He immediately went back to work until, at last, she had a shuddering orgasm, too.

"Thank you," she said, smiling at him, as they now lay side by side, each facing the other.

He lightly traced the line of her check with his index finger. "For what?"

"For, um, making sure that I…"

His eyebrows went up. "Of course."

"Not every guy, you know, cares…"

She was totally naked, and the room’s lights were on. He was delighted to see that the freckles were everywhere, and that her pubic hair was the same coppery shade as the hair on her head. She seemed totally at ease with her nudity. Now that they were done, he wanted to scoot under the sheet. But her body was pinning the sheet in such a way that he couldn’t get under without making a big deal out of it. But as her finger played with the hair in the middle of his chest, he was uncomfortably conscious of her scrutiny.

"No scars," she said, absently.

The dermal regeneration had gotten rid of all Don’s old ones. "Just lucky, I guess."

"Well," said Lenore, whapping him playfully on the arm, "you certainly got lucky tonight." And she made a big O with her mouth.

He smiled at her. It had been amazing. Tender yet spirited, gentle and vigorous all at once. It wasn’t quite sleeping with a supermodel — but it would do! Oh, yes, it would do!

His hand found her nipple, and he tweaked it lightly between thumb and forefinger.

"The pallid bust of Pallas," he said softly, smiling at her.

Her eyes went wide. "You’re the first guy I’ve met who knows more of that poem than just the ‘nevermore’ part. You don’t know how sick I got of people intoning ‘nevermore, nevermore’ at me."

He stroked her breast gently, and said:

"Wow," said Lenore, softly. "I’ve never had a guy recite poetry to me."

"I’ve never had a girl challenge me to Scrabble before."

"And I want a rematch!" she said.

He raised his eyebrows. "Now?"

"No, not now, silly." She pulled herself closer to him. "In the morning."

"I— I can’t," he said. He felt her stiffen against him. "I, um, I’ve got a dog."

She relaxed. "Oh. Oh, okay."

"Sorry," he said. He meant "for lying," but let her take it to mean "for not being able to stay." He scanned around the room for a clock, saw one, and his heart jumped.

"Look," he said, "I, um, I really do have to get going."

"Oh, all right," said Lenore, sounding not at all happy about it. "But call me! I’ll give you my number…"

Don fondly remembered the trip he and Sarah had taken to New Zealand in 1992.

But Carl had been conceived on that trip, and his birth had put an end to them doing much traveling together for the next couple of decades; Sarah still went all sorts of places to attend conferences, but Don stayed home. He’d been quite sad to miss out on going to Paris with her in 2003 for a symposium with the nifty name "Encoding Altruism: The Art and Science of Interstellar Message Composition." But he had gotten to go to Puerto Rico with her in 2010 for the transmission of the official reply to Sigma Draconis. His brother Bill looked after Carl and Emily while they were away.

The city of Arecibo is about seventy-five minutes west of San Juan, and the Arecibo Observatory is ten miles south of the city, although it seemed much farther, Don had thought, as they were driven there on the twisting mountain roads. The landscape was all karst, said the driver: limestone that had been eroded to produce fissures, underground streams, caverns, and sinkholes. The Caverns Rio Camuy, one of the most spectacular cave systems in the world, were southwest of the observatory.

And the great radiotelescope dish itself had been built here because nature had kindly provided a thousand-foot-wide sinkhole, perfectly shaped to hold it.

Don had been surprised to see that the dish wasn’t solid. Instead, it was made of perforated aluminum slats with gaps between them, all held in place by steel guys.

And beneath the dish, in the partial shade, was plenty of lush vegetation, including ferns, wild orchids, and begonias. Around the observatory grounds, Don was delighted to see mongooses, lizards, fist-sized toads, giant snails, and dragonflies.

He and Sarah were put up in one of the VSQs — "Visiting Scientist Quarters" — a wooden cabin on a hill, raised up above the uneven ground on ten cement-block pillars. The cabin had a small porch (excellent, they discovered, for watching the afternoon thunderstorms), a tiny kitchen, one little bedroom, a small bathroom, and a rotary phone. A boxy air conditioner was installed just below one of the windows, all of which were covered on the outside by wooden shutters.

Besides being technically a good choice for sending the message, Arecibo was also good symbolically. Seventy-nine-year-old Frank Drake was on hand in the control room overlooking the great dish when Sarah used a USB cable to connect her Dell notebook computer, containing the master version of the response, to the transmitter. Drake’s message to M13 — until this moment, the most famous SETI broadcast — had been sent from here thirty-six years previously.

As planned, the response contained a thousand completed surveys, chosen at random from the 1,206,343 sets of responses that had been uploaded to the website Sarah had helped create. Well, actually, truth be told, 999 of the sets were randomly chosen; the one thousandth was Sarah’s own set, shuffled into the middle. Not that she’d snuck it in. Rather, after Don and Carl had put the notion in her head, she’d broached the topic of including her own answers at a meeting, and the PR officer for the SETI Institute had loved the idea. It made for a great human-interest angle, he said.

At the transmission ceremony, commemorative CD-ROMs containing archival copies of the message were distributed to key researchers, but the actual responses people had given weren’t being made public. As per the Dracons’ request, the answers were still being kept secret, so that the participants wouldn’t be influenced by each others’ responses when dealing with follow-up questions that might come at some point.

The control room had large floor tiles set on the diagonal, alternating in a checkerboard of beige and brown; it made Don more dizzy to look at them than it did to look out the angled window at the gigantic dish, and the 600-ton triangular instrumentation platform mounted above it.

Scientists, press, and a few other spouses were jammed into the control room.

Electric fans were sitting on pieces of equipment or clamped to them, but, even though it was still early in the morning, the heat was oppressive. Don looked on as Sarah sat down at the central L-shaped desk and brought up the response on her notebook. He’d suggested she come up with a memorable phrase — her own "one small step" speech — but she’d declined; the important message was what was going to be transmitted, not anything she said. And so, with nothing more than an "All right, here we go!" Sarah clicked the on-screen button, and the word "Transmitting" appeared on the notebook’s display.

Shouts went up and champagne appeared. Don stood at the periphery, enjoying seeing Sarah so happy. After a bit, the beefy, silver-haired representative of the International Astronomical Union started tapping on the side of his champagne glass with a Mont Blanc pen until he had everyone’s attention.