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As shown in the book/movie, each mission had its own gear capable of communicating with Earth, which seems redundant, yet still only be able to do so while the Earth is above the horizon.

However, why not have the first mission include a small constellation of communications satellites? That way, all later missions would only need much cheaper/lighter gear to reach a comsat, one of which would always be above the horizon and one of which would always be able to reach Earth.

In fact, the short-range gear to communicate with the comsats should be no more than a satphone, which means it should be light/cheap enough to put into every suit, rover, probe, etc. and have vastly increased capabilities and safety.

I know sending stuff to Mars isn't cheap, but if you are sending multiple manned missions, then the economics change dramatically. Putting long-range com gear in Mars orbit once seems a lot cheaper than safely landing it on the surface multiple times.

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    Because otherwise there would be no drama? – Rebel-Scum Mar 14 at 16:52
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    The book mentions that the MAV functions as a multi-spectrum transmitter with excellent bandwidth. They also have a ground-based radio with a big fat dish. Why would they need extra redundant satellites in orbit? – Valorum Mar 14 at 16:58
  • @Valorum Just to respond to you, and not the question, tying everything to the landing site (MAV, dish) severely limits the options for safely exploring outside line-of-sight. – DavidW Mar 14 at 17:19
  • @Valorum Putting all that heavy, expensive gear safely on the ground again for each mission is the redundancy, IMHO. – StephenS Mar 14 at 17:19
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    @StephenS - They never envisioned a situation where an astronaut would be on the ground without a MAV (Or rather, they imagined what would happen if the MAV exploded and then assumed that all the astronauts would die very very quickly afterwards from a lack of food, drinkable water and air and thus not need a way to communicate with Earth) – Valorum Mar 14 at 17:55
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Per the source novel, Mars has a veritable constellation of satellites in orbit, just none that are powerful enough to allow a useful two-way conversation between Mark's (now dishless) radio and NASA.

“Actually,” said Morris, “he’s got a radio, but he doesn’t have a dish.”

“Thing is,” Chuck continued, “without the dish, a signal would have to be really strong—”

“Like, melting-the-pigeons strong,” Morris supplied.

“—for him to get it,” Chuck finished.

“We considered Martian satellites,” Morris said. “They’re way closer. But the math doesn’t work out. Even SuperSurveyor 3, which has the strongest transmitter, would need to be fourteen times more powerful—”

Since the MAV missions were always intended to have their own powerful high-bandwidth radios that could communicate directly with Earth (plus no less than 3 backups that could also talk to the satellites), there was never a need for individual astronauts to carry wastefully heavy radios powerful enough to get signals into orbit.

“Yup,” Morris agreed. “The MAV is, like, a communicating machine. It can talk to Earth, Hermes, even satellites around Mars if it has to. And it has three independent systems to make sure nothing short of a meteor strike can stop communication.”

“Problem is,” Chuck said, “Commander Lewis and the rest of them took the MAV when they left.”

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  • Thanks, I forgot that exchange. An Earth satphone is under 1kg and can easily reach satellites at GEO, so this still makes no sense to me. I guess I'll just have to accept they didn't use the right radio tech for some reason. – StephenS Mar 14 at 18:47
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    @StephenS - Having your astronaurs tote around an entirely unneeded 1Kg of weight in their suit is practically criminal. – Valorum Mar 14 at 18:50
  • The Iridium 9555 is a mere 266g. How much is the radio to talk to the MAV? Probably similar since most of the mass will be battery, screen, case, etc. anyway; the radio and antenna themselves are negligible these days – StephenS Mar 14 at 19:04
  • @StephenS - Getting a pointless 266 gram radio to Mars (x 6) means that your space agency needs to spend an extra few million dollars on fuel, stowage, designs, etc. You also need to account for the extra calories needed by your astronauts to move them around as well as the hassle and dangers associated with extra electronics and more powerful battery, all for something that represents a contingency for nothing. Martian astronauts don't need to talk to satellites (well, until one does, but that's a whole book). – Valorum Mar 14 at 19:14
  • Can someone with more rep move this to chat? – StephenS Mar 14 at 19:21
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In real life Mars is surrounded by satellites designed to boost communication already, there are a number of satellites that have the ability to receive transmissions from the rovers on the surface of Mars and can then broadcast this to earth.

However this does not allow real time communication, at best messages take about 20 min to get from the rover to a satellite and then to earth. But to this time you have to add the time it takes for a satellite to orbit to a position that the mars rover can send it a message, and then if that is the side of mars furthest from earth it has to move into position to then broadcast to earth.

Now in regards to the Martian we know that there are satellites in orbit over the planet, we also know that they do not automatically allow full coverage of the planet. The fact that some of them have to be repositioned to be in the right place to see the ares landing base indicates that. Sending the kind of communications satellites for full 24hr coverage for a mission would be a massive waste of resources, time, money and effort. Considering that humans will be on mars for 20-30 days every few years then you have a host of satellites which have nothing else to do.

The universe of the Martian in based in realism right now NASA is planning a mars space mission and there are no plans to send a host of communication satellites ahead of that mission. But even if there where it wouldn’t help NASA deal real time with an issue as the best they could hope for was a message telling them there is a problem 20 minutes after it happened.

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