Come on folks--surveillance satellites can, just like any other satellites, come in a couple of flavors: high-orbit geosynchronous or geostationary, and low-orbit. The high-flyers/geostat/geosync are great for getting a marginal picture of the same area--great for tracking hurricanes and himmicanes. The low-flyers are great for taking some sorda-detailed pictures every few hours or days, depending on how many birds you have flying.
On the other hand, survaillance aircraft have their varioius advantages/disadvantage:
The Global Hawk/UAVs have maybe 12 to 24 hour "dwell time" over a target area, but they, in reality, have serious operational difficulties--marginal payload capabilities/reliability/etc (unless you talk to someone trying to sell you some).
The now-retired SR-71 was fast, but had lousy dwell time--maybe 30 minutes over target before you had to go home.
The venerable U-2 (yes, they still fly them) still provides "reasonable" dwell time--about 12 hours total flight time, and still provides some of the best/most diverse recon capabilities around, but requires a lot of inconvenient life support for the pilot.
My concern--being such a noted authority on everything--is that a lightweight, stay in the air forever recon plane as proposed will not have anywhere near the mulit-spectral recon capability that a U-2 presently has, and will prove as worthless as the Global Hawk.