Too many Earth-Satellites..

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brian livesey
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Too many Earth-Satellites..

Post by brian livesey »

The International Astronomical Union has criticised space launch company,SpaceX, for launching 60 satellites in its Starlink network to provide internet coverage for the whole planet. The IAU said that constellations of satellites threaten the principle of a "dark, radio-quiet sky" as "a resource for all humanity".
SpaceX boss Elon Musk, driven by an incessant urge to line his pockets, has been given permission from the US Federal Communications Commission to put a total of 11,000 satellites in orbit. Meanwhile, One Web and Amazon have plans for their own satellite constellations, the latter aiming to put 3000 plus satellites in orbit.
The Royal Astronomical Society said that there had been no prior consultation on what might bring "a significant and lasting change to views of the night sky, until now enjoyed throughout history and human prehistory". A concern is that myriad light-reflecting satellites could disrupt sensitive ground-based optical telescopes, such as the Extremely Large Telescope, still being constructed in Chile. Musk has retorted that telescopes should be placed in orbit above interference, but the cost of such a move would be truly astronomical.
The issue of radio interference from a multitude of satellites could have profound consequences for radio astronomy. The IAU warned: "Recent advances in radio astronomy, such as producing the first image of a black hole or understanding more about the formation of planetary systems, were only possible through concerted efforts in safeguarding the radio sky from interference." The team on the Square Kilometre Array, the biggest radio telescope of all, still under construction in Australia and South Africa, has expressed its concern.
There are further concerns that frequency clashes could affect meteorological satellites. Whether commercial interests will get away with continually deluging the night sky with their communications hardware, remains to be seen... .
Last edited by brian livesey on Sat Jun 22, 2019 9:40 am, edited 1 time in total.
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David Frydman
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Re: Too many Earth-Satellites..

Post by David Frydman »

Personally, I am furious that Musk, Bezos and others weren't immediately blacklisted by the scientific community and all astronomers.
World leaders are also pathetic and totally irresponsible.

In my opinion the initial response was also pathetic.

As I have written elsewhere, I was a member and donor of Prof. O'Neill's Space Studies Institute in the 1970s, and thought that this was the future for mankind.
This planned cities of 100,000 people in space, using material mined from the Moon.
I think Bezos studied under prof. O'Neill and plans cities of one million with trillions of humans in space.

The fatal flaw is that our planet is much more fragile than I thought, and mankind is a voracious destroyer of everything. Probably, the human condition.

I don't know the present estimates, but I have seen that maybe 500 million habitable planets exist in our galaxy.
If only 1 million have advanced life, then this life existing at the same time as us would be rare.
Say a human type species exists for a million years. The planetary time scale is billions of years, so only 1,000 would exist at the same time.
But, going by the damage we have done in only 100 years, I think that most planets with advanced life will be failed planets, destroyed by their own species.
The quest for more information about exoplanets, is severely affected by Messrs. Musk, Bezos and others present behaviour.

We have totally polluted our land and our oceans and now space.
As we have no effective world organisations, then I think this damage is unstoppable.

Regards,
David
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Re: Too many Earth-Satellites..

Post by skyhawk »

The only time this and poverty, war and everything else will end is when/if there is anything close to a global government and one world, not individual countries, in other words......... never
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Re: Too many Earth-Satellites..

Post by Brian »

It is a disgrace. The World's oldest science destroyed by money-grabbing jackasses :evil:

Maybe the next Carrington-scale event will clear out a few of them :wink:
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stella
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Re: Too many Earth-Satellites..

Post by stella »

What a lot of jackasses.

Iridium flares (which many, many astrophotographers were happy to image) are
(or were) 1,000,000 times brighter than the starlink satellites.
Yet there were no complaints during the 22 reign of the Iridium constellation.

There might be grounds for complaint when there are 1,000,000 starlink
satellites in orbit.
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Re: Too many Earth-Satellites..

Post by brian livesey »

Thanks Stella for putting the problem in perspective.
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Re: Too many Earth-Satellites..

Post by David Frydman »

1). The Iridium satellites had a maximum flare magnitude of minus 8.5 to minus 9.5 claimed.
The Starlink satellite flares are about magnitude 0 to magnitude minus 1.5 claimed.
The Iridium flares are 8 magnitudes brighter than the Starlink flares.
This is 1,600 times brighter, not 1,000,000 times brighter.
One has to compare like with like.

There were less than 100 Iridium satellites, about one per 400 square degrees of sky on average.
With 20,000 satellites there is one satellite per 2 square degrees of sky on average.
The current telescopes being built are much more sensitive than the ones in the Iridium era. Some cover very wide areas of sky.
The positions of the Iridium flares were well known, not so with 20,000 satellites.
There is visible light, infra red and radio wavelengths to be considered.

