Unfortunately all of the bodies is KSP are on rails. The force your ship puts on them has no effect on them. If real physics were used, the force it would take would depend on what you consider "moving it", because even the smallest force would move the body a small amount. Also, it would be a matter of energy required to move the body, rather than delta v. In terms of energy, it would take (1/2)(1.24 x 10^17)(274)^2 or 4.65 x 10^21 joules of energy minimum to completely stop gilly relative to eve and have it come crashing straight in. Isp * units of fuel * 10000 = joules of kinetic energy a ship can gain. Conclusion : It would take 4.65 x 10^14 or 4.65 hundred million million units of fuel to stop gilly's orbit. Sorry, not happening anytime soon Hope this was at least informative Peter