Kepler: Not All That Glitters is Gold

The following is a duplicate of my Space blog found at London Student Science:

Kepler's field of view just above the plane of the Milky Way

In 2009, a mission was launched that according to NASA could discover thousands of planets around other stars and revolutionise our place in the universe. That spacecraft was Kepler, and for nearly 4 years it has stared constantly at the same tiny patch of the Milky Way looking for the characteristic dips of light as exoplanets wander across their parent stars. But now, with a mechanical error threatening the entire mission, questions are being asked if the $600million mission really was such a revelation.

9857. That’s the number of stars Kepler has seen glitter with the tell-tale sign of nearly 16000 exoplanets. It is remarkable then that 99.2% of these remain unconfirmed, with only 120 being recognised by the astronomical community as planets. It’s not just because NASA is swamped with data: to be confirmed every planet discovery must be analysed by a different method. This usually involves ‘weighing’ the planet using the motion of the star to determine how strong the gravitational attraction of the planet is. More intriguingly, follow-up observations can even reveal the atmospheres of such exoplanets, paving the way for the search for alien life.

Here comes the downside; finding a planet’s mass or studying its atmosphere is only possible when it circles a bright star. Kepler, on the other hand, has been searching for small planets around dim and distant stars. It has, effectively, spent 4 years and hundreds of millions of dollars looking for planets that will forever remain unconfirmed and uncharacterised. This is especially pertinent when compared with the much cheaper ground-based surveys that have found more confirmed planets around bright stars.

The telescope at OHP hunting for  Kepler planets

While it is certainly a disappointment that these planets may never be seen again, can’t NASA just assume their haul of ‘planetary candidates’ are all real? According to a recent study, the answer is no. Astronomers at the Observatoire de Haute Provence went hunting for Kepler’s planets. They found that more than a third of these so-called planets were anomalies produced by a second star. Without knowing how many planets are phantoms, even the recent predictions of a 100 billion planets in the galaxy may be stabs in the dark.

But, despite a few negatives and some overly optimistic goals of the NASA team, Kepler has been successful. The majority of its planets will turn out to be real, including a handful of Earth-like worlds that could support life (even if we never get a closer look). And if the ‘bias’ in Kepler’s results can be figured out, it could provide us with fascinating statistics showing just how common solar systems like our own might be.

That makes it an even greater shame that the spacecraft is wounded. To keep Kepler staring at the same patch of sky, it makes use of 3 ‘reaction wheels’. But after the failure of one of these stabilisers last July, the discovery of wear and tear on a second wheel in January 2013 could prove fatal. For those working on Kepler, the next few weeks will be anxious as they try to fix the problem from the ground, and, despite its shortcoming, I hope they manage it.

Finding Life in Other Solar Systems

After a busy day at work, you emerge from the office into a fading March evening of 2029. Taking the usual route home, you check your phone for the first time in hours and discover 12 new messages. The first one simply says “Have you heard?!”. Your heart rate quickens. What could this exciting news be? Fumbling for the next message you quickly skim the text… In a state of shock, the phone drops from your hand. This is the moment you, like the rest of humanity, learn of the most important scientific discovery in centuries: that life exists elsewhere in the universe.

Although this vision of the future may seem speculative, the technology to detect life on planets around other stars already exists. All that is lacking is the enthusiasm of the general public and the financial backing of the world’s governments.

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The 20^th century was a truly optimistic time for those looking for life elsewhere in the universe. The early part of the century saw huge public intrigue over possible canals on Mars. However, by the time the Viking probes arrived in the 1960s, Mars was known to be a cold and desolate place. More recent rovers have confirmed that if Mars was ever habitable, it has not been so for billions of years. Missions to Jupiter and Saturn have also captivated public attention, with moons such as Europa and Titan being hyped to as possible havens for life. While the presence or lack of alien life in the solar system has not been settled, no environment has been found as comfortable for life as Earth’s surface.

