The Sparrow - Mary Doria Russell [34]
Mendes looked up from her notes and impaled him with a stare. Very bright, Emilio had told him. Don’t underestimate her. Jimmy cleared his throat. "So, the idea is to map this region of the sky using both radio and light astronomy in synchronized observations. The astronomer who originates the request gives the observatories at least two or three times when we can do the work. We have to work around the celestial conditions and the weather on Earth."
"Why not use orbiting observatories?"
"Liz doesn’t have enough funding or clout for access. But you can do a lot with land-based data. So. Anyway, you get a consensus on the schedule and then you hope it doesn’t rain or something, because that messes things up. Sometimes if there’s a narrow window, we gut it out and do the work even if conditions are bad. Do you want to know about that now?"
"Later, please. Just an overview for now."
"Sure. Let’s see. Once we decide to go ahead, I have to check the noise floor." She looked up. "That means I see if the target region is emitting a signal strong enough to be detected above the background noise. All electrical equipment generates electrical noise—electrons banging around in the metal of the equipment itself. We chill the receivers down in liquid helium to keep them really cold, because cold slows down the movement of the electrons and that reduces the not—" The stare again. "Right. You know that. Okay. If the target signal is really faint, we go around turning stuff off. Computers we aren’t using for the shoot, lights, air conditioners, whatever. Then I choose a calibration signal—a known radio source. I shoot that to tune the system up."
"How do you choose the calibration target? Briefly, please."
"There’s a huge catalog on-line and we pick one near the target signal. Usually I just look at the signal using a virtual oscilloscope. We know what a signal from a calibration source is supposed to look like."
"And if the signal differs from expected?"
All business, Emilio said. Well, she has to eat ...
"Mr. Quinn. If the signal differs from the expected?" she repeated, dark brows raised, stylus poised.
"That’s where the art comes in. Each one of these dishes is essentially handmade. They all have quirks—cabling problems, grounding problems. The weather affects them, the time of day, the ambient noise. You have to get to know a piece of equipment like this. And then when you’ve eliminated everything, you have to use your intuition about what could be causing distortions or interference or stray signals. One time," he said, warming up again, "we thought we had an ET signal, extraterrestrial. We got it every few months but nobody else could confirm. Turned out it was the ignition of this one old school bus and we heard it every time the kids from that school came up here on a field trip."
The Stare. It already had a capital letter in his mind. "Listen," he said seriously, "I’m not just wasting your time telling funny stories. You have to know about stuff like this or your program is going to claim it’s found intelligent life on Mars. And everyone knows there’s only Australians there, right?"
She smiled, in spite of herself. "Ah," said Jimmy shrewdly. "I see you’ve worked with Australians."
For a moment, she struggled to return to sobriety but finally laughed. "There’s no such thing as beer too warm to drink," she said with a very good Australian accent.