IDEA? .....

Why? The LES doesn't care what's behind it. It'll pull you away from boosters or liquids or a silo of irradiated nitroglycerin all the same.

SRBs are not the problem. A missing exit-strategy is the problem.

On that point, what is with the focus on Single rocket to the moon/mars etc?

Why can't NASA just use say, one of the regular heavy lift rockets to assemble a craft in orbit (say at the ISS) then use a soyuz (or spacex if they get that far) to ferry the astronaughts up. Heck, you could even make the craft a reusable one minus the crew reentry pod..

Because Earth-Orbit Rendezvous is just a crutch for when you don't have a rocket big enough to do the job in one shot.

Wait, why don't we just send the ISS to mars?

Oh jeez.

I don't think even the ISS has enough consumables for the whole trip there and back. Maybe with a single crewman.

Anyways, I think there's one thing above all that needs to be said about this rocket:

[shadow=red,left]IT NEEDS MORE BOOSTERS.[/shadow]

[sneakeypete]

Because Earth-Orbit Rendezvous is just a crutch for when you don't have a rocket big enough to do the job in one shot.

Which we don't, and I still wouldn't yet put good money on this rocket ever getting to the pad (but would be pleasantly surprised if it did)

And, sure, a single large rocket, rocket vs rocket, might be the way to go, but I think once you take all the bureaucracy and politics into it (and, unfortunately, those are things that always need to be taken into account), maybe not

Oh jeez.

I don't think even the ISS has enough consumables for the whole trip there and back. Maybe with a single crewman.

Oh well just tether up a few of those resupply pods to it, add some boosters and away she goes ;P

[icefire]

Would you really need all the science modules the ISS has to go to mars? Sounds like a whole lot of dead weight to me...

[Tiberion]

We could wait until the Chinese get theirs up there, and then 'borrow it'

[UmbralRaptor]

Probably.

;_;

I'm starting to wonder if I should fear NASA's unmanned activities winding down over the next decade or three?

[Octo Shock]

I honestly think its half economy/jobs and half pure necesedy. >

[DoctorEvo]

Which we don't, and I still wouldn't yet put good money on this rocket ever getting to the pad (but would be pleasantly surprised if it did)

And, sure, a single large rocket, rocket vs rocket, might be the way to go, but I think once you take all the bureaucracy and politics into it (and, unfortunately, those are things that always need to be taken into account), maybe not

Well if you can't pull it together enough to start building the proper hardware, you can bet you aren't going to pull off an interplanetary exploration program.

Oh well just tether up a few of those resupply pods to it, add some boosters and away she goes ;P

Boosters?

I'm sold.

[sneakeypete]

Would you really need all the science modules the ISS has to go to mars? Sounds like a whole lot of dead weight to me...

I wasn't being particularly serious with that comment

[rdfox]

Doc, I will point out that EOR may have certain cost advantages, too, if the price-per-mass of the smaller boosters is enough lower to compensate for the cost of flying multiple launches and flying assembly missions, particularly as economies of scale kick in on the production side. (Part of the reason the Saturn V was so expensive was that there was so little demand to spread out its development cost over, while smaller boosters can be sold to many more customers and thus spread their sunk costs out a great deal more, after all.)

Add in the cruel nature of the rocket equation, and there does come a time when on-orbit assembly of the spacecraft begins to make sense as you pass the point of diminishing returns on your heavy-lifter. (I expect that's going to turn out to be somewhere in the range of 100-200 metric tons to LEO payload capacity, unless there's some radical new development that allows for some vast increase in heavy-lift efficiency--perhaps once fusion gets working well enough to allow a nuclear *fusion* thermal rocket, as opposed to a fission-thermal rocket.)

[DoctorEvo]

Doc, I will point out that EOR may have certain cost advantages, too, if the price-per-mass of the smaller boosters is enough lower to compensate for the cost of flying multiple launches and flying assembly missions, particularly as economies of scale kick in on the production side. (Part of the reason the Saturn V was so expensive was that there was so little demand to spread out its development cost over, while smaller boosters can be sold to many more customers and thus spread their sunk costs out a great deal more, after all.)

That'd be just fine, except the opposite is almost universally true - larger rockets achieve a much lower cost-per-kg to orbit.

