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25 Years Ago: STS-103, The Hubble Servicing Mission-3A
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Explore Hubble Hubble Home Overview About Hubble The History of Hubble Hubble Timeline Why Have a Telescope in Space? Hubble by the Numbers At the Museum FAQs Impact & Benefits Hubble’s Impact & Benefits Science Impacts Cultural Impact Technology Benefits Impact on Human Spaceflight Astro Community Impacts Science Hubble Science Science Themes Science Highlights Science Behind Discoveries Hubble’s Partners in Science Universe Uncovered Explore the Night Sky Observatory Hubble Observatory Hubble Design Mission Operations Missions to Hubble Hubble vs Webb Team Hubble Team Career Aspirations Hubble Astronauts News Hubble News Hubble News Archive Social Media Media Resources Multimedia Multimedia Images Videos Sonifications Podcasts e-Books Online Activities Lithographs Fact Sheets Posters Hubble on the NASA App Glossary More 35th Anniversary Online Activities Hubble captured this image of supernova SN 2022abvt (the pinkish-white dot at image center) about two months after it was discovered in 2022. ESA/Hubble & NASA, R. J. Foley (UC Santa Cruz)
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A supernova and its host galaxy are the subject of this NASA/ESA Hubble Space Telescope image. The galaxy in question is LEDA 132905 in the constellation Sculptor. Even at more than 400 million light-years away, LEDA 132905’s spiral structure is faintly visible, as are patches of bright blue stars.
The bright pinkish-white dot in the center of the image, between the bright center of the galaxy and its faint left edge, is a supernova named SN 2022abvt. Discovered in late 2022, Hubble observed SN 2022abvt about two months later. This image uses data from a study of Type Ia supernovae, which occur when the exposed core of a dead star ignites in a sudden, destructive burst of nuclear fusion. Researchers are interested in this type of supernova because they can use them to measure precise distances to other galaxies.
The universe is a big place, and supernova explosions are fleeting. How is it possible to be in the right place at the right time to catch a supernova when it happens? Today, robotic telescopes that continuously scan the night sky discover most supernovae. The Asteroid Terrestrial-impact Last Alert System, or ATLAS, spotted SN 2022abvt. As the name suggests, ATLAS tracks down the faint, fast-moving signals from asteroids close to Earth. In addition to searching out asteroids, ATLAS also keeps tabs on objects that brighten or fade suddenly, like supernovae, variable stars, and galactic centers powered by hungry black holes.
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The Death Throes of Stars
Homing in on Cosmic Explosions
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Claire Andreoli (claire.andreoli@nasa.gov)
NASA’s Goddard Space Flight Center, Greenbelt, MD
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Last Updated Feb 07, 2025 Editor Andrea Gianopoulos Location NASA Goddard Space Flight Center Related Terms
Hubble Space Telescope Galaxies Goddard Space Flight Center Spiral Galaxies Stars Supernovae The Universe Keep Exploring Discover More Topics From Hubble
Hubble Space Telescope
Since its 1990 launch, the Hubble Space Telescope has changed our fundamental understanding of the universe.
Hubble’s Night Sky Challenge
Reshaping Our Cosmic View: Hubble Science Highlights
Hubble’s 35th Anniversary
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Explore Hubble Hubble Home Overview About Hubble The History of Hubble Hubble Timeline Why Have a Telescope in Space? Hubble by the Numbers At the Museum FAQs Impact & Benefits Hubble’s Impact & Benefits Science Impacts Cultural Impact Technology Benefits Impact on Human Spaceflight Astro Community Impacts Science Hubble Science Science Themes Science Highlights Science Behind Discoveries Hubble’s Partners in Science Universe Uncovered Explore the Night Sky Observatory Hubble Observatory Hubble Design Mission Operations Missions to Hubble Hubble vs Webb Team Hubble Team Career Aspirations Hubble Astronauts News Hubble News Hubble News Archive Social Media Media Resources Multimedia Multimedia Images Videos Sonifications Podcasts e-Books Online Activities Lithographs Fact Sheets Posters Hubble on the NASA App Glossary More 35th Anniversary Online Activities 5 Min Read Straight Shot: Hubble Investigates Galaxy with Nine Rings
LEDA 1313424, aptly nicknamed the Bullseye, is two and a half times the size of our Milky Way and has nine rings — six more than any other known galaxy. Credits:
NASA, ESA, Imad Pasha (Yale), Pieter van Dokkum (Yale) NASA’s Hubble Space Telescope has captured a cosmic bullseye! The gargantuan galaxy LEDA 1313424 is rippling with nine star-filled rings after an “arrow” — a far smaller blue dwarf galaxy — shot through its heart. Astronomers using Hubble identified eight visible rings, more than previously detected by any telescope in any galaxy, and confirmed a ninth using data from the W. M. Keck Observatory in Hawaii. Previous observations of other galaxies show a maximum of two or three rings.
