The GRAPES-3 experiment at TIFR’s Cosmic Ray Laboratory in Ootacamund is getting upgraded. The telescope made news last year when it detected the effect of a solar storm that hit the earth in June 2015. The upgrade will play a major role in getting precise information about the propagation of storms in ‘the last million miles’ (from the L-1 point) of their journey from the Sun to the earth.
The upgraded detector will have an increased coverage of the sky and improved capacity to determine the direction of incident cosmic rays. The latter property, of being able to discern the direction of detected particles, makes it unique among cosmic ray detectors in the world; it can also to measure the intensity of the particles. Since the enhanced facility can cover a wider field of view (from present 37% to 57%), the chances of spotting solar storms will be higher.
The sun is at a distance of 150 million kilometres from the earth, and satellites have been placed at a distance of nearly 1.5 million kilometres, at the so-called L1 point, where they orbit the Sun along with the Earth. Since charged particles from a solar storm will first impact the satellites before hitting the earth, they act as an early warning system. Depending on the speed of the storm, it will take about 20-40 minutes to reach the earth from the L1 point.
However, the GRAPES-3 may differ from the satellite estimates of the travel time. This is what Sunil Gupta, Head of the GRAPES-3 experiment, terms traversing the ‘last million miles’. He says: “GRAPES-3 has an important role in understanding the propagation of storms from the L1 point to its impact on the Earth. We have seen indications that the actual time taken may not be what the satellites predict.”