A very interesting post by IEEE giving a tour of NASAs drone research labs.’ THey are doing work on large and small size UAV’s including areas of work such as environmental monitoring, collision avoidance, ways of reducing the cost of getting into orbit (Towed Glider Air-Launch Concept)
You can read the full post here
Some cool videos demonstrating the work
Ground collision avoidance
Towed Glider Air-Launch Concept