Down to Earth: Space lifeline for seafarers

10 July 2017

Interview with

Dr Stuart Higgins, Imperial College London

In this week’s Down to Earth, where we take a look at tech intended for space which has since found a new home down here on Earth, physicist Stuart Higgins is hearing how the Indian space programme is throwing seafarers a lifeline…

Stuart - What happens when the science and technology of space comes down to Earth? Welcome to Down to Earth from the Naked Scientists, the mini-series that explores how space tech is used here on Earth. I'm Dr. Stuart Higgins. In this episode, we’re looking at how India’s space programme is helping to save fishermen’s lives. The Indian Space Research Organisation otherwise known as ISRO was formed in 1969. It aims to use space technology for national development as well as scientific research. As part of this mission, ISRO created the Indian National Satellite System – a series of satellites that although being in space are very much pointed back down towards Earth. They house instruments for weather monitoring as well as radio transmitters for telecommunications, TV broadcasts, and also, search and rescue operations. It’s that latter category that led to a space tech spinoff with the stress alert transmitter. It’s an emergency beacon that can be attached to fishing boats and used to contact the coast guard in case of emergencies. While similar systems were already available, the ISRO system took advantage of the Indian National Satellite System to provide continuous coverage for the Indian Ocean. This is because the satellites are placed in a geostationary orbit. (Music) The speed with which a satellite orbits the Earth depends upon its height above the surface. Objects in low earth orbits with few hundred kilometres travel faster than those higher up. This means they orbit the Earth multiple times per day. In a case of an emergency beacon, it’s critical for the distress signal to get through at any time of day, not just when a satellite happens to be orbiting overhead. One way to achieve this is to place the satellite into geostationary orbit which is about 36,000 kilometres above the Earth’s surface. At this orbit, the relative motion of the satellite matches the rotation of the Earth. So the satellite effectively sits by the same point on the equator without changing position. ISRO’s distress alert transmitter uses a combination of the Indian National Satellite System and the Global Positioning System, GPS. So in the event of an emergency on-board a boat, the distress alert transmitter is activated by pressing a button corresponding to the type of emergency. Initially, a GPS receiver determines the boat’s location. This plus the type of emergency is transmitted by a radio up to the Indian National Satellite System. A satellite relays the signal back down to a base station on the mainland, alerting the coast guard. Although simple to use, the distress alert transmitter relies upon some serious space technology to help save lives.

That was Down to Earth from the Naked Scientists and join me again soon to learn about more space technology that’s changing lives back on earth.


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