FA+
Shop
A moonbase in 8 years. Why even a stopped clock is still rig
13 years ago
A moonbase in 8 years. Why even a stopped clock is still right twice a day.
http://en.wikipedia.org/wiki/Newt_Gingrich
You all know this guy. This guy is an arsehole. If you're on this site, and even if you nominally vote republican, you can probably think of things you've heard about him which you find detestable. And yet the thing the news media in America has really jumped on him about, are his plans to build a permanant Moonbase by 2020. I'm not entirely sure that's justified. I think this may be one of those 'once every twelve hour' events when Mr Gingrich is right.
Disclaimer: By implying that he might be correct about the practical and economic feasibility of this concept, I am in not implying that he would actually follow through on his speach if ellected, or has the brains to actually follow through in an intelligent way, or is in fact an admirable or likable person in any way.
The problem:
People don't always understand the difference between science and engineering. In science there is often only One True Way of solving a problem. Relativity. The photoelectric effect. Evolution. Quantum Mechanics. (etc.) In engineering things don't work that way. Yes we use those rules, but we have a wide variety of choices in how we apply them. There are at least ten ways of building a bridge for example. And many of those applications are extremely non intuative.
The aerofoil is a simple application of newtonian physics. The jet engine is a simple application of the aerofoil. (I'm simplfying a bit here.) But considder how long it took for scientists and engineers to get from newtonian physics to the aerofoil, and from the aerofoil to the jet engine. The applications are obvious in hindsight, but were not in foresight, even to trained experts.
Which leads us back to Newt. In his speach he mentioned two things. Commercial space access, and low thrust electrical propulsion. Reading betwen the lines, I believe he's trying to talk about these three things:
http://en.wikipedia.org/wiki/Falcon_Heavy
http://en.wikipedia.org/wiki/Dragon.....8spacecraft%29
http://en.wikipedia.org/wiki/Variab.....oplasma_Rocket
So, if we were to combine these things in any order, and inventing no new spacecraft, what's the heaviest single spacecraft we could soft land on the moon? STOP HERE IF YOU WANT TO WORK IT OUT FOR YOURSELF!
Finished? Got your answer? Sure? Well, let's see if you're right. For everyone else, what would you guess?
5 tons?
10 tons?
20 tons?
50 tons?
Nope.
Try close to 300 tons - of which over 200 would be payload.
How the hell does that work?
Well you know that rockets operate in vacuum right? Sure you do. Everyone does. Even the New York Times does, at long last. But did you ever pause to think that one patch of vacuum in outer space is pretty much the same as any other patch of vacuum in outer space? Well it is. Any rocket that can work in earth orbit (or on the war there) can also work in Lunar orbit, and also hover the final few meters down to the lunar surface. It's all vacuum, and doesn't make the slightest bit of difference to the rocket.
Getting the rocket there is a bit trickier.
A Falcon-Heavy rocket is due to fly for the first time betwen 2013 and 2015. It's special because it uses a technolgy called Cross Feed, which means for the first few minutes all three lower stage engines are being fed by only the fuel in the outer two stages. The fuel in the middle 'core' stage is left untouched, until after two outer cores seperate. For complicated reasons involving the Rocket Equation, a special case, and algebra, this results in a massive increase in payload capacity. In fact, it gives the rocket more than enough to launch over 50 tons into orbit. This is more than twice as much as similar rockets, and is more than enough to push the empty Core stage (with some slight modifications) into low earth orbit.
This core stage can be refuelled in orbit by other Falcon-heavy flights. This has been done. The russians have been performing orbital fuel-transfer since the Salyut days in the late 70s. It would take 5 Falcon heavy flights to refuel the Core stage. The Core stage uses RP-1 (essentially kerosene) and liquid oxygen, both of which can be stored in space with (relative) ease due to their (relatively) high evaporation temperatures and the insulating properties of near perfect vacuum. The refueled core stage is now capable of dropping about 200 tons of cargo onto the moon's surface from low lunar orbit. (Which would be another 4 FH launches.)
The final piece of the puzzle is VASMIR. A high performance electric rocket. NASA is currently trialing the VX-200 prototype, with the intention of deploying the final VF-200 engine on the international space station. (Ironically, to replace the same kind of russian chemical rockets we were talking about earlier.) In rocket science, the term 'specific impulse' is similar to 'miles per gallon' for car owners. VASMIR has a specific impulse of 5000s. By contrast the SSME, one of the most efficient chemical engines ever built, only has a specific impulse of 450s. Just to be clear: the bigger the number the more efficient it is. For space applications VASMIR is by far the better engine.
