France: European Space Agency’s (ESA) ERS-2 and Envisat satellites have been paired up again – for the last time. Data from this final duet are generating 3D models of glaciers and low-lying coastal areas.
ESA engineers configured the first tandem mission during September 2007 to February 2008, and second d during November 23, 2008 to January 27, 2009; to ensure that the satellites both acquire data over the same area just 28 minutes apart. ESA paired the two satellites together to help improve their understanding about the Earth.
The 2010 tandem campaign continues the work of the satellites’ earlier joint efforts on measuring the speed of fast-moving glaciers, detecting land-ice motion and developing elevation models over flat terrain.
Their third pairing took place from February to April 2010 with both satellites acquiring radar data for the first time over Antarctica’s coastal glaciers and ice shelves just 30 minutes apart.
By combining their synthetic aperture radar (SAR) tandem data, acquired over the same area within a short time, changes that occurred quickly can be detected. Some fast-moving glaciers, for instance, move more than 200metre/year and can move as much as 1 cm in 30 minutes.
This technique, known as SAR interferometry, or InSAR, has proven to be very useful for monitoring glaciers, detecting surface deformation and creating digital elevation models (DEMs).
A fourth campaign, from July to October 2010, focused on low-lying coastal areas, such as New Orleans in USA and the Po River Mouth in Italy. This information will be used for various applications in many different fields, in particular for creating accurate DEMs of coastal areas that could be used to help manage floods.
As planned, the fourth campaign ended on 22 October, the day in which Envisat was placed into a new orbit (from about 800 km to about 783 km) to minimise fuel usage and extend its life by three years. As a consequence, Envisat and ERS-2 are now in two different orbits and can no longer acquire tandem SAR data.
ESA will make the datasets from this final joint flight available to everyone as soon as they are processed and validated.