F-22 production termination is premature

[TallDave]

That is absolutely not true. You know space is one thing most of all: Empty!

I mean the cost is zero relative to the cost of getting out of Luna's gravity well.

Water on the moon can be used for making fuel and for storing solar energy for night in Fuel Cells.

You know what doesn't have a night at all? A random point in space. Another advantage for ARPIS!

You can also make water for consumption by humans. All that would cost a lot of money if it had to be transported somewhere.

Yes, I think it's possible Luna could serve as a cost-effective source of water and water-based fuel at some future point, perhaps when unmanned factories can set themselves up. I'll bet it isn't any cheaper than lifting it from Earth for quite a while, though.

You can also provide radiation shelter for your workers easier on the moon than you can orbit.

How do you figure? There's no atmosphere. Are you talking about building a shelter with Moon rocks?

[kunkmiester]

any sort of space construction will be expensive, whether it's on the moon or in orbit. Unless and until you can reach the asteroid belt though, materials WILL come out of a gravity well. The lifting costs off the moon will be so much lower than off earth regardless of method, that material, particularly low value material like fuel or food, will pay for any infrastructure relatively quickly.

[Skipjack]

Yes, I think it's possible Luna could serve as a cost-effective source of water and water-based fuel at some future point, perhaps when unmanned factories can set themselves up.

Splitting water into hydrogen and oxygen is easy, very easy. So that does not cost much of anything at all.

I'll bet it isn't any cheaper than lifting it from Earth for quite a while, though.

A pound of payload into orbit still costs a lot of money. It depends on how far you look into the future. Do you want to do a quick Apollo style space exploration, or do you want to build a space infrastructure?
Apollo was an achievement, but ultimately it did not last. We have to do it now all over again to get to the moon. A good plan for space exploration would focus on a working and affordable infrastructure for any future mission before sending anyone anywhere.

How do you figure? There's no atmosphere. Are you talking about building a shelter with Moon rocks?

You can use the water from the moon as a shield, or you can dig caves (or use natural ones, if something like that exists), or cover shelters with moon rocks as you said.

[93143]

Okay, commercial break's over, back to Skipjack vs. Threadjack...

Actually, I'll probably be getting fairly busy in the next several days, so I'll try to put the brakes on after this... feel free to reply, but I may or may not get to it in a timely fashion...

I may also try to condense this post a bit; it's really long and actually kinda repetitive...

NASA is indirectly and directly responsible for this mess.
1. They fail to build RLVs due to politics and polticialy motivated decisions.
2. To cover their shameful failures, they use the lame excuse of "RLV is impossible with current technology". Everyone believes it (since NASA says it after all) and that is the end of any seriously funded development on that matter.
2. They offer heavily subsidized launches on the shuttle and refuse to buy from 3rd parties (until now that the shuttle is retired).

This caused a climate of stagnation in Space launcher development.

I contest your interpretation.

As far as I know, NASA hasn't said RLVs are is impossible. The fact is, lots of private concerns have tried to develop a cheap RLV and failed. Some of them managed to blow a fair amount of cash before their schemes collapsed, but most of them just talked a good game and then disappeared. NASA isn't alone here. It's just that cheap RLVs aren't all that easy to develop, and neither the U.S. government nor private investors have the necessary patience to actually fund one to completion. We barely got Shuttle, and that was in the afterglow of Apollo...

Skylon is an interesting concept, but not the only concept for an SSTO- RLV. In fact some might argue that there are simpler ways to achieve a simillar goal (e.g. VTOL concepts).
Still, it is true that any RLV will have comparably smaller payloads. To me this only means that you will need more flights, orbital debots and assembly, etc Thats all.
Or, you build different launchers for different purposes.
After all, you dont use a delivery truck to go to work every day, do you?

Either way, RLVs can do the job, or at least part of the job just fine.

Where did I say Skylon was the only concept available? Where did I say there was no place for an RLV in an exploration architecture? Stop misrepresenting me.

