Skip to main content

Kepler or not, we'll find life in space

By Meg Urry, Special to CNN
May 20, 2013 -- Updated 1522 GMT (2322 HKT)
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
July 24, 2014 -- Updated 1349 GMT (2149 HKT)
Patrick Cronin and Kelley Sayler say the world is seeing nonstate groups such as Ukraine's rebels wielding more power to do harm than ever before
July 23, 2014 -- Updated 2205 GMT (0605 HKT)
Ukraine ambassador Olexander Motsyk places blame for the MH17 tragedy squarely at the door of Russia
July 24, 2014 -- Updated 1142 GMT (1942 HKT)
Mark Kramer says Russia and its proxies have a history of shooting down civilian aircraft, often with few repercussions
July 24, 2014 -- Updated 1853 GMT (0253 HKT)
Les Abend says, with rockets flying over Tel Aviv and missiles shooting down MH17 over Ukraine, a commercial pilot's pre-flight checklist just got much more complicated
July 24, 2014 -- Updated 1317 GMT (2117 HKT)
Mark Kramer says Russia and its proxies have a history of shooting down civilian aircraft, often with few repercussions
July 24, 2014 -- Updated 1637 GMT (0037 HKT)
Gerard Jacobs says grieving families and nations need the comfort of traditional rituals to honor the remains of loved ones, particularly in a mass disaster
July 24, 2014 -- Updated 1413 GMT (2213 HKT)
The idea is difficult to stomach, but John Sutter writes that eating dog is morally equivalent to eating pig, another intelligent animal. If Americans oppose it, they should question their own eating habits as well.
July 23, 2014 -- Updated 1630 GMT (0030 HKT)
Bill van Esveld says under the laws of war, civilians who do not join in the fight are always to be protected. An International Criminal Court could rule on whether Israeli airstrikes and Hamas rocketing are war crimes.
July 23, 2014 -- Updated 1205 GMT (2005 HKT)
LZ Granderson says Ronald Reagan went horseback riding and took a vacation after the Korean Air Crash of 1983. So why does the GOP keep airbrushing history to bash Obama?
July 23, 2014 -- Updated 1338 GMT (2138 HKT)
Aaron Miller says Kerry needs the cooperation of Hamas, Israel, Egypt and others if he is to succeed in his peacemaking efforts
July 23, 2014 -- Updated 1251 GMT (2051 HKT)
Errol Louis says the tragic death of Eric Garner at the hands of the NYPD has its roots in the "broken windows" police strategy from the crime-ridden '80s.
July 23, 2014 -- Updated 1408 GMT (2208 HKT)
Gordon Brown says the kidnapped Nigerian girls have been in captivity for 100 days, but the world has not forgotten them.
July 23, 2014 -- Updated 1127 GMT (1927 HKT)
Ruben Navarrette says Texas Gov. Rick Perry is right to immediately send 1,000 National Guard troops to the U.S.-Mexico border in response to the border children crisis.
July 22, 2014 -- Updated 1356 GMT (2156 HKT)
Ukraine's president says the downing of MH17 was a terrorist act, but Richard Barrett says it would be considered terrorism only if it was intentional
July 22, 2014 -- Updated 2015 GMT (0415 HKT)
Robert McIntyre says the loophole that lets firms avoid taxes should be closed
July 22, 2014 -- Updated 1535 GMT (2335 HKT)
Jeronimo Saldana and Malik Burnett say Gov. Perry's plan to send National Guard to the border won't solve the escalating immigration problem.
July 22, 2014 -- Updated 1742 GMT (0142 HKT)
Sally Kohn: The world's fish and waters are polluted and under threat. Be very careful what fish you eat
July 22, 2014 -- Updated 1242 GMT (2042 HKT)
Les Abend says threat information that pilots respond to is only as good as the intelligence from air traffic controllers. And none of it is a match for a radar-guided missile
July 21, 2014 -- Updated 1235 GMT (2035 HKT)
Frida Ghitis: Anger over MH17 is growing against pro-Russia separatists. It's time for the Dutch government to lead, she writes
July 21, 2014 -- Updated 1227 GMT (2027 HKT)
Julian Zelizer says President Obama called inequality the "defining challenge" of our time but hasn't followed through.