It's been shown that a 15 ton VASMIR 'space tug' can take 34 tons from Earth orbit to the moon, and return itself to pick another cargo. Scaling things up we have a 275 ton tug carrying our 450 ton landing craft to lunar orbit. It would take about twenty days to get there, and after that the landing craft (with the FH Core stage at its heart) would use its low efficiency (304s) but high thrust to soft land about 200 tons onto the lunar surface. And this is where most of you came in.
So what has this cost us? One FH for the Core. Four for the cargo. Five for the Core's fuel. Two for the Tug. Three for the Tug's fuel. Twelve flights total. At $130 each, we're a tad over $1.5 billion for launch costs - or about 1/10th of one year of NASA's budget.
NASA's current plans involve the SLS, which is basically a rerun of the Saturn V, but without the latter's class. It comes with an R&D price tag of $40B, with initially a cost of $2-4B per launch - thanks to the millstone around NASA's neck that is SLC-39.
Now the $1.5B cost about doesn't cover the R&D and construction costs of the tug, or the lunar cargo - but since we're saving $40B, and FH is almost paid for right now, and increased weight tends to bring the cost down (make it heavier is a simple way to solve engineering problems) I think we can afford to reduce both to a line item. Say $30 billion?
Is this really a good idea? Is it throughly checked? Is it the best we could do?
The first is a political decision, but I personally think a lunar base is a really good idea. But no the the other two. The DeltaV values are acurate, as are statements about storage, but I've no idea if the Falcon-Heavy core stage posses the throattling capacity to perform this mission. In fact it almost certainly doesn't. I simply calculated the maximum cargo it could accelerate through the required DeltaV from Lunar Orbit to the Surface. Soft landing cargo in 200 tons chunks is most certainly NOT the best we can do!
But it certainly has merits over returning to a 50 year old concept; whose only merit at the time was that it was fast. America can do better. And it should.
Can America do this? I don't know. I hope so.
Can Gingrich do this? I really hope I never have to find out.
Hopefully I've given you a glimpse of what might be done when we remember than engineering and science are two entirely different things, and that while they may guide each other, they do not truly limit each other unless we let them.
http://en.wikipedia.org/wiki/Newt_Gingrich
You all know this guy. This guy is an arsehole. If you're on this site, and even if you nominally vote republican, you can probably think of things you've heard about him which you find detestable. And yet the thing the news media in America has really jumped on him about, are his plans to build a permanant Moonbase by 2020. I'm not entirely sure that's justified. I think this may be one of those 'once every twelve hour' events when Mr Gingrich is right.
Disclaimer: By implying that he might be correct about the practical and economic feasibility of this concept, I am in not implying that he would actually follow through on his speach if ellected, or has the brains to actually follow through in an intelligent way, or is in fact an admirable or likable person in any way.
The problem:
People don't always understand the difference between science and engineering. In science there is often only One True Way of solving a problem. Relativity. The photoelectric effect. Evolution. Quantum Mechanics. (etc.) In engineering things don't work that way. Yes we use those rules, but we have a wide variety of choices in how we apply them. There are at least ten ways of building a bridge for example. And many of those applications are extremely non intuative.
The aerofoil is a simple application of newtonian physics. The jet engine is a simple application of the aerofoil. (I'm simplfying a bit here.) But considder how long it took for scientists and engineers to get from newtonian physics to the aerofoil, and from the aerofoil to the jet engine. The applications are obvious in hindsight, but were not in foresight, even to trained experts.
Which leads us back to Newt. In his speach he mentioned two things. Commercial space access, and low thrust electrical propulsion. Reading betwen the lines, I believe he's trying to talk about these three things:
http://en.wikipedia.org/wiki/Falcon_Heavy
http://en.wikipedia.org/wiki/Dragon.....8spacecraft%29
http://en.wikipedia.org/wiki/Variab.....oplasma_Rocket
So, if we were to combine these things in any order, and inventing no new spacecraft, what's the heaviest single spacecraft we could soft land on the moon? STOP HERE IF YOU WANT TO WORK IT OUT FOR YOURSELF!
Finished? Got your answer? Sure? Well, let's see if you're right. For everyone else, what would you guess?
5 tons?
10 tons?
20 tons?
50 tons?
Nope.
Try close to 300 tons - of which over 200 would be payload.
How the hell does that work?