“This was a serendipitous discovery,” said Imad Pasha, the lead researcher and a doctoral student at Yale University in New Haven, Connecticut. “I was looking at a ground-based imaging survey and when I saw a galaxy with several clear rings, I was immediately drawn to it. I had to stop to investigate it.” The team later nicknamed the galaxy the “Bullseye.”
LEDA 1313424, aptly nicknamed the Bullseye, is two and a half times the size of our Milky Way and has nine rings — six more than any other known galaxy. High-resolution imagery from NASA’s Hubble Space Telescope confirmed eight rings, and data from the W. M. Keck Observatory in Hawaii confirmed a ninth. Hubble and Keck also confirmed which galaxy dove through the Bullseye, creating these rings: the blue dwarf galaxy that sits to its immediate center-left. NASA, ESA, Imad Pasha (Yale), Pieter van Dokkum (Yale)
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Hubble and Keck’s follow-up observations also helped the researchers prove which galaxy plunged through the center of the Bullseye — a blue dwarf galaxy to its center-left. This relatively tiny interloper traveled like a dart through the core of the Bullseye about 50 million years ago, leaving rings in its wake like ripples in a pond. A thin trail of gas now links the pair, though they are currently separated by 130,000 light-years.
“We’re catching the Bullseye at a very special moment in time,” said Pieter G. van Dokkum, a co-author of the new study and a professor at Yale. “There’s a very narrow window after the impact when a galaxy like this would have so many rings.”
Galaxies collide or barely miss one another quite frequently on cosmic timescales, but it is extremely rare for one galaxy to dive through the center of another. The blue dwarf galaxy’s straight trajectory through the Bullseye later caused material to move both inward and outward in waves, setting off new regions of star formation.
How big is the Bullseye? Our Milky Way galaxy is about 100,000 light-years in diameter, and the Bullseye is almost two-and-a-half times larger, at 250,000 light-years across.
This illustration compares the size of our own Milky Way galaxy to gargantuan galaxy LEDA 1313424, nicknamed the Bullseye. The Milky Way is about 100,000 light-years in diameter, and the Bullseye is almost two-and-a-half times larger, at 250,000 light-years across. NASA, ESA, Ralf Crawford (STScI)
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The researchers used Hubble’s crisp vision to carefully to pinpoint the location of most of its rings, since many are piled up at the center. “This would have been impossible without Hubble,” Pasha said.
They used Keck to confirm one more ring. The team suspects a 10th ring also existed, but has faded and is no longer detectable. They estimate it might lie three times farther out than the widest ring in Hubble’s image.
A One-to-One Match with Predictions
Pasha also found a stunning connection between the Bullseye and a long-established theory: The galaxy’s rings appear to have moved outward almost exactly as predicted by models.
“That theory was developed for the day that someone saw so many rings,” van Dokkum said. “It is immensely gratifying to confirm this long-standing prediction with the Bullseye galaxy.”
If viewed from above, it would be more obvious that the galaxy’s rings aren’t evenly spaced like those on a dart board. Hubble’s image shows the galaxy from a slight angle. “If we were to look down at the galaxy directly, the rings would look circular, with rings bunched up at the center and gradually becoming more spaced out the farther out they are,” Pasha explained.
To visualize how these rings may have formed, think about dropping a pebble into a pond. The first ring ripples out, becoming the widest over time, while others continue to form after it.
The researchers suspect that the first two rings in the Bullseye formed quickly and spread out in wider circles. The formation of additional rings may have been slightly staggered, since the blue dwarf galaxy’s flythrough affected the first rings more significantly.
