How close are we to discovering alien life?

Recent months have heralded major discoveries of potentially habitable planets – from Kepler 186-f, an earth-sized planet in the “habitable zone” of a star 500 light years from earth to Kapteyn b – an ancient planet that could support life, and is “just” 13 light years away.

We can expect wild things when one day we can probe these planets. Dr Guillem Anglada-Escude

On Tuesday an international team of astronomers announced the discovery of Kapteyn b and the larger Kapteyn c, a planet which is said to be too cold to support life.

Kapteyn b, however, is an ancient planet orbiting Kapteyn’s Star within the “habitable zone” – where conditions are right for water to exist in the atmosphere – the key to potential life.

Time to evolve

Dr Guillem Anglada-Escude from the School of Physics and Astronomy at Queen Mary University of London, who led the team of astronomers, told Channel 4 News that the discovery is interesting because the planet is “nearby” and “very old”.

The Kapteyn planets and star are estimated to be around 11.5 billion years old, 2.5 times older than Earth and “only” two billion years younger than the universe itself.

Above: Artistic representation of the Kapteyn b with Omega Centauri in the background. Credit: PHL at UPR Arecibo, Aladin Sky Atlas.

“It shows habitable planets have been around for a long time,” Dr Anglada-Escude said. “This means the places where life can emerge can have been around for much longer.”

“If life can emerge in four billion years on earth than it can emerge in 12 billion years in places like this.”

The astrophysicist said that on planets such as Kapteyn b life has had “time to evolve” even if it is more difficult for evolution to take place on such planets.

“We can expect wild things when one day we can probe these planets,” he said.

Probing atmospheres

Greater precision in the way the universe is explored has led to an explosion in planetary discoveries – from Doppler spectroscopy, which discovers nearer planets, to the Kepler telescope which searches for distant planets.

We are on the brink of being able to answer the question. Dr Guillem Anglada-Escude

Astrophysicists are searching for all kinds of heavenly bodies – but planets in the habitable zone, also known as the Goldilocks zone (not too hot or too cold to support life) provide tantalising possibilities of one day discovering alien lifeforms.

Other habitable worlds

In April Nasa announced the discovery of Kepler 186-f, the first "earth-size planet in the habitable zone". The planet, 500 light years from earth, is 10 per cent larger than earth and likely to be rocky.

Tau Ceti e is an unconfirmed planet that may be orbiting the star Tau Ceti, which is approximately 12 light years from the sun. If Tau Ceti e possesses an earth-like atmosphere, the surface temperature would be around 70 degrees Celsius, meaning the only earth life that could exist on the planet would be thermophile organisms.

Kepler 62-e is around 60 per cent larger than earth and it is thought that the planet could be terrestrial, or entirely covered with water or ice.

At around seven times large than earth, HD 40307 g is known as a "super-earth". It is 42 light years from the sun.

Dr Anglada-Escude said that a “ten-fold increase in precision” led to a “100-factor increase” in the number of planets being discovered.

And with more technological advances, the next generation of star-gazing equipment is likely to reveal more about habitable planets in the universe.

Channel 4 News asked Dr Anglada-Escude if we will soon discover life on other planets.

“We are on the brink of being able to answer the question,” he said. “We might not be able to find it (life) but we will have the means to really start probing atmospheres of these planets.”

There is, in other words, more than adequate cosmic real estate for extra-terrestrial life, including intelligent life. Seth Shostak, Seti

However, Dr Anglada-Escude emphasised that it would be lucky to quickly find any form of life. He said: “It could be that there is no life, it could be that there is no water. It (life) is a possible answer.”

But for anyone dreaming of extra-terrestrial adventuring à la Star Trek – visiting such planets is currently out of the question. It would take a mission “a couple of thousand years” to reach Kapteyn, unless there is a “major breakthrough in the fields of physics”.

Alien cities

The form that life could take on this and other planets is unknown, but the Kapteyn team added a creative edge to their research by commissioning a science fiction writer, Alistair Reynolds, to imagine a mission to Kapteyn b.

Mr Reynolds wrote about a world where “cities cover almost the entire surface”, enormous structures reach into space and the civilisation that inhabited the planet had stretched out – colonising its moon and Kapteyn c.

The fictional world was dead, the writer wrote, apparently destroyed by a “truly awesome catastrophe”, evidenced by “continent-sized craters”.

You can read Mr Reynolds’ short story, Sad Kapteyn, here. The real story of Kapteyn’s Star is dramatic in itself – originally part of a dwarf galaxy it was absorbed and disrupted by the Milky Way.

Cosmic real estate

Dr Anglada-Escude said that the ability to answer the question of life on other worlds will be available in the next five years.

In 2018 Nasa’s James Webb Space Telescope is due to be launched – a space observatory which will “study every phase in the history of our universe, ranging from the first luminous glows after the Big Bang, to the formation of solar systems capable of supporting life on planets like Earth”.

The imaginatively named European Extremely Large Telescope, due in five or six years, will be able to characterise the atmospheres of planets in the search for life.

Above: Artist’s impression of Kepler-186f. Image credit: NASA Ames/SETI Institute/JPL-Caltech

And Dr Anglada-Escude is not alone in predicting giant leaps in the field of extra-terrestrial discovery.

At a hearing of the US House Committee on Science, Space and Technology, Seth Shostak, senior astronomer at Nasa’s Search for Extra-Terrestrial Intelligence institute (Seti), said that “it is not hyperbolic to suggest that scientists could very well discover extra-terrestrial intelligence within two decades’ time or less”.

Mr Shostak said research suggests the Milky Way is “home to 10 to 80 billion cousins of earth”.

“There is, in other words, more than adequate cosmic real estate for extra-terrestrial life, including intelligent life,” he said.