ISRO to design fourth stage rockets that stay 'alive' for experiments months after launch

Rocket junk floating in Earth’s orbit may be dead to the world, but is it entirely useless? The Indian Space Research Organisation (ISRO) thinks not, and has planned to put its frugal and tech-savvy sensibilities to test with a new kind of PSLV rocket that can stay alive in orbit for several months after releasing a satellite in orbit. ISRO’s first demonstration of this new technology will be during the PSLV C44 launch mission in January 2019. So far, the agency’s satellite launches on the PSLV have ended in the satellite being released into space, and the PSLV’s fourth and final stage —  the PS4  — lost as space debris. It lingers in the same low-Earth orbit as the satellite it releases, being entirely useless to anyone and anything. But after successfully building and firing up 43 **PSLV fourth stages** to orbit, ISRO thinks its time for an ambitious upgrade towards sustainability. [caption id=“attachment_5721401” align=“alignnone” width=“1280”] IRNSS-1 spacecraft (centre) integrated with PSLV-C31 fourth stage (base) with two halves of the heat shield in view, on either side. Image courtesy: ISRO[/caption] “We are working on a new technology where we will give life to this ‘dead’ last stage of PSLV, also called the PS4 stage, for six months after launch,” K Sivan, chairman of ISRO  told the Times of India. “This rocket will double up as a satellite. It will be a cost-effective way to perform experiments in space as we don’t have to launch separate rockets for this purpose,” Sivan added. This will make India the first country to work on a technology of this kind, which will be put to its first test in ISRO’s upcoming PSLV C44 launch mission, which will send an Indian microsatellite to low-Earth orbit. The fourth stage of the PSLV rocket in the mission will carry a small Indian microsatellite as the primary payload in January. The satellite,  rumoured to be an old satellite project called EMIsat, is similar to ISRO’s last earth observation satellite launch to orbit, **HySIS (Hyperspectral Imaging Satellite)** . [caption id=“attachment_5721441” align=“alignnone” width=“1280”] Parts of ISRO’s workhorse, the PSLV. Image courtesy: ISRO[/caption] The function of the repurposed fourth stage, Sivan said, is for students and space scientists to decide. The last stage will remain “alive” for experiments and testing of new space technologies for free, Sivan told ToI. ISRO will soon open its gates to proposals from students, scientists and companies that want to send their space experiments on upcoming PSLV (and future GSLV) rockets in an official announcement. With SpaceX’s reusable rockets being the sole exception, space agencies around the world have only used rockets and their stages as a one-way ticket to send up satellites. SpaceX’s Falcon 9, too, only has reusable first stages. ISRO’s repurposed fourth stage rocket will be the first project to experiment with the fourth and final stage in its launch vehicles. The agency also intends to extend this advantage to GSLV rockets in future launches.