Today NASA successfully launched the new Landsat satellite. This is very good news for anyone involved in Earth visualization. The background of Landsat and what is being emphasized by NASA and USGS is the continuity of coverage with previous satellites of the Landsat series – the name LDCM, Landsat Data Continuity Mission, indicates that as well.
But beyond that there are a few other things about Landsat that make it special and a unique source of data for visualization purposes:
- Landsat data is quite unique as a fee, high resolution image source. Starting with the GeoCover dataset and later being extended to all data from the satellites the Landsat program being freely accessible and usable is the only high resolution image data source i know of where this applies. And according to the USGS announcements this will continue to be so for Landsat 8. I cannot refrain from pointing out here that to my knowledge there is no European operated earth observation satellite (with any kind of sensor, not only optical imagery) with a similar policy.
- Landsat is also quite unique in offering three spectral channels that resemble human color perception. This allows producing accurate color images. In contrast most other high resolution satellite sensors lack a blue color channel.
The question is of course why this launch is anything special if it is just for continuing work of previous satellites? First Landsat 8 contains several improvements over the previous satellites: It has two new spectral channels (among them a short wave blue channel that might be useful for improving color accuracy) and it is supposed to provide better quality (i.e. lower noise) data. But more importantly the previous Landsat satellites have been hampered by various problems recently: Landsat 5 which has been operating way longer than originally planned has only supplied few images in recent years before failing completely in end 2011. Landsat 7 which is still operational had an instrument damage in 2003 that severely affects the data returned, especially for visualization purposes. In sum: data supplied by Landsat in the last few years is in fact only a shadow of what it was supposed to be. Most Landsat images you see today either in form of individual scenes or mosaics are from when Landsat 7 was fully working in 1999-2002. There is hope now that these conditions are returning when Landsat 8 gets operational in summer this year.
A few images from the launch from NASA: