Space Shuttle Discovery Faulty FCRS Repair Near Disaster
NASA lead the world into the exploration of space, but behind the scenes, out of the public eye, mistakes, mishaps and failures plagued the space shuttle program. NASA's space shuttle program ended in 2011 and a successful space program in the future depends upon learning from their mistakes.
Space Shuttle Discovery was the third of five orbiters built for NASA's Space Shuttle program.
Three years after space shuttle Columbia broke apart on its return to earth from the International Space Station, NASA prepared to launch a space shuttle for just the second time. The first return to space just one year earlier was a success. If all goes good with this mission the space shuttle program would be cleared to go back to full operation with numerous missions scheduled each year.
Space Shuttle Discovery was on the edge of destruction
On July 4th 2006, American Independence Day, a crew of 7 astronauts are set to be launched in the space shuttle Discovery taking them to the International Space Station. Powered by two solid rocket boosters and 5.6 million pounds of thrust space shuttle Discovery rapidly increases speed. Just 22 seconds into ascent, readings from a pressure transducer literally go off the charts. Over the next 60 seconds pressures hit levels never seen before, and continues to increase until the transducer can no longer read the pressure. The problem occurred in the forward section of the space shuttle in front of the crew module. One minute and 14 seconds into ascent the transducer begins to read the pressure again and within another 60 seconds the readings fell back to normal pressure. Discovery reached orbit with no other issues.
As NASA had never seen this problem before and engineers question if the transducer is bad and giving false readings. If is working properly and the pressure is true than the lives of the astronauts could be in danger.
During ascent of space shutter there is air trying to escape out of the forward reaction control system. The FRCS contains many of the primary thruster used to maneuver Discovery while its in space. It is full of tanks of toxic highly explosive rocket fuel which could be catastrophic when space shuttle Discover returned to earth. A space shuttle has a total of 44 thrusters in its nose and tail.
Space shuttle Discovery's forward reaction control system (FRCS), helps steer the shuttle in orbit
NASA had 13 days to determine if Discovery was safe to return to earth
The transducer could not be fully tested in space, so the NASA team could not eliminate the theory of a faulty transducer. For the safety of the space shuttle crew, NASA had to assume that the pressure readings seen were correct and when comparing to normal launches, the pressure seen while Discovery launched was 3-4 times higher than normal. As the pressure reading were off the carts, engineers did not know how bad the pressure really might be, and made it difficult to know how much damage might have occurred on space shuttle Discovery.
As the shuttle ascends and air in the forward action control section expands, it is normally released though 2 vent ports in the bulkhead. The only way the pressure could be real is if both vent ports were blocked at the same time. Because of the design of the forward action control system, the likelihood that both both vent ports could be block simultaneously seemed almost impossible. Analysis Testing, with extrapolated pressures, showed there would not be damage to the shuttle that would be catastrophic upon re-entry. Mission control monitored the pressure transducer during the 30 minute descent thought the atmosphere, all readings are normal and Discovery lands without incident.
Shocking truth of the massive pressure buildup of the Discovery shuttle launch.
As soon Discovery is in the orbiter processing facility, engineers fully test the pressure transducer and it is conclusively proven that the transducer is working correctly and the pressures were real. NASA was now faced with a mystery that must be resolved before any more space shuttles could be launched.
NASA micro inspection team inspected the vent ports to determine if anything is blocking the ports. The vents were clear, no obstructions were blocking the ports. Near the vent ports, thermal control system blankets cover many surfaces in the FRCS. The thermal control system blankets protect the surfaces of the spacecraft from extreme heat or cold of space. When space shuttle Discovery was originally built, the blankets were installed underneath a PVD drain line. When the blankets are installed correctly it is impossible for them to block the vent ports. Some how the blankets were found installed over the drain lines instead of behind. Testing confirmed that without the drain lines holding the blankets back they could be sucked into the vent ports during ascent creating a intense build up of pressure inside the FRCS. During descent the rush of air into the vent ports would blow the blankets back into their original position.
Why were the TCS blankets installed incorrectly on space shuttle Discovery
An extensive investigation revelled that a series of mistakes spanning several years resulted in the blankets being installed wrong which resulted in the dangerous pressure buildup during launch. The original blankets were installed in 1984 when Discovery was being built, at the time NASA was designing the space shuttles to be operational for only 10 years and the blankets were not ever expected to be removed.
Nearly 20 years later in 2002, during a series of major modifications to space shuttle Discovery, the forward action control system was removed and the blankets were removed for the first time to inspect the structure beneath the blankets. At this time, the new blankets were installed correctly under the drain lines, and in 2005 space shuttle Discovery flew without incident. When discovery returned from that flight, the FRCS was removed again. In 2005 as Discovery flew without incident and the pressure buildup occurred during the 2006 mission.
A cascade of mistakes made in the space shuttle Discovery.
The investigation team revelled that a temporally repair that was cleared for the 2005 mission, had to be permanently fixed and it only could be fixed by removing the FRCS. Before the 2005 mission, a crew cabin leak check was performed to make sure that the fragile atmosphere inside the space craft, that keeps the astronauts alive while in space stays inside and dose not leak out. This time air was leaking out.
The problem was narrowed down to a bulkhead see-though receptacle. The receptacle permits critical wiring to pass though the bulkhead from the crew cabin to the FRCS, and it is supposed to completely seal to prevent air escape for the crew module. It was discovered that that receptacle had not been tightened down enough after a damaged connector pin had been replaced. A high tech space sealant, called room temperature vulcanizing RTV, was applied and stopped the leak. This temporally fix was only cleared by NASA for one space shuttle mission. The replacement of the bulkhead receptacle did not affect the TCS blankets. So when were the blankets installed incorrectly?
Further investigation revelled that when the FRCS was removed from the Discovery shuttle after the 2005 mission. While the FRCS was removed from Discovery, it was transported from the orbiter processing facility to the Hypergolic maintenance facility, because NASA decide to maintenance on 2 fuel lines while the FRCS was removed from Discovery.
To maneuver in space fuel is burned to provide trust, but without oxygen in space, spacecraft must also carry a chemical called oxidizer in order for the fuel to burn. Oxidizer is lethal to humans and when the oxidizer is mixed with water vapor it becomes deadly nitric acid. While doing maintenance on the fuel lines oxidizer escaped, this caused a lot of collateral damage over a wide area of the FRCS. A lot of the tile got eaten up and numerous blankets including the blankets under the drain lines were damaged and had to be replace. The original engineering drawing from 1984 did not clearly indicate that the blankets were supposed to be under the drain line. This is when the thermal control system blankets were installed incorrectly.
An engineering drawing that was not updated, a crew cabin leak that required the removal of the forward reactive control system, a deadly oxidizer leak, and than a wrong thermal control system blanket installation were events that all contributed to the deadly pressures recorded in the 2006 Space shuttle Discovery mission.
This was only just one near disaster with the space shuttle Discovery.