42 Developing, design and research of energy, propulsion systems, satellites, spacecraft and related material, not to include the development, design or research of computer software; Custom design and engineering of energy systems for satellites and spacecraft, not to include the custom design and engineering of computer software; Custom design and engineering of satellites and spacecraft, not to include the custom design and engineering of computer software; Custom design and engineering of propulsion systems for satellites and spacecraft, not to include the custom design and engineering of computer software