Amis du soir bonsoirs,
voila ce que j'ai trouvé sur le sujet à cette adresse:
http://www.godlikeproductions.com/forum1/message970474/pg61Quelqu'un pourrait-il en traduire les grandes lignes SVP? Mon anglais est pitoyable quoique excellent comparé aux résultats reçu par des traducteurs en ligne tel que reverso.
Je m'éscuse d'avance si c'est une co**erie mais d'aprés ce que j'ai cru comprendre,un membre du forum aurait demandé plus d'explication à la nasa sur les photos misent en ligne sur leur site et voici ci dessous ce qui semblerait être la réponse
Citation:
Did anyone at all see this? What do you think? Sounds really fishy. Why is something always going wrong when something like this happens. Something important is happening like huge asteroid going to impact, and the NASA HAL 9000-1 Computer fails and starts playing backgammon with itself.
Do we believe them? Well I find it very hard to believe and quite frankly, since all data after Jan 18 is not currently posted as they claim, then all new data can easily be manipulated.
Not bloody likely, but man are the conspiracy theorist going to have a field day on this one.
Response from HEAD NASA STEREO SCIENTIST
What you're seeing is the difference between "beacon mode" (near realtime, heavily compressed, binned [I believe 512 x 512 or smaller]) images and normal playback telemetry images (2048 x 2048 native mode, less heavily but still lossily compressed).
Normally, we get most of each day covered by the near realtime, beacon mode data through the help of a variety of ground stations around the world (including some operated by radio amateurs):
[link to stereo-ssc.nascom.nasa.gov] ,
So we have prompt information when space weather events have originated at the Sun. The full-resolution playback telemetry comes from dedicated periods of downlink ("station contacts") through NASA's Deep Space Network (DSN). A single playback can last hours, and covers data from a day or more stored on one of the two spacecrafts' solid state recorders. Those data are then played back over the Internet to the mission operations center and the STEREO science center, and thence to the instrument teams' home institutions, where they are processed over the course of a day or so. Thus, in normal operations, the full-resolution images will be ~ three days behind real time. Newer images will be the lower-res, more highly compressed beacon mode images, and older images will have been replaced by the full-res, playback data.
On January 18, at ~ 21:47 UT, the "central data recorder" at DSN, that stores all the playback data from all the missions DSN supports, failed. A backup CDR took over, but apparently started working on data from January 10, instead of just the four previous hours, as designed. (The last I heard, the DSN engineers don't understand why, but it certainly sounds like a software issue.) For some reason, DSN is unable to reset a pointer and say, please start processing from this time instead of that time. So we, and all the other missions supported by DSN, are waiting for our playback data from January 18 and all following days. As soon as we get it, and the instrument teams have reformatted the telemetry into scientifically useful formats (that allow, for instance, making SECCHI EUVI data into images), we will post the images and other STEREO browse data in the normal places.
And no, I don't know why DSN designed such an inflexible CDR system. I suspect they may modify it after this experience.
Best,
Joe Gurman
(Dr.) Joseph B. Gurman
STEREO Project Scientist
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