2).
a). Musk claims that the Starlink stellites are for the 'Benefit of humanity'.
b). The estimated value of the Starlink satellites programme is $120,000,000,000 to the Musk Corp.
I will leave it to the reader to judge whether Musk's actions are due to a) or b).

3). The RAS, IAU and other respected bodies statements do not consider that 20,000 Satarlink, Bezos and two others satellites pose no harm to astronomy and humanity in general.
They state the opposite.

4). Just because something can be done, does not mean it should be done.

5). Money and power trump ethics, morality and wisdom.

Regards,
David
Brian
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Re: Too many Earth-Satellites..

Post by Brian »

Thank you David for adding balance to the perspective,

regards,
Brian
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brian livesey
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Re: Too many Earth-Satellites..

Post by brian livesey »

Now the Ministry of Defence is expressing concern about the satellite clutter overhead. According to a brief press report, a group of volunteer astronomers has been enlisted by the MoD to monitor small fridge-sized objects in Earth orbit.
The astronomers are members of the Basingstoke Astronomical Society. The project aims to monitor objects with a network of low-cost cameras to improve situational data for the MoD experts.
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Re: Too many Earth-Satellites..

Post by David Frydman »

Considering how slowly the MOD usually operate, this seems a rather fast response.

In my opinion, and I am biased, the correct action for the body allowing space launches should be to just withdraw permission for any of these these large constellation satellites.

But it would not surprise me if this regulatory body has been got at by the billions of dollars at stake here.

It is estimated that Musk will be the richest man in the world with a personal wealth of $300 billion in four years because of his Starlink.
I do not object to anybody being the wealthiest man in the world or having this amount of money if getting it is not harmful.
In this case opening the way for tens of thousands of vermin satellites is very harmful.

For me it doesn't matter, as I will not be here to see what 14 billion humans and total pollution has in store for our world.
I am glad I don't have children or grandchildren.

Regards,
David
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Re: Too many Earth-Satellites..

Post by JohnM »

I saw the article on the BAS - DSTL satellite imaging in Astronomy Now and also saw a presentation on this at The National Astronomy Meeting last week. I am not sure what the objecxtive was as the systems used were not at the cutting edge. There are others available with a lot higher Étendue which translates to a higher sensitivity. The best I am aware of is the 85mm f1.2 Canon lens coupled to a Sony A7s as Nick James used to video the starlink constellation. I wondered why his images were so much 'deeper' than mine which only showed hints of the satellites. When I did the calculations his system is about 100 times ( 5 magnitudes) more sensitive than mine :-(

Also the MoD used to have some very large Baker-Nunn schmitt cameras specifically designed for satellite recording - these would seem a better option for recording satellites & space junk but they have probably scrapped them ! Even if they have them they need a large field flatter as well as a very large CCD to make the best use of them.
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stella
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Re: Too many Earth-Satellites..

Post by stella »

The MOD had Hewitt cameras not Baker-Nunn Schmidts
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Re: Too many Earth-Satellites..

Post by David Frydman »

The Baker Nunns were 20 inch aperture f/0.75. I.e. 375mm f/0.75. They weighed about 3 tons each.
Leica made a 90mm f/1.0. I think Leica Elcan (Canada).
One sold not too long ago for perhaps £60,000.

I have seen a 14 inch f/0.75 lens mounted on the back of a truck. It weighed about 350 lbs from memory. It was used for NASA rocket launches.

I had the De Oude Delft Rayxar 65mm f/0.75. Although designed for x ray work, some people have mounted these on Sony Alpha cameras. I also had a 50mm f/0.75.

I have seen 6 Rayxar 150mm f/0.75 which were used for satellite work.
They also made a 250mm f/0.75 Rayxar.
These Rayxars were made of throrium glass, so probably only f/1.0 nowadays due to browning of the glass.
The problem with these f/0.75 lenses is very short back focus, but they can probably be used on a Sony A7S with its short register. This is the advantage of mirrorless.
The Vinten F95 had a special version for the 1.5 inch and 1.75 inch Leica Elcans with a modified shutter blind. The normal Vinten F95 used 3 inch, 6 inch and 12 inch Leica Elcans.
Also earlier TTH and RTH lenses, again with short back focus.

My 180mm f/1.3 Zoomar was very good on half frame. It was a movie single frame lens. I mounted it on my Minolta SRT 303b. Actually I mounted the camera on the lens. Photos were good but a curved field meant slightly soft edges on full frame. Difficult to hand hold.

The 240mm f/1.2 Zoomar was for medium format such as Pentax 6x7.