Add in the cruel nature of the rocket equation, and there does come a time when on-orbit assembly of the spacecraft begins to make sense as you pass the point of diminishing returns on your heavy-lifter. (I expect that's going to turn out to be somewhere in the range of 100-200 metric tons to LEO payload capacity, unless there's some radical new development that allows for some vast increase in heavy-lift efficiency--perhaps once fusion gets working well enough to allow a nuclear *fusion* thermal rocket, as opposed to a fission-thermal rocket.)

Well between launching a rocket that's 5 times larger once or launching five smaller rockets into the same orbit, the bigger rocket is almost always cheaper. The only reason to use multiple smaller rockets over one bigger one is if the payloads need to be placed into their own orbits.

[Johno]

That'd be just fine, except the opposite is almost universally true - larger rockets achieve a much lower cost-per-kg to orbit.

. . . unless it's manufactured to specs provided by NASA, in which they carefully design the program to avoid economies of scale. In which case a big rocket is also hideously expensive.

[sneakeypete]

Um, can you point out to me the 100t+ to orbit large rockets which actually have realized the cheap cost per kg?

Like i said, politics and bureaucracy gets in the way of engineering all the time, gotta learn to deal with it though.

[rdfox]

That'd be just fine, except the opposite is almost universally true - larger rockets achieve a much lower cost-per-kg to orbit.

There does come a point of diminishing returns--look at Wiki's list of launch systems and their cost-per-kilo to LEO. (http://en.wikipedia.org/wiki/Comparison_of_orbital_launch_systems) For example, RSA's Strela (basically, a UR-100!) can put 1700 kg into LEO for five million euros, so about $10 million; the Saturn V could put 118,000 kg into LEO, but adjusted for inflation, would have cost about $1.1 billion. For the same price, you could launch 110 Strelas and put 187,000 kg into LEO. I expect that there's a happy medium somewhere in between that'd cost less than either, but it's still interesting.

Well between launching a rocket that's 5 times larger once or launching five smaller rockets into the same orbit, the bigger rocket is almost always cheaper. The only reason to use multiple smaller rockets over one bigger one is if the payloads need to be placed into their own orbits.

See above. In that situation, there'd be no reason to use the Saturn unless you had some very heavy component that needed to be put into orbit in a single piece--unless you wanted to avoid flying assembly missions, so that you could assemble and test the entire vehicle on the ground rather than having to do EVAs to make the final connections.

[DoctorEvo]

. . . unless it's manufactured to specs provided by NASA, in which they carefully design the program to avoid economies of scale. In which case a big rocket is also hideously expensive.

Well, bluntly put, yes, that can be the case.

Um, can you point out to me the 100t+ to orbit large rockets which actually have realized the cheap cost per kg?

Like i said, politics and bureaucracy gets in the way of engineering all the time, gotta learn to deal with it though.

100t+? There are all of TWO rockets with that kind of payload, and of them, Energia was the closest - and it was only ever launched twice, before political turmoil caused its cancellation. The N1 was close, and it WAS actually a fairly inexpensive rocket given its size.

But if you choose a more reasonable and diverse criterion - say, 25 or 50 tons - you start to see some very successful rockets with excellent costs-per-kg. If you can use reasonable building practices and avoid building above your means, you CAN achieve fairly good economics by simply up-scaling.

There does come a point of diminishing returns--look at Wiki's list of launch systems and their cost-per-kilo to LEO. (http://en.wikipedia.org/wiki/Comparison_of_orbital_launch_systems) For example, RSA's Strela (basically, a UR-100!) can put 1700 kg into LEO for five million euros, so about $10 million; the Saturn V could put 118,000 kg into LEO, but adjusted for inflation, would have cost about $1.1 billion. For the same price, you could launch 110 Strelas and put 187,000 kg into LEO. I expect that there's a happy medium somewhere in between that'd cost less than either, but it's still interesting.

Well, we've been over the reasons Saturn was expensive before. Currently, the 'happy medium' you're talking about seems to lie in the neighborhood of 50 tons (with Proton and soon the Falcon Heavy leading the pack), but it WILL grow as the industry grows.

