Re:An extrasolar world covered in water?
by perihelions on Thursday September 01, 2022 @12:45PM
(#32679123)
It'd just be 13 km/s to low orbit (or 19 km/s to escape), which isn't really that much for small payloads -- New Horizons had a total of 17 km/s delta-v. You don't even need to look at space elevators or fission or fusion launch systems, all of which are probably viable on first principles.
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Re:An extrasolar world covered in water?
by vikingerik on Thursday September 01, 2022 @04:07PM
(#32682352)
That orbit or escape velocity really is that much. The rocket equation is exponential, such that even a small change in the required speed means a large change in requirements. The difference between Earth's escape velocity of 11 km/s and this planet's of 19 is actually quite huge. Imagine you build an 11 km/s rocket as you would on Earth... to get it off this other planet, first you have to accelerate that rocket and all its fuel to 8 km/s.
The rocket equation is Δv = Ve ln (m0 / m1), where Ve is exhaust velocity, m0 is payload mass, m1 is mass including fuel. To get 19/11 as much Δv, you need a fuel/mass ratio of e^(19/11) = 5.6 times greater.