43

Yes. The space shuttle could. I recall in shuttle ascent abort training, when the crew was executing an East Coast Abort Landing to an airbase / airport on the East Coast, the commander would communicate with the tower on "guard" as they were approaching the site. These airports included civilian airports such as St. Johns, Wilmington, Stephenville, etc. ...


28

It depends on what you mean by "broadcast to the whole world". According to the annotated transcript (h/t to Organic Marble for finding it) John Young said it into a "hot mike", i.e. with the air-to-ground communications loop open: [In the following, John doesn't realize he still has a hot mike. Charlie is only faintly audible through John's mike and ...


27

Yes. The Soyuz Escape Capsule Responding Instructions explicitly document 121.5 MHz capability, including voice: c. Morse code: “AN” (dot, dash, dash, dot) broadcast on VHF 121.5 during descent. d. Emergency Locator Transmitter warble on VHF 121.5 interrupted only by crew broadcasts. e. Crew has a survival radio with beacon and voice capability on VHF 121....


22

It's a great question! Trajectory To get a few decades more out of them, you can launch Voyagers 3 and 4 sometime around now and get by with a maximally-boosting flyby of Jupiter since you wouldn't target Saturn as well. If you had to wait for Jupiter and Saturn to line up with the original pair's trajectories again, it would be too long of a wait. ...


15

You have a few problems with doing that which @uhoh unit has already elaborated. Even if you could surmount those you have a bigger problem, which is the Voyager probes will have to shut down their science instruments due to power constraints before a probe launched now would be able to get in a position to do any good. There are 4 instruments running on the ...


11

If the question is that if spacecraft independently initiate communications with random civilian ATC unit, the answer seems to be no. Civilian ATC units operate on VHF frequencies (118-136MHz) with AM modulation. Besides that, spacecraft should be able to tune in any frequency within the range that an ATC unit is using. Or they could use universal emergency ...


9

The Americans did worry about the possibility of Soviet interference. The navigation computer was could be updated from the ground, but this was only done after confirmation via a voice channel: Apollo’s design did reflect some early concern about possible Russian sabotage. For example, in the air-ground conversations you’d often hear the ground ask the ...


8

The wavelength dependence of the definition of free space path loss (FSPL) is an artifact of the way the receiver's antenna gain is defined in the same link budget calculation. It's referenced to an ideal isotropic antenna with a receive area of roughly 1 square wavelength, which for high frequency gets very small. If you do them together (transmit gain, ...


6

The space segment of the Cospas-Sarsat system has two components, SAR signal repeaters (SARR) and SAR signal processors (SARP). The Sarsat instruments [...], receive these messages. They are downlinked to the distress terminals — known as Local User Terminals (LUT) — distributed around the globe. The message are then processed and distress alerts ...


6

The answer is given within the question, the emergency signals are received by the the International Cospas-Sarsat Programme satellites. From wikipedia: Space segment The Cospas-Sarsat system space segment consists of SARR and/or SARP instruments aboard: Five satellites in polar low-altitude Earth orbit called LEOSARs Seven satellites in ...


5

There's no minimum power for any receiver if you don't specify the type of transmission and the amount of knowledge about that existing at the receiver! For example, a GPS receiver has way worse characteristics (for example, a 4-bit ADC) than a digital TV receiver. So, who needs higher power to work? GPS works well below the noise floor because the data ...


5

This was briefly discussed in the Dec 21 press briefing. It wasn’t a gap in the sense of “no radio waves here”. Rather, since the craft was confused about what time it was and hence what attitude it should be maintaining, it was also using antennae that weren’t optimal for acquiring the signal. The signal acquisition was slowed down due the resulting low ...


5

This is a bit of a breadcrumb trail, but page 2-99 of NASA MSC-01372-1 "Apollo Operations Handbook Extra Vehicular Mobility Unit" (March 1971) discusses the power used for Apollo 15-17: The dual mode is the normal operating position of the switch. In this mode, the EVC-2 transmits a 0.3- to 2.3-kHz voice signal and two interrange instrument group (IRIG) ...


5

Russian version of Sputnik-1 Wikipedia article has the section labeled "Sounds of Sputnik" and cites the respective technical report regarding development of the Sputnik's "radio device" D-200 (in Russian). According to the report, primary reason for transmitting on two frequencies was redundancy. The transmission frequency had to be higher than that of the ...