See above. In that situation, there'd be no reason to use the Saturn unless you had some very heavy component that needed to be put into orbit in a single piece--unless you wanted to avoid flying assembly missions, so that you could assemble and test the entire vehicle on the ground rather than having to do EVAs to make the final connections.

Yes, well, there is the factor of how a one-piece spacecraft will probably weigh much less than a modular design assembled from 50 components, but I'm ignoring that for now because it's a little hard to estimate HOW much heavier modular designs would be.

I do like the EOR/LOR scheme you proposed before, though - where the ultimate plan is to reuse already-launched hardware several times without recovery. That would most likely have a major impact on the average costs-per-mission, especially for low-mass-fraction components.

[sneakeypete]

100t+? There are all of TWO rockets with that kind of payload, and of them, Energia was the closest - and it was only ever launched twice, before political turmoil caused its cancellation. The N1 was close, and it WAS actually a fairly inexpensive rocket given its size.

Well that's what we're talking about here, what i've been reading are saying 100-130ish for the SLS.

Yes, if you choose 25-50 it becomes quite economical, due to the fact there is demand for that payload. However again, we were never talking about that.

My point is, why the SLS instead of say, two falcon heavies?

[icefire]

Politics

[DoctorEvo]

Well that's what we're talking about here, what i've been reading are saying 100-130ish for the SLS.

Yes, if you choose 25-50 it becomes quite economical, due to the fact there is demand for that payload. However again, we were never talking about that.

My point is, why the SLS instead of say, two falcon heavies?

Right NOW? Well I think the BIGGEST reason is because they've already put in so much into Ares and they don't want all that development to go to waste, and because a single-launch mission is much easier to coordinate. It is fairly unlikely the SLS will be very cost-effective unless they make some major changes to it.

However, I'm frankly kind of disappointed they didn't put their big dreams on hold for a while and go forward with the relatively modest Ares I, though. Even if it's just a small space taxi, it'd be enough to lift much of our dependence on the Russians for the ISS program, and it actually has the potential to be very cost effective.

[Johno]

I agree with that, DrEvo. In fact, it was the SRBs that were probably the most well-developed component of the Shuttle architecture, and they'd got the reusability of those down to a fine art. If they'd have forged ahead, It wouldn't have been hard to imagine the price of launching an American crew into space dropping below that of launching a Soyuz, especially if they'd have gone ahead with the re-usable Orion concept.

I know that I pointed to mass-production as being a better cost reduction method than reusability, but you can get some real benefits if you can make mass-produced parts re-usable, especially if you don't sacrifice ease of manufacture for it. In the Ares 1 system (as originally envisaged), the only parts of the system that you'd throw away would have been the relatively cheap upper stage and the expendable heat shield module.

[rdfox]

I'm very frustrated that Ares I isn't going to be completed; the system is extremely simple and could probably be flying inside of two years. However, I do recall that NASA determined, much to their chagrin, that it was going to have a payload to LEO a couple tons *less* than what the Orion MPCV would weigh, thus kind of making it superfluous, since it wouldn't be able to lift the vehicle it was designed for. (Still, if I were the contractor, I'd complete the development on my own to market as a commercial launcher; there's a lot of light payloads that would easily be within its capabilities, and the use of the RSRM first stage would probably let me get the price *way* down.)

Interestingly, remember how everyone said that the SLS looked sort of like strapping SRBs to an S-V? Well, it turns out that the version everyone was seeing was the initial version, with 60-ton payload capacity and *no* upper stage, just the core stage and boosters. (I thought that I was seeing an upper stage beneath the spacecraft, but it turns out that no, there's just an adapter there.) The upper stage in the 'evolved' version will be the same diameter as the core stage, as tall as the spacecraft and adapter, and will increase payload to LEO to 130 tons. The full Evolved SLS Cargo stack, with payload and fairing, would be 400 feet tall, requiring the VAB's doors to open all the way for the first time since 1975, with a mere 10 feet clearance under the doors at rollout!

If NASA switches to RS-68s or other expendable engines for the first stage, I could see the Initial SLS being made cost-effective as a heavy-lifter, but I suspect that the Evolved SLS will be limited to government use, since there's very little in the way of missions for a vehicle designed to put locomotives into orbit, except for putting up large space stations in a single launch, or launching spacecraft for exploring space *outside* earth orbit. And since Hilton doesn't have plans to put up an orbital hotel in the near future, and He-3 fusion (which would make commercial exploitation of the Moon attractive) seems like it'll be a pipe dream, at least within *our* lifetimes...

