It’s October 2018 and NASA scientists are monitoring the Kepler space telescope as they have been for more than nine years. The ship has been scouring our galaxy, the Milky Way, for planets that might potentially support life. But disappointment for the NASA team is just around the corner. Abruptly, Kepler’s transmission of data to Earth comes to a halt.
NASA launched the Kepler telescope in March 2009 from Florida’s Cape Canaveral Air Force Station. Its mission, which came with a $600-million price tag, was to find planets that were likely candidates to have a life-supporting environment. Engineers had believed that the spaceship likely had a three-and-a-half-year lifespan, but happily that proved to be a wildly inaccurate estimate.
Kepler’s purpose as it travelled through space was to identify what are called exoplanets. These are planets orbiting suns outside of our solar system. And for its part, Kepler was searching the skies for planets in the Milky Way that had at least the possibility of supporting life.
Kepler was hunting planets that were orbiting their stars, or suns, in a region called the habitable zone. That means a planet which is within the right distance from its sun to be able to support liquid water on its surface. Indeed, this optimum area around a sun is the region where the likelihood of life is at its highest.
So Kepler was looking for life elsewhere in our Galaxy, away from our Solar System. But what had caused the space telescope’s demise in 2018? Were there perhaps beings on other planets who realized what we Earthlings were up to? And had these sentient creatures decided that they would rather not be found by us?
We’ll come to an answer for those questions a little later, but first let’s learn more about how we humans have searched for alien life over the years. Perhaps the earliest of the alien hunters was the Serbian-American engineer Nikola Tesla. Of course, he’s the man that Elon Musk chose to name his electric cars after.
In 1896 Tesla decided that it might be possible to contact intelligent life on Mars using radio signals. Indeed, he had been experimenting with early wireless broadcasting systems and thought his equipment might be able to pick up signals from space. Three years later, he believed that he had indeed picked up signals from the Red Planet that sentient beings might have transmitted.
However, subsequent researchers were skeptical that the signals were meaningful. And of course we now know that there is certainly no life on Mars capable of radio transmissions. In fact, some scientists have wondered if Tesla had actually picked up radio waves from Guglielmo Marconi, the Italian scientist working with early radio equipment in Europe.
Indeed, Marconi was another who believed in the possibility of detecting radio signals from Mars. And many others shared his thoughts. For example, in 1924 scientists called for a National Radio Silence Day in the U.S. to create the best conditions for detecting signals from Mars. And the driving force behind this idea was the eminent astronomer David Peck Todd.
Todd recruited the U.S. Naval Observatory to help with his experiment. It launched a balloon up to an altitude of almost two miles with radio equipment attached. A code-breaker was on stand-by to decipher any messages that the Martians might send. But to general disappointment, the experiment drew a big fat blank.
Nevertheless, the possibility of alien life continued to exercise the public mind. Enthusiasm for all things extraterrestrial got an extra boost following an incident in the summer of 1947. A mysterious object crash-landed on a farm about 30 miles from the city of Roswell in New Mexico. This event generated an extraordinary reaction in the press, triggered by a statement released by Roswell Army Air Field.
Amazingly, the press release mentioned a “flying disc.” And subsequently the Roswell Daily Record splashed the story on its front page under the banner headline “RAAF Captures Flying Saucer On Ranch In Roswell Region.” A number of media outlets then quickly picked up the story. And the report launched a positive deluge of UFO sightings elsewhere, too.
So it seems that many of Earth’s inhabitants have a burning interest in the idea of intelligent life on other planets. And the space telescope at the heart of our story, the Kepler, was designed to explore the Milky Way Galaxy in a search for planets that could support life, perhaps even intelligent life.
But getting the Kepler project off the ground was far from an easy task. The man behind the scheme was the esteemed space scientist William Borucki. He was born in Chicago in 1939 and spent his childhood in Delavan, Wisconsin. Borucki joined NASA after earning a master’s in physics in 1962 from the University of Wisconsin.
