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Moonshot, CEV Modifications

ScuttleMonkey posted more than 7 years ago | from the falling-back-on-pre-1970-tech-is-always-the-answer dept.

Space 108

DarkNemesis618 writes "In the latest round of budget cuts, NASA introduced plans to modify the CEV for the planned Moon landing in 2018. The original plan called for an engine used on the space shuttle to be modified for the CEV. The new plan is to use an updated J-2 engine. The J-2 engine was first used on the Saturn V rocket which took the Apollo astronauts to the moon in the late 60's early 70's. It is not expected to save any money in the near-term, but in the far term, it should be a cost saver since the technology already exists and is proven. In the 10 Apollo launches aboard the Saturn V rocket, there were no problems with the launch vehicle."

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Newsflash - The Whitehouse cancels Mars mission! (-1, Offtopic)

Anonymous Coward | more than 7 years ago | (#14619856)

See the official press release here [whitehouse.com] .

Let's see... (3, Interesting)

Jafafa Hots (580169) | more than 7 years ago | (#14619880)

Modify a less-efficient, 40 year old design that hasn't been produced in several decades, or modify a more-efficient currently-used design. Choose the former because it "already exists?"

What am I not getting here?

Re:Let's see... (2, Insightful)

2.7182 (819680) | more than 7 years ago | (#14619927)

Here's the thing though: It worked 10 times. So what ? The space shuttle worked safely 24 times before it had a problem.

BTW there are 2 or so Saturn V still lying around to use- see here [wikipedia.org]

Re:Let's see... (3, Insightful)

SnowZero (92219) | more than 7 years ago | (#14620107)

The shuttle engine is not currently capable of in-air ignition, while the J-2 engine did exactly that for Apollo. The shuttle engine would thus have to be modified, while the J-2 engine would not. So it's more like 10 times vs 0.

P.S. This is pretty clearly written in the article.

Re:Let's see... (1)

2.7182 (819680) | more than 7 years ago | (#14620368)

That's not my point. What I meant is that just because it worked 10 times doesn't mean it is "proven". Ten is a small number of trials. I am not saying the Shuttle engines should be used.

Re:Let's see... (2, Informative)

AKAImBatman (238306) | more than 7 years ago | (#14620756)

The Saturn 1B flew an addition 10 flights on the J-2s, which was based on the Saturn 1 that flew 10 flights on the RL-10s, which was based on the Jupiter IRBM that flew about 17 flights. Each Saturn 1B had 1 J-2 while each Saturn V had 6 J-2 engines.

Or in other words, the J-2 engine has a long history and has proven itself highly reliable. Its reliability isn't really in question.

Re:Let's see... (1)

JWSmythe (446288) | more than 8 years ago | (#14623782)


    Unless we're talking about a shuttle engine that I'm not familiar with, the three main shuttle engines do burn in the air. They provide the balance and thrust from initial ignition until SRB seperation.

    The also continue burning into orbit. They don't stop burning until just before the external fuel tank is dropped.

    For easy proof, watch most launch videos. They usually show the engines fire up. You can usually see the entire launch vehicle tilt as soon as they're fired, before it leaves the ground.

    The three main engines have directed thrust, which gives the shuttle manuverability during liftoff. I don't believe the SRB's have any sort of directional control.

    While in orbit, the orbiter uses OMS thrusters, but I doubt that's what we're talking about here. Those have almost no thrust in compairson to the main engines or SRB's.

Re:Let's see... (1)

IAN (30) | more than 8 years ago | (#14624022)

Unless we're talking about a shuttle engine that I'm not familiar with, the three main shuttle engines do burn in the air.

They are ignited on the ground, and ignition depends on ground infrastructure. In-flight ignition would require engine modifications, and that is why the J-2 is an attractive alternative -- while its performance is lower, the engine is far simpler and specifically designed for in-flight startup.

Re:Let's see... (1, Informative)

Anonymous Coward | more than 7 years ago | (#14620204)

Yes, but the shuttle's engines only worked 19 times before one of them failed in flight. And only a fast thinking controller prevented a second engine from also shutting down, which was a very good since the Shuttle would of probably ended up in the middle of the Atlantic if a second SSME had gone down.

Re:Let's see... (1)

DerekLyons (302214) | more than 8 years ago | (#14622347)

BTW there are 2 or so Saturn V still lying around to use
Niether of those Saturn V's have their instrumentation unit, and niether of them is anywhere near in a condition to be launched.

Re:Let's see... (2, Insightful)

DisownedSky (905171) | more than 7 years ago | (#14619947)

The SSME is tricky beast. Converting a slightly more modern (30 year-old) but very large and complex lower stage engine vs. reviving an older upper stage design. They will re-design this engine somewhat, but they know the basic design works in the intended role.

Design reuse (1)

Beryllium Sphere(tm) (193358) | more than 7 years ago | (#14620088)

What you're not getting is the time, money and risk of debugging a new design.

The other point is that the SSME was never designed to be started at altitude.

Re:Let's see... (2, Insightful)

Anonymous Coward | more than 7 years ago | (#14620112)

Modify a less-efficient, 40 year old design that hasn't been produced in several decades, or modify a more-efficient currently-used design. Choose the former because it "already exists?"

It's not quite a simple as that.

True, the J-2 is older and less-efficient, but it's a much simpler, more reliable design than the SSME.

The SSME is much more intricate, tempermental, expensive and operates at much, much higher pressures than the J-2. The reliability of the SSME in the Shuttle is more a tribute to the army of inspectors employed by NASA than to its inherent design.

Personally, if I were trusting my life to a new rocket , I'd prefer to sacrifice a little ultimate efficiency for an engine that has reliabilty designed in, not inspected in.

Re:Let's see... (1)

joe_n_bloe (244407) | more than 8 years ago | (#14621744)

True, the J-2 is older and less-efficient, but it's a much simpler, more reliable design than the SSME.

The SSME is much more intricate, tempermental, expensive and operates at much, much higher pressures than the J-2. The reliability of the SSME in the Shuttle is more a tribute to the army of inspectors employed by NASA than to its inherent design.

Personally, if I were trusting my life to a new rocket , I'd prefer to sacrifice a little ultimate efficiency for an engine that has reliabilty designed in, not inspected in.


Not true - the SSME is more reliable than the J-2 and is in fact the most reliable booster engine ever built. There have never been any SSME in-flight failures and the SSME system has logged around 1 million seconds of hot fire time, the equivalent of over 600 3-engine missions.

But for a dose of reality, see: http://www.fotuva.org/feynman/challenger-appendix. html [fotuva.org]

Re:Let's see... (0)

Anonymous Coward | more than 8 years ago | (#14621942)

Not true - the SSME is more reliable than the J-2 and is in fact the most reliable booster engine ever built.

I'm not sure what you mean by "Not true".

I never claimed the SSME was "unreliable" per se. Just that it's larger, heavier, more complicated and operates at much higher pressures than the J-2.

I do claim that that reliability is due more to NASA inspectors than its inherent design; and if I had to trust my life to a machine, I'd rather have reliability designed in than inspected in.

I'll add that, to my knowledge, the SSME is not rated for in-flight starts or restarts, and the J-2 was.

Re:Let's see... (4, Informative)

Burdell (228580) | more than 7 years ago | (#14620123)

The SSME is higher efficiency in terms of thrust vs. mass. However, that isn't the only measure to be considered. Each SSME costs a lot more to build, because they were designed to be reused (IIRC the current plan is to not reuse the new vehicle's engines). The SSME is throttleable, but if that is not needed, it is an added complexity and expense. The J-2 was designed to be throw-away.

Also, there are some questions about the SSME for the new vehicle. The SSME would be used in upper stages that are lit in-flight. The SSME has only ever been lit sitting still, on the ground, at sea-level atmospheric pressure and temperature. The J-2 was used on upper stages of the Saturn V, so it is proven in that capacity.

Re:Let's see... (1)

Hynee (774168) | more than 8 years ago | (#14622980)

Yeah, the main reason cited for choosing a J-2 over the Space Shuttle Main Engine (SSME) is that the J-2 was always air lit, as the 2nd and 3rd stages of the Saturn V (the first stage used 5 F-1 engines).

However, I believe that the SSME is also lit in orbit, for the de-orbit burn, and possibly for orbit changing maneuvers (like when a space junk collision is likely). When lit in space, it uses fuel from 3 onboard fuel tanks rather than the big orange tank used for take off.

I guess the difference there is that no testing of the SSME has been done lighting it in the atmosphere.

