Skip to main content

Kepler or not, we'll find life in space

By Meg Urry, Special to CNN
updated 11:22 AM EDT, Mon May 20, 2013
This diagram lines up planets recently discovered by Kepler in terms of their sizes, compared to Earth. Kepler-22b was announced in December 2011; the three Super-Earths were announced April 18, 2013. All of them could potentially host life, but we do not yet know anything definitive about their compositions or atmosphere. This diagram lines up planets recently discovered by Kepler in terms of their sizes, compared to Earth. Kepler-22b was announced in December 2011; the three Super-Earths were announced April 18, 2013. All of them could potentially host life, but we do not yet know anything definitive about their compositions or atmosphere.
HIDE CAPTION
Where life might live beyond Earth
Where life might live beyond Earth
Where life might live beyond Earth
Where life might live beyond Earth
Where life might live beyond Earth
Where life might live beyond Earth
Where life might live beyond Earth
<<
<
1
2
3
4
5
6
7
>
>>
STORY HIGHLIGHTS
  • NASA says planet-finding Kepler satellite directional equipment failing
  • Meg Urry says Kepler has found 2,700-plus exoplanets, some that may harbor life
  • She says NASA's resourceful scientists working to fix it; loss of its photometry would be huge
  • Urry: Yale prof has other method to find exoplanets; we're bound to eventually find signs of life

Editor's note: Meg Urry is the Israel Munson professor of physics and astronomy and chairwoman of the department of physics at Yale University, where she is the director of the Yale Center for Astronomy and Astrophysics.

(CNN) -- On Wednesday, NASA officials announced a serious problem with the Kepler satellite, the world's most successful planet-finding machine.

Since its launch four years ago, Kepler has found more than 2,700 possible planets orbiting stars other than our Sun, of which more than 100 have been confirmed. A few of these exoplanets resemble the Earth in size or mass.

Recently, three Earth-like planets were even reported to be in the habitable zone: close enough to the star they orbit that water is liquid, yet not so close that it is boiling. Planets with liquid water may well harbor life.

Meg Urry
Meg Urry

Now, the second of four of the Kepler spacecraft's reaction wheels, which aim the vessel's instruments, appears to have failed. It remains to be seen whether full repairs are possible.

For the spacecraft to point accurately, at least three reaction wheels are needed, corresponding to the three dimensions (up-down, north-south, east-west). The fourth wheel serves as a backup and provides cross-comparisons of data among the wheels. The first wheel failed last summer; now Kepler has too few reaction wheels to keep pointing with sufficient stability.

When a major component like a thruster fails on any spacecraft, operations software points the craft's solar panels toward the sun to ensure a continuous power supply.

Power is a satellite's lifeblood: Lose it and you lose communications, so the satellite can't be oriented properly or take data. Backup batteries allow the solar panels to be misdirected for a few hours or so, before all power is lost. But batteries drain quickly, so engineers design software to make sure that when something goes wrong, the spacecraft points in a direction that preserves power.

Urry: Three more homes for life in the universe?

Reaction wheels are spinning flywheels that carry "angular momentum," a term roughly analogous to the force that keeps a car coasting even when the driver's foot is off the gas.

Spinning objects keep spinning unless they transfer angular momentum to another object. For example, if a flywheel is commanded to spin more slowly (through an electric motor), the spacecraft will pick up spin to compensate. If the flywheel spins faster, the spacecraft will spin in the opposite direction. Increasing or decreasing the spin of a reaction wheel is therefore a way of pointing the spacecraft.

The Venus transit phenomenon
2009: Kepler telescope launch
CNN Student News STEM Connections

This may sound like a complicated way to make a telescope move, but the problem is, there is nothing in empty space to push on. To close a door, you push on it. This works because gravity holds you firmly on the ground, and your feet stay put because of friction with the floor.

If you pushed on an open door in space, it would push you in the opposite direction. In space, there is no standing still. So Kepler's reaction wheels are essential for pointing the spacecraft accurately and steadily.

Unfortunately, less stable pointing means less accurate photometry (the measurement of light from the star). Since Kepler finds planets by measuring the tiny dips in a star's brightness when a dark planet moves across the face of that star, less accurate photometry means Earth-like planets will be too hard to find.

