August 12th: Kepler Keeps on Giving

Date: August 12, 2010

Title: Kepler Keeps on Giving


Podcasters: Roz Brown and John Troeltzsch

Organization: Ball Aerospace & Technologies Corp. –

Description: It’s been more than a year since the planet-hunting Kepler mission began its search for Earth-like planets. A stream of data is delivered regularly to Kepler scientists as observations continue round-the-clock during the three year mission. What’s the latest?

Bio: Ball Aerospace & Technologies Corp. supports critical missions of important national agencies such as the Department of Defense, NASA, NOAA and other U.S. government and commercial entities. The company develops and manufactures spacecraft, advanced instruments and sensors, components, data exploitation systems and RF solutions for strategic, tactical and scientific applications. John Troeltzsch is the Ball Aerospace program manager for the Kepler mission. Roz Brown is the Media Relations Manager for Ball Aerospace.

Today’s sponsor: This episode of “365 Days of Astronomy” is sponsored by Elizabeth Fracek, and is dedicated to my own personal shining star, my fiancé Robert. Thank you so much for exploring not only the stars with me, but also the depths of our hearts. I love you in all ways possible, and some that aren’t.


Roz: I’m Roz Brown. Kepler – the first space telescope designed to find Earth-size planets in the habitable zone of sun-like stars, has been on orbit for more than a year now. So what has it discovered? Kepler is using a photometer that’s continuously observing some 150,000 stars located between 600 and 3,000 light-years away. It’s looking for the faint dimming of a star that occurs when an orbiting planet passes in front of it. Three such dimmings equally spaced suggest you have a planet. If the star is approximately the same size as our sun, it could be the center of a planetary system much like our own—and that planet could be habitable.
I’m here with John Troeltzsch, the Kepler program manager at Ball Aerospace.

Roz: John, let’s start with the equipment. As we talk, it’s been a year and five months since Kepler was launched. Ball built the spacecraft and the photometer that is looking at the stars – how is everything working so far?

John: Very well. Kepler operations have become very routine. When you think about the mission, the purpose is really to stare at the same part of the sky continuously. So, we stare for a month, then we rotate and point to Earth and send the data down and every three months we roll the spacecraft 90 degrees to keep the sun on the solar panels. So, overall we take data, we downlink the data, and we keep the sun on the solar panels. It is a very simple operation.

Roz: So, I understand that we just had the summer roll-over and now we’re in the summer altitude?

John: That’s right and this is the first time we’ve been at the same orientation for a second time. During the first year each time we rolled, we actually put stars on a different part of the focal plane than they had been previously but now we’re back into sync with where we were the first quarter after we launched. So, we’re taking data kind of at the same pointing which is very good because it allows us to check the equipment and look at the repeatability over a year.

Roz: O.K. So if things are settling into a routine, what sort of challenges do you face?

John: Fortunately there aren’t a lot of challenges. The detectors and optics continue to work very well doing what they’re supposed to – by capturing the light from the stars we’re monitoring and the pointing is absolutely exquisite. You know, photometry requires very stable pointing and Kepler is proving to be the best photometer ever built, due to its field of view, stability and sensitivity. We’re able to look at the same part of the sky, without moving, for long, long, long periods of time. In fact, we measure our drift in thousandths of a pixel.

Roz: We were told when Kepler launched, that we wouldn’t find out overnight if it had discovered habitable planets…but we did find out in January of this year at the American Astronomical Society (AAS) meeting that Kepler had identified five new exoplanets….appropriately named 4b, 5b, 6b, 7b and 8b. What else have we learned in the past 17 months?

John: Finding those five planets really was the proof of Kepler’s concept. You know, we got up there and that was done with the first 30 days of data, but since that time we’ve taken a lot more data – in fact – we have lots and lots of candidates in the pipeline right now. Those candidates are identified and we put them into a follow-up observing program where we go off and make sure we don’t have false alarms. So, right now we have found a whole bunch of new candidates and they’re in this follow-up observing pipeline so that we can confirm whether or not they’re planets or that we might be seeing star spots or other things. We take announcements of planets very seriously so we’re very careful not to release something that we haven’t confirmed is a real planet.

Roz: How do you go about that – how do you follow-up to know you’ve found a real planet?