A couple points:

VTOL SSTO concepts almost have to be all-rocket. This kills the performance because the mass fraction has to be insane. The only known chemically-fueled airbreathing engine concept that changes this picture significantly (in a good way, that is) is SABRE. Skylon D1 puts up 50% more payload than DC-1 was projected to, at roughly half the GLOW - and it's way more robust to unexpected mass growth.

Assembling pieces in orbit is a major pain and should be avoided whenever possible. Remember, spacecraft costs dwarf launch costs even on today's rockets, so the less complex the spacecraft, the cheaper the mission. Monolithic ground-assembled hardware also reduces mission risk in a variety of ways.

Absent a huge technological leap like Polywell or M-E drives, I don't see anything coming that could do the exploration job significantly better than Jupiter.

I dont agree. I do see the benefit of Polywell and M-E drives and that is one reason why I am on this board. I do however think that RLVs are possible without this technology.

I do too.

However, I don't think they constitute a replacement for a heavy lifter. Exploration spacecraft cost more than their launchers, by a sizeable factor. Breaking them up into little bits so you can spend 3% instead of 30% of their cost launching them, in the process inflating their cost and increasing mission risk substantially, is not the way to do exploration.

Now, a Sea Dragon style vehicle might be a good idea, if it could be made reliable enough, and if there was something to do with it that would justify the development cost. But right now there isn't, and if we don't start getting out of LEO and doing stuff, there never will be.

Read up on the X33 please. NASA scrapped it after massive cost overruns. The cost+ contract system employd by NASA is unsuitable for this kind of development nowadays. It worked during Apollo days, but not now. NASA needs to employ fixed cost contracts and competitions with milestones.
Also read up on the DC-X to see how political decisions got a good project cancelled after a minor setback. The DC-X was cheap compared to what the paper rocket Constellation has cost so far.

I know all about VentureStar and the DC-1, thank you very much.

Yes, NASA needs fixing. They've been operating under extreme political and budgetary pressure since before the first Apollo moon landing, trying to accomplish great things (getting jerked around by the ever-fickle U.S. government as regards which great things precisely) with barely enough money to get by. The state of NASA now is a result of complex interplay of a number of factors; you can't just blame NASA.

Oh yes, and cost plus contracts encourage waste and should be done away with as soon as possible. Projects get huge numbers of engineers assigned to them just to drive up costs, and it actually slows down development because there's more coordination and dragging around dead weight going on than actual work...

Now they've finally got an idea they can execute quickly and cleanly without a huge plus-up, and you want to pull the plug?

I doubt that they will select DIRECT.

That's less than irrelevant to the question of whether they should or not. As far as I can tell, you're arguing that they shouldn't.

It is technologically not a big step foreward from Apollo and IMHO a step backwards from the Shuttle. I am speaking technologically.
Also the development cost is way to high for what is achieved with this. Ares would still be very expensive too.

The fact is that chemical rocket technology is mature; it hasn't advanced all that much since Apollo, and it won't get substantially better than it is now no matter how long you wait. So what if the Orion's MPS is the same engine as Apollo's MPS (and the Shuttle's OMS too)? It's a good engine. Internally, Orion and Apollo are very dissimilar; Orion looks sort of like Apollo but inside it's a very advanced, modern spacecraft. I'm not sure what you could possibly be complaining about, except the shape. Altair even more so - the Apollo LEM wasn't even in the same league as Altair or any concept that could end up replacing it.

Sure, Shuttle can do things Orion can't. Well, Orion can do things Shuttle can't. It's designed for a different mission.

You're not being consistent. You acknowledge the problem of lost know-how. You say "walk before we run". Yet you complain that the Constellation spacecraft aren't a vast enough technological leap over what we used last time we did something we're trying to relearn how to do in the first place?

Jupiter would cost less than $4000 per kg to orbit. That's better than the projected numbers for the Falcon 9, and it's based on very well known quantities (STS costs).

If you need that many heavy payloads, which is rarely needed other than for "exploration".

If we're not going to do exploration, there's not much point developing Jupiter, now is there?

Six flights per year should get you below $5000/kg. That's two lunar missions and a couple of standalone J-130 flights. Surely we have funding for that. DIRECT seems to think they can double that mission rate without busting the budget, maybe fit in a NEO mission now and then...

