You don't actually need to use lead. The key phrase there is "effective strength" so if you have a massive supply of energy at your fingertips, it may be feasib

You don't actually need to use lead. The key phrase there is "effective strength" so if you have a massive supply of energy at your fingertips, it may be feasible to divert some of it towards the creation of an artificial magnetosphere similar to Earth's own. Of course you could also use water (obviously in much greater volume), which is a good thing to have in large quantities anyway while you're in space, and is evidently not all that uncommon, at least throughout our solar system.