A million-year-old library for aliens

On April 11, 2019, the ship Beresheet crashed on the Mare Serenitatis plain. It was a vehicle built by private initiative. If successful, Israel would have been the fourth country to achieve a landing on the moon, after Russia, the United States and China. But no luck. The failure of a gyroscope triggered a chain of incidents in the ship's software that turned off the engine 10 kilometers above the ground and, although it was able to turn on again later, the vehicle impacted the terrain at about 700 kilometers per hour.

Being essentially an engineering test, the scientific load was limited, just a couple of instruments. Next to them was a ceremonial package consisting of a DVD-like disc on which a series of documents had been recorded, from the Torah to the history of Israel, and its declaration of independence, and a copy of the English version of Wikipedia.

The making of the disk was an initiative of the Arch Mission Foundation, an organization dedicated to preserving the long-term memory of human culture. For millions of years, without going any further. Their policy consists of scattering samples of civilization throughout the cosmos in the hope that, when we or our planet disappear, at least there will be evidence of our existence that future civilizations can collect. More or less, like the plate of the Pioneer or the disks that travel in the Voyagerboth Carl Sagan's idea but on a much more ambitious scale.

The experiment of Beresheet It was not the first initiative of that foundation. He had previously digitized Isaac Asimov's Foundation trilogy and convinced Space X to include it in the payload of its first Falcon Heavy rocket. In a thoughtful publicity coup, this burden was precisely Elon Musk's own red convertible Tesla. His browser screen showed only the phrase Dont't panicanother nod to The Hitchhiker's Guide to the Galaxy, the cult work of Douglas Adams. Asimov's disk was in the glove compartment.

Another initiative placed a copy of Wikipedia on a nanosatellite in Earth orbit. It was in October 2018, aboard a Chinese rocket.

A new miniturization technology

The disk sent to the Moon aboard the Israeli vehicle known as the Lunar Library It was just part of a larger project that aims to seed the Solar System with similar copies. It is – they say – the only way to guarantee their subsistence over millions or billions of years.

Being an object that was supposed to go to the Moon, it faced serious size and weight restrictions. They opted for the familiar appearance of a DVD disc, constructed not of plastic, but of 25 layers of pure nickel, each just 40 microns thick. They form a compact package, but if necessary they can be separated. In total, the disk weighs about one hundred grams on which 30 million pages of text and photos are accumulated, as well as audio, video and binary data files.

Of course, the real problem was not guaranteeing its permanence, but how to store that information so that it is readable in the future by recipients we will never know. Digitizing it is not the answer, as those of us who still have a 5 (or, worse, 8) inch floppy disk know very well. Or old cassette tapes. Simply put, there is hardly any hardware that can read them. And much less, the necessary software.

Analog vs. Digital

The Arch Foundation decided to use analog techniques. That is, images. Any future reader with a sense of sight similar to ours should be able to read and interpret them, as long as their technological level was similar or higher. The communities that had not yet reached that stage were not the target audience for the Lunar Library, nor were they supposed extraterrestrials who communicated through other senses.

The album cover and its next three layers carry photographic reproductions of 60,000 pages. They can be read using a simple 100x microscope, a technology that is supposed to be within the reach of any moderately advanced civilization (on Earth we have had it available for more than four centuries).

The content of these four layers is a series of detailed instructions on how to access the rest of the information, which is digitized in the format of a DVD. A total of 100 compressed gigabytes corresponding to about thirty million pages of text, audio, video and binary data files. The content is very eclectic: from universal literary works to the explanation of David Copperfield's tricks or ancient Vedic texts.

The disc was protected by a rigid envelope, located, in turn, inside the body of the vehicle. That would keep him reasonably safe from the ravages of time, even if the landing was a little rougher than anticipated.

Almost all civilizations have left messages for posterity, some more successfully than others. The Egyptian reliefs can be read after five thousand years; the Roman inscriptions on their monuments, too. Medieval manuscripts have endured a thousand years; the more delicate paper only remains for a few centuries.

