Far Rainbow (Далекая Радуга) could also be translated as Distant Rainbow or Faraway Rainbow, and in my humble opinion the latter two sound a bit better. The short novel (повесть) was first published in 1963; our translation (by Antonina Bouis) dates from 1979.
Unlike Escape Attempt, this novel is explicitly linked with the Noon Universe through the character of Leonid Gorbovsky. The "Nooniverse" dates from the earliest joint work of Arkady and Boris Strugatsky (or ABS, as fans often abbreviate their joint enterprise - distinguishing the authorial pair from ANS and BNS as individuals). The authors commented that they would like to live inthe Noon Universe, which is named for the collection of stories (or loose novel?) Noon. 22nd Century.
As you read, note how much more real this society is than Efremov's utopia - and yet how there are still utopian traits, though they are set off against human weaknesses. (Interesitng linguistic detail: did you know that the word "foible" comes from the French word that's now pronounced "faible"? Its opposite is "forte," pronounced like English "fort" rather than Italian (musical) "forte" even though most people will say "It's not my forté.") Part of the appeal of the Strugatskys is the way they introduce anxious notes into the relatively utopian setting of their universe that one might argue sprang from the optimism of the Thaw period. Far Rainbow very clearly raises the issue of how scientific and technical progress interact with human foibles (from petty theft of electric power to grandiose experimental hubris).
I picked this novel out of all the ones written by ABS because there were enough copies available used on Amazon - but it's also a fun read, plus there's the bonus Second Martian Invasion (translated very well by a different translator). The idea of packing together two short novels is one the Soviet publishers also often used.
Questions for reading: