It seems like months and months go by between Kepler reports these days, doesn't it?
Well, some of you have seen the Kepler stories in the news a few weeks back as we released the announcement of five newly discovered planets. There are many more on the way, but this is what we could put together from the first six weeks of flight data and a couple dozen nights of ground-based observing to eliminate the false positives, determine the mass of the planets and the detailed properties of the stars.
And much of the sorting through the data had to be done manually because our data processing software isn't fully functional here at Ames; some of the software development had to be deferred. The good news is that we finished development of a major software upgrade in late November, so we should be able to make up for lost time in the coming months. After all, we don't have just 6 weeks of data here, but almost a full year!
If you haven't done so recently, check out the Kepler website at http://kepler.nasa.gov. It's been updated and is much improved. Also, the official Kepler blog at http://blogs.nasa.gov/cm/blog/kepler. We are trying to get more people to participate in the blog, you know, to give you a wider range of experiences. The first two entries are mine, but I'm trying to get someone who was at the AAS conference to write about what it was like when the Kepler results were announced. Of course, that blog will never have the real inside scoop I have here (wink, wink).
Recently, Scottie sent me an email and asked what an exoplanet was.
Well, an exoplanet is any planet around another star. All the stars we are looking at are relatively nearby. Within our galaxy, between about 1,000 and 3,000 light years away (our galaxy is something like 250,000 light years across). Why do we only look at relatively nearby stars? Simple. We need the photons. Stars that are too far away are simply too faint to be accurately measured.
And what else has been happening?
We finally passed our post-launch assessment review and a management transition. The Kepler Mission is now being managed by Ames Research Center rather than the Jet Propulsion Lab. We had another Safemode, but we're getting pretty good at recovering from these. Never the less, I really am looking forward to seeing these things go away. In the mean time, I should probably point out that, though we take these things seriously, going to Safemode does no damage to the spacecraft, nor does it in any way shorten the mission life. It merely means that something unexpected happened, serious or confusing enough that the onboard computer decided it would be best to go to a safe state and wait for help from those of us on the ground. Safemode is the safest state of the spacecraft. Now, Emergency Mode would be a whole other story!
On the plus side, the changes we made back in September seem to be working great and our pointing accuracy has been superb, with no more incidents of the unexpected drops into our coarse-point mode. I did tell you about that, didn't I? We're continuing to make minor tweaks in the spacecraft operation to improve performance or reduce risks, and looking forward to the day when we can't find any more improvements to make, all to make the data better with less noise.
In December, we changed some settings on a heater that was cycling on and off every few hours and was somehow showing up in the stellar brightness measurements (somehow it seems to be affecting focus very slightly). Hours is about the duration of a planetary transit, so we really don't want things changing on that time scale. On the other hand, the heater is cycling to keep the reaction wheels warm, and we count on these wheels to keep us pointed accurately. So what we did is narrow the temperature limits, and now the heater cycles every 12 minutes or so, and isn't such a bother.
We are also getting ready to make some changes to the software running on the spacecraft. Updating the software requires us to reboot the processor, something you don't want to do very often, because there's always the chance it won't come back on! But we've been saving up a few minor bug fixes, and now have a more important bug to fix. It sent us into Safemode in November, and as long as we're going to fix that one, we're going to do the others, too. But we'll do a lot of testing first, and we'll make the update in April, during one of our regularly scheduled data downloads.
Otherwise, things are going rather well, so I don't have a lot to write about. Not that that seems to have inhibited me much.
Actually, there was a new development in January that had us hopping. In fact, it's delayed this update while we worked on it. It seems that one of our detector modules died.
Hopefully it's only dead, not dead dead, and maybe we can revive it. But it doesn't look good. This is the most serious issue we've had since we started gathering science data.
One of our modules (Module 3, on the edge of our field of view) stopped working on January 9. Since then it's been dark, with no star images.
The Kepler focal plane is approximately one foot square. It's composed of 25 individually mounted modules. The 4 corner modules are used for fine guiding and the other 21 modules are used for science observing. Attached are some pictures that show a single science module and the assembled focal plane with all 25 modules installed. Note that the fine guidance modules in the corners of the focal plane are very much smaller CCDs than the science modules. On the left, a single science module with two CCDs and a single field flattening lens mounted onto an Invar carrier. On the right, a focal plane assembly with all 21 science modules and four fine-guidance sensors, one in each corner, installed.
