 Which effect of Russell's decision to kill Dunbar was likely most surprising to Russell?
Russell didn't think they could remain sane in all this blackness much longer. Four men, thought Russell, held together by an invisible string of gravity, plunging through a lost pocket of hell's dark where there had never been any sound or life, with old Dunbar the first in line, taking the lead because he was older and knew where he was and where he was going. Russell had no idea now how long the four of them had been plunging toward the red-rimmed sun that never seemed to get any nearer. When the four of them had escaped from that prison colony on a sizzling hot asteroid rock in the Ronlwhyn system, that wasn't enough for Dunbar.
 He sabotaged himself by ensuring his loneliness
 The fact that nobody agreed on which sun was the correct one  The decrease in chatter in the communication system  The way the Dunbar died without much drama  He sabotaged himself by ensuring his loneliness