44 votes
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What impact will the deorbiting of thousands of satellites have on the atmosphere?

Not much research has been done on this question in recent years, but some researchers are worried enough to research into wooden satellites. The question on the environmental impact of deorbiting ...
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  • 11.1k
34 votes
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How do the Starlink satellites shine?

Starlink (and other satellites) categorically do not have exterior lights or illumination, that would be a waste of power for no particular benefit. The reason that we can sometimes see satellites ...
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  • 14.6k
33 votes

What impact will the deorbiting of thousands of satellites have on the atmosphere?

The mass of Earth's atmosphere is 5E+18 kg and the Troposphere alone has 3/4's of that. With an average height of 13 km that makes its volume $4 \pi r^2 h$ or about 6.6E+18 m^3. If we break up one ...
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  • 148k
32 votes
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Why will Starlink satellites use krypton instead of xenon for electric propulsion?

It's the same reason SpaceX often does things differently: Krypton is a lot cheaper. The satellites are designed to control costs. For example, each will maneuver with Hall-effect thrusters—ion ...
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  • 121k
25 votes
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Why does the Falcon 9 launch 60 instead of 100 Starlink satellites at a time?

To begin with, Starlink sats have a mass of ~260kg not 227kg. Secondly, the reusable Falcon 9 LEO payload has a limit of around ~15600kg; the 22,800kg payload is for expendable Falcon 9. 60sats*260kg =...
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15 votes
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Main differences between 5G and Starlink?

Starlink and 5G don't have that much to do with each other--they compete for different customers. Starlink systems currently require a large receiver the size of a pizza box to uplink to satellites. ...
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  • 14.6k
14 votes
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Is the Starlink array really visible from Earth?

Yes, the Starlink satellites were visible from earth with your naked eye and have been seen and recorded by several people. See also https://vimeo.com/338361997 and read about it here. Gizmodo: ...
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  • 12.2k
14 votes
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Is it feasible to paint SpaceX Starlink satellites black so as not to frequently saturate the CCDs of the Large Synoptic Survey Telescope?

In general satellites are not "painted". They are covered in a variety of Multi-Layer Insulation (MLI) blankets with varying optical qualities. I have seen MLI in silver, black, and gold - sometimes ...
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  • 4,129
13 votes
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Which satellite constellations are already operational in LEO (Low Earth Orbit)?

Is there a webpage where I can see the list of LEO satellite constellations? Yes! Celestrak has several pre-arranged groups of satellites and many of those groups can be seen as constellations, and a ...
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  • 148k
13 votes
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Satellites - predominant apparent motion?

Launching west to east requires less fuel. An object in low earth orbit is moving horizontally at around 8km/s. Launching a satellite in the west-east direction allows you to take advantage of the ...
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11 votes

What are the bottlenecks stopping SpaceX from launching more frequent batches of Starlink?

The answer, like many things in the business world, revolve around money and time. Building/developing a satellite, let alone a satellite assembly line capable of pumping out thousands of satellites, ...
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  • 14.6k
11 votes
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Can the Indian government ask SpaceX to pay for bandwidth usage in its airspace?

In order to transmit from a country, one must have a license to do so, with the exception of some spaces without specific owners, like WiFi's 2.4 GHz that allows small narrow transition can work. It ...
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  • 118k
10 votes

Why is one Starlink satellite not following the adjacent one in this image?

Basically they are not quite in the same plane. As a satellite raises or lowers, not only does it change the relative position within an orbital plane, it also will slowly shift the longitude of the ...
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  • 118k
10 votes
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Is SpaceX propulsively deorbiting a Starlink satellite already?

Yes! The current status (end of June 2019) according to a SpaceX statement via Michael Sheetz is: 45 in final orbits 5 still raising, in final orbits shortly 5 paused during raise for adjustments, ...
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  • 5,027
10 votes

Can the Indian government ask SpaceX to pay for bandwidth usage in its airspace?

The answer is No, largely based on the fact that India is a signatory to the 1967 Outer Space Treaty. If you pick a country that didn’t sign any of the patchwork of treaties covering space, it could ...
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9 votes

How do the Starlink satellites shine?

