Each and every every now and then, the ISS calls for a spice up to counteract orbital decay and care for its altitude. Whilst the ISS is provided with its personal thrusters, they aren’t enough for primary reboosts because of restricted gas capability, decrease energy, and the wish to maintain onboard assets for different important operations (like orientation keep an eye on and house junk avoidance). So as a substitute, docked spacecraft are used to supply those exterior boosts. Those spacecraft, particularly designed for such duties, convey their very own gas, minimizing the stress on ISS assets, and feature extra robust engines for enabling those really extensive orbital changes.
All this mentioned, Russia’s Development is lately the one spacecraft formally sanctioned for this job, because of its confirmed capacity and compatibility with the ISS. Whilst different spacecraft like Northrop Grumman’s Cygnus and Russia’s Zvezda might be tailored for reboost tasks, they don’t seem to be sanctioned for this function and will require further measures, reminiscent of Development having to gas Zvezda for the duty. NASA doesn’t love this case, which is why it has carried out reboost assessments with Cygnus.