Comment by wkat4242
Comment by wkat4242 4 days ago
Could you bring something like a starlink mini for backup i wonder? Id imagine this would be very worrying being stuck there as a foreigner in such a situation.
Comment by wkat4242 4 days ago
Could you bring something like a starlink mini for backup i wonder? Id imagine this would be very worrying being stuck there as a foreigner in such a situation.
> Starlink connects you to the internet via a ground station in the country where you are registered
Not true anymore.
> and the antenna will also only operate in an approved zone (depending on your country and account type). You cannot use it in China.
This is still correct.
I wasn't aware that China does this. I know India does too though, for this reason only Inmarsat is allowed there because they cooperate with the authorities (and I believe even that is subject to local licensing).
Though India doesn't have a great firewall so it's much less of an issue for foreigners visiting there.
I’m not so sure debris would help take down other satellites in that orbit. The orbit is very low so much of the debris that ends up with a deviation in its orbit will fall down. Even if it doesn’t there’s still air resistance up there which may cause more of the debris to deorbit before jt has time to hit other satellites.
And I doubt China would want to make LEO impossible to move through anyway. It’d affect China badly as well
Very expensive to take down 10-100k at once. No one today has that many antisat-capable missiles stockpiled.
Relevant, Chinese domestic media reporting on China's own perspective:
https://www.scmp.com/news/china/science/article/3178939/chin... ("China military must be able to destroy Elon Musk’s Starlink satellites if they threaten national security: scientists" (2022))
> "Researchers call for development of anti-satellite capabilities including ability to track, monitor and disable each craft / The Starlink platform with its thousands of satellites is believed to be indestructible"
"Easy to bring down" vs. "believed to be indestructible"—some tension there!
Of course it is entirely speculation. But there are previous datapoints you can look at (i.e. iran).
No it does not. Against a huge state adversary like China it does not matter. They have satellites looking down so they can quickly locate any starlink users. And then ...
The only thing that could bypass is GPS + laser links (meaning physically aiming a laser both on the ground AND on a satellite). You cannot detect that without being in the direct path of the laser (though of course you can still see the equipment aiming the laser, so it doesn't just need to work it needs to be properly disguised). That requires coherent beams (not easy, but well studied), aimed to within 2 wavelengths of distance at 160km (so your direction needs to be accurate to 2 billionths of a degree, obviously you'll need stabilization), at a moving target, using camouflaged equipment.
This is not truly beyond current technology, but you can be pretty confident even the military doesn't have this yet.
The aim doesn't need to be that accurate. Laser beams diverge due to diffraction. You can't break the laws of physics - a non-divergent laser beam would need to be infinitely wide. A 1cm wide laser beam of 700nm light will have a divergence width of approximately asin(0.0000007/0.01) which is 0.004 degrees, which is 14 arcseconds, which is very easily aimable using off-the-shelf components. People get a tracking accuracy around 1 arcsecond using standard hobbyist telescope mounts.
However, this solution is going to stop working when a cloud drifts past.
> However, this solution is going to stop working when a cloud drifts past.
Not really, because you'd be using a frequency that passes through clouds. A snow storm or hail is impenetrable, and there are weather events that cause a 1-2 second blackout, as well as cause refraction (which is mostly a challenge in reaiming the beam fast enough to compensate), but anything in the air is fine. Clouds, mist, ... But is aiming at a 1 arcsecond target moving across the sky at at least 1 degree per second from a normal (ie. moving) building really doable with "standard hobbyist telescope mounts" ?
I know 5 years ago we were still doing this with lasers on rockets toward planes, because planes can just keep their angle to a rocket essentially constant. I know there's experiments doing direct laser to satellite, no idea how well that works.
You are correct in that most "hobbyist telescope mounts" are good for tracking stars at ~1 arcsecond, only where those stars don't move across the sky very quickly (up to 15 arcseconds/second). However, it is quite within the realm of "hobbyist" telescope mounts, albeit towards the upper end, to track orbital objects. I have seen an example of a telescope mount tracking the international space station to get good images, and the tracking was pretty solid. It is assisted by a secondary telescope on the mount that helps the mount maintain good tracking, not just pre-knowledge of where the object will be.
The clouds are however much more of a problem than you're suggesting. One promising infrared band is around 10 microns, but a thick cloud will still scatter that. You'd need a 20cm wide laser beam at that wavelength for it to diverge to a beam width of around 10 arcseconds. Which is basically a reasonably-sized telescope, working in reverse.
Alternatively, you could go for millimeter waves, which would pass through the clouds reasonably well, but then you're well outside the realms of "laser" and into the standard directional dish antenna. And it'd have to be a very large dish to give you a narrow beam. For instance, a rather unsubtle 2 metre wide dish with a 1mm wavelength will give a beam that diverges by 100 arcseconds. And there will probably be omnidirectional leakage which the dastardly authorities are likely to be able to detect. At least visible and infra-red leakage can be easily blocked and concealed, but radio is much harder.
What makes it so that this kind of precision is required? I have little knowledge of the physics behind it, but a few decades ago, a local university had an open day where they bounced lasers off of a retro reflector on the moon to measure the distance: https://en.wikipedia.org/wiki/Lunar_Laser_Ranging_experiment...
The moon is 700 times farther away than the starlink satellites (or twice that, if you consider the bounce), so I find it hard to imagine that it would be impossible to communicate with much closer satellites over laser when both sides can have an active transmitter.
Starlink connects you to the internet via a ground station in the country where you are registered, and the antenna will also only operate in an approved zone (depending on your country and account type). You cannot use it in China.