But no new spaceships entered the solar neighborhood from the empty reaches of interstellar space. As the years passed the people on Earth confronted more pressing problems. Concern about the Ramans, or whoever it was that had created that drab cylinder fifty kilometers long, abated as the lone alien incursion passed into history. The visit of Rama continued to intrigue many scholars, but most members of the human species were forced to pay attention to other issues. By the early 2140s the world was in the grip of a severe economic crisis. There was no money left to maintain Excalibur. Its few scientific discoveries could not justify the enormous expense of assuring the safety of its operation. The great nuclear pulse generator was abandoned.
Forty-five years later it took thirty-three months to return Excalibur to operational status. The primary justification for the refurbishment of Excalibur was scientific. During the intervening years radar science had flourished and produced new methods of data interpretation that had greatly enhanced the value of the Excalibur observations. As the generator again took images of the distant heavens, almost nobody on Earth was expecting the arrival of another Rama spacecraft.
The operations manager at Excalibur Station did not even inform his supervisor the first time the strange blip appeared on his data processing display. He thought it was an artifact, a bogey created by an anomalous processing algorithm. When the signature repeated several times, however, he paid closer attention. The manager called in the chief Excalibur scientist, who analyzed the data and decided the new object was a long period comet. It was another two months before a graduate student proved that the signature belonged to a smooth body at least forty kilometers in its longest dimension.