Describe various ways in which manned space missions have helped astronomers investigate the universe?

Actually we have gained far more astronomical information from _unmanned_ space missions. About the only useful information we've gained from manned missions is the knowledge of lunar geology and history obtained by Harrison Schmitt on Apollo 17, the only scientist who has ever travelled to the Moon. Schmitt's work has led to the universal acceptance of the "Big Splat" theory of the formation and development of the Moon.