In real life, but more often in fiction, there are have been a number of examples of "Don't tell the crew" i.e. Mission control finding out about an issue and deciding that for whatever reason the crew should not be notified, even if the rest of the world knows.

For example in The Martian:

It's initially decided that the crew should not be told that Mark Watney is still alive on Mars.

In the case that the crew of the ISS are not told, but the rest of the world finds out, and NASA (and Roscosmos, ESA, JAXA, etc.) actively do not want them to find out, could someone unconnected to the astronauts (i.e. not hidden in a scheduled call or conversation) get a message to those on board?

Can you just broadcast a powerful enough radio signal, is there a required encoding, do the astronauts have uncontrolled internet access, etc.?


1 Answer 1


There are ham radios on the ISS, so it would be difficult or impossible to prevent the free exchange of information.

Some ISS crew members make random, unscheduled, amateur radio voice contacts with earth-bound radio amateurs, often called "hams". They can make radio contacts during their breaks, pre-sleep time and before and after mealtime. Astronauts have contacted thousands of hams around the world. The work schedules of the ISS crew dictate when they are able to operate the radios. The crew's usual waking period is 0730 - 1930 UTC. The most common times to find a crew member making casual periods are about one hour after waking and before sleeping, when they have personal time. They're usually free most of the weekend, as well.

Source: Contact the ISS

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    $\begingroup$ Ah excellent, thank you. Do you know if the ISS was the first station to have a ham radio? $\endgroup$
    – Freddie R
    Commented May 5, 2021 at 13:25
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    $\begingroup$ BTW, high power transmission (like a big commercial radio station of 50-100 kW) is not required to be received at ISS. Hams contact one another across the globe at distances greater than usually applies to contact with ISS. The ISS is only a few hundred to a few thousand kilometers away from any station site on Earth. Hams can contact other hams who are 10,000 to 15,000 km away if conditions are good. Some hams can even bounce pulses off of the Moon and receive the return signals.. $\endgroup$
    – Chris Ison
    Commented May 5, 2021 at 13:31
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    $\begingroup$ There was a ham radio on Mir. I don't know if that was the first or not. spacetoday.org/Satellites/Hamsats/Mir.html Shuttle too. space.stackexchange.com/q/49256/6944 $\endgroup$ Commented May 5, 2021 at 13:46
  • $\begingroup$ just asked in Ham SE: What was the first QSO by an astronaut? Was it code or voice? $\endgroup$
    – uhoh
    Commented Aug 10, 2023 at 6:44

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