I am writing a science fiction novel featuring a manned exploration into the Oort Cloud. So to keep things simple as possible, my question is this: is it reasonable to suppose an antimatter-powered spacecraft could travel from Earth space out to a distance of (say) 2,000 AU* within a time-period of around ten months? This would be under a continuous thrust (including deceleration) of 1.6 m/s2 - about the same as our Moon's surface gravity. The one bedevilling problem in all this has been my long-running inability to crack the Tsiolkovsky rocket equation, and do so in ways that would resolve the above issue. And why is this important? To satisfy the demands of the plot, I need to have a clear idea what the ship's mass ratio would be for such a sub-interstellar mission, plus some understanding about the efficiency of an antimatter reactor (beam-core or an antihydrogen-catalysed fusion drive?) Also, there's the question about the quantity of fuel needed for the return trip back to Earth. The plot has its eye on that fuel, which is another way of saying that a large question mark hangs over the quantity issue. The spacecraft, by the way - despite comprising for the most part of supremely lightweight materials - still masses at some 5,000 tonnes, and includes its own 'foldable' revolving space station: the crew are in the Oort Cloud for the long haul. Thanks in advance. *This is somewhat short of the Oort Cloud's inner margins, I agree, but, well. . . stuff happens en route.