Rollback

Yes, he thought. Yes, I’m still here. And I’ll still be here for years to come, long after Sarah’s gone. "Yes."

"I do understand that you’re upset, and, believe me, my heart goes out to you. I’ll flag this double-red. That’s the best I can do. Hopefully someone will get back to you shortly."

Just as he had all those many years ago, when Sarah had been trying to translate the first Dracon message, Don stopped by from time to time to see how she was faring with decrypting the current one. But instead of working at the university, she was struggling with this one in the study — the upstairs room that had once been Carl’s.

The Dracons’ original message, the one picked up in 2009, had been divided into two parts: a primer, explaining the symbolic language they were using, and the meat of the message — the MOM, as it rapidly came to be known — which used those symbols in baffling ways. But eventually Sarah had figured out the purpose of the MOM, and a reply had been sent.

This second message from the aliens also had two parts. But in this case, the beginning was the explanation of how to decrypt the rest, assuming the right decryption key could be provided, and the rest, well, that was anybody’s guess.

Because it was encrypted, not even a single symbol that had been established in the original message was visible in the second part of this one.

"Maybe the aliens are responding to one of the unofficial responses," Don said, late one evening, leaning against the study’s doorway, hands crossed in front of his chest. "I mean, even before you sent the official reply, didn’t thousands of people send their own unofficial responses to the Dracons?"

Sarah looked ancient, almost ghostly, in the glow from her magphotic monitor, her thin white hair backlit from his perspective. "Yes, they did," she said.

"So maybe the decryption key is something that was in one of those messages," he said. "I mean, I know you worked very hard on it, but maybe the Dracons weren’t interested in the official SETI-team response. Whoever they intended to have read their latest message might already have done so."

Sarah shook her head. "No, no. The current Dracon message is a response to our official reply. I’m sure of it."

"That might just be wishful thinking," he said gently.

"No, it’s not. We put a special header at the top of the official reply — a long numeric string, to identify that message. That’s one of the reasons we didn’t post the entire reply we sent on the web. If we had, everyone would have the header, which would have defeated its purpose. The header was like an official letterhead, uniquely identifying the response we sent on behalf of the whole planet. And this reply to our response references that header."

"You mean it quotes it?" he asked. "But, then, doesn’t everybody have it now? Any Tom, Dick, or Harry could send a new message to the Dracons and have it look official."

Her wrinkled features shifted in the cold glow as she spoke. "No. The Dracons understood that we were trying to provide a way to distinguish official responses from unofficial ones. They obviously grasped that we didn’t want everyone who managed to detect their latest message to know what the header was. So the Dracons quoted every other digit from it, making clear to us that they were responding to the official reply, but without giving away what had distinguished the official reply in the first place."

"Well, there’s your answer," Don said, quite pleased with himself. "The decryption key must be the other digits from the header, the ones the Dracons didn’t echo back."

Sarah smiled. "First thing we tried. It didn’t work."

"Oh," he said. "It was just a thought. Are you coming to bed?"

She looked at the clock. "No, I—" She stopped herself, and Don’s stomach knotted. Perhaps she’d been about to say I don’t have time to waste on sleeping.

"I’m going to struggle with this some more," she finished. "I’ll be along in a bit. You go ahead."

Don called McGavin’s office four more times without any luck, but finally his datacom rang. His ring tone was the five notes from a forgotten film called Close Encounters of the Third Kind, the sort of aliens-come-to-Earth story that seemed quaintly passe now. He looked at the caller ID. It said "McGavin, Cody" — not "McGavin Robotics," but the actual man’s name.

"Hello?" Don said eagerly, as soon as he’d flipped his datacom open.

"Don!" said McGavin. He was somewhere noisy and was shouting. "Sorry to be so long getting back to you."

"That’s all right, Mr. McGavin. I need to talk to you about Sarah."

"Yes," said McGavin, still shouting. "I’m sorry, Don. I’ve been briefed on all this.

It’s just awful. How is Sarah holding up?"

"Physically, she’s okay. But it’s tearing us both apart."

His tone was as gentle as one’s could be when shouting. "I’m sure."