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3 out of 4 SOHO Extreme ultraviolet Imaging Telescopes in BakeOut!

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posted on May, 2 2010 @ 07:23 AM
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lol.. WOW, 3 of SOHO's 4 Extreme ultraviolet Imaging Telescopes - EIT 171, EIT 284, and EIT 304, are currently in Bakeout mode!



'Bakeout' is a procedure where the Extreme ultraviolet Imaging Telescope (EIT) on board SOHO is taken offline in order to maintain the performance of the instrument.

If the images shown on ESA’s ‘The Sun now’ web page display the message 'CCD BAKEOUT', then this means EIT images are temporarily unavailable. In this case, there is nothing wrong with SOHO's EIT instrument. The images will resume within 2-3 weeks.


2-3 WEEKS?! what's really going on?


To keep the ‘readout noise’ down (i.e. suppress the ‘snow’) and also to prevent cosmic ray hits from permanently damaging the detector, the EIT CCD is usually operated at a temperature of about -67 °C. This very low temperature is achieved by keeping the CCD chip in thermal contact with a titanium ‘cold finger’ that is attached to a radiator plate.

Bakeouts are scheduled during periods when data loss is expected, for example during telemetry ‘keyholes’ (periods when SOHO is in limited contact with Earth)


So, evidently SOHO only has one EIT telescope not in a telemetry keyhole, which is good neews, however I'm still curious as to why it takes 2 - 3 weeks to get the HGA back into alignment for data feed...

If we sent a manned mission somewhere and it experienced a telemetry keyhole, you could bet your bottom dollar they wouldn't have to wait 2 - 3 weeks to reestablish communications...

Their explanation What is a 'keyhole', anyway? gives a pretty detailed account on why this happens... however, thier operations page links to thier SOHO Calendar — 2010 Coordinated Observations schedule, which reveals:

Apr 22-May 3 D27 Keyhole (Apr 24-May 01 34m Keyhole)



So I am to assume the 2 - 3 week window they describe will most likely only last to about May 3rd. Is that an educated guess?











.




posted on May, 2 2010 @ 10:02 AM
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Huh . And now we get this . Venus broke in two? can anyone explain this?www.youtube.com...

[edit on 2-5-2010 by bluemooone2]

[edit on 2-5-2010 by bluemooone2]



posted on May, 2 2010 @ 10:24 AM
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And before they released that we had this : www.youtube.com...
Im really beginning to think somethings up.



posted on May, 2 2010 @ 11:40 AM
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reply to post by bluemooone2
 


This is some really intriging stuff

Can anyone explain ?



posted on May, 2 2010 @ 12:09 PM
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reply to post by bluemooone2
 


The double effect is due to a phenomenon called "blooming" aka "pixel spillover". It is very common in CCD's. Basically, the CCD is just a array of photosensitive semiconductor material. The array is divided into pixels, and generally if the light falling on one pixel is very strong enough, it breaks the quantum well of that particular pixel and spills over to the next pixel. Resulting in streaks and also double images.

blooming




posted on May, 2 2010 @ 12:14 PM
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reply to post by peacejet
 


That makes sense then. OK Thanks for that.



posted on May, 2 2010 @ 12:16 PM
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reply to post by bluemooone2
 


Happens every time. 2008:



posted on May, 2 2010 @ 12:30 PM
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reply to post by DarkspARCS
 



If we sent a manned mission somewhere and it experienced a telemetry keyhole, you could bet your bottom dollar they wouldn't have to wait 2 - 3 weeks to reestablish communications...


The main reason why SOHO goes into a blackout is because of its orbit. It is in an L1 orbit in the Sun-Earth system in a halo configuration.

L1 orbit

Halo orbit

more info

This is to ensure that the spacecraft is in view of the Sun all the time for observation and also in view of earth for easy communication. And also L1 orbit is preferred because the gravity of earth and sun balance each other and the spacecraft just remains suspended with no need for orbit changes. To get a spacecraft out of such a orbit, you need an very large rocket for imparting sufficient orbital escape velocity(and it is difficult considering the distances involved). So, any spacecraft sent into such a orbit is generally destined to remain there forever. But future astronauts who spend time in deep space must return to earth. Hence, this orbit will not be followed and this communication problem will not occur.

In my opinion, data unavailability due to communication keyhole should not be considered as bakeout. Bakeout is intrinsic to the ccd chip alone. And this event occurs mostly during times of extreme solar activity.



posted on May, 2 2010 @ 04:21 PM
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I believe SOHO and Lasco are back up.
Second line



posted on May, 3 2010 @ 04:04 PM
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Originally posted by Sinter Klaas
reply to post by bluemooone2
 


This is some really intriging stuff

Can anyone explain ?



The might Phage shall answer this. Just poking fun at you phage.



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