Astronomy vocabulary: select the best noun phrase describing the goal of finding life beyond Earth Context: Hubble Space Telescope tasks include searching for planets and studying interstellar matter. Complete the sentence: "The Hubble Space Telescope will search for planets around the stars, a key to the ______ extraterrestrial life, and examine interstellar dust and gases out of which stars are born." Choose the correct option.

Given data

• Phrase pattern: "a key to the ______ extraterrestrial life".
• Intended meaning: whether life exists beyond Earth.

Concept/Approach
The idiomatic and logical collocation is "a key to the existence of extraterrestrial life" — i.e., understanding whether such life exists.

Option analysis
existence of — correct grammar and meaning. ✅detection for — wrong preposition; natural phrase is "detection of".evidence at — wrong preposition and sense.discovery from — incorrect preposition; "discovery of" would still be less precise than "existence of" here.

Common pitfalls

• Mixing prepositions after abstract nouns (of/for/at).

Final Answer
existence of