Author Topic: Discovery STS-26 – The Dream is Alive  (Read 116421 times)

Offline Ares67

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Discovery STS-26 – The Dream is Alive
« on: 06/20/2012 09:06 AM »
The road so far

RTF 1986 – Find Your Way Back

http://forum.nasaspaceflight.com/index.php?topic=28811.0   

RTF 1987 – It’s a Long Way…

http://forum.nasaspaceflight.com/index.php?topic=28914.0

RTF 1988 – The Journey Continues

http://forum.nasaspaceflight.com/index.php?topic=29072.0

Discovery was selected as the Space Shuttle for the STS-26 mission in 1986. At the time of the 51-L accident, Discovery was in temporary storage in the KSC Vehicle Assembly Building awaiting transfer to the Orbiter Processing Facility for preparation for the first shuttle flight from Vandenberg Air Force Base, CA, scheduled for later that year. Discovery last flew in August 1985 on shuttle mission 51-I, the orbiter's sixth flight since it joined the fleet in November 1983.

In January 1986, the shuttle Atlantis was in the OPF, prepared for the Galileo mission and ready to be mated to the boosters and tank in the VAB. The orbiter Columbia had just completed the 61-C mission a few weeks prior to the accident and was also in the OPF undergoing post-flight deconfiguration. Various shuttle manifest options were being considered, and it was determined that Atlantis would be rolled out to Launch Pad 39-B for fit checks of new weather protection modifications and for an emergency egress exercise and a countdown demonstration test. During that year it also was decided that Columbia would be flown to Vandenberg for fit checks. Discovery was then selected for the STS-26 mission.

Discovery was moved from the VAB High Bay 2, where it was in temporary storage, into the OPF the last week of June 1986. Power-up modifications were active on the orbiter's systems until mid-September 1986 when Discovery was transferred to the VAB while facility modifications were performed in Bay 1 of the OPF. Discovery was moved back into the OPF bay 1 on Oct. 30, 1987, a milestone that initiated an extensive modification and processing flow to ready the vehicle for flight. The hiatus in launching offered an opportunity to "tune-up" and fully check out all of the orbiter's systems and treat the orbiter as if it was a new vehicle. Most of the orbiter's major systems and components were removed and sent to the respective vendors for modifications or to be rebuilt.

After an extensive powered-down period of 6 months, which began in February 1987, Discovery's systems were awakened when power surged through its electrical systems on Aug. 3, 1987. Discovery remained in the OPF while workers implemented over 200 modifications and outfitted the payload bay for the Tracking and Data Relay Satellite. Flight processing began in mid-September during which the major components of the vehicle were reinstalled and checked out, including the main engines, the right and left hand orbital maneuvering system pods and the forward reaction control system.

In January 1988, Discovery's three main engines arrived at KSC and were installed. Engine 2019 arrived Jan. 6, 1988, and was installed in the number one position Jan. 10. Engine 2022 arrived Jan. 15 and was installed in the number 2 position Jan. 24. Engine 2028 arrived Jan. 21 and was installed in the number 3 position also on Jan. 24. The redesigned solid rocket motor segments began arriving at KSC March 1, and the first segment, the left aft booster, was stacked on Mobile Launcher 2 in VAB High Bay 3 on March 29. Technicians started with the left aft booster and continued stacking the four left hand segments before beginning the right hand segments on May 5. The forward assemblies/nose cones were attached May 27 and 28. The SRB field joints were closed out prior to mating the external tank to the boosters on June 10. An interface test between the boosters and tank was conducted a few days later to verify the connections.

The OASIS payload was installed in Discovery's payload bay on April 19. The TDRS arrived at the Vertical Processing Facility on May 16, and its Inertial Upper Stage arrived May 24. The TDRS/IUS mechanical mating was accomplished on May 31.

Discovery was moved from the OPF to the VAB June 21, where it was mated to the external tank and Solid Rocket Boosters. A Shuttle Interface Test was conducted shortly after the mate to check out the mechanical and electrical connections between the various elements of the shuttle vehicle and the function of the onboard flight systems. The assembled Space Shuttle vehicle aboard its mobile launcher platform was rolled out of the VAB on July 4, 4.2 miles to Launch Pad 39-B for a few major tests and final launch preparations.

A few days after Discovery's orbital maneuvering system pods were loaded with hypergolic propellants, a tiny leak was detected in the left pod (June 14). Through the use of a small, snake-like, fiber optics television camera, called a Cobra boroscope, workers pinpointed the leak to a dynatube fitting in the vent line for the reaction control system nitrogen tetroxide storage tank, located in the top of the OMS pod. The tiny leak was stabilized and controlled by "pulse-purging" the tank with helium - an inert gas. Pulse-purge is an automatic method of maintaining a certain amount of helium in the tank. In addition, console operators in the Launch Control Center firing room monitored the tank for any change that may have required immediate attention. It was determined that the leak would not affect the scheduled Wet Countdown Demonstration Test and the Flight Readiness Firing and repair was delayed until after these important tests.

