Shuttle Launch Pad Damaged During Discovery's Launch 173
pumpkinpuss writes "Launch pad 39A at the Kennedy Space Center suffered unusual damage during the shuttle Discovery's blastoff Saturday. Pictures from a NASA source show buckled concrete and numerous concrete blocks or bricks, presumably from the flame trench, littering a road behind the pad."
how? (Score:1, Interesting)
the rockets are causing the damage, so the damage occurs while the rockets are nearby, right?
so debris is flying thru the air while the shuttle is nearby right?
Re:Thermal Cycling (Score:5, Interesting)
Each batch is specifically formulated to be as identical to the ones before it as possible. While there might me MINOR variances in mix, most of our modern construction absolutely depends on the homogeneousness of the concrete batches. If we really had to deal with widely disparate batches, ntohing large could ever be built, as the overall strength of the finished product could not be counted on. Yes, there are exceptions to this, some of which have caused rather spectacular engineering catastrophes. But the reason they are a big deal is precisely because they are so rare.
Now, if we were still mixing concrete by hand using slave labor like the Romans, then wide variations in concrete batches would be an issue. But we don't. We use complicated mathematics, and specialized weighing and measuring and mixing machines, all tied together by tried and tested computers and software platforms. Concrete hasn't been an issue of "every mixed batch of concrete is different from the last" for at least 50 years, if not longer.
Also, the types of concrete mixed for high-temperature use such as this WOULD be very different than the types mixed for use in bridges.
Concrete used to be my family's business back in the 50's - 70's. I grew up on stories about the concrete business. Not that I would even need that history to understand this though. Don't any of you ever watch the Discovery Channel? Geez.
Re:how? (Score:3, Interesting)
Modern concrete is advanced stuff (Score:5, Interesting)
My friends own a commercial concrete contractor, and current concretes are WAY more advanced than I'd ever have thought.
These days, concrete is like any other advanced man-made composite. The knowledge about cement, water, sand and aggregate types and mixes have been refined to the nth-degree. Then start add-mixing plasticizers, hardners, cure retarders / accelerators, humidity control agents, etc.
The really advanced stuff is like epoxy. Normal concrete is ~3,000psi. My friend was pouring 12,000+ psi concrete for a large structural member in a sub-foundation. The form blew out, and concrete flowed out the hole and setup - within a few hours, even jackhammers became ineffective - it was like drilling steel. They wound up bringing in heavy demo equipment to get out what should have only taken a few men.
Re:Considering the pounding the pads take (Score:1, Interesting)
In an emergency, the launch complex uses an elevator system for quick Shuttle personnel evacuation. Leaving the Shuttle, the crew proceed to an emergency elevator which drops the crew to the ground at speeds up to 55 miles per hour (88 kph).[7] This is a basket on a cable which drops at a steep angle away from the site. From there, the crew board, and drive, a modified M113 Armored Personnel Carrier to a triangular helicopter pad located a couple of hundred feet (60 metres) from the platform and fly away from the complex to safety. As NASA safety rules require all non-crew members to be well away from the pad; the crew must do this without assistance.
That's gotta be a fun training session.
Re:how? (Score:1, Interesting)
The scabbed-away bricks within the flame trench make sense, but the buckled concrete on the back side is what's puzzling. My best guess is vibrations from launch transmitted through the ground, and possibly shifting of the soil around the flame trenches, are the culprit. I'm thinking along the lines of an undetected void forming over the decades in the soil giving way.
I also know NASA recently did some repair work to the crawlerway leading to the launch pad, but I don't know if it included any of the concrete around the flame trench, where we see the buckling in the pictures.
Re:how? Ouch! (Score:3, Interesting)
Oddly, of all the things in the kitchen that make me think "be careful with this thing" -- knives, the stove, garbage disposal -- "measuring cup" was never really on the list until that day.
That said, it'd probably be kinda fun to do in a controlled environment in a MythBusters blowing stuff up kind of way.
In Soviet Russia... (Score:1, Interesting)
On the first flight in 1987 it was to carry Polyus, a 80-ton automatized battle spacestation prototype with 16 propaganda leaflet filled dummy nuclear bomb mines and a recoil-less autocannon onboard. It was to counter the american use of military STS flights and Reagan's SDI "Star Wars" in general, so you can consider it the soviet "Death Star". (In fact the Polyus payload was painted pitch black for radar absorb and visual camouflage, emphasizing its allegiance with the Dark Side.)
Anyhow, the soviets deprived an entire city of 100,000 of running water for one week to fill the vast blast control pond of the N1 launch pad, yet it was not enough. On ignition, one of the support locks failed to open and the rocket tilted 20 degree before tearing itself free. The flight control computer kicked in and the booster righted itself, but the exhaust burned up most tubes and wirings on the lauch tower and melted some of the steel structure.
Eventually the Polyus launch was a failure, as the battle station backfired at 160km altitude due to reversed data from a faulty gyro. The Baikonur launch complex needed one year of rebuild before Energija could fly again, this time hauling the space shuttlesky "Buran", also unmanned. That was a big success, but the USSR soon went bankrupt due to the 20 billion rubles cost of the gigantic booster space programme and many other reasons.
BTW, the Polyus then fell into the southern pacific ocean. In the early 2000s the japanese tried to make a copycat of the CIA's Glomar Explorer scam and built an even larger "ocean bottom driller" something Maru to raise the Poluys wreck for the USA. Of course they failed again for exactly the same reason: press leak.