Maybe an orbiter/lander combination like Viking. The moon is pretty close to Earth, so I would thing that checking atmospheric pressure should be easy.
Maybe I missed something, but where does it say that the DIRECT launcher would be able to carry payloads like that to the ISS? The MPLM and CAM were specigically designed to be launched and attached to the ISS by a Space Shuttle. Re-designing them to be launched by DIRECT would probably be way...