As the 40th anniversary of the first moon landing approaches (on July 20), artifacts spanning a range of NASA's manned space exploration program—from Mercury and Gemini to Apollo and beyond—are being made available to the public as expensive keepsakes. On July 16, Bonhams & Butterfields New York will auction off about 400 lots that include astronaut apparel and equipment, components taken from Apollo lunar and command modules, and photos and charts chronicling the space program's early days.

The items are expected to fetch anywhere from a few hundred to hundreds of thousands of dollars, with the higher prices going to equipment that's actually been in space (even as far as the lunar surface). For example, Bonhams anticipates an attitude controller assembly from the Apollo 15 lunar lander Falcon, a joystick of sorts that used by the astronauts to maneuver the craft, could command as much as $300,000. A checklist worn by an Apollo 16 astronaut that was attached to the cuff of his spacesuit to help him remember the variety of assigned tasks while exploring the lunar surface could likewise sell for $300,000.

Many of the items have been autographed by the astronauts themselves and come from their personal collections.

For a sneak peek at what's on the auction block, view our slide show featuring 20 of the coolest items.