Well you know that rockets operate in vacuum right? Sure you do. Everyone does. Even the New York Times does, at long last. But did you ever pause to think that one patch of vacuum in outer space is pretty much the same as any other patch of vacuum in outer space? Well it is. Any rocket that can work in earth orbit (or on the war there) can also work in Lunar orbit, and also hover the final few meters down to the lunar surface. It's all vacuum, and doesn't make the slightest bit of difference to the rocket.
Getting the rocket there is a bit trickier.
A Falcon-Heavy rocket is due to fly for the first time betwen 2013 and 2015. It's special because it uses a technolgy called Cross Feed, which means for the first few minutes all three lower stage engines are being fed by only the fuel in the outer two stages. The fuel in the middle 'core' stage is left untouched, until after two outer cores seperate. For complicated reasons involving the Rocket Equation, a special case, and algebra, this results in a massive increase in payload capacity. In fact, it gives the rocket more than enough to launch over 50 tons into orbit. This is more than twice as much as similar rockets, and is more than enough to push the empty Core stage (with some slight modifications) into low earth orbit.
This core stage can be refuelled in orbit by other Falcon-heavy flights. This has been done. The russians have been performing orbital fuel-transfer since the Salyut days in the late 70s. It would take 5 Falcon heavy flights to refuel the Core stage. The Core stage uses RP-1 (essentially kerosene) and liquid oxygen, both of which can be stored in space with (relative) ease due to their (relatively) high evaporation temperatures and the insulating properties of near perfect vacuum. The refueled core stage is now capable of dropping about 200 tons of cargo onto the moon's surface from low lunar orbit. (Which would be another 4 FH launches.)
The final piece of the puzzle is VASMIR. A high performance electric rocket. NASA is currently trialing the VX-200 prototype, with the intention of deploying the final VF-200 engine on the international space station. (Ironically, to replace the same kind of russian chemical rockets we were talking about earlier.) In rocket science, the term 'specific impulse' is similar to 'miles per gallon' for car owners. VASMIR has a specific impulse of 5000s. By contrast the SSME, one of the most efficient chemical engines ever built, only has a specific impulse of 450s. Just to be clear: the bigger the number the more efficient it is. For space applications VASMIR is by far the better engine.
It's been shown that a 15 ton VASMIR 'space tug' can take 34 tons from Earth orbit to the moon, and return itself to pick another cargo. Scaling things up we have a 275 ton tug carrying our 450 ton landing craft to lunar orbit. It would take about twenty days to get there, and after that the landing craft (with the FH Core stage at its heart) would use its low efficiency (304s) but high thrust to soft land about 200 tons onto the lunar surface. And this is where most of you came in.
So what has this cost us? One FH for the Core. Four for the cargo. Five for the Core's fuel. Two for the Tug. Three for the Tug's fuel. Twelve flights total. At $130 each, we're a tad over $1.5 billion for launch costs - or about 1/10th of one year of NASA's budget.
NASA's current plans involve the SLS, which is basically a rerun of the Saturn V, but without the latter's class. It comes with an R&D price tag of $40B, with initially a cost of $2-4B per launch - thanks to the millstone around NASA's neck that is SLC-39.
Now the $1.5B cost about doesn't cover the R&D and construction costs of the tug, or the lunar cargo - but since we're saving $40B, and FH is almost paid for right now, and increased weight tends to bring the cost down (make it heavier is a simple way to solve engineering problems) I think we can afford to reduce both to a line item. Say $30 billion?
Is this really a good idea? Is it throughly checked? Is it the best we could do?
The first is a political decision, but I personally think a lunar base is a really good idea. But no the the other two. The DeltaV values are acurate, as are statements about storage, but I've no idea if the Falcon-Heavy core stage posses the throattling capacity to perform this mission. In fact it almost certainly doesn't. I simply calculated the maximum cargo it could accelerate through the required DeltaV from Lunar Orbit to the Surface. Soft landing cargo in 200 tons chunks is most certainly NOT the best we can do!
But it certainly has merits over returning to a 50 year old concept; whose only merit at the time was that it was fast. America can do better. And it should.
Can America do this? I don't know. I hope so.
Can Gingrich do this? I really hope I never have to find out.
Hopefully I've given you a glimpse of what might be done when we remember than engineering and science are two entirely different things, and that while they may guide each other, they do not truly limit each other unless we let them.
The depressing part is that we probably need colonies on planets other than Earth to ensure humanity survives as a species. Besides, the economic potential is massive.
NASA probably would sincerely like for him to slow down, but I boubt that's going to happen, and as long as he controls the company every penny of R&D will be spent on reducing launch costs.