Fresh salads made with a variety of fruit and vegetables are likely to be top of the menu for future astronauts, says a leading US space scientist.

And fresh meat would probably be rare treat in space-based life support systems, said Raymond Wheeler, a crop researcher with the National Aeronautics and Space Administration (NASA).

Wheeler, head of NASA's advanced life support program, was exhibiting at space science forum in Beijing vegetables grown hydroponically in a biomass production chamber in Kennedy Space Center.

"Tomato, pepper, lettuce, radish and onion -- what we call 'salad crops' -- have all passed tests in different temperatures, light intensities and carbon dioxide concentrations," Wheeler said.

Vegetable salads would be the staple food in space. "Though animal protein is also very important, there is an energy advantage in eating plants directly.

"If we feed plants to animals and then we eat animals, both the two steps involve energy waste," he said.

Cost was always a priority consideration in space technologies and complicated food preparation resulted in more expense.

"So there's a big advantage to consider first plants that require little or no processing, like lettuce, strawberries or tomatoes. You can eat them fresh, just wash and chop them."

Very little plant research had been carried out in space. All the food astronauts currently needed was shipped from the Earth.

It was much cheaper to launch food and oxygen than to build a wasteless biological recycling system in space, except for "perishable" food, Wheeler told the 36th scientific assembly of the Committee on Space Research (COSPAR), which runs from July 17 to 22.

"Vegetables and fruit cannot be stored for very long in space. If we can grow them locally, they can be very good supplement to the diet," he explained.

(Xinhua News Agency July 21, 2006)