As a new joint Euro-Russian space mission blasts off on a mission to Mars, to discover whether the planet’s methane is being produced by windy alien microorganisms living just below the red crust, we take a trip through the last five brain-blowing years of space exploration.
Over the last half-decade, our understanding of the cosmos has grown in ways that have shocked even those who spend most moments of their waking life staring into space—such as Dr Maggie Aderin-Pocock, presenter of the Sky at Night.
This year isn’t yet three months old and already in 2016 we’ve heard two potentially era-defining announcements about the universe: in January we learned that our sneaky solar system has probably been hiding a secret ninth planet, and then in February came the confirmed detection of gravitational waves—ripples in the very fabric of spacetime that were first anticipated by Albert Einstein a century ago.
These waves are generated in the most extreme parts of the universe, on places such as the edges of gigantic blackholes at the beginning of time, and not only do they resonate right across the entirety of space, they also permeate that all-too-often thick-skinned barrier between science and the general public.
And so they should. Because finding them is like flinging open an entirely new window into space and time, and if that doesn’t get you excited, then the search for intelligent life probably needs to refocus (closer to home).
‘Gravity is the force that holds the universe together, but it’s actually incredibly weak and these distortions in spacetime have proved a real bugger to detect,’ says Dr Aderin-Pocock, when I ask her why everyone is getting quite so excited by this news. ‘We’ve had lots of false detections and disappointments, but up until now they’ve merely been a theoretical concept. You need a colossal event to create a wave big enough to record, but now that’s happened, it could lead to the development of entirely new branches of astronomy.’
The breakthrough came after a century of conjecture and 50 years of highly concentrated effort by the international science community, proving that space does not give up its secrets easily. But this is only one example of long-term projects yielding game-changing results in recent years.
Take offs & Landings
On 25 August 2012, Voyager 1—one of two unmanned robotic probes launched back in 1977—crossed the heliopause, becoming the first human-made spacecraft to go beyond our own solar system and enter interstellar space. It has now travelled over 16 billion miles (25.6 billion kilometres) and can be expected to keep on trucking and carrying out valuable experiments until its radioisotope thermoelectric generators finally fade in around 2025.
After visiting Jupiter and Saturn (while its twin Voyager 2 dropped by Uranus and Neptune), Voyager 1 spurned Pluto to visit Saturn’s massive moon Titan. However, the New Horizons space probe flew past Pluto in October 2015, taking a series of photos revealing that the dwarf planet has blue skies and ice patches.
A month earlier, the existence of flowing water on Mars was revealed by Nasa’s Mars Reconnaissance Orbiter spacecraft, creating great excitement and renewing speculation that Martian life is—or at some stage has been—possible.
Even more impressively, in the last few years we’ve seen scientists park a probe on one of the most intriguing of heavenly bodies: a comet. Often dramatically visible with the naked eye, the appearance of a comet in the night sky has historically been greeted with fright and foreboding, with the objects branded as harbingers of doom, but these objects are a source of fascination for modern astrophysicists.
‘Comets are particularly interesting because they’re made from the debris left behind from the foundation of our solar system,’ says Dr Aderin-Pocock.
For decades scientists have dreamed about getting an up-close-and-personal look at a comet, to sift through physical data and discern clues to what happened during the very early days of our Solar System, possibly discovering the origin of water on Earth and, maybe, even getting a hint of how life itself first began on our planet.
Unlike the planets, which all travel around the Sun in the same direction (prograde), comets can have both prograde and retrograde orbits. They eject up to 30 tons of material per second at the perihelion of their orbit (closest point to the sun), spewing out a great cosmic cocktail of carbon dioxide, water, ammonia and dust particles.
Their tails can be enormous, sometimes stretching cross a full astronomical unit (AU; with 1 AU being the distance between Earth and the Sun). But a comet’s nucleus is often no larger than an average town, perhaps 10km across. All of which makes landing on one incredibly tricky.
But that’s exactly what happened on 12 November 2014, when, after travelling six billion kilometres during a decade-long journey, the Rosetta spacecraft sent its fridge-sized Philae lander down to Comet 67P/Churyumov-Gerasimenko.
