The Eternal Recurrence

Now a large number of environmental protection declarations can be seen everywhere, but saving the planet is still a very difficult problem. What about space? Exploring outer space has been an important task for mankind over the years. After the exploring how many waste are left in the universe? The wreckage of the aircraft, dust, engines, etc. have been left in space forever. No one knows how the environment of the universe will change in the future. We should seriously consider this issue and take corresponding measures before the situation gets worse. According to Hawking's time-space view, the future can decide the past, and if it can, what can we do for the universe?