Why does ETS (Exploration Transportation System) make sense as the next step after the Space Shuttle?
The Space Shuttle is a magnificent vehicle that does numerous tasks. Unfortunately, vehicles that are required to do numerous tasks are inherently complex in design. The Space Shuttle is required to transport both astronauts and cargo to/from LEO (Low Earth Orbit) in a largely reusable system. As a result, it is not optimized for either the crew transport mission (top priority: crew safety) or the cargo transport mission (top priorities: dollars per pound to LEO and reliability). This is recognized in the nation’s Vision for U.S. Space Exploration with the direction to “separate to the maximum practical extent crew from cargo transportation to the International Space Station and for launching exploration missions beyond low-Earth orbit.” Lessons from the Challenger and Columbia accidents have shown that safer designs for transporting crews to/from LEO are achievable. In a recent memo, the Astronaut Office stated: “Although flying in space will always involve some measure of risk, it is
