Mr Lemmens said that future spacecraft "should be designed in such a way that they can take themselves out of orbit safely, preferably by doing controlled re-entries".
This Tweet is currently unavailable. It might be loading or has been removed.
，详情可参考服务器推荐
Thanks for signing up!
A certain type of nerd finds it beautiful and alluring to work on
BBC中文接觸到的居民面對的回覆問卷期限不一。