Extremely Remote Repairs

Background: Do you get frustrated when your printer doesn’t work? Imagine if your printer was built in 1970 and billions of miles away from you.

Recently, NASA faced a significant challenge with the Voyager 1 spacecraft, one of humanity's farthest and oldest space probes, which is currently over 14 billion miles away from Earth. In November, the spacecraft began sending back data that was completely unintelligible.

NASA engineers devised a novel approach to address this issue. They sent a command to "poke" the Flight Data Subsytem (FDS) to return a readout of its memory. This diagnostic step allowed them to pinpoint the exact location of the memory fault. The readout showed that a single memory chip within the FDS had likely failed, either due to a cosmic ray hit or simply the age-related degradation of the hardware.

During the repairs, commands had to travel over 21 hours each way at the speed of light, meaning any adjustments would take nearly two days to implement and confirm. After sending the corrective commands, NASA's team had to wait anxiously for the results.

Finally, a breakthrough came when the reprogrammed instructions were successfully received and executed by Voyager 1, restoring the spacecraft's ability to send back comprehensible data. This repair not only solved the immediate problem but also helped to extend the lifespan of this venerable spacecraft, allowing it to continue its mission of exploring the interstellar medium.

NASA sends something to space and then has to fix it? We’ve been there before.

Deja Vu:

NASA was able to “work from home” while they fixed Voyager, but another big fix required them to “work on-site”.

Two months after its launch, on June 27, 1990, NASA announced that the Hubble telescope was flawed. Both of Hubble’s imaging cameras (the Wide Field and Planetary Camera and the Faint Object Camera) showed the same characteristic distortion, called spherical aberration.

The solution? Install a set of "contact lenses" in space. This not only fixed the vision but also turned Hubble into the legendary observatory we know today.

Officially known as STS-61. This mission, carried out by Space Shuttle Endeavour, took place from December 2 to December 13, 1993. The crew installed a new instrument, the Corrective Optics Space Telescope Axial Replacement (COSTAR), which acted much like eyeglasses by compensating for the flawed shape of the mirror.

Prior to STS-61, there was no precedent for such a complex repair job in space. The mission's success not only saved Hubble from being a costly failure but also solidified the concept of maintaining and upgrading satellites and telescopes post-launch.

Fact:

During the repair mission, Hubble was also equipped with a new camera that captured images with ten times the clarity of its original hardware. Hey, if you’re going up to space to fix something, you might as well bring an upgrade or two.

Definition: Spherical Aberration

Two months after its launch, NASA announced that the Hubble telescope was flawed, and the diagnosis was a bad case of spherical aberration. It’s a type of optical flaw that occurs when light rays that pass through the edge of a lens or mirror focus at a slightly different point than those that pass through the center. This results in a blurred or distorted image, as not all the light converges to the same focal point.

NASA Numbers:

2.2 Microns: The edge of the 2.4-meter mirror on the Hubble Telescope was too flat by about 2.2 microns (a fraction of the width of a human hair). This tiny deviation was enough to cause significant blurring of images, and lead to STS-61.

35 hours, 28 minutes: It took five back-to-back space walks totaling 35 hours and 28 minutes to complete STS-61

Profile: Dr. Kathryn Sullivan: mission specialists on STS-61.

Kathryn Sullivan is a distinguished American geologist and a former NASA astronaut, known for her significant contributions to both oceanography and space science.

Born on October 3, 1951, in Paterson, New Jersey, Sullivan was one of the first six women to join NASA's astronaut corps in 1978 and has had a storied career in both terrestrial and space exploration.

Space Shuttle Missions: Kathryn Sullivan flew on three space shuttle missions. Her first was STS-41-G in 1984, during which she became the first American woman to perform a spacewalk.

Oceanography and Government Roles: After leaving NASA, Sullivan served as the chief scientist of the National Oceanic and Atmospheric Administration (NOAA), where she worked on projects related to weather and climate science. She later became the Under Secretary of Commerce for Oceans and Atmosphere and NOAA Administrator in 2014.

Recommended Reading: The Hubble Wars: Astrophysics Meets Astropolitics in the Two-Billion-Dollar Struggle over the Hubble Space Telescope by Eric J. Chaisson

Eric Chaisson, a former senior scientist on the HST project, tells the inside story of the much heralded mission to fix the telescope. Drawing on his journals, Chaisson recreates the day-to-day struggles of scientists, politicians, and publicists to fix the telescope and control the political spin. Illustrated with “before and after” full-color pictures from the telescope and updated with a new preface, The Hubble Wars tells an engaging tale of scientific comedy and error.