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Using Fuel Depots Instead of Giant Rockets
EccentricAnomaly writes "The New York Times has a story about a leaked NASA study that showed it would cost $80 BIllion less and get astronauts to an asteroid sooner if NASA used fuel depots instead of developing a new rocket. According to the article, NASA's response to the leaked study is to start developing fuel depots in addition to continuing its new rocket program. Because, after all, who doesn't need more cool stuff."
there's no reason to visit Italy, Australia, Hawaii, or wherever it is that may be interesting to visit, when you have pictures of the place on the internet? That's the same thing right?
Now human experience counts for nothing?
Yes yes, I know, robots are better than internet pictures, still though, a virtual experience isn't the same, any more than madden 2012 is the same as playing NFL football.
We -certainly- have the energy, money, and will to do human space exploration, we're just currently wasting all 3 on other endeavors.
We could easily have both. Easily. Let me show you how:
NASA's budget: $18.724 billion (Fiscal Year 2011) (source: http://en.wikipedia.org/wiki/Budget_of_NASA)
Department of Defense's budget: $663.8
Which does NOT including Iraq and Afghanistan, which together are approximately $900 billion, and does NOT including the care for the approximately 33,000 wounded veterans those wars have produced... which is probably a few billion, but I couldn't find an easy source so let's just go with nothing. But remember it's there.
Adding those into DoD's budget gives: $1,563.8 billion. (source: http://en.wikipedia.org/wiki/Military_budget_of_the_United_States)
That means that DOD gets 83 times as much as NASA gets. They could reduce their budget by 1/83rd and double Nasa's budget.
A country needs defense. I get it. But seriously -- NASA is one of those organizations that, if your pour money into it, does AMAZING things. Things that give so much back to the scientific community -- things like computers, insulation, search and rescue, navigation, everything. So, so, so, so, so, so, so, so many technologies can be traced back to the space program... and while DoD are great inventors too, especially in medical treatment, materials, transportation... NASA gives so much back too and no brown people have to die.
Can't we just have a couple less B2 Stealth Bombers (B-52's bomb brown people just fine) and a couple less F-22's (F-15 Eagles still have never been defeated in combat) and GET THE FUCK TO MARS?
Check out my sci-fi book "Lacuna" at http://goo.gl/MVxX8
Fuel is a good candidate to launch with a high-g device, but a mass driver is not the most economical way to get it off the Earth. It is fairly easy to show that a pipe will cost less per foot than induction coils and a frigging huge power supply to feed it, for the same job of accelerating a projectile. Generally, these type of devices are called "hypervelocity guns", defined as when the muzzle velocity is hypersonic (ie more than Mach 5 or 1500 m/s). This is roughly twice the muzzle velocity of large military guns.
In 1993 I was the study manager at Boeing for using a large gun to deliver fuel to a depot, which then was used to send communications satellites to GEO. The savings was you needed 75% less conventional rocket to launch the satellite dry. Hypervelocity guns are not new, they have been used for ballistic and re-entry testing for about 40 years now. NASA owns several of them. Mainly they need scaling up and "industrializing" - setting them up for regular operations, rather than research use.
To reach the highest muzzle velocity, you want to use the lightest gas (Hydrogen), and heat it, so the speed of sound is as high as possible. Speed of sound is the same as speed of pressure waves in the gas, and when your projectile exceeds that speed, there is no way for the gas at the back end to affect the projectile any more, because it outruns the pressure waves. So the gun gets very inefficient at that point. To make hot hydrogen, it is easiest to store it at room temperature in pressure tanks, then run it through a heat exchanger before it gets to the barrel. There is nothing that goes "boom" like a small gun, it's closer to natural gas pipeline operations (in fact, we sourced the gun barrel from a pipeline maker in the study). Find a suitable mountain, such as Cayembe in Ecuador (the highest point on the equator, and the right slope), and put a 2 km long x 60 cm I.D. pipe pointing up. Load a 600 kg projectile about 4 meters long into it, and it will accelerate at 900 g's, and come out with a muzzle velocity of around 5600 m/s. You lose around 1 km/s of that to air drag, and then use an onboard rocket to finish getting to orbit. Net payload to orbit is around 100 kg, which does not sound like much, but if your launcher is at the equator, you can potentially launch 15 times a day to a single depot destination. Over the course of a year that comes to 550 tons (minus downtime for maintenance).
For launching people and delicate cargo, Hawaii is the best location. Assume a 20 km pipe x 10 m diameter, pushing a 500 ton vehicle. It works out the pressure in the barrel needs to be 2 atmospheres (200kPa, 30 psi). That gives you 3 g's acceleration, safe for humans and satellite parts. Muzzle velocity is 1100 m/s (Mach 3.6), which is not a huge fraction of orbit velocity, but a nice running start before you light up your on-board rocket. Given those starting conditions, a reuseable non-cryogenic rocket should have a payload of around 35 tons, which along with a 10 meter diameter should be plenty for any cargo or people you want to launch. This is the upper end of what you might want to build, for your first low-g cargo launcher you can go a lot smaller.