Kepler Channel Noise Problem

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Re: Kepler Channel Noise Problem

Post by Sirius_Alpha on 3rd November 2009, 12:59 pm

(some parts of this post have been removed as I calmed down a bit after writing it )
Alright, let's break it down.

15% of the data may have noise in it, and in that 15% of the data, only 25% of it is noisier than usual. That means that 3.57% of the total data will be noisier than usual. Since it was made clear that the noisy data can be flagged out, or corrected, that means that while that data won't help the hunt for exo-Earths, it won't hinder it either.

Why is everyone assuming that all the exo-Earths occupy that 15% of the data? Is Kepler that cursed? Those who know me well enough on this forum (and elsewhere) know that I'm a chronic pessimist, and yet even I think that we're still good to go.

TheoA, three years of the mission have not been lost, just 15% of the data from those three years, at most. Not all of the target stars have this noise issue. Remember HAT-P-7 b's secondary light curve and the "We have the ability to detect exo-Earths" press release? With the issue known before launch, it's obvious that not all target stars are affected from this data. If HAT-P-7 b is in the other 85% of the data, then why can't some exo-Earths? Is there something I'm not seeing here? Some reason why the other 85% (at least) of the data that will be unusable?

Edit (upon re-reading):

How sure are you that 100% of the stars will be affected by the 3 channels? Do all the photons from each star pass through each channel? (edit again:) And how does this fit in with the detection of the HAT-P-7 b secondary transit, which was of similar depth to an Earth-radius planet?

edit again...
Recall from the power-point presented earlier.
All 84 channels are operating & producing useful data
Photometric precision is about 1.5 times design values

Note it doesn't say that the 84 channels are functioning perfectly, but rather, are producing useful data. Is there some reason to doubt this? Even with 15% of the data noisier than usual, with a photometric precision of 1.5 times the design value, wouldn't this help alleviate the worry?

Someone on UMSF posted this image.

It suggests that channels are used for specific areas of the sky, instead of each channel processing all the data.

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Re: Kepler Channel Noise Problem

Post by TheoA on 3rd November 2009, 1:27 pm

Sirius,

You might have to read the Russian article again to see why all the data is being degraded.

There is nothing wrong with the photometers.

The problem is with the amplifiers. The article says that the signal is amplified 100 times and then de-amplified 100 times to remove noise. Kinda like Dolby processing.

This process has to be perfect as the next step is to compare the stars to each other and transmit the signal differences alone back to Earth. Can\'t stress this enough. The Signal itself is never sent back.

So the data from each photometer is compared with the others and the differences are transmitted back.

So if 3 amplifiers pump an anomalous 3% change into the matrix, any signal of less than roughly 1/8000 will simply not exist. There will be nothing sent back.

Also apparently this anomalous signal varies as well. So the only way to deal with it is to strike a line at say 1/5000 and drop everything below that. Simply too degraded to use.

This is what Borucki means when he says NO Earths in the habitable zone can be detect before the fix. Not just in that 15%, but in all 100%. We need a 1/10,000 signal to detect Earth. So there is an outside chance the dimmer stars might allow detection. But you see where I\'m going. All spin.

Remember Kepler was originally designed as a 1/100,000 machine. While COROT was a 1/10,000 machine.

Now the article could be wrong, but nothing Borucki says contradicts it.

As far as the HAT-P-7 b data, that was taken from the calibration data only and apparently used a manual over ride. More spin.


Last edited by TheoA on 4th November 2009, 6:54 pm; edited 2 times in total

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Re: Kepler Channel Noise Problem

Post by Borislav on 3rd November 2009, 1:32 pm

http://kepler.nasa.gov/sci/basis/diffphot.html
The key factors used to achieve the required differential performance for the Kepler Mission are:

Differential spatial photometry: The brightness of each target star is normalized to the average of all nearby stars, providing common-mode rejection in the measuring system.

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Re: Kepler Channel Noise Problem

Post by Sirius_Alpha on 3rd November 2009, 1:34 pm

Alright, that makes sense. But I am still curious as to how they pulled off measuring that HAT-P-7 b secondary transit then?

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Re: Kepler Channel Noise Problem

Post by Borislav on 3rd November 2009, 1:40 pm

Sirius_Alpha wrote:Alright, that makes sense. But I am still curious as to how they pulled off measuring that HAT-P-7 b secondary transit then?

http://infox.ru/science/universe/2009/11/02/NoisyCCDamplifiersdelayKeplerplanetsearch.phtml



Как признают создатели аппарата, о проблемах в нескольких усилителях было известно еще до запуска космического аппарата. «Все об этом знали, и все беспокоились», – признался Nature специалист по научному оборудованию Kepler Даг Калдуэлл. Во время летных испытаний даже удалось поймать фазовый эффект от одной известной экзопланеты: поскольку время и место появления эффекта были известны, можно было обойтись без дифференциальной фотометрии.


They write, during the calibration period (early May) mode differential photometry was not used.

