The Leitmotif of this Quarter's SWG Meeting: Validation versus Confirmation

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The Kepler Science Team is scattered all over the US (excepting our two colleagues that help to run the Asteroseismology Consortium… from Denmark!).  Because of the distance, teleconferencing technology and platforms like webex for sharing computer desktops are as essential as the computers used to analyze the data.  But sometimes no technology can replace a room full of brainpower all attacking the same problem or contemplating the same question.  Maybe it’s just the smell of coffee and donuts or the inspiration derived from watching your colleague’s facial expressions.  The reality is that more gets done when we’re all in the same room.  So a few times each year, the team members pack up their laptops, hop on planes, and gather at the home institution of whomever happens to be taking his or her turn as the designated host.  This week, the team gathered at NASA Ames Research Center in Mountain View, California.  We call these our “Science Working Group” meetings,  more lovingly referred to as SWG (“swig”) meetings.
The first order of business is to hear status reports.  How is the instrument performing?  What does the budget look like going forward (as if we don’t already know the answer to that question)? What can we expect from future software releases and when can we expect them?  We learned that the spacecraft has been free of safe mode events for almost 8 months now.  This is very good news.  With more than a year of data under our belt, we’ve learned a lot about the performance of the instrument.  We see seasonal changes in the focus, for example, that are driven by the amount of sunlight striking the backside of the spacecraft.  Varying sunlight levels induce slow temperature changes that affect the focal length of the photometer.  The amplitude of the variation and its effect on the data is well within our tolerances.  There is no indication that we’ll lose any more modules.  
The various working groups then share what they’ve accomplished over the last months.  We heard a report, for example, from the Eclipsing Binary Working Group.  Their goal is to produce an updated binary catalog using four quarters of data within the next 6 months.  We are counting on them to tell us, statistically, how many binary stars of a given period and apparent brightness we expect to see — a number which helps us to understand how often we expect to find astrophysical signals in our data that mimic planet transits.  We must understand this number well because most of our planet candidates will NOT be confirmed in the traditional sense — by way of high precision radial velocity  measurements that give us the mass of planet.  The catalog of planets that Kepler produces will be probabilistic in that every candidate will have an associated likelihood that the planet interpretation is correct.  This is new territory we’re charting.  It will lead to a new type of discourse on exoplanets in our galaxy.  Someone wondered out loud how the public will react to the announcement of a new world… “with a 95% likelihood”.  As he asks the question, I’m picturing the fine print on my wireless phone bill, and I’m hearing the guy at the end of the commercial who uninteligibly rattles off the litany of horrible side-effects that said medication can produce.  That’s not a path we want to take.  We’ll be asking the public to contemplate the Universe in a statistical sense, and it might get ugly.
The team devoted a good fraction of its time discussing how these “likelihoods” will be computed.  There are challenges ahead.  A small committee will meet with the folks over at the Ames supercomputing facility to talk about ways to speed up the number crunching that will be required.  We’ll likely have to revisit our priorities for utilizing highly competitive time on telescopes like Keck, WIYN, and the MMT.  These discussion were kicked off by a talk that Jack Lissauer gave.  The title of his talk became the leitmotif of the meeting: “Validation versus Confirmation”.  We realize that there are issues we are only beginning to fully appreciate.  This does not discourage us.  To the contrary, it motivates us.  This is the scientific method at its best.  As we each head back to our home institutions, we know what to do.
Natalie Batalha
Deputy Science Team Lead, San Jose State University
For two days, members of the Kepler Science Working Group filled the air in the meeting room with descriptions of their work on the pixels, the pipelines, and the planets.   What impressed me most was the long hours and technical expertise everyone was contributing toward the still-absurd goal of finding and characterizing the first Earth-sized planets.
The folks on the team are critically examining and improving the instruments, software, and performance of every aspect of the Kepler mission, down to truly invisible minutia.   Some members are devoted to studying and minimizing electronics noise in the 94 megapixel light detector.  Others are optimizing spacecraft stability.  Some are dedicated to improving Kepler’s phenomenal photometric performance, working toward Kepler’s amazing goal of 20 parts per million.   And some are observing Kepler “Objects of Interest” at ground-based telescopes by night, attending the meeting by day, and then going back to the telescope each night, all to verify and measure the planet candidates Kepler has identified.   Just archiving all the information about the hundreds of “Kepler Objects of Interest” is a monumental task.
In the end, I felt fortunate to be a part of the camaraderie.  The meeting room was filled with a warmth of shared purpose.  Everyone is working with mutual appreciation of the enormous challenges and personal sacrifices needed to get the job done. And everyone was swept along by the unprecedented hope of placing our home planet in its proper cosmic context.
Geoff Marcy
Co-Investigator, UC Berkeley

