Friday, March 29, 2013

What you should know about Landsat 8

Landsat 8 launched successfully and is orbiting the earth, so it's time to get ready to work with all this cool data!  I need to acknowledge that at the time this blog post was written Landsat 8 is not officially "Landsat 8," it is called the "Landsat Data Continuity Mission (LDCM)."  Once testing is complete (scheduled for May 30th), NASA will pass control to USGS and we will have an "operational" satellite whose official name is "Landsat 8!"

From an end user's perspective one of the most important things to keep in mind is that the band configuration for Landsat 8 (LDCM) is different from the Landat TM and ETM+ missions as Landsat 8 added two new bands.  Want to make a natural color composite from Landsat 8?  It will now be R-G-B = 4-3-2 (for Landsat 4,5, and 7 it was 3-2-1).  The USGS has a very helpful FAQ page listing the band numbers and wavelengths for all the Landsat missions.  There is another handy USGS page that displays the band combinations of Landsat 8 to Landsat 7 (see graphic below)

Source: NASA

Landsat 8 will be 12-bit data, compared to the 8-bit data used for previous Landsat missions.  Pixel values will now range from 0-4095 (4096 possible values) for Landsat 8, as compared to 0-255 (256 possible values) for the previous missions.  This should make it easier to distinguish features that are spectrally similar and shadow penetration will be much improved.

Because Landsat 8 is not yet officially operational you cannot download scenes from sites like GloVis just yet, but you can download a sample dataset to play around with courtesy of the USGS.