# Tag Info

14

At least for the Space Shuttle, commands to the orbiter from the ground were routinely encrypted. Communications Security Communications security (COMSEC) equipment provides the capability for encryption / decryption of operational data aboard the orbiter. The COMSEC equipment works with the NSPs to provide selectable transmit, receive, and ...

13

There is some indirect evidence that Arecibo's loss has already impacted communication with some of the deep space probes. NASA's official statement on Arecibo says this: NASA’s Goldstone Observatory in California, another planetary radar, recently returned to full operations after successful delivery and testing of a new klystron tube for its high-power ...

13

A few months before Cassini made its mission-ending dive into Saturn's atmosphere, it skirted the region between Saturn's atmosphere and the innermost ring. From NASA Spacecraft Dives Between Saturn and Its Rings, emphasis mine, The gap between the rings and the top of Saturn's atmosphere is about 1,500 miles (2,000 kilometers) wide. The best models for the ...

11

There is currently a push in the United States to expand mobile phone and data service. In particular, 5th generation (5G) uses part of the telecommunications C band. However, Intelsat already has a license for and is using part of the same band. Washington, D.C. – October 28, 2019 – The C-Band Alliance (CBA) announced today that it will commit to clear ...

7

Early satellites were not protected. In fact there was at least one case where satellite was lost because rogue radio transmission got into command link and at least another (Kosmos-785, 1975) where spontaneous error in transmission was misinterpreted as self-destruction command. Security through obscurity (and a need to use fairly expensive and bulky ...

6

Yes, it is possible. Radius of Earth:$6,378 \mathrm{km}$ Radius of the Moon: $1,737\mathrm{km}$ Semimajor Axis of the Moon's orbit: $384,000 \mathrm{km}$ Minimum distance from Earth to Mars: $54,600,000 \mathrm{km}$ Since the maximum difference in distance between the Earth and the moon is roughly 0.7% the minimum distance between Earth and Mars, you can ...

6

Yes! It is know as the "Delay Tolerant Network" [1] (prior versions called this the "Disruption Tolerance Network" [2]). It is currently undergoing standardization by the CCSDS. [3] The protocol itself is called the "Bundle Protocol", and an implementation of the BP is available as an open-source Core Flight System application. [...

6

We communicate via radio, as you note, but it's not quite as hard as your question makes it sound. Don't get me wrong, it's still an amazing feat of engineering, but we can walk through how it's possible. First, we can think of this by way of an analogy. You might think that this is like being in a stadium at night, with huge, bright, white lights shining ...

5

This happened on the first Spacelab flight, STS-9. For the 1983 ham radio contact mentioned above, what wavelength... All ham radio operation for STS-9 will be in the Amateur Radio 2-meter band (144-148 MHz), Dr. Garriott's transceiver will have the capacity to transmit and receive on channels 20-kHz apart. The planned operating frequency range is: Space-to-...

4

In 2014 China and Argentina signed an agreement that allowed China to establish and operate a deep space station in Argentina. According to Reuters, the Chinese military runs the station in Argentina. The site is on a 200 ha compound, in a remote part of Argentina. While it still has access to an Australian space dish, at Yatharagga in Western Australia, ...

4

There is a Chinese run ground station in Swakopmund, Namibia. Image source This station is part of the "Chinese Tracking, Telemetry, Command and Communications System", which has similar stations also in Karachi, Pakistan and Malindi, Kenya. See https://en.wikipedia.org/wiki/Swakopmund_tracking_station for more information.

4

It seems to me they made it as open as they could and still have it work, but that's probably not quite open enough to gather the signal on your own without some significant effort. The best source I've found on the signal itself is Juno Telecommunications (2012), with "Detecting Juno's ‘Heartbeat’" (2020) as runner-up, and Juno Raw Data (Level 0) ...

4

tl;dr: Anyone with the capability is either working with NASA or has better things to do with their dish. Nobody except DSN, has ever heard an American rover or lander transmitting from Mars. This is not true. Both Green Bank Observatory and Max Planck Institute for Radio Astronomy received signals from the Perseverance EDL (entry, descent, landing) using ...

4

Yes, Venera-4 had a radiator-cooler in the center of its dish. From https://www.laspace.ru/projects/planets/venera-4/ Передача информации со скоростью 64 бита в секунду осуществлялась через параболическую остронаправленную антенну (ОНА) диаметром ~2,3 метра. ОНА состояла из жесткой центральной части, в которую был встроен радиатор–охладитель, и раскрываемой ...

4

Doing a scaling process from the performance of the telecommunications ("telecom") system of NASA's Cassini spacecraft at Saturn, I estimate the system you describe could support a data rate of a bit under 7 kbps, if the signal is received at a NASA DSN station's 34-m (diameter) antenna. If a 70-m antenna were used instead, that rate would jump to ...

