In the last days of the year 2000, a meteor (later designated Y2000) passed within 480,000 miles of Earth, and so had a chance of a few parts per million of a direct hit. Daedalus is more interested in an event of 10 August 1972, when a meteor weighing maybe 4,000 tons skimmed through Earth's atmosphere, coming to within 58 kilometres over the United States and Canada. Daedalus reckons that such a close entry into the resistive atmosphere must have slowed the object to less than orbital velocity, so that its subsequent trajectory will have intercepted the Earth, possibly over land, but more likely in the sea. If it had hit the land it would surely have been noticed.

Two-thirds of meteors hit the sea anyway; and indeed sea impacts have been blamed for many important events, such as the extinction of the dinosaurs. Yet no sea impact has ever been observed and its remains studied. The chance should surely be taken. So Daedalus recommends that the trajectory of the 10 August 1972 meteor should be carefully analysed. The results will determine where in the ocean the incomer splashed down — somewhere on the great circle extension of the trajectory seen over North America. The area of greatest probability will be an ellipse, very likely over some area of ocean.

DREADCO oceanographers will then study that area, using submersible craft equipped with very sensitive cameras. Daedalus regrets the use of powerful lights by such craft, as they blind all the poor sea-creatures that have evolved sensitive retinas. The workers could also look for an altered magnetic signature of the ocean floor. Daedalus has no idea what his oceanographers will make of the results. In principle, a large hot object hitting the sea should make a giant boiling splash, killing all sea life within a large radius. The remains should then descend to the seabed, which might be deep ooze or teeming continental shelf. Because the impact was only 29 years ago, the main remnant should still be interpretable, even if it is only a magnetic anomaly.

It is possible, of course, that the bolide exceeded impact velocity even after its encounter with the atmosphere — in which case it may still be in low Earth orbit, waiting for a chance to deliver its deadly warning again. But then Daedalus would expect that Earthly radio detection or radar, which failed so signally to detect the near miss of 2000, would have picked it up by now, and would predict a good impact site.