For my story i wonder about a situation where Mars try to gain independence from Earth. I specified that fusion ships should have around 100MW for 100 ton in order to maintain miliG acceleration for months. So a destroyer's cannons could fire 10MJ x-ray beams in every second for a while (laser focusation equipment more sensitive to heat than thrusters, a laser cannon could be damaged by a scale smaller one). Fleet around Mars counts 15 various kinds of ships, battleship too. I estimated 400 MJ in every second. As far as i know, Martian atmosphere swallows at most 10-20% of x-rays. Question, is it a bit plausible, that a reinforced government building (no energy shields) could withstand such a siege for a minute? After the fleet leave, orbital fighters still remain. Low orbital speed around Mars is 3km/s. So a squadron of fighters could do even more damage in a second with kinetic bombardment, than the fleet's cannons, but they cant attack continously (only with 1-2 MJ cannons). Would the thin atmosphere of Mars cause any significant trouble in guiding kinetic bombs at orbital speed?