We're still not sure if we can Mark Watney our way through a Martian mission, because soil on the red planet contains heavy metals toxic to humans, including lead and arsenic. A team of scientists from the Wageningen University in the Netherlands, however, found out that radishes, peas, rye and tomatoes grown in Martian soil are safe to eat after years of research. The scientists have been growing different types of plants in soil that NASA developed to simulate what's found on the red planet since 2013. While they haven't exactly eaten any of them yet -- and team leader Wieger Wamelink admits radishes are still best grown on Earth -- they confirmed that these four can grow on Mars without absorbing dangerous levels of heavy metals.