Success: Kepler Lifts Off to Look for Other Earths

by Anne Minard on March 6, 2009

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Artist's rendering of the Kepler mission. Credit: NASA

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Kepler as it appeared moments prior to launch in Florida. Credit: NASA

NASA’s Kepler mission lifted off without a hitch just before 11 p.m. local time Friday from Cape Canaveral Air Force Station in Florida. 

The launch was a bit of a nail-biter, coming on the heels of last week’s failure of the Orbiting Carbon Observatory, which plummeted into the ocean when its fairing malfunctioned. But everything for the Kepler launch — from the weather to the countdown — went flawlessly. At five minutes to launch, Kepler’s rockets sent ribbons of smoke into Florida’s 65-degree Fahrenheit (18-degree Celsius) nighttime air under perfectly clear skies. With 30 seconds left, confirmation commands were exchanged with practiced precision. The casing (called the fairing) fell off with grace, and three minutes into the flight, the craft was cruising away from Earth at nearly 7,000 miles (11,265 kilometers) per hour. Each launch event happened within three seconds of its predicted time. 

Kepler’s engines shut down at 11:45 p.m. U.S. eastern time, and the craft achieved separation just before midnight, about 62 minutes after launch. Now, for the next three and a half years, Kepler will trail Earth in orbit and stare at a single patch of sky in the  Cygnus-Lyra region of the Milky Way.

Kepler fires the imagination, as it could finally address the age-old question of whether we Earthlings are alone. William Borucki, NASA’s principal investigator for Kepler science, spoke about the mission at a recent NASA press conference and said if Kepler spies Earth-like planets in the habitable zones of other stars, “life may well be common throughout our universe. If on the other hand we don’t find any, that will be another profound discovery. In fact it will mean there will be no Star Trek.”

The $500 million Kepler mission will spend three and a half years surveying more than 100,000 sun-like stars in Cygnus-Lyra.  Its telescope is specially designed to detect the periodic dimming of stars that planets cause as they pass by. 

By staring at one large patch of sky for the duration of its lifetime, Kepler will be able to watch planets periodically transit their stars over multiple cycles, allowing astronomers to confirm the presence of planets and use the Hubble and Spitzer space telescopes, along with ground-based telescopes, to characterize their atmospheres and orbits. Earth-size planets in habitable zones would theoretically take about a year to complete one orbit, so Kepler will monitor those stars for at least three years to confirm the planets’ presence.

Astronomers estimate that if even one percent of stars host Earth-like planets, there would be a million Earths in the Milky Way alone. If that’s true, hundreds of Earths should exist in Kepler’s target population of 100,000 stars.

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  • McRude

    Even if Kepler doesn’t find any Earths, that could just mean they chose the wrong spot in the sky.

    I can’t WAIT till we find another habitable zone planet and or life on Mars ‘cuz I’m getting really tired of hearing this crap of Are we alone? Find SOMETHING already.

    To think we are special in this Universe is egotistical, vain and plain ignorant….

  • Frank Glover

    “Trippy, project Orion promised the same some 40 years ago. It didn’t happen, and many think it couldn’t happen.”

    Orion’s problems were more political than technical. Wehn people get bent out of shape over launching probes that contain only enough plutonium for an RTG, you know that a system requiring multiple nuclear detonatons isn’t going anywhere. And the Nuclear Test Ban Treaty made no exceptions for nuclear detonatons in space for propulsive purposes.

    We haven’t been to the Moon since 1972, because Congress wasn’t interested in supporting large manned space projects , after the initial Apollo successes. We han nuclear (that word again) thermal rocket technology mostly in hand, but ended the NERVA project because the Mars and advanced Lunar missions where they would’ve been most useful, noted, wern’t going to happen.

    Some things are currently out of our technological reach, but some things don’t happen because of money/politics.

    Simple as that.

  • Ross

    A couple of nitpicky things:

    1) If the estimate of the stars in the milky way is somewhere around 400 billion, and if 1% of the stars has an earthlike planet around it, there could be … 4 billion earthlike planets in our galaxy alone, not 1 million. But if we look at sunlike stars only, and the estimate of 10% of the stars in our galaxy are sunlike, then the number of earthlike planets, at 1% would be: .01 x .10 x 400 x 10^9 = 400 million earthlike planets. I’m wondering where they got the 1 million number from …

    2) Kepler won’t be just looking at sunlike stars. In the field of view, there will be many small red dwarf stars, and any planets in the habitable zones of those stars won’t take 1 year or 3 years to be verified. We could be getting results a lot earlier if we count those.

    3) Jupiter sized planets in the habitable zone could potentially have habitable moons. If we find 0 earthlike planets in the habitable zone, but several or many jupiter sized ones (we’ve already found a few of those), then the potential for habitable worlds still exist, even without exact copies of earth.