I have the Wild Falconer 98mm f/1.4, which was used on the Vinten F95 on 70mm double sprocket film up to about 8 frames a second.
Wild also made the 98mm f/1.0.

Wray made an f/0.57 lens.

Zeiss made 10 special Carl Zeiss Planar 50mm f/0.7 lenses for satellite photography and the Apollo moon landings. Stanley Kubrick, The director of the Barry Lyndon movie managed to buy three of these lenses for scenes that just used candlelight. NASA bought six and Zeiss kept one. NASA used them for photographing the far side of the moon.

Zeiss also made an f/0.35 approx refractive lens, but it doesn't really work as a taking lens. It was a hash up using condenser lenses on a fast lens. It was made for fun, but also sold for perhaps £80,000? at auction. They just wanted to make the world's fastest refractor lens.
There was an elliptical mirror lens of f/0.5.
There are some very fast Russian lenses.

The gas board had a batch of small f/1.0 mirror lenses made up by Sinden?

There is a U.K. firm that makes 300mm f/1.0 Schmidt lenses and say they can make up to 500mm f/1.0. They will cost a bit.

I Also had the Canon 50mm f/0.95. But I gave it to a friend for his low light camera about 1980. This took photos in apparent complete darkness. The lens was the relay lens with 6 Konica 135mm f/2.8 taking lenses and a British image intensifier.

I have a Philips, Holland 100mm f/1.0. To me this looks like a Zeiss lens made for Philips research laboratory.

My Sony A7S Mk 1 with the Samyang 85mm f/1.4 lens gets 8th magnitude stars in severe light pollution in 1/13th second at 51,000 and 102.000 ISO.
This is the maximum exposure in my location. I only use single exposures and fine JPEGs.
I do use an Ergo mount for the Sony A7S and Samyang 85mm f/1.4 as this combination is not steady on telephone catalogues.

I saw a whole warehouse of special fast lenses that were used for satellite work, but was not allowed to photograph them.

Regards,
David
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Re: Too many Earth-Satellites..

Post by JohnM »

Hello David,

Don't forget the two ? Hewitt Satelite tracking cameras. See http://www.royalobservatorygreenwich.or ... ticle=1097 for a bit of history and the Hurstmonceux Science Centre at https://www.the-observatory.org/dome-c.

These are quoted as Aperture 860mm, 680mm focal length, f/1 though something there does not compute.

At the moment it is out of use but presumably could be refurbished and a CCD installed in place of the plate holder though a 100 mm diameter CCD would be quite expensive. Not sure how much EEV (as was) charge for theit buttable CCDs ? The representative I met the other day was unwilling to quote a price - a lot depends on the number of defects you are willing to accept. At least you would not have to cool it much for the short exposures.

Not sure what the status of the one in Australia is.

I have a spreadsheet that attempts to calculate the telescope 'efficiency' for tracking satellites. If anyone is interested in a copy please PM me and I will send a copy. I should stress it is untested but seems to give reasonable results. At present it can only be used for comparisons and needs some work on the sections that calculates how many photons are received in a pixel. In particular I have not worked out how to calculate the apparent angular velocity at other than the Zenith - this is needed to determine how long the satellite is visible to each pixel and thus how many photons are received.

John Murrell

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David Frydman
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Re: Too many Earth-Satellites..

Post by David Frydman »

Hi John,
I don't actually recall the Hewitt cameras, thanks.
The correcting plate is given as 630mm, so indeed f/1.0.
However, the T number may be T/1.15.

As with Maksutovs the primaries are oversize.

I cannot recall, but I think that the Baker Nunns were 20 inch front aperture, about a dozen of them late 1950s?

I think the U.S. were using 60 inch aperture scopes that could easily resolve shuttle tiles about 8 inch square.
There may be larger ones.
The Big Bird cameras were about 70 inch aperture looking down. There were larger ones also around 100 inches aperture?

There are numerous fast old lenses, but the Canon 85mm f/1.2 seems a good choice although second hand ones are suspect as I think they have to very accurately aligned.
There is I think a Samyang 85mm f/1.2.
My Samyang 85mm f/1.4 was £160 second hand. Manual focus. It is as new.

My location is so light polluted I sometimes can't see any stars with unaided eyes, but 40 stars on the Sony A7S viewfinder with the Samyang 85mm f/1.4.
I nearly always use lenses wide open. I am more concerned with getting photos rather than pretty photos, although many photos at full aperture are pretty also.

The Minolta 58mm f/1.2 had the best bokeh of any normal camera lens, although there are rivals nowadays.
Some TTH movie lenses are well known for fine bokeh.
The Speed Panchro lenses are being made again to the 1950s formulae. They are much in demand.

Regards,
David
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