Alexei Leonov, R.I.P.

The title says it all, really. Alexei Leonov, one of the three greatest Russian space explorers, died last week after a long and amazing career.

It's hard to avoid the feeling that we're living in a diminished age. We have great plans, great dreams . . . but too often they seem to stay that way. In an ideal world, Leonov could have at least visited the Moon in the 1990s as an honored guest (or even a founding partner of some business venture). But nobody's been back since 1972. There are people born after the last man left the moon who are grandparents today.

Farewell to another one of the greats.