Kepler

[stephen63]

Earth as seen from a nearby civilization's version of Kepler.

Yep, it's inhabited

[bystander]

Gravity-Bending Find Leads to Kepler Meeting Einstein
NASA | JPL-Caltech | 2013 Apr 04

[i]This artist's concept depicts a dense, dead star called a white dwarf crossing in front of a small, red star. The white dwarf's gravity is so great it bends and magnifies light from the red star. [b](Credit: NASA/JPL-Caltech)[/b][/i]

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[i]This chart shows data from NASA's Kepler space telescope, which looks for planets by monitoring changes in the brightness of stars. As planets orbit in front of a star, they block the starlight, causing periodic dips. The plot on the left shows data collected by Kepler for a star called KOI-256, which is a small red dwarf. At first, astronomers thought the dip in starlight was due to a large planet passing in front of the star. But certain clues, such as the sharpness of the dip, indicated it was actually a white dwarf -- the dense, heavy remains of a star that was once like our sun. In fact, in the data shown at left, the white dwarf is passing behind the red dwarf, an event referred to as a secondary eclipse. The change in brightness is a result of the total light of the system dropping. [b](Credit: NASA/Ames/JPL-Caltech)[/b][/i]

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Click to play embedded YouTube video.

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NASA's Kepler space telescope has witnessed the effects of a dead star bending the light of its companion star. The findings are among the first detections of this phenomenon -- a result of Einstein's theory of general relativity -- in binary, or double, star systems.

The dead star, called a white dwarf, is the burnt-out core of what used to be a star like our sun. It is locked in an orbiting dance with its partner, a small "red dwarf" star. While the tiny white dwarf is physically smaller than the red dwarf, it is more massive.

"This white dwarf is about the size of Earth but has the mass of the sun," said Phil Muirhead of the California Institute of Technology, Pasadena, lead author of the findings to be published April 20 in the Astrophysical Journal. "It's so hefty that the red dwarf, though larger in physical size, is circling around the white dwarf."

Kepler's primary job is to scan stars in search of orbiting planets. As the planets pass by, they block the starlight by miniscule amounts, which Kepler's sensitive detectors can see.

"The technique is equivalent to spotting a flea on a light bulb 3,000 miles away, roughly the distance from Los Angeles to New York City," said Avi Shporer, co-author of the study, also of Caltech.

Muirhead and his colleagues regularly use public Kepler data to search for and confirm planets around smaller stars, the red dwarfs, also known as M dwarfs. These stars are cooler and redder than our yellow sun. When the team first looked at the Kepler data for a target called KOI-256, they thought they were looking at a huge gas giant planet eclipsing the red dwarf.

"We saw what appeared to be huge dips in the light from the star, and suspected it was from a giant planet, roughly the size of Jupiter, passing in front," said Muirhead.

To learn more about the star system, Muirhead and his colleagues turned to the Hale Telescope at Palomar Observatory near San Diego. Using a technique called radial velocity, they discovered that the red dwarf was wobbling around like a spinning top. The wobble was far too big to be caused by the tug of a planet. That is when they knew they were looking at a massive white dwarf passing behind the red dwarf, rather than a gas giant passing in front.

The team also incorporated ultraviolet measurements of KOI-256 taken by the Galaxy Evolution Explorer (GALEX), a NASA space telescope now operated by the California Institute of Technology in Pasadena. The GALEX observations, led by Cornell University, Ithaca, N.Y., are part of an ongoing program to measure ultraviolet activity in all the stars in Kepler field of view, an indicator of potential habitability for planets in the systems. These data revealed the red dwarf is very active, consistent with being "spun-up" by the orbit of the more massive white dwarf.

The astronomers then went back to the Kepler data and were surprised by what they saw. When the white dwarf passed in front of its star, its gravity caused the starlight to bend and brighten by measurable effects.

"Only Kepler could detect this tiny, tiny effect," said Doug Hudgins, the Kepler program scientist at NASA Headquarters, Washington. "But with this detection, we are witnessing Einstein's theory of general relativity at play in a far-flung star system."