Re:Let's see... (2, Informative)

Burdell (228580) | more than 8 years ago | (#14623223)

Nope, you are wrong. SSMEs are lit on the pad six seconds before liftoff. They burn for about 9 minutes and then shut down for the rest of the flight. The SSMEs are fueled by liquid hydrogen and liquid oxygen stored in the big orange external tank, which is discarded right after SSME shutdown (so the rest of the flight there isn't any fuel for the SSMEs). The next time an SSME would be lit is after removal from the orbiter, refit, and either at a test facility or at another launch.

Orbital maneuvering is done using the (wait for it) Orbital Maneuvering System, or OMS, engines. These are the two smaller "pods" on either side of the tail above the 3 SSMEs. The OMS (as well as the smaller RCS used for attitude control) engines use hypergolic fuels, nitrogen tetroxide and monomethylhydrazine.

Re:Let's see... (1)

Hynee (774168) | more than 8 years ago | (#14623335)

OK, and the OMS nozzles are the nozzles who's size is in between the big SSME bells and the small RCS nozzles, which are mostly hidden away. (Do I have this right?)

Re:Let's see... (1)

Burdell (228580) | more than 8 years ago | (#14623383)

Yes. Looking at the back end of the orbiter, the SSMEs are the three largest engines. Above them, on either side of the tail, are the two OMS engines. Then there are small RCS nozzles in various places around the nose and tail of the orbiter (IIRC there are 38 primary and 6 secondary RCS engines).

The SSMEs get you to orbit, the OMS change orbits and get you out of orbit, and the RCS point you where you want to look.

Re:Let's see... (1)

JWSmythe (446288) | more than 8 years ago | (#14623797)


    If I remember right:

    OMS = Orbital Manuvering System
    RCS = Reaction Control System

    RCS are almost always automatically firing to keep the attitude of the orbiter correct. OMS are used for manuvering, such as to roll over for re-entry or to manuver for satellite deployment or docking.

Re:Let's see... (1)

joe_n_bloe (244407) | more than 7 years ago | (#14621635)

Mainly, the SSME is incredibly complex and expensive ($40m). Even though it has vastly higher power density than the J-2, sometimes less is more.

I wish I could find parts counts for both the J-2 and SSME, but the good old days when I had all this info in Dead Tree Edition are long gone.

Not really a surprise (5, Informative)

AKAImBatman (238306) | more than 7 years ago | (#14619960)

Note that this isn't really a surprise to those who have been following the CEV development. The original plan called for a modification to the SSMEs for multiple restarts as the J-2 (the upper stage engine for the Saturn V) is no longer in production. However, there was a lot of discussion inside NASA that restarting production on the less powerful J-2 would be cheaper, faster, and easier than trying to modify the more powerful (but far more complex) SSME to do the job.

To give quick rundown on which engines are which:

SSME (Space Shuttle Main Engines) - LHOx Fuel - 1.8 MN
SRB (Solid Rocket Booster) - Solid Fuel - 14.7 MN
J-2 (2nd and 3rd stage Saturn V) - LHOx - 890 kN
F-1 (1st stage Saturn V) - Kerosine - 6.7 MN

The SSME and J-2 are directly comparable, and the SRB and F-1 are directly comparable.

Re:Not really a surprise (1)

LWATCDR (28044) | more than 7 years ago | (#14620090)

Which makes me wonder why not use the F1 instead of the SRB.

Re:Not really a surprise (2, Informative)

AKAImBatman (238306) | more than 7 years ago | (#14620280)

Did you see those differences in performance on those engines? The SSME is about twice as powerful as the J-2, but it also weighs twice as much. Thus it makes sense to use two J-2s. The SRBs OTOH, get over twice the power of the F-1 for far less weight. Since they're almost entirely fuel (not much engine, just light 'em up), they have an incredible thrust to weight ratio.

In addition, NASA has no infrastructure for Kerosine fuels, making the switch from the SRBs to the F-1 more difficult. They *do* have an infrastructure for LHOx fuels, so the change from the SSME to J-2 is a fairly easy one.

Re:Not really a surprise (3, Informative)

LWATCDR (28044) | more than 7 years ago | (#14620404)

"In addition, NASA has no infrastructure for Kerosene fuels,"
Atlas V?
Also what is the specific impulse for an F1 first stage VS an SRB?
Yes the SRB has more static thrust but I think the F1 is equal to it in specific impulse. Plus the F1 allows for an on pad shut down and is probably easier the vector than an SRB.
BTW the Specific impulse for the SRB is 268.8 For the F1 it is 304.8.

Using modern AlLi alloys for the tanks an F1 powered first stage might still be a good option. The real reason is cost. The SRBs are cheaper short term.

isn't thrust what's important? (1)

Quadraginta (902985) | more than 7 years ago | (#14620596)

Surely if the use is initial liftoff the important statistic is thrust to weight ratio. The question of efficiency -- which is what specific impulse measures -- seems rather secondary, unless I'm missing something. An ion engine, for example, would have a far greater specific impulse than either chemical engine, but since its thrust is so pathetic it couldn't get itself off the ground.

To put it in plebian terms, if you need to outrun the cops (i.e. achieve escape velocity), surely it's better to be driving this [dodge.com] instead of this [hybridcars.com] .

Re:isn't thrust what's important? (1)

LWATCDR (28044) | more than 7 years ago | (#14621018)

But you have to carry the fuel as well. The the thrust of the main engine must both lift it's self. the payload, and the fuel. Your example is an extreme example. For a liquid fuel launch vehicle the ideal thrust to weight ratio at launch is close to 1.1:1 any less and the thing is not going anywhere and more and you are not using the vehicle to it's maximum potential. You could put more fuel and go higher and faster or more payload to the same orbit. Yes you would also have to carry more fuel as well but you get the point.

Re:isn't thrust what's important? (1)

Quadraginta (902985) | more than 7 years ago | (#14621229)

But you have to carry the fuel as well.

Right. That's why I said thrust to weight ratio, i.e. thrust divided by weight. For the SRBs, it's enormous. Not so for the other engines. The fact that the SRBs don't squeeze as much energy out of their fuel seems rather beside the point. Fuel efficiency isn't the name of the game when you lift off, raw acceleration is -- yes?

That's why I suggested the comparison to the Dodge Viper vs the Toyota Prius. The Viper gets crappy gas mileage compared to the Prius, of course. But it has a much higher power-to-inertia ratio, so it can accelerate much harder (e.g. blast from 0 to 60 in far less time).

Re:isn't thrust what's important? (1)

AKAImBatman (238306) | more than 8 years ago | (#14622400)

That's why I said thrust to weight ratio, i.e. thrust divided by weight. For the SRBs, it's enormous.

Just some numbers to help you out:

SRB Liftoff: 14,700 kN / (590,000 kg * 9.807) * 1000 = 2.5:1 ratio
SI-C Liftoff: 33,400 kN / (2,280,000 kg * 9.807) * 1000 = 1.5:1 ratio

Of course, there's a huge curve in thrust-to-weight between the full and empty rockets (with the S-IC actually coming out ahead at empty), but I'm willing to bet that the plotted curves would show the overall power output of the SRB to be far superior. (If someone has too much time on their hands, they can plot these curves in excel by computing several data point between full and empty. Wikipedia and Astronautix both contain fuel burn rates for the rockets.)

Where do you think he gets this nonsense about a 1.1:1 ratio? A rocket would never make orbit with that kind of performance! (Putting aside the fact that it would topple over and blow up on launch.)

Re:isn't thrust what's important? (1)

LWATCDR (28044) | more than 8 years ago | (#14626359)

"Where do you think he gets this nonsense about a 1.1:1 ratio? A rocket would never make orbit with that kind of performance! (Putting aside the fact that it would topple over and blow up on launch.)"

Wow you don't really get it do you? That is at launch. As fuel is burned the rocket will get lighter.
Acceleration ISNOT important for a launch vehicle except during the transonic region of flight. At that time your drag goes way up and actually drops once you get to supersonic flight.. All acceleration does is stress the vehicle and add a lot of drag early in the flight.
As I said the IDEAL thrust to weight ratio is around 1.1 to 1 for a liquid fueled rocket under ideal condition. 1.5:1 is typical so you have a little extra thrust for vectoring and control. Modern rockets DO NOT need aerodynamic forces for flight control.

Re:isn't thrust what's important? (1)

AKAImBatman (238306) | more than 8 years ago | (#14627072)

Wow you don't really get it do you? That is at launch. As fuel is burned the rocket will get lighter.

No, everyone here but you gets it. If the rockets were launched in a vacuum, you'd be right. But for a launch, you're completely ignoring the factors of Gravity Drag [wikipedia.org] , Aerodynamic Drag [wikipedia.org] , and Engine Efficiency. Which is downright laughable since you mention the engine efficiencies as if they support your point!

