If Elon Musk sees his dream of sending people to Mars come to fruition, then he can rest easy knowing it will be possible for passengers to eat nutritious salads. A NASA-sponsored study in Frontiers in Plant Science found that lettuce grown on the international space station, in what they call “veggie plant growth chambers,” retained most of its nutritional value, including its antioxidant levels. Also, the lettuce leaves didn’t contain any potentially harmful bacteria. So it might be wise for Mars-bound missions to bring along a green thumb and a case of bottled salad dressing.