OSP: reliability and survivability

In deciding whether or not to fund NASA's proposed Orbital Space Plane
- a "space taxi" dedicated to crew transport, in contrast to the
current "space truck" - Congressional mavens are making a faulty
assumption. That is that because OSP will be launched on unproven
Delta and Atlas-family rockets, it will be fundamentally no more
reliable than the Shuttle. Because OSP will be costly, it follows that
it makes more sense to upgrade the Shuttle than to build a new
spacecraft.

This is correct on its own narrow terms - rockets tend to explode at
least 1% of the time, despite the best efforts of engineers. However,
putting the OSP on top of the launch stack makes it an inherently
survivable vehicle; rockets can drag the plane clear of a fireball,
and launch debris won't fall onto the vehicle. The OSP becomes its own
ejector seat.

The shuttle, in contrast, can be made more reliable but is inherently
unsurvivable. The Challenger and Columbia incidents only became
disasters because of the Orbiter's placement to one side of the launch
stack. One way round this is to build a B-1B type Crew Escape Module
into the middeck, but this would involve a partial rebuild of the
three remaining Orbiters.

No. Don't upgrade the Shuttle beyond the measures suggested in the
Gehman report. Let's put all our energies into building a reliable,
survivable replacement. Fly the Shuttle only as many times as are
needed to complete the Station, then - ASAP - put these dinosaurs into
mothballs. Time for a change.

Edwin Kite
undergraduate
Cambridge University, UK