[ti:NASA to Launch Two More Helicopters to Mars]
[by:www.21voa.com]
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[00:00.04]NASA is launching two more small helicopters to Mars
[00:05.37]as part of its effort to return Martian rocks and soil samples to Earth.
[00:12.32]Under the plan announced in late July,
[00:15.49]NASA's Perseverance rover will transport soil samples to a rocket.
[00:21.60]The rocket will then launch the collected material off the red planet in about 10 years.
[00:28.86]The two helicopters being built will help NASA's Perseverance rover,
[00:34.19]which is already on Mars.
[00:36.59]The helicopters will load samples onto the return rocket
[00:41.38]if NASA's Perseverance rover breaks down.
[00:45.17]Perseverance already has gathered 11 samples with more rock drilling planned.
[00:52.52]The most recent sample, a sedimentary rock,
[00:55.96]holds the greatest chance of containing possible evidence of ancient Martian life,
[01:02.09]said Arizona State University's Meenakshi Wadhwa.
[01:06.61]Wadhwa is chief scientist for the retrieval effort.
[01:11.08]There's "a diversity of materials already in the bag, so to speak," she said,
[01:17.78]adding that researchers are very excited about bringing the materials back to Earth.
[01:24.52]The helicopters will be modeled after NASA's successful Ingenuity.
[01:30.88]It has made 29 flights since arriving with Perseverance on Mars early last year.
[01:38.12]The helicopter weighs just 1.8 kilograms.
[01:41.93]The new versions will have wheels and arms.
[01:45.56]NASA officials said Perseverance's strong performance on Mars
[01:51.24]has led them to change their plan to launch a separate vehicle.
[01:56.09]Jeff Gramling, director of NASA's Mars sample return program,
[02:02.05]said the new path forward is simpler.
[02:05.22]Each helicopter will be designed to lift one sample tube at a time,
[02:11.07]making several trips back and forth.
[02:14.11]"We have confidence that we can count on Perseverance to bring the samples back
[02:19.41]and we've added the helicopters as a backup means," Gramling said.
[02:25.68]NASA is working with the European Space Agency on the retrieval mission.
[02:31.07]If all goes as planned, as many as 30 samples would launch from Mars in 2031
[02:38.80]and arrive back at Earth in 2033.
[02:42.33]Scientists will then study the samples in laboratories.
[02:47.32]They will be looking for signs of microbial life
[02:50.64]that may have existed on Mars billions of years ago when water flowed on the planet.
[02:58.04]I'm John Russell. 更多听力请访问21VOA.COM