The WCDDT, in which the external tank was loaded with liquid oxygen and liquid hydrogen, was conducted August 1. A few problems with ground support equipment resulted in unplanned holds during the course of the countdown. A leak in the hydrogen umbilical connection at the shuttle tail service mast developed while liquid hydrogen was being loaded into the external tank. Engineers traced the leak to a pressure monitoring connector. During the WCDDT, the leak developed again. The test was completed with the liquid hydrogen tank partially full and the special tanking tests were deleted. Seals in the 8-inch fill line in the tail service mast were replaced and leak checked prior to the FRF. In addition, the loading pumps in the liquid oxygen storage farm were not functioning properly. The pumps and their associated motors were repaired.

After an aborted first attempt, the 22-second flight readiness firing of Discovery's main engines was conducted August 10. The first FRF attempt was halted inside the T-10 second mark due to a sluggish fuel bleed valve on the number 2 main engine. This valve was replaced prior to the FRF. This firing verified that the entire shuttle system - including launch equipment, flight hardware and the launch team – were ready for flight. With over 700 pieces of instrumentation installed on the vehicle elements and launch pad, the test provided engineers with valuable data, including characteristics of the redesigned Solid Rocket Boosters.

After the test, a team of Rockwell technicians began repairs to the OMS pod leak. Four holes were cut into two bulkheads with an air powered router on Aug. 17. A metal "clamshell" device was bolted around the leaking dynatube fitting. The clamshell was filled with furmanite - a dark thick material which consists of graphite, silicon and heavy grease and glass fiber. After an initial leak check was successfully performed, covers were bolted over the holes August 19, and the tank was pressurized to monitor any decay. No leakage or decay in pressure was noted and the fix was deemed a success.

TDRS-C and its IUS upper stage were transferred from the VPF to Launch Pad 39-B on August 15. The payload was installed into Discovery's payload bay August 29. A Countdown Demonstration Test, a dress rehearsal for the STS-26 flight crew and KSC launch team, designed as a practice countdown for the launch, was conducted on September 8. Launch preparations during the last two weeks prior to launch countdown included final vehicle ordnance activities, such as power-on stray-voltage checks and resistance checks of firing circuits; loading the fuel cell storage tanks; pressurizing the hypergolic propellant tanks aboard the vehicle; final payload closeouts; and a final functional check of the range safety and SRB ignition, safe and arm devices.

The launch countdown was picked up at the T-minus-43 hour mark on September 26, leading up to the first shuttle liftoff since January 28, 1986. The STS-26 launch will be conducted by a joint NASA/industry team from Firing Room 1 in the Launch Control Center. (Source: STS-26 Press Kit – edited)

Now
« Last Edit: 06/20/2012 09:20 AM by Ares67 »

Offline Ares67

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Re: Discovery STS-26 – The Dream is Alive
« Reply #1 on: 06/20/2012 09:09 AM »

Offline Ares67

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Re: Discovery STS-26 – The Dream is Alive
« Reply #2 on: 06/20/2012 09:12 AM »
Tonight the rain is falling
Full of memories of people and places
And while the past is calling
In my fantasy I remember their faces

The hopes we had were much too high
Way out of reach but we have to try
The game will never be over
Because we're keeping the dream alive

(Münchener Freiheit – Fantasy / Keeping the Dream Alive, 1986)

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Re: Discovery STS-26 – The Dream is Alive
« Reply #3 on: 06/20/2012 09:13 AM »
Let’s Fly!

The sun-bleached wheels of the Conestoga wagons dig tracks into the hot sand. The wagon train circles and comes to a rest. The men and women climb out and gaze skyward.

Ivan Kincheloe – and the other test pilots in their jackets of leather stride down the long runway and pause at the edge of the sun-seared tarmac.

Grissom, White and Chaffee – and the other astronauts – climb to the top of the rusted blockhouse of Pad 34 and wait.

The waterfall at the base of the pad begins. Sparks fly, clearing hydrogen gas. The engine bells, licking nearly invisible tongues of flame, shutter a moment and snap into position. The twin white towers erupt with a volcanic force. The shuttle is instantly cut loose and rises above Pad 39B.

The shuttle rolls on its back in the clear Florida sky. It is Challenger. It rides its smoke pillar in front of the Conestogas, which Grissom and Kincheloe and all the rest watch.

