The mission began with a little-known smaller incident: during the second-stage boost, the center (inboard) engine shut down two minutes early. The four outboard engines burned longer to compensate, and the vehicle continued to a successful orbit. The shutdown was determined to be due to dangerous pogo oscillations that threatened to tear the second stage apart. The engine experienced 68g vibrations at 16 hertz, flexing the thrust frame by 3 inches (76 mm).[7] The engine shutdown was triggered by sensed thrust chamber pressure fluctuations.[8] Smaller pogo oscillations had been seen on previous Titan and Saturn flights (notably Apollo 6), but on Apollo 13 they were amplified by an unexpected interaction with turbopump cavitation.[9] Later missions implemented anti-pogo modifications that had been under development. These included addition of a helium gas reservoir to the center engine liquid oxygen line to dampen pressure oscillations, an automatic cutoff as a backup, and simplification of the propellant valves of all five second-stage engines.
oxygen tank incidentExplosion “Houston, we’ve had a problem.”
Swigert and Lovell reporting the incident on April 14, 1970
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The Term Paper on Algorithmic Aero Engine Life Usage Monitoring Based on Reference Analysis of Design Mission
Algorithmic Aero Engine Life Usage Monitoring Based on Reference Analysis of Design Mission _________________________________________________ MANFRED KOEHL 1 ABSTRACT Fracture critical areas in an aero engine are usually located in fast rotating com- ponents which are exposed to high temperatures. Therefore, a direct local meas- urement of damage related parameters like strains and temperatures is ...
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En route to the Moon, approximately 200,000 miles (320,000 km) from Earth, Mission Control asked Swigert to turn on the hydrogen and oxygen tank stirring fans, which were designed to destratify the cryogenic contents and increase the accuracy of their quantity readings. Approximately 93 seconds later the astronauts heard a “loud bang”, accompanied by fluctuations in electrical power and firing of the attitude control thrusters.[6] The crew initially thought that a meteoroid might have struck the lunar module (LM).
Overall view of the Mission Operations Control Room during Apollo 13’s fourth television transmission, on the evening of April 13, 1970. Astronaut Fred Haise, Jr., lunar module pilot, is seen on the screen.In fact, the number 2 oxygen tank, one of two in the Service Module (SM), had exploded.[10] Damaged Teflon insulation on the wires to the stirring fan inside oxygen tank 2 allowed the wires to short-circuit and ignite this insulation. The resulting fire rapidly increased pressure beyond its 1,000 pounds per square inch (6.9 MPa) limit and the tank dome failed, filling the fuel cell bay (Sector 4) with rapidly expanding gaseous oxygen and combustion products. It is also possible some combustion occurred of the Mylar/Kapton thermal insulation material used to line the oxygen shelf compartment in this bay.[11]
Apollo 13’s damaged Service Module, as photographed from the Command Module after being jettisonedThe resulting pressure inside the compartment popped the bolts attaching the 13-foot Sector 4 outer aluminum skin panel, which as it blew off probably caused minor damage to the nearby high-gain S-band antenna used for translunar communications. Communications and telemetry to Earth were lost for 1.8 seconds, until the system automatically corrected by switching the antenna from narrow-band to wide-band mode.
The Term Paper on Lunar Module Tank Crew Apollo
... were also asked to stir the liquid oxygen and liquid hydrogen in the service module tanks in order to ensure proper feed to ... no apparent damage to the tank. After the vacuum pump modifications, the tank was installed in service module 109 for the flight of Apollo 13. ... said. "It's a gas of some sort." It was oxygen. The number 2 tank had ruptured. Two of the ships three fuel cell ...
Mechanical shock forced the oxygen valves closed on the number 1 and number 3 fuel cells, which left them operating for only about three minutes on the oxygen in the feed lines. The shock also either partially ruptured a line from the number 1 oxygen tank, or caused its check or relief valve to leak, causing its contents to leak out into space over the next 130 minutes, entirely depleting the SM’s oxygen supply.[11]
Because the fuel cells combined hydrogen and oxygen to generate electricity and water, the remaining fuel cell number 2 finally shut down and left the Command Module (CM) on limited-duration battery power. The crew was forced to shut down the CM completely and to use the LM as a “lifeboat”.[12] This had been suggested during an earlier training simulation but had not been considered a likely scenario.[13] Without the LM, the accident would certainly have been fatal.[14]
Crew survival and return journey
The circumlunar trajectory followed by Apollo 13. At the time of the accident, the Moon’s gravitational pull on Apollo 13 was greater than the Earth’s.
The Direct Abort return trajectory was not viable by this time.The damage to the Service Module made safe return from a lunar landing impossible, so Lead Flight Director Gene Kranz immediately aborted the mission. The existing abort plans, first drawn up in 1966, were evaluated; the quickest was a Direct Abort trajectory, which required using the Service Module engine to achieve a large change in velocity to essentially reverse the direction of the craft. Though a successful firing would have landed the crew days earlier in the Indian Ocean, it was highly impractical for the following reasons:
It was practical only in an earlier stage of the mission, before the craft entered the Moon’s gravitational sphere of influence, which Apollo 13 had already done at the time of the accident.
There was no practical way to get electrical power for the guidance computer or oxygen needed to execute a burn with the engine.
It was feared the engine might have been damaged when the O2 tank had exploded, preventing the engine from being fired safely.
