Paula Cleggett-Haleim
Headquarters, Washington, D.C.                      June 14, 1990
(Phone:  202/453-1547)

Jane Hutchison
Ames Research Center, Moffett Field, Calif.
(Phone:  415/604-4968)


RELEASE:  90-82

MAKING FRESH VEGETABLES ON LONG-DURATION SPACE TRAVEL


     The first working model of a "salad machine" that eventually 
will provide a variety of fresh vegetables for astronauts on long 
voyages is now growing its first crop at NASA's Ames Research 
Center, Moffett Field, Calif.

     Dr. Mark Kliss, project manager and principal investigator, 
said one of the first things astronauts and submariners ask for, 
following days or weeks of eating freeze-dried or preserved 
foods, is fresh produce.  "Our goal is to produce such a variety 
of fresh salad vegetables for consumption by the crews of Space 
Station Freedom and other long-duration missions," Kliss said.

     The presence of plants and the ability to "cultivate" a 
garden also can improve the crew members' morale by providing 
something for them to nurture and by offering a creative outlet 
during their free time, much like tending a garden on Earth, he 
said.

     Garden-variety plants such as leaf lettuce, carrots, 
radishes, onions, sprouts, tomatoes, peppers and cucumbers are 
being considered for inclusion in the salad machine.  Most 
candidate vegetables have very similar temperature, humidity, 
lighting and nutrient requirements, thus simplifying the 
environmental control system.  Because of limited space, some 
plants will be smaller than the varieties commonly found on 
Earth.

     Tomato plants, for example, will be less than 12 inches 
high.  And because there is no gravity, some of the vegetables 
will grow "upside down" or "sideways," although in the 
weightlessness of space there is no true "up" or "down."

     Kliss' goal is for the salad machine to produce three salads 
per person per week for a crew of four.  It also will recycle the 
water transpired by plants back into the nutrient delivery 
system.  Eventually, Kliss hopes the salad machine can use 
recycled water to grow plants and produce potable water for crew 
consumption. 

     It also will furnish oxygen-enriched air to the cabin 
environment after particulates and excess water vapor are 
removed.  Food production, carbon dioxide scrubbing, oxygen 
generation and water purification are key functions of the 
"bioregenerative" life support systems being developed by the 
Advanced Life Support Division at Ames.

     Project engineers also face formidable engineering 
constraints.  The amount of space available is limited to a 
single standard space station rack of 36 inches by 41.5 inches by 
80 inches, or about 28.2 cubic feet of growing volume.  The 
machine must operate on less than a kilowatt of power, produce a 
minimal amount of waste heat and provide light for the plants.

     A nutrient delivery system must be designed which can 
provide water and necessary nutrients to the growing plants, 
while keeping fluids in place in microgravity, or weightlessness 
of space.  Kliss said that proper humidity will be maintained by 
recycling condensed water vapor, which also will decrease the 
amount of resupply water needed.

     The process of growing plants in the salad machine should be 
relatively simple.  Seeds, contained in a cassette for ease of 
handling in microgravity, will be germinated for a few days.  
Once the seeds sprout, they will be placed in the plant growth 
chamber containing the nutrient delivery system.  Kliss expects 
the activity of "planting" seed cassettes and harvesting mature 
plants to require 15-20 minutes of an astronaut's time every few 
days.  By applying commercial hydroponic (soil-less) growing 
techniques, plant growth time from seed to harvest is much 
quicker than for field-grown counterparts.

     Kliss hopes to have the salad machine fully operational by 
Space Station Freedom's scheduled completion later this decade.