One of the consequences of Einstein's theory of general relativity is that gravity bends light. Astronomers regularly observe this phenomenon, often called gravitational lensing, in our galaxy and beyond. For example, the light from a distant galaxy can be bent and magnified by matter in front of it. This reveals new information about dark matter and dark energy, two mysterious ingredients in our universe.

Gravitational lensing has also been used to discover new planets and hunt for free-floating planets.

In the new Kepler study, scientists used the gravitational lensing to determine the mass of the white dwarf. By combining this information with all the data they acquired, the scientists were also able to measure accurately the mass of the red dwarf and the physical sizes of both stars. Kepler's data and Einstein's theory of relativity have together led to a better understanding of how binary stars evolve.

Characterizing the Cool KOIs. V. KOI-256: A Mutually Eclipsing Post-common Envelope Binary - Philip S. Muirhead et al

• Astrophysical Journal 767(2) 111 (2013 Apr 20) DOI: 10.1088/0004-637X/767/2/111

[bystander]

Kepler Discovers its Smallest 'Habitable Zone' Planets to Date
NASA | Ames Research Center | Kepler | 2013 Apr 18

Relative sizes of Kepler habitable zone planets discovered as of 2013 April 18. Left to right: Kepler-22b, Kepler-69c, Kepler-62e, Kepler-62f, and Earth (except for Earth, these are artists' renditions). (Credit: NASA/Ames/JPL-Caltech)

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Kepler-62 and the Solar System - Credit: NASA/Ames/JPL-Caltech The diagram compares the planets of the inner solar system to Kepler-62, a five-planet system about 1,200 light-years from Earth.

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Kepler-69 and the Solar System - Credit: NASA/Ames/JPL-Caltech The diagram compares the planets of the inner solar system to Kepler-69, a two-planet system about 2,700 light-years from Earth.

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Click to play embedded YouTube video.

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NASA's Kepler mission has discovered two new planetary systems that include three super-Earth-size planets in the "habitable zone," the range of distance from a star where the surface temperature of an orbiting planet might be suitable for liquid water.

The Kepler-62 system has five planets; 62b, 62c, 62d, 62e and 62f. The Kepler-69 system has two planets; 69b and 69c. Kepler-62e, 62f and 69c are the super-Earth-sized planets.

Two of the newly discovered planets orbit a star smaller and cooler than the sun. Kepler-62f is only 40 percent larger than Earth, making it the exoplanet closest to the size of our planet known in the habitable zone of another star. Kepler-62f is likely to have a rocky composition. Kepler-62e, orbits on the inner edge of the habitable zone and is roughly 60 percent larger than Earth.

The third planet, Kepler-69c, is 70 percent larger than the size of Earth, and orbits in the habitable zone of a star similar to our sun. Astronomers are uncertain about the composition of Kepler-69c, but its orbit of 242 days around a sun-like star resembles that of our neighboring planet Venus.

Scientists do not know whether life could exist on the newfound planets, but their discovery signals we are another step closer to finding a world similar to Earth around a star like our sun.

"The Kepler spacecraft has certainly turned out to be a rock star of science," said John Grunsfeld, associate administrator of the Science Mission Directorate at NASA Headquarters in Washington. "The discovery of these rocky planets in the habitable zone brings us a bit closer to finding a place like home. It is only a matter of time before we know if the galaxy is home to a multitude of planets like Earth, or if we are a rarity."

The Kepler space telescope, which simultaneously and continuously measures the brightness of more than 150,000 stars, is NASA's first mission capable of detecting Earth-size planets around stars like our sun. Orbiting its star every 122 days, Kepler-62e was the first of these habitable zone planets identified. Kepler-62f, with an orbital period of 267 days, was later found by Eric Agol, associate professor of astronomy at the University of Washington and co-author of a paper on the discoveries published in the journal Science.

The size of Kepler-62f is now measured, but its mass and composition are not. However, based on previous studies of rocky exoplanets similar in size, scientists are able to estimate its mass by association.