You MUST get the rocket above the effects of aerodynamic drag as quickly as possible, otherwise you're going to be expending your rocket's energy against the atmosphere. You must also get your rocket the hell off the ground as fast as possible, otherwise you'll be wasting energy by fighting gravity. Remember, for every second of your burn, you're losing 9.8 meters per second per second of velocity. At a 1.5 or higher ratio, you'll gain your Delta-V far faster than gravity can rob you of it. At a 1.1 ratio, gravity will kill your fuel efficiency. Dead. From here [wikipedia.org] :
When applying delta-v against gravity to increase specific orbital energy, it is advantageous to spend delta-v at as high speed as possible, rather than spending some, being decelerated by gravity, then spending some more, or spending it at less than full capacity. Gravity drag can be described as the extra delta-v needed because of not being able to spend all the needed delta-v instantaneously.

This effect can be explained in two equivalent ways:

        * The specific energy gained per unit delta-v is equal to the speed, so spend the delta-v when the rocket is going fast; in the case of being decelerated by gravity this means as soon as possible.
        * It is wasteful to lift fuel unnecessarily: use it right away, and then the rocket does not have to lift it.


It isn't until orbital velocity that the 9.8 meters per second per second works in your favor by drawing you toward the earth, but with enough lateral velocity to miss it completely.

Modern rockets DO NOT need aerodynamic forces for flight control.

They do if they can't overcome their own weight. You've got a large tower being balanced only by the gimballing of its lower boosters. If you don't transmit enough force throughout the structure fast enough, its own weight WILL bring it down.

1.5:1 is typical so you have a little extra thrust for vectoring and control.

And here again, you say it, but it doesn't click. If you don't have enough thrust for vectoring and control, how exactly do you expect the vehicle to remain in the air?

Re:isn't thrust what's important? (0)

Anonymous Coward | more than 8 years ago | (#14623188)

must both lift it's self. the payload, and the fuel

"itself,".

For a liquid fuel launch vehicle the ideal thrust to weight ratio

"vehicle, the".

close to 1.1:1 any less and the thing

"1.1:1. Any less,".

not going anywhere and more and you are not

???

to it's maximum potential

"its".

You could put more fuel and go higher and faster or more payload to the same orbit.

"add more fuel", "or deliver more payload".

Re:Not really a surprise (2, Insightful)

AKAImBatman (238306) | more than 7 years ago | (#14620606)

"In addition, NASA has no infrastructure for Kerosene fuels,"

There have been a handful of Atlas V launches. Nothing near the scale of what the Shuttle flys today, and what the CEV *will* fly.

Yes the SRB has more static thrust but I think the F1 is equal to it in specific impulse.

Static thrust is what you want. The point of the F-1s and SRBs was to get the rocket off the pad, up to Max Q, and out of the thickest part of the atmosphere. From there the more efficient LHOx engines provide more than enough thrust to carry the weight into orbit. The plain and simple fact is that the F-1 is MUCH heavier, reducing the overall efficiency of the entire rocket. Thus the SSME/SRB combination will continue to be used for the liftoff phase. The J-2 will be used in orbit where its reliability and restart advantages make it a better choice than the SSME, and the F-1/SRB argument doesn't even enter.

Using modern AlLi alloys for the tanks an F1 powered first stage might still be a good option.

Then the program would be held up for years why they certify a new engine. That defeats the point of the entire CEV exercise. (i.e. Build an infrastructure quickly.)

The real reason is cost. The SRBs are cheaper short term.

The SRBs are always cheaper. Not to mention reused.

Re:Not really a surprise (2, Informative)

LWATCDR (28044) | more than 7 years ago | (#14621119)

"There have been a handful of Atlas V launches. Nothing near the scale of what the Shuttle flys today, and what the CEV *will* fly."
What are you talking about? The shuttle flew 12 times a year at it's peak? The CEV will fly maybe that many? The Atlas V is going to be used for commercial and military launches for how many years?
I also do not believe that the F1+Fuel is much heavier then an SRB. The difference in the specific impulse means close to 10% less fuel mass for the F1 than the SRB.
Without a complete study with more data then you or I have the choice of the SRB over an F1 is at best a guess.
I will say that Boeing did design a replacement for the SRB that used... The F1 for a fly back booster.

Re:Not really a surprise (2, Interesting)

AKAImBatman (238306) | more than 7 years ago | (#14621370)

What are you talking about? The shuttle flew 12 times a year at it's peak? The CEV will fly maybe that many?

And the Atlas V has flown only 7 times in the past 3.5 years it's been in operation. Plus it's not even NASA's rocket. They've flown it twice, with the other flights being entirely commercial. The future planned flights will be mostly military and will attempt to move the launch to Vandenberg.

I also do not believe that the F1+Fuel is much heavier then an SRB.

Saturn 1C Empty: 135,218 kg
SRBx2 Empty: 174,000 kg
Saturn 1C Fueled: 2,286,217 kg
SRBx2 Fueled: 1,180,000 kg

What a difference of a kiloton in mass between rockets, eh? :-P

In short, the SRBs weight half as much to get nearly the same performance as the 5 F-1s that the Saturn V did.

The difference in the specific impulse means close to 10% less fuel mass for the F1 than the SRB.

Wrong. You've got to be careful with those Isp figures. They're very misleading.

Re:Not really a surprise (2, Informative)

AJWM (19027) | more than 8 years ago | (#14621995)

Saturn 1C Empty: 135,218 kg
SRBx2 Empty: 174,000 kg
Saturn 1C Fueled: 2,286,217 kg
SRBx2 Fueled: 1,180,000 kg


That's not quite an apples-to-apples comparison. Initial thrust of the 2 SRBs is about 5 million pounds, of the S1C, about 7.5 million pounds. The Shuttle launch is also augmented by the thrust of the 3 SSMEs, and the whole thing puts about 65,000 pounds in orbit. The Saturn lower stages (S1C followed by SII) could put about 200,000 pounds in orbit.

The 2 SRBs don't have quite the same thrust as the 5 F-1s of the S1C, and don't have nearly the total impulse. The S1C stage engines burn for almost a minute longer than the SRBs.

Re:Not really a surprise (1)

AKAImBatman (238306) | more than 8 years ago | (#14622225)

Initial thrust of the 2 SRBs is about 5 million pounds

Where do you get 5 million pounds? I have 3.3 million pounds of force per SRB, giving a combined total of 6.6 million pounds of force, or 29.4 kN. That's pretty darn close to the 33.4 MN of the S-IC.

Shuttle launch is also augmented by the thrust of the 3 SSMEs

This is where we start getting into the fact that the Shuttle is just different. The total STS power on liftoff is OVER the standard 34.8 MN of all the engines combined (the SSMEs are overthrottled at liftoff), the acceleration curves are different, the F-1s need more fuel to compensate for lower thrust, the entire shuttle stack is lighter than the S-IC, so on and so forth.

The comparison is fair, but the two total designs aren't really 1:1 comparable.

the whole thing puts about 65,000 pounds in orbit.

The STS has a theoretical maximum of 137.8 metric tonnes to orbit. Of that, 109 metric tonnes is the orbiter itself. The maximum theoretical payload of the Saturn V is 118 metric tonnes to orbit, of which none of it is lost through integration with a vehicle.

The 2 SRBs don't have quite the same thrust as the 5 F-1s of the S1C, and don't have nearly the total impulse.

I'm not sure what you mean by "nearly the total impulse". The SRBs fired in conjunction with the SSMEs gives the shuttle a far greater efficiency than the Saturn V.

Re:Not really a surprise (2, Informative)

AJWM (19027) | more than 8 years ago | (#14623518)

Where do you get 5 million pounds? I have 3.3 million pounds of force per SRB, giving a combined total of 6.6 million pounds of force, or 29.4 kN. That's pretty darn close to the 33.4 MN of the S-IC.

I was thinking 2.3 million pounds per SRB and doubling it. I stand corrected. However, the SRBs propellant is shaped to gradually reduce thrust over time (to compensate for reducing weight of the stack and limit overall acceleration). The F-1s gain efficiency with altitude and at just before center-engine cutoff, the 5 are putting out about 9.3 million pounds thrust, dropping to about 7.4 million with 4 (1.85 million pounds thrust each).

the whole thing puts about 65,000 pounds in orbit.

The STS has a theoretical maximum of 137.8 metric tonnes to orbit. Of that, 109 metric tonnes is the orbiter itself.


