[ti:Japanese Spacecraft Heads Home] [by:www.ljhzhm.tw] [00:00.00]更多聽力請訪問51VOA.COM [00:00.04]A Japanese spacecraft has left a distant asteroid [00:05.38]and started its return trip to Earth after successfully completing its mission. [00:14.52]The Japan Aerospace Exploration Agency, known as JAXA, [00:20.80]said the Hayabusa2 spacecraft left its orbit around the asteroid Ryugu, Wednesday. [00:31.44]The space rock is currently about 300 million kilometers from Earth. [00:40.80]Hayabusa 2's mission was to gather soil samples and information [00:47.24]that could provide clues to how the solar system formed, the country's space agency said. [00:56.76]The spacecraft is to bring those samples back so scientists can study them in a laboratory. [01:06.84]Workers at the command center stood up and cheered [01:11.59]when JAXA project manager Yuichi Tsuda confirmed the departure. [01:20.32]The spacecraft captured pictures of Ryugu as it began its return trip and sent them back to Earth. [01:31.68]The asteroid Ryugu, or Dragon Palace, [01:36.11]is named after a sea-bottom castle in a traditional Japanese story. [01:44.28]Hayabusa2 will continue its "farewell filming" of the asteroid for a few more days, JAXA said. [01:56.60]As the spacecraft travels away from the asteroid and toward Earth it will adjust its position. [02:06.48]It will retreat about 65 kilometers from the asteroid and out of its the gravitational pull. [02:16.92]After that, the asteroid will be out of sight of the spacecraft. [02:24.24]"It's sad to say goodbye to Ryugu," Tsuda told reporters. [02:30.48]"Literally it has been at the center of our lives over the past one and a half years." [02:39.56]The spacecraft will then start its main thrusters in early December to power it back to Earth. [02:51.00]The return trip will take about one year. [02:56.60]"We expect Hayabusa2 will bring us new scientific insights," Tsuda said. [03:04.69]"Not only the data, but tangible samples will be in our hands." [03:12.72]Hayabusa2 arrived at the 900-meter-long asteroid in June 2018. [03:21.88]The spacecraft touched down on the extremely rocky asteroid [03:27.78]two times and successfully collected information and soil. [03:35.40]The first touchdown took place in February. [03:40.32]Hayabusa2 collected surface dust samples at the time. [03:46.44]In July, it collected samples from beneath the surface of the asteroid [03:52.53]after landing in a shallow hole that it had blasted. [03:58.16]The operation was the first of its kind in the history of space exploration. [04:06.92]Scientists said they detected small amounts of carbon [04:12.28]and organic material in the asteroid soil samples. [04:18.84]"They will allow us to explore how carbon, organic matter and water [04:26.12]are scattered around in the solar system, why they exist on Ryugu, [04:34.56]how they are related to the Earth," Tsuda said. [04:40.32]JAXA scientists believe the sub-surface samples contain valuable data [04:47.74]because they are unaffected by space radiation and other forces. [04:54.96]They believe the samples could tell more about the beginnings of the solar system 4.6 billion years ago. [05:06.92]Hayabusa2 is expected to reach Earth in late 2020 [05:12.34]and drop a container holding the valuable samples in the Australian desert. [05:21.40]Tsuda said landing the container at the targeted spot will require precision controls. [05:31.64]Details are still being negotiated with the Australian government, he said. [05:39.52]After Hayabusa2 drops its container, the spacecraft may be used for another mission. [05:48.92]The spacecraft took more than three years to arrive at the asteroid. [05:55.88]But the trip home is much shorter thanks to the current positions of Ryugu and Earth in their orbits. [06:06.60]Asteroids orbit the sun but are much smaller than planets or moons. [06:13.76]They are believed to be among the oldest objects in the solar system [06:19.65]and may help explain how Earth developed. [06:25.08]They may even provide clues about the appearance of life. [06:33.00]I'm Mario Ritter Jr. 更多聽力請訪問51VOA.COM 2019六合图库