July 21, 2014 -- Updated 1157 GMT (1957 HKT)
Gene Seymour says the 'Rockford Files' actor worked the persona of the principled coward, charming audiences on big and small screen for generations
July 21, 2014 -- Updated 1417 GMT (2217 HKT)
Daniel Treisman says that when the Russian leader tied his fate to the Ukraine separatists, he set the stage for his current risky predicament
July 18, 2014 -- Updated 1642 GMT (0042 HKT)
Andrew Kuchins says urgent diplomacy -- not sanctions -- is needed to de-escalate the conflict in Ukraine that helped lead to the downing of an airliner there.
July 19, 2014 -- Updated 0150 GMT (0950 HKT)
Jim Hall and Peter Goelz say there should be an immediate and thorough investigation into what happened to MH17.
July 18, 2014 -- Updated 1507 GMT (2307 HKT)
Pilot Bill Palmer says main defense commercial jets have against missiles is to avoid flying over conflict areas.
July 20, 2014 -- Updated 1755 GMT (0155 HKT)
Valerie Jarrett says that working women should not be discriminated against because they are pregnant.
July 21, 2014 -- Updated 1953 GMT (0353 HKT)
David Wheeler says the next time you get a difficult customer representative, think about recording the call.
July 18, 2014 -- Updated 1933 GMT (0333 HKT)
Newt Gingrich says the more dangerous the world becomes the more Obama hides in a fantasy world.
July 18, 2014 -- Updated 1011 GMT (1811 HKT)
Michael Desch: It's hard to see why anyone, including Russia and its local allies, would have intentionally targeted the Malaysian Airlines flight
July 17, 2014 -- Updated 1914 GMT (0314 HKT)
LZ Granderson says we must remember our visceral horror at the news of children killed in an airstrike on a Gaza beach next time our politicians talk of war
July 17, 2014 -- Updated 1206 GMT (2006 HKT)
Sally Kohn says now the House GOP wants to sue Obama for not implementing a law fast enough, a law they voted down 50 times, all reason has left the room.
July 17, 2014 -- Updated 1214 GMT (2014 HKT)
A street sign for Wall Street
Sens. Elizabeth Warren, John McCain and others want to scale back the "too big to fail" banks that put us at risk of another financial collapse.
July 17, 2014 -- Updated 2016 GMT (0416 HKT)
Newt Gingrich writes an open letter to Robert McDonald, the nominee to head the Veterans Administration.
July 18, 2014 -- Updated 1601 GMT (0001 HKT)
Paul Begala says Dick Cheney has caused an inordinate amount of damage yet continues in a relentless effort to revise the history of his failures.
July 18, 2014 -- Updated 1404 GMT (2204 HKT)
Kids who takes cell phones to bed are not sleeping, says Mel Robbins. Make them park their phones with the parents at night.
July 24, 2014 -- Updated 1625 GMT (0025 HKT)
Buzz Aldrin looked at planet Earth as he stood on talcum-like lunar dust 45 years ago. He thinks the next frontier should be Mars.
July 16, 2014 -- Updated 1804 GMT (0204 HKT)
Mark Zeller never thought my Afghan translator would save his life by killing two Taliban fighters who were about to kill him. The Taliban retaliated by placing him on the top of its kill list.
July 17, 2014 -- Updated 1518 GMT (2318 HKT)
Jeff Yang says an all-white cast of Asian characters in cartoonish costumes is racially offensive.
July 17, 2014 -- Updated 0124 GMT (0924 HKT)
Gary Ginsberg says the late John F. Kennedy Jr.'s reaction to an event in 1995 summed up his character
July 16, 2014 -- Updated 1641 GMT (0041 HKT)
Meg Urry says most falling space debris lands on the planet harmlessly and with no witnesses.
ADVERTISEMENT