Complex sentence: John Hoffman is a space scientist who developed instruments for Apollo 15, Apollo 16, Apollo 17, Pioneer Venus project, and Giotto mission; also designed the mass spectrometer for the Phoenix Mars Lander mission in May 2008.
Split into simpler sentences: John Hoffman is a space scientist who developed instruments for Apollo 15, Apollo 16, Apollo 17, the Pioneer Venus project, and Giotto mission. He also designed the mass spectrometer for the Phoenix Mars Lander mission in May 2008.