The Boring Sky (Sun)

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Expand view Topic review: The Boring Sky (Sun)

Re: The Boring Sky (Sun)

by GaryN » Sun Oct 30, 2022 11:14 pm

A BLUE CLOUD ON MARS
https://spaceweather.com/archive.php?vi ... &year=2022

Mars Webcam
https://www.flickr.com/photos/esa_marsw ... 462349585/

I don't see the blue in these images. Hubble does show blue in some images though.

Re: The Boring Sky (Sun)

by GaryN » Fri Sep 16, 2022 5:49 am

"It's perfectly black" -Chris Hadfield
I really like him, such a nice, polite Canadian boy! Love to meet him and buy him a beer (or 3) and ask him a few questions. He never actually came out and said he could see no stars, or the Milky way, or other planets, chose his words carefully, but of course people say he was just commenting on the background blackness, and that he could see hundreds of stars was just to be taken for granted. Most Apollo astronauts told us straight out that they could see no stars from deep space, or from the lunar surface. The greatest majority of people absolutely believe the stars are visible from space, it's what we have been told by our teachers and is of course a logical belief given the fact that they can be so impressive from Earth. Truth will out, but probably not within my lifetime.

Re: The Boring Sky (Sun)

by Cargo » Wed Sep 14, 2022 4:57 am

Cargo wrote: Thu Jan 06, 2022 5:59 am Not related to any hoax or anything, but what is really true is how a simple search for The Boring Sky (which is a pretty unique phrase on the Internet) is ignored by google and even duckduckgo hides any topic preview with this overlay:
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The Boring Sky (Sun) Beyond the boundaries of established science an avalanche of exotic ideas compete for our attention. Experts tell us that these ideas should not be permitted to take up the time of working scientists, and for the most part they are surely correct.
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I think we've really got this one solved. Space is Black. The sky is boring off planet. You can't see the Sun even.
Just re-quoting the undisturbed final result of 2 forums and 3 different topics lasting years and thousands of posts, the truth is undisputable .

As was said years ago by an eyewitness account, "It's perfectly black" -Chris Hadfield

Re: Webb Cartwheel

by Cargo » Fri Aug 26, 2022 4:27 am

GaryN wrote: Thu Aug 25, 2022 7:07 pm I was wondering what the mainstream explanation of the cartwheel would be, and this to me is hilarious.

Webb's Cartwheel Galaxy - Breakdown and Analysis
https://www.youtube.com/watch?v=qL06kS- ... dAstronomy

Of course they would think my electro-magnetic machine explanation ridiculous, but how do EUers explain it?
My god that was horrible... I could only take a few minutes of dust and mass and general nonsense spewing forth.

What annoys me the most I think is the way they talk about it like it's a dust ball rolling across the floor. Look at the 'star forming' and the 'dust'.. arggh I want to faceplant my desk.

Webb Cartwheel

by GaryN » Thu Aug 25, 2022 7:07 pm

I was wondering what the mainstream explanation of the cartwheel would be, and this to me is hilarious.

Webb's Cartwheel Galaxy - Breakdown and Analysis
https://www.youtube.com/watch?v=qL06kS- ... dAstronomy

Of course they would think my electro-magnetic machine explanation ridiculous, but how do EUers explain it?

Re: The Boring Sky (Sun)

by Holger Isenberg » Mon Jul 25, 2022 4:50 pm

GaryN wrote: Wed Jul 06, 2022 9:08 pm
Communication with CAPSTONE was fortunately reestablished now.
Yes, I wonder if they will tell us what happened?
Kind of:
https://blogs.nasa.gov/artemis/2022/07/ ... s-capstone

I guess "ranging error" means the radar pings from Earth indicated a redshift different than expected at that time. Then someone at the deep space network facility accidentally sent the wrong command and that switched off the on board radio until the on board control loop detected missing radio signals and rebooted the system which fixed it. Spatial orientation was kept during all this by the satellite itself. Maybe those commands changed during the transition from pure government spaceflight to more open business activities?

But sometimes there are just mechanical obstacles, like this bridge hit by the rocket intended for the Crew 5 flight to the ISS: https://wccftech.com/spacexs-rocket-for ... to-bridge/

Re: The Boring Sky (Sun)

by GaryN » Mon Jul 11, 2022 2:05 am

I doubt we will ever fully understand the technology incorporated in the deep space star trackers. If it were easy then I'm sure the Chinese could produce them much cheaper than the going price from the big boys. The military understand something fundamental about the propagation of EM radiation in space that is 'beyond our ken'.

World leader in star trackers
https://sodern.com/en/viseurs-etoiles/

Re: The Boring Sky (Sun)

by Holger Isenberg » Sat Jul 09, 2022 4:32 am

Further details about CAPSTONE are planned to be released I read on twitter.

Maybe it was something similar to the following event experienced with the Clementine probe to the Moon after stage separation:
Early in the mission, after stage separation, star matches were not achieved for a period of an hour. Later analysis of downlinked images showed that the 10 brightest blobs in the FPA were space debris resulting from the separation, which is a condition that was not expected in the default software.
p4 of https://digital.library.unt.edu/ark:/67 ... /86977.pdf.

That document is also interesting for another reason as it describes the miniature star tracker used for Clementine which was quite an innovation back then in the 1990s. And one detail caught my eye: a fiberoptic plate between the optical lenses and CCD. That's the same type of fiberopic plate used between the photo multiplier and CCD in the high precision star tracker I wrote in my previous reply, though here for Clementine apparently without multiplier, at least nothing is written about that in the PDF above or in the assembly instructions on https://digital.library.unt.edu/ark:/67 ... 114597.pdf.

