As you rightly state, Bahá'u'll'áh affirms that every fixed
star has its planets, and every planet its own creatures. The House of Justice
states however, that it has not discovered anything in the Bahá'í Writings
which would indicate the degree of progress such creatures may have attained.
Obviously, as creatures of earth have managed to construct space probes and
send them into outer space, it can be believed that creatures on other planets
may have succeeded in doing likewise.
- The Universal House of Justice (From a letter dated 11 January 1982
written on behalf of the Universal House of Justice to an individual believer;
included in a Memorandum from the Research Department of the Universal House of
Justice dated 6 August 1996)