Not everything went completely to plan. The lander probe bounced when it hit the comet’s surface and landed in a spot where it couldn’t get sufficient sunlight to recharge its batteries, so after around 60 hours of conducting experiments and sending transmissions back to Earth, it snoozed off into ‘standby mode’. Seven months later, however, when the comet’s orbit took it closer to the sun, Philae woke up and made contact again. Contact lasted intermittently until 9 July, and in February 2016 the team conceded it had probably drifted off into a permanent slumber.
Results released thus far have revealed a number of things, including the fact that the ratio of heavy water to normal water on the comet is more than three times that found on Earth, which means our oceans are unlikely to have originated from comets like 67P. In April 2015, scientists revealed that the comet’s nucleus has no magnetic field, but in October they reported that they had detected high levels of molecular oxygen around 67P.
Meanwhile, the Rosetta orbiter has continued circling 67P, escorting the comet around the Sun, performing riskier investigations and making scientific observations of its own. In September 2016, the mission will come to a dramatic end when scientists slow crash-land the orbiter onto the comet. Rosetta has more powerful and varied sensors and instruments than Philae, and will descend slower, which should allow it to gather more data and better images.
Exoplanets, Twin Earths & Aliens
Beyond all this, we are also now aware of the existence of at least 2086 exoplanets spinning around in 1330 different and distant star systems. The vast majority of these are within the Milky Way, but a handful of extragalactic bodies have been spied too, with varying degrees of confirmed accuracy.
Before 1988 none of these far-away worlds had been detected—and it took until 1992 before one (actually, three: Draugr, Poltergeist and Phobetor) could be 100 per cent confirmed. Since the launch of the Kepler space observatory in 2009, however, thousands of exoplanets have been spotted, with over 900 bagged in 2014 alone.
Typically, Dr Aderin-Pocock explains, exoplanets are discovered and measured via the transit method, which is possible when the planet passes in front of the star it’s orbiting. By analysing the slight dip in the brightness being emitted by that star when this happens, and studying the light curve, it’s possible to work out how large the planet is and how big its orbit is likely to be. Planets also cause their host star to wobble slightly, and by recording this scientists can figure out their mass.
Easily the most famous exoplanet to date was introduced on 23 July 2015, when NASA announced the discovery of Kepler-452b, AKA Earth 2, so-called because it’s believed to be the most similar planet to our own yet located. Inevitably, this created feverishly excited headlines, proclaiming the imminent discovery of alien life, but as Dr Aderin-Pocock explains, things aren’t quite that simple.
‘I’m a little wary when I hear announcements about Earth-like planets and the potential of them harbouring life,’ she says. ‘Such planets keep on being discovered, usually in the Goldilocks Zone of one star or another, but there’s more to life than liquid.’
‘We recently examined the Drake Equation on the Sky at Night. This is a formula used to predict the probability of encountering life elsewhere in the universe. It uses lots of parameters, including the average lifespan of civilisations—because you’ve got to remember they typically die out after a few thousand years, and that affects your chance of overlapping.
‘After inputting all the data, we ended up with a likelihood of five civilisations existing concurrently to ours in the entire universe. There are, perhaps, 200 billion stars in our galaxy, and each of them might have several planets orbiting around them, so it’s not so much a question of whether there’s intelligent life out there—it’s more about the extreme difficulty of finding it.’
However, there is a way that such a search could be narrowed down to some prime suspect planets. As the technology used to build telescopes improves, astrophysicists are increasing able to not only figure out the location and dimensions of an exoplanet, but also analyse the spectra of light around it to work out what gases exist within its atmosphere, and even assess whether it could possibly support life. Potentially, says Dr Aderin-Pocock, we could see whether a civilisation has left polluting prints on a planet, by checking for the existence of gases such CFCs, which cannot be produced by nature.
Come in Number 9
But it was the probable discovery of a ninth planet knocking around in our very own front garden that really surprised Dr Aderin-Pocock, and many of her fellow space scientists.
As we’ve seen, Earthlings’ understanding of the complexity of our own solar system is improving all the time, but since the 2006 relegation of Pluto from a proper premier-league planet player to the dwarf ranks, where it keeps company with the likes of Haumea, Makemake and other such characters in the Kuiper Belt, scientists did at least think they had the planetary seating plan sorted out.
On 20 January 2016, however, it began to look like all those diagrams and models of our sun and neighbourhood planets might have to be revised. Again.
