how is it possible to fuel a spaceship for all those years it spends in space?

Question

the recent rocket Dawn wont reach its first destination till 2011 and the second destination 2015! How do they keep it fueled?

Answer 1

A. they only use a little fuel normally
B. the Dawn spacecraft uses the revolutionary new ion drive which uses a tiny bit of fuel.

Orbital Mechanics are physics in action and are complex to figure out (requiring calculus), but pretty steady and well known.

Most of the fuel a spacecraft uses are burnt up just getting it into low earth orbit. After that the major thrust unit is gravity. The dawn spacecraft is going to spend a few days switching to a higher orbit and then leaving the earth to make a Mars fly by, a trip around the sun, and then on to Ceres and Vesta.

There is a special orbital path that lets the spacecraft steal some of the orbital speed of the planet to boost the spacecraft. This is how all of our deep space probes and our Mars probes got out there. Voyager had to circle the Earth, Venus, the Sun, Mars, and then it went on a fly by to Jupiter, Saturn and beyond. Until the New Horizon probe was launched it was the fastest man made object ever.

The new ion engine is an electrical engine that uses a tiny bit of material that it ionizes and expels out the rear. The acceleration is minor, but in space with almost no resistance it mounts up quickly. Still the Dawn mission is expected to reach Mars in 1.5 years. Then it will go on to the asteroid belt; and the asteroids Ceres and Vesta of 2009.

It takes a while for spacecraft to get out into deep space and we don’t use very much rocket power to do it. Galileo was launched from the bay of the Space Shuttle (October 18, 1989 by the Space Shuttle Atlantis on the STS-34 http://en.wikipedia.org/wiki/Galileo_%28spacecraft%29) with a small booster rocket and it went to Jupiter.

According to Wikipedia: http://en.wikipedia.org/wiki/Galileo_%28spacecraft%29#Propulsion
“The Propulsion Subsystem consisted of a 400 N main engine and twelve 10 N thrusters together with propellant, storage and pressurizing tanks, and associated plumbing. The fuel for the system was 925 kg of monomethyl hydrazine and nitrogen tetroxide. Two separate tanks held another 7 kg of helium pressurant. The Propulsion Subsystem was developed and built by Daimler Benz Aero Space AG (DASA) (formerly Messerschmitt–Bölkow–Blohm (MBB)) and provided by Germany, the major international partner in Project Galileo.” )A newton is the amount of force required to accelerate a body with a mass of one kilogram at a rate of one metre per second squared: http://en.wikipedia.org/wiki/Newton).

The helium was used to make course corrections that put it into the new orbits I was talking about. The engine only got it out of low earth orbit.

For more on the Dawn Mission: http://en.wikipedia.org/wiki/Dawn_Mission

Answer 2

They don't need fuel to move once they're away from large bodies and have been accelerated to the desired speed. They only require fuel to change direction or speed (known collectively as velocity) in the absence of another large body that could do it for them.

Answer 3

Once a spaceship is in outer space it becomes self propelled as the normal movements of the planets and the universe are whats actually moving.

Answer 4

After you give it a start in the right direction it just keeps going and doesn't need any fuel.

Answer 5

gravitation pulls....orbiting planets?