Please also forgive my skepticism towards the price predictions for DIRECT. I doubt it will be as cheap in the end. Also factor in the initial development cost.

That cost already includes amortized development cost. And it's got substantial margin built in (more than 30% IIRC). Apparently the Aerospace Corporation basically confirmed the DIRECT team's cost estimates when they analyzed it. Also, the costs for DIRECT are better founded than the costs for the Falcon 9; STS is a very well characterized system, and LC-39 is a known quantity in terms of operations, but Falcon 9 hasn't flown even once yet.

I cheer for SpaceX too. But we're having an argument here, and I can't afford to pull too many punches...

But they dont need NASA to pay them for exploration missions in order to have a profitable launcher. The most expensive part of making their Dragon capsule manned is the escape system. The cost for this is some 300 million USD. That is all they want NASA to pay for (other than the launches themselves). A ridiculously small price compared to anything NASA could come up with.

SpaceX has absorbed a lot more cash from the U.S. government than that... if you want a heavy lifter out of them, prepare to shell out many billions and wait a long time.

Or just wait a long time - something like that seems to be in their plans anyway. I'd rather get going with what we have now, and if SpaceX can someday get a lander down near NASA's Shackleton Crater base and have an astronaut step out and shake hands with the base commander, great. It's more likely to happen if they can make a lot of R&D capital launching liquid oxygen to LEO in support of NASA's effort.

Remember, NASA doesn't have to make a profit doing this. I think it's still worth doing.

So how is buying launch services from SpaceX fundamentally different from buying them from Boeing, Lockheed Martin, ATK, USA and the rest? The company profits from the money the government is paying them. That goes into salaries and bonuses and whatnot, and is eventually rolled back into the economy.

SpaceX is cheaper.

Not much, even assuming the exploration vehicles won't get any more expensive if they have to launch dry on a few Falcon 9 Heavies and hook together/tank up on orbit... I wouldn't really object to that too strongly if it could be pulled off; anything is better than nothing...

Space industry veterans tend to feel that SpaceX hasn't really felt the bite of all the overhead that goes with operating a major launch business yet, and that once they do, their costs will go up, not down. I'm a little more hopeful, even though in the past their cost estimates have most certainly gone nowhere but up - they have, after all, already launched a small commercial payload on a light LV, so hopefully they have something of a handle on it...

But they're also not as safe a bet.

If DIRECT is selected, NASA and its OldSpace contractors will be able to make Jupiter fly, safely and routinely - and soon. SpaceX hasn't demonstrated anything yet as regards a launch vehicle the size of Falcon 9, never mind anything bigger, with the possible exception of the increasingly obvious fact that they can't hold to a schedule any better than NASA can.

I can't emphasize this enough: Jupiter is a short, easy step from what we have now, and can be flying soon enough to preserve NASA's workforce and infrastructure and take advantage of all the knowledge it has accumulated flying Shuttle for 30 years. Never mind that it's also a unique capability worldwide, both in terms of mass and volume to orbit, scalable and versatile in a way neither Ares rocket can ever be. It's low-hanging fruit, but if we don't grab it soon it will be too late.

SpaceX, on the other hand, is a gamble even for ISS support. Depending on them for exploration missions is insane.

If the answer to the first question is "stay in a holding pattern in LEO until we figure out how to make it cheap", then NASA might be better off getting out of the launcher business altogether.

Exactly what I am saying.
Otherwise anything we do is going to be temporary like Apollo. Nothing that has a lasting effect.
Even the ISS already has an expiration date, due to the expense of getting supplies into orbit. That is what I call a waste of money!

As I said, exploration spacecraft cost a lot more than their launchers. Cheaper launchers can help (otherwise there'd be no point to choosing Jupiter over Ares), but ultimately what we have is good enough to start exploring with. Even if the launchers were free, the spacecraft for a lunar mission would cost almost eight hundred million dollars, not counting amortized development costs (and assuming the Orion CM isn't reused, but the bulk of the cost is the Altair anyway). Ares V rivals that in cost per launch, but nothing else does. Launch cost is not the dominant factor in the expense of exploration beyond LEO.