"The detection and confirmation of planets is an enormously collaborative effort of talent and resources, and requires expertise from across the scientific community to produce these tremendous results," said William Borucki, Kepler science principal investigator at NASA's Ames Research Center at Moffett Field, Calif., and lead author of the Kepler-62 system paper in Science. "Kepler has brought a resurgence of astronomical discoveries and we are making excellent progress toward determining if planets like ours are the exception or the rule."

The two habitable zone worlds orbiting Kepler-62 have three companions in orbits closer to their star, two larger than the size of Earth and one about the size of Mars. Kepler-62b, Kepler-62c and Kepler-62d, orbit every five, 12, and 18 days, respectively, making them very hot and inhospitable for life as we know it.

The five planets of the Kepler-62 system orbit a star classified as a K2 dwarf, measuring just two-thirds the size of the sun and only one-fifth as bright. At seven billion years old, the star is somewhat older than the sun. It is about 1,200 light-years from Earth in the constellation Lyra.

A companion to Kepler-69c, known as Kepler-69b, is more than twice the size of Earth and whizzes around its star every 13 days. The Kepler-69 planets' host star belongs to the same class as our sun, called G-type. It is 93 percent the size of the sun and 80 percent as luminous and is located approximately 2,700 light-years from Earth in the constellation Cygnus.

"We only know of one star that hosts a planet with life, the sun. Finding a planet in the habitable zone around a star like our sun is a significant milestone toward finding truly Earth-like planets," said Thomas Barclay, Kepler scientist at the Bay Area Environmental Research Institute in Sonoma, Calif., and lead author of the Kepler-69 system discovery published in the Astrophysical Journal.

When a planet candidate transits, or passes in front of the star from the spacecraft's vantage point, a percentage of light from the star is blocked. The resulting dip in the brightness of the starlight reveals the transiting planet's size relative to its star. Using the transit method, Kepler has detected 2,740 candidates. Using various analysis techniques, ground telescopes and other space assets, 122 planets have been confirmed.

Early in the mission, the Kepler telescope primarily found large, gaseous giants in very close orbits of their stars. Known as "hot Jupiters," these are easier to detect due to their size and very short orbital periods. Earth would take three years to accomplish the three transits required to be accepted as a planet candidate. As Kepler continues to observe, transit signals of habitable zone planets the size of Earth orbiting stars like the sun will begin to emerge.

Kepler's Smallest Habitable Zone Planets
NASA | Ames Research Center | Kepler | 2013 Apr 18

New Earth-like planets found
Carnegie Institution for Science | 2013 Apr 18

Two Water Worlds for the Price of One
Harvard-Smithsonian Center for Astrophysics | 2013 Apr 18

The most exciting candidates for habitable exoplanets yet
Max Planck Institute for Astronomy | 2013 Apr 18

New Techniques Allow Discovery of Smallest Super-Earth Exoplanets
National Science Foundation | 2013 Apr 18

Kepler Team Finds System with Two Potentially Habitable Planets
Universe Today | Nancy Atkinson | 2013 Apr 18

Water Worlds in the Habitable Zone
Centauri Dreams | Paul Gilster | 2013 Apr 18

An Alien Solar System With Two Earth-Sized Worlds
Slate Blogs | Bad Astronomy | 2013 Apr 18

Kepler-62: A Star System With Two Earths?
Discovery News | Irene Klotz | 2013 Apr 18

Five-planet system with most Earthlike exoplanet yet
University of Washington | 2013 Apr 18

Notre Dame astrophysicist discovers planets similar to Earth
University of Notre Dame | 2013 Apr 18

Kepler Discovers Smallest 'Habitable Zone' Planets
NASA Science News | Dr. Tony Phillips | 2013 Apr 18

[MargaritaMc]

http://asterisk.apod.com/viewtopic.php?f=31&t=31206
M

[saturno2]

" New Earth-like planets found "
Earth-like planets in habitable orbit
Very very well
And the life? Where there is life?
Kepler mission is very important

[mjimih]

The Chance of Finding Aliens
http://www.skyandtelescope.com/resource ... 04541.html
Drake equation
N = R x fp x ne x fl x fi x fc x L
fp is the fraction of these stars that have solar systems of planets, BOOSTED!
ne is the avg number of "Earthlike" planets (potentially suitable for life) in the typical solar system BOOSTED!

