Shuttle Imaging Radar B (SIR-B) was the second major step in the evolutionary NASA radar remote sensing research program. The radar imagery collected at the fixed look angle SEASAT and SIR-A experiments demonstrated the relationship between image intensity and the incidence angle of the radar at the surface. This led to the design of SIR-B, the first spaceborne SAR with a mechanically tiltable antenna. This allowed the acquisition of multi-incidence angle imagery.
SIR-B was launched on October 5, 1984 aboard the Space Shuttle Challenger on flight 41-G into a nominally circular orbit. The average altitude for the first 20 orbits was 360 km; for the next 29 orbits was 257 km; and for the duration of the mission 224 km. At the 224 km altitude, the orbit was allowed to drift slightly westward with an approximate 1- day repeat cycle. This enabled SIR-B to image a given site at several different incidence angles on subsequent days over the course of the mission.
An international team of scientists participated in the mission, conducting scientific investigations in geology, renewable resources, oceanography, and calibration techniques.
| Shuttle Orbital Altitudes | 360, 257, 224 km |
| Shuttle Orbital Inclination | 57 degrees |
| Mission Length | 8.3 days |
| Radar Frequency | 1.275 GHz (L-band) |
| Radar Wavelength | 23.5 cm |
| System Bandwidth | 12 MHz |
| Range Resolution | 58 to 16 m |
| Azimuth Resolution | 20 to 30 m (4-look) |
| Swath Width | 20 to 40 km |
| Antenna Dimensions | 10.7 m x 2.16 m |
| Antenna Look Angle | 15 to 65 degrees from vertical |
| Polarization | HH |
| Transmitted Pulse Length | 30.4 microseconds |
| Minimum peak power | 1.12 kW |
| Data recorder bit rate (on the ground) | 30.4 Mbits/s |
JPL Public Information Office - The SIR-B Mission
SIR-B observations of dominant ocean waves near hurricane Josephine
A comparison of SIR-B directional ocean wave spectra with aircraft scanning radar spectra
Limited numbers of the SIR-B Experiment Report from the USGS EROS Data Center
Seven hours of SIR-B SAR data were collected and all of it was processed to precision data. All of the data are archived at JPL. The data products available are:
| Product | Format | Media |
| digital | byte | 9 track CCT; 6250 bpi |
| frame | 8x10 black and white print | |
| positive transparency | ||
| duplicate negative |
Imaging Radar Home Page