So someone posted this on a forum and I wrote this piece for it:
"That guy is a Strategic Platform Operator/Overwatch Kill Mission unit, otherwise known as a SPOOKM. Due to the ridiculous policies of mid-21st century disarmament treaties, there is a UN-enforced ban on all teleoperated automated orbit-to-ground weapons, but small arms orbit-to-ground weapons are permitted, because they ensure accountability. Thus, the Spook'em is a gunner waiting in constant EVA on a sub-orbital ELINT/K platform for any kill order that might come, and then uses his STG MIKR rail rifle to put a big hole into whatever little hideout the terrorists have crawled out of. They are also called upon to neutralize low-flying enemy drones or overhead satellites and suborbital insertion pods, as well as general sub-orbital support over hot zones.
Spook'ems operate their platforms in groups of three and have 8-hour EVA shifts. They are trained in long-range marksmanship, low-orbit and EVA operations and close-quarters combat, for the surprisingly likely event that their platform might come under assault by a close-flying enemy stratellite or GTO kill-drone. Their tours only last for a few of years (during which they are constantly on-station), after which time most of them retire to a fat pension fund and however many years they have left before the cancer takes them."