    4) The section of the sky they are looking at contains 4 to 6 million stars, or about .001 % of the stars in our galaxy. The number of stars in that sample that are edge on to us (so we can see the light dimming as a planet passes in front of us) is estimated to be about 100000. Can we get a statistically significant estimate from such a small sample, significant enough to conclude that if we don’t find any earthlike planets, that there aren’t any and we are then alone?

  • Element92

    Great that Kepler launched OK without a glitch. I think we’ll find terrestrial planets are “as common as muck”.

  • bse5150

    McRude, remember just 15 years ago, there were still a lot of the most INTELLIGENT in the scientific community telling us there were no other planets outside our solar system.

  • http://mysite.verizon.net/vzepp2a0/ Kevin F.

    3) Jupiter sized planets in the habitable zone could potentially have habitable moons. If we find 0 earthlike planets in the habitable zone, but several or many jupiter sized ones (we’ve already found a few of those), then the potential for habitable worlds still exist, even without exact copies of earth.

    Absolutely. I’m always befuddled on the people who leap on things which at the moment are completely untestable like panspermia – but this obvious possibility of an earthlike world orbiting a gas giant gets practically no coverage. Can you imagine what the sentient beings evolving up under a gas giant like Jupiter’s take would be on the planet and it’s forever changing patterns? THAT’S a fun mental playground.

  • Lawrence B. Crowell

    I did a calculation some time back to estimate how many Earth-like planets there might be. I got about 10,000. This was based on a Bayesian analysis on Lyapunov exponents for putative 1AU planets that are modeled to exist in known extrasolar G-class systems. A close Jovian would tend to rattle the orbit and cause it to chaotically shift too much.

    Of course this does not say much about moons around ~ 1AU Jovians.

    The galaxy has about 300 B stars, and 3% of them are stars comparable to the sun, or in the near G category of F or K class. The statistics seemed to indicate that a pretty small fraction of stellar systems are comparable to outs. Of course this is based on incomplete evidence, as most techniques favor finding close in or torch Jovian planets.

    Kepler will give a clearer picture of things and better estimates on the number of possible bio-active planets out there.

    Lawrence B. Crowell

  • miguel

    can’t wait for first pictures to be shared. Unfurtuanally, looking at a planet 7 billion light years will let us see how the planet was 7 billion years ago. Finding another earth will make me really happy though, I stay really positive; after all this is a 95 megapixel camera!

  • mike

    Have read that when our sun becomes a red giant then Titan will have the heat to evolve into habitability so I assume that a star’s habitable zone varies with the age, type, and size of the star and thus the orbit of objects within that zone may be quite different than our earth’s orbit. Am I wrong, or shouldn’t we be focusing our planetary and moon search among habitable zones in all probable life supporting stars, not just those similar to our sun? MOK

  • Geoff of Essex

    (McRude Says: March 8th, 2009 at 12:44 pm “Even if Kepler doesn’t find any Earths, that could just mean they chose the wrong spot in the sky”).

    As the Chinese say, “the longest journey begins with the first step”.
    Kepler is a first of a kind type mission – its search area is reported to be a 10 degree by 10 degree square of the sky. That represents 1 part in 648 as in 180 x 360 = 64800 versus 10 x 10 = 100; or about 0.15% of the sky’s surface area. If nothing is found in that patch there are another 647 similar sized patches of the sky to look in. Not all are equally likely to be suitable for searching in. Doubtless, some kind of analysis, such as led to the picking of this “patch of sky in the Cygnus-Lyra region of the Milky Way” will turn up the better “patches” for the next or the next or the … mission to look over and get “lucky”.

    However, if the nearest “Earth-like” planet is 50 or 500 or 5000 light years away, no one is going there anytime soon, so what’s the hurry.

    As another poster (miguel Says: March 9th, 2009 at 10:15 am) commented these objects are as they were 50, 500 or 5000 years ago, and if one-way trips take many multiples of the distance in years to get there – who is to say what condition they would be in when anything we can send gets there! Any results, messages etc would then take a similar time to the distance in years to get back.

  • Ace

    Another important fact to remember is that if Kepler only detects planetary transits, it means it can look directly at a star with planets but not detect them if they do not pass between the star and the probe (i.e., if Kepler is looking at the star’s north or south pole). If it is taking radial velocity measurements as well, that would be much more likely to detect new planets.

    And 7 billion light years is a gross exaggeration, the Milky Way is only 100,000 light years across. I don’t know about the Cygnus-Lyra region, but there are plenty of stars with planets that are under 100 light years away, such as the famous Gliese 581 (Ymir).

