Salad seeds（生菜种子）that went on a round trip to outer space and back grew at a slightly slower rate than the ones on earth, scientists found, thanks to thousands of young people who helped conduct an out-of-this-world experiment.
The project started in 2015, when British astronaut Tim Peake took a million seeds with him on his journey to the International Space Station （ISS）. The seeds spent six months there before they were sent back to Earth in 2016. In a message sent from the ISS, Peake said the purpose of the science experiment was to find out if the conditions in space affected the seeds' ability to grow.
Around 600, 000 pupils at 8, 600 schools in the UK were then asked to grow the rocket seeds that had been to space, along with regular seeds that had never left the planet. Peake described the experiment as "one of the largest and most inspirational experiments of its kind".
The results of the study, which have just been published, found that the space seeds grew more slowly than the ones that had stayed on Earth. Researchers on the experiment said this was due to the stresses of space travel, such as the zero-gravity（零重力）atmosphere and high levels of cosmic rays （宇宙射线）, which slowed the growth of the plants.
Now researchers are hopeful that if the seeds are properly protected, it might be possible to grow plants during future space tasks to other planets. Dr Jake Chandler, from University of London, who led the study, said, "The possibility of eating home-grown salad on Mars may be one small step closer. "