This illustration shows the massive galaxy nicknamed the Bullseye face-on. Dotted circles indicate where each of its rings are, which formed like ripples in a pond after a blue dwarf galaxy (not shown) shot through its core about 50 million years ago. NASA’s Hubble Space Telescope helped researchers carefully pinpoint the location of most of its rings, many of which are piled up at the center. Data from the W. M. Keck Observatory in Hawaii helped the team confirm another ring. NASA, ESA, Ralf Crawford (STScI)
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Individual stars’ orbits were largely undisturbed, though groups of stars did “pile up” to form distinguishable rings over millions of years. The gas, however, was carried outward, and mixed with dust to form new stars, further brightening the Bullseye’s rings.
There’s a lot more research to be done to figure out which stars existed before and after the blue dwarf’s “fly through.” Astronomers will now also be able to improve models showing how the galaxy may continue to evolve over billions of years, including the disappearance of additional rings.
Although this discovery was a chance finding, astronomers can look forward to finding more galaxies like this one soon. “Once NASA’s Nancy Grace Roman Space Telescope begins science operations, interesting objects will pop out much more easily,” van Dokkum explained. “We will learn how rare these spectacular events really are.”
The team’s paper was published on the February 4, 2025 in The Astrophysical Journal Letters.
The Hubble Space Telescope has been operating for over three decades and continues to make ground-breaking discoveries that shape our fundamental understanding of the universe. Hubble is a project of international cooperation between NASA and ESA (European Space Agency). NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope and mission operations. Lockheed Martin Space, based in Denver, also supports mission operations at Goddard. The Space Telescope Science Institute in Baltimore, which is operated by the Association of Universities for Research in Astronomy, conducts Hubble science operations for NASA.
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Claire Blome and Ray Villard
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Last Updated Feb 04, 2025 Editor Andrea Gianopoulos Location NASA Goddard Space Flight Center Related Terms
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Hubble Space Telescope
Since its 1990 launch, the Hubble Space Telescope has changed our fundamental understanding of the universe.
Reshaping Our Cosmic View: Hubble Science Highlights
Hubble’s 35th Anniversary
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The first shuttle mission of 1995, STS-63 included several historic firsts. As part of Phase 1 of the International Space Station program, space shuttle Discovery’s 20th flight conducted the first shuttle rendezvous with the Mir space station, in preparation for future dockings. The six-person crew included Commander James Wetherbee, Pilot Eileen Collins – the first woman to pilot a space shuttle mission – Payload Commander Bernard Harris, and Mission Specialists Michael Foale, Janice Voss, and Vladimir Titov. The spacewalk conducted during the mission included the first African American and the first British born astronauts to walk in space. The crew conducted 20 science and technology experiments aboard the third flight of the Spacehab module. The astronauts deployed and retrieved the SPARTAN-204 satellite that during its two-day free flight carried out observations of galactic objects using an ultraviolet instrument.
The STS-63 crew patch. The STS-63 crew of Janice Voss, front row left, Eileen Collins, James Wetherbee, and Vladimir Titov; Bernard Harris, back row left, and Michael Foale. The Shuttle-Mir program patch. NASA announced the six-person STS-63 crew in September 1993 for a mission then expected to fly in May 1994. Wetherbee, selected by NASA in 1984, had already flown twice in space, as pilot on STS-32 and commander of STS-52. For Collins, selected in the class of 1990 as the first woman shuttle pilot, STS-63 marked her first spaceflight. Also selected in 1990, Harris had flown previously on STS-55 and Voss on STS-57. Foale, selected as an astronaut in 1987, had flown previously on STS-45 and STS-56. Titov, selected as a cosmonaut in 1976, had flown two previous spaceflights – a two-day aborted docking mission to Salyut-7 and the first year-long mission to Mir – and survived a launch pad abort. He served as backup to Sergei Krikalev on STS-60, who now served as Titov’s backup.
