<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>I dont get it, they worked on the ISS for years, and they will still be working on the ISS for another 2 years, adding components and other cool things. Everything is very expensive, very much the latest of the latest technology and at the same time work done there is unique in every aspect. Then, BOOM! They dont expect this to last past 2020!!! What the heck? Who spends 100 billion dollars and then all the sudden does not consider keeping it alive for at least 20 years or more? Why not replace the oldest module with an updated version? A more durable version, or maintain the thing somehow? <br />Posted by MarcoSpace</DIV></p><p>Twenty years is a long time for a human spacecraft that can't land and be overhauled between missions. No previous station will have lasted this long. Even on Earth, not many vehicles, ships or aircraft last for this length of time. Spacde is a punishing environment, especially in LEO. Extrme temperature changes many times a day, space debris, atomic oxygen, radiation, aandd general wear and rear by the hundreds of people who will hve lived and work there will take their toll. Plus there wll be general obsolescence. After 20 years much of the technology will be obsolete, the questions it is designed to answer answered. It will be time for a new station, or stations.</p><p>Jon<br /></p> <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em> Arthur Clarke</p> </div>