The first 73 seconds of flight belong to Challenger – it is Challenger, the past. Then the wagons fade, Grissom and the others fade, like photographs left too long in the sun.

SRB sep – and the orbiter, clinging like a moth to the fat orange External Tank, climbs out ahead. It is Discovery, it is the future.

And from orbit above, Freedom Station watches the shuttle ride to orbit. From the Moon, the new Tranquility Base listens. From Mars, the red sands await.

Discovery reaches safe orbit with eyes on the future. The 21st Century begins here. Discovery is the first of many entrance tests into the next Millennium. More is riding in the shuttle than five astronauts and a communications satellite.

What happens to the Space Shuttle will happen to ourselves as a nation. We will either approach the 21st century bold and growing, confident of our abilities to compete in the world – or we will retreat from the heavens and from the leading edge of humanity’s advancement.

If you want to know what is happening to the United States, check the skies. Is Discovery up there?

Rick Hauck, Discovery’s commander, has said, “We clearly could not afford to lose another vehicle, much less another crew, both from an emotional and the economic impact it would have.”

Nor can we afford to sit on the ground, uncertain if we have the technological capability to compete in the 21st Century. We need to leave our safe homes and look to the skies again. We need to learn to take risks again. Each shuttle flight for the next few years will be a test of our courage, a test of our worthiness to participate in the 21st Century.

It’s time to test ourselves as a people. It’s time to light this candle and go fly!

(Editorial by Dixon P. Otto, Countdown “STS-26 Preview Issue”, October 1988)

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Re: Discovery STS-26 – The Dream is Alive
« Reply #4 on: 06/20/2012 09:20 AM »
STS-26 -- THE RETURN TO FLIGHT

The Space Shuttle will return to flight when the orbiter Discovery is launched on its seventh flight now scheduled for no earlier than late September, 1988. STS-26 will have as its primary payload the Tracking and Data Relay Satellite (TDRS-C) that will complete the constellation needed to communicate with spacecraft in low-Earth orbit. TDRS-B was lost in the 51-L Challenger accident. A third TDRS will be launched on a later shuttle mission to replace the first TDRS, which then will be used as an on-orbit spare in the event that one of the two operational satellites fails.

Commander of the five-man crew is Frederick H. (Rick) Hauck, Captain, USN, a veteran of two shuttle missions -- 51-A and STS-7. Pilot for the mission is Richard O. (Dick) Covey, a Colonel in the USAF and veteran of the 51-I shuttle mission. Three mission specialists are assigned to the crew: John M. (Mike) Lounge, David C. Hilmers, Lt. Colonel, USMC, and George D. (Pinky) Nelson. STS-26 will be the second flight for Lounge and Hilmers who previously flew on missions 51-I and 51-J, respectively. Nelson has flown two previous shuttle missions -- 41-C and 61-C.

While NASA does not discuss their crew selection criteria, the qualifications needed for STS-26 are easily apparent: NASA filled the crew list with seasoned veterans possessing proven records of success. This crew will become only the third all-veteran crew NASA has placed in space. The only other two all-veteran crews were the Apollo 10 (Thomas P. Stafford, John W. Young and Eugene A. Cernan) and Apollo 11 (Neil A. Armstrong, Michael Collins and Edwin “Buzz” Aldrin, Jr.). STS-26’s five astronauts represent a total of over 1091 hours in space and have been present on one-fourth of the successful shuttle missions.

TDRS-C will be deployed 6 hours, 13 minutes into the mission on flight day one. An Air Force-developed Inertial Upper Stage will boost the TDRS to geosynchronous orbit. The Orbiter Experiments Program Autonomous Supporting Instrumentation System (OASIS) will be flown on STS-26 to record environmental data in the orbiter payload bay during STS flight phases. In addition to TDRS-C and OASIS, Discovery will carry 11 secondary payloads, including two student experiments, involving microgravity research, materials processing and electrical storm studies. After landing at Edwards, Discovery will be towed to the NASA Ames-Dryden Flight Research Facility, hoisted atop the Shuttle Carrier Aircraft and ferried back to the Kennedy Space Center to begin processing for its next flight. (Source: STS-26 Press Kit and Countdown, STS-26 Preview Edition, October 1988 - edited)

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Re: Discovery STS-26 – The Dream is Alive
« Reply #5 on: 06/20/2012 09:21 AM »

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Re: Discovery STS-26 – The Dream is Alive
« Reply #6 on: 06/20/2012 09:24 AM »
A Simple Mission Of Great Importance

The 26th flight of the Space Transportation System is a simple, easy one. The flight, with only five astronauts, will only last four days. Nothing is new about the payload. The Tracking and Data Relay Satellite (TDRS), which forms the only payload, cannot be called a major new event, since the same type of satellite first flew on the shuttle in 1983. STS-26 is a milk run. By 1985 shuttle standards, it does not rate a yawn. Even mission commander Rick Hauck admits the flight is “a relatively less complicated mission than some of the previous ones.” – But this is 1988. This is the third year on the shuttle flight hiatus. This is the flight to carry the image of the shuttle beyond 73 seconds after lift-off.

