What is the amount of energy required for a shuttle to leave earth and reach the moon?

Answer 1

The second answer erroneously uses the liftoff mass as the mass required to reach escape velocity. In fact the shuttle mass that actually reaches orbit is about 90,000 kg plus several thousand as payload. (The shuttle does not go beyond low earth orbit.) And as the first answer implies, we use rockets whose chemical energy is not readily derived from the power they deliver, which varies from 0 (exactly at liftoff, when V=0) to much more at high velocities. Finally, since rockets are used and the mass changes significantly throughout the ascent, you need to integrate the force, velocity and mass to obtain actual energy. So we can take answer 2's numbers, which assuming acceleration via a catapult or some other high-efficiency engine would deliver a 2 million kg load to escape velocity, or divide the numbers by about 20 and get the work needed for a 100000 kg shuttle to reach escape velocity via the same means. However, the chemical energy for rocket propulsion would be much more.
P.S. Answer 2's BTU figure is too high by a factor of 1000.

Answer 2

Well, the space shuttles weight about 2 million kg. The escape velocity of earth is 11.2 km/s. So the kinetic energy needed is
.5mv^2 = .5 * 2000000 kg * (11200 m/s)^2 = 1.25x10^14 J

This is about 35 million kW-hr, or 119 trillion BTUs. The same energy required for about 12 billion air conditioners.



Edit: In response to Kirchwey:

Eh, yeah, you're right. Pieces are continuously dropped and the fuel continuously runs out, but I mean, did you want to do all that integration? haha. If this was an engineering homework question and it gave the variables, then I would've considered that.

I just gave a general idea of the amount of energy needed. I probably should've chosen a mass somewhere in the middle, but oh well.

And actually, the BTUs are right. There are 3413 BTUs in a kW-h, and a kW-h is 3.6 MJ.

Answer 3

It's not amount energy, its amount of fuel.

Of course, there is certain amount of energy required to move mass 200 tons from Earth to Moon, but rockets do not operate this way.