&gt; Thrusters require energy and reaction mass...<p>Yes, obviously. (Unless that microwave drive from earlier this year turns out to be really for reals).<p>&gt; For every course change of the spinning construct you&#x27;d need to stop the rotation, reel in the drum...<p>I&#x27;m not convinced that this is entirely true. Doing so would simplify the math required to perform the course alteration, but I expect that altering the course of the craft <i>while</i> it is spinning is not impossible.<p>Regardless, as pavel_lishin mentioned in the first comment you replied to in this subthread, you can reel the tether in when making craft course changes.<p>&gt; On top of that you can&#x27;t do work on the outside of the space ship since everything (including the space walker) would fly away.<p>Unless -as you go on to say- you&#x27;re attached to the outside of the craft.<p>&gt; Storing oxygen&#x2F;hydrogen over long periods is an issue in itself.<p>...if you&#x27;re going to take a long journey in space, this is one of the problems you&#x27;re gonna have to have solved, no?<p>So, I&#x27;m a little confused.<p>We go from:<p>&gt; so how do we stop the rotation while reeling in for acceleration? Shortening the tether would accelerate the objects at the end...<p>to:<p>&gt; Thrusters require energy and reaction mass (or chemical propellants). ... It _is_ a low level physics problem, but the practical implications are massive.<p>You&#x27;re moving the goalposts. Your first question asked &quot;How do we maintain the speed (and -thus- the g-forces in the craft) while altering the length of the tether?&quot;. Your follow-on comments to the answer to your question say -in a nutshell- &quot;Gosh, solving that problem would make maneuvering too hard, and is thus kinda impractical.&quot;. :&#x2F;