"By day, the engineers work on NASA's new Ares moon rockets. By night, some go undercover to work on a competing design. These dissenting scientists and their backers insist they have created an alternative rocket that would be safer, cheaper and easier to build than the two Ares spacecraft that will replace the space shuttle.

They call their project Jupiter, and like Ares, it's a brainchild of workers at the Marshall Space Flight Center and other NASA facilities. The engineers involved are doing the work on their own time and mostly anonymously, with the help of retirees and other space enthusiasts.

A key Ares project manager dismisses their design as little more than a sketch on a napkin that won't work.

A spokesman for the competing effort, Ross Tierney, said concerned engineers at NASA and some contractors want a review of the Ares plans but can't speak out for fear of being demoted, transferred or fired.

The Jupiter design is being reviewed by a team of 57 volunteer engineers, from line engineers up to NASA middle managers

Page 11 of this Jupiter proposal PDF shows the competing designs. JUPITER seems to use several existing "off the shelf" components. The good news is that JUPITER would supposedly be less expensive and quicker to develop. The bad news is such an approach would cost less and therefore mean less govt jobs and smaller empires for NASA management.