So, there's a closed question So we have aliens in orbit. Now what? - but there's an implied assumption:

That somehow, there will be some unified / coherent response from humanity to aliens in orbit.

I find that extremely unlikely. People in mass, can't even keep their laser pointers to themselves, even when asked too and when it's clearly in everyone's benefit. There's always some yahoo out there who feels self-entitled enough to use his laser pointer to mess around.

Writ large on a planet with 7 billion people, and a fairly large first world population who have lasers, radios, model rockets, etc, etc.

Granted, most humans in current society will be unable to get to LEO or GEO, for a face-to-face meeting.

But, I see no way of keeping every religious cult, random nut-job, or yahoo from trying to contact aliens in orbit. And/or impersonating (or trying to) important people. I mean, you find an African-American actor and have him claim to be Obama (or for other movers and shakers: old Asian dude in glasses; or middle-aged Latin-American dude with a goatee), and put it on a tight-beam directed at the alien ship.

How would you have (in your story) a legitimate government / official-dom get their signal recognized from all of the chatter aimed at an alien ship? (or would you even bother? - Maybe you'd wait for them to contact you?)

Pouring more power into your signal seems like, screaming "I am the King!"... if you have to say it... well.

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    $\begingroup$ There's an implied assumption to this question. You're assuming that the aliens will know where, when and how to listen. An AM receiver can't be used to receive SSB, let alone FM or DAB. (Heck, a DVB-T receiver doesn't do DVB-C, for reasons that I fail to grasp.) And that's just a technology evolution over (in essence) a few decades here on Earth. What are the odds that the aliens would know to listen on a frequency and with a transmission mode on which we have the ready ability to transmit? $\endgroup$ – a CVn Mar 4 '15 at 10:42
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    $\begingroup$ Also, please don't change questions after they have received answers to add constraints on acceptable answers. If you wish to add constraints that invalidate existing answers, it is almost always better to ask a separate question. $\endgroup$ – a CVn Mar 4 '15 at 10:42
  • $\begingroup$ I've removed the edit, please ask it as a follow on question if you'd like but it invalidated the existing answers. $\endgroup$ – Tim B Mar 4 '15 at 12:08
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    $\begingroup$ Note that, when aliens pick a source to communicate with, that source will come under immediate scrutiny of all world powers. So, even if the aliens initially communicate with a nut-job, leading intelligence agencies with find out soon enough and take over the communications from the source in question. $\endgroup$ – Sanchises Mar 4 '15 at 12:36
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    $\begingroup$ @user3082 Unless your average nutjob comes with high-spec directional antennas (which may be true for rogue/terrorist states) AND you have intelligence agencies which do not direct all their resources towards the 'alien problem', somebody's going to find out sooner or later in my opinion. But of course, anything is possible. $\endgroup$ – Sanchises Mar 4 '15 at 17:14

Send the signal from the ISS.

The aliens should be well capable of detecting directionality of the signal, at least to a precision sufficient to distinguish Earth-based from LEO-based. And considering the ISS is one of the greatest scientific endeavors of Earth (easily observable), the crew can be trusted to behave in a responsible manner and forward the right messages.

Once public keys of 'authorized entities' of Earth, along with algorithms, have been passed from ISS, the communication can switch to direct channels, the signatures of the messages confirming authenticity.

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    $\begingroup$ So, 2 Americans, 2 Russians, and 2 EU'ers. Hmm, and we'll pretend no skullduggery or political shenanigans are planned... I'm contemplating changing my question, because your answer is so brilliant. :D If we didn't have an operational ISS, would you say any satellite? Or, what other answers would work. $\endgroup$ – user3082 Mar 4 '15 at 8:24
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    $\begingroup$ @user3082: Strength in numbers: the same message being sent from countless sources under authority of the 'authorized entity'; if it's being broadcast from 500 places all over the world, that surely outweighs one-off HAM radio enthusiasts, or even the might Kim Jong-un. Oh, the case would be much different in the times of the Cold War, and the aliens would probably need to make an important political decision... $\endgroup$ – SF. Mar 4 '15 at 8:41
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    $\begingroup$ Hmm, does that mean if the science-fiction community gets their [stuff] together, they're the most powerful entity around? They have people in every country, many of whom have resources (theirs, or under their control)... $\endgroup$ – user3082 Mar 4 '15 at 14:41
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    $\begingroup$ This answer is brilliant and elegant. It does rely on the assumption that the aliens recognize the significance of the ISS. "HAHA, remember when you sent your first signal from that solar powered scrap pile? Very funny! Oh Earth humor! What? That piece of junk is important to you? We thought it was a museum piece. Oh, I'm sure it's very nice. Pinnacle of your space program you say? Greatest achievement of Mankind? This is awkward." $\endgroup$ – Schwern Mar 4 '15 at 17:53
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    $\begingroup$ @Schwern well, it is the only space station, so it might have some obvious significance. That would be awkward, though... $\endgroup$ – k_g Apr 14 '15 at 4:53

VSauce has an interesting video where he talks about the two established, international organizations who are already set up to handle this, SETI and the UN Office for Outer Space Affairs.