Borucki worked on the Apollo program, designing heat shields. These devices stopped re-entry capsules burning up as they hurtled towards the Earth’s surface at the end of a mission. However, his focus had changed in 1983 when the scientist began to concentrate on the hunt for exoplanets, planets outside our own solar system.
Now working at the Ames Research Center, a NASA facility at the Moffett Federal Airfield in California, Bourke started research into identifying distant planets. The direction of his research involved detecting planets from the variation of the light signals from stars. The light that stars emit varies as planets pass across them – and observers can identify planets from this signal.
This method of detecting planets many light years away is called transit photometry. It depends on having equipment sensitive enough to measure light variation from far-flung stars. Borucki now concentrated his efforts on finding the best methods of accurately measuring the changes in stars caused by planets moving across them.
Meanwhile, the first confirmed discovery of exoplanets came in 1992. It was the Arecibo radio telescope on the island of Puerto Rico that made the breakthrough. Astronomers Dale Frail and Aleksander Wolszczan found two exoplanets, which were actually orbiting a pulsar, which is a burnt-out star. A third planet was found circling the pulsar, PSR 1257+12, in 1994.
It might seem counterintuitive, but research published in December 2017 highlighted the possibility that life might exist even on those exoplanets orbiting a dead star. One of the study’s authors, Alessandro Patruno, told the Space.com website, “Despite emitting deadly particles and radiation, pulsars might have [a] habitable zone.”
In the same year that those first two exoplanets were discovered, Borucki submitted his initial proposal for a dedicated NASA mission to search for more. His proposition outlined a three-year project to test the theory that the majority of stars were orbited by planets. And it hoped to ascertain whether many of those might be capable of supporting life.
But the NASA authorities didn’t buy this proposal and it was rejected. Undeterred, Borucki and his team at Ames continued research into using charged coupling devices (CCDs). Experts use the technology to detect the movement of exoplanets as they traversed their stars. Nowadays, the CCD is far from an exotic gadget – it’s what creates the images in your digital camera or cellphone.
A couple of years later, Borucki submitted a second proposal, titled FRESIP, Frequency of Earth-size Inner Planets. This comprised of a spaceship with a telescope with the power and accuracy to detect exoplanet movement, specifically planets approximating in size to our Earth. But NASA rejected the proposal. And a year after this second unsuccessful proposal, experts found another exoplanet, 51 Peg b.
This exoplanet, 50 light years distant, is especially exciting since it orbits a star similar to our sun, known by scientists as a main sequence star. Located in the Pegasus constellation, 51 Peg b is an example of a hot Jupiter planet. These are gas giant planets with very hot surfaces due to their proximity to their stars, just like Jupiter.
Still determined to get his project off the ground, Borucki now submitted a third proposal to NASA’s powers that be in 1996. This was the year after the discovery of Peg 51 b by scientists in France using the ELODIE spectrograph at the Observatoire de Haute-Provence. Indeed, that breakthrough captured widespread world press attention.
Meanwhile, it was Borucki’s third proposal in 1996 that first used the name Kepler. Johannes Kepler was a German astronomer and mathematician who lived from 1571 to 1630. He is most remembered for his laws of planetary motion. These were a key scientific breakthrough of the era which provided some of the knowledge that later informed Sir Isaac Newton’s universal gravitation theory.
Borucki then tried to convince the NASA review panel of the merits of his transit photometry project with a practical demonstration. So he and his team constructed a telescope and photometer on the ground at the Lick Observatory, not far from the Ames Laboratory in California. And the aim was to prove the capabilities of their equipment.
But the verdict, yet again, was rejection. Nothing if not persistent, Borucki submitted his proposal for a fourth time – but again, the NASA panel rejected it. But Borucki’s work clearly impressed them and they invited him to proceed further with a series of test bed experiments. These were to examine whether the Kepler telescope’s technology had sufficient accuracy to meet its goal of discovering new exoplanets.