4

Different airports were prepped by NASA to be backup landing places all around the world. Seeing NASA would know about the emergency landing prior to them needing these alternate airports, NASA would contact the local Air Navigation Service Provider (ANSP) letting them know the shuttle was making an emergency landing. The shuttle would be treated as an ...


4

There's no such thing as a globally applicable "good" SNR. To make a earthbound comparison: While your good old analog TV needs maybe an SNR of 40 dB to be somewhat enjoyable, GPS reception on very similar frequencies can work with signal well below the noise floor, so let's say -5 dB. What SNR you'll need depends on how fast you want to transport data. ...


4

Once the communications get to earth the latency increase is minimal in comparison. In telecommunications and networking we generally use milliseconds (ms or thousanths of a second) to measure communications delay. 1.25 seconds is 1250ms. There's 2 major components to latency: Digital Signal Processing of the satellite feed, both sending and receiving: this ...


3

You can still have arbitrarily high bandwidth even with high latency (e.g., a FedEx transporter full of hard disks driving around the country has awful latency, but incredible bandwidth). If you use TCP/IP as communications protocol, you are limited by the fact that you cannot transfer more than one tcp receive windows per round trip time. Using the TCP ...


3

note: based on discussion in comments the question has been revised and more details added, so I will be updating this answer with the day. I'll address the current title: What power and signal-to-noise-ratio is required to send a signal from an asteroid to the DSN? The short answer is that it depends on the required data rate. A 12 bit 1024 x 1024 ...


3

Spectrum management is both science and art. One way of avoiding interference is using separate frequencies for different systems. If the spectrum can be confined to national boundaries, then usually it is licensed by the country administration (FCC, Ofcom etc.) however, if you want to operate a global system, the allocation must be done on an international ...


3

You can get some information from SpaceX's FCC filings for "Special Temporary Authority". There aren't always individual ones for specific launches, because certain approvals cover larger times, and they're a little broken up. For example, 0551-EX-ST-2019 covers transmissions from the first and second stages during flight, while the more-recent 2181-EX-ST-...


3

It appears to just be a carrier signal alternately transmitted and not transmitted. As the carrier is in the MHz range, the audio cannot be a direct mapping of that frequency. I don't know the specific mechanisms used to make the signal audible as a particular tone, or whether that tone would differ between different receivers. There are multiple ...


2

A few issues here: You don't "pull" information with a radio. That just isn't a thing. When transmitting, radio waves follow an inverse square law: when you double the distance, you quarter the power, which means you rapidly approach the noise floor (from cosmic radiation, solar radiation, you name it) so in order to combat noise, you need to send data ...


2

I think the answer lies in this- Forty five years ago, Motorola products transmitted astronaut Neil Armstrong’s first steps on the moon to millions around the world. From One Giant Step for Motorola 45 Years Ago: On 20 July 1969, our products transmitted a scene from the moon that was heard and seen by millions of people around the world: Neil ...


2

Motorola built the transponder on the LEM Collins built the S-band receivers for the DSN ground stations


2

I have a partial answer to your question. A few years back, I had a tour of the headphone company Plantronics and learned that they provided the headsets for the Apollo and Mercury programs. From the Wikipedia page on the company: The use of these SPENCOMM-NASA headsets in astronaut space suits continued through the remainder of the Mercury program, the ...


2

Cassini did this. Its high-gain antenna was used for both communications and radar. Some tradeoffs: time: if you want to use the same dish antenna for communications and radar, you need to divide the dish's use between both. Most interplanetary missions store their data and send it at intervals anyway (with 8 hours/day scheduled for communications), so ...


2

That was just for artistic purposes. The HGA was used for both uplink and downlink throughout both Pluto and MU69 encounters.


2

In this scenario, the last straw would be the hydrazine freezing which leads to loss of the thrusters. After a while, the loss of attitude control means Earth drifts out of view of the HGA. The impression I get from reading a lot about Voyager's systems in the last few days is that quite a large part of Voyager's power budget seems to be going towards ...


2

Both are used: low power for the 160 bps live telemetry: this is sent immediately, and not stored on board. This is done for at least 8 hours/day. high power for the high-speed tape playback. This is done 6 times a year for Voyager 1, Voyager 2 tape operations were ended in 2002. For Voyager 1, tape recorder operations will end in the next few years. ...


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