For these reasons, Kranz and Flight Director Chris Kraft chose the circumlunar “free return” option, using the Moon’s gravity to return the ship to Earth, with an acceleration burn shortly after pericynthion (closest approach to the Moon, “PC+2 burn”) to help speed the return. However, Apollo 13 had left its initial free return trajectory earlier in the mission, as required for the planned lunar landing at Fra Mauro. Therefore, the first order of business was to re-establish the free return trajectory with a small burn of the LM descent propulsion system. The descent engine was used again for the PC+2 burn. One more descent engine burn was later required for a minor course correction.
The Term Paper on Oxygen and Trees
Trees occupy an important place in the life of man. The trees provide us flowers, fruits, fodder for animals, wood for fire and furniture and provide cool shadow from scorching sun. They give us so many such good things and yet expect nothing in return. Trees give us fruits for food and flowers for pleasure. They provide us timber (wood) for building our houses and making furniture. They provide ...
Astronaut John L. Swigert, at right, holds the “mailbox” rig improvised to adapt the Command Module’s square carbon dioxide scrubber cartridges to fit the Lunar Module, which took a round cartridgeConsiderable ingenuity under extreme pressure was required from the crew, flight controllers, and support personnel for the safe return. The developing drama was shown on television.[15] Because electrical power was severely limited, no more live TV broadcasts were made; TV commentators used models and animated footage as illustrations. Low power levels made even voice communications difficult.
The LM “lifeboat” consumables were intended to sustain two people for a day and a half, not three people for four days. Oxygen was the least critical consumable because the LM carried enough to repressurize the LM after each surface EVA. Unlike the CSM, which was powered by fuel cells that produced water as a byproduct, the LM was powered by silver-zinc batteries, so electrical power and water (used for equipment cooling as well as drinking) were critical consumables. To keep the LM life support and communication systems operational until re-entry, the LM was powered down to the lowest levels possible.
The Apollo 13 lunar module Aquarius is jettisoned above the Earth after serving as a lifeboat for four days. It reentered Earth’s atmosphere over Fiji and burned up.Limited available lithium hydroxide (LiOH) for removing carbon dioxide presented a serious problem. The LM’s internal stock of LiOH canisters was not sufficient to support the crew until return, and the remainder was stored in the descent stage, out of reach. The CM had an adequate supply of canisters, but these were incompatible with the LM. Engineers on the ground improvised a way to join the cube-shaped CM canisters to the LM’s cylindrical canister-sockets by drawing air through them with a suit return hose. The astronauts called the jury-rigged device “the mailbox”.[16]
The Essay on Power Of Opinion Success Game Support
The Power of Opinion Confidence is a key component in the development of success. In order to reach this stability one must be a recipient of encouragement and upholding. This support creates an individuality and esteem for success. For example, in my experiences with females I have come to a vague realization that they feed off of encouragement. It seems like the focus of most of the girls that I ...
Another problem to be solved for a safe return was accomplishing a complete power-up from scratch of the completely shut-down Command Module, something never intended to be done in-flight. Flight controller John Aaron, with the support of grounded astronaut Mattingly and many engineers and designers, had to invent a new protocol to do this with the ship’s limited power supply and time factor.[17][18] This was further complicated by the fact that the reduced power levels in the LM caused internal temperatures to drop considerably. The un-powered CM got so cold that water began to condense on solid surfaces, causing concern that this might short out electrical systems when it was reactivated. This turned out not to be a problem, partly because of the extensive electrical insulation improvements instituted after the Apollo 1 fire.[19]
Re-entry and splashdown
The crew of Apollo 13 on board the USS Iwo Jima following splashdownAs Apollo 13 neared Earth, the crew first jettisoned the Service Module so pictures could be taken for later analysis. It was then that the crew were surprised to see for the first time that the Sector 4 panel had been blown off. According to the analysts, these pictures also showed the antenna damage and possibly an upward tilt to the fuel cell shelf above the oxygen tank compartment.
Apollo 13 splashes down in the South Pacific on April 17, 1970Finally, the crew jettisoned the Lunar Module Aquarius, leaving the Command Module Odyssey to begin its lone re-entry through the atmosphere. The re-entry on a lunar mission normally was accompanied by four minutes of communications blackout caused by ionization of the air around the Command Module. The possibility of heat shield damage from the O2 tank rupture heightened the tension of the blackout period, which took 33 seconds longer than normal.
However, Odyssey regained radio contact and splashed down safely in the South Pacific Ocean, 21°38′24″S 165°21′42″W / 21.64°S 165.36167°W / -21.64; -165.36167 (Apollo 13 splashdown), southeast of American Samoa and 6.5 km (4.0 mi) from the recovery ship, USS Iwo Jima. The crew was in good condition except for Haise, who was suffering from a serious urinary tract infection because of insufficient water intake. To avoid altering the trajectory of the spacecraft, the crew had been instructed to temporarily stop urine dumps. A misunderstanding prompted the crew to store all urine for the rest of the flight.[20]
The Essay on Solar Power Assisted Electric Scooter
INTRODUCTION “Because we are now running out of gas and oil, we must prepare quickly for a third change, to strict conservation and to the use of coal and permanent renewable energy sources, like solar power.” – JIMMY CARTER, televised speech, Apr. 18, 1977 In times such as today, cumulative solar energy production accounts for less than 0.01% of total Global Primary Energy demand. And the ...
