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Dr. Sarath Gunapala, a solid-state physicist, senior research scientist and group supervisor at NASA’s (National Aeronautics and Space Administration) Jet Propulsion Laboratory spoke to the Nation last week after he arrived in the country to receive the Sri Lanka Ranjana Award.

Any foreigner who functions in a State job in the USA automatically becomes a citizen of the USA and because of that Dr. Gunapala had to renounce his Sri Lankan citizenship. He is also not entitled to dual citizenship in the USA.

Q: You visited Sri Lanka unplanned to receive an award. Please elaborate.

This is the second highest Sri Lankan award conferred on a foreign national because I am currently not a citizen of Sri Lanka. This award is conferred on me for the service I extended to the advancement of Science in Sri Lanka and the international reputation I brought to my motherland.

Q: After discovering a planetary system similar to our planet Earth the interest of probing other planets in the universe caught the attention of many. What is the current state of this exploration of the universe?

About 20 years ago even top class astronomers were clueless about exactly where some planets existed. The assumption was that a certain number of planets existed in a galaxy which is similar to the Earth or Jupiter. I was working with a team of scientists who were probing the universe helping them develop necessary equipment.

A star is formed by a gaseous cloud and the remaining cloud particles form a ring around the star which, turn into planets due to gravity. About 20 years ago such observations were difficult. A professor named Jeff Mash in the University of California who observed the universe with high resolution telescopes noticed that some stars had a slight motion. Marsh came to the conclusion that this is a result of the gravity of the bigger planets rotating around them. This helped scientists to discover other galaxies. This theory helped to only discover giant planets and the planets that rotate at high speed around stars. But this methodology is not successful because it takes 22 years to observe a sun’s motion.

Q: What are the successful methods adopted to discover planets in the universe?

There are three reliable methods. Among them the Transit method is the most reliable and simple. We are fortunate if the axis of the planet we observe is parallel to the axis of the Earth. Axis is the plane in which the planets revolve around stars. But there is no way to deduce whether the axis of the star we observe is perpendicular to our planet. By repeatedly observing the intensity of light emitted by the star when the planet is parallel to the axis of the star we can measure the distance and temperature.

The Doppler method helps discover planets in the universe by observing the colour of the reflected rays of a planet we are observing.

Other one is the Gravity method. The light emitted by a star with planets deviate due to gravity. But this method is complicated.
The most reliable method among them is the Illumination Intensity method. The Kepler telescope is fixed with a photometer to gauge illumination intensity of planets. The programme was launched in 2009. It has observed about 5000 planets, and among them are 1000 confirmed planets and three out of them are of the size of the Earth. If a planet is very large it is easy to detect although smaller ones are difficult to observe. We have mostly found massive planets only.

Q: Why are you mostly concerned with small planets?

Large planets have intense gravity and it’s highly unlikely that life could exist in such planets. The other element essential for existence of life is water. The earth derived water from comets that fell on Earth. Life started on Earth millions of years later. This is why we are interested in probing Earth-sized planets. If a planet with water is close to a star, water will evaporate or if it is too far from the star water will freeze. That is why scientists search for planets similar to Earth’s conditions.

Q: What are the latest developments in the search for new planets?

A European telescope found a galaxy named Trapist which has a red star. Our universe consists of about 75 per cent of such stars. They are not bright and their mass is about 12 per cent of our Sun’s. These types of stars are considered conducive to life. NASA used a space telescope to observe the galaxy, a programme in which I also played a role. There is evidence of an atmosphere and water particles. This galaxy is not similar to ours. There are no huge gaseous planets that orbit close to the red star. There may be more similar planets but not as large. Nevertheless, due to this discovery we can be hopeful that we can one day encounter a planet similar to the Earth.

Pic by Teran Nanayakkara
(Translated by Ananda Elkaduwa)  

LIFE BEYOND THE STARS (2)