It was exciting to see how much work has been accomplished and overwhelming to see how much work still needs to be done.  It was surpising to see so many new faces – the number of collaborators and contributors continues to grow – which is a very good thing.  On Wednesday, the day after the science team meeting, there was an all-day session to discuss the follow-up observations of individual candidates.  The participants  rolled up their sleeves and worked extremely hard all day.  By mid-afternoon it looked like the group had been locked up for a week – there were computer cords, styrofoam cups, jackets and sweaters, half-eaten doughnuts, empty soft-drink cans, and miscellaneous debris strewn everywhere, as people had not even left to get lunch.  The single-mindedness, dedication, and teamwork demonstrated by the scientists as they struggled to interpret the myriad observations on a plethora of candidate planets was a joy to behold.

Michael Haas
Science Office Director, NASA Ames Research Center


As a member of the Follow-up Observing Team, my days(and nights) are focused on collecting astronomical data that contributes to our understanding of the potential planets that Kepler finds. Since my work is focused on extending what Kepler finds, I forget that dozens of people are working on every detail of the Kepler project. Nearly all of the people at the SWG meeting need to complete their work, before I can do my own. From satellite communication, to public outreach, to nitty gritty pixel-level analysis, the amount of work that goes into Kepler is absolutely amazing.
Watching all the entire Kepler picture be painted was remarkable.
Howard Isaacson
Kepler Collaborator, UC Berkeley

Kepler Memorabilia – Original Kepler Star Plate

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And now, for a bit of Kepler history…

Over the holidays at the end of 1992, Lloyd Robinson, the CCD guru at UCO Lick in those days, had just retired and offered to set up a CCD system in the clean room in Santa Cruz to see what could be learned.  This star plate was a key component in that original setup.  
Original Kepler Star Plate

Original Kepler Star Plate
This star plate is an important Kepler relic. It was used in the first laboratory experiments to determine whether CCDs could produce very precise differential photometry.
When Jon Jenkins (Co-Investigator and Analysis Lead for Kepler) first set eyes on this plate in June, 2010, he recognized it immediately, even though he had never seen it before. This was because one of his first tasks for the mission was the analysis of an untold number of images from a variety of tests using this plate. These tests were invaluable in discovering all sorts of ways for test setups to go wrong, from sagging light bulb filaments to liquid nitrogen fills. Based on what was learned, more sophisticated laboratory test systems were developed using a variety of other star plates. This painstaking laboratory work culminated in the very successful Kepler Test Demonstration (KTD), which was instrumental in selling the Kepler Mission to NASA.

Kepler's Impact on the Coming Decade

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by Fergal Mullally

Support Scientist for the Kepler Science Analysis Systems

Kepler Science Office, NASA Ames Research Center

Work on astronomy largely ground to a halt this morning as the Decadal Review was published outlining the direction the field should take over the next 10 years.  With so many bright ideas floating around in astronomy, it can be hard to pick out the most interesting questions and the projects most likely to answer those questions.  So every 10 years, the nation’s astronomers come together to take a look at the big picture, and to look to the future.

The report starts by looking back at the dramatic progress made in the past few years. It’s hard to believe that a mere 20 years ago, we had no idea that dark energy existed, or whether planets existed around any star in the Galaxy other than our own.

But while we’ve climbed some impressive scientific mountains in the past twenty years, there are even more impressive peaks on the trail ahead. The Decadal Review considers “the most profound discovery in the coming decade may be the detection of potentially habitable Earth-like planets orbiting other stars”.  People have dreamed of that day ever since the times of the ancient Greeks.