“It’s appropriate that when we are thrown from the horse, we trot before we gallop,” Hauck said.

While the payload is not of the new type and the flight is the fourth shortest shuttle mission, something will be new in the skies: Discovery will be flying with over 200 changes. “This is going to be a test flight. Although I’ve said in the past that this is the safest fight we’ve ever flown, that does not discount the fact that we’ve made an awful lot of changes to virtually every system of the orbiter,” Hauck said.

“I have a great deal of confidence in the machine,” said STS-26 pilot Richard Covey. The improvement we’ve made in the orbiter should make it safer. At the same time, the thing that we don’t forget as a crew is that a lot of those changes have not been flight tested yet. Our mission, indeed, is a flight test of those changes. There’s always a risk involved in the first time you fly any piece of equipment that’s been changed.”

Hauck said he expects something, however minor, to fail along the way. “You always run the risk of making something that’s adequate worse by trying to make it better,” he said. “I don’t think we’ve done that in any case, but quite often you’ll find in testing a system that you’ve modified, you’ve made points towards something that maybe won’t work quite the way you expected it would.”

Discovery’s four-day-long mission, spread out over five Earth days, should proceed much like the flights of old, despite all the hardware changes and the lighter schedule. “I cannot think of a single significant change we have made to operations, “ said STS-26 lead flight director, Larry Bourgeois. “I would say we’ve added mor rigor to the way we do business, that’s probably the most significant change.” Bourgeois does not view the mission as a test flight. “I consider it a Return to Flight… but to me, it’s pretty much business as usual as an operator,” he said.

Bourgeois does not consider STS-26 a “short” mission. “The flight is as long as it needs to be to accomplish the objectives we have set for it,” he said. “When we fly, we prefer not to stay on orbit unless we have things to do.” – While the flight should proceed like a normal operational one, Bourgeois admitted the controller’s feelings will not be routine. “We’re all going to be just like for the first flight of the shuttle. We’re going to have those sweaty palms and the knot in your stomach – just like everybody else will. But we’ve got all the confidence in the world that we’re not going to have a problem,” he said. (Countdown, STS-26 Preview Issue, October 1988 – edited)

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Re: Discovery STS-26 – The Dream is Alive
« Reply #7 on: 06/20/2012 09:28 AM »
MAJOR ORBITER MODIFICATIONS

More than 100 mandatory modifications to the orbiter Discovery were completed before returning to flight. Major modifications include:

- Brake Improvements -- This included changes to eliminate mechanical and thermally-induced brake damage, improve steering margin and reduce the effects of tire damage or failure. Modifications for first flight are the thicker stators, stiffened main landing gear axles, tire pressure monitoring and anti-skid avionics.

- 17-Inch Disconnect -- A positive hold-open latch design feature for the main propulsion system disconnect valves between the orbiter and the external tank (ET) was developed to ensure that the valve remains open during powered flight until nominal ET separation is initiated.

- Reaction Control System Engines -- The RCS engines provide on-orbit attitude control and have been modified to turn off automatically in the event any combustion instability were to cause chamber wall burnthrough.

- Thermal Protection System -- The TPS was improved in areas on the orbiter in the wing elevon cove region, nose landing gear door, lower wing surface trailing edge and elevon leading edge.

- Auxiliary Power Unit -- An electrical interlock has been added to the APU tank shutoff valves to preclude electrical failures that could overheat the valves and cause decomposition of the fuel (hydrazine).

- Orbital Maneuvering System -- To prevent development of leaks as a result of improper manufacturing processes, bellows in critical OMS propellant line valves have been replaced.

- Crew Escape System -- A pyrotechnically jettisoned side hatch, crew parachutes and survival gear and a curved telescoping pole to aid the crew in clearing the wing, have been added to give a bail-out capability in the event of a problem where runway landing is not possible. An egress slide has been added to facilitate rapid post-landing egress from the vehicle under emergency conditions. (Source: STS-26 Press Kit)

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Re: Discovery STS-26 – The Dream is Alive
« Reply #8 on: 06/20/2012 09:31 AM »
SOLID ROCKET MOTOR REDESIGN

On June 13, 1986, the President directed NASA to implement the recommendations of the Presidential Commission on the Space Shuttle Challenger Accident. As part of satisfying those recommendations, NASA developed a plan to provide a redesigned solid rocket motor (SRM). The primary objective of the redesign effort was to provide an SRM that is safe to fly. A secondary objective was to minimize the impact on the launch schedule by using existing hardware, to the extent practical, without compromising safety.