Yes, if we go with the Program of Record (Ares), it will founder under the weight of its own high cost. Jupiter is as affordable and sustainable as anything we're likely to actually get in its lift class without a huge breakthrough, and the use of propellant depots in Phase III encourages private development of low-cost LEO launch capability, also driving down the costs of existing launchers by increasing their flight rate.

A note: Jupiter's potential volumetric payload capacity (which is just as important as mass for many applications) is vast - much better than either Ares V or Not-Shuttle-C, and in a different world from Falcon. This could be useful for lots of things, including many that you simply cannot do at all by connecting pieces launched on smaller RLVs.

If we don't start exploring, where is the market for cheap RLVs going to come from? There isn't enough business right now to support one. Even Skylon, which benefits massively from prior government-funded technological development, would need to capture basically the entire global launch market just to make back the initial investment, and if the flight rate didn't increase, it would only be moderately cheaper per kg than a Falcon 9.

The ISS is going to be extended to at least 2020. That's basically a given, unless Obama does something spectacularly dumb. At that point you're starting to push the expected operational lifetimes of the original Russian modules, which form part of the station core and cannot be swapped out or replaced.

...

You know, sometimes I think NASA's HSF side should be put through a trial by fire, just wipe all the nonsense and legacy hardware away and start over. Then I realize that this is probably impossible both politically and in human terms, and at best would probably end up repeating the post-Saturn gap mistake. It's better to muddle on with what we have and try to fix it along the way.

...holy epic rant, Batman... maybe I should take myself a bit less seriously...

Consider, the actual change in energy of the Shuttle from ground to orbit is around 565 million newtons, yet the shuttle launch generates just shy of 5 Billion newtons to do that. Where does the other 4.5 billion newtons go? Mostly to heating air as the shuttle pushes it out of the way. In fact, half that energy is needed and gone in the first 90 seconds, just to get a lousy 10% of the way to orbit. What happens in that first 10%? Answer: We have to plow our way through 95% of the atmosphere.

Moon = no atmosphere, means a 80%+ savings in energy expended to reach orbit.

I'm sorry, but this is absolute nonsense.

In the first place, why are you using newtons as a unit of energy?

Low Earth orbit is about 7900 m/s. Launching from the equator, it's closer to 7500 m/s relative to the launch site because of the bonus from the rotation of the Earth. An ordinary launch vehicle will need over 9000 m/s to get to low Earth orbit. That includes combined drag and gravity losses of about 1500-2000 m/s total. So if the Earth had no atmosphere, AND was perfectly smooth so you could "orbit" on an equatorial maglev track, you'd only need maybe 20% less delta-V to do it. That helps the mass ratio disproportionately (5.4 versus about 11 for hydrolox SSTO, including the extra bonus from being able to use extremely efficient low-thrust engines at full vacuum efficiency), but the payload capacity is not a factor of eight better - more like a factor of two or three.

Doing away with the atmosphere by itself, but keeping the free-flight and altitude requirements, you still need high thrust, and thus lower Isp, though you can still get away with vacuum nozzles right off the pad. With vacuum nozzles on top of no drag, I'd guess the mass ratio for a hydrolox SSTO would end up around 8.

Low lunar orbit is less than 1900 m/s total, including gravity losses. That's a mass ratio of about 1.5 for a hydrolox SSTO, or 1.9 for a hypergolic one. That's where the big advantage comes from - lower gravity.

[TallDave]

Splitting water into hydrogen and oxygen is easy, very easy. So that does not cost much of anything at all.

Splitting water into hydrogen and ogyen and putting the results into a useful container is easy here on Earth where we're surrounded by a post-industrial civilization. On the Moon it will be hellishly expensive, because all your eq has to be lifted from Earth and function in a dusty vacuum. Getting the water out of the lunar surface itself will be difficult (are we looking at ~1% of a given volume being water?), then it has to be purified, etc. And if something breaks down, you can't exactly call a repairman. You'll need massive redundancy, and you'll need some way to power your lunar LOX factory.

