CHENNAI: The Indian Space Research Organisation placed six Singaporean satellites into a 550 km circular orbit late Wednesday evening in what was the 32nd flight of the nation’s highly successful PSLV launch vehicle.
Putting foreign satellites into orbit successfully has become a matter of course for ISRO. However, Wednesday’s mission was more about another first that the ISRO managed to pull off during the same mission. For the first time, the PSLV’s fourth stage was successfully restarted in space 50 minutes and 0.05 seconds after it cut off.
The ability to restart a rocket stage that has shut down is a critical ability for any launch vehicle if it is to be capable of putting multiple satellites into completely different orbits during the same mission. Thus far, the PSLV has been unable to boast the capability.
The PSLV-C29 mission went off without a hitch all through the launch, stage separations and separations of the six Singaporean satellites it carried into orbit. But, scientists at the control centre did not relax once the final satellite had been successfully injected. All eyes were on the fourth stage of the rocket as it silently coasted along its orbit until exactly 50 minutes and 0.05 seconds after it was shut off and ISRO pressed the button to re-start the stage.
“The restart test was successful. The engine was fired for nearly five seconds. We will be using this technology sometime next year,” said ISRO chairman A S Kiran Kumar. According to him the next three satellite launches using PSLV rocket would be navigation satellites.
After those launches, there would be multiple satellite launches and this technology would be used in them. ISRO sources said the first mission to use the technology would be the PSLV-C35 mission.
The successful testing of the ability puts ISRO in a much better position to make more efficient use of the PSLV to deliver payloads — both its own and other countries’.
No longer would satellites have to be clubbed together and released into limited orbits but the space agency would be able to steer the fourth stage into different positions to inject satellites into multiple orbits — all with a single rocket.
Before the successful test of the fourth stage, PSLV-C29 brought ISRO and Antrix Corporation’s count of foreign satellites placed into orbit to 57.
The primary satellite of the mission was the 400 kg TeLEOS-1 — the first Singaporean commercial Earth observation satellite designed and developed by ST Electronics.
The other five co-passenger satellites were the VELOX-CI, a 123 kg microsatellite for tropical environmental research, the VELOX-II, a 13 kg technology demonstrator, the Athenoxat-1, a technology demonstrator for remote sensing, the Kent Ridge-1, a 78 kg micro-satellite with two cameras and the 3.4 kg Galessia — with instrumentation to collect quantum correlation data in space.
ISRO reaches half century milestone in number of launches from Sriharikota
■ With PSLV-C29, ISRO has launched 50 rockets from SHAR. Initially called the Sriharikota Range (SHAR) and renamed Satish Dhawan Space Centre (SDSC) in 2002, the space port became operational in 1971 when an RH-125 sounding rocket was launched. The first attempted launch of an orbital satellite — Rohini1A — aboard a satellite launch vehicle, took place on 10 August, 1979.
2015 sees ISRO launch 21 satellites
■ The space agency has launched 20 satellites — three Indian and 17 foreign — from Sriharikota this year.
■ In November, ISRO also launched the GSAT-15 through the Ariane rocket of the European Space Agency taking the total number of satellite launches in 2015 to 21.