I'm going to answer a slightly different question from the other answer: "why are Starlink satellites so visible, compared to other satellites?" The answer is that they're very close to the earth; ...
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9 votes
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Have astronauts seen Starlink trains?

Yes, it happened at least on 13th April 2020 at 21:25:02 UTC: https://sattrackcam.blogspot.com/2020/04/starlink-train-photographed-from.html The image above (image ISS062-E-148365, original at high ...
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  • 974
8 votes
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Do the latest Starlink satellites use inter-satellite laser communications?

All I could find was here which led to a variety of articles which explain the technology in depth. Not that Wikipedia is always reliable, however it stated that: The satellites will employ optical ...
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8 votes
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Starlink's autonomous collision avoidance

I don't think there are any papers about it, but here's what I've gleamed from my studies on it. As you mentioned, they use information from the DOD, specifically Space-Track, or C-SPOC, or J-SPOC. ...
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  • 118k
8 votes

Why is SpaceX deploying Starlink satellites without inter-satellite communication capability?

Without the mesh network SpaceX cannot provide global service as originally assumed. A potential (but unsourced) model for what they have is similar to terrestrial mobile internet with ground stations ...
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8 votes
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How close were Starlink-1095 and Starlink-2305 to the Tiangong Chinese Space Station?

Jonathan McDowell, an astrophysicist at the Harvard-Smithsonian Center for Astrophysics, did calculations regarding how close the Chinese Space Station came to S-2305, and it's quite close. A reply in ...
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7 votes
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Which of the recently launched Starlink satellites is the coated one?

In the NORAD database, it is 71130 / STARLINK-1130 and has the additional designation DARKSAT. Or as 2020-001BL. https://celestrak.com/NORAD/elements/supplemental/table.php?tleFile=starlink update: ...
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  • 5,742
7 votes
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Astrophotographer Thierry Legault is not convinced that DarkSat is darker than the others. Have photometric measurements been reported?

I was able to measure STARLINK 1130 (darksat, left) on March 19th, 2020, at Sternwarte Mirasteilas. Comparison object is STARLINK 1084 (same operational height, similar altitude above the horizon, ...
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  • 448
6 votes
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What performance specification would be lower for Krypton than for Xenon in Hall effect thrusters?

Hall effect thrusters do not use strong magnetic fields and radio frequency power to heat electrons to high energy for ionization of the gas. Instead they rely on a DC current of electrons accelerated ...
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6 votes
Accepted

What are Starlink's available momentum unloading strategies?

Per Elon via twitter, magnetic torquers. Magnetic torque rods for desaturation of momentum wheels.
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  • 5,742
6 votes

Delta-V of Starlink Satellites

update: It's been two years and Starlinks are now being deployed at much lower altitudes! I am revising this "ballpark spherical-cow envelope-back estimate" based on @BrendanLuke15's answer ...
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  • 148k
6 votes

Why is SpaceX deploying Starlink satellites without inter-satellite communication capability?

http://www.circleid.com/posts/20191230_starlink_simulation_low_latency_without_intersatellite_laser_links/ This study claims that even without the inter satellite laser system, the latency is ...
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6 votes
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Is Starlink VisorSat really dimmer?

Initial observations of the Visorsat put it a mag 7 in final orbit; however larger collections of observations from amateur sat watchers put it at ~mag 6. Since then further observations by ...
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6 votes
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Why didn't SpaceX see that geomagnetic storm coming? Was this a fluke or could this happen more frequently in the future? (R.I.P. 40 lost starlinks)

I think one possible reason that they didn’t see it coming was that the it was extreme ultraviolet photons that only took roughly 8 minutes to travel from the sun and to start heating the thermosphere....
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  • 217
5 votes
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Can / should the Starlink satellites be blackened?

They have said that they will mitigate the reflectivity of the satellites in future batches and that the 1.0 launch, Nov 11 they did not complete that for this batch. In the December 2019 launch they ...
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