Back to the shuttle. Robot Guy is repeating his prediction that another shuttle launch will not happen. He may be right.
The shuttle was fitted with a new heater meant to prevent ice buildups. However during a fueling test it was found that sensors reading liquid hydrogen levels in the tank were misreading... A potentially dangerous thing if the hydrogen fuel supply runs out in flight while the liquid oxygen is still being supplied to the main shuttle rocket engines. Engineers didn't know if this was a problem with the sensors on the fuel tank, or if it had something to do with the new heater that was installed. The engineers decided to attach it to a new tank under the proviso that another fueling test would be done to determine if the problem was still there. That never happened:
As for the hydrogen sensors, which operated normally the second time around, engineers now believe whatever caused problems during the first tanking test was corrected during extensive post-test troubleshooting.
Translation from NASA speak: "uh we tink de problem is fixed."
NASA managers decided June 6 to forego a third tanking test, saying they were confident the new tank would behave normally during Discovery's countdown. Even though the hydrogen pressurization system begins operating just two minutes before liftoff, the countdown can be safely stopped if any problems develop.
I'm not a flight controls expert, but I'm thinking those engines fire for longer than the two minutes on the launch pad. If the sensors are working intermitently, it's conceivable they could show no problems on the launch pad, but could start malfunctioning after lift off.
Wanting to avoid any such last-minute surprises, however, some engineers argued in favor of a third tanking test to make sure the analysis is correct. But senior managers decided to press ahead. Any serious problems with the tank almost certainly would delay the flight beyond the July 13-31 launch window regardless of when they were discovered.
Reminds me of those Engineers that got the jitters every time they saw ice striking the wings of the Space Shuttle... There is a pretty good chance I would say that the shuttle launch may be delayed again after the meeting on ice debris on June 24. They could make up some excuse about ice debris, but then schedule another tanking test all the same. In Engineering sometimes politics creeps in, and if those critical people in on that ice debris meeting are jittery about those sensors on the external tank, I would bet they would use any opportunity to delay that flight, like for example a few minor sources of ice debris still not wrapped up... Politics, Politics...
The funniy thing about this is that chemical "Rocket Boys" will tell you that the shuttle fuel is cheap. By seperating ou the fuel tank the shuttle design lets us see that chemical fuel is expensive.
ReplyDelete$1,000,000 for the fuel
$70,000,000 for the disposable tank
$+++++ for insurance, this component has destoyed 3 billlion dollars of shuttles.
$????? for souls as engineers appove launches that make them sick.
I know. What's insane though is the actual cost of the liquid fuel is next to nothing compared to the cost of the external tank.
ReplyDeleteThe only way they'll ever get ahead using Chemical Rockets is if they find a way of cheaply storing and using the liquid propellant that doesn't cost 70 times the cost of fuel...
It's either that or NTR.
NTR could reduce the fuel storage needs by 50%.
ReplyDeleteOrion would reduce fuel storage costs three ways, first high ISP cuts fuel needs by 75-90%, second dry fuels are easier to store than liquids and thrid at low altitude NPP ships use a ramjet effect using air as part of the reaction mass.