Key Concepts
- Satellite retrieval mission: An unprecedented attempt to recover two stranded satellites (PALAPA B2 and WESTAR 6) from low-Earth orbit.
- MMU (Manned Maneuvering Unit): A space jetpack used by astronauts for independent movement in space.
- Stinger: A device resembling a folded umbrella, designed to be inserted into the satellite's rocket motor to capture it.
- Robotic arm: A 50-foot (15-meter) long mechanical arm on the space shuttle used for manipulating objects in space.
- EVA (Extravehicular Activity): Spacewalk.
- Plan B: Contingency plans developed by the crew to address potential failures during the mission.
- Tiger Team: A group of specialists called in to solve unexpected problems during a mission.
- For Sale Sign: A sign held by astronaut Dale Gardner in space after the successful retrieval of the two satellites.
The Stranded Satellites
In February 1984, two satellites, PALAPA B2 (Indonesian) and WESTAR 6 (Western Union), worth a combined $150 million, were stranded in incorrect orbits following their launch from the Space Shuttle Challenger. The satellites were fully functional, but their misplacement led to insurance payouts of $180 million. Insurance underwriters were keen to recover the satellites for resale.
The Audacious Rescue Mission
NASA decided to undertake a mission to retrieve the stranded satellites, a feat never before attempted. The mission was assigned to the Space Shuttle Discovery (STS-51-A), with a crew of five astronauts, including Commander Rick Hauck, pilot David Walker, mission specialists Joe Allen and Dale Gardner, and astronaut Anna Fisher.
Pre-Launch Concerns and Preparations
Commander Rick Hauck expressed concern over a NASA official's statement that retrieving the satellites would be easy, emphasizing the mission's inherent risks. The crew developed contingency plans (Plan B's) for potential failures.
Grabbing the Satellites
The initial plan involved using the MMU to approach the spinning satellites and capture them using a device called the "Stinger." The Stinger, manually operated, would be inserted into the satellite's rocket motor, and its umbrella-like tines would secure the satellite. The robotic arm would then maneuver the satellite into the shuttle's payload bay.
Simulation and Training
Flight controller Ron Zaguli and mission specialist Anna Fisher spent extensive time in the simulator, perfecting the maneuvers required for capturing and securing the satellites.
The Mission: Day 5 - PALAPA B2 Retrieval
On the fifth day of the mission, Discovery approached PALAPA B2. Joe Allen, using the MMU and the Stinger, successfully inserted the device into the satellite's rocket motor.
The A-Frame Problem and Improvisation
The A-frame, a tool designed to attach to the top of the satellite to allow the robotic arm to grab it, did not fit due to a small ridge on the satellite. This forced the crew to abandon the original plan and improvise.
Plan B: Manual Grapple
The crew decided that Allen would manually hold the top of the satellite while Gardner attached a clamp to the bottom, securing it in the payload bay. This was a risky maneuver, as Allen would be holding a large, heavy object in space with limited tactile sense due to his spacesuit.
The Manual Retrieval
Anna Fisher used the robotic arm to position the satellite in front of Allen, who grabbed the antenna. Allen held the satellite while Gardner worked to attach the clamp. After 45 minutes, Gardner successfully attached the clamp, and the satellite was secured in the payload bay.
WESTAR 6 Retrieval
The crew decided to use the same manual retrieval technique for WESTAR 6. Dale Gardner, using the MMU, captured the satellite, and it was secured in the payload bay.
"Satellite for Sale"
After successfully retrieving both satellites, Dale Gardner held up a "for sale" sign in space, a joke referencing the insurance companies' intention to sell the satellites.
Presidential Recognition
President Ronald Reagan called the astronauts to congratulate them on their accomplishment, highlighting the importance of the mission to the space shuttle program.
Significance of the Mission
The mission demonstrated the flexibility and capabilities of the space shuttle, proving its ability to work in space in ways previously unimaginable. It also sparked renewed interest in the space shuttle program.
Next Episode Teaser
The next episode will focus on Christa McAuliffe, the teacher selected to be the first citizen passenger in space.
Synthesis/Conclusion
The STS-51-A mission was a remarkable achievement, showcasing the ingenuity, adaptability, and teamwork of the NASA astronauts and mission control team. Despite facing unexpected challenges, the crew successfully retrieved two stranded satellites, demonstrating the potential of the space shuttle program and inspiring a new generation of space enthusiasts. The mission's success was a testament to the meticulous planning, rigorous training, and the ability to improvise in the face of adversity.
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