You're right. My bad. That 65K number is the original design payload of the Shuttle (actual closer to 50K pounds). The Orbiter itself is a couple hundred thousand pounds which also makes orbit.

I'm not sure what you mean by "nearly the total impulse". The SRBs fired in conjunction with the SSMEs gives the shuttle a far greater efficiency than the Saturn V.

Total impulse -- thrust times time. Newton-seconds, if you like metric. "Efficiency" don't enter into it, without defining all your terms. If the Shuttle really had "a far greater efficiency than the Saturn V" (defining "efficiency" as "lift capacity"), it'd be able to put an Apollo CSM/LM combo (or equivalent mass) into trans-Lunar orbit, or a Skylab-equivalent into LEO. It can't do either, although arguably the Orbiter itself, with a Spacelab or Spacehab in the cargo bay, is nearly Skylab-equivalent. (Less roomy and shorter duration, though, although Skylab wasn't designed for reentry.)

Re:Not really a surprise (1)

AKAImBatman (238306) | more than 8 years ago | (#14623675)

Total impulse -- thrust times time. Newton-seconds, if you like metric

Gotcha. :-)

"Efficiency" don't enter into it, without defining all your terms. If the Shuttle really had "a far greater efficiency than the Saturn V" (defining "efficiency" as "lift capacity"), it'd be able to put an Apollo CSM/LM combo (or equivalent mass) into trans-Lunar orbit, or a Skylab-equivalent into LEO. It can't do either, although arguably the Orbiter itself, with a Spacelab or Spacehab in the cargo bay, is nearly Skylab-equivalent. (Less roomy and shorter duration, though, although Skylab wasn't designed for reentry.)

You said it yourself. The Space Shuttle's weight has to be taken into consideration of the final payload. Otherwise it looks like the vehicle is far less powerful than the Saturn V, which just isn't the case.

The Space Shuttle is lighter than the Saturn V, but can carry more cargo to orbit. It does this well, but is tied to ensuring that 109 metric tonnes of it is the orbiter itself. If the orbiter were removed from the equation (as the 125 tonne to orbit shuttle-derived HLV is doing), the shuttle could put up Skylab and a lot more.

However, the SRBs propellant is shaped to gradually reduce thrust over time (to compensate for reducing weight of the stack and limit overall acceleration).

Yep. The SRBs could be made to maintain maximum thrust throughout the flight, but doing so would probably result in critical Q. Damned powerful buggers, but also damned uncontrollable. :-/

The center engine on the SatV cuts out for the same reason, but at a later time. The Space Shuttle hits Max Q at about 1 minute into flight whereas the Saturn V hits it at 1 minute and 20 seconds.

The F-1s gain efficiency with altitude and at just before center-engine cutoff

As do the SRBs and SSMEs. In fact, pretty much all engines gain efficiency with altitude. The aerospike engine is an attempt to recoup some of that, but there still hasn't been an actual production design.

BTW, the F-1 has to fire longer for a variety of reasons, the two most important of which are:

1. It's heavier. The thrust from the S-IC has to carry its own weight (greater than a fully loaded Shuttle Stack!) plus the weight of the S-II and S-IVB stages. This gives the Shuttle stack a tremendous thrust to weight advantage over the Saturn V stack.

2. It has less overall thrust. The Space Shuttle has an incredible amount of thrust on lift-off. As I pointed out above, the shuttle hits Max Q significantly before the Saturn V. The Saturn V struggles a lot more than the shuttle, partly for want of more thrust, partly because it is so much heavier.

Re:Not really a surprise (0)

Anonymous Coward | more than 7 years ago | (#14621287)

yeah, sometimes I make up words too.

Re:Not really a surprise (3, Informative)

AJWM (19027) | more than 8 years ago | (#14621899)

The startup sequence for the F1 is hairy as all get out (taking about 7 seconds from "ignition sequence start" to full power). Furthermore, while it may be apocryphal, Harry Stine once told me that the ignition sequence was controlled by a patch-panel programmed computer and that the documentation for the patches was long since lost and those people that knew how to do it have mostly died off.

The F1 ignition sequence includes steps like pre-filling the inlet tubes with a hypergolic mix to actually light the thing, diverting some of the fuel (kerosene) to the hydraulic system for the gimbal actuators, a controlled chill of the lox plumbing without getting the kerosene plumbing too cold (don't want any frozen lumps in there), starting the gas generators to power the turbopumps, etc. -- not necessarily in that order. The SRB ignition sequence is basically just detonating a small bomb at the top of the hollow solid fuel core.

Personally I like the idea of resurrecting the F1, but the difference in experience and reliability levels between F1 and SRB vs J2 and SSME are considerable -- and in the latter case the J2 start is simpler than the SSME start.

Re:Not really a surprise (1)

sjames (1099) | more than 8 years ago | (#14625657)

F1 vs. SRB is a complex set of trade-offs. The SRB is extremely reliable (other than the o-ring problem). There's simply nothing to fail that results in thrust stopping (even in the Challenger failure, the SRBs kept thrusting). The F1 has many moving parts to fail and cause loss of thrust.

OTOH, the F1 can be shut down on launch and throttled throughout the boost phase as needed. The SRB cannot be throttled at all. The current SRB design doesn't allow for thrust vectoring at all.

Those are the reasons that the shuttle used both SSME and SRB for launch.

One nice thing about kerosene is that it doesn't boil at STP and so doesn't need foam insulation.

Re:Not really a surprise (0)

Anonymous Coward | more than 8 years ago | (#14627447)

OTOH, the F1 can be shut down on launch and throttled throughout the boost phase as needed.

The F-1 can't be throttled. As has been discussed throughout the thread, the center engine on the Saturn V first stage was simply turned off in flight to prevent the rocket from going over Max Q. (The maximum velocity that the aerodynmaic structure is designed to withstand.) If the fifth engine didn't cut out, the rocket would reach Critical Q, which is the velocity at which the structure begins to fail.

The SRBs are also designed to provide less thrust at different points in flight. All in-flight compensations (such as an Abort to Orbit) are performed by throttling the SSMEs. The SSMEs can even be overthrottled for liftoff and emergency situations.

Otherwise, you're on target.

Re:Not really a surprise (1)

JWSmythe (446288) | more than 8 years ago | (#14623814)


    Yup. SRB's are metal tubes full of solid fuel, that burn at a steady rate. They burn until they're empty. No choice on that. Once they start going, that's it. When they're done, they're hollow tubes that come crashing back down into the ocean.

    There is nothing technical to them. Joe technician goes out there with his zippo, and lights the fuses, and off she goes. :)

    (just kidding on the Zippo thing)

Re:Not really a surprise (2, Informative)

Profane MuthaFucka (574406) | more than 7 years ago | (#14620341)

You can't throttle the F1. It's either all-on or all-off. The Saturn V dealt with Max-Q issues by completely shutting down the center engine.

Re:Not really a surprise (1)

AKAImBatman (238306) | more than 7 years ago | (#14620434)

You can't throttle the SRBs either, so that's sort of a moot point.

The throttling on the STS (and presumably the CEV) design is handled by the SSMEs. The SRBs always put out their 3.3 million pounds of thrust. :-)

Re:Not really a surprise (2, Informative)

ericwhy (66607) | more than 7 years ago | (#14620776)

Actually, you can, and NASA does, throttle the SRB's. Actually, throttling isn't really the correct word, but by changing the shape of the solid fuel, SRB thrust is reduced by about 33% 50 seconds into the burn. After MAX Q, it is returned to maximum thrust.

See the section on SRB's here http://www.daviddarling.info/encyclopedia/S/Space_ Shuttle.html [daviddarling.info]

SRB and Temperature (1)

sconeu (64226) | more than 8 years ago | (#14621999)

The only thing that makes me leery of the manned configuration (J2 ontop of an SRB in a vertical stack): Have they solved the temperature related problems on the SRB yet? Or have they implemented a workaround of only launching in warm weather?

Of course, without an ET to catch fire and burn on the manned configuration, a Challenger type failure should be survivable due to an escape tower.

Re:Not really a surprise (1)

david.given (6740) | more than 7 years ago | (#14620766)

SSME (Space Shuttle Main Engines) - LHOx Fuel - 1.8 MN
SRB (Solid Rocket Booster) - Solid Fuel - 14.7 MN
J-2 (2nd and 3rd stage Saturn V) - LHOx - 890 kN
F-1 (1st stage Saturn V) - Kerosine - 6.7 MN

How do these compare to the disposable engines used on the latest Soyuz boosters?

