NASA needs to extend the lifespan of a very special spacecraft: Kepler, the agency’s designated planet-hunter. Kepler is the only mission that can answer an existential scientific question that humans have: how common are other Earths?
Other earths – rocky planets with liquid water and a decent atmosphere – would have the raw materials for life as we know it. Kepler can tell us how many of these earth-like planets there are, bringing us one huge step to answering one of the most profound questions in science: are we alone? If we are, that’ll be one stunning answer. If we aren’t, that’ll be a different kind of stunning answer.
Either way, for my values, there is a moral imperative to answer this question. Finding life outside the earth could reshape the way humanity thinks about itself. The discovery of extraterrestrial life will mark an epoch in a way that even the moonshot did not. When (and it seems like when not if) we find another earth, the real space age will begin.
Right now, the drive to find life elsewhere in the universe is in trouble. Two other important exoplanet proposals – The Terrestrial Planet Finder and the Space Interferometer Mission – have been put on permanent hold. The delayed James Webb Space Telescope is eating up more and more of NASA’s science budget. And the general budgetary situation in Washington is bleak.
Kepler keeps chugging along towards the end of its initial 3.5 year lifespan. But it needs a little more time to complete the work it was sent up to do. Normally, those funds would be easy to come up with, but given the belt tightening in Washington, Bill Borucki, the missio’s longtime leader and promoter, is getting genuinely nervous. “There is a serious worry that Kepler’s funding might not be extended,” Borucki told me. That is to say, we might give up on the quest to find out how common Earths are in the universe for want of $20 million per year. For perspective, that’s the cost of fighting a few hours of the war in Afghanistan. Feel free to fill in your preferred partisan budgetary comparison. Any way you slice it, $20 million is nothing in the scheme of the Federal budget.
If we care about finding out if we’re alone in the universe – and we do – NASA and Congress have got to come together to find $20 million for this small mission. As University of California exoplanet scientist Greg Laughlin put it, “I do think that extending Kepler’s mission would be just about the very best way that NASA could spend money in these belt-tightening times.” I couldn’t agree more.
Let me tell you a little more about Kepler and why it needs to reach beyond its planned life. The Kepler spacecraft constantly watches a field of 145,000 stars looking for tiny variations in their brightness, which could indicate that an extrasolar planet has passed between the telescope and the star. After Kepler makes the initial spot, other telescopes can be pressed into service and astronomers can determine if a planet is, indeed, an earth-like planet in the habitable zone around its star.
It’s easy for Kepler to find planets circling close to their stars. That’s because Kepler is waiting for the planets to pass between us and the star. If that happens often – say, every couple months like the planet Mercury does – Kepler can quickly see that rhythmic dimming in the data and flag it as planetary candidate.
But think about a planet like Earth. An alien telescope pointed at Earth and employing Kepler’s method would only see us pass in front of our star once a year. It would take at least three years to start to see the pattern of the regular dimming of our sun’s light.
Alien astronomers looking for Earth, though, would have it easier than Kepler’s team looking for aliens. That’s because our star is unusually consistent in its brightness. Based on a variety of data, Kepler (and other) scientists assumed that the sun would be a fairly good measure of solar consistency for sun-like stars. But it’s not. Other stars’ data is noisier with greater variations in brightness.
“The reason we need to extend the missions is that we were surprised by the universe,” Borucki told me. “The way you build up the signal to noise ratio is to get more transits, so we need more time.”
So far, Kepler has discovered hundreds of planetary candidates, including 200 in the habitable zone after their latest data release on Friday. For now, most of the planets in the habitable zone are orbiting stars quite unlike our sun. They are smaller and cooler, so their habitable zones are closer in. We’ve found some planets that could harbor life (though we’re not sure) but that’s not exactly the point.
We need a census of these stars, not just individual candidates because the census is what will guide the future of planetary science. The next step in the quest to study earth-like planets is to peer into their atmospheres. By looking for certain elements in those atmospheres, we could read them for the telltale signs of life as we know it. But in order to pick the right instruments and properly size that telescope, we need to know how frequent the planets we’re looking for are. If they are everywhere, we can use different techniques (and won’t have to look as far) than if they are rare. And that’s the crucial knowledge that Kepler is in the process of giving us.
“If I find one earth-sized planet, I don’t really care,” Borucki said. “I gotta find enough to find the frequency so that we can go to the government and OMB and Europe and say, ‘We can now find atmospheres and see if there is ozone or oxygen in those atmospheres. Give us the money to to look!”
Borucki is passionate about Kepler. He published his first paper exploring how one would could look for exoplanets from a space-based observatory in 1985. 24 years later, Borucki saw his dream launch into space. For two and half long decades, Borucki had kept the faith through all kinds of trials and tribulations. Along the way, he picked up support from influential figures like Carl Sagan, but getting the mission funded took most of Borucki’s working life. You can imagine how it feels to be so close to completing his life’s work and dealing with the possibility of having Kepler shuttered before observations are complete.
All Borucki wants is four more years to deal with the unexpected variability of the universe. That’s $80 million total. If Kepler’s life doesn’t get extended, it will be one of those small bureaucratic losses that hardly anyone notices. There will be no street protests nor will Congressional investigators go knocking on anyone’s door. No one famous will care and it won’t be on CNN. Few jobs will be lost or created either way. But it will be yet another sign of the fraying of our democracy that we can’t fund (cheap) research into the most fundamental questions of human existence.
Based on recent observations, it appears highly likely that there are planets just like the Earth circling countless stars. Each may be a world as rich with life as our own. But they may not be for reasons we don’t yet understand. The least we can do for future generations is take the tiny steps necessary to start finding out.
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