Riding on light in search of other life

Man’s curiosity to find earth-like planets or alien life-forms in the vast realms of our universe is an insatiable one. With rapid technological advancements, scientists are peering into the enormous expanse of our galaxy. Space is being explored like never before.

The last two decades saw an ever-growing list of discovery of exoplanets (earth-like planets). Several space missions and probes (like the Kepler Space Telescope) further strengthened this search with more than 5,000 planetary systems discovered so far.

Of these, 3,000 have been verified as promising candidates — they satisfy the ‘Goldilocks’ principle which refers to optimum temperature on the planet to hold liquid water, the right distance from its parent star and other astronomical criteria.

To corroborate these findings, the only factor that is posing a drawback is the lack of technology to send probes to these planets and take a closer look at them. The hurdle: enormous distances to travel. Considered astronomically, many are just a few light years away; however, in perceptible figures, they run into trillions of kilometres.

The best of our present day spacecraft like New Horizons or Juno use chemical propellants which can travel at top speeds of 50,000 to 2,00,000 km per hour. At this spped, it would take them tens of thousands of years to reach the nearest
star, which is 41 trillion kilometres away. Hence, sending such space probes is not a feasible idea. The probes need to travel at a velocity comparable to the speed of light — which is 3,00,000 km per second — to make the journey a tangible one.

Light, which is a source of energy, is capable of pushing objects. If ships can travel on sea using wind energy to propel them, can light give the required push to our space probes? Eminent physicist Stephen Hawking proposed and conceptualised this theory to be adapted to space travel. His approach received enthusiastic support from Russian venture capitalist Yuri Milner and other scientists.

In 2015, their collaboration gave birth to Breakthrough Initiatives, a 130-million dollar venture dedicated to visit, observe, detect, and listen to distant planetary systems. However, the only limitation to overcome in this theory lies in the fact that light can push only tiny objects, weighing a few grams at the most.

The present day’s miniaturisation technology is encouraging here. The design and development of miniscule probes which will be beamed into outer space at high velocities is the main agenda of Breakthrough Starshot.

The project will develop tiny, unmanned nano-crafts called StarChips, the size of postage stamps and weighing just a few grams, which will house all the necessary equipment along with a ‘light sail’. An array of StarChips will be positioned in space by a satellite. From there, they will be beamed into outer space, gaining momentum to travel enormous distances at expected travel speeds of 20% the speed of light. The required light beam comes from a 100-gigawatt laser positioned at a high altitude facility on earth.

Breakthrough Starshot’s target is the exoplanet discovered in 2016 - Centauri b - orbiting Proxima Centauri, Sun’s closest neighbour 4.5 light years away. They claim these probes will reach Centauri b in a mere 20 years, and the project is touted to be a reality in the coming two decades.

Validating their claim in July this year, Breakthrough Starshot launched their first fully functional prototype probes — ‘Sprites’ — into Low Earth Orbit. Piggybacking on the Venta satellites, these 3.5cm by 3.5cm nano-crafts designed on a single circuit board weigh four grams and contain all the required equipment: solar panels, computers, radios and sensors along with the light sail. Currently, they are undergoing rigorous tests for space sustainability.

During his speech, Hawking said: “The limit that confronts us now is the great void between us and the stars, but now we can transcend it.” With such path-breaking ventures in the horizon, the decades to come will witness crucial discoveries. Detection of life-supporting environments by these StarChips will be undeniable evidence in support of extra-terrestrial life. Humanity awaits with bated breath, for the truth lies out there!

Many of us grew up watching sci-fi series and movies with wide-eyed fascination. It is thrilling to realise that yesterday’s imagination is manifesting today as a reality. As Hawking speculates, “Humans may one day explore far off planets travelling on a beam of light.”

Man is, indeed, on space exploration like never before.

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