Re:Not really a surprise (1)

AKAImBatman (238306) | more than 7 years ago | (#14621026)

They don't. Or more precisely, the Soyuz doesn't. It's not even in the same class. Here you go:

RD-117 - First Stage (4 Engines) - 838 kN
RD-118 - Second Stage (1 Engine) - 792 kN
RD-0124 - Third Stage (1 Engine) - 294 kN

You probably don't even want to see the Isp figures on those.

The four RD-117s in the first stage produce a total of 3.3 MN, or less than 1/4 of a single SRB. The second stage engine is about 100 kN less powerful than the J-2, and the third stage is about 1/3 as powerful as a J-2. In comparison, the Saturn V carried 5 J-2s on its second stage, and the space shuttle carries 3 SSMEs throughout its entire trip.

There was only a single J-2 for the third stage of the Saturn V, but like I said, it was about three times more powerful than the Soyuz third stage. More info on the Soyuz launch vehicle can be found on Wikipedia [wikipedia.org] .

If you want a real comparison (and a look at one of the odder designs in rocket engines), take a look at the Energia [wikipedia.org] .

Re:Not really a surprise (1)

david.given (6740) | more than 7 years ago | (#14621309)

They don't. Or more precisely, the Soyuz doesn't. It's not even in the same class.

Yeah, given a few moments thought I should have figured that out for myself. Soyuz launches a tiny capsule, the SSMEs launches a whole friggin' aeroplane...

According to the article you linked to Energia used RD-170 rocket engines, which produce 7.8 MN each. That's quite significant, and better than the F-1 according to the figures you gave. What's more, Wikipedia says that they're still in use by Sea Launch among others, which means there's a working production line.

Admittedly, I doubt they're man-rated, but it does raise the thought that NASA could probably save itself a shed-load of money by not developing its own engines and just buying RD-170s instead. It can't be purely political --- they quite happily buy RD-180s for the Atlas V.

Re:Not really a surprise (1)

AKAImBatman (238306) | more than 8 years ago | (#14622514)

Admittedly, I doubt they're man-rated

You're sure about that? [wikipedia.org]

Just so you're aware, the Energia was designed to carry the Russian Space Shuttle Buran. While no manned flights were ever accomplished (just a single, computer controlled flight), the rocket was ready for prime time.

But yeah, the RD-170 is an incredible engine. That's why they reworked it to create the RD-180 for the Atlas V. :-)

Re:Not really a surprise (0)

Anonymous Coward | more than 8 years ago | (#14622365)

Besides that, they were already planning to use the J-2 on the HLV. I imagine one of the pressures for making this decision was the possibility of having more commonality between the 2 launchers.

2018? (3, Insightful)

Etnie (11105) | more than 7 years ago | (#14619962)

I'm a bit confused as to how it takes us longer to get to the moon now than it did in the 60s.

Project Apollo was announced July 28th, 1960. July 20th, 1969, we set foot on the moon. Just under 9 years. (My dates may be a bit off.)

Even if you say the new project starts now, that's still 12 years. How frustrating.

Re:2018? (3, Insightful)

Kesch (943326) | more than 7 years ago | (#14620033)

There's probably a Murphy's Law of Government somewhere that the time it takes a government body to complete and action is directly proportional to the amount of regulations and oversight that exists. Regualtions and oversight are in turn directly proportional to the age and size of the government.

Re:2018? (5, Informative)

AKAImBatman (238306) | more than 7 years ago | (#14620080)

I'm a bit confused as to how it takes us longer to get to the moon now than it did in the 60s.

1. Money. If we spent as much today as we did on the Apollo program, we'd be able to get a craft ready in a very short period of time. (Note that while NASA receives more than enough money, most of it goes toward the Space Shuttle's maintenece and other projects.)

2. Technology. The industry that produced the Saturn V doesn't exist anymore, so it is not really possible to produce it again. We can produce a new rocket like the Saturn V (or buy off the Energia, take your pick), but that would just give us another moonshot rocket. What we want to build this time is an infrastructure that will keep us on the moon instead of merely sending up a few tons there and back.

If there was an emergency, I imagine we could get to the moon inside two years. Most of the lander equipment can be remanufactured and lifted by the Space Shuttle, and strap-on boosters could be lifted to propell the module. But that's not the point. That's why we're doing this the right way this time. Or to put it in perspective, the Apollo missions started out with 2,900 tons of hardware. They came back with about 6 tons. That means that they expended 2,300 tons of hardware to get 3 people to the moon and back. That's a hell of a lot of waste! :-)

some numbers (4, Informative)

Quadraginta (902985) | more than 7 years ago | (#14620672)

Apollo cost about $135 billion [wikipedia.org] in 2005 dollars, and the CEV is expected to cost $15 billion [wikipedia.org] .

Re:some numbers (2, Interesting)

DerekLyons (302214) | more than 8 years ago | (#14622444)

Apollo cost about $135 billion in 2005 dollars, and the CEV is expected to cost $15 billion.
Note that you are comparing apples (the cost of the entire Apollo program) to oranges (the cost of one spacecraft program).

The whole VSE pork barrel includes the CEV, two new shuttle 'derived' launchers, the lunar modules, launch pad modifications, VAB modifications, new buildings and trainers, etc..., etc... *That* is what you should be comparing to the cost of the Apollo program.

(For reference, the Apollo CSM project *alone* cost 17 billion 2005 dollars.)

Re:some numbers (1)

Quadraginta (902985) | more than 8 years ago | (#14622711)

Eh, I know, and thanks for the addition. But maybe it's not apples to oranges so much as Fuji apples to red delicious apples.

I debated whether to cite the cost of the Apollo booster alone, or the CM, to the CEV, because the CEV isn't just a new crew module, but on the other hand it's going to make considerable use of existing booster tech (e.g. the SRBs). Then I thought about the fact that I dunno if the cost cited by Wikipedia includes operating costs on the ground or not, some of which in the 1970s were borne by the military and didn't appear on NASA's budget, and then I thought about the fact that NASA estimates the CEV budget at $15 billion, and who knows what it will in fact cost and then...I gave up and pushed "Submit" 'cause I just meant to give a rough clue.

Re: waste? (2, Insightful)

Migraineman (632203) | more than 7 years ago | (#14620930)

The expendable portion of a lunar mission isn't necessarily waste. You took a bunch of survey equipment (including a golf cart) to the moon. Why would you expend structure and fuel to bring it back? Similarly, you need structure and tanks to contain the fuel you're using to get to the moon. When the tanks are empty, why would you haul that empty (and now useless) mass around? Nope, the most efficient method requires you to be an interstellar litterbug. As soon as a resource is depleted, you jettison as much as you can.

In space, mass is the one variable you can control. Escape velocity, orbital velocity, and a host of other parameters are dictated by the math - your orbital altitude is a function of your velocity, not your mass. So to obtain a particular orbit, you need to achieve velocity V. The energy required to do so is dictated by E = 1/2mv^2. There's a direct relationship between the mass of the vehicle and the energy required to achieve a particular delta-V.

If you look at the Rocket Equation [wikipedia.org] , you'll see that the overall relationship between wet mass (fuel) and dry mass (structure + payload) is exponential in nature. At the bottom of the Wiki page (link above) there's an example comparing single- and two-stage-to-orbit vehicles. All things being equal, the two-stage vehicle can put more mass into LEO by shedding the first stage.

Besides, bringing back used equipment is usually pointless. All of the Apollo-era vehicles used ablative shielding techniques, and couldn't be re-used (by design.) The Shuttle is technically re-usable, but it's largely rebuilt in-between flights. It pays a huge penalty in payload mass in exchange for bringing the brick-lined wings on a round-trip journey.

Re: waste? (1)

AKAImBatman (238306) | more than 7 years ago | (#14621173)

The expendable portion of a lunar mission isn't necessarily waste. You took a bunch of survey equipment (including a golf cart) to the moon.

It wasn't really cargo, though, because we had to send up one with each mission. If the rovers were reusable, I would concede the point. Same with the lunar lander. (14 metric tonnes) The RTG generators used for lunar experiments have been in continual usage, however, and meet the critera of cargo.

Unfortunately, even if you didn't count all of this as direct waste, the Saturn V rocket itself easily eclipsed any amount of hardware that actually made it to the moon.

Besides, bringing back used equipment is usually pointless.

Not true. If you can reuse a rover, you can bring something else next time. If you can reuse a LEO to LMO shuttle, then you don't have to relaunch another craft. If you can reuse a pair of SRBs, you can save money by not manufacturing new ones. That is the infrastructure the CEV will put in place. The Saturn V program never had such an infrastructure, nor did it intend to. It was a simple, "Get up and get the hell back down" mission.