Kepler has fine tuned the math profoundly for fp & ne, but new found optimism for finding
other "radio telescopes" out there, partially based on general SETI efforts' lack of finding anything so far, is not actually warranted yet. But now we can probably ask "Where the heck IS everybody?"

[stephen63]

The Chance of Finding Aliens
http://www.skyandtelescope.com/resource ... 04541.html
Drake equation
N = R x fp x ne x fl x fi x fc x L
fp is the fraction of these stars that have solar systems of planets, BOOSTED!
ne is the avg number of "Earthlike" planets (potentially suitable for life) in the typical solar system BOOSTED!

Kepler has fine tuned the math profoundly for fp & ne, but new found optimism for finding
other "radio telescopes" out there, partially based on general SETI efforts' lack of finding anything so far, is not actually warranted yet. But now we can probably ask "Where the heck IS everybody?"

http://www.coseti.org/paper_01.htm

[Ann]

Stephen, I'm very impressed with your processing of many Hubble pictures of galaxies. Very beautiful and fascinating!

As for Kepler, it has most definitely shown us that planets are extremely common. This is a fact that was not known before, so it is a truly groundbreaking discovery. I want to point out, however, that once we knew that large planets are common, then we had every reason to believe that Earth-sized planets are common, too. Why not? Why would they be uncommon? There are two of them in the Solar system, Earth and Venus. And there are two Jupiter-sized planets (although only one Jupiter-mass one) in our Solar system, and two Neptune-sized and Neptune-mass ones. There is also an extremely high number of small rocky bodies in our Solar system, from Mars, Mercury, Ganymede and Titan down to a bewildering array of moons, minor planets and asteroids.

Please note that we have known for a relatively long time that other stars have dust belts and dust halos comparable to the Kuiper Belt and the Oort Cloud. We have also known for a moderately long time that other stars have giants planets. If other planets have very large planets and lots of very small rocky planetoids, why shouldn't many of them also have Earth-sized planets? Why should it be hard to make planets the size of the Earth?

But the fact that planets are Earth-size doesn't automatically make them Earth-like. Suppose astronomers announced that they had found a perfectly Earth-size, almost perfectly Earth-mass planet in orbit around an extremely Sun-like sun, and the planetary orbit was a bit small but probably large enough that water could be liquid there. What's more, the planet had a detectable atmosphere. Wouldn't we be excited? But in fact, I just described planet Venus, which for all its similarities to the Earth is extremely Earth-unlike.

Would planet Venus have been a truly Earth-like world if it had been in planet Earth's orbit? Would it have had liquid water and abundant life, even if it was just abundant bacterial life? Until we can answer that, I don't really think we can talk about "Earth-like" planets.

Ann

[Chris Peterson]

Would planet Venus have been a truly Earth-like world if it had been in planet Earth's orbit? Would it have had liquid water and abundant life, even if it was just abundant bacterial life? Until we can answer that, I don't really think we can talk about "Earth-like" planets.

That's an interesting question, but not one we need to fully understand or be able to answer in order to investigate Earth-like planets in other systems. For that we need to be able first to detect planets structurally similar to Earth (which we seem to be getting quite good at), and then to be able to study their atmospheres, which we are just beginning to manage.

[stephen63]

Stephen, I'm very impressed with your processing of many Hubble pictures of galaxies. Very beautiful and fascinating!

As for Kepler, it has most definitely shown us that planets are extremely common. This is a fact that was not known before, so it is a truly groundbreaking discovery. I want to point out, however, that once we knew that large planets are common, then we had every reason to believe that Earth-sized planets are common, too. Why not? Why would they be uncommon? There are two of them in the Solar system, Earth and Venus. And there are two Jupiter-sized planets (although only one Jupiter-mass one) in our Solar system, and two Neptune-sized and Neptune-mass ones. There is also an extremely high number of small rocky bodies in our Solar system, from Mars, Mercury, Ganymede and Titan down to a bewildering array of moons, minor planets and asteroids.

