1. NOAA/TIROS-N

2 satellites with daily coverage

AVHRR

5 channels from visible to thermal IR

2. Landsat

MSS

5 visible channels, 80 m resolution

TM

7 band (6 visible, 1 thermal IR), 30 m resolution

3. SPOT

multiple visible channels, 20 m resolution, 10 m resolution panchromatic