Re:2018? (1)

DerekLyons (302214) | more than 8 years ago | (#14622416)

The industry that produced the Saturn V doesn't exist anymore, so it is not really possible to produce it again. We can produce a new rocket like the Saturn V (or buy off the Energia, take your pick)
The Energia is just as dead as the Saturn V.
What we want to build this time is an infrastructure that will keep us on the moon instead of merely sending up a few tons there and back.
Which is precisely what NASA isn't doing. The current scheme, just like Apollo, will end up providing expensive white elephants. Too expensive to keep us on the moon.
f there was an emergency, I imagine we could get to the moon inside two years. Most of the lander equipment can be remanufactured and lifted by the Space Shuttle, and strap-on boosters could be lifted to propell the module. But that's not the point. That's why we're doing this the right way this time.
Expensive new launchers with virtually zero use beyond the moon mission isn't the right way - but it is how NASA is doing it.
Or to put it in perspective, the Apollo missions started out with 2,900 tons of hardware. They came back with about 6 tons. That means that they expended 2,300 tons of hardware to get 3 people to the moon and back. That's a hell of a lot of waste! :-)
The Porklauncher V [wikipedia.org] and Porklauncher Ib [wikipedia.org] are not significantly better.

Re:2018? (2, Interesting)

AKAImBatman (238306) | more than 8 years ago | (#14622716)

The Energia is just as dead as the Saturn V.

Funny, I coulda sworn I saw some Zenits and Atlas Vs flying.

The Energia is far from "as dead as the Saturn V". Most of the technology is still in place, and much of it is still in use. As far as rockets go, it was one of the best pieces of engineering that Russia ever produced.

Which is precisely what NASA isn't doing. The current scheme, just like Apollo, will end up providing expensive white elephants. Too expensive to keep us on the moon.

You keep telling yourself that. I, on the other hand, will be gleefully awaiting the launch of the Earth Departure Vehicle and the Lunar Surface Access Module. Reusable components that will take us to the moon the same way we should have gone the first time. Not the mention the wonderous joy of having a superbooster back on the payroll that isn't attached to a 109 metric tonne pair of wings. Can you say, "Space Station Freedom in 2 flights?" (Yep, 250 tonnes in two goes. So much better than dozens of Shuttle flights.)

Expensive new launchers with virtually zero use beyond the moon mission isn't the right way - but it is how NASA is doing it.

Pardon me, sir, but you don't know what the hell you're talking about. There is absolutely nothing mission specific about the "Porklauncher V" (like the name, BTW). The "Porklauncher Ib" as you call it, is mission specific, but that's not a big deal. It's the HLV that's interesting. Just as the Saturn V boosted Skylab in a single launch, and was going to boost the mini-Orion in a single launch, so will the Shuttle Derived HLV be able to launch extensive, and useful payloads.

Would you rather NASA followed the original "Orbital Space Plane" plan? (Now THAT was stupid.)

Re:2018? (2, Insightful)

bhima (46039) | more than 8 years ago | (#14623970)

Actually I've thought for a while that the US should be paying the Russians to host all of the American launches using chemical engines.
Hell the EU should probably do the same thing. I wonder how much more science we could do if we subcontracted with Russians for launch vehicles?

That would free many scientists & engineers to concentrate on newer more novel ways to get into orbit that don't include sitting on top of a bomb. Really there now there isn't an advantage to have US, French, British, Russian, &tc... designed chemical rocket engines, when everyone knows they suck. Once a working alternative has been demonstrated, the Russian scientists & engineers can transition from designing & building chemical launch vehicles to building a working production version this new launch system. Given the current cost of launches... I would imagine the incentive to build and operate an alternative that is safer & cheaper would be quite high.

I've given up on the Americans actually producing an actual spacecraft capable of supporting human life... they don't have the political willpower or national vision required.

Re:2018? (1)

JWSmythe (446288) | more than 8 years ago | (#14623880)


    You don't have to launch with 2,900 tons of stuff. You have to launch with a crew and oxygen to get them to the ISS.

    There are Soyuz and Progress launches almost every month, carrying stuff up each time. They could make the launches more frequent, and assemble the ISS to Moon vehicle there. They could even bump an unmanned vehicle from the ISS to a moon orbit, and wait for the crew to get there to land it. They'd just need a nice comfortable vehicle big enough for the crew to travel in, with supplies for the trip.

    Won't happen though. Ya, I'm very optimistic about our real push for space travel.

Re:2018? (1)

justins (80659) | more than 8 years ago | (#14625850)

If we spent as much today as we did on the Apollo program, we'd be able to get a craft ready in a very short period of time.

There's nothing in the world to support that contention. It seems a lot more likely that if we spent as much today as we did on the Apollo program, we would get a lot less, thanks to the bureaucracy and regulatory mess.

Re:2018? (1)

chinton (151403) | more than 7 years ago | (#14620285)

Last time we were going for the sole purpose of beating the Russians there. This time we are (presumably) going there to stay.

Re:2018? (1)

queazocotal (915608) | more than 7 years ago | (#14620499)

Unfortunately not.
This is not that much more than Apollo.
A few people on the moon, for a bit longer than apollo.

No manufacturing things from lunar resources, or long-term bases at all.
More up to date sensors on the experiments of course, which is nice.
No significant development of anything that will make spaceflight cheaper.
It's been $10K/lb (approximately) since the end of apollo, and it still is.

Re:2018? (1)

duhjim (733407) | more than 8 years ago | (#14624592)

im afraid we are going there to occupy the high ground and to threaten to drop boulders on those who threaten us.

Re:2018? (1)

Average_Joe_Sixpack (534373) | more than 7 years ago | (#14620466)

Even if you say the new project starts now, that's still 12 years. How frustrating.

I got news for you, it's not gonna happen ... not with an 8 trillion (and growing) debt, not with the pending baby boomer retirement and especially not with the US mired in a perpetual war. We'll be lucky to see the JWT launched before things go to shit.

Time dilation. (1)

jd (1658) | more than 7 years ago | (#14620486)

As the mouths of politicians travel close to the speed of light, time slows down. Thought everyone knew that.

Re:2018? (1)

Waffle Iron (339739) | more than 7 years ago | (#14621215)

I'm a bit confused as to how it takes us longer to get to the moon now than it did in the 60s.

Back then, they only had to include about 50 kilobytes of software in the rocket. This time, there's probably going to be hundreds of megabytes of code. That's going to take a long time to write.

Re:2018? (1)

JWSmythe (446288) | more than 8 years ago | (#14623855)


    Don't forget, almost everything with the Apollo missions was new technology. We've played quite a bit with space travel and long durations in space.

    It wouldn't take 9 years to park someone's happy ass on the moon. I'd be willing to bet we *COULD* do it in a year, if the government(s) wanted to do it.

    Now, the "could" part of that, is if we were doing it right. If a *good* leader were to control the whole thing, keeping all parties happy and active. We *could* have everything done in a year. I say that as a could. Maybe it'd go over the allocated time, and take 16 months. :)

    It will never happen right now. The US Government is spending too much in stupid areas, like wars (war on drugs, war on immigration, war on the middle east, war on this, war on that). We also don't have the cooperation of the countries that could help us most. If we had China, Russia, Japan, and the European countries, that would be really helpful.

    Of course, it would also require opening up the "secrets" of the space programs from everyone involved. Since the world is in the "trust no one, hate everyone" stance, we'll never get it done.

    Hell, we could have probably put humans beyond Pluto by now, if we would simply cooperate.

Re:2018? (1)

WoodieR (860635) | more than 8 years ago | (#14624508)

many more opportunities for taxpayer money to end up in the (mis)appropriate hands ??? or merely because it's more expensive now - in modern dollars, and therefore must be spread out over more years ? or was the original merely a hoax, and now they're trying it for real ?

Re:2018? (1)

Alioth (221270) | more than 8 years ago | (#14626300)

The 1960s moon project was just an effort to get a man on the moon first at all costs, and beat the Russians. It was optimized purely to get that footprint and flag up there - not to do any real science or set up a real presence or Earth-Moon infrastructure.

To do it properly WILL take more time.

