Proktols of Neptune

Space-rumor had spun wild tales of horror about Neptune's almost-legendary race of Proktols. But what could rumor know of this hideous reality that faced Space-captain Janus and his captive crew!
Commander Janus stared in bafflement at the power-board of the Patrol ship Wasp . The Deflector needle was still gyrating wildly. That had begun five minutes ago. His lips tightened, and he looked up irritably as the First Mate peered inquisitively over his shoulder.
Better check up on the course again, Devries!
Just did, sir. We're point oh-oh perfect, not the slightest aberrancy.
Janus swore under his breath. I just can't figure it! Must be some object dead ahead to cause this disturbance, but why doesn't our Deflector beam shunt it from us or pivot us around it?
He paced the Control room, stopped and looked over at Ketrik whose eyes were fixed steadily on the visipanel. See anything yet?
Ketrik merely shook his head, not looking up. That panel magnified their course several times, and Ketrik had the sharpest eyes in the Patrol.
Damned if I like it a bit, Janus muttered, staring again at the crazy needle that seemed about to jump its bearings. Devries, tell Blake to cut all jets. We'd better go into a drift until we are a little better able to determine what's wrong.
Devries stepped to the tube and gave the order to Blake in the rocket room. A moment later the Wasp was in the drift. Blake came forward to see what was up. Far behind rolled the hideous green ball that was Neptune, and immeasurably far ahead somewhere was Pluto. Devries stepped again to the chart and saw that the hair-line indicator still had Pluto right on the nose.
I think I've got something, Ketrik spoke from the panel. The men crowded around him, peering into the square of blackness that seemed to swim as Ketrik turned the magnifying dial.
I see it! Blake exclaimed. Something ... a meteor? Looks like it's drifting right at us.
But Ketrik shook his head, and his eyes narrowed. That looks to me like a derelict, and it's my opinion that we're drifting at it.