Mars has been colonized, close to a million people are now living above (and below) the martian soil, every few months a ship from Earth arrives with more resource for expansion and more settlers, currently the travel is one way until the martian space elevator will be completed in the near future.

Everything is going well until one day the "blackout" happens, all communication to Earth & the sister colonies on the moon stopped, pointing what telescopes the Martian settlers did have to Earth show no signs of life - no lights in the dark sides of the planet, no signals of any kind in any of the electric spectrum that the settlers have equipment to measure and as the months pass no new ships arrive.

It's as if one day everybody on Earth and Earth orbit just vanished.

The Question

What caused the "blackout"?

  • The settlers don't know if anyone is alive, causes which would keep people alive on Earth yet unable to communicate with Mars or use anything that shows sign of life to settlers outside the planet is acceptable.
  • Ideally Earth should remain intact, I would prefer answers where the settlers are guessing but never know for sure what happened on Earth.
  • Tech level is near future - 100 years to the future is a good benchmark.
  • Whatever the "blackout" is it should have no affect on Mars.
  • I can handwave the lunar colonies using Earth to relay communication with Mars do to the small size of the lunar colony so it's possible the "blackout" to affect Earth only and not the moon - however satellites around the earth should still be affected as even automatic transmissions from them stopped.
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    Changed the locks after unwelcome boarders left... nothing to see here. Just pretend you're not at home if they come calling – nzaman Oct 13 at 12:34
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    Is Mars continuously observing Earth? Or does it only look at Earth occasionally? – Jasper Oct 13 at 14:00
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    The way I imagine it is that before the blackout there was non stop data transfer between Earth and mars, a million people sending messages to their loved ones, scientfic data, even new movies all flow from one planet to the other non stop... I assume that after the blackout happen there will be someone on mars trying non stop to reconnect back with earth on but it's possible that due to lack of resources there are time gaps where Mars can't observe Earth at all. – cypher Oct 13 at 14:16
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    You're asking what a high concept question. You have a plot-critical event and you're asking us to rationalize it. On the one hand, these questions are susceptible to being primarily opinion-based. On the other hand, the question is susceptible to being too story-based. You need to ensure this question is about a rule of your world, not an event in your world, and provide criteria for a best answer. – JBH Oct 13 at 20:32
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    @DonQuiKong, per my comment, "you need to ensure this question is about a rule of your world, not an event in your world, and provide cirteria for a best answer." I note that neither has happened. – JBH Oct 14 at 13:21

13 Answers 13

A massive solar flare was emitted by the sun and engulfed both earth and the moon but mars was no-where near that part of the solar system. The flare was extremely powerful, far more so than any on record, and basically destroyed all electronic devices. Those people who survived the immediate aftermath as everything moving crashed and all life support, navigation, communications etc fried in an instant are too busy with rescue and recovery efforts to even think about mars.

Anyone in space is most likely dying of radiation poisoning even if their life support systems can be recovered (although more heavily shielded areas may offer some protection).

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    Since the author of the question does not need a full extinction level event, a solar flare could just burn every radio emitter on earth, meaning it could take weeks or even months to get communications to work again. – kikirex Oct 13 at 17:18
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    @kikirex Yep, most people in orbit/flying would die but people on the ground would not be killed directly. There would be a lot of shortages of supplies though as civilization basically collapsed overnight and depending on the severity of the damage months, years, or even longer to recover. – Tim B Oct 13 at 17:25
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    The beauty of this though is you can make it as devastating or not as the plot requires. – Tim B Oct 13 at 17:25
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    @kikirex If you fry every radio you did an awful lot of damage. Earth's supply chains have been seriously disrupted. Expect major violence as people fight over the supplies that are local because things aren't coming in anymore. You'll likely punch so many holes in civilization that it crashes--and that could easily be an extinction event. – Loren Pechtel Oct 14 at 2:05
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    @DisplayName Have the flare last over 12 hours or occur twice to cover the whole globe. A plot feature can have some NASA radio amateurs re-establish sporadic contact with Mars a few years later with a big dish and some thermionic valve radio gear and manual dish steering and apologise for the break in programming. – KalleMP Oct 14 at 19:33

The origins of this mystery dates back to early 2000's. The small SETI office in the Hat Creek Observatory was filled with the noise of computers beeping and buzzing.

They had just detected an alien transmission and were repeatedly receiving the same transmission for about an hour now. Language Experts and scientists were flown in early in the morning at 2:35 AM to assess the transmission and find out what they meant and who were transmitting them.

After a day of analysis, the scientists narrowed down the origin of these signals to a star "GJ 3059", about 70 Light-years from the Earth.