Freedom of speech (-1, Offtopic)

Anonymous Coward | more than 7 years ago | (#14620035)

Has this hit the US yet? Any papers showing solidarity with the Danes?

http://www.google.co.uk/search?hl=en&q=danish+cart oons+upset+muslims&btnG=Google+Search&meta= [google.co.uk]

http://www.welt.de/ [www.welt.de]
http://www.mediawatchwatch.org.uk/ [mediawatchwatch.org.uk]
http://news.bbc.co.uk/2/hi/europe/4670370.stm [bbc.co.uk]

Headlines in 2020 (3, Funny)

j_cavera (758777) | more than 7 years ago | (#14620430)

I can see this one coming:

In the latest round of budget cuts, NASA introduced plans to modify the CEV for the planned Moon landing in 2038. The original plan called for an updated J-2 engine first used on the Saturn V rocket. The new plan is to have a guy sitting on the outside with a fire extinguisher. The fire extinguisher engine was first used in a high-school physics lab in the 1930s. It is not expected to save any money in the near-term, but in the far term, it should be a cost saver since the technology already exists and is proven.

- Jim

And yes, I AM a rocket scientist...

Re:Headlines in 2020 (1)

AKAImBatman (238306) | more than 7 years ago | (#14620856)

Just a bit cynical, are we? :-)

I can understand your point (all too well I'm afraid), but you do have to admit that the CEV plan has really been shaping up. While just about every STS replacement technology before it tried to go for pie-in-the-sky technology, at least the CEV is mostly a matter of plumbing existing components together and certifying the sucker. It's not exactly a bold plan (any schoolchild could have come up with the idea of using the shuttle without the shuttle), but it at least is a good plan.

Erm... at least in comparison to the X-33 plan. (Let's see, take a dozen or so unproven technologies, mash them together into a vehicle, don't plan in any contingency for failed tech branches, and then expect the thing to fly right the first time? Good one!)

No problems? (1)

Mercano (826132) | more than 7 years ago | (#14620555)

In the 10 Apollo launches aboard the Saturn V rocket, there were no problems with the launch vehicle.

I seem to rember in Apollo 13 the center 2nd stage engine, a J-2, went out early. The flight computer burned the outter four a bit longer to compensate, but I'd still say that was a problem, if not with the engine itself, at least with the launch vehicle. Then theres the whole lightning strike thing on what was it, Apollo 12? SCE to Aux.

Re:No problems? (4, Informative)

rcw-work (30090) | more than 7 years ago | (#14620988)

I seem to rember in Apollo 13 the center 2nd stage engine, a J-2, went out early.

Dangerously strong pogo oscillations [yarchive.net] , which could have ripped the engine off the rocket, happened to trip a pressure sensor which caused the computer to shut down the engine.

Pogo was reduced to tolerable levels by the end of the Apollo series, and later engines such as the SSME were designed to eliminate it entirely.

Re:No problems? (2, Interesting)

Ellis D. Tripp (755736) | more than 7 years ago | (#14621239)

The lightning-induced problems on Apollo 12 were isolated to the CSM, not the booster. In fact, the booster's guidance system is all that got the crew into orbit, because the CSM guidance system crashed along with most of the electrical system after the second lightning strike.

Re:No problems? (0)

Anonymous Coward | more than 8 years ago | (#14621849)

Yes, the Saturn V had numerous problems, including premature engine cutoff, potentially-ship-destroying oscillations, and many others.

What makes the Saturn V remarkable isn't its lack of problems. It's the fact that, despite all of these problems, nobody died. You could take a Saturn V and shake it like crazy, hit it with lightning, cut off fuel to an engine, and the mission could still proceed. With the Shuttle, you launched on a day that's a little too cold, or a chunk of foam fell off in the wrong way, and everybody died.

And this is why the Shuttle is a bad design. It's not so much the number of problems, but the robustness of the system. For safety, reliability, and cheapness, it's necessary to have a robust system which can have major failures and still get the job done. The Shuttle has proven twice in spectacular fashion that it cannot.

There's an opinion piece as to how NASA (4, Interesting)

multiplexo (27356) | more than 7 years ago | (#14620689)

is turning the CEV into the same sort of flying clusterfuck as the Space Shuttle at:

http://www.space.com/adastra/adastra_tumlinson_060 130.html [space.com]

At this point I would rather save money by ending NASA's manned space program instead of continuing to piss money down ratholes such as the Shuttle, ISS and now the Crude Exploration Vehicle all of which are just ways for NASA to hand money to large aerospace companies so that they can pad their bottom lines and continue to bribe congressmen.

Re:There's an opinion piece as to how NASA (1)

willith (218835) | more than 8 years ago | (#14621800)

That article seems particularly concerned with forsaking methane for hypergolic fuels in CEV. There's a very good reason to use hypergolic fuels in a space vehicle--simplicity. A hypergolic engine doesn't need an ignitor or any form of electrical power to start--all you have to do is open the valves, which can be done by hand, and the engine will light when the reactants meet in the combustion chamber.

If you have a damaged vehicle, the lack of a complex ignition system is another layer of redundancy to help get a potentially stranded crew back home.

Re:There's an opinion piece as to how NASA (2, Insightful)

multiplexo (27356) | more than 8 years ago | (#14622260)

Yes, and the price for using hypergolic fuels is that the ground support infrastructure is very complex and the fuels are dangerous, toxic and expensive, which is why everyone who builds rockets has been moving away from them for the last 40 years or so. So the trade-off for a theoretical advantage in flight due to an added layer of redundancy is a huge and expensive layer of complexity on the ground to handle and store these fuels. Oh, and you lose some performance too, the specific impulse for hypergolics isn't as good as LOX/methane.

Re:There's an opinion piece as to how NASA (1)

R3d M3rcury (871886) | more than 8 years ago | (#14622035)

Well, as always, there's that question: How much money should NASA spend on researching new technologies when the old technologies are "good enough"? The linked article, in some ways, and your opinion show the duality of this question.

For example, you mention the "flying clusterfuck" of the Space Shuttle. I might agree, though I'd point out that many of the Shuttle systems are pinnacles of 1970s technology. Remember that, for the Shuttle, they created all new systems. Rather than using the old heat-shield that had served NASA well for 20 years or so, NASA developed a new system using thermal tiles. Pretty much everything in the Shuttle was developed from scratch.

The article you reference complains about how NASA is using tried and true technology in the CEV rather than some new experimental system which would cost more money to develop into a reliable system. But the author points out that NASA used "untried" systems on the Shuttle (SRBs, for example) so why, he asks, aren't they willing to do this on the CEV? But by using untried systems, wouldn't that help create more of a "flying clusterfuck"? So wouldn't it be better to use the tried, tested, reliable, and cheaper systems on the CEV? But according to what you're saying, that's turning it into the same kind of "flying clusterfuck."

So which is it? Should NASA be developing all new stuff for the CEV and pushing the state-of-the-art? Or should they be playing it safe and cheap? If they go state-of-the-art, will you complain about how NASA is taking too long and wasting too much money? If they stick with the tried-and-true, will you complain about how NASA isn't pushing the state-of-the-art?

Re:There's an opinion piece as to how NASA (1)

multiplexo (27356) | more than 8 years ago | (#14622343)

I'm a huge fan of the "if it ain't broke, don't fix it" school of design. On the other hand there are times when that doesn't work. The question with the CEV is whether or not NASA is going to turn this into another flying clusterfuck like the Shuttle, which NASA appears to have every intention of doing.

NASA's decisions in the 1970s on the Shuttle made short term budgetary sense but were catastrophic in the long term. The SRBs were an unproven technology that was used not because it made good engineering sense, Von Braun was appalled by the idea of launching a manned vehicle with solid boosters, but because NASA was too cheap to invest money into developing a completely liquid fueled booster for the Shuttle. NASA was facing budget cuts in the 1970s after Apollo and NASA management made the decision to lie to Congress and the Air Force about the capabilities of the Shuttle and about how much money was necessary to fly it. Rather than go to Congress and say "Hey guys, if you want us to do this right it's going to cost X dollars" NASA management lowballed their estimates, missed all of them anyways and ended up with a vehicle that has accomplished nothing significant in the last 25 years that could not have been done with Saturn IBs and Apollo capsules.

As far as the tile system goes not every new technology works out as well as intended. However that's another stupid argument that's totally irrelevant here. NASA will save a few bucks in the short term by using hypergolic fuels in those tried and true tested motors. On the other hand the long term costs of supporting hypergolic fuels will dwarf any savings in the present and will lock our efforts into using toxic fuels and 1950s engine technology. NASA will also end up with a system which is not sustainable or scalable. Yeah, "if it ain't broke, don't fix it" is a good rule of thumb but it has to be balanced with questions of long-term sustainability and scalability. I don't see that NASA is interested in any of that, they don't care about doing it right as long as they keep getting paid. If they did they'd go to Congress and say "The Shuttle and ISS are worthless wastes of money, let's use that funding for developing new vehicles that will actually allow us to do some exploration of some locale other than very low earth orbit."

