The challenges facing Elon Musk and NASA in sending humans to Mars
1. Musk aims to land humans on Mars by 2029. 2. NASA sees 2040 as an audacious goal for Mars colonization. 3. Musk emphasizes Mars colonization as crucial for humanity's future. 4. Technical challenges for Mars settlement include severe radiation and life support. 5. SpaceX's Starship is central to achieving Mars travel ambitions.