A week later, the Language Experts produced their final draft:

"Beware! A large group of Dangerous Intelligent Machines are coming towards your planet. They will destroy all the life on your planet to make it suitable for an alien species. The only way to protect your planet is to create another planet near-by with life and Radio Transmission and stop radio transmission and artificial lights on your planet. There is roughly 170 Earth-years before these machines reach you. You must go radio-silent within 140 years to hide your exact location."

The major leaders of the most powerful nations had a confidencial meeting and decided to maintain this as a Top Secret and signed an agreement to dedicate significant resources in creating a decoy planet.

Major corporations were funded to develop technologies required to colonise Mars. Venus was supposed to be the plan-B. A team of PR experts were appointed to suppress public opinions against funding space travel.

On Day-Zero, the world-leaders announced that there have been major solar flares and all of the communication satellites and major radio communication devices have been destroyed. And more solar flares are expected in the near future. So, all communication will be switched to Optic-fibers and low-range transmissions only for a few years. Almost all artificial lightings and electric grids have also been destroyed. Electricity will only be supplied during the day and do not step out of your homes, after sunset. They filled the Online news with reports of people being affected by these solar-flares and increasing incidents of associated Radiation poisoning and various types of cancers. Videos of the sun emitting bursts of plasma into the space were spread like wild-fire. All this was closely orchestrated and executed by a planning committee of experts, who were planning this for over 50 years.

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    I am not sure about the last paragraph, but I do like the idea of the plot twist. – Matthieu M. Oct 14 at 21:23
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    Another twist that would quite plausibly happen later: the message was actually mistranslated. This wasn't a warning by some third party, recommending to plant a decoy, it was just a bulldozer announcement by the invaders themselves. They were going to target Earth anyway, and just urged humans to move out or be erased on Earth. As this becomes clear, the people of Earth frantically start to re-establish contact to Mars and move there, but aren't trusted anymore, prompting a large-scale war between the two planets before the aliens ever arrive. – leftaroundabout Oct 15 at 10:25
  • I thought a global catastrophic event would be too obviously visible from Mars. Even solar flares WILL reach Mars, due to its lower magnetic fields and thinner atmosphere. Also, somebody on the Other side of the Earth would have communicated about the event to somebody on Mars. – Rakesh Gopal Oct 15 at 13:35

It was the Singularity. The density of computer networks and AIs on Earth reached a critical point, and humanity and its machines abruptly ascended into something unknowable. See Vernor Vinge’s novel Marooned In Realtime for a version of this idea where the separation is in time rather than in space.

  • But why would the newborn global AI not want to talk to their parents' friends back on Mars? – John Dvorak Oct 15 at 12:48
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    @JohnDvorak It’s so far beyond us that we can’t begin to speculate about its motivations. – Mike Scott Oct 15 at 13:00

Look for "The Locusts" by Larry Niven and Steven Barnes. First published in Analog in 1979. Colonists land on foreign planet (in story, around a new star). They settle in and eventually start having kids. But the kids are a bit, well, stupid. And the second generation isn’t really sentient. The grandparents are in full scale panic. Why? Well turns out, humans are like locusts... when our numbers swell, our genome metastasizes to create a massive brain which causes us to be spacefaring, but having completed our spawning, we revert to feral form for another few thousand years.

That was 1979. Since then, we’ve discovered many species where even adult members of the population shift body types, even gender, in response to environment concerns such as population pressure. As soon as humanity “spawns” onto another world, there’s a global collective sigh of relief that all our eggs aren’t in one basket. Earth is a paradise of resources without environmental threat to the species, and we’ve just solved our last species-wide biological mandate. That tension release triggers hormones and unwinds our intelligence. Mars colonists ate unaffected because they’re still experiencing the survival stress of a new world.

Doesn’t solve the satellite problem unless, as intellect declines, someone does something stupid, like turn them off or crash a couple into each other and create a cascade crash.

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    By the OP, about one million people has left Earth. This effect could affect the people on Mars, but not the several billions still on Earth. – SJuan76 Oct 13 at 15:51
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    +1 for the idea that it's the fact that mars is the root cause - that's quite a twist, but unfortunately I'm not going to mark it as the answer as I'm looking for something a bit more realistic – cypher Oct 13 at 16:25
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    @SJuan76 It doesn't happen immediately. Once Mars is established enough, children on Earth start being born reverted. After enough time, no one can sustain contact. Mars would know about it ahead of time, though. – jaxad0127 Oct 14 at 0:09
  • @jaxad0127 there are some species we’ve found where it happens almost immediately in adults. Never in mammals, so far as I know, but we cannot rule it out until we understand what all our genes do. We don’t know what genes control our intelligence, so we cannot know for sure. – SRM Oct 14 at 7:13

Coordinated EMP Terrorist attack

A small but powerful fringe terrorist group managed to get their hands on half a dozen nuclear weapons. To maximize impact they simultaneously detonate the nukes at high altitude so that they cover all human habitats, plunging the world into darkness from the EMP pulse.

