CEV or constallation Lockheed Martin or Boeing design no matter what you call it under NASA's current mind set still does not meet the safe haven requirement as indicated by Nasa's cancelling of the Hubble Shuttle mission. when looking back in time to the previous programs of space exploration.

It has been so long since the Mercury, Gemini and Apollo were started there has never been any concerns about sending any single ship into Space and this includes the Russian's and now the Chinese with regards to space exploration. This was not even give a thought of even after the Apollo 13 accident which utilized the Lunar Modules resources ensuring a small
ability for safe return.

Only space station had this feature of having safe haven in that with Skylab we had the apollo capsule that the crew came up to the station in, the Russians Mir and now the ISS which now have the Soyuz capsule waiting if one should be needed.

I say unless Nasa Plans on having this feature present for each launch no matter what type of vehicle is used, then maybe we should live with the chance as we always have with regards to having a single ship in orbit but be ever more vigilant with the response to anything from here on what ever may affect safety of the crew.

Options for the current shuttle could be to place a Soyuz capsule or something simular or even the new CEV / Constellation within the cargo bay for when a mission is not to the ISS.

Space is just a new roadway rather than with cars, busses, trucks, tractor trailers ect.., rails for trains or subways, planes and helicopters for the sky. We each require different vehicle styles in order to achieve the goal of transportation, carrying of goods or materials and much, much more.

Whether this new space vehicle be an orbital space plane, capsule or Crew Exploration Vehicle Astronaut transportation to and from space requires many types of crafts.

I think some more thought on the space shuttle is needed in regards to it's task of being a space truck and of it's future alternative usages or new mission in that as it nears or finalizes the Space Station building construction phase. I feel so long as the Station is present very heavy or uniquically sized items for replacement or alteration of the station will always be needed on a lesser schedule with regards to the stations life expectancy.

Since rockets are necessary to get us into space would it not be more practical to get into building rockets subassemblies or adding to expendable stages in orbit within a hanger near the space station. This would allow for a new mission and continued use of the shuttle that could be used as a way of carrying up the necessary hardware as needed to construct such rockets for use say to the Moon or to Mars.

This only makes good sense if we are to use a reusable Moon Lander as Boeing envisions. we must first learn how to safely transport fuels and develope delivery methods for re-fueling space vehicles once they are on there journey to other places of interest.

Most of all don't waste what research and the material resources that have all ready been paid for as well as built. Recycle what you can into the New Space Exploration program.