OK, one more before I head to the airport. Leonard David reports that Burt Rutan and Richard Branson have a new spaceship company.

Sounds like a creative way to get around ITAR to me...

A sincere hooray for Scaled Composites!

Regarding the debate about whether or not a Shuttle Orbiter can land on autopilot without a human pilot: they sure can do so, with only a few flight control system modifications, such as removing the requirement for human pilot input to "unsafe" the landing gear and allow the wheels to be lowered.

Operating Shuttles to deliver cargo without humans aboard is an excellent end-of-life plan for the three remaining Orbiters, in my opinion.

The current Discovery mission will undoubtedly return with all eight astronauts aboard. Why? Two reasons. First, as Rand and several otehrs have said, damage to the Discovery's thermal tiles is probably no worse than damage suffered by Shuttles on many previous round-trip missions.

Furthermore, if you're Dr. Griffin and you suspect all the External Tanks may be bad and you have to launch a rescue Shuttle within the next few months and there's no time to design and build an imporved ET during that time, you'd worry that you might end up with TWO SHUTTLES STRANDED at the ISS. Nope, here's no doubt about it, the Discovery's crew is coming back to Earth on the Discovery.

Lastly a question for other engineers: would it be altogether silly to to try to Band-Aid STS External Tanks by wrapping them, literally, in a stout cloth mesh?

I think they sell stuff like that at Home Depot. Green, sort of like one might use to make a homemade volleyball net.

Dave: "Lastly a question for other engineers: would it be altogether silly to to try to Band-Aid STS External Tanks by wrapping them, literally, in a stout cloth mesh?

I think they sell stuff like that at Home Depot. Green, sort of like one might use to make a homemade volleyball net."

I've been thinking along the same lines, although something a bit more exotic than what you would find at Home Depot. ;-)

Perhaps a 3-4 mm mesh of a stout kevlar thread, with a stouter thread spaced every 100 mm or so. Bond this over the foam, and only on the side of the tank where the Orbiter mounts. And extend only down to parallel to the aft end of the Orbiter. I wonder if this might add the needed extra margin of strength to the foam without a huge increase in weight?

According to this article article it seems the external tank is now some 17,000 lbs. lighter than the first external tanks used in the early '80s. Seems that some compromise on payload capacity could be made to ensure the damn foam doesn't shed. Of course, as far as I know perhaps such a trade-off was already made over the last two years and the stuff still came off.

For the first few flights the tanks were painted with a white latex paint that made the tanks weigh 600 lbs. heavier. Seems that perhaps going back to some type of similar paint could serve three purposes:

1. Provide additional mechanical support to the foam from the outside. A paint could be selected or formulated to provide such strength.

2. Provide an aerodynamically smoother surface over the foam so it is less likely to be peeled off by the supersonic slip stream.

3. Prevent moisture from the air and rain from penetrating the foam while in storage and on the pad. It seems that freezing moisture could easily compromising foam strength and cohesion. If I recall, the Columbia remained on the pad a few weeks longer than normal and was subjected to a lot more rain than normal.

One other thought, I assume the external tank will contract when filled with liquid fuel because of the extremely cold temperature. If the foam is brittle and doesn't contract in the same manner as the external tank it could weaken the bond of the foam to the tank making it more prone to peeling when under aerodynamic stress.

Just a few additional thoughts.

And to stay on topic, another hooray for Scaled Composites.

5 segment SRBs might compensate for a heavier tank.

I don't think 600 pounds of latex paint require an SRB redesign.

Paint won't be enough to keep the foam on, or so I read elsewhere.

Perhaps the kevlar mesh bonded in place by a epoxy paint?

But surely NASA has thought of these ideas.... right? ;-)