[DoctorEvo]

I agree with that, DrEvo. In fact, it was the SRBs that were probably the most well-developed component of the Shuttle architecture, and they'd got the reusability of those down to a fine art.

Well...

But given they managed to get 20 or so flights on average out of SRB segments on average, I think there are some significant savings to be had in that area.

If they'd have forged ahead, It wouldn't have been hard to imagine the price of launching an American crew into space dropping below that of launching a Soyuz, especially if they'd have gone ahead with the re-usable Orion concept.

Maybe. Ares I and Orion both are far larger and heavier than Soyuz, being more closely-comparable to a Saturn I/Apollo in terms of scale. Thus it is probable that Ares I launches would remain somewhat more expensive than Soyuz launches, though probably with a much lower cost-per-kg on cargo missions, should it ever be used as such.

I know that I pointed to mass-production as being a better cost reduction method than reusability, but you can get some real benefits if you can make mass-produced parts re-usable, especially if you don't sacrifice ease of manufacture for it. In the Ares 1 system (as originally envisaged), the only parts of the system that you'd throw away would have been the relatively cheap upper stage and the expendable heat shield module.

Well development costs for reusable parts are slightly higher, purchase costs are substantially higher, but you get to use them for what would normally consume several expendable counterparts. For instance, let's say a Shuttle SRB costs about three times that of an equivalent expendable booster, but you get to reuse it about 20 times. Worth it, right? Unfortunately, it isn't THAT simple, as the costs of recovery and refurbishment and reloading are actually quite significant, but the potential for massive cost savings is there.

I'm very frustrated that Ares I isn't going to be completed; the system is extremely simple and could probably be flying inside of two years.

Two years? Seems pretty tight for NASA...

But yeah, as far as the contractors go, they could easily have everything ready to go by then.

However, I do recall that NASA determined, much to their chagrin, that it was going to have a payload to LEO a couple tons *less* than what the Orion MPCV would weigh, thus kind of making it superfluous, since it wouldn't be able to lift the vehicle it was designed for.

How did that happen? Did Orion turn out heavier than they initially planned?

Anyways, I can't see it being a terribly difficult thing to fix, since the second stage is all-new anyways and could probably be stretched to make up for it. (After all, it WAS stretched and contracted several times early on in the design process...)

(Still, if I were the contractor, I'd complete the development on my own to market as a commercial launcher; there's a lot of light payloads that would easily be within its capabilities, and the use of the RSRM first stage would probably let me get the price *way* down.)

Funny you should mention that... ATK isn't one to pass up such an opportunity: http://en.wikipedia.org/wiki/Liberty_(rocket)

Unfortunately, they didn't win a CCDev contract, and are a little pressed for funding now...

Interestingly, remember how everyone said that the SLS looked sort of like strapping SRBs to an S-V? Well, it turns out that the version everyone was seeing was the initial version, with 60-ton payload capacity and *no* upper stage, just the core stage and boosters. (I thought that I was seeing an upper stage beneath the spacecraft, but it turns out that no, there's just an adapter there.) The upper stage in the 'evolved' version will be the same diameter as the core stage, as tall as the spacecraft and adapter, and will increase payload to LEO to 130 tons.

Yep, I mentioned that.

If NASA switches to RS-68s or other expendable engines for the first stage, I could see the Initial SLS being made cost-effective as a heavy-lifter, but I suspect that the Evolved SLS will be limited to government use, since there's very little in the way of missions for a vehicle designed to put locomotives into orbit, except for putting up large space stations in a single launch, or launching spacecraft for exploring space *outside* earth orbit.

Well I, for one, am in FULL support of the development of an inter-maria high-speed-rail network on the Moon.

Nah, but really, I do feel that as the industry matures, costs will come down and the market will grow. It will be slow, but it will happen.

[Sbowyer28]

No offence but i probably could build a better SAS ill put it on youtube if i have time to build it.

[GroundHOG2010]

Well at least they named it right for idiots, Space Launch System (SLS)