"Launching radioactive material through the Earth's atmosphere brings safety concerns. You have to have a special license to do that, but it is not insurmountable," says Dr Simeon Barber, planetary science specialist at the Open University.
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Author(s): Zhiyuan Huang, Lidong Ma, Jianbao Zhang, Dongpeng Hua, Qing Zhou, Lei Yang, Ji-Jung Kai, Haifeng Wang，详情可参考heLLoword翻译官方下载
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