This is starting to sound familiar (0)

Anonymous Coward | more than 8 years ago | (#14621841)

Now I remember! [imdb.com]

Misleading. (4, Informative)

DerekLyons (302214) | more than 8 years ago | (#14622332)

In the 10 Apollo launches aboard the Saturn V rocket, there were no problems with the launch vehicle.
This is a bit misleading, the summary starts out talking about the engines, the swaps to the launch vehicle. In fact, the J-2 engines had considerable problems on the flight of Apollo 6 [wikipedia.org] . The pogo problem was not cured until Apollo 14. (In fact, though it was overshadowed by later events, it came quite close to causing an abort on Apollo 13.)

In fact, when the Apollo series is looked at critically - one becomes astonished by the number of near misses and diving catches. NASA was lucky, very lucky.

Re:Misleading. (1)

justins (80659) | more than 8 years ago | (#14625767)

This is a bit misleading, the summary starts out talking about the engines, the swaps to the launch vehicle. In fact, the J-2 engines had considerable problems on the flight of Apollo 6 [wikipedia.org]. The pogo problem was not cured until Apollo 14. (In fact, though it was overshadowed by later events, it came quite close to causing an abort on Apollo 13.)

Isn't pogo more about the design of the rocket as a whole than just the engine, which is the part that is being considered here? I really don't know, I'm asking, but you're talking about oscillation between the engine and the rest of the booster, right?

In fact, when the Apollo series is looked at critically - one becomes astonished by the number of near misses and diving catches. NASA was lucky, very lucky.

That was largely by design, in a way. I read something recently quoting Armstrong as saying he figured at the time that they had a fifty-fifty chance of making it to the moon and back successfully. They all sort of understood that what they were trying to do was pretty risky and put as brave a face on it as they could. That's not quite the same as the NASA of today, which apparently believes its own BS at many times.

They're both obsolete (0)

scotty1024 (584849) | more than 8 years ago | (#14622613)

NASA needs to start thinking outside the 1930-1970 technology box they keep finding themselves trapped in. Both engines are hopelessly obsolete. The current shuttle main engines have a poor reliability track record and have materially increased the cost of the launches by constantly delaying launches or forcing costly orbiter engine replacements. The J2's have nothing like the POH's of the shuttle main engines, so God only knows what their long term reliability is.

For example, whilst NASA dozed off, the military has become very proficient in the applications of U-238.

U-238 would make an excellent replacement for the tissue delicate RCC blocks on the shuttle leading edges, and the CEV's high temperature re-entry components. But instead NASA's "Rocket Scientists" sit around publishing papers about how difficult it is to bond foam to a cryo fuel tank. Hey, if you can't make the foam stick on, why no fix the real issue: the damn RCC is too delicate. Replace the RCC and the shuttle can survive other things than pieces of foam striking it during lift off. We need a shuttle that works like a military duce and a half, not a pimp mobile that blows up on re-entry because a 5lb piece of foam hit it during take off.

NASA could also find lots of available talent for engineering U-238 into rocket nozzles to produce more reliable rockets for primary thrust and orbital adjustments. These engines could be tested on the shuttle fleet. NASA doesn't like to talk about it, but I don't think they have a single shuttle still running on original engines. So keep on swapping out engines.

Similarly aerogel's could be used to update insulation systems, acoustic heat pumps engineered in for cooling along with modern nano material heat radiation systems and newer higher capacity fuel cells could be employed. Perhaps even employ reformer technology so the fuel cells could be fueled by alchohol/gasoline rather than the much more difficult to handle (and far more dangerous) liquid hydrogen.

NASA is also way behind the times in space suit design. I read this puff piece NASA produced about a women sewing space suit gloves and how she helped sew a better glove for her astronaut Father. Why isn't she using 3D scanning and CAD with NC sewing? Where are the phase change materials? Where are the RTD heater/energy units or enhanced chemistry/nano material battery systems? Where are the MEMS cryocrackers to remove CO2 and crack it back to C and O2?

NASA spin off technology helped develop all kinds of consumer technology back in the 60's and 70's, but what have you done for us lately baby? NASA money into reformers and CO2 crackers would have a large impact on many consumer technologies, including Bush's new program to kick our dependence on oil.

Time to stop living on past achievements and create new ones.

Re:They're both obsolete - MOD parent down (1)

slightlyspacey (799665) | more than 8 years ago | (#14623321)

You're kidding right? What a wonderful idea! Let's replace the RCC with depleted uranium (U-238)which is 70% denser than lead and as a bonus a pyrophoric on a vehicle that is traveling at Mach 25 when it re-enters the earth's atmosphere. Why don't we just go ahead and replace the RCC with C4? The result would be the same and we would save money. Ditto with manufacturing the main engines out of U-238.

Apart from ICBMs, I don't know of any military vehicles that would survive the harsh re-entry conditions that the shuttle is asked to endure every mission. Hmm, maybe we should use the same materials that are used to help ICBMs survive ... oh wait, that would be reinforced carbon carbon.

This isn't Star Trek, we don't have anti-gravity devices, nor magical force fields that would protect the vehicle. This really is rocket science and it is tough and risky.

 

Re:They're both obsolete (1)

AKAImBatman (238306) | more than 8 years ago | (#14623425)

Thank you Scotty, that was downright hilarious! I don't think I've had that good of a laugh in a long time.

Here's hoping you get +5 Funny. :-P

Re:They're both obsolete (1)

duhjim (733407) | more than 8 years ago | (#14624682)

How would building a space elevator change the equation?

Re:They're both obsolete - MOD PARENT UP (1)

slightlyspacey (799665) | more than 8 years ago | (#14624772)

OK, I admit it ... you snookered me. Congratulations, it doesn't happen all that often, but you got me real good :):):)

Doesn't that defeat the purpose of the program??? (1)

dtolman (688781) | more than 8 years ago | (#14624843)

One of the original stated benefits of the program was that by tinkering a little with shuttle derived components, they could create new launch vehicles without much new work. If they aren't using shuttle parts, why the hell don't they just design a new vehicle from scratch?

Re:Doesn't that defeat the purpose of the program? (1)

RoboRay (735839) | more than 8 years ago | (#14624881)

No, it doesn't defeat it at all. They will still be tinkering with pre-existing, proven hardware. Designing a new engine from scratch and flying it dozens of times to obtain the same confidence in it's reliability that we have about the Saturn, Apollo and Shuttle hardware would be vastly more expensive.

KISS (1)

MikeyToo (527303) | more than 8 years ago | (#14626196)

Personally, I think that someone at NASA finally woke up. Using an SSME in an expendable sustaner configuration is like shooting a thoroughbred racehorce after one race. You might win the race, but you paid way too much for it.

People keep saying "well, we haven't made J-2's in 30 years". Well, nobody has made an airstart-capable SSME ever. Either way, changes will have to be made in production. Airstart isn't just a matter of throwing a switch and having the thing light up. Someone in a previous post mentioned the Atlas. One of the tenents of it's original design was a ground start for all engines, due to worries over staging failure. According to Encyclopedia Astronautica: "It was estimated by ATK Thiokol in 2005 that restarting the J-2S program, including engine fabrication, design and reliability verification, certification, and production, would require four years. Although no J-2S tooling was known to exist, modern soft tooling could be developed quickly and less expensively than the original hard tooling. There was an existing manufacturing and supplier network in place to support a J-2S restart." How long would it take to develop the airstart-capable SSME?

There was also some talk earlier about J-2 failures in Saturn V launches. When that did occur, the other engines were burned longer to "take up the slack" caused by the lost engine. What happens if the single modded-SSME fails in the sustainer stage? You start wondering where you'll land.

Then there's the KISS factor. Everyone has been talking about performance issues, but the J-2 wins by a landslide in KISS. The bonus is that given the advancements in technology since the original J-2 in 1960 should provide excellent advancement in performance over the original item. In fact, a modified J-2S was used as the basis for the X-33 linear aerospike engine. This is not some old POS that they're dusting off to keep someone happy. It was chosen because of the extensive design studies and testing done on this engine since it was first built.

The J-2 also adds to the nostalgia value and cool factor. It helped us to get to the moon before, it would be great if it helped us get back.

Thanks to Encyclopedia Astronautica and Mark Wade for references.

A Dying Empire (1)

J.R. Random (801334) | more than 8 years ago | (#14626881)

In the 1960s it took America slightly more than 8 years to go from a dead start (John Kennedy's initial announcement of the moon program) to landing on the moon using a J-2 engine. Now, 40 years later, it's going to take 12 years to land on the moon again, using a J-2 engine. My country peaked a long time ago.
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