A few details on the Moon, Mars' observation and miscellaneous items:

  • The moon is far enough away that the EMP shockwave may be mild or non-existent. A separate nuke may have been sent its way but it's possible that the moon colonists' equipment are somewhat hardened against EMP (as precaution from solar flares).
  • If Martian Telescopes are not constantly aimed at the earth, then the blasts themselves would be missed by the martians. However, there would probably be radio noise during the event that was recorded.
  • Present day military should probably possess "EMP Hardened" equipment that would survive such events (natural or man-made) and would be able to contact Mars not long after the incident. Perhaps they are too busy dealing with the chaos and social upheaval on earth.
  • This is my first post (!!) please go easy on me! ;)


I'm adding a bit of speculation backed by factual information:

  • I really do believe that less than half a dozen nukes would be enough to make the earth go dark. If powerful enough, perhaps two nukes might be enough to cover both hemispheres. But that's just my own personal guess.
  • By looking at the image included in the link provided above, one can see from a 400km altitude detonation an area of effect that covers nearly the entire continental US and Canada. I'm guessing the radius of that circle to be about 1,000 miles. (The SVG version has a clearer circle. Sorry for mixing metric and english ;) ) The image makes no mention of the blast yield.
  • Actual high altitude tests were conducted in the 60s. The best known was Starfish Prime in 1962. According to Wikipedia, this was a 1.4 Megaton warhead that was detonated at an altitude of 400km approximately 900 miles away from Hawaii. To quote wikipedia:

The Starfish Prime electromagnetic pulse also made those effects known to the public by causing electrical damage in Hawaii, about 1,445 kilometres (898 mi) away from the detonation point, knocking out about 300 streetlights, setting off numerous burglar alarms and damaging a telephone company microwave link. The EMP damage to the microwave link shut down telephone calls from Kauai to the other Hawaiian islands.

Further down the article, the fate of some satellites is described:

The weaponeers became quite worried when three satellites in low Earth orbit were disabled. The half-life of the energetic electrons was only a few days. At the time it was not known that solar and cosmic particle fluxes varied by a factor 10, and energies could exceed 1 MeV. In the months that followed these man-made radiation belts eventually caused six or more satellites to fail, as radiation damaged their solar arrays or electronics, including the first commercial relay communication satellite, Telstar, as well as the United Kingdom's first satellite, Ariel 1. Detectors on Telstar, TRAAC, Injun, and Ariel 1 were used to measure distribution of the radiation produced by the tests.

  • This may not sound like much but keep in mind that this is 1962, long before everything became computerized and that Hawaii was probably near the furthest edge of the area of effect of the blast. Browsing through a list of US nuclear tests I found Castle Bravo with a yield of 15 Megatons and topping that is the Soviet Tsar Bomba which managed to produce a yield of 50 Megatons. I would imagine that by simply altering the denotation altitude and blast yield the radius of the affected region can be greatly increased!

To summarize, I really do believe that only a handful of nukes would suffice for this scenario.

  • Nice idea, I doubt that a few hundred such detonations would knock out enough of the earth's infrastructure to put the lights out. The major cities perhaps but not all the satellites or deep space relay sites all in one go. That is unless the nukes were used to destroy the deep space relay system because it was a religious abomination. – KalleMP Oct 14 at 19:37
  • Thank you! I really do think that a handful of nukes is enough, so I edited my answer with more detailed information extracted from Wikipedia. I also mentioned some effects on satellites as well. Even a single blast is enough to make the continental US go dark and this, in fact, is part of the backstory to Jessica Alba's Dark Angel series! – stux Oct 18 at 2:10

Everything has died.

The SCP site has a couple of entries about things like this. A signal is received that seems to be coming from a cave. On exiting the far side of the cave, the explorers enter into a parallel world - the same as ours, but everything has died. Warning: if you are like me, reading on the SCP site can send you down a rabbit hole it will take you hours to escape.

The SCP-2935 anomaly is a nearly exact replicate reality of modern Earth in the year 2016, with the primary exception being that all life, including both biological and non-biological, as well as any sentient entities, machines, computers and other "life-like" phenomena, within SCP-2935 ended on April 20th, 2016.

Juno: Command, you can see this?

Command: We can. Can you confirm life signs on any of those individuals?