This is the date that Konstantin Batygin and Michael E Brown, scientists at the California Institute of Technology (Caltech), disclosed that they had found evidence of a massive planet orbiting the sun at the extreme edge of our solar system. The planet had been sensed, rather than seen, with its presence predicted by the eccentric behaviour of distant Kuiper Belt Objects (KBOs), which suggested they’d had a run in with a large celestial body.
Using mathematical modelling and computer simulations, they calculated that this mysterious monster must be two to four times the size of Earth, with a mass 10 times as large as our planet. With an extremely elliptical orbit, it probably takes anywhere between 10,000 and 20,000 years to orbit the sun.
Other space scientists subsequently chipped in with rival theories about the planet’s orbit and likely influence on KBOs, notably the University of Arizona who recently published a paper called ‘Coralling a distant planet with extreme resonant Kuiper belt objects’, but there is a general consensus that it exists.
‘Planet 9 shook me up somewhat,’ admits Dr Aderin-Pocock. ‘We all thought we had our own solar system done and dusted, but here’s this giant planet. So now the search has started.’
And that actually presents far more of a challenge than finding much further-flung worlds, because the transit method can’t be used to spot a planet in our own solar system, at least not if its further away from the sun than us. And Planet 9 is an awful long way out—between 600 to 1200 AU, depending on where it is during its massive orbit.
Seeing the Light
This is where the astronomical advancements in the tools and technology our species uses to gaze into space will make all the difference. If the last five years has seen a flurry of game-changing revelations, the next decade promises to deliver even more, with the construction of increasingly massive telescopes.
In terms of travelling into space, there are certain restrictions it’s hard to see around. ‘Voyager travels at 10.5 miles [17km] per second, but even at that speed it took 35 years to reach the outskirts of our solar system,’ points out Dr Aderin-Pocock. ‘If it was able to keep going, it would be another 76,000 years before it arrived at our nearest neighbouring star, Proxima Centauri.
‘Although recent advancements in ion drive thrusters and solar sail technology may allow us to go further and faster into space, unless we learn to master wormholes or something, I think we’re physically limited to exploring our own solar system.’
However, humans are peering ever deeper into the universe, and by doing so effectively looking back in time towards the very moment the universe was created, with increasing powerful instruments.
The Hubble space telescope is still going strong, and may continue to work for another couple of decades, but its successor the James Webb Space Telescope (JWST) is scheduled to hit the heavens in October 2018. The JWST boasts a mirror more than twice as large as Hubble’s, and offers space spies unprecedented resolution and sensitivity, ranging from long-wavelength (orange-red) visible light through to to mid-infrared.
Back on terra firma, the fabulously named VLT (Very Large Telescope), aided by Laser Guide Star (LGS) technology, which literally takes the twinkle out of the stars so they can be stared at, has been making extraordinary discoveries for years. However, it will soon be superseded by three ELTs (Extremely Large Telescopes) currently under construction, and there’s even talk of an OWL (Overwhelmingly Large Telescope), with a single aperture of 100 metres in diameter.
The ways in which we peer into space have changed radically over the last few years too. Data about the core properties of the universe collected during NASA’s Wilkinson Microwave Anisotropy Probe (WMAP) resulted in a new Standard Model of Cosmology, and in 2013 the Euro-led team behind the Planck Cosmology Probe produced an up-dated all-sky map of the cosmic microwave background (CMD), showing thermal radiation left over from the Big Bang. These results suggest the universe has existed for 13.798 billion years (making it older than previously thought) and reveal that it’s comprised of 4.82% ordinary matter, 25% dark matter and 69% dark energy.
Twenty countries are currently invested in the construction of the Square Kilometre Array (SKA) in Australia and South Africa. This massive multi-radio telescope, which promises to be 50 times more sensitive than any other radio instrument, will use an array of internationally spaced out small disks operating over a wide range of frequencies to create a total collecting area of around a square kilometre, enabling scientists to survey the sky ten thousand times faster than before.
‘2015 was the International Year of Light and Light-based Technologies—although I’m not sure that many people realised,’ laughs Dr Aderin-Pocock. ‘But, the point is, we’re seeing the light and observing space in so many new ways now. People are looking a microwaves and radiowaves, and discovering amazing things. The SKA will vastly improve our understanding of the universe.
‘Ten years ago people would have laughed at the suggestion of Planet 9, but now, with the speed at which we’re discovering exoplanets, we could be looking at billions of worlds soon. And if there’s a big planet hiding in our own Solar System…who knows what else might be out there?’