While the UNOOSA denies having the authority to speak for Earth, if aliens show up the expectation is they'd be the ones everyone would look to coordinate our response. In a panic, governments like using established structures who have been thinking about the problem for a long time. The UNOOSA would look to SETI for help, who have been thinking about and waiting for this for a very long time. SETI has developed a plan "following the detection of extraterrestrial intelligence" which would likely form the framework for our official response. It includes...

  1. No response to a signal or other evidence of extraterrestrial intelligence should be sent until appropriate international consultations have taken place. The procedures for such consultations will be the subject of a separate agreement, declaration or arrangement.

Their official line is to keep quiet until we all talk about it. Assuming they agree, that would keep all of the major governments and institutions quiet (if they don't agree, then there is no legitimate official communications). That covers nearly everyone with access to a powerful, directional radio antenna. Maybe Earth will have to come up with the Intergalactic version of "please hold, your call is very important to us..."

What about rogue signals? Anything below a certain amount of power will be lost in the noise. What noise? Our noise. We emit a lot of electromagnetic noise into space. Some of it is chaotic, but a lot of it is patterned... communications. However, it is all patterned differently as we use dozens and dozens of different protocols. Ironically, some of our most important communications will look like random noise because they are encrypted. The aliens will have been observing this for some time as they approach. If they do not understand the content, they will understand that it is intelligent. However, the overall pattern will be chaotic from many sources and in many forms.

Whether or not they will recognize this means we are not unified is speculation, but they will recognize that random electromagnetic chatter is normal. Having some yahoo bounce the digits of Pi off their ship with a relatively low power laser isn't likely to seem out of the ordinary.

Nor are they likely to communicate anything intelligible to the aliens beyond basic math, not before the rest of the Earth gets its act together. We don't know what part of the electromagnetic spectrum they're observing, how they're using it (AM or FM or something else?), or if they're even using electromagnetism at all! If they knew how to finely manipulate gravity waves how we manipulate EM we could be staring dumbly at each other for a while.

The only rogue nation with a space program capable of powerful communications is North Korea (Iran could probably do it, but they're not as rogue as the US paints them to be) who would be the wild card. However we're safe in that North Korean scientists are not going to crack the code before everyone else does. We're double safe in that the messages will likely be internally politically focused narcissistic gibberish. "Here is a JPEG of our Dear Leader!"

When Earth responds, they must do something out of the ordinary to get noticed. They must order the chaos, that's a clear sign of intelligence. Individual governments and institutions, guided by the UN on the advice of SETI, would all point their transmitters at the alien ship and simultaneously broadcast the same message. This is unprecedented in the history of humanity. One group transmitting with the most power is like shouting "LISTEN TO ME, I AM THE LOUDEST", but having multiple sources all over the planet sending the same signal says

Listen to us, our voice is unified.


It seems to me that the aliens would have access to our broadcasts, and be able to monitor our television and radio not just after they arrive but while they are approaching. Sufficiently advanced computing technology would have translation software working by the time they reached orbit.

Once in orbit they can also try and piggy back into the Internet by reverse engineering the protocols and intercepting some satellite up-links.

Between these two sources of information it shouldn't take them long to understand our political makeup and work out who would be appropriate to contact depending on their long term goals.

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    $\begingroup$ ...and it'll allow them to watch cute kitten videos while they are working on it and waiting for a response. Double win! $\endgroup$ – a CVn Mar 4 '15 at 12:12
  • $\begingroup$ So your answer boils down to: wait for them to contact our glorious leader, correct? $\endgroup$ – user3082 Mar 4 '15 at 14:39
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    $\begingroup$ @user3082 Or to use the knowledge they have gathered to choose which communications to respond to. $\endgroup$ – Tim B Mar 4 '15 at 14:42

Who can speak on behalf of Earth? I know I am posting "non-answer" but I still have to:

We have United Nations which could be the closest to "Earth representation" as we can get. But I doubt that UN has technology to communicate to space. And getting this huge organisation into agreement what should be done can take too long. So, sadly, we have to put them out of equation and ask differently:

Who has power to communicate? Simply put, anyone. Leading powers would have some upper hand and for simplicity, lets put these powers in mind: India, USA, Europe, China and even North Korea.

And it gets worse: Big media houses. They have commercial satellites and they would sell their moms for possibility to broadcast alien communication on live TV. Imagine the prices for advertisement! Huge profit!

Who has power to take aliens down? USA, China, Russia, India and even North Korea. Hope I did not miss anyone important. Good luck having them all agree to not shoot on the aliens. Especially if aliens look ugly and dangerous

Sadly, your question has only one plausible solution:

What do aliens know about us? What is their motivation?

Did they come in person, because we did not get their response in first place? Are we interesting insect to investigate further? Is our planet valuable resource for them?

Several ideas:

Comedy/Parody: For whatever reason, the aliens could catch only North Korea state TV broadcast. They come to see glorious leader Kim Jong-Un to salute him in his awesomeness. Boil down the story in several misunderstandings.

