Space Shuttle Endeavour liftoff for Hubble Repair Mission, STS-61. Credits: NASA

A Space Mission to the rescue of the Hubble Telescope: STS-61

The STS-61 Mission was one of the most intrepid and complex operations in the history of space, let's find out in detail how it saved the Hubble Space Telescope

In December 1993, the Space Shuttle Endeavour participated in a historic mission known as STS-61, aimed at repairing and restoring the Hubble Space Telescope (HST). This mission would have proven to be critical in the history of space exploration, as it not only revitalized the Hubble Space Telescope, but experienced such a major repair mission in orbit for the first time. 

STS-61 mission patch. Credits: SpaceFacts
STS-61 mission patch. Credits: SpaceFacts

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The Hubble’s joy and pain

On April 24, 1990, the STS-31 mission saw the launch of Discovery with the Hubble Space Telescope on board, and it soon became apparent that there were significant issues with its primary mirror.

Space Shuttle Endeavour liftoff for Hubble Repair Mission, STS-61. Credits: NASA
Space Shuttle Endeavour liftoff for Hubble Repair Mission, STS-61. Credits: NASA

A flaw in the mirror’s curvature caused images to be distorted and blurry, blocking the telescope’s ability to capture the breathtaking views of the cosmos. The Hubble’s compromised vision disappointed scientists and the public, prompting the need for a risky rescue mission.


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Rescue mission on the way

The only way to make the telescope fully operational was to intervene on-site, thus the idea of a rescue mission rather than a repair one was born. The mission required intricate spacewalks, complex repairs, and the installation of new instruments to enhance the telescope’s capabilities.

The astronauts selected for the mission went through extensive training to ensure they could successfully carry out these extremely complex tasks.

Astronauts training before STS-61. Credits: NASA
Astronauts training before STS-61. Credits: NASA

The beginning of the adventure

On December 2, 1993, the Space Shuttle Endeavour lifted off from the Kennedy Space Center, carrying a crew of seven astronauts on a mission to rescue the Telescope.

Hubble’s first service mission took on great importance given the severity of the damage to the mirror. The crew skilfully executed a series of repairs and upgrades using more than one hundred tools. The most critical task involved installing the Corrective Optics Space Telescope Axial Replacement (COSTAR), a device designed to compensate for Hubble’s faulty optics. This ingenious solution effectively turned the HST into the powerful observatory it was designed.

Training pool for simulate microgravity environment. Credits: NASA/JSC Digital Image Collection
Training pool for simulate microgravity environment. Credits: NASA/JSC Digital Image Collection

Astronauts in action

During all the five spacewalks, the astronauts faced numerous challenges as they worked to revive the Hubble.

They replaced the telescope’s main camera, installed new solar arrays, and conducted intricate repairs on its gyros and data recorders. The onboard computers were upgraded with additional coprocessors, and the Hubble’s orbit was raised. These tasks required exceptional precision and coordination, as the astronauts operated in the microgravity environment of space.

Work in progress on HST. Credits: NASA
Work in progress on Hubble Space Telescope. Credits: NASA

Following the successful completion of STS-61, the Hubble Space Telescope underwent a remarkable transformation. On January 13, 1994, NASA declared that the mission had been a complete success.

The corrective measures implemented during the mission resolved the optical issues, enabling the telescope to capture awe-inspiring images with unprecedented clarity. The restored Hubble symbolized scientific triumph and human ingenuity, captivating the world with its stunning visuals and groundbreaking discoveries.

The Hubble Space Telescope, Credit: NASA
The Hubble Space Telescope, Credit: NASA

A full maintenance program

Hubble was designed to experience regular upgrades over time.

STS-61 showcased the ingenuity and creativity of NASA and its astronauts. The mission’s success demonstrated the importance of human spaceflight in servicing and maintaining crucial scientific instruments in space. Since then, subsequent Space Shuttles and robotic servicing missions have extended Hubble’s lifespan and capabilities until the last repairing mission held by Atlantis in May 2009 during the STS-125 mission, which also installed 2 new observation instruments.

Hubble docked with Space shuttle Endeavour. Credits: NASA
Hubble docked with Space shuttle Endeavour. Credits: NASA

NASA flew 5 service missions over the years, numbered SM 1, 2, 3A, 3B, and 4. All of these used the Space Shuttles, the first in December 1993 and the last, as previously said, in May 2009. All the missions began with intercept maneuvers of the telescope in orbit and then grappled it with the help of the Shuttle’s robotic arm.

After the repairing phase, the telescope was released into a slightly higher orbit to compensate for orbital decay caused by atmospheric friction.

A testimony for the future

The IMAX project is a collaboration between NASA and the Smithsonian Institution’s National Air and Space Museum to document significant space activities using the IMAX film medium.

An IMAX camera system was flown on Shuttle Mission STS-61 and was used by Endeavour’s crew to collect material for upcoming IMAX productions. IMAX Cargo Bay Camera (ICBC) was carried in the payload bay of Endeavour: the camera was mounted in a pressure-sealed container with a viewing window.

The window had a sliding door that opened when the camera was operating. The camera was controlled from the aft-flight deck, exposing the film through a 30mm fisheye lens.

Hoffman on board the Endeavour with the IMAX camera. Credits: SpaceFacts
Hoffman on board the Endeavour with the IMAX camera. Credits: SpaceFacts
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Federico Coppola

Federico Coppola

Graduated in history from Federico II University in Naples, passionate about space, writing, and with an incurable dream of flying up through the clouds to reach the stars.
Admin of the Instagram page Italian_space_meme

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