Under normal operations, each module and its electronics convert light into digital numbers. For the darkest parts of the image between stars, we expect these numbers to be very small (but not zero). Correspondingly, for the brightest stars in the image, much larger numbers are expected creating an image of each observed star and its background neighborhood. The numbers we see coming out of failed module 3 are all very similar in size and considerably lower than the normal levels. These numbers produce an image that looks like the "snow" on a television that has very bad reception. There are no stars visible in these images.
There are several ways a module to go bad, such as a blown fuse, a shorted or broken wire, or the failure of individual parts. The Kepler detectors were fabricated to rigid standards and subjected to rigorous testing on the ground before launch. And the design contains several redundant features to prevent the failure of a module, but the space environment is unforgiving and failures do occur. The fact that this anomaly affects all four channels on one module will help determine the probable cause.
Depending upon what caused the module to stop working, we might be able to recover it, though the flexibility of the Kepler design is limited in this extent. Even if the module is recoverable, it will be several weeks before recovery actions are taken because we need to review the current performance and design to ensure that any recovery steps do no further damage to the focal plane or spacecraft. I mean, the last thing we want to do is lose more modules while we try to recover this one!
The module that has stopped working is on the periphery of the field of view. Since the Kepler spacecraft rotates by 90 degrees every three months, this module would normally observe a different portion of the Kepler field of view each season, as shown in the following image. Hence, no part of the Kepler field of view has been rendered unobservable it's just that four regions are only observable three out of four seasons, or 75% of the time, if the module is unrecoverable.
 Kepler field of view showing position of the failed module for each season.
We specifically designed Kepler to preclude the propagation of failures such as this. The design is highly compartmentalized so that a failure in one area will not spread to another. There will be minor changes to the signals from the remaining science modules because the focal plane and its electronics have changed temperature somewhat since the bad module isn't drawing as much current anymore, but the current problem is not expected to spread beyond the one affected module.
As far as the affect on science goes, a rule of thumb would be that because only one of the 21 science modules is affected, that the reduction in science results will be about 5%. This shouldn't significantly affect the Kepler science performance.
So there you go. There's the latest, with an inside scoop.
Charlie Sobeck, Deputy Project Manager
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On the left, a single science module with two CCDs and a single field flattening lens mounted onto an Invar carrier. On the right, a focal plane assembly with all 21 science modules and four fine-guidance sensors, one in each corner, installed.
thank you for the detailed update, keep them coming you have a devoted public!!!
I have been taking a keen interest in this project for the past year and looking forward to the results over the next few years.
Its hard to overstate its importance.
It may take time to sink in but if the results show just how common planetary systems comparable to our own are, there will be little room for doubt that we cannot be alone.
Good to read some more info on the Kepler mission. I actually made this page my home when i start up my browser every morning. I always quickly check the "planet count". I have the feeling i am not the only one doing this. I really want to see that number jump to 3 digits very quickly!
one suggestion to your team (if you ever get bored ;-) ) you could make a 3d map and locate the so far found planets in there. Many people would be more fascinated if the see more than just tables with numbers. Especially kids. there should be a 3D map where you can place the 400 something exoplanets and then click them to display details. Much more fascinating than a list of pure data...
pressing my thumbs you will find some nice 22 degrees room temperature planets somewhere
Any chance of some news on when we might get to see some more data? I guess I am one of many people "hungry" for more info.
Regards
Just curious - You mentioned you had 12 months worth of data, it takes 3 transits to confirm a planet, so I would think planets can now be confirmed that have orbital periods as long as 4 months. This exceeds the orbital period of our own solar system planet Mercury.
So far the Kepler Science team have announced 5 planets with orbital periods of only a few days. Can you tell us how many leads you have for orbital periods of up to 4 months (understanding they will need to be confirmed by ground based telescopes)? Do you know when there will be another announcement?
Thanks!