I guess it boils down to: how much LOX do you have to produce before it masses more than the LOX factory, and how long will that take? Also, x amount of LOX delivered to orbit by rocket today is probably worth x * 2 delivered in a year or two by the factory (time value is high). The factory probably costs at least 1 MW to operate, too, which is a lot of solar panels...

Is it reasonable to think a 100 tons of factory and solar power gatherers can produce 200 tons of LOX on the Moon in less than a year? I am skeptical. The water appears to be either a thin layer spread over a large area (bad) or stuck in rocks (worse, because now you need a LOT more energy to free it).

And keep in mind: cheaper launches don't make this concept more viable, because it also gets cheaper to just lift fuel instead of a fuel factory.

[jnaujok]

Consider, the actual change in energy of the Shuttle from ground to orbit is around 565 million newtons, yet the shuttle launch generates just shy of 5 Billion newtons to do that. Where does the other 4.5 billion newtons go? Mostly to heating air as the shuttle pushes it out of the way. In fact, half that energy is needed and gone in the first 90 seconds, just to get a lousy 10% of the way to orbit. What happens in that first 10%? Answer: We have to plow our way through 95% of the atmosphere.

Moon = no atmosphere, means a 80%+ savings in energy expended to reach orbit.

I'm sorry, but this is absolute nonsense.

In the first place, why are you using newtons as a unit of energy?

Low Earth orbit is about 7900 m/s. Launching from the equator, it's closer to 7500 m/s relative to the launch site because of the bonus from the rotation of the Earth. An ordinary launch vehicle will need over 9000 m/s to get to low Earth orbit. That includes combined drag and gravity losses of about 1500-2000 m/s total. So if the Earth had no atmosphere, AND was perfectly smooth so you could "orbit" on an equatorial maglev track, you'd only need maybe 20% less delta-V to do it. That helps the mass ratio disproportionately (5.4 versus about 11 for hydrolox SSTO, including the extra bonus from being able to use extremely efficient low-thrust engines at full vacuum efficiency), but the payload capacity is not a factor of eight better - more like a factor of two or three.

I used newtons because I was looking for a quick and easy way to determine how much of the thrust of the vehicle was wasted compared to what was actually necessary. If you do the reverse math, taking the mass of the shuttle, and dividing by orbital velocity minus equatorial velocity (the exact calculation I did) you would have found that my delta-v's all lined up with your numbers (the actual delta-v from an equatorial launch was, IIRC, 7433 m/s)

However, since all the wikipedia pages, etc, show the SSME and SRB thrust in terms of newtons, I figured that it was just as good a way of showing velocity change, since, after all, it is a measure of acceleration of mass.

Calculating the total change in acceleration (the "jerk") of the shuttle is simple, just multiply it's 78,000 kilo dry weight by the orbital velocity. This, then, is the ideal launch to space. Were we able to just shoot it out of a cannon (something you can do on the moon, by the way) without an atmosphere to burn it to cinders, then it would take just over 500MN to put it into an orbit 333 km high (the orbit of the ISS).

Of course, a large part of getting it there is lifting all the fuel it takes to put it there as well, so this "back-of-the-envelope" calculation is not totally accurate. Yes, probably 75% of the launch mass ratio is used to lift the fuel that gets burned. That means a lower about a 10 to 1 advantage. But again, that's ignoring one fact.

If all we're sending up from the surface of the moon is cargo (not humans, for whom a 100G acceleration would be, uh, bad) then there's no reason not to use a cannon style launch. That means *no* fuel used lifting fuel to sub-orbital velocities.

And then I'm right back up to that 40-1 launch ratio.

And that's all thanks to no atmosphere.

Sorry for any typos, I strained my left hand and I'm hunt-and-pecking one-handed at the moment.

Update: Did the math, with a 2KM long "cannon", it would take a mere 58 metric tons of old-school black powder to put a space shuttle into a 320 km high lunar orbit (at 60g's of acceleration - cargo only, obviously). That sounds like a lot, but consider that it's the equivalent energy (released much more explosively) of 620 gallons of gasoline, and suddenly it doesn't seem like that much compared to the hundreds of tons of hydrogen (3x the energy of gasoline) that it takes to put the shuttle into orbit from the Earth.

