Energia (with or without Buran) was a very interesting vehicle, and in its three flights, enjoyed a remarkable degree of success. Russia, lacking large test stands, cannot test all-up configurations of the really big rockets prior to launch, so that puts a heavier burden on the first flight. Nevertheless, Energia flew flawlessly on all three flights. (The Polyus launch did end in failure, but it wasn't Energia's fault. The booster on Polyus, designed to fire after Energia was done, didn't. Polyus is in the Pacific now.)<br /><br />But it did have foam insulation around the core stage. Just like Shuttle, Energia's core was cryogenic, running on LH2 and LOX. I don't know if there's much data available about it, although I'm inclined to doubt it. But I have anecdotally heard that it also experienced foam shedding. This may or may not be a contributor to the large number of tiles that were damaged upon Buran's return. It was able to return safely, but it would've been a maintenance headache had they ever had a chance to fly again.<br /><br />It might be cool to strap a Shuttle Orbiter to an Energia, and I have no doubt Energia could manage to load (unused SSMEs and all). Alas, there are no Energias to try it with. <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em> -- The Tenth Doctor, "Blink"</font></p> </div>