A redesign team was established which included participation from Marshall Space Flight Center; Morton Thiokol, NASA's prime contractor for the SRM; other NASA centers; contractors and experts from outside NASA. All aspects of the existing SRM were assessed. Design changes were deemed necessary in the field joint, case-to-nozzle joint, nozzle, factory joint, local propellant grain contour, ignition system and ground support equipment. Design criteria were established for each component to ensure a safe design with an adequate margin of safety.

Field Joint -- The field joint metal parts, internal case insulation and seals were redesigned and a weather protection system was added. In the STS 51-L design, the application of actuating pressure to the upstream face of the O-ring was essential for proper joint sealing performance because large sealing gaps were created by pressure-induced deflections, compounded by significantly reduced o-ring sealing performance at low temperature.

The major motor case change is the new tang capture feature which provides a positive metal-to-metal interference fit around the circumference of the tang and clevis ends of the mating segments. The interference fit limits the deflection between the tang and clevis o-ring sealing surfaces due to motor pressure and structural loads. The joints are designed so the seals will not leak under twice the expected structural deflection and rate. External heaters with integral weather seals were incorporated to maintain the joint and o-ring temperature at a minimum of 75 degrees F. The weather seal also prevents water intrusion into the joint.

The new design, with the tang capture feature, the interference fit and the use of custom shims between the outer surface of the tang and inner surface of the outer clevis leg, controls the O-ring sealing gap dimension. The sealing gap and the O-ring seals are designed so there is always a positive compression (squeeze) on the O-rings. The minimum and maximum squeeze requirements include the effects of temperature, O-ring resiliency and compression set and pressure. The clevis o-ring groove dimension has been increased so the o-ring never fills more than 90 percent of the o-ring groove, enhancing pressure actuation.

The new field joint design also includes a new O-ring in the capture feature and an additional leak check port to assure that the primary O-ring is positioned in the proper sealing direction at ignition. This new or third O-ring also serves as a thermal barrier should the sealed insulation be breached. Although not demanded by the specification, it has proved to be an excellent hot gas seal. The field joint internal case insulation was modified to be sealed with a pressure actuated flap called a J-seal, rather than with putty as in the STS 51-L configuration. Longer field joint case mating pins, with a reconfigured retainer band, were added to improve the shear strength of the pins and increase the margin of safety in the metal parts of the joint.

Case-to-Nozzle Joint -- The SRM case-to-nozzle joint, which experienced several instances of O-ring erosion in flight, has been redesigned to the same criteria imposed upon the case field joint. Similar to the field joint, case-to-nozzle joint modifications have been made in the metal parts, internal insulation and O-rings. Radial bolts with "Stat-O-Seals" were added to minimize the joint sealing gap opening. The internal insulation was modified to be sealed adhesively and a third O-ring included. The third O-ring serves as a dam or wiper in front of the primary O-ring to prevent the polysulfide adhesive from being extruded into the primary O-ring groove. It also serves as a thermal barrier should the polysulfide adhesive be breached. Like the third O-ring in the field joint, it has proven to be an effective hot gas seal. The polysulfide adhesive replaces the putty used in the 51-L joint. Also, an additional leak check port was added to reduce the amount of trapped air in the joint during the nozzle installation process and aid in the leak check procedure.

Nozzle -- The internal joints of the nozzle metal parts have been redesigned to incorporate redundant and verifiable O-rings at each joint. The nozzle steel fixed housing part has been redesigned to permit incorporation of 100 radial bolts that attach the fixed housing to the case aft dome. Improved bonding techniques are used for the nozzle nose inlet, cowl/boot and aft exit cone assemblies. The nose inlet assembly metal part to ablative parts bondline distortion has been eliminated by increasing the thickness of the aluminum nose inlet housing and improving the bonding process. The tape wrap angle of the carbon cloth fabric in the areas of the nose inlet and throat assembly parts were changed to improve the ablative insulation erosion tolerance. Some of these ply angle changes were in progress prior to the STS 51-L accident. The cowl and outer boot ring has additional structural support with increased thickness and contour changes to increase their margins of safety. Additionally, the outer boot ring ply configuration was altered.

Factory Joint -- Minor modifications were made in the case factory joints by increasing the insulation thickness and altering the lay-up to increase the margin of safety on the internal insulation. Longer pins also were added, along with a reconfigured retainer band and new weather seal to improve the factory joint performance and increase the margin of safety. The O-ring and O-ring groove size also were changed consistent with the field joint.