The neat part is, if we make the "cannon" 30KM long, then it's a 4G shot, with 39 seconds of acceleration to go orbital from the moon. Using the same 620 gallons of gasoline.

(Yes, I know you need to add the oxygen. It's still diddly/squat compared to what we have to burn to get off the Earth.)

And to bring this all back on topic, the 175.5GJ it would take would also be much easier to apply by building a magnetic coil gun on the surface, driven by a Polywell fusion reactor....

[Skipjack]

As far as I know, NASA hasn't said RLVs are is impossible.

They have, multiple times, after the X-33 debacle. In fact, if you ask any NASA representative about RLVs, they will tell you this very thing.

Where did I say Skylon was the only concept available? Where did I say there was no place for an RLV in an exploration architecture? Stop misrepresenting me.

I am sorry, it was not my intention to missrepresent you. It was my intention to clarify my position in reference to your paragraph. I was not trying to imply that you did not know about other RLV- concepts.

VTOL SSTO concepts almost have to be all-rocket. This kills the performance because the mass fraction has to be insane.

I am not an expert for this, but there are people that are experts. Gary C. Hudson e.g.. Now, he obviously thinks that the concept is sound, as did Bono, whose designs Hudson refers to in this article.
http://www.spacefuture.com/archive/hist ... tems.shtml

Also, I do not think that the people behind the development of the DC-X/Y etc were all ignorant of the problems associated with such a design.
Given, this is an older article, but technology has only advanced since then.

However, I don't think they constitute a replacement for a heavy lifter. Exploration spacecraft cost more than their launchers, by a sizeable factor.

That may be true, but the corrent Constellation architecture does not require just a heavy lifter. Crews would not be launched on AresV but on AresI. They could be launched much more savely with an RLV, which could also support the station. What use is an expolation vehicle if you cant support it with a crew for a reasonable price?
Also, with an architecture that prefers infrastructure over speed of development, part of the exploration architecture could be fully reusable. E.g. a shuttle between Lunar Orbit and LEO, could be reusable and be refueled with fuel from the moon (with low enough cost to LEO also with fuel from earth). You said it yourself that the exploration vehicles are expensive. So why throw them away every time?

Personally I would make the shuttle between LEO and Lunar orbit nuclear powered, even.

Oh yes, and cost plus contracts encourage waste and should be done away with as soon as possible. Projects get huge numbers of engineers assigned to them just to drive up costs, and it actually slows down development because there's more coordination and dragging around dead weight going on than actual work...

I am glad that we agree on something.

That's less than irrelevant to the question of whether they should or not. As far as I can tell, you're arguing that they shouldn't.

It is not irrelevant because that is now NASA works and that is one reason why I want to pull the plug.

The fact is that chemical rocket technology is mature; it hasn't advanced all that much since Apollo, and it won't get substantially better than it is now no matter how long you wait.

That is not the only area where advancements can be made. Weight savings can be achieved by employing new technology for structural and TPS- materials, e.g. Newer, more lightweight computer technology also helps saving weight and space (sure it is not THAT much, but a bit).
Also, why has pretty much all development on the aerospike engines been stopped (other for a small college programme)?
Also, the shuttle was at least partially reusable. The constellation architecture wont be reusing anything (maybe refurbishing the Orion capsules, which will save close to nothing). DIRECT does not change this either.

You're not being consistent. You acknowledge the problem of lost know-how. You say "walk before we run". Yet you complain that the Constellation spacecraft aren't a vast enough technological leap over what we used last time we did something we're trying to relearn how to do in the first place?

Who said, we did it right the first time arround?
Apollo ultimately did not bring us anything in the long term. It was an achievement, but not worth repeating.
If we go to the moon again, we should do it better this time, not just bigger.

If we're not going to do exploration, there's not much point developing Jupiter, now is there?

