Krylov turned and pulled open a drawer. Out of the drawer he drew a chart and handed it to Diavilev.
"Do you recognize that?"
Diavilev stared.
"That is the plotted orbit," Krylov said carefully, "of a moon. It is not of course the moon with which you are familiar. But it is a moon circling the Earth, a second moon.
"It is a moon of which no one knows, excepting ourselves and the Kremlin. We discovered it shortly after we arrived, when it passed quite near the station. It is small and dark, too small and non-reflecting to be seen from Earth. It is approximately five miles wide.
"Do you understand?"
Diavilev who had had to digest a great many things in a very short while, was able to nod. Because this was, after all, Diavilev's field.
A second moon, he told Krylov, speaking with some excitement, had long been predicted by astrophysicists everywhere. Since the Earth had been attracting meteors for something like two billion years, it was inevitable that some at least should be captured as moons.
Krylov broke in, nodding with impatience.
"Exactly. And now as to your work. You will see this moon shortly, when it crosses our path again. At that time you will correct the orbit we have plotted. You will also give us the exact mass and speed of that moon. The instruments you will need are already here. Let me emphasize this: You will be accurate. Is that clear?"