Urry: A meteor and asteroid -- 1 in 100 million odds

NASA is trying to figure how to fix or work around the broken reaction wheels. It has done amazing things before; you don't have to be an optimist to think there is still a chance to turn Kepler around.

But the loss of a fully functional Kepler would be terrible. It has found more potential planets than any other facility or method. Kepler data have yielded an estimate of the total number of Earth-like planets in the Milky Way galaxy: at least 17 billion. That's an Earth-like planet around one in every six stars.

Fortunately, there are other ways to find planets than by detecting transits (the passage of a planetary body across a sun), as Kepler does. In fact, the first few hundred exoplanets were found by the "radial velocity" technique, which detects tiny motions of a star as it and its planets orbit one another.

A Yale astronomy professor, Debra Fischer, has pioneered clever improvements to this technique so that she can find 100 Earth-size planets, perhaps 10% of which might harbor life. (Hear the full story in Fischer's TEDx talk, "Why We Need to Find 100 Earths.")

Fischer is going after Earth-like planets in the habitable zone. After all, the discovery of life on another planet would cause a profound shift in our world view, akin to the Copernican shift from an Earth-centric to a Sun-centric world.

So when Fischer says we should be "the alien civilizations that explore other worlds," I say: With Kepler or without, it's only a matter of time until we find signs of life on other worlds.

Follow us on Twitter @CNNOpinion.

Join us on Facebook/CNNOpinion.

Read more space and science news at CNN Light Years

The opinions expressed in this commentary are solely those of Meg Urry.

ADVERTISEMENT
Part of complete coverage on
updated 4:47 PM EDT, Fri April 18, 2014
Jim Bell says NASA's latest discovery support the notion that habitable worlds are probably common in the galaxy.
updated 2:17 PM EDT, Fri April 18, 2014
Jay Parini says even the Gospels skip the actual Resurrection and are sketchy on the appearances that followed.
updated 1:52 PM EDT, Fri April 18, 2014
Graham Allison says if an unchecked and emboldened Russia foments conflict in a nation like Latvia, a NATO member, the West would have to defend it.
updated 9:11 AM EDT, Fri April 18, 2014
John Sutter: Bad news, guys -- the pangolin we adopted is missing.
updated 1:10 PM EDT, Sat April 19, 2014
Ben Wildavsky says we need a better way to determine whether colleges are turning out graduates with superior education and abilities.
updated 6:26 AM EDT, Fri April 18, 2014
Charles Maclin, program manager working on the search and recovery of Malaysia Flight 370, explains how it works.
updated 8:50 AM EDT, Fri April 18, 2014
Jill Koyama says Michael Bloomberg is right to tackle gun violence, but we need to go beyond piecemeal state legislation.
updated 2:45 PM EDT, Thu April 17, 2014
Michael Bloomberg and Shannon Watts say Americans are ready for sensible gun laws, but politicians are cowed by the NRA. Everytown for Gun Safety will prove the NRA is not that powerful.
updated 9:28 AM EDT, Thu April 17, 2014
Ruben Navarrette says Steve Israel is right: Some Republicans encourage anti-Latino prejudice. But that kind of bias is not limited to the GOP.
updated 7:23 PM EDT, Wed April 16, 2014
Peggy Drexler counts the ways Phyllis Schlafly's argument that lower pay for women helps them nab a husband is ridiculous.
updated 12:42 PM EDT, Wed April 16, 2014
Rick McGahey says Rep. Paul Ryan is signaling his presidential ambitions by appealing to hard core Republican values
updated 11:39 AM EDT, Wed April 16, 2014
Paul Saffo says current Google Glasses are doomed to become eBay collectibles, but they are only the leading edge of a surge in wearable tech that will change our lives
updated 2:49 PM EDT, Tue April 15, 2014
Kathleen Blee says the KKK and white power or neo-Nazi groups give haters the purpose and urgency to use violence.
updated 7:56 AM EDT, Wed April 16, 2014
Sen. Sheldon Whitehouse and Rep. Henry Waxman say read deep, and you'll see the federal Keystone pipeline report spells out the pipeline is bad news
updated 7:53 AM EDT, Wed April 16, 2014
Frida Ghitis says President Obama needs to stop making empty threats against Russia and consider other options
ADVERTISEMENT
ADVERTISEMENT
ADVERTISEMENT
ADVERTISEMENT