><i>Do you think the ISS will ever earn its cost?</i><p>The two problems with answering that question are that that the answer to that question depends on who you are asking, and how exactly do you put a value on the output of a pure research facility?<p>For example, has the Hubble Space Telescope earned it's value? Well that depends on who you ask - if you were to ask a marine biologist (let's assume that scientists have no interests outside their field of study) he would say that it has been nothing but a waste of money that could have been spent on a dozen deep sea submersibles. An astrophysicist, on the other hand, would say that it has repaid its cost a dozen times over. When it comes to assigning an objective value to HST's science results the question is: how do we do it? Number of papers/theses based on HST data? That could work, but suppose the data could have been obtained by other methods if HST wasn't there. Public perception? HST would win hands down there, but what about other telescopes that just don't have the name-recognition of HST: Compton GRO, Chandra, Spitzer, SOHO - aren't they producing useful results? The number of inventions/patents? Could work, but sometimes it can be years before a piece of pure research turns into a patent.<p>That's the problem when you try to objectively measure the value of science - it ain't that easy. Now, subjectively, do <i>I</i> think ISS will earn its keep - I'd have to cautiously say yes. If it is finished, I find it hard to believe that with so much research capability on orbit there won't be some groundbreaking discoveries made, I'd also like to think that ISS engineers were conservative with their calculations much like the Mir designers before them, and that the Station will exceed its design life by two or three times. 3 labs by 30 years is a lot of research time.</p></p></p>