Juno: I can… the adult male is dead… and the female to his right… and to his left… and the child… also dead. This had to be pretty recent, no signs of decomp.

Kael: This is pretty fucked up.

Devon: There's a newspaper on the table. April 19th, 2016. Hendricks County Flyer. Command, can you confirm the headline?

Command: One moment, Team.

Kael: Dinner, look. Chicken, mashed potatoes, green beans.

Command: Confirming that headline. It's accurate with that newspaper on that date.

Kael: It's stale, but there's no—

Devon: Wall clock says the date is April 28th, 2016. That's today. Same time, too, 0945. Same as my time. How long have they been here?

Kael: Boss, look. The food.

Juno: What about it?

Kael: It's covered in dust. They— they are too. They've been here for a while. But the food, it's all stale, but it's not rotten. That chicken should've been covered in mold by now, but there's nothing. See? Even the potatoes.

Juno: Yeah, I see it.

1.) An alien virus received through the SETI system mentioned above that worked like an EMP that cooked everything that had a microchip on it.

2.) Earth had actually died off centuries ago , but the mars inhabitants were given a universal fake memory of earth actually being there a day ago.

3.) Mars has been infected with some kind of computer virus , earth purposely quarantines all communication to avoid being infected

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    I want to vote this up but only for answer #2. Numbers 1 & 3... computers just don’t work like that. – SRM Oct 14 at 22:39

The authorities on earth see something very big coming up behind Mars (out of sight of the folks on Mars). They are unsure if this is a weird giant space beast, or an invasion force or a religious event. Its traveling toward a transmitter on an outpost, so whatever it is, it seems to tracks radio waves. It is unknown if the "something" has noticed that earth is populated, so until there is clear understanding of the risk, Earth has halting all transmissions that could give away its position or clear proof that it is inhabited or give this thing an incentive to visit.

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    Welcome to Worldbuilding! This answer is definitely inventive -- good out of box idea. Problem: how do you convince everyone on Earth to stop talking? The US Navy can't even get one ship of sailors to keep cell phones off during training ops. How do we get everyone to agree to stop transmitting? – SRM Oct 14 at 19:32
  • @SRM: Does it matter if cell phones are off, when the cell towers are? Corporations will abide with governments mandate much more easily than individuals, and they have the powerful emitters. Likewise, power cuts can easily be coordinated at night and a few odd light bulbs probably won't matter. Mars can be pretty far from Earth, so maybe shutting down the bulk of communications/light is sufficient? – Matthieu M. Oct 14 at 21:28
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    @Matthieu But will the US govt actually get over lobbyist objections (“You’re overreacting...”) to turn off companies? Will the US shut down if only China’s deep space probe has detected the thing? Even if all the space faring nations flag the thing, will all the small countries voluntarily go along? Will there be a rogue failed state that uses this as the ultimate terrorist weapon? To me, getting that kind of global cooperation even in the face of extinction stretches believability too far. But maybe you can spin the tale plausibly. – SRM Oct 14 at 22:36

Time travel.

When I read this:

pointing what telescopes the Martian settlers did have to Earth show no signs of life - no lights in the dark sides of the planet, no signals of any kind in any of the electric spectrum that the settlers have equipment to measure and as the months pass no new ships arrive.

I immediately thought: This is consistent with Mars being suddenly and unceremoniously dumped some hundreds or thousands of years into the past. The Earth of that time wouldn't have any kind of electronic technology or mass lighting infrastructure, so of course the Martian settlers wouldn't be able to see any light or EM spectrum signals coming from Earth.

Something similar happens in Time Odyssey. In this story, aliens™ grab a whole bunch of slices of Earth from various time periods throughout history (including a UN peacekeeper helicopter from 2037, a Soyuz space capsule from 2037, a British fort from 1885, 19th-century Chicago, the Mongol Empire during the reign of Genghis Khan, and the army of Alexander the Great) and stitch the slices together into a patchworld Earth in a pocket universe.

In a later book, they find out that Mars has been similarly patchworlded, and there's a whole plot thread where they have to send a message from patchworld Earth to patchworld Mars using only 19th century technology. (They dig vast trenches in the North American icecap, fill them with oil, and set them ablaze; the sole remaining inhabitant of patchworld Mars observes the pattern).

Kessler Syndrome

No one needs to die, no fancy scenarios. We. just. got. greedy. In the race to put more and more satellites up there, we put so many in orbit (while not cleaning up) that the Kessler syndrome was inevitable, wiping out all communication (or otherwise) satellites. Quoting wikipedia:

Kesseler Syndrome [..] is a scenario in which the density of objects in low earth orbit (LEO) is high enough that collisions between objects could cause a cascade where each collision generates space debris that increases the likelihood of further collisions

The Envisat is already a large, inactive satellite, that will stay there for ~150 more years and is a good candidate for such a catastrophe.

