SPACE CENTER, Houston (AP) -- A few decades from now, space travelers living on Mars may think the Pilgrims had it easy.The pioneers who make the 80-million-mile, three-year journey to Mars and back will probably not have the just-add-water-and-heat packaged foods that are aboard the international space station, where the crew orbiting Earth will prepare a Thanksgiving dinner Thursday of turkey, mashed potatoes, corn, green beans and cherry-blueberry cobbler.During the six- to eight-month trip to Mars, space travelers will grow lettuce, spinach, carrots, tomatoes, green onions, radishes, bell peppers, strawberries, herbs and cabbage aboard their spacecraft.And when they arrive at the Red Planet for a stay of about a year and a half, they will cultivate potatoes, soybeans, wheat, rice, peanuts and beans in soil-less hydroponic chambers, according to NASA's food scientists."We will have to grow the vegetables up there because there is no way you can bring fresh, aroma-filled, crunchy vegetables and have it last," said Michele Perchonok, a food technologist at NASA's Johnson Space Center, which is working on a project to send humans back to the moon, and from there to Mars.The wheat will most likely be processed and made into bread or pasta. Syrup could be extracted from sweet potatoes and used to sweeten cookies. And the rice could be cooked or used in drinks."I sort of explain it as an 1800s kitchen with some automation," Perchonok said. "You are going to have to make your peanut butter. If you want a salad dressing, you are going to have to make your salad dressing."The packaged meals astronauts eat in space now do not have a long enough shelf life to be safe for consumption during the entire length of a Mars mission. They also add weight and create waste -- something NASA is going to great lengths to prevent.In fact, NASA wants to recycle just about everything -- even turning the astronauts' sweat and urine back into drinking water.Some studies are looking into the use of fish -- specifically tilapia -- as a way to recycle shower water, toilet waste and the water clothes are washed in. Tilapia eat human waste and are safe for human consumption afterward, said Vickie Kloeris, who manages the Space Food Systems Laboratory at Johnson Space Center.Some crew members are leery of turning urine into drinking water. But Kloeris noted that water-treatment systems on Earth do that already."So in real life you are drinking somebody else's urine instead of your own," she said. "So I'm not sure psychologically which is worse. I think I'd rather drink my own."Copyright 2005 The Associated Press. All rights reserved.This material may not be published, broadcast, rewritten, or redistributed.