10
votes
Hypothetics: let's say it takes 1/100 of the current fuel to take a spacecraft out of Earth's atmosphere. What happens?
This is obviously a thought-experiment, but maybe an interesting one. Let's say we get a super-efficient, eco-friendly alternative fuel that can do whatever rocket fuel does now with 1/100 of the cost, 1/100 of volume and 100% more efficiency. What does it change in the short term?
I think primarily we'd see an explosion in space based industries like orbital networks for phone and internet access instead of undersea fiber optic cables, lots of startups trying to go to the asteroid belt for mining, and speculation in orbital power stations.
Space tourism would be reserved for the very rich, but not the obscenely rich. You'd probably see celebrities and well to do business people taking trips into orbit for vacation. Maybe there'd even be a market for an orbital hotel for the ridiculously wealthy.
Unfortunately the tragedy of the commons would eventually take place though. The cost barrier to entry orbit would mean that all kinds of private entities and governments, many of which more responsible organizations like NASA and the FAA have no control over would start launching all kinds of things into orbit, and it would become quite cluttered very quickly, leading to Kessler Syndrome almost becoming an inevitability. Governments would likely have to invest quite a bit of money into orbital hygiene programs to track and clean up debris and obsolete equipment.
I don't think that colonization would become widespread. There just aren't a whole lot of advantages to living in space. I could see there being waystations in the asteroid belt eventually filled with workers that managed and monitored mining operations (very difficult to control mining robots for delicate procedures with an hour long delay at the speed of light). All in all, I don't think the average person would notice much of a difference besides high speed internet access being available literally everywhere in the world for a reasonable cost, and the cost of goods that require precious metals like gold and platinum going down in cost due to their widespread availability in the asteroid belt.
There would probably be some implications for commercial aviation as well depending on how this magic technology works.
And, on a sadder note, probably a lot of headway made towards weaponizing space through capacity for orbital bombardments and the means to counteract them.
Also we can't understate the value of having lots more and cheaper satellite coverage and imaging. This means both military (spy satellites) and civilian uses for monitoring sensitive ecosystems, getting real time information and telemetry, etc. You can get more reliable weather forecasting and really refine models. You can also have satellites with shorter operational life-spans and that means you can more regularly send up the latest and greatest technology with less need to worry about long-long-long term reliability. You'd functionally be increasing the computing power up there and it's hard to say how much of a long term impact that would have.
Basically, you'd be increasing specific impulse a hundredfold. If keeping the same fraction of propellant to mass as today, you'd also be increasing your delta-V budget a hundredfold.
It takes 10-15 km/s of delta-V to leave Earth (it depends on where you want to get). A hundred times that brings you up to 1000-1500 km/s, which is ridiculously high and pretty much torchship territory.
That would change a lot of things, very fast, because right now? We need to use most of the mass of the rocket for fuel to get to orbit. We need stages to get anywhere. Every gram counts.
The price for boosting mass to orbit would become dirt cheap. Getting to Mars wouldn't require a multi-month trip anymore, as you could get there and back within the week (a "conservative" 250 km/s would be enough to cover an AU in seven days). Interstellar travel would be still unfeasible, but the Solar System would become our backyard.
Even if space is far from welcoming, I can still see a lot of people jumping to the opportunity of leaving Earth, and they would be able to do that.
The other side of the same coin is rockets with the same payload and delta-v capabilities but with vastly smaller propellant tanks. They could go from being most of the rocket to being a small part, like the fuel tank on a car.
There would probably be a wide range of rockets between those
twothree extremes: small "cars" for getting around in planetary orbit*; large tank, small/medium payload "jets" for fast travel over long distances; and slow, large payload freighters.(*or for those people who think it's fun to cross the ocean in a glorified lifeboat)
Slightly unrelated, but why do rockets propel straight up instead of taking off like a plane? Wouldn't the gradual climb be less taxing for fuel and require less weight/payload drop at the edge of the atmosphere? It would also set the ship up for a more gradual and controlled re-entry if it had the capability of flying instead of dead-falling.
Basically it's because getting to orbit involves a lot more than just getting above the atmosphere. In order to stay in space, a ship has to be going fast enough horizontally that it moves over the horizon faster than it falls back down. The speed needed to do this is about 8km/s, so it's basically impossible to reach unless you're out of the atmosphere to avoid drag. That's why rockets make what's called a gravity turn, and go from vertical to horizontal once they reach sufficient altitude.
You can only get out of the atmosphere with a rocket, since it supplies its own oxygen, whereas jets are airbreathing. Because the rocket supplies its own oxygen, it's of no benefit to stay in the atmosphere any longer than you need to be, since it's not doing anything but dragging you down.
As for reentry, even in capsules it's actually pretty controlled, or more than it looks like anyway. It's just that orbital velocities are about Mach 25, so once you're low enough that aerodynamics become relevant, drag is going to make you slow down very fast.
With the risk of sounding really dumb, maybe that's because space is UP.