I don't know why such a plate was used here without the image intensifier. Maybe to avoid particle contamination in zero g later during the mission or to have a defined optical property between lens and CCD independent of being in vacuum or air?

Also interesting: The CCD of the Clementine star tracker is capable of capturing 400nm - 1100nm while the radiation hardened lenses only above 500nm. That means no UV here!

Re: The Boring Sky (Sun)

by GaryN » Wed Jul 06, 2022 9:08 pm

Communication with CAPSTONE was fortunately reestablished now.
Yes, I wonder if they will tell us what happened?
I was searching for info on the navigation system and this link came up, don't see it mentioned as being part of Capstone but is amazing in comparison to the Inertial Navigation System of the Apollo days!
VN-200
https://www.vectornav.com/products/deta ... kwEALw_wcB

Re: The Boring Sky (Sun)

by Holger Isenberg » Wed Jul 06, 2022 8:54 pm

Communication with CAPSTONE was fortunately reestablished now.

About star-trackers in general I found this interesting article about the precise variants using a photo-multiplier above a phosphor coating on a fiberoptic bundle laminated directly onto the CCD/CMOS imaging sensor:

https://www.mdpi.com/1424-8220/15/6/12389

About the unit costs in general for the standard models, the cheapest for cubesats I found are around $35000 while those for larger satellites go up to $750000 in 2005: https://spacenews.com/miniature-star-tr ... -interest/

Re: The Boring Sky (Sun)

by Holger Isenberg » Wed Jul 06, 2022 3:24 am

Communication to the CAPSTONE probe lost after it reached a distance between 150 Mm and 300 Mm (depending which news article you read):
https://www.space.com/nasa-capstone-moo ... ation-loss

Wondering if the startracker model used on it has seen deep space before...

There was on the DSN now website a short blib indicated in signal 4h ago:
https://twitter.com/planet4589/status/1 ... 5657782273

But another listener couldn't capture any signal during the same time:
https://twitter.com/coastal8049/status/ ... 0789689344

Re: The Boring Sky (Sun)

by Holger Isenberg » Tue Jul 05, 2022 7:45 pm

GaryN wrote: Tue Jul 05, 2022 7:03 pm My reason would be the deep red balmer series line of hydrogen in the lunar atmosphere.

Remember 50 years ago… A famous lens made by Angénieux...

The Carl Zeiss Planar 50mm f/0.7 lens
Makes sense. And quite a surprise I now found the spectral sensitivity curve of the Kodak 2401 film which is in my interpretation the same as the Apollo 3401 except for the Apollo version made with thinner base material. At least that numbering scheme between 2xxx and 3xxx can be found documented for other Kodak films.

The spectral responsivity of the 2401 is published on the last page of https://125px.com/docs/techpubs/kodak/k ... Ti2278.pdf and showing two peaks: at 420nm and at 840nm with a usable range of 350-450 and 750-880. The normal RGB visual range from 450 - 700 is really low, less than half of the two peaks. That means the 2401 / 3401 film was UV and IR at the same time. UV of course only usable if the stellar camera has saphire lenses or similar UV-translucent material. Combined with some mentioned of UV of the stellar camera I read it could be true that the captured light is indeed only UV there, or the hydrogen IR line you pointed out.

I saw the real f/0.7 lens once at a Kubrick exhibition. That was awesome! Photos:
https://www.facebook.com/photo?fbid=102 ... 2419539601

Re: The Boring Sky (Sun)

by GaryN » Tue Jul 05, 2022 7:03 pm

But with the stellar camera only pointing away from the surface why would IR help there to see stars?
My reason would be the deep red balmer series line of hydrogen in the lunar atmosphere.

The progression of imaging methods in space goes back to the Ranger and Orbiter missions, they learned as they went and still do when it comes to the selection of filters for CCD based multispectral imaging. They soon learned that photography as we used to know it was obsolete for space based imaging, it's just too dark out there.
Looking at the Ranger missions it is clear to see that they were expecting low light levels by the specs of the cameras and lenses they used.

https://www.afcinema.com/local/cache-vi ... 1623979113
Remember 50 years ago… A famous lens made by Angénieux...
https://www.afcinema.com/Remember-50-ye ... ml?lang=fr

The Carl Zeiss Planar 50mm f/0.7 lens which was supposed to be used on the Apollo missions to show us the lunar far side was never used for some reason.

Re: The Boring Sky (Sun)

by Holger Isenberg » Tue Jul 05, 2022 4:55 pm

But with the stellar camera only pointing away from the surface why would IR help there to see stars? The decision to have the stellar camera pointing 6 degrees above the lunar limb is strange as you pointed out. What other reasons than those we discussed here would speak against pointing it straight into the zenith, like stellar cameras in reconnaissance aircrafts would do?

The 3401 stellar camera film was most likely around 125 ISO only. Look up the Plus-X Kodak film as that additional term is used in the documents above. The Kodak 2401 film was the same except for the base material being of normal thickness.

Re: The Boring Sky (Sun)

by GaryN » Sun Jul 03, 2022 5:49 am

Searching 3401 I came by this Apollo 12 report:
Apollo 12 Multispectral photography experiment.
https://books.google.ca/books?id=JFct93 ... 01&f=false

Infrared was most useful in lunar imaging and still is, as it is for Mercury too. So little visible wavelength light out there that they don't even bother with filters, anything below the IR would constitute just very low level noise.

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