Dear Mr. Andrews -

(Sorry not to make this more original, but we've had a number of questions about
these features since the Deep Space Network Central Data Recorder (CDR)
failure last week, and this is a cut-and-paste that I've been using to reply to a lot of
them. No disrespect intended, but very busy currently with writing proposals for a
Senior Review that decides whether to continue funding our missions. Please let
me know if this isn't comprehensible.)

What you're seeing are compression artifacts, highly magnified. We have to
compress the images digitally in order to keep a good rate of taking them and still
be able to telemeter them back (across an increasing distance, which weakens the
signal and limits how much data we can send per unit time) to earth. The images
you are looking at in the video are "space weather beacon mode" images that are
telemetered down nearly continuously:

in near-realtime, and are both binned (undersampled spatially, down to 512 x 512
pixels) and heavily, lossily compressed digitally onboard (analogous to the various
JPEG compression settings on a digital camera, but much more severe). Then
they're made available on the Website in a variety of magnifications or "upresings"
which only magnify the artifacts. Usually, by now (that is, three days or more after
the data were obtained), we'd have the full-resolution (2048 x 2048 pixel) images,
which are much less heavily, but still lossily, compressed, and are played back to
a Deep Space Network (DSN) ground station via the high-gain antenna on one of
the STEREO spacecraft. Unfortunately, a piece of ground hardware at DSN failed,
and we're only now catching up on the full-resolution data from January 18 onward
--- except the lower-resolution (512 x 512) beacon mode data. People first started
seeing the odd images around that date, when there was a moderate solar
energetic particle event, but those up-resed images have now been replaced on
the SSC Website with the full resolution ones. DSN has caught us up to January
20, the last time I checked.

The compression artifacts are particularly obvious when a particle (cosmic ray or
solar energetic, charged particle) hits the CCD detector on the spacecraft
head-on. (Grazing hits show up as bright streaks.) The compression scheme has
a hard time mathematically representing sharp, single- or few-pixel features, and
you get a characteristic pattern of a bright dot in the middle of a compression
block (a subsection of the image) surrounded by a pattern of dark dots.


Joe Gurman

(Dr.) Joseph B. Gurman
STEREO Project Scientist
UFOs Continued:  Spheres seen near Sun.  
Colin Andrews asked NASA "What are they?"
Reaction from a visitor to this site.

Hi Colin
I have been looking into the sun spheres anomalies. The explanations I have seen
are similar to those on your site.

What I have not had resolved is why all of the initial images (n7euA) series were
quickly removed and replaced by another series of images (n4euA) with no
explanation as to where the initial series of images went or, whether or not they
were altered somehow.

The explanation from NASA on your site seems to address this but in a very
circuitous manner.

NASA has a reputation for not being very forthcoming on errors they make or
explaining air-brushings of lunar photos.

Can you shed any light on this matter from what you have found out?

Victor Viggiani
Director of Media Relations
Exopolitics Canada

My Mars Book is being published as we speak:  two years worth of NASA flubbed
photos showing development, housing, architecture and people on Mars.

I have sent memos to NASA until I realized, they don't care what they put out.

Use my materials any way you wish.  I just want the truth to get told.

Emily Cragg

What you are seeing here is a solid object NOT compressed.

You Tube
Thanks to Stephen Balon.
Reactions to NASA's
Read at bottom page.
Posted January 28, 2010.
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