And how are you planning on bringing crews and supplies to the ISS?
With the current planning the ISS will be destroyed - prematurely if you ask me. Why is that? Not because it would not be needed anymore, but because with the current plans, it will be to expensive to maintain it.

Six flights per year should get you below $5000/kg.

Still not cheap enough, though I do admit that it is an improvement.

That cost already includes amortized development cost. And it's got substantial margin built in (more than 30% IIRC).

Ah really, that is news to me. If so, that is not so bad at all. But as I said, that is news to me. Plus, full development has not even begun yet. It is just a study right now. As it has been with past NASA projects, predicted cost is usually way below the final cost.

Also, the costs for DIRECT are better founded than the costs for the Falcon 9; STS is a very well characterized system, and LC-39 is a known quantity in terms of operations, but Falcon 9 hasn't flown even once yet.

Falcon 9 hardware at least already exists and it will fly at the end of this, year or Q1 next year, something like that. DIRECT does not exist yet, other than on paper and (if I give you that) partially as the shuttle.
I think that drawing direct (no pun intended) conclusions from the performance of the shuttle to the future performance of DIRECT is premature.

Space industry veterans tend to feel that SpaceX hasn't really felt the bite of all the overhead that goes with operating a major launch business yet, and that once they do, their costs will go up, not down.

Yeah, of course they feel that way. They are protecting their corporate butts.

If DIRECT is selected, NASA and its OldSpace contractors will be able to make Jupiter fly, safely and routinely - and soon. SpaceX hasn't demonstrated anything yet as regards a launch vehicle the size of Falcon 9

Ahem, at much smaller budget: Full Falcon 9 flight- hardware at the cape, test Dragon hardware at the cape. Full Falcon 9 first and second stage ground tested. Launch in a few months from now.
All that has not cost NASA a single dime yet (other than the few millions for the resuply contract, which is also milestoned). How much has constellation cost so far? When is that going to fly? When is DIRECT going to fly?
So far SpaceX has achieved a lot more than what has been achieved by the OldSpace guys for constellation.
We will see whether whatever they will build will fly any time...

SpaceX, on the other hand, is a gamble even for ISS support. Depending on them for exploration missions is insane.

If SpaceX fails, it wont cost NASA more than a few million, maybe.
If Constellation fails, it will cost NASA many billions. Which risk is greater?

If we don't start exploring, where is the market for cheap RLVs going to come from? There isn't enough business right now to support one.

The typical chicken before the egg argument.
If you build it, they will come. Even suborbital flights have a market, if they are cheap enough, as we have learned recently.

[93143]

I used newtons because I was looking for a quick and easy way to determine how much of the thrust of the vehicle was wasted compared to what was actually necessary. If you do the reverse math, taking the mass of the shuttle, and dividing by orbital velocity minus equatorial velocity (the exact calculation I did) you would have found that my delta-v's all lined up with your numbers (the actual delta-v from an equatorial launch was, IIRC, 7433 m/s)

However, since all the wikipedia pages, etc, show the SSME and SRB thrust in terms of newtons, I figured that it was just as good a way of showing velocity change, since, after all, it is a measure of acceleration of mass.

No, you can't do that. Newtons are a measure of instantaneous force. They've got nothing to do with delta-V; you have to divide by mass and integrate over time to get that.

It looks like you did something resembling an integration at least. Why is your number still in newtons?

Calculating the total change in acceleration (the "jerk") of the shuttle is simple, just multiply it's 78,000 kilo dry weight by the orbital velocity. This, then, is the ideal launch to space. Were we able to just shoot it out of a cannon (something you can do on the moon, by the way) without an atmosphere to burn it to cinders, then it would take just over 500MN to put it into an orbit 333 km high (the orbit of the ISS).

That's not jerk, it's impulse. It's not in newtons; it's in newton-seconds. It's the time-integral of force, not the time derivative of acceleration.

Of course, a large part of getting it there is lifting all the fuel it takes to put it there as well, so this "back-of-the-envelope" calculation is not totally accurate. Yes, probably 75% of the launch mass ratio is used to lift the fuel that gets burned. That means a lower about a 10 to 1 advantage.

