If anyone can offer advice to the four NASA astronauts slated to launch Wednesday on a trip around the moon, it’s Harrison Schmitt. Schmitt, 90, left his bootprints on the lunar surface in 1972, as part of Apollo 17 — the final mission in the program, which was the last time humans traveled to the moon. NASA’s Artemis II mission, which is scheduled to lift off as early as 6:24 p.m. Wednesday, aims to kick-start a new era of lunar exploration. The crew plans to circle the moon as a step toward a