John: Well, once we’ve identified something in the light curve that looks like a planet, we used ground-based observatories to go out and zero-in on the star and measure things like radio velocity – that’s how the planet and star wobble as they go around each other – and look at the light curves from the ground-based observers to verify that we really have a planet. One of the real challenges we have is the very small planets – we are seeing some planets that are on the small end of things – it’s very hard to use the radio velocity to detect the planet, so we’re also looking at how to use Kepler data to confirm its own discoveries.

Roz: So, it’s a three-and-a-half year mission and we’re about a year and a half in – what else can we expect next?

John: NASA released the first 45 days of Kepler data in June, to the public. The astronomical community responded by downloading over 4 terra bytes of data and more than 30 million unique data sets. This data is being analyzed by astronomers all over the world to look for signs of planets that the Kepler science team might have missed.

Roz: So explain a bit more about who is making the Kepler observations. I know on Hubble, there were hundreds of astronomers and scientists accessing this info – so who gets to see the good stuff first on this one?

John: The Kepler science team put an awful lot of work into getting Kepler on orbit and getting the pipeline built so that they could analyze the data so they’re allowed to look at the data the first year after it’s taken. In fact, sometimes they’re allowed longer than a year depending on the complexity of the data they’re trying to analyze, so they get the first shot at the data and are able to look for planet and then the data is released to the general observing community and they come in and look for things the Kepler team might have missed or look at the data in a different way, so it really gives a chance to look at and exploit all the data Kepler’s taking. In fact, a lot of the scientists aren’t looking for planets – they’re looking at the physics of stars. And, we recently had a conference in Europe where over 400 scientists in Europe met to talk about the exquisite photometry that Kepler’s providing, and what they can learn from stellar physics by looking at that data. So, right now the Kepler science team is looking at the order of a thousand candidates for follow-up observing. That’s an awful lot of candidates and a lot of those may not turn out to have planets but it gives you an idea of how many positive signatures we’re seeing. Of those thousand candidates, they cover a broad range – from big planets to small planets – hot planets to temperate planets so we’re really seeing a vast array of different kinds of exoplanets. There’s no question Kepler is revolutionizing our understanding of exoplanets. The current catalog of over 450 exoplanets will be significantly expanded in the next six months as these candidates are observed and followed-up and we make our and we make our releases of the scientific papers.

Roz: So from everything we read Kepler will basically re-write the catalog on exoplanets.

John: There’s no question Kepler is revolutionizing our understanding of exoplanets. The current catalog of 450 exoplanets will expand dramatically over the next six months as all of these candidates we have in the observing program get confirmed or in some cases rejected.

Roz: So those of us who are eagerly awaiting news about the discovery of habitable planets – where we know ET’s cousin is sitting in a hot tub waiting for us to arrive – what can we expect in the next six months?

John: The Kepler science team is in the process of looking at all these candidates and writing papers. We would expect to publish a series of new papers over the six months. There’s going to be the first Kepler science conference in December – at which point the scientists will have a chance to come and look at some of the discoveries; and in addition – the AAS meeting that’s planned for January will have a special session dedicated to Kepler discoveries.

Roz: When Kepler was launched it was billed as a three-and-a-half year mission. Is there any chance that it could be extended?

John: The way the equipment is working now we really expect to be able to extend the mission. And extending the mission is very valuable because it will allow us to look for planets that have longer orbits than what we see with a three-and-a-half year mission; it lets us look for smaller planets – planets further from the stars – so as long as the vehicle is working properly and has the ability to communicate with the telecom system and has enough fuel left to keep it pointed correctly, we can extend the mission out and really continue the Kepler legacy. So we are looking forward to an extended mission after the primary mission is complete.

Roz: So now its summertime in Boulder, Colorado – what do you tell your neighbors over the backyard fence when they ask you, “Hey – what’s that Kepler discovering this week?”

John: You know the thing about Kepler is that it’s up there every day. It’s up there on Christmas, it’s up there on New Years, and it’s up there on the 4th of July. And every day it’s up there we get closer to finding that Earth-sized planet in the habitable zone so I tell them to hang in there – to keep patiently waiting for us to release the data but I think we are going to find a planet in the habitable zone before this is over.

Roz: So, keep the faith.

John: Absolutely.

Roz: Thanks, John.

End of podcast:

365 Days of Astronomy
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  1. October 2nd: Encore: Kepler Keeps on Giving - October 2, 2011

    […] This podcast originally aired on August 12th, 2010. […]

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