Landsat 5 TM and 7 ETM+ Specs
l185 kilometer swath width
l16 day repeat coverage (each)
–Synchronized for 8 day repeat coverage
l7 imaging bands* per sensor
–6 bands @ 30m resolution
l3 Visible & 1 Near Infrared (IR)
l2 Short-wave IR
l1 thermal IR band
– TM: @120m resolution
– ETM+: @60m resolution
–
l*ETM+ has one 15m Panchromatic Band
l
•Landsat observes the earth in a near polar orbit, and covers the same spot on earth every 16 days. The combination of Landsat 5 & 7 synchronized in a 8 day repeat cycle greatly increases the probability of full state coverage during the growing season.
•NASS uses seven Landsat TM/ETM+ bands, systematic correction, 30 meter resolution, path/row orientation, and nearest neighbor resampling.
•In many cases, it is very difficult to obtain full state cloud free imagery during the growing season, even with two Landsat satellites, therefore, losing one would be very detrimental to the program.  However, adding a third or more Landsat like sensors would greatly increase the odds of obtaining cloud free imagery during the growing season.
•The Landsat 7 covers the next adjacent path that the Landsat 5 covered the previous day, so that path 30 is observed on a Friday by Landsat 5, then on Saturday Landsat 7 observes adjacent path 31.
•The medium resolution Landsat platform provides excellent results not only because of the temporal coverage but because of spectral properties of the available bands, and how effective they are in separating land cover.