“It’s got plenty of room to miss us in.” Rioz watched it thoughtfully. “Besides, if we can’t even tell for sure that it’s getting bigger, how quickly can it be moving? Relative to us, I mean.”
“It doesn’t have to be moving quickly. Its momentum is as large as ours, so that, however gently it hits, we’ll be nudged completely out of our orbit, maybe in toward Saturn, where we don’t want to go. As a matter of fact, ice has a very low tensile strength, so that both planetoids might break up into gravel.”
Swenson rose to his feet. “Damn it, if I can tell how a shell is moving a thousand miles away, I can tell what a mountain is doing twenty miles away.” He turned toward the ship.
Long didn’t stop him.
Rioz said, “There’s a nervous guy.”
The neighboring planetoid rose to zenith, passed overhead, began sinking. Twenty minutes later, the horizon opposite that portion behind which Saturn had disappeared burst into orange flame as its bulk began lifting again.
Rioz called into his radio, “Hey Dick, are you dead in there?”
“I’m checking,” came the muffled response.
“Is it moving?” asked Long.
“Yes.”