This goal has two steps. First we need to find Earth-sized planets at just the right distance from their parent star, and then we will need to develop new technology to probe their atmospheres to search for oxygen, nitrogen, and the other elements we expect to find on a habitable, Earth-like, planet.

The second task is extraordinarily difficult. Earth-sized planets are small, far away, and hidden in the glare of their parent stars. A lot of development is still needed to build instruments to overcome those problems. Despite the challenges, the review places the challenge of imaging a habitable planet as a “Priority 1” goal, and Kepler as a key mission along the way.

In the meantime, Kepler is already hard at work answering the first question. Staring, unblinking, at 170,000 stars day after day, it will detect a minute change in brightness when a planet passes in front of the star it orbits. Before the decade is even half over, we hope to have found the first Earth-sized planet, and also to discover if such planets are commonplace, or rare.

The Decadal Review is mostly a dry, academic document with careful phrases and important caveats, but it rises to more poetic language when it attempts to describe the importance of this work. Hopefully, “one day, parents and children could gaze at the sky and know that a place somewhat like home exists around ‘THAT’ star”. That day  (or night!) is probably still more than a decade away, but it’s an awful lot closer than it was ten years ago. And so, here on the Kepler Team, we’re putting down our Decadal Reviews, and getting back to the work of bringing that day a little nearer.

For more information on the recently released 2010 Astronomy & Astrophysics Decadal Survey Report:

New Worlds, New Horizons in Astronomy and Astrophysics

National Academies Press (full report available here)

Kepler Sends Happy Birthday Wishes

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Kepler team members are sending in their well-wishes today, August 5, 2010, in honor of Neil Armstrong’s 80th birthday.  All comments have been added to a poster (available here) that the team is sending to him. Some are reproduced below.  Please join us in wishing Neil a…

                   Happy 80th Birthday!

“Neil — with warm wishes for a Happy Birthday — thank you for your contribution to space exploration.”

                – Roger Hunter

                   Kepler Project Manager, on behalf of the Kepler Team

“When I look at the data Kepler sends down, I realize that in these bytes is something new — something no human has ever seen before. And I pause to think of those before me who also looked at something new and took risks and made sacrifices so that ALL of humanity would see too. Through your eyes, we saw something extraordinary that changed our perspective forever, and I thank you for that. Happy 80th Birthday!”

                – Natalie Batalha

                  Deputy Science Team Director

“Apollo 11 was the inspiration for an untold number of people to pursue careers in engineering & the sciences. Back in the tumultuous 1960’s, this country emotionally needed the success you delivered. And we know you would be the first to say that you were just the visible part of the efforts of hundreds of thousands of people, but your coolness under stress during the mission and your grace and dignity since returning from the moon are all an inspiration. I am living the dream of being a NASA engineer because of you and and the people who worked around you back then. So beyond “Happy Birthday”, I want to say “Thank You”. “

                – Jon Cowart

                  NASA KSC & friend of Kepler

“Happy 80th Birthday Neil!  As we search for planets and their moons orbiting distant stars, I am often captured by the thought that the Universe must be filled with curious, awe-struck and awe-inspiring pioneers.  Thank you for being one of ours.”

                – Jessie Christiansen

                  Data Scientist

“I remember fondly listening to the conversation as you searched for a spot to land the LEM and watching your famous “small step”.  Your courage and actions were one of the reasons I chose a career in planetary sciences.  Happy 80th birthday!”

       – Jack Lissauer


Planets large and small: the Kepler planetary candidates in my TED Talk

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Dimitar Sasselov, Co-Investigator, Kepler Science Team, Harvard Smithsonian Center for Astrophysics

Two weeks ago I gave a talk at TED Global 2010 which was very well received, but caused confusion. I referred to past results from the NASA Kepler mission. Indeed, Kepler has not discovered Earth-like planets in habitable zones. We have not found Earth-size planets; at this time we have found only planet candidates – 706 of them as of June 15, 2010, based on only 43 days of data with 306 released and discussed in a paper by the Kepler team. Planet candidates are just that: “candidates”. A sizable fraction will turn out not to be planets, and we do not know what that fraction is yet.

