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tdgeek

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  #2472684 28-Apr-2020 10:51
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Dunno whats going on here, my post is all over the place




Oblivian
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  #2472726 28-Apr-2020 11:37
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Resource hungry.

 

But you're welcome

 

https://james.darpinian.com/satellites/ 

 

Be a while until we see the Group 6/7 that launched last wed. But they'll be bright and close at present. (before going to higher orbit and spaced out)


elpenguino
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  #2472733 28-Apr-2020 11:58
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Handsomedan:

 

tdgeek:

 

Starlink is a satellite constellation being constructed by American company SpaceX to provide satellite Internet access. The constellation will consist of thousands of mass-produced small satellites in low Earth orbit (LEO), working in combination with ground transceivers.

 

 

So on that basis, how will spacecraft exit Earth's atmosphere in order to travel afar, if there's so many objects in geosynchronous orbit? 

 

 

The starlink constellation will be LEO (low earth orbit) which keeps their transmission power low.

 

If they were geosynchronous they'd be 3x,000 kms away and you wouldn't see them, let alone see them move in the sky.





Most of the posters in this thread are just like chimpanzees on MDMA, full of feelings of bonhomie, joy, and optimism. Fred99 8/4/21




eracode
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  #2472743 28-Apr-2020 12:16
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Just reading about the Starlink satellites. If I understand this correctly, they launch 60 of them at a time and each one weighs 227 kg. 





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Scotdownunder
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  #2472751 28-Apr-2020 12:25
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Space is big, incredibly big.  Even with the tens of thousands planned to be launched there will only be a few 'visible' at any one time, i.e. hundred of km apart.

 

These satellites are highly visible at the moment as they are bunched up while being raised from their initial orbit to their final orbit at around 350 km or higher.  Their solar panels are aligned to minimise drag while they are raised by very low power ion thrusters.  Once in their correct orbit their solar array will be aligned to the sun and will be less likely to glint in the sun.  Starlink are also investigating ways to minimise reflectivity and will provide full orbital details to astronomers to help mitigate any issues they may have.  At their low orbital height they experience significant orbital drag so will only last 5 -6 years before they will de-orbit and burn-up on re-entry.  Note this will be a controlled process as de-orbit functionality is a built in feature so no space junk here.

 

Note they will spread out once in their correct orbits and will only be visible at dawn & dusk which is not a particularly useful time to conduct astronomy.

 

Of interest to NZ is will Starlink apply for licences to operate over NZ and build a ground station in NZ.  If so they could provide high speed, low latency internet access to the remote rural parts of NZ which will never get decent internet access, far less fibre.  Our market may be small but it is incremental revenue to their main business which is to serve rural N America and other under-served areas of the world.

 

So the answer to the Simon Bridges and the mayor of Auckland's internet problems 😉


Oblivian
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  #2472767 28-Apr-2020 12:48
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The current ones are mostly in their final locations now @ 550kms.... The 7-10sec gaps between is to be the norm

 

And most still being seen under the right conditions. (Feb batch is 100kms off final). Not quite going to be going away.

 

The grouped fresh launch are only there for about 4 weeks and bright before alignment moves to raising. But they're not in our sequence just yet.


 
 
 
 

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peejayw
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  #2472833 28-Apr-2020 15:35
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You can see what satellites are overhead on this site.





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Geektastic
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  #2472859 28-Apr-2020 16:34
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There are two complete networks being launched.

 

 

 

"What’s more, Johnson worries that the swarm was an omen — of a future where just about every telescope observation conducted at twilight is marred by satellite streaks.

 

Soon, Earth may be blanketed by tens of thousands of satellites, and they’ll greatly outnumber the approximately 9,000 stars that are visible to an unaided human eye.

 

This is not some distant threat. It’s already happening. SpaceX has already put 240 of these small satellites, collectively called Starlink, in the sky. Sixty were launched this week. That will be followed by more launches, possibly every two weeks.

 

In all, the company has approval from the Federal Communications Commission to launch 12,000 satellites, and Musk is seeking approval to launch 30,000 more."






decibel
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  #2473024 28-Apr-2020 20:33
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Geektastic:

 

..In all, the company has approval from the Federal Communications Commission to launch 12,000 satellites, and Musk is seeking approval to launch 30,000 more."

 

 

This is the part that annoys me - the American FCC deciding what is good for the whole planet.


Oblivian
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  #2473026 28-Apr-2020 20:38
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Xingyun-2 (CASIC) is going for 156 Constellation

 

And I forget the other agency, but Musk is not the only one with a LEO mesh planned


Scotdownunder
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  #2473031 28-Apr-2020 20:44
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Decibel, the FCC does not regulate the launching of satellites, that is a UN function and its on a first come first served basis.  What the FCC does do is give permission to use radio transmissions while above the USofA and of course regulate the ground stations and user terminals in that country.  Equally, Starlink will have to get permission to operate over NZ from the NZ government. 


 
 
 
 

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Scotdownunder
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  #2473037 28-Apr-2020 20:53
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The UK based OneWeb network has also launched 74 satellites but it has gone into bankruptcy.  Since they were using expensive Russian rockets they were always going to have funding issues.  Starlink using SpaceX’s reusable Falcon 9’s will cost considerably less to deploy.  It will be interesting to see what they charge for service once they start commercial service later this year or early next.


jlittle
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  #2474138 30-Apr-2020 15:26
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Scotdownunder:

 

...will only be visible at dawn & dusk ...

 

 

This is the point which needs to be emphasized, as many people seem unaware of it, including posters here.  In LEO orbit the satellites are in the Earth's shadow for most of the night.





Regards, John Little


elpenguino
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  #2474186 30-Apr-2020 16:48
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in LEO orbit the satellites are in the Earth's shadow for most of the night.



Err no, in leo they'll orbit the earth every 90 minutes.
It's already not unusual to see a satellite in the existing collection of all leo devices.

I can't see how 12,000 extra Leo units won't be visual pollution for astronomers.




Most of the posters in this thread are just like chimpanzees on MDMA, full of feelings of bonhomie, joy, and optimism. Fred99 8/4/21


Oblivian
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  #2474190 30-Apr-2020 16:55
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Hes referring to standard reflective-ness from solar arrays and so on in the sun that make them visible. Generally when sun is below the horizon by more than about 40deg LEO objects reflect less and less as it goes behind earth - up till about 10pm.

 

 

 

That said, from launch 9 the next lot are meant to be orientated better and have a large blind on 1 side of the panel to stop reflecting

 

https://petapixel.com/2020/04/24/spacex-unveils-plan-to-keep-starlink-satellites-from-ruining-the-night-sky/ 

 

 


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