 What is ironic about Russell's decision to kill Dunbar?
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.
 If the four men had followed Dunbar, they all would have survived.
 After killing Dunbar, Russell became just as delusional as Dunbar  If Russell had not killed Dunbar, the three men would have never reached their ultimate paradise  The four men were all going to die anyway, but they could have died together.  If the four men had followed Dunbar, they all would have survived.