So that was my challenge – Kepler measures planet sizes, while I wanted to talk about geochemistry. In just 18 minutes. So, the expected number of planets, size and Earth-like chemistry got confused, and created a misunderstanding.

The family of our Solar System planets seems simple when sorted by size: half of the planets are large (giants) and half of the planets are small (terrestrial). The giants contain a lot of light gases (hydrogen and helium) in their bulk composition while the terrestrial ones contain mostly heavier elements. Too much hydrogen and helium dilute the surface chemistry, while heavy elements and solid surfaces tend to concentrate it.  There is one planet in our Solar System where the chemistry has evolved to biochemistry and to a biosphere. In the search for life beyond Earth, the smaller planets are thus the favorite places to look.

The Kepler mission is designed to discover Earth-size planets by detecting and measuring their transits. The Kepler team collects additional information as it works to confirm a planet discovery, but one essential physical parameter Kepler provides is SIZE, the planetary radius. However, is “Earth-size” the same as “Earth-like”? And vice versa?

Kepler is capable of finding Earth-size planets in orbits of moderate temperatures. But most people consider the term “Earth-like” to mean that the planet has an atmosphere, liquid water on its surface, and a temperature conducive to life. In other words, “Earth-like” is often used to mean ‘habitable’. Therefore, Earth-size and Earth-like are certainly not the same. Take the example of Venus, an Earth-size planet whose surface will melt lead.

The term “Earth-like” planet creates confusion. To some scientists like me, who model planet interiors, the term “Earth-like” is a simple short-hand for a bulk composition like Earth’s. It emphasizes the broad difference between gas giants and terrestrial planets, as seen in our Solar System. However, I understand that this is not how it was interpreted by the majority of the media coverage. My definition allows for a whole range of planet sizes to be “Earth-like” planets. Thus, the question – what size planets might be “Earth-like”?, is more interesting. According to my definition, it involves the so-called “super-Earths” – planets larger in size and mass than the Earth, yet smaller than the giant planets. Many super-Earths are expected to have the same properties and potential for life as habitable Earth-size planets.

Kepler planetary candidates, like the 306 released this past June 15th, have estimated orbits and sizes. Sorted by apparent size, the majority of the candidates are found to be Neptune-size and smaller. This is the good news. As of today none of the candidates smaller than 2 Earth radii is in the habitable zone; their orbits are too small, which is why it was easier to spot them after just 43 days. Habitable planets will take a lot more time, as Kepler needs to observe more than one transit.

The first data release is an encouraging first step along the road to Kepler’s ultimate goals, specifically, to determine the frequency of Earth-size planets in and near the habitable zone. However, these are candidates, not systems that have been verified sufficiently to be considered as planets. The distribution of planet sizes may also change. It will take more years of hard work to get to our goal, but we can do it.

The TED Global conference is about ideas worth spreading to a general audience. In my TED talk I decided to discuss the idea that science seems to be at the threshold of a new revolution – of synthetic biology. Ironically, this is happening at the completion of the previous, Copernican, revolution. My point was that the two events are related, and that, tantalizingly, progress in synthetic biology may be accelerated by input from planetary science. This is the core of the project I lead and we call the Origins of Life Initiative (not associated with the Kepler Mission).

The Origins of Life Initiative makes connections between geochemistry and biochemistry. The Kepler mission helps our project by establishing feasibility: if solid planets are common, then we have a shot at trying our lab experiments. This works as long as the planets have geochemical cycles that determine their atmospheric signatures.  Hence, planets somewhat larger than Earth are more favorable (Sasselov & Valencia, Sci. American, Aug 2010). The Drake equation gives us an estimate of about 100 million such planets with habitable potential in the Milky Way galaxy. Kepler has not yet weighed in on this yet, but holds the potential to do so in the future.

Related links:

TEDGlobal Lecture
Dimitar Sasselov
: “On Completing the Copernican Revolution

Characteristics of Kepler Planetary Candidates Based on the First Data Set: The Majority are Found to be Neptune-Size and Smaller
Borucki, W. and the Kepler Team, submitted to Astrophysical Journal

Claims of 100 Earth-Like Planets Not True
by Clara Moskowitz @

Cosmic Log on
Millions of Earths? Talk causes a stir
by Alan Boyle 

Spacecraft Update & Are Kepler Seasons Similar to American Idol's?

