Larry J made the some comments concerning the currently abandoned X-38/CRV.
I'll respond to some of them:

>It'd be very difficult and expensive to revive any of the Apollo-era hardware.

Except for military RVs, no reentry vehicle (RV) has been subjected to more
theoretical and experimental study than the Apollo CM. The Apollo CM's
aerodynamics were extensively documented (I have copies of many of the
NASA TMs in my office).

>The tools and dies for that hardware were broken up long ago. Furthermore,
>you'd end up reengineering a lot of the systems because those 1960s vintage
>components are no longer available For example, I doubt if any of the logic
>chips and integrated circuits used in Apollo are manufactured any more. You'd
>have to develop all new flight avionics. Furthermore, unless you want to keep
>trained CM pilots on board to handle the reentry, you'll have to develop
>autonomous reentry flight control systems. None of that is cheap.

NASA would reuse the Apollo shape. The thermal protection system (TPS) on
Apollo was rated for return from the Moon and not from low Earth orbit (LEO).
The old AVCO TPS used on Apollo would be replaced with a modern TPS like
SIRCA. The electronics, etc. used on the Apollo CM are utterly obsolete and
inappropriate for return from LEO. The type of flight computers used in the
Shuttle OV (Rad hard 80386 processors) would be more appropriate. Although
they had the option, the astronauts didn't really fly the Apollo CM in the
atmosphere. The primitive on-board computer handled the roll modulation to
keep the CM within its entry corridor. In the event of a computer
malfunction, the CM pilot did have the option of controlling the CM during
reentry by either keeping one of the lines etched in his window on the
horizon or following the 8-ball on his console. A high lift hypersonic
vehicle is much harder to fly. A big problem is keeping it in the atmosphere
(they tend to skip in-and-out much like a flat stone skipping across the
surface of a lake). Characterizing the aerodynamics of a high lift RV is not
easy (I've done it).

>The CRV is designed espressly for the escape mission. All of its systems are
>designed for long-term on-orbit storage.

So was the Apollo CM for use on the Skylab station. It's a proven performer.

>The flight control system is simplified to the point that a crew can pile
>in, close the hatch, strap in and press a button to come home.

The flight control system for a high lift reentry vehicle would be much
more squirrely than a low lift / high drag system like the Apollo CM. If
anything, it would be easier to have a fully automated system with a CM
than a high lift RV like X-38.

>Given the ISS's 51 degree inclination, there are a lot of inhospitable
>places where an escape craft might end up landing. Good cross-range
>capability might make the difference from coming down in a jungle or coming
>down near a small city.

It takes 90 minutes to complete one orbit in LEO. During that 90 minutes
the orbit would cross the equator twice. The rescue capsule could have
a flat display terminal showing the ground track and where it would land
if the retro-rocket where immediately fired. The astronauts would simply
wait until they saw a nice spot and then press the button.

>Furthermore, Apollo capsules were wonderful spacecraft but lousy boats.
>A high percentage of the time, they flipped inverted after hitting the water.

Do you think the X-38 would make a better boat? I suspect it also inverts
while floating.

>Also, the CRV parafoil allows the CRV to land just about anywhere from a
>small town airport to a clearing. Apollo capsules had provisions to come down
>on land but it would've been a very rough landing.

The parafoil provides lift thus providing a softer landing and could also
be used on an Apollo CM. However the parafoil is a mixed blessing. What
happens if the vehicle lands in a forest or an alpine valley. A parachute
with an airbag (pop the heatshield off like they did with the Mercury capsule)
probably provides a softer landing.

Kim Keller also made some comments which I'll respond to:

>Low g-load during reentry, especially critical in many medical emergencies
>or for a crew that has been in micro-g for a few months. Capsules, even those
>with a limited lift capability (like Apollo), will subject the occupants to a
>much higher g-load.

This is a good counter argument. However the X-38 would still have a fairly
hard landing. Also most of the escape scenarios don't involve astronauts
with broken limbs (how do you break a leg in zero-G?). Typical escape
scenarios would involve things like on-board fire/explosion, total electrical
failure, meteorite impact, etc. It could be counter argued that one expensive
escape vehicle at one end of the ISS is inferior to two cheap escape vehicles
at opposite ends of the ISS. It's easy to imagine the astronauts wanting to
get out of the ISS in a hurry. Two vehicles with two escape hatches would
greatly increases their speed of escape.

>Second, as Larry pointed out, an automated approach is preferred because it
>doesn't require pilot training (what if your pilot is the one who just got hit
>with serious amps at 120VAC?); anyone can hop in and press the button.

Again it's probably easier to automate a low lift entry vehicle than a high
lift one. Remember the escape pod that C3PO and R2D2 used to flee from the
embassy ship in the original episode of Star Wars? That's the sort of
vehicle that I'm thinking of (but without the big windows).

Gary