Please note that we have known for a relatively long time that other stars have dust belts and dust halos comparable to the Kuiper Belt and the Oort Cloud. We have also known for a moderately long time that other stars have giants planets. If other planets have very large planets and lots of very small rocky planetoids, why shouldn't many of them also have Earth-sized planets? Why should it be hard to make planets the size of the Earth?

But the fact that planets are Earth-size doesn't automatically make them Earth-like. Suppose astronomers announced that they had found a perfectly Earth-size, almost perfectly Earth-mass planet in orbit around an extremely Sun-like sun, and the planetary orbit was a bit small but probably large enough that water could be liquid there. What's more, the planet had a detectable atmosphere. Wouldn't we be excited? But in fact, I just described planet Venus, which for all its similarities to the Earth is extremely Earth-unlike.

Would planet Venus have been a truly Earth-like world if it had been in planet Earth's orbit? Would it have had liquid water and abundant life, even if it was just abundant bacterial life? Until we can answer that, I don't really think we can talk about "Earth-like" planets.

Ann

Thank you for looking at my rendition of Hubble data and the kind words, Ann! However, I'm not sure where you got the impression that I had doubts as to the commonality of earth sized planets in the Milky Way or any other galaxy. I believe there must be a large number of them! But, I don't believe we will ever have a definitive answer if there is life on a a particular exoplanet. Telltale signs such as methane and oxygen in it's atmosphere is a good indicator, but what evidence would it take for you to be absolutely sure?

[Ann]

Stephen63 wrote:
Telltale signs such as methane and oxygen in it's atmosphere is a good indicator, but what evidence would it take for you to be absolutely sure?

If a planetary atmosphere other than the Earth's was shown to contain large amounts of O2, an unstable gas, as well as methane and water vapor, then I would be very impressed.

Ann

[bystander]

Has Kepler Found Ideal SETI-target Planets?

NASA Doubles Down on Exoplanets and the
SETI Institute Will Be Part of the Search

SETI Institute | 2013 Apr 19

Thoughts on Kepler 62 and Habitability
Centauri Dreams | Paul Gilster | 2013 Apr 22

How 'Habitable' Are Kepler's New Worlds?
Discovery News | Ray Villard | 2013 Apr 22

[bystander]

Detection of two new exoplanets with Kepler, SOPHIE and HARPS-N
Centro de Astrofísica da Universidade do Porto (CAUP) | EXOEarths | 2013 Apr 29

[img3="Artist's impression of a "hot Jupiter". Image: Ricardo Cardoso Reis (CAUP)"]http://www.astro.up.pt/divulgacao/nimag ... br29_1.jpg[/img3]

[i]The orbits of KOI-200b (left) and KOI-889b (right). Image: CNRS/Ricardo Cardoso Reis (CAUP)[/i]

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An international team of astronomers, including Alexandre Santerne of the EXOEarths team from CAUP, identified and characterized two new exoplanets, thanks to combined observations from the Kepler space telescope (NASA), plus SOPHIE and HARPS-N spectrographs.

These planets, named KOI-200 b and KOI-889 b are among the first detected with the new high-accuracy spectrograph HARPS-N, the northern hemisphere counterpart of the most prolific exoplanet hunter, HARPS (ESO). CAUP researcher Alexandre Santerne commented: "The SOPHIE spectrograph was already playing an important role in the characterization of Kepler planets by unveiling the true nature of the candidates and measuring the mass of giant planets. With the new HARPS-N spectrograph, with an even better accuracy, we expect to characterize much smaller exoplanets, hopefully down to the size of the Earth."

The new planets have about the size of Jupiter, but eccentric orbits with periods of less than 10 days. These new results help to further understand the evolution of orbits of these planets located very close to their star, known as "hot Jupiters".