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Re: Kepler Channel Noise Problem

Post by Sirius_Alpha on 3rd November 2009, 1:44 pm

Ah, thanks, Borislav. I don't suppose they could apply this to the rest of the Kepler target stars at once and still get back the hordes of data that was expected.

That leaves me with a final question before I'm satisfied (and upset v_v), what about the graphic showing the labels of the channels in the Kepler field? It seems to suggest that each channel gets used on only one section of the star field of view.


Last edited by Sirius_Alpha on 3rd November 2009, 1:52 pm; edited 2 times in total (Reason for editing : I need to sleep ...)

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Re: Kepler Channel Noise Problem

Post by TheoA on 3rd November 2009, 1:45 pm

Thanx Borislav.

Also note that during the calibration period only a tiny fraction of stars were selected for data download.

Once in automatic mode its a Hot Jupiter machine.


Last edited by TheoA on 4th November 2009, 6:55 pm; edited 1 time in total

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Re: Kepler Channel Noise Problem

Post by Borislav on 3rd November 2009, 1:53 pm

Sirius_Alpha wrote:That leaves me with a final question before I'm satisfied (and upset v_v), what about the graphic showing the labels of the channels in the Kepler field? It seems to suggest that each channel gets used on only one section of the star.

I do not know. But if mens of the project speak of need of the alteration of the whole algorithm, that see problem global.

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Re: Kepler Channel Noise Problem

Post by TheoA on 3rd November 2009, 2:35 pm

If they knew how to fix it it would have been fixed by now.

I suspect they don't know how to flag or separate the data yet. Which is why the dates are so tentative.

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Re: Kepler Channel Noise Problem

Post by Borislav on 3rd November 2009, 2:51 pm

TheoA wrote:If they knew how to fix it it would have been fixed by now.

I suspect they don't know how to flag or separate the data yet. Which is why the dates are so tentative.

Possible tests of new software already go

http://kepler.nasa.gov/about/manager.html
2009 October 14. Mission Manager Update

Last week, the team performed two semi-weekly spacecraft contacts. This “engineering” contact utilizes the vehicle’s X-Band transmitter and the omni-directional antennas to give us a relatively low bandwidth connection (typically ranging from 2 to 8 kbps). Although insufficient to downlink the extensive science data being collected and stored onboard, this connection has the benefit that we do not have to leave the science attitude and hence can continue to collect science data as the operations team checks out the vehicle. These contacts typically last about 8 hours, during which time onboard logs are downlinked, along with a small portion of the science targets that have been chosen to give us a quick look at the instrument performance in case any adjustments need to be made. These contacts also give us the opportunity to upload new command sequences, software patches or parameter updates, if required.

Afterwards passed two weeks, but reports on successful issue scientific given no Oct. 17-19, 2009.
Oh, I remember well waiting for this news to note that Kepler COROT overtaken by duration of continuous observation, but now there is no joy ...

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Re: Kepler Channel Noise Problem

Post by TheoA on 3rd November 2009, 2:57 pm

Borislav,

Those tests were to check the logs on the RAD750 safe mode issue. Not the algorithm.

While the patch may potentially be done in-flight, they should not do that as it will affect the integrity of the data being collected.

Ideally they should do it at a quarterly roll so they start from scratch.

As I read the internet blogs, its pretty clear everyone is completely confused as the Kepler team is deliberately trying to obscure the problem.

Its been a long time since I've seen a science team do this. Very disappointing.

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Re: Kepler Channel Noise Problem

Post by Sirius_Alpha on 3rd November 2009, 2:58 pm

Alright, I concede. I seem to have been mistaken about the whole thing.

Very disappointed now. Lazarus? Can you save me?

In the mean time, surely the Kepler team can get some energy drinks and pizza and stay up all night writing code. I've done it plenty of times.

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Re: Kepler Channel Noise Problem

Post by TheoA on 3rd November 2009, 3:12 pm

I'm still of the opinion they do not know how to fix this.

I know a couple of guys who worked on the rover missions and no one on this planet can pull the all nighter's they do.

I repeat, if they knew how to fix it, it would be fixed by now.


Last edited by TheoA on 4th November 2009, 6:55 pm; edited 1 time in total

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Re: Kepler Channel Noise Problem

Post by Sirius_Alpha on 3rd November 2009, 3:17 pm

I would think accusing the Kepler team of fraud is going too far. Even if Jupiters or the occasional Neptune are all Kepler uncovers, that will still indeed tell us valuable information about the efficiency of giant planet formation around a variety of stars. I am sure good science will come from Kepler, even if it isn't the science we all wanted. They say they can get it fixed later.

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Re: Kepler Channel Noise Problem

Post by TheoA on 3rd November 2009, 3:22 pm

Yes, much good science will come.

Except for Priorities 1,2 &,3 for the mission, we should be good.

