Starlink -satelites

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Ruud

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Jun 29, 2012
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www.rudecheers.wordpress.com
I visited family in southern France last week and with a sky which has a lot less light pollution than where I live I had my eyes on the skies constantly while enjoying Christmas-dinner outside.

At one point in the evening, I saw one.. two... three... SIXTY satellites passing by, all in the exact same orbit.

Insert 'satellites in the same orbit' in Google and I quickly found out it is Elon Musks' toys flying past at around 350 km's height. The project is called 'Starlink'.

https://en.wikipedia.org/…/Starlink_(satellite_constellatio…

The photos were taken with a shutter speed of around 20 seconds, so each line in the photo represents the distance each satellite covered in those 20 seconds.

DSC_5370.jpg
DSC_5370-3.jpg
DSC_5370-2.jpg
 
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demographic

Bushcrafter (boy, I've got a lot to say!)
Apr 15, 2005
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Few months ago I was out camping with a mate and we spotted a load of those.
Googled it and discovered that had just recently been launched and seperated.
Seems they have an Ion Drive unit runn8ng in Krypton to achieve final orbit and as they don't have a huge amount of thrust they use conventionel liquid fuel Falcon 9 engines to get into orbit.

Was a decent line of satellite's.
Seems that fibre optic cable over from New York to London is soon to be obsolete for its primary duty of getting a few miliseconds of drop on other traders.
The speed of light in a vacuum (space then) is faster than the speed of light in glass (fibre optic) so even if the starlink signal goes a longer distance it likely gets there faster.
Theres a delay depending on up/downlink relays and so on mind.

That means all the people who do high speed trading will pay squillions to use it. Which apparently subsidises the paupers in other countries who arent quite so bothered about those miliseconds.
 
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There are three companies that plan large LEO constellations. I expect this will become a more common sight in the future. I have very mixed emotions. Fast Internet communications from anywhere in the world is a noble goal. And seeing satellites streak overhead is always a treat. But when the skies look like the 405 Freeway in Los Angeles, I think we will have lost something special.

- Woodsorrel
 
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dwardo

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Aug 30, 2006
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There are three companies that plan large LEO constellations. I expect this will become a more common sight in the future. I have very mixed emotions. Fast Internet communications from anywhere in the world is a noble goal. And seeing satellites streak overhead is always a treat. But when the skies look like the 405 Freeway in Los Angeles, I think we will have lost something special.

- Woodsorrel
I agree on the mixed emotions on potentially spoiling the night sky, but at the same time it makes it much harder for tinpot dictators to "turn the internet off" or have state monitored internet. Mentioning no names.
 

demographic

Bushcrafter (boy, I've got a lot to say!)
Apr 15, 2005
4,152
175
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Aye, I'm not right sure how I feel about thousands of satellite's kicking about in low earth orbit either.

The technology involved in the launch is fascinating and looking at the huge amount thats going on in various space programmes is an education.
Still a hell of a lot of satellite's though eh?
 
Not really well read on satellite technology so can someone explain to me why they can't be matt black and invisible please?
I will try.

There are two reasons that immediately spring to mind why this may not be practical.

Thermal design
Space is a vacuum, so spacecraft cool through radiation. There is no convective or conductive cooling like we experience when we are hiking in a cold wind or lying on frozen ground.

So spacecraft must be designed thermally to balance the spacecraft's thermal emissivity (how much it radiates) with the amount of heat generated by its electronics and the energy it absorbs from the sun. When the spacecraft is in sunlight a white or metallic spacecraft will absorb less energy from the sun. A darker spacecraft may have a heating problem.

When the spacecraft is in eclipse (over the side of the Earth away from the sun), it can use electrically powered heaters to keep itself warm. So it is better to design the color of the spacecraft to help it keep from overheating in sunlight. Because there is a good solution to keeping it warm in eclipse.

Solar Power
When we see the spacecraft overhead, we often see sunlight reflecting from the structure of the solar panels. If you have been in the wilderness and witnessed an Iridium flare, it is something you will never forget. You are seeing sunlight bounce off the large spacecraft structure and the structure surrounding the solar panels. It makes you feel like you are in a science fiction movie.


I am guessing these two reasons are why commercial satellites will not be painted black in the near future.

- Woodsorrel
 
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Janne

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Feb 10, 2016
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I have always wondered why we pollute the space around our planet with tens of thousands of small, disposable devices.
Would it not be better to have a number of large units, international, where new tech could be attached, after removing the old tech?

I suppose these small satellites will eventually fall back to Earth?
I mean, surely they can not let them float there, as space junk?
 
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I have always wondered why we pollute the space around our planet with tens of thousands of small, disposable devices.
Would it not be better to have a number of large units, international, where new tech could be attached, after removing the old tech?

I suppose these small satellites will eventually fall back to Earth?
I mean, surely they can not let them float there, as space junk?
Janne, right now everyone builds their own spacecraft independently. Small spacecraft = small mass = lower costs to launch = less expensive. So there is no movement to build larger orbiting platforms.

For Low Earth Orbit spacecraft (below 600 km) I believe there are regulations that they must deorbit within 25 years. A bigger problem is all the detritus we've created. Everything from bags of human waste to lost bolts and debris from launch vehicles. These are much harder to track and avoid. If we are not careful, we may create a wall of debris around the planet, trapping our species on Earth. I believe there are people thinking about and working on this problem.

- Woodsorrel