A NASA-supported scientist is learning how to use carbon dioxide–the main gas in Mars’ atmosphere–to harvest rocket fuel and water from the red planet. When astronauts first go to Mars, it’ll be difficult for them to bring everything they need to survive. Even the first tentative explorations could last as long as two years–but spaceships can only carry a limited amount. “We might have to do what explorers have done for ages: live off the land,” says chemical engineer Ken Debelak of Vanderbilt University.