Space shuttle Discovery rolls out to Launch Pad 39B. The STS-63 crew during the Terminal Countdown Demonstration Test in the White Room of Launch Pad 39B. The STS-63 astronauts walk out of crew quarters for the van ride out to the launch pad. Space shuttle Discovery arrived back at NASA’s Kennedy Space Center in Florida on Sept. 27, 1994, after a ferry flight from California following its previous mission, STS-64. Workers towed it to the Orbiter Processing Facility the next day. Following installation of the Spacehab, SPARTAN, and other payloads, on Jan. 5, 1995, workers rolled Discovery from the processing facility to the Vehicle Assembly Building for mating with an external tank and twin solid rocket boosters. Rollout to Launch Pad 39B took place on Jan. 10. On Jan. 17-18, teams conducted the Terminal Countdown Demonstration Test, a dress rehearsal for the countdown to launch planned for Feb. 2, with the astronaut crew participating in the final few hours as they would on launch day. They returned to Kennedy on Jan. 29 for final pre-launch preparations. On Feb. 2, launch teams called a 24-hour scrub to allow time to replace a failed inertial measurement unit aboard Discovery.
Launch of space shuttle Discovery on mission STS-63. STS-63 Commander James Wetherbee on Discovery’s flight deck. STS-63 Pilot Eileen Collins on Discovery’s flight deck. On Feb. 3, Discovery and its six-person crew lifted off from Launch Pad 39B at 12:22 a.m. EST, the time dictated by orbital mechanics – Discovery had to launch into the plane of Mir’s orbit. Within 8.5 minutes, Discovery had reached orbit, for the first time in shuttle history at an inclination of 51.6 degrees, again to match Mir’s trajectory. Early in the mission, one of Discovery’s 44 attitude control thrusters failed and two others developed minor but persistent leaks, threatening the Mir rendezvous.
View of the Spacehab module in Discovery’s payload bay. The SPARTAN-204 satellite attached to the remote manipulator system or robotic arm during the flight day two operations. On the mission’s first day in space, Harris and Titov activated the Spacehab module and several of its experiments. Wetherbee and Collins performed the first of five maneuvers to bring Discovery within 46 miles of Mir for the final rendezvous on flight day four. Teams on the ground worked with the astronauts to resolve the troublesome thruster problems to ensure a safe approach to the planned 33 feet. On flight day 2, as those activities continued, Titov grappled the SPARTAN satellite with the shuttle’s robotic arm and lifted it out of the payload bay. Scientists used the ultraviolet instrument aboard SPARTAN to investigate the ultraviolet glow around the orbiter and the aftereffects of thruster firings. The tests complete, Titov placed SPARTAN back in the payload bay.
The Mir space station as seen from Discovery during the rendezvous. Space shuttle Discovery as seen from Mir during the rendezvous. Mir during Discovery’s flyaround. On flight day three, the astronauts continued working on science experiments while Wetherbee and Collins completed several more burns for the rendezvous on flight day four, the thruster issues resolved to allow the close approach to 33 feet. Flying Discovery manually from the aft flight deck, and assisted by his crew mates, Wetherbee slowly brought the shuttle to within 33 feet of the Kristall module of the space station. The STS-63 crew communicated with the Mir-17 crew of Aleksandr Viktorenko, Elena Kondakova, and Valeri Polyakov via VHF radio, and the crews could see each other through their respective spacecraft windows. After station-keeping for about 10 minutes, Wetherbee slowly backed Discovery away from Mir to a distance of 450 feet. He flew a complete circle around Mir before conducting a final separation maneuver.
The SPARTAN-204 satellite as it begins its free flight on flight day five. STS-63 crew member Vladimir Titov works on an experiment in the Spacehab module. On the mission’s fifth day, Titov once again grappled SPARTAN with the robotic arm, but this time after raising it above the payload bay, he released the satellite to begin its two-day free flight. Wetherbee steered Discovery away from the departing satellite. During its free flight, the far ultraviolet imaging spectrograph aboard SPARTAN recorded about 40 hours of observations of galactic dust clouds. During this time, the astronauts aboard the shuttle continued work on the 20 experiments in Spacehab and prepared for the upcoming spacewalk.
STS-63 crew member Janice Voss operates the remote manipulator system during the retrieval of the SPARTAN-204 satellite. STS-63 astronauts Bernard Harris, left, and Michael Foale at the start of their spacewalk. Wetherbee and the crew flew the second rendezvous of the mission on flight day seven to retrieve SPARTAN. Voss operated the robotic arm to capture and stow the satellite in the payload bay following its 43-hour free flight. Meanwhile, Foale and Harris suited up in the shuttle’s airlock and spent four hours breathing pure oxygen to rid their bodies of nitrogen to prevent decompression sickness, also known as the bends, when they reduced their spacesuit pressures for the spacewalk.
