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.
12. Space farming is important mainly because ________.
A.food brought from Earth goes bad easily during space flights |
B.it will keep astronauts busy when they are on long-term space missions |
C.it could provide fresh food and reduce the need to bring food from Earth |
D.it’s a way for astronauts to learn more about the environment in space |
13. What can we learn from the University of Sydney research?
A.Human urine is harmless to plants. |
B.Human urine provides six necessary nutrients for plants. |
C.Urine fertilizer is safer and more productive than chemical fertilizer. |
D.Urine-fertilized plants only release a small amount of carbon dioxide. |
14. What is the biggest advantage of using human urine for space farming, according to New Scientist?
A.It could pave the way for long-term space flights. |
B.It does little harm to the environment in space. |
C.It will greatly reduce the cost of farming in space. |
D.Urine-fertilized plants are healthier and taste better. |
15. What’s the text mainly about?
A.The significance of space farming. |
B.A possible new way to grow food in space. |
C.How to use human urine to produce food in space. |
D.Problems facing astronauts on long-term space flights. |