Stretched Rohini Satellite Series
Indian satellite series for astrophysics and atmospheric experiments.
The Stretched Rohini Satellite Series, abbreviated as SROSS, was built by the Indian Space Research Organisation. These spacecraft succeeded the earlier Rohini satellites. Their tasks included astrophysics, Earth remote sensing, and monitoring the upper atmosphere. They also carried out new, application-focused missions. The SROSS satellites served as the payloads for test flights of the Augmented Satellite Launch Vehicle.
The first two satellites in the series, SROSS-A and SROSS-B, failed to reach orbit because their launch vehicles malfunctioned. SROSS-A carried two retro-reflectors used for laser tracking. SROSS-B had two instruments: a Monocular Electro Optical Stereo Scanner from West Germany and an Indian Gamma-ray Burst Experiment covering 20 to 3000 keV.
The third satellite, SROSS-C, reached a lower orbit than planned on 20 May 1992. Its GRB experiment monitored gamma-ray bursts between 20 and 3000 keV. Both SROSS-C and SROSS-C2 carried a GRB experiment and a Retarded Potential Analyzer. The GRB on SROSS-C operated from 25 May 1992 until the satellite reentered on 14 July 1992. It used a main and a redundant CsI(Na) scintillator, with diameters of 76 mm and 37 mm respectively, each 12.5 mm thick. A burst mode was triggered when the count rate in the 100–1024 keV range exceeded a set limit over 256 or 1024 milliseconds. In this mode, 65 seconds of temporal data and 2 seconds of spectral data from before the trigger were stored, along with 16 seconds of spectral data and 204 seconds of temporal data after the trigger. Low-resolution data came from two energy channels (20–100 keV and 100–1024 keV) covering 65 seconds before to 204 seconds after the trigger in 256-millisecond intervals. Rates from 20 to 1024 keV were also recorded at 2-millisecond resolution for one second before and one second after the trigger, and at 16-millisecond resolution for one second before to eight seconds after. Energy spectra used a 124-channel pulse height analyzer, with four pre-trigger and 32 post-trigger spectra recorded per burst at 512-millisecond integration. The RPA measured electron temperature, density, and characteristics in the ionosphere. The GRB experiment's computer used an RCA CDP1802 microprocessor.
SROSS-C2 launched on 4 May 1994. Its GRB payload was an improved version of the one on SROSS-C. Improvements included more onboard memory and better measureme
- field
- Astrophysics, Earth Remote Sensing, Upper Atmospheric Monitoring
- nationality
- Indian
- known_for
- Gamma-ray burst experiments and ionospheric studies
- first_launch_attempt
- SROSS A and SROSS B (both failed due to launch vehicle failure)
- successful_launches
- SROSS C (1992) and SROSS C2 (1994)
Lore & Background
The first two satellites in the series, SROSS A and SROSS B, did not make it into orbit due to launch vehicle failure. SROSS-A carried two retro-reflectors for laser tracking. SROSS-B carried two instruments: a West German Monocular Electro Optical Stereo Scanner (MEOSS) and ISRO's 20–3000 keV Gamma-ray Burst Experiment (GRB).
The third satellite, SROSS C (also known as SROSS 3), attained a lower-than-planned orbit on 20 May 1992. It carried a gamma-ray burst experiment and a Retarded Potential Analyzer (RPA) experiment. The GRB experiment operated from 25 May 1992 until reentry on 14 July 1992, using a main and redundant CsI(Na) scintillator. The RPA measured temperature, density and characteristics of electrons in the Earth's ionosphere. The GRB experiment computer system used the RCA CDP1802 microprocessor.
SROSS-C2 was launched on 4 May 1994. Its gamma-ray burst experiments were an improved version of the payload on SROSS-C, with enhancements to on-board memory and better measurement of background spectra after a burst event. These improvements led to the discovery of twelve candidate events detected up to 15 February 1995, out of a total of 993 triggers. The SROSS-C2 spacecraft is one of the satellites included in the Interplanetary Network. It also used an RCA CDP1802 microprocessor for the GRB experiment.
Reader's Guide
The Stretched Rohini Satellite Series represents an early phase of Indian space science, providing platforms for astrophysics, Earth remote sensing, and upper atmospheric monitoring. Despite the failure of the first two satellites, SROSS C and C2 successfully conducted gamma-ray burst experiments and ionospheric measurements. The GRB payloads on these satellites contributed to the study of celestial gamma-ray bursts in the 20–3000 keV range, with SROSS-C2's improved design enabling the detection of twelve candidate events. The inclusion of SROSS-C2 in the Interplanetary Network highlights its role in multi-spacecraft burst localization. The series also demonstrated the use of the Augmented Satellite Launch Vehicle for developmental flights, advancing India's launch capabilities. The Retarded Potential Analyzer experiments provided data on Earth's ionospheric electron temperature and density. Overall, the SROSS series laid groundwork for subsequent Indian satellite missions in space science and application-oriented projects.
Did You Know?
- SROSS A and SROSS B both failed to reach orbit due to launch vehicle failure.
- SROSS C's gamma-ray burst experiment operated from 25 May 1992 until reentry on 14 July 1992.
- SROSS-C2's improved GRB experiment discovered twelve candidate events out of 993 triggers up to 15 February 1995.
- Both SROSS C and SROSS C2 used the RCA CDP1802 microprocessor for their GRB experiments.
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