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    I actually wanted to write that aswell, as it is very likely to happend someday. But as cyper stated, after the incident the people from Mars couldnt detect any activität from earth, not even lights on the dark side. So either the Kessler Syndrom starts something devestating (Nuclear War, Rebelions), or someone started something like that by inducing the Kessler-Syndrom (destroy communication, destabilize society) by destroying certain important satellites. – PSquall Oct 15 at 12:53

Supermassive blackholes, such as those found at the center of galaxies, produce relativistic jets of particles from their poles. ( ). Such jets can exceed millions of parsecs in length. Because the cone of these jets is so narrow, it is kind of like a laser fired across space. But the radiation in these is lethal. If one of these jets from some other galaxy happened by random chance to sweep through, it could pick off one side of solar orbit without affecting the other side. There would be little hint that Sol was about to cross such a stream (just as you cannot see a laser until it hits something). The crossing could happen quite quickly if we went through the edge of a jet. If Mars was on opposite side of Sol while Earth gets cooked, Mars wouldn’t see the cooking. When the planets came back on the same side, Earth, and other planets that were over there, would just be an irradiated mess. Silent and black, including satellites.

  • That would cook one side of the Earth, but the other side would be shielded by thousands of miles of rock and metal. – Mike Scott Oct 13 at 15:26
  • No. It would encompass the planet by combination of atmospheric scattering and solar reflection. @MikeScott – SRM Oct 13 at 15:31
  • And that’s if the beam came straight in on our pole. If it came in at all at an angle, Earth’s rotation would cook all sides evenly. – SRM Oct 13 at 15:33
  • It wouldn’t cook the Earth fast enough to prevent the news from getting to Mars. There’s non-stop data transfer between Earth and Mars, so whatever happens has to affect the whole Earth simultaneously. – Mike Scott Oct 13 at 15:57
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    Another problem: jets are not so narrow, their width is a couple percent of their length (source), so even one from the nearest star would have width many times the radius of the solar system. We also can't argue Earth is hit by an edge of the jet, since the edge is not clear-cut - if it's enough to scorch Earth, Mars will feel it to – Wojowu Oct 13 at 16:21

Total financial collapse on Earth, Mars has cost Earth more than it could actually afford in terms of physical resources, the powers that be have always known what was going to happen but they pushed on regardless, Earth was no longer ecologically stable enough to guarantee our survival as a species.

The blackout is because the economy has finally caught up with the material resource reality and the planetary transportation web has fallen over in the space of a week or two. Most urbanites will starve within a week or two and take down huge areas of country side around the major cites as well. To survive people will have to be lucky and far away from "civilisation"; it's not that Earth is dead or even that it's technological artifacts, like satellites, have gone but there's no-one left in the areas where control apparatus are situated to use that equipment.

Any colony that is dependent on Earth for supplies, either technical (like solar storm warnings) or material, (food, water, and/or fuel), like Lunar, will also collapse pretty quickly as shipments suddenly and unexpectedly come to a halt.

I think people have covered the scenarios in which technology on Earth is greatly reduced, or civilization is entirely wiped out. To try and fit with your desire to have civilization still exist on Earth, I propose a third option. At this point in history there will be many crowded orbits around Earth. Even though space debris removal may be common, a Kessler Syndrome scenario could still occur and block communications with Mars in two ways.

  1. All deep space communications have moved to orbital relays to avoid atmospheric interference. Currently the Deep Space Network is ground-based, but if the relays were all in space and subsequently destroyed communications would be down for a time. How long would depend on how quickly Earth civilization can fix their orbital crisis and get new relays up or rebuild/reopen the ground stations.
  2. Some massive space engineering project was underway and the materials or partially built structures have been destroyed and spread across broad orbits. This entirely blocks radio transmissions - at least in the direction of the ecliptic. The solution to this scenario is much the same as the first.
  • While a cool idea how would that prevent Mars based telescopes see signs of human life on earth? – cypher Oct 25 at 10:40
  • So to my understanding it is really hard to see fine details on the surface of another planet without actually going there. Here ( is a view of Mars through Hubble. So this is our best space-based optical telescope at its closest to Mars and though it's a great image it's not exactly showing fine detail. From this image I doubt I could discern any human activity on the surface visually, and I would presume that the reverse situation of looking at Earth from Mars (assuming they even have space-based telescopes) is true as well. – ben Oct 25 at 18:21

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