As I (and at least one other person) have mentioned at the New Workgroup Request page (
http://en.citizendium.org/wiki/CZ:New_Workgroup_Requests), Citizendium could certainly use a Space Exploration Workgroup. It is clearly a distinct field from astronomy, which attempts to describe the natural objects populating the universe, whereas space exploration documents human efforts to actually visit the cosmos.
For example, a page about the Crab Nebula would fall under the Astronomy Workgroup, a page about the Hubble Space Telescope would belong to both Astronomy and Space Exploration, whereas the International Space Station article would only be in the Space Exploration Workgroup.
Some of the important articles that would be included in a Space Exploration Workgroup are:
Space Agencies- NASA
- Japanese Aerospace Exploration Agency
- European Space Agency
- Canadian Space Agency
- Roskosmos
- Chinese National Space Administration
Manned Spaceflight- Mercury Program
- Project Gemini
- Apollo Program
- Space Transportation System
- Orion Program
- Vostok Program
- Soyuz Program
- Apollo-Soyuz
- Mir
- Skylab
- International Space Station
Unmanned Missions- Sputnik
- Explorer Program
- Pioneer Program
- Mariner Program
- Voyager Program
- Pathfinder
- Mars Exploration Rovers
People- Alan Shepard
- John Glenn
- Neil Armstrong
- Yuri Gagarin
Obviously this list is woefully incomplete, and probably somewhat America-centric, but if we get a real workgroup setup everyone will be able to contribute their own ideas to the list (and hopefully their own articles!).