No matter how exciting space exploration sounds, there's a vital point about it that needs to be considered: food supplies. Right now, astronauts typically rely on dry food in airtight bags and cans, since there are strict weight limits on items taken into space. Foods that we take for granted, such as fresh fruits and vegetables, are out of the question for space explorers.
For those who've attempted to grow food during space missions, they've faced many difficulties, including the absence of gravity, and a lack of soil, air and humidity (湿度). However, as Shane Topham, an engineer with Space Dynamics Laboratory at Utah State University in the US, told NASA, "Growing food to supplement and minimize the food that must be carried to space will be increasingly important on long-duration missions."
Great efforts have been made to explore the concept of space farming. Recently, a team led by Federico Maggi at the University of Sydney in Australia figured out how plants can absorb nutrients from human urine (尿), as reported by New Scientist on March 27.
After over 20 years of experiments, the results suggested that human urine could supply three to four out of the six nutrients that plants need. The researchers also found out that urine-fertilized plants produce no harmful by-products, such as carbon dioxide or ammonia (氨).
According to New Scientist, human urine is 95 percent water, with the other 5 percent composed of nutrients which are harmful to the human body but not to plants. The advantage of this urine-fueled life support system is obvious: By recycling liquid waste and producing food, an efficient cycle will be created.
And most importantly, said New Scientist, the duration of space missions will be greatly extended to "20 years of flight", meaning we may be soon sending astronauts on missions to Mars, or even beyond.
