People often say, "What goes up must come down." But the phrase isn't always true, not in space at least.

人們常說 "上有政策，下有對策"。但這句話並不總是正確的，至少在太空中不是這樣。

There are millions of things that humans have shot up into Earth's orbit, and they are still there.

人類將數以百萬計的東西射入地球軌道，它們現在仍在那裡。

Most of them are tiny, but because there are so many of them, these pieces of space junk add up to a big problem. The biggest pieces of space junk are old satellites that don't work anymore.

它們中的大多數都很小，但由於數量太多，這些太空垃圾加在一起就成了一個大問題。最大的太空垃圾是那些不再工作的舊衛星。

However, those inactive satellites are only some of the 30,000 pieces of junk up there bigger than 10 centimeters across.

然而，這些不活動的衛星只是上面 3 萬個直徑大於 10 釐米的垃圾中的一部分。

There are also smaller pieces that are bits of debris from broken equipment, satellites destroyed by weapons tests, or even chips of paint. In total, there may be more than 100 million pieces of space junk flying around our planet.

還有一些更小的碎片，它們是破碎設備的碎片、被武器試驗摧毀的衛星，甚至是油漆碎片。 總之，可能有超過 1 億塊太空垃圾在我們的星球上飛來飛去。

If the junk's orbit is high enough, it stays in space.

如果垃圾的軌道足夠高，它就會停留在太空中。

Because it's still traveling as fast as a rocket, a collision between space junk and a satellite, spacecraft, or space station could be disastrous.

由於太空垃圾的飛行速度仍然不亞於火箭，是以一旦太空垃圾與衛星、航天器或空間站發生碰撞，後果將不堪設想。

The International Space Station (ISS) sometimes has to move itself to avoid hitting pieces of garbage. Some experts fear what's called Kessler syndrome, a situation where a chain of collisions creates so much debris that more collisions are inevitable, making it impossible to put more satellites in orbit around Earth.

國際空間站（ISS）有時不得不移動自己，以避免撞上垃圾碎片。一些專家擔心會出現所謂的 "凱斯勒綜合症"（Kessler syndrome），即一連串的碰撞會產生大量碎片，導致更多碰撞不可避免，從而無法將更多衛星送入環繞地球的軌道。

Cleaning up these pieces of flying junk is a difficult problem.

清理這些飛行垃圾是一個棘手的問題。

People's ideas for doing it range from using lasers to magnets. Space junk hasn't caused a serious disaster yet, but it might in the future.

人們的想法多種多樣，從使用脈衝光到磁鐵，不一而足。太空垃圾還沒有造成嚴重的災難，但將來可能會。

In any case, keeping the space near Earth clean will be important for continuing to make use of space technology.

無論如何，保持地球附近空間的清潔對於繼續利用空間技術非常重要。