There are currently more than 850 known exoplanets, but as seen from the Earth, only some of them are oriented in a way that they are passing in front of their star every orbital period. These periodic transits of the planet in front of its star produce a small dip in its brightness. These micro eclipses allow astronomers to know the diameter of the planet and some details about its atmosphere.

The Kepler space mission (NASA) has identified more than 2000 stars that have great chance of hosting transiting planets. However, most of them need complementary ground-based observations to establish their nature and to complete their characterization.

The team participated to these ground-based observations since 2010, using the SOPHIE instrument, which has already participated in the detection and characterization to more than fifteen Kepler planets, through the radial velocity method. Their observing program is now completed by new observations with the more accurate HARPS-N spectrograph.

KOI-200 b is slightly bigger than Jupiter and slightly less massive. With a low density, this gaseous planet is orbiting around its star in less than one week. The planet KOI-889 b is of the size of Jupiter but is ten times more massive. This very-massive planet is orbiting around its star in slightly less than 9 days. These two planets have eccentric orbits: during their orbit, their distance to their star is varying. This produces large variation in their equilibrium temperature of several hundred of degrees in a few days.

KOI-889 b, which is among the most massive planets discovered so far, is also among the most eccentric transiting planets. It could have been formed by a different mechanism than less massive planets. Santerne added: "Even if there are just hot and giant planets as we already know hundreds of them, these two planets are orbiting on a highly eccentric orbit, which is relatively rare for such short-period planets. I prefer to see these two new planets as two other bricks in the wall of our knowledge about planetary systems: bigger is the wall, better we understand planetary formation and evolution."

KOI-200b and KOI-889b: two transiting exoplanets detected and characterized with Kepler, SOPHIE and HARPS-N - G. Hebrard et al

• arXiv.org > astro-ph > arXiv:1304.6002 > 22 Apr 2013

[bystander]

03 May 2013 issue of Science is bursting with exoplanets

Science, 03 May 2013, Vol 340, Issue 6132, Pages 517-652

Kepler’s Tally of Planets - New York Times - 23 Apr 2013

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Exoplanets Explained (2013 May 14)

Click to play embedded YouTube video.

[mjimih]

1968 clip of Stanley Kubrick. I love this clip of the future, from the past.

Click to play embedded YouTube video.

Mark

[bystander]

Malfunction Could Mark the End of NASA's Kepler Mission
ScienceInsider | Yudhijit Bhattacharjee | 2013 May 15

One of the most successful missions in NASA history may be coming to an end. NASA officials announced this afternoon that the Kepler spacecraft, which has found more than 2700 planetary candidates outside the solar system, has lost the ability to point in a specified direction due to the malfunctioning of one of its reaction wheels. The spacecraft has been put into safe mode while engineers attempt to figure out how to resolve the malfunction.

Launched in 2009, the Kepler mission completed its 3.5-year planned run last year, winning plaudits from planetary scientists. The spacecraft monitors some 150,000 sunlike stars in search of transiting planets. In November 2012, the mission began an extension of an additional 3.5 years, and officials were hopeful that it would continue beaming back data until 2016.

That now looks uncertain following the failure of the second of its four reaction wheels, officials announced at a telecom this afternoon. One of the wheels failed last year, and the spacecraft needs three reaction wheels to be pointed precisely. Mission managers learned of the latest failure earlier this week.

Engineers must either regain functionality of one of the two broken wheels or find another way of pointing the spacecraft as desired. "We are not down and out," says Charles Sobeck, deputy project manager for Kepler at NASA's Ames Research Center in Moffett Field, California. "The spacecraft is safe and stable. We'll proceed with our investigation."

Sobeck says that "the mission itself has been spectacularly successful. We have lots of data on the ground still to pore through. The next question is going to be what the future of the mission looks like."