Astronauts Bernard Harris, left, and Michael Foale during the spacesuit thermal testing part of their spacewalk. Foale, left, and Harris during the mass handling part of their spacewalk. Foale and Harris exited the airlock minutes after Voss safely stowed SPARTAN. With Titov operating the robotic arm, Harris and Foale climbed aboard its foot restraint to begin the first phase of the spacewalk, testing modifications to the spacesuits for their thermal characteristics. Titov lifted them well above the payload bay and the two spacewalkers stopped moving for about 15 minutes, until their hands and feet got cold. The spacewalk then continued into its second portion, the mass handling activity. Titov steered Foale above the SPARTAN where he lifted the satellite up and handed it off to Harris anchored in the payload bay. Harris then moved it around in different directions to characterize handling of the 2,600-pound satellite. Foale and Harris returned to the airlock after a spacewalk lasting 4 hours 39 minutes.
The STS-63 astronauts pose for their inflight crew photo. Discovery makes a successful landing at NASA’s Kennedy Space Center in Florida. The day following the spacewalk, the STS-63 crew finished the science experiments, closed down the Spacehab module, and held a news conference with reporters on the ground. Wetherbee and Collins tested Discovery’s thrusters and aerodynamic surfaces in preparation for the following day’s reentry and landing. The next day, on Feb. 11, they closed Discovery’s payload bay doors and put on their launch and entry suits. Wetherbee guided Discovery to a smooth landing on Kennedy’s Shuttle Landing Facility, ending the historic mission after eight days, six hours, and 28 minutes. They orbited the Earth 129 times. The mission paved the way for nine shuttle dockings with Mir beginning with STS-71, and 37 with the International Space Station. Workers at Kennedy towed Discovery to the processing facility to prepare it for its next mission, STS-70 in July 1995.
Over the next three years, Wetherbee, Collins, Foale, and Titov all returned to Mir during visiting shuttle flights, with Foale staying aboard as the NASA-5 long-duration crew member. Between 2001 and 2005, Wetherbee, Collins, and Foale also visited the International Space Station. Wetherbee commanded two assembly flights, Collins commanded the return to flight mission after the Columbia accident, and Foale commanded Expedition 8.
Enjoy the crew narrate a video about their STS-63 mission.
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By NASA
Explore Hubble Hubble Home Overview About Hubble The History of Hubble Hubble Timeline Why Have a Telescope in Space? Hubble by the Numbers At the Museum FAQs Impact & Benefits Hubble’s Impact & Benefits Science Impacts Cultural Impact Technology Benefits Impact on Human Spaceflight Astro Community Impacts Science Hubble Science Science Themes Science Highlights Science Behind Discoveries Hubble’s Partners in Science Universe Uncovered Explore the Night Sky Observatory Hubble Observatory Hubble Design Mission Operations Missions to Hubble Hubble vs Webb Team Hubble Team Career Aspirations Hubble Astronauts News Hubble News Hubble News Archive Social Media Media Resources Multimedia Multimedia Images Videos Sonifications Podcasts e-Books Online Activities Lithographs Fact Sheets Posters Hubble on the NASA App Glossary More 35th Anniversary Online Activities 2 min read
Hubble Spots a Supernova
This NASA/ESA Hubble Space Telescope image features a supernova in the constellation Gemini. ESA/Hubble & NASA, R. J. Foley (UC Santa Cruz) The subject of this NASA/ESA Hubble Space Telescope image is a supernova-hosting galaxy located about 600 million light-years away in the constellation Gemini. Hubble captured this image roughly two months after a supernova named SN 2022aajn was discovered. The supernova is visible as a blue dot at the center of the image, brightening the hazy body of the galaxy.
Other than the announcement of its discovery in November 2022, SN 2022aajn has never been the subject of published research. Why then would Hubble observe this supernova? SN 2022aajn is what’s known as a Type Ia supernova, which results from the explosion of the core of a dead star. Supernovae of this type help astronomers measure the distance to faraway galaxies. This is possible because Type Ia supernovae have the same intrinsic luminosity — no matter how bright they seem from Earth, they put out the same amount of light as other Type Ia supernovae. By comparing the observed brightness to the known intrinsic brightness, researchers can calculate the distance to the supernova and its host galaxy.