  • Daniel

    Just a couple of comments to clarify things:
    - Kepler only monitors about 100,000 “sun-like” stars (i.e. late-type dwarf stars). These stars have been preselected as targets, since Kepler is not able to send back the entire image from its 95Mpix camera (not enough bandwidth!).
    - Kelper targets will be quite bright (V<15), and so it is unlikely they will be more than 3000 light years away. However VERY few would be closer than 100 light years away.
    - The chance of an earth-like planet transiting a star of known radius can be worked out geometrically. it is quite low… only a few percent, because the probability drops as the planet is further from its host star.
    - since a few percent of earth-like planets transit, 100,000 will be statistically sufficient as it provides a few 1000 systems with the potential for transits (if they host planets!).

    Good luck Kepler!

  • george jarrett

    thank you, McRude; I feel the same way. I wish these egostical so-called-scientists and wannabes, like Glover would realize that we are not special. We dont have to send 1/2 BILLION$ ROBOTS into space to know that we are not alone. The cosmos are just too enormous. We’d have to be vain to the core to assume that just because our little machines does not know where to search and that our little robots cannot detect life as we know it…. that we shall assume there is no other life…PLEASE! GET REAL! if we could see some of the life that God has placed out there, it would frighten our little ancient minds out of there skulls. Maybe its best to settle for life here on Earth, feed the hungry, save the whales, nourish the forests, clean the oceans and the atmosphere… there’s a good start at finding more life for you.

  • UKDave

    two points:

    1. Larger objects are generally far less common than smaller ones, on that basis alone I would expect earth sized objects to be more common than the already found Jupiter + sized planets, (and less common than mercury sized bodies). So I’m expecting Kepler to find many ‘Earths’ out there!

    2. However, If Kepler was 20 light years out there, and looking back into our own solar system – would it consider Venus (as hostile a planet as you can imagine!) a potentially habitable world? Would it be capable of resolving close orbital/mass partners Earth and Venus or would it miss one or both of them?

  • Jon Hanford

    UKDave touches on an aspect of the mission glossed over in several articles & mistakenly repeated in most of these replies. Kepler will be looking for Earth-SIZED planets and not necessarily Earth-LIKE planets. As UKDave alluded to, Venus & Earth share similar diameters & masses, but Venus is anything but Earth-like. Of course, Keplers’ discovery of Earth-sized planets will allow intense follow-up by ground & space-based telescopes to tease out any info regarding the atmospheric composition & temperature of these planets. But Earth-sized planets are not necessarily Earth-like.

  • Muhammad Tahir Iqbal

    im excited that finally something took off the ground which will stay in the orbits of moon and earth. And hopes are high. Kepler is the biggest hope for Astronomers and for us who r seeking for the answers; that r v really alone?
    Let’s c wat does Kepler do in it’s journey?

  • Muhammad Tahir Iqbal

    I wud also add; if Kepler is watching the Milkyway patch targeting Cyngnus-Lyra constellations, then shud we assume that life do exist in Vega, As in Jodie Foster’s movie “CONTACT”. She caught the signals and Hadden helps her to reach him.
    Are all scientists are convinced that there’s a minor or maxim chance of habitants in Vega in Lyrae. Is this the reason they chose for Cygnus-Lyrae?

  • Geoff of Essex

    Muhammad Tahir Iqbal Says: March 10th, 2009 at 7:15 am
    “Are all scientists convinced that there’s a minor or maximal chance of habitants in Vega in Lyrae. Is this the reason they chose for Cygnus-Lyrae?”

    The reasons for selecting one patch of sky rather than another would have little to do with expectations of life – or otherwise on the part of the selectees. After all conducting science and/or research based on “preconceived ideas” about what is <> is neither science nor research. Why conduct research, if you “know” the answer before hand, that is not research!

    The reason for selecting this region appears to be on the so-called Goldilocks principle that the search area should not be too crowded (looking towards the Galactic Centre), nor too sparse (looking towards the Galactic Poles). Taking the “happy” medium of looking towards either 45 degrees above/below the Galactic Equator puts the search area field of view where the stars are not on top of each other (from the line of sight perspective) and also too separated that the field-of-view is being wasted.

    Also looking for a Galactic Habitable Zone “Goldilocks” region, it makes sense to look at the local Galactic neighbourhood first, rather than half-way across the galaxy. The sun is located about 27,000 light years from the centre so, if you restrict the initial searches to say ± 5,000 light years from home and do your statistics on that region, this can then be applied (with some confidence) to further areas of search in later missions. Too close to the centre and the cosmic ray radiation may be too high, plus increased risk of supernova blasts and reduced metallicity in stars; too far from the centre out towards the edge and the inverse is thought to be true. Why not stick (at least initially) to the local regions in the mid-ranges of the galaxy away from the bulge and in some of the nearer spiral arms, etc.

  • Geoff of Essex

    Regarding my previous comment, the “” word was meant to be “known” – hope this clariies matters.

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