Contact - Carl Sagan [45]
Der Heer continued. "Tell me if I have this right, Dr. Arroway. Every day the star Vega rises over the New Mexico desert, and then you get whatever page of this complex transmission-whatever it is-they happen to be sending to the Earth at the moment. Then, eight hours later or something, the star sets. Right so far? Okay. Then the next day the star rises again in the east, but you've lost some pages during the time you weren't able to look at it, after it had set the previous night. Right? So it's as if you were getting pages thirty through fifty and then pages eighty through a hundred, and so on. No matter how patiently we observe, we're going to have enormous amounts of information missing. Gaps. Even if the message eventually repeats itself, we're going to have gaps."
"That's entirely right." Ellie rose and approached an enormous globe of the world. Evidently the White House was opposed to the obliquity of the Earth; the axis of this globe was defiantly vertical. Tentatively, she gave it a spin. "The Earth turns. You need radio telescopes distributed evenly over many longitudes if you don't want gaps. Any one nation observing only from its own territory is going to dip into the message and dip out-maybe even at the most interesting parts. Now this is the same kind of problem that an American interplanetary spacecraft faces. It broadcasts its findings back to Earth when it passes by some planet, but the United States might be facing the other way at the time. So NASA has arranged for three radio tracking stations to be distributed evenly in longitude around the Earth. Over the decades they've performed superbly. But…" Her voice trailed off diffidently, and she looked directly at P.L. Garrison, the NASA Administrator. A thin, sallow, friendly man, he blinked.
"Uh, thank you. Yes. It's called the Deep Space Network, and we're very proud of it. We have stations in the Mojave Desert, in Spain, and in Australia. Of course, we're underfunded, but with a little help, I'm sure we could get up to speed."
"Spain and Australia?" the President asked.
"For purely scientific work," the Secretary of State was saying, "I'm sure there's no problem. However, if this research program had political overtones, it might be a little tricky."
American relations with both countries had become cool of late.
"There's no question this has political overtones," the President replied a little testily.
"But we don't have to be tied to the surface of the earth," interjected an Air Force general. "We can beat the rotation period. All we need is a large radio telescope in Earth orbit."
"All right." The President again glanced around the table. "Do we have a space radio telescope? How long would it take to get one up? Who knows about this? Dr. Garrison?"
"Uh, no, Ms. President. We at NASA have submitted a proposal for the Maxwell Observatory in each of the last three fiscal years, but OMB has removed it from the budget each time. We have a detailed design study, of course, but it would take years-well, three years anyway-before we could get it up. And I feel I should remind everybody that until last fall the Russians had a working millimeter and submillimeter wave telescope in Earth orbit. We don't know why it failed, but they'd be in a better position to send some cosmonauts up to fix it than we'd be to build and launch one from scratch."
"That's it?" the President asked. "NASA has an ordinary telescope in space but no big radio telescope. Isn't there anything suitable up there already? What about the intelligence community? National Security Agency? Nobody?"
"So, just to follow this line of reasoning," der Heer said, "it's a strong signal and it's on lots of frequencies. After Vega sets over the United States, there are radio telescopes in half a dozen countries that are detecting and recording the signal. They're not as sophisticated as Project Argus, and they probably haven't figured out the polarization modulation yet. If we wait to prepare a space radio telescope and launch it, the message might be finished by then,