This seemingly simple way of measuring distances is complicated by cosmic dust. The farther away a supernova is, the fainter and redder it will appear — but intergalactic dust can make a supernova appear fainter and redder as well. To understand this complication, researchers will use Hubble to survey a total of 100 Type Ia supernovae in seven wavelength bands from ultraviolet to near-infrared. This image combines data taken at four infrared wavelengths. Infrared light passes through dust more easily than visible or ultraviolet light. By comparing the brightness of the sampled supernovae across different wavelengths, researchers can disentangle the effects of dust and distance, helping to improve measurements of galaxies billions of light-years away.
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The Death Throes of Stars
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Last Updated Jan 30, 2025 Editor Andrea Gianopoulos Location NASA Goddard Space Flight Center Related Terms
Hubble Space Telescope Astrophysics Astrophysics Division Galaxies Goddard Space Flight Center Stars Supernovae Keep Exploring Discover More Topics From NASA
Hubble Space Telescope
Since its 1990 launch, the Hubble Space Telescope has changed our fundamental understanding of the universe.
Hubble’s Night Sky Challenge
Reshaping Our Cosmic View: Hubble Science Highlights
Hubble’s 35th Anniversary
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By NASA
On Jan. 24, 1985, space shuttle Discovery took off from NASA’s Kennedy Space Center (KSC) in Florida on STS-51C, the first space shuttle mission entirely dedicated to the Department of Defense (DOD). As such, many of the details of the flight remain classified. Discovery’s crew of Commander Thomas “T.K.” Mattingly, Pilot Loren Shriver, Mission Specialists Ellison Onizuka and James Buchli, and Payload Specialist Gary Payton deployed a classified satellite that used an Inertial Upper Stage (IUS) to reach its final geostationary orbit. The three-day mission ended with a landing at KSC. Postflight inspection of the Solid Rocket Boosters (SRBs) revealed the most significant erosion of O-ring seals seen in the shuttle program up to that time, attributed to unusually cold weather before and during launch.
The STS-51C crew of Pilot Loren Shriver, seated left, and Commander Thomas “T.K.” Mattingly; Payload Specialist Gary Payton, standing left, and Mission Specialists James Buchli and Ellison Onizuka. The STS-51C crew patch. In October 1982, NASA assigned astronauts Mattingly, Shriver, Onizuka, and Buchli as the STS-10 crew for a dedicated DOD flight aboard Challenger then scheduled for September 1983. Payton joined the crew as a payload specialist in the summer of 1983 with Keith Wright assigned as his backup. The failure of the IUS on STS-6 in April 1983 delayed the STS-10 mission, that also used the IUS, until engineers could identify and fix the cause of the problem. By September 1983, NASA had remanifested the crew and the payload on STS-41F with a July 1984 launch, that changed to STS-41E by November 1983. Additional delays in fixing the IUS delayed the mission yet again, by June 1984 redesignated as STS-51C and slated for December 1984 aboard Challenger.
STS-51C marked the third spaceflight for Mattingly, selected in 1966 as part of NASA’s fifth group of astronauts. He served on the prime crew for Apollo 13 until exposure to German measles forced his last-minute replacement by his backup. He then flew on Apollo 16 and STS-4. For Shriver, Onizuka, and Buchli, all three selected as astronauts in the class of 1978, STS-51C marked their first trip into space. The U.S. Air Force selected Payton and Wright in August 1979 in its first class of Manned Spaceflight Engineers, and STS-51C marked Payton’s first and only space mission.
In November 1984, NASA decided to delay STS-51C from December 1984 to January 1985 and swap orbiters from Challenger to Discovery. Postflight inspections following Challenger’s STS-41G mission in October 1984 revealed degradation of the bonding materials holding thermal protection system tiles onto the orbiter, requiring the replacement of 4,000 tiles. The time required to complete the work precluded a December launch. Tests conducted on Discovery prior to its November STS-51A mission revealed the bonding material to be sound.