3

It's obviously more than just dish size and bolting on a new receiver as, for example, the 32 m Cheia antennas cannot receive X-Band, but the 32 m GHY-6 at Goonhilly can. What are some details to consider? The limiting factor when uprating a parabolic reflector antenna to a higher frequency is usually the surface roughness/shape error. Basically, the ...

3

That is a very simple geometric problem. Imagine a globe on your desk and two table tennis balls. You hold one ball at one side of the globe and the other ball on exactly the opposite side of the globe. You notice that these balls can't 'see' each other, no matter how large or small the distance between the balls and the globe is. Now imagine both balls in ...

3

Spectrum to telecom is like real estate to commerce. To provide services you need real estates. Clearing the spectrum basically means to vacate from it. In this case, Intelset is trying to vacate C-band and then sell it to 5G operators. To achieve this they need to migrate existing C-band services to some new frequencies, but they don't quite have the cash ...

3

There is a giant committee set up among all the space powers to coordinate this. From the ESA page: http://www.esa.int/esapub/bulletin/bulletin121/bul121e_marelli.pdf "The Space Frequency Coordination Group (SFCG): The SFCG was created 24 years ago as an ESA and NASA initiative. It is an informal group composed of frequency managers from all of the ...

2

That temp ( ~ 1550 K ) looks suspiciously like the maximum Zodiacal dust grain temp before sublimation Thus the dominant thermal blackbody background Voyager is likely to ever see : " https://www.researchgate.net/figure/Dust-grain-equilibrium-temperatures-vs-distance-from-the-host-star-KIC-3542116-for_fig5_319210038 "

2

This is an interesting but challenging question. I've found the following footnote on page 39 of Voyager Telecommunications, DESCANSO Design and Performance Summary Series, Article 4 Section 7.2.6 Voyager 2 Procedures to Compensate for Voyager 2 Receiver Problem and so am posting as a partial answer for now. I will have to dig deeper and then update ...

2

Supplemental answer with additional background: Arthur C. Clarke explains it in their 1945 article Extra-Terrestrial Relays; Can Rocket Stations give World-wide Ratio Coverage? in Wireless World's October 1945 edition. (text version) A screen shot of a bit of the page from the link above is shown below. As far as I can tell Clarke doesn't spell out exactly ...

2

Does SPICE function gftfov account for occultations? Almost certainly not. The documentation does not indicate that gftfov does this. The documentation instead implies that this is purely a geometric calculation based on the field of view of the instrument and the position of the target, possibly with corrections for the shape of the target and corrections ...

2

Question: Is there any information at all that describes and quantifies the radio opacity of rocket exhaust? Has this (or related interactions) ever been discussed in detail or even measured in the context of spaceflight? I approach this with dread due to my well known aversion to anything dealing with electromagnetic waves; but yeah, there is such ...

2

tl;dr: It will likely have a ZigBee identifier between 1 and 240 unless they've turned that off somehow. DSN can't hear 900 MHz (I don't think) but Green Bank could indeed pick up "proof of life" if so inclined! FAST could as well, as could several large radio astronomy arrays like VLA and ALMA. Addressing is also part of the application layer. A ...

1

What does it take to upgrade a radio antenna 32 m dish antenna to receive from the surface of Mars? Per this answer to Has the Curiosity rover ever communicated directly with Earth via its high-gain antenna? Signal strength & data rate? for example, the Curiosity Rover's high gain antenna transmits at about 8.1 GHz and can be heard directly on Earth by ...

1

https://en.wikipedia.org/wiki/Beam_waveguide_antenna The wiki article is short but I think it answers the question. Non-"beam waveguide" antennas don't allow use of different receivers simultaneously. For example DSN 70-meter dishes can't receive Ka-band, but only X-band. They would require long operation of receiver change. Also receivers and ...

1

It is too late now to think about a repair. The instrument platform crashed into the dish at the first day of December.

1

Does anybody know the bandwidth of the Voyager 2 radio antenna? Well there are different bandwidths for different functions. This summary of Voyager's telecommunications systems by JPL's Deep Space Communications and Navigations Systems Center of Excellence (DESCANSO) claims Voyager has 4 main functions for communication. They are carrier tracking (Doppler),...

1

Iridium has 100 minute polar cycle time. Rx’s must be aimed properly. look for the old satellites to have solar reflections follow the grid lines and aim between 2 lanes at the optimum elevation angle which is a tradeoff but might be off 90 deg. Try direction north of vertical. Reflections may cause Rayleigh losses at low angles. therefore if you have poor ...

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