space

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Across
  1. 2. chemical element with the symbol He
  2. 5. manned spacecraft
  3. 7. star visible to the naked eye
  4. 8. chemical element with the symbol H
Down
  1. 1. an optical instrument
  2. 3. The US agency responsible for the civilian space program
  3. 4. science that studies celestial objects
  4. 6. one of the two constituent parts of an atomic nucleus