NASA is not planning to build a new shuttle to replace Columbia, as the current shuttle program is expected to retire after completing the International Space Station (ISS). The focus is shifting towards the Crew Exploration Vehicle (CEV) program, which aims to develop a more advanced spacecraft for lunar missions and potentially Mars. Concerns about the cost-effectiveness and safety of the shuttle program have led to discussions about privatization and collaboration with international partners like Russia. The feasibility of future manned space missions is under scrutiny, with many questioning the necessity of human spaceflight unless targeting significant goals like Mars. Overall, the future of NASA's shuttle program appears limited, with a stronger emphasis on new technologies and partnerships.