Taking plants along on a trip isn’t a new idea. Since early explorers wanted familiar foods to ease their transition to foreign lands, they often took seeds and plants with them. Space travelers do much the same thing. In fact, as space trips become longer it will be necessary to grow food in space. A nine-month trip to Mars, each way, would require huge amounts of food and water. The cost of taking anything into space is about $22,000 per kilogram. Because of this, it’s not practical to send everything needed for such a long journey, only to be used once and discarded. Everything used in space must have several uses.