The Transiting Exoplanet Survey Satellite will launch later this month, but what has taken us so long in the hunt for alien life forms?
Are we alone in the universe? Nasa's new TESS is shooting off into orbit to find out
Are we alone in the universe? Whatever the answer, it is shocking in its implications. Now scientists are hoping to find out if it lies on our cosmic doorstep.
Later this month, Nasa will launch TESS – the Transiting Exoplanet Survey Satellite – which will orbit high above the Earth searching for potentially habitable planets beyond the solar system.
Such searches have been done before. Nasa's own Kepler space observatory, launched in 2009, examined over 150,000 stars in a small patch of the night sky using the same technique as TESS.
Orbiting planets cut across – “transit” – the face of their parent star, producing a slight drop in brightness. By detecting these transits, the ultra-sensitive light detectors on Kepler found that around 1.5 per cent of the stars are accompanied by at least one “exo-planet”.
Astronomers now think there could be tens of billions of Earth-like planets able to sustain life strewn across our galaxy. But most are so distant there is no hope of finding out what they might harbour.
What makes TESS different is that it’s focusing on stars much closer to home.
Scientists working on the mission think they’ll be able to find dozens of Earth-like planets within just a few hundred light-years of the solar system.
Once located, these planets will then be targeted by huge telescopes now being built that will study them in detail for signs of life.
Within the scientific community, there is now palpable excitement about the progress in establishing our status in the universe.
Yet for some people, this just raises another question: what took the scientists so long? They believe the issue was settled years ago by the countless reports of UFOs.
Tin foil hats at the ready
Long regarded as a litmus test for gullibility, merely suggesting UFOs might be evidence of alien life is potential professional suicide for scientists.
But new and seemingly reputable accounts of close encounters with strange craft with extraordinary capabilities hints at a potential rethink.
In December, the New York Times reported incidents involving US military ships and aircraft, along with the existence of the Advanced Aerospace Threat Identification Program, a partly-classified effort at the US Department of Defence to understand their significance.
One such incident began in November 2004, when the USS Princeton, a Navy cruiser, tracked unknown objects that appeared on radar at altitudes of 25 kilometres – far above conventional aircraft flight paths – and then plunged down towards the sea.
Fighter pilots sent to investigate could detect nothing visually or on radar, but then noticed a whitish oval-shaped object around 15 metres long just over the surface of sea.
As they approached, the object came up towards them, and then zipped across the sea at an astonishing speed, estimated at around 4,000 km/hr.
Yet for true believers in alien visitations, the disclosure of the Pentagon’s covert programme and reports of incredible phenomena was old news.
They point out that the US Air Force is already known to have investigated more than 12,000 UFO sightings in a project that ended in 1969. Analysts found that over 95 per cent were cases of mistaken identity: cloud formations, stars, planets and the like. But that still left over 700 that could not be explained.
Nor do the incidents reported by the New York Times seem especially impressive compared to events like the so-called Belgian UFO wave that began in late 1989.
Unknown objects were sighted by thousands of eye-witnesses and corroborated by air force radar operators, and twice led to F-16 fighters being dispatched to investigate.
On the first occasion, the object vanished from ground radar was the fighters approached, but appeared again when they departed. According to the Chief of the Belgian Air Staff, the fighter pilots also detected the object on radar, but could see nothing.
In late March 1990, police reports of sightings of unusual objects in the skies over Wavre, central Belgium, again led to fighters being sent to investigate, with the same result.
While invisible to the pilots, their radar systems detected an unknown object thay they described as a “structured UFO”.
As with the USS Princeton incident, the object performed extraordinary manoeuvres, accelerating from around 280 km/hr to 1,800 km/hr in just a few seconds – far higher than a human pilot could tolerate, and without producing a sonic boom.
The Belgian authorities said they would treat the events “with the utmost seriousness”, but no explanation has ever emerged.
Sceptics rightly point out that none of this proves that UFOs have aliens at the controls. But as astronomers shorten the odds on habitable planets within our cosmic neighbourhood, the standard put-downs are starting to lose their force.
Many scientists happily accept alien life exists somewhere in the galaxy, but add that even travelling at the speed of light it would take thousands of years for them to reach us, and why should they visit in any case?
This overlooks the fact that for more than 90 years radio transmissions announcing our existence have been streaming out into space. As such, they have passed through hundreds of star systems on the way. The discovery of nearby exo-planets makes that potentially very significant.
Professor Freeman Dyson, one of the world’s most distinguished theoretical physicists, based at the Institute of Advanced Study at Princeton, New Jersey, was once asked for his definitive argument against aliens visiting the earth. His blunt response: "There isn't one – the fact is we just don't know".
This month’s launch of TESS is the most significant step towards getting an answer. It may also help scientists move on from being perfectly comfortable with the existence of aliens – as long as they keep their distance.
Robert Matthews is Visiting Professor of Science at Aston University, Birmingham, UK