kausikram k sayee wrote:
all the space vehicles today depend on combustion tech for launching
purposes . this technology which depends on an oxidiser and a fuel
gives just enough thrust to take a space vehicle from the earth surface
to the space against the gravity. now the speed and fuel capacityof
these vehicles will not be enough for long space missions ....so is
there a way by which we can use an alternate technology to launch space
vehicles without using combustion technology ...is there a way to over
come or anull the gravitational forces and make a body levitate ....?


That's an interesting question. There has been some talk about using
carbon nanotubes (CNTs) to create a space elevator, but unless the cost
of production for CNTs decreases a great deal, this will not be a
feasable option. I believe CNTs costs are on the order of $1000/kg.

If you are concerned with fuel depletion over a long duration, electric
propulsion (EP) is the way to go as it makes efficent use of propellant.
Though it is not very powerful, EP powering a spacecraft would be an
ideal choice for exploration missions or missions to the outer solar
system (Deep Space 1 and JIMO, for example). EP only operates in a
vacuum environment, so it will require a two-stage launch, most
likely the combustion engine you mention.

-Victor