On Nov 10, 4:41*pm, "Jonathan" wrote:
With the cancellation of Ares1-Y, it looks to be at least
six or eight years before Ares could see a manned flight.
Does it make sense to pursue two different paths to replacing
the shuttle?

I believe that the lack of support for another moon-shot, combined
with the glaring need for lower cost to orbit means this
program is the one that now makes sense.

U.S. Air Force Aims to Launch Space Plane Next Year

"As a reusable space plane, the intent of the craft is to
serve as a testbed for dozens of technologies in airframe,
propulsion and operation, and other items in the hopes
of making space transportation and operations significantly
more affordable. "http://www.space.com/news/090602-x-37b-space-plane.html

s

Executive Summary
NASA'S SPACE SOLAR POWER EXPLORATORY RESEARCH
AND TECHNOLOGY (SERT) PROGRAMhttp://www.nap.edu/openbook.php?record_id=10202&page=1

S PS is terrific. However, what's a really good interplanetary
shuttle (half again or twice the volumetric size) with a nuclear
energy package and those multiple MW ion thrusters, going to cost us?

With a sufficient cache of onboard energy or solar derived energy,
most any fuel or substance can be utilized for ion thrusting,
especially nifty and extremely dense as well as already charged up and
ready to zip out the exhaust would be radon(Rn222) as obtained from a
few kgtonne of radium that could otherwise utilized.

~ BG