Borucki duly built the requisite simulation equipment in his laboratory at Ames. His team now ran a series of tests, more than 160 in total. And at last NASA gave Borucki’s Kepler project the go-ahead. And by now it was 2001. From first concept in 1983 it had taken Borucki 18 years to get his Kepler project approved.
And what’s more, there was another eight years of hard work ahead before the Kepler spaceship would be launched in March 2009. And but this point, NASA had crystallized the aim of the mission. Kepler was to investigate planetary systems and to identify within them Earth-sized planets. In particular it was to search for planets orbiting in the habitable zone.
And this habitable zone was, as the NASA website puts it, “the region where liquid water could pool on the surface and support life.” Finally, the Kepler space telescope could put into practice exactly what it had been designed to do. After its launch aboard the three stages of a Delta II rocket Kepler was ready to go to work.
Then just over a month after that launch from Cape Canaveral, Kepler’s telescope started to make observations. It was focused on the two constellations of Lyra and Cygnus. Lyra’s brightest star, Vega, is 25 light years from Earth. Remember, a single light year constitutes a distance of a staggering 5.88 trillion miles.
The brightest star in Cygnus, a constellation commonly called the Northern Cross, is even more remote from our planet than Vega. That star is called Deneb, although it’s also known as Alpha Cygni. It’s no less than 2,620 light years from Earth, so Kepler was peering at objects an unimaginable distance away.
Within Kepler’s field of view were some 4.5 million stars. Out of those, the telescope was able to continuously monitor around 170,000, scrutinizing the stars to detect when an orbiting planet crossed in front of it. And success in the shape of five newly discovered planets came in January 2010. All were the hot Jupiters we heard about earlier, giant gas planets with temperatures in excess of 2,000°F.
Then just a few days later, Kepler discovered its first rocky planet, dubbed Kepler-10b. However, this wasn’t rock you’d want to walk on since it was molten on the side of the planet closest to its star. But this was just the first of the many rocky planets that Kepler was to identify. In fact, by 2017 Kepler had identified 2,512 certain exoplanets.
Meanwhile, perhaps one of Kepler’s most intriguing discoveries came in December 2013. Kepler-22b was the first planet the telescope came across which was in the habitable zone, where the existence of liquid water would be possible on the planet’s surface. The planet was a bit more than twice the size of Earth, a common planetary diameter outside our solar system.
Then technical trouble hit the mission in May 2013. One of the four reaction wheels used to orientate the telescope had failed the year before – and now a second one had done the same. Indeed, the telescope needed a minimum of three working wheels to function. But it wasn’t the end of the road for Kepler as NASA scientists worked out other useful work it could still do, even with its limited capacity.
Kepler’s new mission, dubbed K2, utilized the pressure of sunlight to orientate the telescope. This meant looking at different sections of the night sky than previously scanned. As the mission continued, its founder William Borucki retired in July 2015 after 53 years with NASA. And just three years later, Kepler stopped sending data back to Earth.
What had happened to the Kepler space telescope that had stopped it transmitting data? Well, deep concern about data privacy is a commonplace on Earth in the computer age. Perhaps sentient beings on other planets felt uncomfortable about being scrutinized by Kepler. And maybe they’d decided to do something about it.
It’s an intriguing idea, that irked aliens might have curtailed Kepler with extreme prejudice. But it’s not what happened. In fact, the simple explanation for the end of the Kepler mission was that, after nine years of operation, the spaceship had finally run out of fuel. NASA shut down Kepler on November 15, 2018. Fittingly, that date was 388 years to the day since the death of Johannes Kepler.
Indeed, Kepler might be finished, but the hunt for planets capable of supporting life continues. NASA launched TESS, the Transiting Exoplanet Survey Satellite, in April 2018 into an orbit around Earth. TESS will carry on the work that Kepler started. So the hunt for planets that could support life in the Milky Way continues. We can only hope that no angry extraterrestrials will interfere.