There-in is the big problem for us. Unless we wait for them to come to Earth and park themselves in orbit, we probably have no way of sending a probe to intercept them due to inertia. If we even knew where they would be at a specific point in time to intercept them, we can’t land or dock a probe as our probe is going in the opposite direction that they are, and are speeding along at an order of magnitude faster than bullets. We can’t carry enough propellant necessary to slow down and reverse direction unless we were lucky enough to swing around a planet to pair up with them if trajectories matched up. Once again, we’d need to know exactly where they were going to be a year + ahead of time. This leaves us with finding a way to send electromagnetic cues to them. @Matt_W - could we not clear a radio band and uncompress the stream to send basic messages?
Well, this is partly true. “Faster than bullets” has no meaning in space because almost all useful trajectories in space are generally far faster than bullets relative to the orbital focus. If the alien vessel was constantly altering its course, we’d have no chance of intercept because we’d be unable to predict its future position. That’s true. But if it was on a long elliptical trajectory, like in Rama, we’d be able to predict it and probably intercept. If it is going too fast to intercept, it’s not going to be able to use in-system gravity sources to alter its trajectory much. One of Rich’s assumptions was that it’s intended to eventually orbit Earth and that we know that. If that’s the case, we can intercept it inbound.
A note: the inbound object would be on a hyperbolic trajectory that bends around the Earth. We wouldn’t launch an intercept vessel directly back on its inbound trajectory–we’d launch it the other way into a long elliptical orbit that spins around and “catches up” to the alien vessel when the intercept vessel is heading back toward the Earth. The velocity difference probably wouldn’t be that extreme. Here’s a paper that discusses this kind of intercept.
Yeah, I suppose you could just transmit a sine wave with slowly varying amplitude or something. I still think that’s kind of a shot in the dark. Putting a pure sine wave on a clear band (how wide of a band?) would still look like noise to an indiscriminate receiver. We’d have to assume that they can filter down to a narrow band and are scanning up and down to see if they can find anything on a particular band. Maybe they are. It’s probably a good thing to try, but I don’t give it good odds of working. I think that anything that relies on technology is unlikely to work because technology is built on standards and common usage agreements. The lower tech, the better.
See I would operate under the assumption that if they entered the solar system on intercept for Earth, they can already detect us and can differentiate our EM transmissions from background noise.
Which is why I suggested them. Forget the encoding, don’t try high information density. Go with mathematical concepts, or simple mathematical representations of basic elemental chemistry, like a water molecule represented as the mathematical principle of the protons, neutrons, and electrons of the component atoms.
Worry about understanding after establishing communication. Establish that ‘someone is home’ first. Hence basic, non random, sequences.
And in @RichVR’s example, I am assuming that EM spectrum options have been exhausted. And we also need to know what speed they are moving at. All our communication methods (forget languages for now) take time to reach them. So we had better get multiple contingencies going at the same time. By the time we know that they aren’t responding to Light-based or Wave-based comms, it could be too late.
Exactly.
Right so…what speed are they moving at?
This is why I also suggest we complete the Aries III Interplanetary Craft ™ at all costs and arm it with nukes and get it launched.
Well then…
Wait for it orbit earth, and then send it one of the gold discs from Voyager. Just send up a probe containing the disk near them and gently tap on the surface to say hello .
Once they’ve read the disk they’ll know what to do and it’ll be all peace and happiness from here on out.
Look at how happy those alien fighter pilots are!
Nothing @RichVR has stated suggests hostility. If they were looking to make an interstellar bypass, they’d have done it.
We have no info on approach and speed. As well, to @CraigM’s point, we have to assume that, at a certain point, they are ignoring us. In any case, we must be prepared for all contingencies. Not just let them get here and give them a record.
Well, as long as it’s a Slim Whitman record we’ll be OK.
I was thinking this just to prove we aren’t pushovers…
An alien discovers coffee, and decides to invade earth using a creature capable of destroying planets (whose name is Herman) to secure the perfect coffee bean
I didn’t want to get into the mechanics so much. But okay. They are approaching Mars orbit, with enough speed to rendezvous with Earth in a three months. Assuming they don’t slow appreciably. Which they will certainly have to do, eventually.
We’re doomed. Screw your experiment. I am working on my Fallout shelter.
And previously stated that they were breaking via gravity, trajectory indicates earth orbit. So they’re in no particular hurry to get here. Sending out something with nukes is akin to a Neanderthal sharpening a spear to ward off a guided missile. But if it makes you feel better…
- send out a strong signal, something mathy™️
- get everyone else on the planet to shut up. Good luck.
- wait.
- ???
- profit.
Fools. They are here among us now! And we are already attempting (and failing miserably) at communication.
[Okay, at this point, I was going to go with Women, Cats, or Republicans. Cats seems like the safest bet, so I’m going with that.]