"Yes. Drac, try orienting us. I did it ten minutes ago." I shoved him
at my equations, giving the angles with the Sun, Earth and Moon which
we should now have. "There's our flight course as it ought to be.
Measure how we're heading, actual position. If it's what it ought to
be, with the plate-combinations I'm using, then I'm crazy."
"Oh, you're just naturally apprehensive," Grantline said.
But we were not where we should be. The _Cometara_ was off her
predetermined course. And then I realized the factor of error. There
was a gravitational force here for which I was not allowing. The
error was not within the _Cometara_; she was responding perfectly. But
there was a force upon her, and not that of the Sun, Earth, Moon or
the distant starfield. I had calculated all of these. It was something
else. Some gravitational pull, so that we were not upon the course of
flight we should have been on.
"But what could be wrong?" Grantline demanded.