Space shuttle Discovery rolls out to Launch Pad 39A. The STS-51C crew poses during launch pad evacuation drills associated with the Terminal Countdown Demonstration Test. The STS-51C crew exits crew quarters for the ride to Launch Pad 39A. On Jan. 5, 1985, Discovery rolled out from KSC’s Vehicle Assembly Building, where workers mated it with its External Tank (ET) and SRBs, to Launch Pad 39A. There, engineers conducted the Terminal Countdown Demonstration Test, essentially a dress rehearsal for the actual countdown, on Jan. 6-7, with the crew participating in the final few hours much as they would on launch day. The astronauts returned to KSC on Jan. 20 to prepare for the planned launch on Jan. 23. The day before, NASA managers decided to delay the launch by one day due to unseasonably cold weather, with concern about sub-freezing temperatures causing ice to form on the ET and possibly coming loose during ascent and damaging the vehicle. The DOD had requested that NASA keep the actual launch time secret until T minus nine minutes, with most of the countdown taking place hidden from public view.
Liftoff of space shuttle Discovery on STS-51C. Liftoff of Discovery on its third mission, STS-51C, came at 2:50 p.m. EST on Jan. 24, beginning the 15th space shuttle flight. Eight and a half minutes later, Discovery and its five-man crew had reached orbit. And, at the DOD customer’s request, all public coverage of the mission ended. Although NASA could not reveal the spacecraft’s orbital parameters, trade publications calculated that Discovery first entered an elliptical orbit, circularized over the next few revolutions, prior to Onizuka deploying the IUS and payload combination on the seventh orbit. Neither NASA nor the DOD have released any imagery of the deployment or even of the payload bay, with only a limited number of in-cabin and Earth observation photographs made public.
STS-51C Commander Thomas “T.K.” Mattingly films the Earth from Discovery’s overhead flight deck window. STS-51C crew members Loren Shriver, left, Ellison Onizuka, and James Buchli on Discovery’s flight deck. STS-51C Payload Specialist Gary Payton on Discovery’s flight deck. Sunlight streams through Earth’s upper atmosphere, with Discovery’s tail and Orbital Maneuvering Engine pods outlined by sunlight. The Pacific coast of Guatemala and southern Mexico. New Orleans and the Mississippi River delta. Discovery touches down at NASA’s Kennedy Space Center in Florida. The STS-51C astronauts are greeted by NASA officials as they exit Discovery. To maintain the mission’s secrecy, NASA could reveal the touchdown time only 16 hours prior to the event. On Jan. 27, Mattingly and Shriver brought Discovery to a smooth landing at KSC’s Shuttle Landing Facility after a flight of three days one hour 33 minutes, the shortest space shuttle mission except for the first two orbital test flights. The astronauts orbited the Earth 49 times. About an hour after touchdown, the astronaut crew exited Discovery and boarded the Astrovan for the ride back to crew quarters. Neither NASA management nor the astronauts held a post mission press conference. The U.S. Air Force announced only that the “IUS aboard STS-51C was deployed from the shuttle Discovery and successfully met its mission objectives.” Later in the day, ground crews towed Discovery to the Orbiter Processing Facility to begin preparing it for its next planned mission, STS-51D in March.
Postscript
Following the recovery of SRBs after each shuttle mission, engineers conducted detailed inspections before clearing them for reuse. After STS-51C, inspections of the critical O-ring seals that prevented hot gases from escaping from the SRB field joints revealed significant erosion and “blow-by” between the primary and secondary O-rings. Both left and right hand SRBs showed this erosion, the most significant of the program up to that time. Importantly, these O-rings experienced weather colder than any previous shuttle mission, with overnight ambient temperatures in the teens and twenties. Even at launch time, the O-rings had reached only 60 degrees. Engineers believed that these cold temperatures made the O-rings brittle and more susceptible to erosion. One year later, space shuttle Challenger launched after similarly cold overnight temperatures, with O-rings at 57 degrees at launch time. The Rogers Commission report laid the blame of the STS-51L accident on the failure of O-rings that allowed super-hot gases to escape from the SRB and impinge on the hydrogen tank in the ET, resulting in the explosion that destroyed the orbiter and claimed the lives of seven astronauts. The commission also faulted NASA’s safety culture for not adequately addressing the issue of O-ring erosion, a phenomenon first observed on STS-2 and to varying degrees on several subsequent missions.
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