Kepler Update: Thruster-Controlled Safe Mode
NASA | Ames Research Center | Kepler | 2013 May 15

Kepler Mission Down But Not Yet Out
NASA | Astrobiology Magazine | 2013 May 15

Kepler Planet-Finding Mission in Jeopardy
Slate Blogs | Bad Astronomy | 2013 May 15

Kepler Planet-Hunting Mission in Jeopardy
Universe Today | Nancy Atkinson | 2013 May 15

Kepler's Planet-Hunting Mission May Be Over
Discovery News | Irene Klotz | 2013 May 15

[BDanielMayfield]

Kepler takes a long time to get data on planets with slower orbits right? Kepler would have seen Earth only 3 or 4 times by now. Planets like our little Earth are in a somewhat harder location in a solar system for an instrument like Kepler to see as often for the first years of it's mission right, taking at least a year to go around their star just once. Seems to me Kepler would have been designed for the long haul seeing as it has to wait for farther out planets to get around their stars a few more times, to help it discern their masses more precisely. Maybe three sets of three gyros, each with one back up, maybe next time. That would last it 30 years at least.

Sounds good for the next mission. Another thing that makes detection of earthlike planets in earthlike orbits harder is gaps in the data, i.e. when Kepler would have to stop data collection to download it back to earth, which happened every three months. Planets with orbits close to ours could have been missed due to the signal being in phase with the periods of downtime. Unscheduled downtime periods would likely have also caused some planets to be missed too. The next Kepler like mission should be configured to minimize or illiminate the need to stop data collection if at all possible.

Mark, I’ve enjoyed your comments in this thread, for example your description of this process as Kepler’s “succumbing to entropy”. I quoted this phrase in a posting I made on Sky and Telescope's newsblog on a Kelly Beaty article about Kelper's latest and perhaps its final, terminal failure:

http://www.skyandtelescope.com/news/Kep ... 49481.html

[neufer]

Kepler takes a long time to get data on planets with slower orbits right? Kepler would have seen Earth only 3 or 4 times by now. Planets like our little Earth are in a somewhat harder location in a solar system for an instrument like Kepler to see as often for the first years of it's mission right, taking at least a year to go around their star just once.

This problem is compounded by the fact that since the Sun is only 30' minutes wide as seen from Earth the chance of an Earth transit being seen from some random spot in deep space is only ~1 in 230 (= 30' in radians / 2).

[mjimih]

BDanielMayfield;
So today’s (Jan 27, 2013) the day when they try turning Kepler’s squeaky gyro-wheel back on. The newscientist article Mark linked to gave the impression that the Kepler people weren’t all that tense about this, but with no remaining backups … What a bummer if this is it for Kepler. I know it’s like Monday morning quarterbacking, but it seems strange in hindsight that they sent it up with only one extra control wheel. Doesn’t Hubble have several extra gyros?

unfortunately you are right so far. There is still hope though, ...but how about that Vikings NFL team, do you think they could win the Super Bowl this year? They've been there 4 times and haven't won it yet. talk about a bummer!

Mark

[bystander]

How NASA Might Revive the Kepler Space Telescope
Stanford University | 2013 May 15

Scott Hubbard, a consulting professor of aeronautics and astronautics, helped guide the Kepler mission when he served as director of NASA Ames Research Center. He explains how NASA might bring the planet-hunting spacecraft back online.
...

• How might NASA engineers go about getting Kepler functional again?
  
  There are two possible ways to salvage the spacecraft that I'm aware of. One is that they could try turning back on the reaction wheel that they shut off a year ago. It was putting metal on metal, and the friction was interfering with its operation, so you could see if the lubricant that is in there, having sat quietly, has redistributed itself, and maybe it will work.
  
  The other scheme, and this has never been tried, involves using thrusters and the solar pressure exerted on the solar panels to try and act as a third reaction wheel and provide additional pointing stability. I haven't investigated it, but my impression is that it would require sending a lot more operational commands to the spacecraft.

...

[mjimih]

My first thought was to aim Kepler somewhere else, like in a near opposite direction. Turn on the gyros and see if the new orientation makes the gyros work on "fresh" areas of their parts in some way. maybe the oil lube would cover other areas. Start over, looking elsewhere.

