Tuesday, July 12, 2005
[This] is such an oxymoron, it's not even funny. Safe, Simple, Soon? Let's examine that claim:
They are proposing a manned launcher based on largely solid motors. Solid rocket motors are basically firecrackers - once they are lit, you cannot turn them off. If you have a problem at any point once they are lit, the best you can do is attempt to get the crew clear (in their concept, using an escape tower), and blow the launcher up. Even using an escape tower is worrying. Launchers such as the Soyuz and Apollo stacks used escape towers, though they were escaping from liquid fueled boosters - which accelerate much slower than solid boosters. It is questionable wether or not a solid-fueled escape tower would accelerate away from a solid-fueled booster quickly enough to matter.
Oh yeah, like it's not rocket science. Making the SRB-based first stage of this system man-rated, meeting all of NASA's new safety requirements would be difficult to say the least. The STS (shuttle) is barely man-rated as is - the SRBs are considered the weak point. Without the ability to jettison the SRBs, the STS would probably never have flown - it would have eliminated a number of abort options.
The only thing near term about it is taking an SRB as the first stage. If you look beyond that, every system is new and unproven. The liquid upper stage is new, based on the [J-2] engine from the Apollo era. The "S" variant underwent ground testing, but had never flown. No J-2 engine has been produced since at least the early 1970s, though some components were used in the design of the RS-2000 engine for the X-33 (which also never flew). It would arguably be better to use upgraded RL-10 engines from the Centaur upper stage, or to base the design on a Russian engine. And again, I can point to the complexity of making a single SRB into a man-rated system.
ATK/Thiokol has constructed this concept (and this site) as a very obvious marketing ploy. What NASA managers should be asking themselves, is that if this was such a great idea, why didn't Thiokol sell it commercially?
[ 7/12/2005 10:13:00 PM ] [