Prior space projects have relied on a Mission concept of operations. That is you plan a mission ahead of time, with a detailed timeline of all the steps you expect to perform. Then the crew and ground controllers execute the plan. If deviations happen, corrective action is taken to return to the plan as much as possible. This concept works for a single mission in isolation with a well defined goal. Future projects will have multiple activities in multiple locations, with larger numbers of people involved and interactions between activities. So planning every step ahead of time in a linear fashion becomes difficult if not impossible. For cost reasons, you also want to reduce the large amount of planning and training that currently goes on relative to the actual doing.
For future projects, rather than planning everything in advance, one approach is to develop building blocks of tasks which can then be assembled as needed to reach a goal. As new feedback comes in from other tasks, the building blocks can be adjusted or replaced as needed. Changing plans may not be as efficient as carrying out a fully detailed plan made in advance, but the effort to make those advance plans may be larger than the efficiency loss. The ability to change or replace tasks, rather than a monolithic preplanned mission, also allows continuing operations to adapt and improve over time.
This task is the removal of human-made orbital debris, and, if possible, natural hazardous objects. Over time, debris will collide with itself and decay from drag. In the long term it will clean itself up, but in the short term the collisions will generate more hazardous size pieces, which is an unsatisfactory situation. Besides clean up of past debris, this task takes care of cleaning up future defunct, lost, or destroyed hardware. There are a number of methods which have been proposed to do this, none of which have been demonstrated yet:
- A "plasma-puffer", promoted by Daniel Gregory. That would use an arc discharge from a high altitude balloon to puff air upwards in the path of the junk, making it de-orbit faster.
- Ballistic puffer, which launches a projectile from a very large gun, that releases air or some other material in the path of the debris, having the same effect. The projectile is sub-orbital, so it does not add to the space junk problem.
- Lasers - zap the front of the debris, blasting off some of it, and slowing it down from the reaction.
- Drag devices - attach a large sail or conducting wire to the space junk and make it slow down faster
- Orbital tug - goes from orbit to orbit collecting junk. This requires high efficiency electric thrusters or the fuel used gets absurdly high.