The Siege of Eternity

Not all of the staff was happy about the new assignments. Gwen Morisaki didn't want to be taken off her Cepheid count, Christo Papathanassiou was, he said, on the very point of a breakthrough in his quanta! approach to cosmology, and he absolutely must have computer time now. Pete Schneyman was worse. He was already glum about Pat coming back-about so many Pats coming back-and reducing him once more to second-in-command (or fifth!), which was probably why he was so irritable when he complained that checking stock images for some serendipitous observation of possible comet-like objects was the kind of thing you turned over to a machine, or, if you didn't want to waste valuable machine time on it, then to some two-for-a-nickel postdoc. The only one who didn't seem to mind was their planetary astronomer, Harry Chesweiler. The solar system was his turf anyway; his only request was that he be allowed to confine his own searching to the plane of the ecliptic, where he might get some useful data for his own studies. Even Janice DuPage, the receptionist, was drawing lines in the sand. She was willing to do what the Pats told her to, especially because it was what the government wanted, but she warned that it better not last longer than a week or so because her vacation was coming up and she wasn't going to miss out on her cruise to the Amazon and Rio de Janeiro . . . not to mention that it didn't make any sense to treat her like some irreplaceable astronomical expert when, geez, Dr. Adcock, she wasn't really any kind of a real scientist anyway, was she?

To all of them the Pats turned a deaf ear. There would be no exceptions. Everybody, and every computer, was to be totally immersed in the hunt for the Scarecrow scout ship. They even impressed into service the Bureau agents, because even an untrained cop could lend a hand now and then.

In principle, the hunt was simple enough. You looked at a recent picture of a section of the sky-recent being defined as anything in the past couple of years, since the Scarecrow scout had dropped its probe off to leech onto Starlab. You compared it with an older frame of the same area, and what you looked for was to see if there was a dot in the new frame that hadn't been there before. There was nothing to it. ...

Notes and Comment

Since the time of the Babylonians at least, probably since the days of the Neanderthals, human beings have scanned the night skies for points of light unaccountably moving among the fixed stars. The first of the wanderers-they were called "planeten," in Greek-were the naked-eye planets, from Mercury to Saturn, as well as the brightest "hairy stars" or comets. With the invention of the telescope the number of wanderers multiplied beyond counting: new planets, from Uranus to Pluto; the myriad smaller rocks of the asteroid belt; comets by the thousand that never reached naked-eye brightness. The tally of bits and pieces of rock and snow that swing though space as part of the Sun's gravitational domain grew so huge that professional astronomers hardly bothered to count them anymore, much less give them names ... until it became a matter of urgency to find the one faint dot among the anonymous millions that was neither asteroid nor comet, but something quite different, and far more worrying.

-The New Yorker

Except that there were some tens of millions of images that needed to be pulled up out of the world's astronomical archives and examined. Except that there were thousands and thousands of those little dots to be considered, since the space around Earth's Sun was crawling with comets and asteroids and bits of cosmic debris of every sort that were not the Scarecrow scout ship. Except that most of the plates had no precise equivalent and one had to be reconstructed.

The computers did the bulk of the work. They were quite good at taking one image of a quarter-degree square section of, say, the constellation Virgo and manipulating it to an exact match with another plate that included most, but not all, of the same stars. The computers were also quite able to identify a point of light in one that didn't exist in the other. The computers were even then able to sort through the infrared and radio images of the same area, if any existed, to see if there were spectrograms or other data that could identify its composition well enough to reject it as normal or flag it for further investigation.

But then it took a human being to decide about that identification, or to order new observations by some available telescope to clarify the point, and to try to figure out an orbit.

All this effort was bearing fruit-of a sort. Previously unidentified comets were being discovered every few minutes. So were new asteroids, if you could call some of those pebbly car-sized things real asteroids . . . but the Scarecrow scout ship remained elusive.

rat Adcock did her best to wake early in