Actually this one fact explains pretty much the entire difference you attributed to atmosphere.

But again, that's ignoring one fact.

If all we're sending up from the surface of the moon is cargo (not humans, for whom a 100G acceleration would be, uh, bad) then there's no reason not to use a cannon style launch. That means *no* fuel used lifting fuel to sub-orbital velocities.

And then I'm right back up to that 40-1 launch ratio.

And that's all thanks to no atmosphere.

That wasn't what you said. You attributed the difference to drag.

Oddly enough, according to my calculations, 3500 mT for the Ares V lifting off the moon is probably about right, taking into account the high gravity losses due to the huge payload and low upper stage thrust. Mass ratio helps a lot.

By using a mass driver to put stuff in LLO, as compared with a Shuttle launch from Earth, you could do significantly better than 40:1 in terms of energy consumption per launch (in joules, FYI, or kg·m²/s²), which is what really matters. Naturally you'll still need either a circularization burn or a spacecraft to catch it before it slams into the other side of the moon...

[kunkmiester]

Assembling pieces in orbit is a major pain and should be avoided whenever possible. Remember, spacecraft costs dwarf launch costs even on today's rockets, so the less complex the spacecraft, the cheaper the mission. Monolithic ground-assembled hardware also reduces mission risk in a variety of ways.

part of this is the fact that weight savings are vital. pieces are going to be expensive when you spend millions shaving a few ounces off of it.

Lower launch costs allow more weight tolerance, which means more traditional engineering methods--which are more durable-- can be used.

The other issues you have with orbital assembly are smaller problems than you think. Part of the problem is that we simply haven't done much in-space assembly. The ISS is about the only thing we've put together in orbit, versus on earth. A design built to self-assemble in orbit remotely, without having to have astronauts doing EVAs would be emminently feasible, it's just that no one has worked it out. Add in the ability to make it more robust with fewer constraints on weight, and it gets even easier.

[DeltaV]

And to bring this all back on topic, the 175.5GJ it would take would also be much easier to apply by building a magnetic coil gun on the surface, driven by a Polywell fusion reactor....

Now we're getting close to Heinlein's "The Moon is a Harsh Mistress". Just a little more energy and you'd have a great weapon with which to rule the earth via kinetic impactors (containers filled with lunar soil/rocks). Who would be controlling this gun? If they were off-earth, you'd be in serious trouble, but if they were controlling it from earth you could solve the problem if you had enough F-22s...

[krenshala]

And the entire point of the F22 program was to replace the aging F15 program. I spent 10 years in the USAF, the vast majority at Langley AFB (HQ Air Combat Command, home of the 1st Fighter Wing ... F15s). The F15 entered service in Jan 1976. While it is a good plane, there are a lot of upgrades that it just is not able to take advantage of due to how old it is.

On top of that, I've read some articles that talk about the fact that the airframes of those planes are reaching a point where day-to-day flight stress is starting to lead to failures.

The F22 entered service just after I got out, but the first planes were scheduled to be delivered to the 1FW in early 1999. Everyone from the pilots to the ground crews were looking forward to it due to the improvements it would provide. I wouldn't be surprised if one of those improvements was maintenance costs. Keeping aging aircraft flying gets progressively more expensive. The shuttle program is an extreme example of this (though I admit a poor example from some aspects).

[DeltaV]

And the entire point of the F22 program was to replace the aging F15 program.

No argument from me on that:

http://www.avweb.com/avwebflash/news/US ... 521-1.html

Note the numbers; 700 F-15s to be replaced by (now) 187 F-22s. Cold war over or not, that's crazy.

[Skipjack]

Note the numbers; 700 F-15s to be replaced by (now) 187 F-22s

...and how many UAVs?

That said, I do agree that the F15s need replacement. I am surprised they are still in service at all.
Though I do have to wonder what all the other planes are good for then (F16, F18, F117)?
A matter of to many types of planes in service maybe?

[MSimon]

unless Obama does something spectacularly dumb.

Count on it.

[Skipjack]

Count on it.

So far he has not.