Propellant -- The motor propellant forward transition region was recontoured to reduce the stress fields between the star and cylindrical portions of the propellant grain.

Ignition System -- Several minor modifications were incorporated into the ignition system. The aft end of the igniter steel case, which contains the igniter nozzle insert, was thickened to eliminate a localized weakness. The igniter internal case insulation was tapered to improve the manufacturing process.

Ground Support Equipment -- The Ground Support Equipment (GSE) has been redesigned to minimize the case distortion during handling at the launch site; to improve the segment tang and clevis joint measurement system for more accurate reading of case diameters to facilitate stacking; to minimize the risk of O-ring damage during joint mating; and to improve leak testing of the igniter, case and nozzle field joints. Other GSE modifications include transportation monitoring equipment and lifting beam.

Test Program
An extensive test program was conducted to certify the redesigned motor for flight. Test activities included laboratory and component tests, subscale tests, simulator tests and full scale tests. Laboratory and component tests were used to determine component properties and characteristics. Subscale tests were used to simulate gas dynamics and thermal conditions for components and subsystem design. Simulator tests, consisting of motors using full size flight type segments, were used to verify joint design under full flight loads, pressure and temperature. Full scale tests were used to verify analytical models; determine hardware assembly characteristics; determine joint deflection characteristics; determine joint performance under full duration, hot gas tests including joint flaws and flight loads; and determine redesigned hardware structural characteristics.

Five full scale, full duration motor static firing tests were conducted prior to STS-26 to verify the redesigned solid rocket motor performance. These included two development motor tests, two qualification motor (QM) tests, and a production verification motor test. Additionally, one post-STS-26 QM test is scheduled in late December to certify the redesigned motor for cold weather operation. (Source: STS-26 Press Kit)

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Re: Discovery STS-26 – The Dream is Alive
« Reply #9 on: 06/20/2012 09:33 AM »
SPACE SHUTTLE MAIN ENGINE IMPROVEMENTS

The main engines for Space Shuttle flight STS-26 incorporate numerous improvements over those on previous flights. Through an extensive, ongoing engine test program, NASA has identified, developed, certified and implemented dozens of modifications to the Space Shuttle main engine. In terms of hardware, areas of improvement include the electronic engine controller, valve actuators, temperature sensors, main combustion chamber and the turbopumps. In the high pressure turbomachinery, improvements have focused on the turbine blades and bearings to increase margin and durability. The main combustion chamber has been strengthened by nickel-plating a welded outlet manifold to give it extended life.

Margin improvements also have been made to the five hydraulic actuators to preclude a loss in redundancy -- a situation which occurred twice on the launch pad. To address several instances of flight anomalies involving a temperature sensor in the critical engine cutoff logic, the sensor has been redesigned and extensively tested without problems.

Along with hardware improvements, several major reviews were conducted on requirements and procedures. These reviews dealt with topics such as possible failure modes and effects, and the associated critical items list. Another review involved having a launch/abort reassessment team examine all launch-commit criteria, engine redlines and software logic. A design certification review also was performed. In combination, these reviews have maximized confidence for successful engine operation.

A related effort saw Marshall engineers, working with their counterparts at the Kennedy Space Center, accomplish a comprehensive launch operations and maintenance review. This ensured that engine processing activities at the launch site are consistent with the latest operational requirements. In parallel with the various reviews, the most aggressive ground testing program in the history of the main engine was conducted. Its primary purposes were to certify the improvements and demonstrate the engine's reliability and operating margin. It was carried out at NASA's Stennis Space Center (formerly National Space Technology Laboratories) in Mississippi and at Rocketdyne's Santa Susana Field Laboratory in California. The other vital area of ground testing activity was checkout and acceptance of the three main engines for the STS-26 mission. Those tests, also at Stennis, began in August 1987 and all three STS-26 engines were delivered to Kennedy by January 1988. (Source: STS-26 Press Kit)

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Re: Discovery STS-26 – The Dream is Alive
« Reply #10 on: 06/20/2012 09:36 AM »

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Re: Discovery STS-26 – The Dream is Alive
« Reply #11 on: 06/20/2012 09:37 AM »
TDRS tries again aboard Discovery

(published in Countdown, STS-26 Preview Issue, October 1988)

TDRS is a jinx. A look at its history aboard the shuttle will tell you that. STS-26, with a Tracking and Data Relay Satellite as the primary payload, will be trying to break The Jinx. Sitting on Pad 39B inside Discovery’s payload bay, TDRS-C marks the second step toward a global communications network that will make many of the numerous ground stations throughout the world obsolete.

