The latest presentation to the Future In-Space Operations (FISO) study group is now posted in the FISO Working Group Presentations Archive. There are slides and a video in a zip file plus an  audio file  (mp3) available for the talk, Minimoons: New Prospective Targets for Human Exploration, Bill Bottke, SWRI Boulder – Jan.15.14

Occasionally, near earth asteroids are captured temporarily in orbits around earth. Bottke calls these Minimoons:

TheEarth-Sun Lagrange points minimum areas are of particular interest.

The objects can last for just one simple orbit –

Or for many complex orbits:

Lifetimes in the earth region can span many years:

They estimate a couple of dozen such Minimoons are in orbit around earth at any given time:

Bottke goes on to  discuss ideas for improving the detection of Minimoons and for targeting them for exploratory missions, including human missions.