Drama Earth is valuable resource. They have no motive in talking to us in first place. They came to kill us all.

Sci-fi It is simple "first contract". From story perspective, it would be interesting to make aliens believe that your country represents Earth as whole and your "leader" is the one with power to represent the whole Earth. Spend some time into investigating, what other countries might think and do.

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    $\begingroup$ I don't agree that North Korea has the power to take aliens down. $\endgroup$ – gerrit Mar 4 '15 at 15:46
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    $\begingroup$ @gerrit I don't agree that any world power necessarily would be able to take the aliens down $\endgroup$ – Michael Mar 4 '15 at 16:33
  • $\begingroup$ It all depends on the abilities and behaviour of the aliens. If they fly in a low predictable orbit that passes near North Korea, I would not be surprised if they could place a nuke in their path. The ship would be moving faster than the missile, but predictable = dead. A higher orbit and proper missile/meteor defense means that nobody could touch them. $\endgroup$ – Stig Hemmer Sep 30 '15 at 10:37

The usual method to guarantee the identify of the source of a message is cryptography and it's related areas. All correct answers will revolve around this.

The three pillars of information security are :

Confidentiality : Guarantee that only those who are entitled to read the messages are able to do so. Reliability : Guarantee that the message will be delivered when needed. Identity : Guarantee that those which the message identify as authors are trully the authors of the message.

So, it follows on from information security practice, that the most usual way to guarantee those pillars are those methods based on cryptography.

By, for one, encrypting each message with a public key cryptography method, you can guarantee (to a large degree) that the message was sent by the authorities that hold the valid key.

The only final problem is key distribution. Aliens would need to exchange keys with earth's authorities in order to allow the identification of the message sources. This would, probably involve landing a spacecraft in front of the white house, just like in the movies.

Another, less guaranteed way to deliver the message with some security about its sender, is to have your largest most powerfull transmiter point to space and send it. This is brute force, because, probably, your competitors (those wanting to send messages as if they were true authorities) would probably have less money to engenieer powerfull transmitters. But, in a multipolar world like ours, nothing prevents other national entities, besides USA, to build such transmitters and start to talking to the aliens, as if they where the USA, or vice versa. This might have political consequences that are out of the scope of this answer.


I think Tim B's answer pretty well covers it, but I would assume that most governments, particularly super powers, like the US and China, would make an effort to employ radio jamming and other signal disruption in order to try and dominate the conversation.

While the aliens may have decided that they would rather make contact with a particular government, some governments may attempt to hijack the conversation by deploying large scale jamming efforts. For instance if the aliens decided to contact China the US may decide that that is unacceptable and try to block their signal or vice versa...

It would also be pretty likely that many governments would try to eliminate chatter by scrambling/jamming non-official signals within their own borders.

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    $\begingroup$ You can't jam a focused, directional signal without also silencing yourself. $\endgroup$ – Schwern Mar 4 '15 at 17:49
  • $\begingroup$ @Schwern But they would only need to jam until governments and such figured out what they want to say. $\endgroup$ – AJMansfield Mar 4 '15 at 23:16
  • $\begingroup$ @AJMansfield Yes, which could take a few days. Meanwhile you're screaming gibberish at the aliens. Probably confusing and not very friendly. Once you drop your jamming to talk the aliens can hear everyone else clearly again so you're back to square one. The point is, signal jamming isn't the flip of a switch we see in the movies. $\endgroup$ – Schwern Mar 4 '15 at 23:29

If human presence in space has progressed, they would study the behavior and see how Traffic Control / Port Authority is handled. It would be very rude to have a plasma exhaust cross a shipping lane, and they would need to learn a little about how things work.

The legitimate authority is whom everyone else is taking orders from and coordinating through. If the contactor says "we'll send a pilot to guide you through the inner system" and one of the ships shows up as planned, that's a good sign.


Aliens wouldn't just tune into their radio to hear what our leader is saying. They would stay in orbit a while, maybe dodging a couple missiles (on Earth, humans studying animals aren't too off put by being attacked. Aliens could reasonably stay in orbit even if we provoke.) They would wait a long while, figure out our social structure, and then maybe try to communicate with multiple leaders.

This is all assuming the aliens are advanced enough to actually form any sort of relationship with Earth. It could simply be a probe or something, not even capable of landing. In that case, it doesn't need to know who is boss.


In my story, I'd probably have the aliens have studied Earth broadcast media for a while, and figured us all out fairly well, at least as far as being able to understand something about our government organizations. And they'd probably want to engineer a big change to those baroque and corrupted systems. They'd probably use our government structures to identify the corrupting elements, and eliminate/dismiss/correct those one way or another, and start up their own new government structures for the earth, and detain and re-educate the corrupt when they showed up to that.

In fact, the first government would probably mostly be made up of non-human Earthlings. Whales, orang-utans, giant sequoias, fungus, bee queens, elephants, octopi, ravens, etc. After all, clearly a LOT of affirmative action is in order!


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