The TDRS system, born April 4, 1983, with the launch of TDRS-A, is designed to provide continuous global coverage of earth-orbiting spacecraft above 1,200 km (750 miles) up to an altitude of 5,000 km (3,100 miles). The system is capable of almost full-time coverage for the shuttle and up to 25 other orbiting spacecraft simultaneously and is designed for use with more than 40 types of spacecraft. Prior to the STS-26 flight, TDRS-A has routinely supplied coverage for nine satellites. A single TDRS can cover a user satellite for 50 percent of the craft’s orbital period.

The current mode of support for orbiting vehicles not utilizing the TDRS system only allows communication for about 15 percent of the craft’s orbital period using complex relaying of signals from one ground station to another. With TDRS the flow of information increases while the cost of utilizing satellite tracking relay stations decreases.

The TDRS system’s communications capability includes voice, television, analog and digital communication. In order to increase system reliability and availability there is no processing of signals done onboard the satellites. The data acquired by the TDRS system (each satellite is capable of handling up to 300 million bits of information per second) is relayed to a single ground terminal at White Sands Test Facility, New Mexico. From there the information is sent directly to NASA control centers at Johnson Space Center, Houston, for shuttle operations and to the Goddard Flight Center, Greenbelt, Maryland, which schedules TDRS system operations.

The TDRS system is fully owned by Continental Telecommunication, Inc. (CONTEL). When they bought out Fairchild Industries’ share of the TDRS, a partnership known as Space Communications Co. (SPACECOM) ceased to exist. The TDRS satellites, built by TRW, are the largest privately owned telecommunications spacecraft ever built. Each of CONTEL’s satellites weighs about 5,000 lbs. and spans more than 57 ft. across its solar panels. The single-access antennas, fabricated of molybdenum and plated with 14K gold, each measure 16 ft. in diameter and 42 ft. from tip to tip. The satellite consists of two modules, the equipment module and the telecommunications payload module. The equipment module houses the subsystems that operate the satellite. The telecommunications payload module contains electronic equipment for linking the user spacecraft with the ground terminals.

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Re: Discovery STS-26 – The Dream is Alive
« Reply #12 on: 06/20/2012 09:39 AM »
The seven-antennaed TDRS, although peculiar, hardly looks like a space mariner’s albatross, but the TDRS history is pock-marked with one problem after another. TDRS-A could be considered a microcosm of the system itself and the problems the system has experienced. Mission STS-6, during which TDRS-A was deployed, was originally scheduled for launch in early 1983, but suffered a number of critical delays prior to launch. The most significant delay involved the satellite itself. A February rain storm, with winds gusting to 65 mph, caused dust contamination of TDRS-A, which postponed the launch until April 4.

After a successfully deployment from Challenger’s payload bay, The Jinx struck. A failure occurred while the 32,500-lbs Inertial Upper Stage was attempting to boost the satellite into its geosynchronous orbit, causing the satellite and booster to begin tumbling out of control at a rate of 30 revolutions per minute. Only quick action by NASA, TRW and SPACECOM engineers saved TDRS-A. The engineers were able to gain control of the IUS and the satellite, but TDRS was apparently stranded far from its intended orbit and was damaged in the process. Using tiny one-pound thrusters, the 5,000-lbs craft was maneuvered 8,662 miles farther into space to achieve its planned geosynchronous orbit of 22,237 miles on June 19, 1983. TDRS-A (called TDRS-1 after launch) reached its permanent orbit October 17 after almost six months of planning and maneuvering. TDRS-1 is now on station above the equator near the city of Fortalenza on the north coast of Brazil.

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Re: Discovery STS-26 – The Dream is Alive
« Reply #13 on: 06/20/2012 09:40 AM »
The Jinx did not end for TDRS-1 with its placement on station. On December 12, 1983, NASA announced that the satellite’s transmitting capability on an S-band single access antenna (SA-1) failed. S-band communications provide voice and data links between low-earth orbiting satellites, including the shuttle, and ground based stations. During a press conference May 19, 1988, Charles M. “Chuck” Hunter, TDRS deputy project manager at Goddard Space Flight Center, cleared up a common misconception that the S-band communication capability is lost. According to Hunter, the S-band antennas are now fully operational. In 1983, NASA also reported that SA-2 was functioning properly and SA-1 was still able to receive transmissions, so NASA claimed little or no loss of service to customers.

