Massless particles and space travel?

Arent Massless particles (like photons and gluons) the key to space travel, they are forbidden to travel at anything but the speed of light and their weightless meaning they arent affected by gravity. I dont know how we could use them but i believe their the key to space travel.

anything with energy is affected by gravity. e=mc^2
light doesn't always travel at 3x10^8 m/s it can travel as slow as 17m/s (http://en.wikipedia.org/wiki/Slow_light)
the speed 3x10^8 m/s is only in a vacuum
sorry

Photons do have zero mass, but they are affected by gravity. Light bends as it passes massive objects. As for them being the "key to space travel," we humans are made of massive particles so we are still bound to travel less than the speed of light.

do u know tht 1) theory of relativity abandons accelaration of a partical from sublight speed to super light speed but dont say that the super light speeds are imposible. (partical orig. in super light speed may remain in that)
2) photons etc have zero rest mass not tht the have zero mass in gen.
3)at speed of light there is singularity in theory of relativity actuly we need experimenting and exploration at this speed

except that we are not maseless particle

well, you need to transform into those particles, travel and then reunite. It's very risky, if you know the concepts of entropy.

They have the concept of Solar Sails, to use the "Stellar Wind" from the sun and travel places. But It takes Ages for any kind of Momentum to be generated plus there's the factor of slowing down once you get up to speed. . .