What do you do if you purchased Lion from the Mac App Store, have no installation disc or USB key, and are suddenly faced with a hard drive catastrophe? In lieu of begging Apple for your very own Lion recovery drive, you can now run Apple's Lion Recovery Disk Assistant. The tool, released Monday, allows users to create a Lion recovery partition on an external drive in the event of a hard drive crash.

Lion—installed from any source—automatically creates its own recovery partition on your drive in the event of a total operating system implosion. When booting from it, it's possible to use Disk Utility, launch Safari, reinstall Lion, or restore from Time Machine. But if the drive itself ends up going bad, users can't access the built-in partition in order to perform those tasks; without physical media, booting from DVD is no longer possible. (As pointed out by Macworld, the new MacBook Air and Mac mini can boot even without the help of an external Lion recovery drive, but older Macs can't.)

Apple's new tool offers a solution to that problem. Users must have an existing recovery partition before creating one on an external drive. They can then run the assistant in order to create a recovery partition on either a hard drive or USB drive, as long as it has 1GB of space. There is a caveat, though: according to an Apple Knowledge Base article, machines that shipped with Lion can only boot from recovery drives created by the same computer, so no creating a recovery drive from your new MacBook Air for your friend with an older MacBook Pro. But if the computer in question was upgraded from Snow Leopard to Lion, it can use recovery drives created by other machines of its ilk.