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1

Radio spectrum licensing prohibits sending transmissions on the same frequency and location as where licences are granted to protect licence holders from interference. So sending commands is not permitted, except as mentioned where there are invitations to attempt to hack to help the operator identify vulnerabilities. One can always listen and in fact many ...


2

Receiving data from NASA spacecraft has happened several times, and seems to be fine. The problem is transmitting to said spacecraft where you can run in to legality issues.


9

It has a short mission because it's a test, or in fact a technology demonstration mission, not a production system. The idea is to show that the thing can be flown and will work. Once that's done it serves no purpose any more. From this page: The clock's in-space mission will validate its stability in orbit, fully characterize its long-term performance, ...


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Yes, loads! You can see the StarLink trains at Heavens Abve:


0

If the total bandwidth used was say 1 GHz then for an effective receiver temperature of 300 Kelvin the noise equivalent power of a ground station antenna will be about $k_B T \times \Delta f$ where $k_B$ is the Boltzmann constant (1.381×10-23 J/K) or about 4×10-12 Watts. If the satellite transmitted a total of 100 Watts spread over 1 GHz and over a 107 km2 ...


1

Sorry for answering my own question, but I finally got some insights on the topic. 1) Where I can find those "released documents"? According to Marco Langbroek's (the same amateur satellite tracker that took the image in the OP) excellent review on the topic: On September 6, 2016, The Intercept published a number of new documents from the Snowden ...


2

In addition to @Puffin's answer, it is becoming increasingly common for satellites to opt for dual-purpose design, where various structural and other elements serve as shielding for vulnerable components. This is as simple as making sure structural shear panels can protect propellant tanks, radiators can protect wiring harnesses, etc. To a degree, I would ...


5

In this case, we can be pretty sure it's the last stage. Objects from the same launch are COSPAR-catalogued with the same number and different letter suffices. 1986-088B is the Scout rocket body, in a 961km x 1015km orbit. 1986-088A is a satellite called Polar Bear that's orbiting at 961km x 1017km -- essentially the same orbit. Almost all satellites ...


4

If the third stage would remain in (a low) orbit, you would not need a fourth stage. The Scout G-1 was used for low orbits. Only for high payload orbits both the third and fourth stage could remain in orbits, the fourth stage higher than the third. The orbit of 1986-088B is fairly high (Min Altitude 961.2 km Mean Altitude 988.3 km Peak Altitude 1015....


2

MLI is a good example, used widely for the primary use for thermal control but has properties for a whipple shield. Looking a little further will pay off: https://en.wikipedia.org/wiki/Whipple_shield cites "There are over 100 shield configurations on the International Space Station alone, with higher-risk areas having better shielding." and in ...


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