However, in 1995 astronomers discovered the first solar system outside of our own. While this first ‘extra-solar’ planet was far from supportive to life, it marked the beginning of a new age of discovery for science. To date more than 750 exoplanets have been confirmed, and NASA spacecraft Kepler has found more than 2321 candidates including numerous Earth-sized planets. The Gaia mission, launching next year, could also potentially discover tens of thousands more. This revolution is space sciences mean there are now thousands more places to look for life in the universe, and missions have already been proposed to do just that.

The Darwin mission, with 6 space telescopes.

Since the early 00s both NASA in America and ESA in Europe hatched similar plans to fly an array of planet-hunting space telescopes high above the Earth. NASA’s Terrestrial Planet Finder, or TPF-I, and ESA’s Darwin mission comprised of between three and six 1.5m telescopes collecting infra-red light from a target star system. The telescopes would fly in a precise formation, allowing the light detected from each dish to be digitally combined. Not only does this processing give an effective telescope diameter of 100m, it also enables the light from the parent star in this system to be removed. This is called interferometry and is frequently used on ground-based telescopes including the Very Large Telescope array in Chile. Unlike in Chile, however, the distorting effects of Earth’s atmosphere are removed, and this array of space telescopes would be able to directly observe and characterise Earth-like planets.

The spectra of  Mars, Earth and Venus.
Only Earth, with H2O, CO2 and O3 is habitable

By measuring the light coming from such a planet across a variety of wavelengths, the TPF-I or Darwin missions could take spectra of any Earth-like planet discovered. These infra-red spectra could probe their atmosphere, and can tell if such a planet is inhabited. Life as we know it produces a distinctively imbalanced atmosphere. On Earth large amounts of oxygen coexist with methane, ozone, carbon dioxide and water; a mix that without life’s unique processes could not exist for long. “I would be 99% sure that life was present if I saw this combination of planetary characteristics” says Professor James Kasting, writer of the book How to Find a Habitable Planet.

These missions were capable of putting to rest one of the biggest questions ever asked by a conscious mind: ‘Are we alone in the universe?’ Geoffrey Marcy, exoplanet pioneer, said “I think TPF is our Human Genome Project”. What happened to TPF and Darwin, I hear you ask. In 2007 Darwin were indefinitely shelved, and  in 2011 Terrestrial Planet Finder was cancelled completely. In total both projects wasted more than 10 years planning and many millions of dollars of funding with no end result.

One of the main factors blocking the development of such an Earth-finding mission is cost. Such a project could plausibly run to tens of billions of pounds. While this figure dwarves the biggest science experiment ever made, the Large Hadron Collider at CERN (a mere $9bn), it pales in comparison to other projects, such as war in Afghanistan ($120bn a year) and global tax evasion ($3100bn!). Just like the LHC, this cost could be spread between European states and the US, and even new space-faring nations such as India and China. For a project that might answer fundamental questions about our universe and captivate people across the planet, a few billion pounds really doesn’t seem that much to ask.

James Kasting believes that, without the interference of politics, such a concept could be designed, built and flown into space within 15 years. And the only way to get such plans onto the table is to tell the politicians and policy-makers of the world that this matters to us. This groundswell of public interest in exoplanets & astrobiology could mean that on one evening in 2029 you discover that our Earthly biology has done the unthinkable; discovered life on another world.

The Sagan Series

I am unfortunate to have not been born when Carl Sagan put his voice to the Cosmos series in 1980. I watched the first series for the first time only recently and, despite it being over thirty years old, it is still a breathtaking voyage through human history, exploration and ingenuity. And even today, scientists can be heard still singing with praise for what was one of the most-watched science shows on the globe. When the great american astronomer passed away in 1996, the world lost one of its most important thinkers. 

So I was astounded to watch a newly made video with Sagan's characteristically calm voice over the top. NASA [EDIT: actually its this guy], using snippets of previously-recorded audio material and hundreds of high-definition videos, have put together a series of short films based on Carl Sagan's wonderful thoughts. They are simply awe-inspiring. Throughout all eight parts, the hairs on my skin were lifted in sheer joy. Just as Cosmos did before, this series has the power to inspire another generation of school-children into science.

But don't take my word for it. Just watch...