Very long-term conservation problems

A large part of the enormous amount of digital information that we have produced in recent times is even more fragile, since it is stored in plastic media, whose life is measured, in the best of cases, in decades. Do you remember that computer mouse that from one day to the next has become clingy touch? Probably the plastic of its casing has begun to depolymerize.

More serious is the fact that, to recover this information, special equipment is needed. A tablet with cuneiform characters, a medieval palimpsest, a Baroque painting are immediately accessible simply by looking at them (and knowing the language, of course); a PDF document, no.

A fairly common medium for long-term storage is microfiche. They use photographic technology and allow a relatively low information density of the order of one page per square centimeter. Their theoretical duration is estimated at several centuries, as long as they are conserved under controlled environmental conditions. In practice it is difficult to guarantee them beyond 50 to 100 years.

The techniques used in the manufacture of the lunar disk offer immensely greater storage capacity and durability. Since nickel is stable, resistant to oxidation and does not undergo radioactive degradation, this material should remain unchanged for millions of years. The disk contains a considerable portion of our knowledge as a legacy to future generations who may or may not be our descendants. Or arrive from other planets.

Now, once all this corpus has been compiled, the problem remains of where to store it to protect it but make it accessible one day. The possibility of burying copies in abandoned mines, under the sea or even in deep strata is being studied, trusting that the future evolution of geology will bring them to the surface. The ocean ridges do not seem like a good place if we want to prevent the library from ending up engulfed in the Earth's mantle. Although perhaps the simplest option is space, perhaps anchored in one of the Lagrange points or on the Moon, like the monolith in the movie 2001. In fact, the operation with Beresheet was a first attempt in that sense.

Another thing is whether its future recipients
will know how to discover it, identify it and take advantage of its contents. The contents of the disk include a type of Rosette stone, with a visual dictionary of seven thousand languages, with multiple alphabets and rules to help interpret the texts. But that does not mean that teaching English to a being from the future is an easy task. Maybe it's not even feasible.

It is possible that a pre-technological society that finds the Library could inadvertently destroy it. Although very resistant to the passage of time, nickel discs are easily scratched and are not immune to a good stone. The promoters of the project allege that perhaps their mere appearance – metallic, iridescent circles, full of symbols unintelligible to the naked eye – turns them into an object of worship that for that very reason protects itself against accidental or deliberate vandalism.

Perhaps – they say – the best defense is to disseminate the product. Leave many copies in many places. Some, obvious and easy to find; others, hidden and inaccessible. And even then, there are no guarantees that anyone will ever find a copy, nor that it will be human or post-human. The worst possibility, they joke, would be that it was found by a telepathic cephalopod alien that feeds on nickel and considers the disk a good dessert.

The controversial biological burden

All these plans were blown up – literally – when the probe Beresheet It crashed on the Moon at more than 700 kilometers per hour. Someone calculated that the energy developed was equivalent to almost thirty kilos of TNT. Whether the Library survived in one piece or in a thousand pieces is something that no one can say for sure, although the promoters of the project point out that, in the worst case, the analog pages would still be readable in each of the fragments, so they consider that Israel has managed to place the first universal library or the first archaeological ruin on the Moon.

Another more controversial issue concerns a last-minute inclusion: a sample of human tissues and a small colony of tardigrades embedded in a layer of resin. These tiny bugs (they don't reach half a millimeter) are famous for their exceptional resistance to the most extreme conditions. They can enter a state of hibernation that allows them to survive at the temperature of liquid nitrogen, in boiling water, in the vacuum of space or in desiccated environments.

The idea was to keep these specimens inside the probe, next to the disk, but the catastrophic end of the mission means that perhaps they were ejected and are now resting on the ground of Serenitatis, waiting for the weather to improve to regain their activity. Specialists say that it is very doubtful that they will survive the cosmic rays and the continuous shower of ultraviolet radiation from the Sun. But, even so, doubts persist. Who knows if the objective of the experiment is met and in millions of years some extraterrestrial archaeologist recovers them and classifies them as valid representatives of the now extinct humanity.

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