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Well, folks, it’s been a long time since I’ve written, and there’s not been a lot of Kepler news in the news, as it were.  And I know people are wondering, “What’s going on?  Are we finding planets or what?”
So in a minute, I’ll tell you what’s going on.  But before I do, let me remind you where things stood when I last put out a notice.
We had been seeing ongoing problems with the star trackers that sometimes sent us to our Safe Mode.  And we had seen one of our 21 detector modules go dark on us.
We’ve done a lot of work on both these problems, and the spacecraft has been operating really nicely for four months now.  We still don’t know what is going on with the star trackers, but we’ve put in several layers of mitigation so even if they do act up a bit, we should be able to sail through it without interrupting science data collection.  For the detector that failed, we’ve narrowed down the failure to a particular circuit that seems likely to have blown a fuse onboard.  There’s nothing we can do to fix it, but the good news is that whatever caused the fuse to blow, we’ve been able to show that it was a very rare phenomenon, so we aren’t likely to see a bunch of detectors fail.
We uploaded a software patch to the vehicle and rebooted the flight processor and that went really well.  Our ground processing software is getting better.  It now searches for planets in the data automatically, and runs a variety of tests on what it finds, tossing out most of the false positives that masquerade as planets.  We’re now working on the last really big piece of the data processing puzzle, writing the software that will stitch together all our flight data and let us look for the long-period planets that will be most likely to support life.  Right now, the software runs on three months of data at a time.  Every three months we have to rotate the spacecraft to keep the solar panels aimed at the sun, and when we do, all our data sort of “hiccups” as all the stars are moved to different parts of the detectors.  Imagine it this way…
You set up a camera on a tripod and take 100 pictures of a bowl of fruit.  Then you turn the camera 90 degrees and take another 100 pictures.  Now, if you flip through the pictures rapidly, the first 100 will look nearly identical, and unless a fly landed on your fruit, it’ll probably put you to sleep.  Then all of a sudden everything will change a bit.  It’s the same bowl, same fruit, but it’s rotated 90 degrees and suddenly you’re awake and paying attention again.  But as you flip through the last 100 pictures, it goes back to being dull again.  No matter how careful you are with the camera alignment, and even if you rotate all the last 100 pictures so they are right side up, there will be that little glitch when you go from the first hundred to the second hundred.  And that little jump wreaks havoc on our software.  We’ve always known we would have to fix this, but it’s taken us a while to get there.  So there’s still more work to do before Kepler reaches it’s full potential.
But what has been going on in the mean time?  Well, this is where I’m going to try and make an analogy to American Idol.
Kepler is like a cosmic-scale American Idol, with 156,000 stars vying to be the winner, and show us their planets.
Like Idol, the early tryouts are a real trial, with a whole lot of bad candidates.  They might be interesting, entertaining, but not what we are looking for.  During these tryouts, we identify the most promising candidates, and hand out those coveted “tickets to Hollywood”.  In Kepler‘s world, these lucky contestants get a KOI number.  They become a “Kepler Object of Interest”.  It doesn’t mean they will win it all.  In fact, most of them will be eliminated by our “panel” before they ever get to face the “vote”.
In January, we announced 5 new planets.  Five new Idols from the first 10 days of data that we gathered.  You didn’t see the details of the Hollywood portion of that competition, only the results.
So yesterday, on June 15, we were obligated to make public, nearly all the data we collected from our first Quarter of operation. That first Quarter was a short one, because we didn’t start operations until most of the Quarter was gone, but still, it’s a big step beyond that first 10 days of data.  On June 15 we released the data for 43 days of operation, and the results of the “tryouts” from that period.  What will you see?  Another 5 planets?  Nope.  This time you’ll get a bit more insight into the Hollywood portion of the competition.  You’ll find that we issued something like 700 tickets to Hollywood!  And even if most of these are eventually sent home, there are still likely hundreds of winners, hundreds of planets within this group of contestants!  In fact, by the time we’re done with the competition, we’re likely to find that in the first 43 days of operation, Kepler has doubled the number of known Exoplanets!
Four hundred contestants will continue the competition within Kepler, and a new set of winners will be announced over the next six months.
Like American Idol, each new season takes a year to unfold.  But unlike American Idol, we start a new round every three months, and all our 156,000 contestants get to re-compete each Quarter.  All this really keeps our “Judges” busy.  But every year the winners are more and more talented, and eventually, we’ll end up with the real prize of the mission, Earth-size planets in the habitable zone that might sustain life!
So stay tuned for more news coming out every couple of months before another big announcement of Season 2 winners in January!

