The Medusa Chronicles by Stephen Baxter Page A

close to the Earth. It cuts right across our orbit—well, it would if it was in the same plane.”
    â€œRight. This baby travels around its orbit in a little more than a year, and mostly Earth is nowhere nearby. But every nineteen years it comes close. And the closest approach is always in the month of June, for some reason.”
    â€œNineteen years,” Seth said. “So after 1949 . . . June 1968. That’s the next encounter. Next year.”
    â€œRight,” Sheridan said. “But again, it should come no closer than four million miles.”
    Seth said, “ Should come no closer . . . ?”
    Sheridan nodded. “What I’m about to tell you is classified. Wartime, you know, I worked for RCA, Radio Corporation of America. Honest war work. Stayed with them after the war when they developed what became BMEWS—”
    â€œBallistic Missile Early Warning System.”
    â€œVery powerful radar. NASA has been working with the Air Force on more powerful systems yet. You can see the application for space research. You could track craft in deep space, manned or otherwise—”
    â€œOurs or theirs,” Mo said evenly.
    Sheridan looked at him steadily. “Best not to speculate, airman. Anyhow, a couple of weeks back we decided to try to find Icarus, as a test. It’s a nice big target, we know its path, and although it’s a hell of a long way away just now, we figured we should get an echo back from it.”
    â€œBut you didn’t,” Seth guessed.
    â€œNo, we didn’t. Damn thing took some finding, in fact, and when we did find it and tracked it a little to figure out its new path—”
    Mo asked, “How the hell can an asteroid have changed course?”
    Sheridan shrugged. “Your guess is as good as mine. Maybe Icarus took some kind of hit in the asteroid belt. Like a kiss on a pool table.”
    Seth thought he saw it, in one big flash. “ It’s going to hit , isn’t it?”
    Mo looked shocked. “Shit on a stick, Tonto.”
    â€œ That’s why we’re talking about this. It won’t miss the Earth by four million miles this time. It’s going to hit—my God, in June next year?” That month had a particular significance to him and it took him a moment to place it. It would be when Joseph, his older son, would be finishing his first year at school . . .
    â€œThere’s your sixty weeks,” Mo said grimly.
    â€œYou got it,” Sheridan said.
    â€œAnd if this thing does hit . . .”
    â€œRemember Meteor Crater? Dug out by a rock that was fifty yards across? Icarus is a mile across. Most likely impact point is the mid-Atlantic, east of Bermuda . . .”
    In his briefcase of horrors, Sheridan had some preliminary estimatesof the consequences. Seth was appalled. The rock would unleash twenty, thirty times as much energy as an all-out nuclear war. A crater maybe fifteen miles across would be punched in the sea bed. Ocean waves hundreds of feet tall would scour the Caribbean, Florida, and the Atlantic seaboards of America and Europe alike. And with maybe a hundred million tons of rock vaporised and hurled up into the atmosphere, there would be a sun-screening layer of dust in the air that might persist for years, creating a deadly winter.
    Sheridan was watching them, gauging their reaction. “I have the feeling you guys are getting it a lot faster than I did. Took some persuading for me to accept this wasn’t just some tempest in a teacup.”
    Mo shook his head. “We have to stop this bastard, sir.”
    â€œRight,” Sheridan said. “So tell me how we do that.”
    â€œUs?”
    â€œ You. Let me tell you what happened in the couple of days since we figured this out. We reported up through the NASA hierarchy to the President’s Science Adviser. And he walked in on the President.”
    Mo prompted, “And the