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Re: Kepler Channel Noise Problem

Post by Sirius_Alpha on 3rd November 2009, 3:25 pm

TheoA wrote:Except for Priorities 1,2 &,3 for the mission, we should be good.
Great, going to be waking up every night crying because of this. Kepler broke, CoRoT broke, TPF and SIM are financially broke, and Darwin is on the chopping block.

I guess it [will] pays to be a radial-velocity user these days [even in the coming years].


Last edited by Sirius_Alpha on 3rd November 2009, 3:32 pm; edited 1 time in total (Reason for editing : Changed tense.)

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Re: Kepler Channel Noise Problem

Post by Borislav on 3rd November 2009, 3:31 pm

Sirius_Alpha wrote:
TheoA wrote:Except for Priorities 1,2 &,3 for the mission, we should be good.
Great, going to be waken up every night crying because of this. Kepler broke, CoRoT broke, TPF and SIM are financially broke, and Darwin is on the chopping block.

I guess it pays to be a radial-velocity user these days.

TESS is cancelled.

I hope that the team Kepler still give more information about the scale problem.

If problem really spreads on practically all data, that it is necessary to stop the collection scientific data and immediately go to test operation of the new algorithm. More so that fuel on board for correcting not infinitely.

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Re: Kepler Channel Noise Problem

Post by TheoA on 3rd November 2009, 3:55 pm

Borislav,

I agree.

looks like they are going to shovel a ton of Jupiters down our throats.

And then any Earth type detections will be attempted.

Actually that is a misnomer. Right now the performance is degraded
enough that there very well could be no rocky planets in this survey.

Thinking some more, if they shut it down right now one other solution might occur to them.

Right now the 4 corner modules are used for star tracking. So obviously
they have a way to shut down modules and retask them. They should pick
these 3 modules and permanently retask them.

This would save much of the mission but would destroy the science value of the last 6 months of data
meaning the science team could not publish anything next year.

Hopefully they do the right thing.

Maybe we should put some pressure on them.


Last edited by TheoA on 4th November 2009, 6:56 pm; edited 1 time in total

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Re: Kepler Channel Noise Problem

Post by Lazarus on 3rd November 2009, 3:57 pm

You know rather than relying on various press releases and posting wild demands for severed heads, it might be worth contacting them directly. There are contact addresses on the Kepler website you know.

But hey, don't let me ruin the fun of accusing William Borucki and the Kepler team of fraud in an internet forum Smile


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Re: Kepler Channel Noise Problem

Post by Sirius_Alpha on 3rd November 2009, 4:03 pm

Pressure .... isn't that a bad thing when careful analysis is in call for? Even if they do shove hundreds of hot Jupiters down my throat, I will gladly digest them, surely they'll find intermediate and long-period Jovians too. What about finding Neptunes around K-type stars?

If they can't find earth-like planets in 1 yr orbits, what about earth-like planets in the HZ of mid K-type stars, orbital periods of a couple months or whatever. M dwarfs? While a 1 M_e planet at 1 AU around G star is sought, I would settle for a 2 M_e planet at 0.3 AU around a K star.

Edit: Lazarus's idea is valid. I'll contact them and see if I can get a response.

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Re: Kepler Channel Noise Problem

Post by Borislav on 3rd November 2009, 4:11 pm

necessary more information about the scale problem....

Now I would be happy at only half of the photometry of the plan (50 000 stars), the main thing that the accuracy was within 20 ppm as promised and began observing since Christmas

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Re: Kepler Channel Noise Problem

Post by TheoA on 3rd November 2009, 4:17 pm

Sirius,

The person to contact would be David Koch. He's the one in charge of the instrumentation. I'll try him as well.

I think the people on this forum will be happy with Jupiters, the general public not so much.

Most people are of the view that Kepler should produce 50-100 earth like planets. They have been force fed this by the media and the science team. What happens when they are told this is not so. They have an attention span of 5 minutes.

There is a reason that all those missions you mentioned are dead with no tears shed. It is exactly due to C@%P like this. Keep us involved or your else... is their attitude.

We wouldn't have to speculate and depend on these info leaks if the science team would take 10 minutes to clarify the situation properly. Something they have known about for months if not years. How come they never mentioned this in all the previous contacts forum members have had with them?

The public is willing to tolerate some spectacular failures if there is full disclosure.


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Re: Kepler Channel Noise Problem

Post by Sirius_Alpha on 3rd November 2009, 4:19 pm

Indeed, Mr. Koch is the one who I e-mailed. I hope he isn't too busy. And yeah, the public's view is worrying. They were promised Earths, from a variety of sources.

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Re: Kepler Channel Noise Problem

Post by TheoA on 3rd November 2009, 5:03 pm

Borislav,

Again agree.

Original design = 1.4x10 -5 = 14 parts per million.

Hubble = 6x10 -6 = 6 parts per million

present IMO = 120 parts per million.

Needed for Earth = 80 parts per million

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Re: Kepler Channel Noise Problem

Post by Sirius_Alpha on 3rd November 2009, 5:06 pm

So HST can detect a transiting Earth? I didn't expect that.

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