ISRO's launch vehicle PSLV-C57 rocket carrying India's first solar mission, 'Aditya-L1', lifts off from the Satish Dhawan Space Centre, in Sriharikota.
Credit: PTI Photo
When Aditya-L1 will reach its slated parking slot after four months of a solitary voyage across deep space, Indian Space Research Organisation will be the third agency to occupy such a strategic vantage point after the European Space Agency and NASA – the two space giants that will rely on the Indian data to supplement their studies.
Indian astrophysicists hope to conduct front-line research with data from the unique solar observatory that itself underwent a transformation from a single instrument carrying low earth orbit probe named Aditya to a full fledged Aditya-L1 observatory with seven instruments, thanks to former ISRO chairman U R Rao, who overhauled the mission after discussions with scientists from several laboratories.
Going by its original proposal mooted more than 15 years ago, the Aditya mission was to be a 110 kg payload carrying a single coronagraph in low-earth orbit.
But Rao chipped in to transform the project and encouraged the scientists to go for a much bigger Aditya-L1 mission with seven payloads at a steady vantage point to keep an eye on the Sun round the clock.
A key reason to drop the low earth orbit idea was that in such a position, there will be windows when the Sun will be eclipsed interrupting continuous observation.
Rao, who retired as ISRO chairman when the mission was first planned but remained active scientifically, suggested a bigger and complex solar mission eyeing the L1 slot.
“Rao was instrumental to go big on the solar mission. He realised that we have technologies to do bigger things and we should do them,” Durgesh Tripathi, a senior scientist at Pune-based Inter-University Centre for Astronomy and Astrophysics, who was associated with the solar mission for a decade, told DH.
At the L1 point – a stable watching position between the Sun and the Earth – there are other probes like ESA’s Solar and Heliospheric Observatory (SOHO) and NASA probes named ACE, WIND and DSCOVR (not looking at the Sun).
The SOHO had 12 instruments but most of them don’t work now and the coronagraph stopped working after two years when the spacecraft faced problems. The NASA probes are limited in their scope when compared against the Indian mission, which is to last for at least five years.
“Each instrument on-board Aditya-L1 will try to observe something unique to supplement what is already known. There are several gap areas, which the Aditya L-1 mission hopes to fulfil,” said Dipankar Banerjee, director of the Aryabhatta Research Institute for Observational Sciences, Nainital, who was among scientists who first proposed a satellite for solar observations in 2006.
For instance, the observations to be carried out by the Indian Institute of Astrophysics's Visible Emission Line Coronagraph (VELC) or IUCCA's Solar Ultraviolet Imaging Telescope (SUIT) have never been tried before by any other agencies.
“The coronagraph will look at the Sun from a close proximity and try to identify big solar storms whereas the UV telescope will take measurements that have never been tried from a space based platform and also important from climate change perspective,” said Banerjee.
The mission’s planned objectives are casting new lights on complex solar activities like the coronal mass ejections, monitor the near-Earth space environment, and help refine space weather forecasting models,
What is a Lagrange Point?
Lagrange points are positions in space where objects sent there tend to stay put. At Lagrange points, the gravitational pull of two large masses precisely equals the centripetal force required for a small object to move with them. These points in space can be used by spacecraft to reduce fuel consumption needed to remain in position.
In the Sun-Earth system, there are five such Lagrange points, named after Italian-French mathematician Joseph-Louis Lagrange.
The L1 point of the Earth-Sun system affords an uninterrupted view of the sun and is currently home to SOHO. Aditya-L1 will also be there