Trump Pledged to Send Astronauts to Mars. Here’s Why That’s Challenging.

-7 million milesEarthMars The distance between Earth and Mars constantly shifts as they move around the sun, ranging from about 35 million miles to 250 million miles. To conserve fuel, spacecraft don’t launch toward the current position of Mars. Instead, they wait until the planet is properly aligned and then cruise to where Mars will be — seven or more months in the future. EarthMars Launch today Mars in 7 months Arrival in 7 months Mars and Earth come into alignment every 26 months, so time is one obstacle to President Trump’s pledge to launch astronauts to plant a flag on Mars. There are only two launch windows during his presidency, in late 2026 and late 2028. SpaceX’s Starship is the only vehicle that has a chance of being ready for an uncrewed mission to Mars in 2026. Elon Musk is developing the spacecraft with the goal of populating Mars and has suggested that he will launch multiple Starships in 2026 to attempt to land there. If those uncrewed missions were successful, the earliest that astronauts might hypothetically leave for Mars would be in late 2028, shortly before the end of Mr. Trump’s presidency. Starship has successfully reentered the Earth’s atmosphere on test flights, but it has not carried astronauts, landed on another world, lifted off from another world without a launching pad or shown that it could safely return to Earth from Mars. And humanity has never tried sending astronauts to another planet. A report on astronaut health by the National Academy of Medicine noted that humans are “the most complex component in the design of long-duration missions into space.” Sending humans to Mars would require advances in life support, space suits, medical and psychological care, food, nutrition, hygiene and bioethics to keep the astronauts healthy and happy for more than two years in isolation, without real-time communication with Earth.