Still the system’s problems, and The Jinx, continued. A high-rate forward KU-band link that was to be used during the flight of STS-9/Spacelab 1 was shut down November 21, 1983, after three Traveling Wave Tube Amplifiers (TWTAs) and a diplexer failed three days earlier. The forward link is now restricted to emergency use only. Despite the problems with the forward link, officials said they were confident that the problem would not hinder the flow of high speed data from Spacelab to the ground. Apparently the officials were right. A report by TRW says TDRS-1 provided “over 99percent availability in communications support.” The report continued: “NASA was able to initiate communications with STS-9 in late 1983 via the TDRS system just nine minutes after lift-off. On each of the approximately 90-minute orbits, The STS-9/Spacelab 1 crew had about 50 continuous minutes available via TDRS-1 to communicate and relay data to scientists and technicians on Earth below. This compares to approximately 13 minutes of total orbit coverage previously available using the older NASA ground tracking stations.”

Despite the satellite’s eventual success, the IUS failure delayed the launch of TDRS-B, which had been set for an August 1983 deployment, while the problem was examined and a solution developed. The IUS flaws, in a nozzle support ring, were found, corrected and the TDRS hex was apparently broken, but along came TDRS-B.

TDRS-B was to fly into space as part of the 16th mission, 51-E, right behind Congressman Jake Garn on March 1, 1985, aboard Challenger. The Jinx began nibbling at the mission as Challenger sat on launch pad 39A. Damaged insulation tiles and leaks in the External Tank’s fuel lines delayed the launch until March 7. Then The Jinx struck full force. TDRS-B was removed from the payload bay March 1 because of a design flaw in the satellite that would not allow it to communicate with its sister TDRS-1. The entire mission had to be cancelled just days prior to launch. Later, it was revealed that repairs to TDRS-B would delay the satellite’s launch date more than 10 months. The second satellite found its way into the bay of Challenger for the January 28, 1986, launch…

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Re: Discovery STS-26 – The Dream is Alive
« Reply #14 on: 06/20/2012 09:42 AM »
…Today, Discovery sits on launch pad 39B with TDRS-C in her payload bay awaiting lift-off of the 26th shuttle mission. TDRC-C was fueled August 23 after a leak in the Reaction Control System was finally repaired. Despite more than two and a half years of preparation and redesigning, one delay after another causes the launch date to slip. Has The Jinx once again reared its ugly head?

NASA does not believe in jinxes. Instead of superstition, they look to hard engineering facts to help them make their decisions – Discovery should be the best-prepared shuttle yet to fly, the perfect vehicle to erase the black marks of the past.

Fact: The addition of TDRS-C to the system will increase communication contact from 50 percent to around 90 percent. Fact: A complete TDRS system is needed to support the large stream of science data from waiting science missions such as the Hubble Space Telescope. Fact: With two TDRS in place, NASA’s advanced plans for space science and exploration can move forward.

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Re: Discovery STS-26 – The Dream is Alive
« Reply #15 on: 06/20/2012 09:43 AM »
The future starts here: TDRS-C will be deployed 6 hours and 12 minutes MET into Discovery’s flight on orbit five, as the shuttle passes over the Pacific Ocean within coverage of Hawaii and Guam ground stations. As in the past, the crew will move to a safe distance away from the TDRS/IUS combination and allow the IUS perigee kick motor to fire. At 6:28 MET Discovery will be maneuvered into IUS viewing attitude and 26 minutes later the crew will position the orbiter in its “window protect” attitude, during which time the shuttle’s viewing windows are turned away from the TDRS/IUS burn plume.

After the IUS first-stage burn, that stage will be jettisoned and the TDRS/IUS second stage stock will coast on its way to geosynchronous orbit. Once there, the IUS second stage will fire to stabilize the satellite in its orbit. The IUS will then be jettisoned and maneuvered away from the TDRS. Once positioned, TDRS-2 (West) will initially reside at 150 degrees west, where it will support the STS-27 mission, before being moved over the Pacific Ocean southwest of Hawaii at 171 degrees west longitude.

TDRS-1 (East), currently stationed over the Atlantic Ocean at 41 degrees west longitude, will remain in place until the third TDRS is placed on orbit, at which time the two will exchange positions, with TDRS-1 becoming the on-orbit spare. The controlling ground station terminal at White Sands, New Mexico, will configure the TDRS system for on-orbit operations.

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Re: Discovery STS-26 – The Dream is Alive
« Reply #16 on: 06/20/2012 09:44 AM »

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Re: Discovery STS-26 – The Dream is Alive
« Reply #17 on: 06/20/2012 09:45 AM »

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Re: Discovery STS-26 – The Dream is Alive
« Reply #18 on: 06/20/2012 09:48 AM »

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Re: Discovery STS-26 – The Dream is Alive
« Reply #19 on: 06/20/2012 09:51 AM »

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