Wikipedia to the Moon
meta.wikimedia.org
meta.wikimedia.org
Especially if they have decent midrange sensors to display nearby craft, Earth will look like a swarm of bees. Run any orbital debris simulator if you don't believe me. It's a mess up there.
> Orbits tend to decay over time, at a rate determined by the initial altitude. Anything above 2,000 km will take millennia to return to Earth, while satellites further down might take centuries or decades.
http://www.slate.com/articles/news_and_politics/explainer/20...
Distant orbits might decay away from Earth given enough time and certain circumstances, oddly enough. A return to Earth is not guaranteed.
(Or they're just being nice to me...)
But the other answer is that it's much easier to find. Where would you put a ceramic copy of wikipedia on Earth to maximize it's probability of being found? Anywhere you put it could get destroyed, buried, or stolen. Who knows what will happen to it over the Eons.
This disc will be on the surface of the moon forever. Anyone surveying the surface of the moon for unnatural objects will find it. Although that might take some advanced technology, it would be easier than surveying the Earth.
And while they might find many artifacts on Earth, locating that single copy of wikipedia out of all the other junk we've left behind is a bit improbable. We haven't covered the moon with much junk.
Or until a meteorite hits it.
Is that the dark part of the light side, where the sun won't overexpose the video?
Flashes from bolide strikes are actually easier to see on that part of the Moon where it's night. Where the Sun is above horizon on the Moon, the ambient light is drowning out any light-producing events.
If you read the FAQ[1], it says:
> [aliens] Probably not … but well, who knows? No, the Lunar challenge is mainly about pioneer spirit, curiosity, and visions for humanity. So, with the symbolic act of leaving a snapshot of human history on the surface of the Moon, we are thinking more about future generations than aliens.
And past civilizations at least seemed to have cared much more about longevity of their creations than we do, we can not even store our digital photos reliably over a decade without active replication. Without projects like this, future researchers will have to put the whole picture together using only plastic bottles and broken vinyl records :)
As for preserving things for future generations, I don't know of any good storage techniques. The problem with M-DISCs and other mad-high-density digital storage is that the readers will (most likely) be completely unavailable long before the all of the discs have degraded.
Perhaps we should engrave our data in 2D barcodes, alongside some readable instructions describing how the data can be decoded... Wouldn't have anywhere near the density of optical, magnetic or flash storage though. The whole situation does "worry" me a little, I agree entirely about future researchers not having much to go on.
Delta-V = Exhaust velocity x natural log(mass full / mass empty).
As the "mass empty" is very dependent on the payload size, it will indeed change a lot!
Another interesting read in this aspect is the Dawn Spacecraft, which had a big delta-v because of its ionic thrusters: https://en.wikipedia.org/wiki/Dawn_%28spacecraft%29#Propulsi...
At least that's what the FAQ says [0]:
> [Part-Time Scientists] will join a commercial space flight, e. g. a rocket launch to orbit. From there, their own lunar lander module will travel to the Moon, the final task being to land safely and release the rover.
[0] https://meta.m.wikimedia.org/wiki/Wikipedia_to_the_Moon/FAQ#...
2 200GB MicroSDs would give you 400GB of storage weighing in at only 1 gram.
> Can’t we use some other medium with more space?
> The conditions in space prove hostile to many data mediums. Traditional CDs or DVDs would be destroyed in space, because they are composed of layers and would come undone. It’s different with a medium made of ceramics. Also, you have to consider the dimensions and weight of your medium. The ceramic disc is light enough and resilient.
I'm guessing microSD cards are not radiation hardened.
That being said no one is sure how often it gets hit but it is logically far far less than Earth.
Wikipedia is missing some material though. A better choice might be the google book project or libgen, which contains a ton of obscure books and scientific papers. But compressing it all to 20 GB would be difficult or impossible. Much easier than compressing Youtube though.
That's more than anyone ever needs to know about Kim Kardashian.
Admittedly, with YouTube they might get the idea that humans communicate with each other mainly via the medium of song and that cats are sacred, but at least they'd learn something
Any civilization capable of retrieving the disk should understand enough about information theory to undo compression. Instructions can also be explained in detail with pictures at the beginning, uncompressed.
There's a pretty big hurdle to comprehension even without compression because we are thinking in human terms. Imagine all of the prerequisite human knowledge you overlook to even approach the concept of an encyclopedic article describing something. Aliens might share knowledge by hitting each other with telepathic darts for all we know, having a completely different understanding and implementation of information, and words might require years of study on their part to comprehend. Even the golden record carries a lot of assumptions. What we know about the universe is not necessarily final, even with rudimentary things like information theory.
In the end it's a bunch of bytes, numbers really, on a disc. What are numbers, even? What if they have a totally different non-numeric system to quantify and explain their existence?
Think about finding an extraterrestrial storage device like this from our perspective. I'd safely predict 20 years before we even extract one byte of data, and a lot of that time would be arguing over it, probably. Although thinking about an alien Nobel ceremony for cracking the "extraterrestrial ceramic Wikipedia" is a pretty amusing thought.
I'm only half being sarcastic, as I've gotten lost in some of those articles trying to figure out who someone is... while I'm not sure of the encyclopedic value of those articles, they definitely have some entertainment value. For that matter, it may be worth clarifying fictional characters from those that are historic, or based on historic events.
One concept that always got me is the premise of an alien culture without sarcasm. They would have a very hard time with human culture/history.
Mexican-American war had twenty thousand words of discussion over what dash to use, and that knowledge isn't transferable even to other dashes used in title on WP.
Here's 15,000 words on dashes. The result? No concensus.
I'm waiting for the meme that conclusively starts a war. The assassination of Archduke Franz Ferdinand in 72 point Impact. That'll be a fun one for future history books to explain.
Its about humanity trying to reverse engineer a message from space that has very few bits. One of the morals is that humans would be able to decode crazy encodings provided enough time. And more data helps a lot. With 20 GB, even compressed, common patterns could quickly be found.
I don't believe for a moment a race advanced enough to recover the disc wouldn't understand it.
Let's suppose the aliens already did this, but instead of a small disc, they wanted to send a message that no intelligent being could miss. Over a short span of 150,000 years, they redirected a bunch meteors into the moon in a pattern that encodes the last few digits of pi in a simplified resonant-fractal numbering system, which proves they know the angular momentum of the universe with fair precision. Clear and convincing evidence that would be visible throughout the solar system.
So yeah, I think no matter what we do to try to communicate with an alien intelligence, they would have to be very much like us (probably our own descendants or - who knows - ancestors) to even recognize the presence of the simplest message, much less decode it.
There is no last digit of pi.
http://rosettaproject.org/disk/concept/
Of course then you need to work out what the language is actually saying, but plain "glyph retrieval" can be done with a desktop microscope and some time. An alien that operates in a roughly human way (has eyes, language, linear writing) would probably understand that it encodes meaning, even if it ends up like Linear A and undecipherable.
Once you introduce a few words, the rest may be decipherable from context, especially with such a large corpus. E.g. certain words will cluster together often, and once you know one, you can guess at the others, which lets you guess at others, and so on.
The linked article makes a big point about it not just being the English wiki, but 300 languages instead.