Most of the experts came to the conclusion that the work was not being done by native inhabitants of Mercury. Even for the most respected scientists, it was considered unlikely that intelligent life from beyond the solar system was behind the mysterious activity, but to Aki Shiraishi, the conclusion that aliens were involved was the only rational explanation.
Was Mercury a good choice for aliens? It had a wealth of metallic minerals and, naturally, a plethora of solar energy for the harnessing. Because it was also close to the sun’s gravity, Mercury had a high concentration of heavier elements, including an iron core just beneath its crust. With solar radiation on Mercury seven times the level on Earth, there was a more-than-sufficient power source for excavation and building.
With the possibility of an extrasolar life-form only a hundred million kilometers away, humanity’s great institutions had to make a show of doing something proactive. The United Nations created rules for interstellar diplomacy based on the Post-Detection Protocol that had been adopted by the International Academy of Astronautics in 1989. PDP was devised by researchers in the Search for Extraterrestrial Intelligence (SETI) project and gave important instructions about what to do when extraterrestrial contact appeared imminent:
Duly confirm the existence of the extraterrestrial civilization.
Inform the relevant organizations and agencies, starting with the U.N., followed by the mass media.
Share observational results.
Protect the communication frequencies being used to make contact.
Do not respond to any incoming messages without the proper authorization.
Replies were to be sent only after thorough discussion among the U.N. Peaceful Use of Space Committee, national governments, and certain non-governmental organizations. Based on the consensus reached, the U.N. would adopt a resolution finalizing the response to the communication. There was doubt that the PDP could pass a vote because the planet had so many political, religious, and personal differences about how to handle communication with other people on Earth that it seemed unlikely they could agree on how to talk to an alien species.
Finally, the U.N. hammered out an addendum to the PDP that said, simply, “Communication will be restricted until there is confirmation that the other party is an intelligent form of life.” In other words, the sanctioned dialogue with the extrasolars was limited to, “Greetings. We are intelligent beings. Are you?”
Nevertheless, scientists began devising means of communication, since there was no point in deciding what to say otherwise. The first message composed at the SETI Institute at the University of California at Berkeley was a pulse that transmitted a series of prime numbers, followed by symbols indicating that the message was coming from the third planet from the sun. Inspired by the message that was included with the Pioneer plaques, the first human-made objects that ever left the solar system, the communiqué also included a schematic of the spin-flip transition of hydrogen. Prime numbers do not occur randomly in nature. A communication composed of them would be prima facie evidence of intelligence. The transmission used the Arecibo radio-telescope observatory and NASA’s global deep-space network. The transmission points were synchronized with the earth’s rotation. The message was always sent from the side of Earth facing Mercury. To avoid interference, global restrictions were placed on using radio waves and the signal was broadcast on every possible frequency. Given the size of the construction project the extrasolars were conducting on Mercury, it seemed logical that the extrasolars would have at least one communications receiver in place. Still, Mercury remained silent.
MATERIAL CONTINUED TO seep from the planet’s surface. Before long it was visible even with consumer telescopes. Scientists observed particles entering a circular orbit around the sun with a radius of forty million kilometers. The behavior of the mass could not be explained by gravity or orbital dynamics. Scientists speculated that the floating particles were acting as planar mirrors, using light pressure to correct their orbit. That would require the production of eighty thousand tons of miniature space machines per second, a preposterous amount to Aki, but she knew that such a level of production was the only possible answer.
Eighty-eight days of head-scratching passed on Earth—and a year passed on Mercury—before the shape became clear: a ring eighty million kilometers in diameter encircled the sun.
News outlets scrambled to explain:
“This light bulb, with a diameter of 16.5 inches, is the sun,” explained one newscaster, the camera following as he walked. Then, panning out, there was a circle twenty-six feet wide with the light bulb at its center, slightly tilted and not quite parallel to the floor.
“This circle represents the enigmatic Ring that extrasolars on Mercury seem to have built, though perhaps this could still simply be a natural phenomenon never before seen by humanity. Our artists have made it thicker so you can see it, but if it were drawn to scale it would be as thin as a piece of dental floss. Magnified observations show that it’s about three kilometers tall and shaped like a ribbon standing on its side and wrapped around the sun like a wall. There are also reports of some kind of gas cloud, or particulate cloud, surrounding the Ring.”
The anchorman jogged past the ring. A table placed near the edge of the large room had a small blue pellet resting on a white china plate.
“I’m fifteen meters from the light bulb; the relative position of Earth. This little ball is our home planet.”
Over time, the Ring became more and more pronounced until it was visible to the naked eye. When the sun set each evening, people gathered on rooftops, hillsides—any spot with a clear view of the horizon—and stared at the western sky, chanting, weeping, and sometimes just sitting in lawn chairs drinking beer or barbecuing. For an hour after sunset and an hour before sunrise, the Ring could be seen in the dim sky, looming diagonally above the horizon like a glowing silk thread.
At first glance, it looked like the fibrous rings of Saturn or Uranus. Closer observation revealed that it had no orbital movement and was stationary relative to the sun. People wondered what kept it from getting sucked into the sun’s gravity well, and the best theory was that the Ring was composed of solar sails, giving it the power to stay in orbit. The inner side of the Ring was black. By absorbing sunlight across the inner vertical face, one square meter of surface could hold 0.7 grams of material in position. By Aki’s calculation, the Ring was as thin as a sheet of aluminum foil.
Then, a newly discovered fact shook the world. The height of the wall formed by the Ring was growing at the rate of fifty kilometers per day.
There was no visible form of construction observed. At the current rate of expansion, most experts calculated that it would take fifty years for the height of the Ring to cause total solar eclipses twice a year in May and November, when the plane of the earth’s orbit intersected the plane of the Ring. Meteorologists and planetologists predicted a crisis; though the total eclipses would only last a day, the eclipses would be preceded and followed by partial eclipses that would last more than two months, thereby blocking 10 percent of the earth’s annual sunlight.