Charlie Sobeck, Deputy Project Manager

Kepler Website Wins Webby Award!

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Have you visitedKepler’s new website? <> It wasredesigned and launched back in January. Someone noticed! 

Kepler: A Search for Habitable Planets was selected as an Official Honoree for the Science category in The 14th Annual Webby Awards.

What’s a “Webby Award?”

The Webby Awards is theInternet’s most respected symbol of success. Webby Honorees, Nominees andWinners truly represent the best of the Web. The 14th Annual Webby Awardsreceived nearly 10,000 entries from all 50 states and over 60 countriesworldwide.

The Webby Awards ispresented by the International Academy of Digital Arts and Sciences, a650-person judging academy whose members include Internet co-inventor VintonCerf, R/GA’s Chief Bob Greenberg, “Simpson’s” creator Matt Groening,Arianna Huffington, and Harvey Weinstein.

Winners will beannounced on May 4th, 2010 and honored at a star-studded ceremony in New YorkCity on June 14th where they will have an opportunity to deliver one of theWebby’s famous five-word speeches with the world. Past Webby Award winners -and their speeches – include Al Gore (“Please don’t recount thisvote.”), Stephen Colbert (“Me. Me. Me. Me. Me.”), and MichelGondry (“Keyboards are full of germs.”) 

Photo of actual Webby Award

So now it’s time to turnthe spotlight on the talented folks who worked so hard to make it happen. Kudosto our website redesign team! Credit goes to Michael Greene for overseeing the project,to teams at JPL and Raytheon, including Joshua Rodriguez, Randal Jackson,Cornell Lewis, Joe Wieclawek, Maryia Davis and Ernest Koeberlein, Harman Smith,Randii Oliver, Erick Zwlaya ; and the Kepler EPO folks, Dave Koch, of NASAAmes, Edna DeVore, of SETI Institute and Alan Gould of Lawrence Hall ofScience, Berkeley.

Go Kepler!

Visit Kepler at Yuri's Night Bay Area!

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Kepler fans, if you live in California in the Bay Area, visit our booth (#121 in the hangar) at Yuri’s Night Bay Area tomorrow, Saturday April 10, noon to midnight. Visit for ticket prices, directions, musical guests, and more details on exhibits & entertainment.

Here are some highlights:

  • 300,000+ square feet of festival space and open tarmac
  • Two colossal aircraft hangars
  • Two stages of entertainment
  • Aerial demonstrations over the airfield
  • Large and small scale art and performances
  • Interactive art and technology exhibits
  • Ample parking and shuttle service
  • Access to mass transit
  • Full food concessions
  • Beer and wine gardens
  • Full VIP tent
Hope to see you there!

Kepler has people thinking…

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Comment written by Richard Dierking, an attendee at a Kepler teacher workshop in December 2009

Kepler has been the subject of about every science related publication I’ve seen recently. It’s really got people thinking.

A couple of months ago, I did a Kepler presentation with groups of GATE students at an Elementary school. At the end of these presentations, I always like to ask, “So, let’s say we do discover Earth-like planets – What then?” As usual, one of the kids answered, “well, we go there.” But it’s so far away I replied. During the presentation, I describe a light year and how far away even the closest stars are. However, this time, another kid that was intently following the whole presentation, answered, “well Mr. Richard, don’t worry about that! You just show us where they are, and we’ll figure-out a way to get there.” Wow, I enjoy sharing information with these kids.

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