I'm surprise no-one mentioned ALICE - aluminium + ice (water). A paste-like substance that's quite a powerful rocket propellant. http://news.discovery.com/tech

I'm surprise no-one mentioned ALICE - aluminium + ice (water). A paste-like substance that's quite a powerful rocket propellant. http://news.discovery.com/tech/nanoaluminum-rocket-fuel.html http://news.discovery.com/tech/nanoaluminum-rocket-fuel.html