[BDanielMayfield]

BDanielMayfield;
So today’s (Jan 27, 2013) the day when they try turning Kepler’s squeaky gyro-wheel back on. The newscientist article Mark linked to gave the impression that the Kepler people weren’t all that tense about this, but with no remaining backups … What a bummer if this is it for Kepler. I know it’s like Monday morning quarterbacking, but it seems strange in hindsight that they sent it up with only one extra control wheel. Doesn’t Hubble have several extra gyros?

unfortunately you are right so far. There is still hope though, ...but how about that Vikings NFL team, do you think they could win the Super Bowl this year? They've been there 4 times and haven't won it yet. talk about a bummer!

Mark

Well, at least they were able to get a few more months of data. Yes hope lingers on, but it seems that it now hinges on the first squeaky wheel's being able to have greased itself in zero g. How likely is that?

As to your other cause for bummed out-ness, since I live far to your south my hopes are usually dashed in December in recent years. But the Vikings could face the Texans, and then only one of us would get bummed!

[Chris Peterson]

My first thought was to aim Kepler somewhere else, like in a near opposite direction. Turn on the gyros and see if the new orientation makes the gyros work on "fresh" areas of their parts in some way. maybe the oil lube would cover other areas. Start over, looking elsewhere.

They aren't gyros, but reaction wheels. They have much lower mass than the entire spacecraft, and move the spacecraft's orientation by spinning continuously for an extended period. They have no "fresh" areas on their bearings. One of the procedures used to try and extend the life of the wheel was to spin it up, both to distribute lubrication and to polish down any rough spot.

[mjimih]

so it doesn't matter where the craft is pointing, the wheels function exactly the same. *sigh*

[bystander]

Kepler Mission Manager Update
NASA | Ames Research Center | Kepler | 2013 May 21

Following the apparent failure of reaction wheel 4 on May 11, 2013, engineers were successful at transitioning the spacecraft from a Thruster-Controlled Safe Mode to Point Rest State at approximately 3:30 p.m. PDT on Wednesday, May 15, 2013. The spacecraft has remained safe and stable in this attitude and is no longer considered to be in a critical situation.

As part of a normal spacecraft response to a pointing error, redundant electronics were automatically powered off to isolate them as a possible cause. However, once the team recovered the spacecraft to Point Rest State (PRS) and exonerated those systems, they were turned back on, providing full redundancy to the spacecraft. The reaction wheels remain offline. The photometer, which was turned off to reduce the power load, will be turned back on in the near future to keep thermal conditions of the spacecraft within nominal operating parameters. Kepler is not in science data collection.

PRS was developed in order to preserve fuel for an eventual recovery effort once a second wheel failed. This state uses thrusters to control the pointing of the spacecraft, tipping it towards the sun and letting the solar pressure tip it back away, resembling the motion of a pendulum. This is a very fuel-efficient mode, and it also provides an on-demand telemetry link to allow engineers to monitor and command the spacecraft. With nearly a week of PRS operations, the fuel usage appears to be on the low end of our estimates, allowing time for recovery planning.

The operations staff at Ball Aerospace did a wonderful job at developing and implementing PRS. As a result, the spacecraft is not in an emergency condition, and work can be conducted at a more deliberate pace. For the next week or so, we will contact the spacecraft on a daily basis to ensure PRS continues to operate as expected.

Over the coming weeks, an anomaly response team (ART) will evaluate wheel recovery options. The ART includes members from NASA Ames, Ball Aerospace, the Jet Propulsion Laboratory and UTC, the wheel manufacturer. This team has access to a broader reach of experts throughout NASA and industry, and will manage the wheel recovery efforts.

The team will continue to analyze recent telemetry received from the spacecraft. This analysis, and any planned recovery actions, will take time, and will likely be on the order of weeks, possibly months. Any planned commanding will first be vetted on the spacecraft test bed to validate command operability.

For now, PRS is working very well and keeping Kepler safe. We will provide updates on significant changes as the plan develops.