Previous mission 

Courtesy of NASA/JPL
The Space Shuttle launch

In 1994, two missions known as SIR-C/X-SAR (Shuttle Imaging Radar-C/X-Synthetic Aperture Radar), designed and carried on by NASA, DLR and ASI (the American, German and Italian Space Agencies) took place in April and October. During both missions, the SIR-C/X-SAR system aboard the Space Shuttle has the following characteristics:
Bands / frequencies (GHz) L, C, X/ 1.25, 5.3, 9.6

L and C bands – quadruple

X band – VV polarization

Incidence angle variable from 15 to 55
Resolution 30m X 30m

The first SIR-C/X-SAR mission, aboard STS-59 (Space Transportation System-59), and launched on the 9th April 1994, collected 65 hours of data during the ten days of mission, roughly corresponding to 66 millions square kilometers of observed Earth surface. The mission returned 47 terabits of data, the equivalent of 30.000 encyclopaedia volumes. The STS –59 achieved 100% of the SIR-C/X-SAR science objectives. In addition to taking high resolution data of all the planned sites, the scientific team was able to adjust the time-line in order to observe some phenomena in the very right moment they occurred on the Earth. For example, the inundation in the mid-west of the U.S. and in Germany, or Cyclone Odille as it formed in the Pacific Ocean or the thaw in Canada in spring.

Pinatubo1 Pinatubo2

Mount Pinatubo, Aprile 14, 1994    

     Mount Pinatubo, Ottobre 5, 1994
     Courtesy of NASA/JPL

The second SIR-C/X-SAR mission took place in October 1994 with the same payload aboard STS-68. One of the most important objectives of the second flight was to acquire images of the same area of the first one to compare them, in particular, the Pinatubo mountain and volcanoes on Galapagos islands, the Etna and other areas where volcanic eruptions or other important phenomena had occurred.

Isabela Isabela, Galapagos Islands, 3D model

Another great success of the SIR-C/X-SAR mission was to test a new image from satellite elaboration technique known as interferometry. Exploiting continuos passages of the antenna on the same area we can generate a DEM (Digital Elevation Model) of the observed area and to realise a high precision topographic map , just if the orbits are repeated with sufficient precision. In addition, it is possible to compare the images obtained by successive passages on the same site to survey variations. Both the SIR-C/X-SAR missions, then had a great success and started the many scientific missions whose main goal was to carefully observe our planet.

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