2 Taking plants along on a tip 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 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.