Joe
The date on this blog post is Feb. 18, but it did not become publicly visible until about a month later. At least it did not appear for me and I have been checking this page frequently.
Just FYI, for those anxiously awaiting more data: "Telescope team may be allowed to sit on exoplanet data" (NASA panel agrees to Kepler team request to withhold key observations.) from the nature.com website, in NEWS for April 14 2010. See the article for details.
I am little disappointed, in 1 year of watching 100.000 stars you only found 5 planets witch have 4day orbit time, so this 5 planets took 4day x 4 transit times = 16 days( time to discover), when will be the next discoveries announced ?
Good luck !
Thank you for the informative post, I look forward to reading more in the future.
David Zilar
Thank-you for the information. I am very interested in any information you have on kepler!!! I appreciate your time in posting this. Looking forward to new information and new pictures from Kepler this april 2010. Hope it will show many more planets and hopefully an earth like one. In the meantime we need to take care of our earth in the event we finally find new life forms!!!
Greetings from Brazil!
Thank you very much for this update. Kepler is my favorite mission and as I am not really a patient guy, I was getting frustrated with all this time without information. I got many friends in my country who are also very interested on Kepler's mission. Despite the bad news about the module, I am pretty sure that this mission is going to change people's mind around the world.
Please, keep us updated!
Sad that Kepler is not completely perfect. But as said, little effect. I found one that is equal to the beautiful planet Earth, with beautiful beaches, mountains, rivers and some tasty fruit for us to do a juice. God forbid!
I believe that the investigation of regions similar to the Earth (edges of the Milky Way, where there is less "turbulence" gravitational) may harbor habitable planets around other stars. Good luck to the team of Kepler, is a good luck to us all!
Thank you for this information, even though I discovered it more than a month after you posted it. It is wonderful to get a bit of info about this amazing mission, and you seem to be one of very few who realize there are interested people "out there".
Among my friends interested in astronomy there is surprise about how little information has been revealed about Kepler. As you say there is almost a years worth of data, and only about the first six weeks has been confirmed and reported. Obviously, to confirm the data takes time, and the field has been in a bad place for most of the ground based instruments during the winter. But there should be lots of people looking at preliminary data at least in a statistical way.
To think that the interested public can't handle thoughts and results that are given as preliminary possibilities is to underestimate their intelligence( I realize this may not be true for the media) Anyway, this is an incredible time of learning for mankind, and bureaucracy always has a tendency to withhold. The current policy could make it 8 to 10 years before the results of interest get discussed, although, I'm sure it won't be that bad.
At any rate thank you for the info, and you are not in anyway responsible for my rant. I even sense you have some frustration with the lack of communication. I look forward to any new posts..
Thank you for this information, even though I discovered it more than a month after you posted it. It is wonderful to get a bit of info about this amazing mission, and you seem to be one of very few who realize there are interested people "out there".
Among my friends interested in astronomy there is surprise about how little information has been revealed about Kepler. As you say there is almost a years worth of data, and only about the first six weeks has been confirmed and reported. Obviously, to confirm the data takes time, and the field has been in a bad place for most of the ground based instruments during the winter. But there should be lots of people looking at preliminary data at least in a statistical way.
To think that the interested public can't handle thoughts and results that are given as preliminary possibilities is to underestimate their intelligence( I realize this may not be true for the media) Anyway, this is an incredible time of learning for mankind, and bureaucracy always has a tendency to withhold. The current policy could make it 8 to 10 years before the results of interest get discussed, although, I'm sure it won't be that bad.
At any rate thank you for the info, and you are not in anyway responsible for my rant. I even sense you have some frustration with the lack of communication. I look forward to any new posts..
Thank you very much for the update! Do we have an expectation of when the next report of results will be available and how many targets are being worked by the follow-up groups currently?
Thanks.
This is an awesome post. I like how you went into detail about the spacecraft. Can't wait to hear more about the mission.
Charlie , thanks for the update . Keep up the good work . As long as we learn better ways to look after this planet it will be worth it .
Best regards ,
Dave
Aw, it's so sad that one of your modules died. I hope you guys will fix it. Kepler is my favorite mission.
Good luck with the module and the rest of the data collection and analysis.