February marked the 25 year anniversary of the Shuttle Radar Topography Mission (SRTM) which gave us the then revolutionary global1 high resolution2 elevation dataset of the same name. What an achievement!
SRTM travelled on board of Space Shuttle Endeavour on the STS3-99 mission in February 2000. Technically, it was a single-pass interferometric C-band SAR4 system with the second antenna placed on a roughly 60 meter long mast that had to be deployed from the Shuttle’s transport bay. During data capture in an orbit 233 km above the Earth, the crew had to change data recording tapes every 30 minutes. More than 200 hours of data collection was done through 11 days of flight resulting in more than 12 terabytes of data on the shape of the Earth surface.
Initially, SRTM digital elevation models were offered at 1-arcsecond resolution over the USA and at 3-arcsecond resolution in the rest of the world. I still remember from working with SRTM data that these resolutions equate to approximately 30 meters and 90 meters, respectively, at the equator5. Today improved, e.g. void-filled, SRTM data is available globally at 1-arcsecond resolution.
To celebrate the occasion, there is an interesting look back on SRTM by NASA as well as one by the DLR from which the video below is sourced (in German, but English subtitles are available).
Enjoy!