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In July 1968, much work still remained to meet the goal President John F. Kennedy set in May 1961, to land a man on the Moon and return him safely to the Earth before the end of the decade. No American astronaut had flown in space since the November 1966 flight of Gemini XII, the delay largely a result of the tragic Apollo 1 fire. Although the Apollo spacecraft had successfully completed several uncrewed test flights, the first crewed mission still lay three months in the future. The delays in getting the Lunar Module (LM) ready for its first flight caused schedule concerns, but also presented an opportunity for a bold step to send the second crewed Apollo mission, the first crewed flight of the Saturn V, on a trip to orbit the Moon. Using an incremental approach, three flights later NASA accomplished President Kennedy’s goal.

view of fire damage to cm at pad 34apollo 4 launchmating of lm1 to sla nov 22 1967apollo 6 recoveryLeft: The charred remains of the Apollo 1 spacecraft following the tragic fire that claimed the lives of astronauts Virgil I. “Gus” Grissom, Edward H. White, and Roger B. Chaffee. Middle left: The first launch of the Saturn V rocket on the Apollo 4 mission. Middle right: The first Lunar Module in preparation for the Apollo 5 mission. Right: Splashdown of Apollo 6, the final uncrewed Apollo mission.

The American human spaceflight program suffered a jarring setback on Jan. 27, 1967, with the deaths of astronauts Virgil I. Grissom, Edward H. White, and Roger B. Chaffee in the Apollo 1 fire. The fire and subsequent Investigation led to wholesale changes to the spacecraft, such as the use of fireproof materials and redesign of the hatch to make it easy to open. The early Block I spacecraft, such as Apollo 1, would now only be used for uncrewed missions, with crews flying only aboard the more advanced Block II spacecraft. The fire and its aftermath also led to management changes. For example, George M. Low replaced Joseph F. Shea as Apollo Spacecraft Program Manager. The first Apollo mission after the fire, the uncrewed Apollo 4 in November 1967, included the first launch of the Saturn V Moon rocket as well as a 9-hour flight of a Block I Command and Service Module (CSM). Apollo 5 in January 1968 conducted the first uncrewed test of the LM, and despite a few anomalies, managers considered it successful enough that they canceled a second uncrewed flight. The April 1968 flight of Apollo 6, planned as a near-repeat of Apollo 4, encountered several significant anomalies such as first stage POGO, or severe vibrations, and the failure of the third stage to restart, leading to an alternate mission scenario. Engineers devised a solution to the POGO problem and managers decided that the third flight of the Saturn V would carry a crew.

apollo 7 water egress training aug 5 1968apollo 7 stackingapollo 7 crew outside simulator kscLeft: Apollo 7 astronauts R. Walter Cunningham, left, Donn F. Eisele, and Walter M. Schirra participate in water egress training. Middle: Workers stack the Apollo 7 spacecraft on its Saturn IB rocket at Launch Pad 34. Right: Schirra, left, Cunningham, and Eisele stand outside the spacecraft simulator.

As of July 1968, NASA’s plan called for two crewed Apollo flights in 1968 and up to five in 1969 to achieve the first lunar landing to meet President Kennedy’s deadline, with each mission incrementally building on the success of the previous ones. The first mission, Apollo 7, would return American astronauts to space following a 23-month hiatus. Planned for October 1968, the crew of Walter M. Schirra, Donn F. Eisele, and R. Walter Cunningham would launch atop a Saturn IB rocket and conduct a shakedown flight of the Block II CSM in Earth orbit, including testing the Service Propulsion System engine, critical on later lunar missions for getting into and out of lunar orbit. The flight plan remained open-ended, but managers expected to complete a full-duration 11-day mission, ending with a splashdown in the Atlantic Ocean. Preparations for Apollo 7 proceeded well during the summer of 1968. Workers had stacked the two-stage Saturn IB rocket on Launch Pad 34 back in April. In KSC’s Manned Spacecraft Operations Building (MSOB), Schirra, Eisele, and Cunningham completed altitude chamber tests of their spacecraft, CSM-101, on July 26 followed by their backups three days later. Workers trucked the spacecraft to the launch pad on Aug. 9 for mating with the rocket. Among major milestones, Schirra, Eisele, and Cunningham completed water egress training in the Gulf of Mexico on Aug. 5, in addition to spending time in the spacecraft simulators at KSC and at the Manned Spacecraft Center (MSC), now NASA’s Johnson Space Center in Houston.

apollo 9 crew during training jun 19 1968lm 3 arrives ksc super guppys ii stacking jul 24 1968Left: The original Apollo 8 crew of Russell L. Schweickart, left, David R. Scott, and James A. McDivitt during training in June 1968. Middle: Lunar Module-3 arrives at NASA’s Kennedy Space Center (KSC) in Florida in June 1968. Right: In July 1968, workers in KSC’s Vehicle Assembly Building stack the Saturn V rocket for the Apollo 8 mission.

The second flight, targeting a December 1968 launch, would feature the first crewed launch of the Saturn V rocket. The Apollo 8 crew of James A. McDivitt, David R. Scott, and Russell L. Schweickart would conduct the first crewed test of the LM in the relative safety of low Earth orbit. McDivitt and Schweickart would fly the LM on its independent mission, including separating the ascent stage from the descent stage to simulate a takeoff from the Moon, while Scott remained in the CSM. After redocking, Schweickart would conduct a spacewalk to practice an external transfer between the two vehicles. Workers completed stacking the three-stage Saturn V rocket (SA-503) in KSC’s Vehicle Assembly Building (VAB) on Aug. 14. The first component of the spacecraft, LM-3, arrived at KSC on June 9, while CSM-103, arrived on Aug. 12. Workers in the MSOB began to prepare both spacecraft for flight.

borman collins anders crew mar 1968lm 3 in msob aug 27 1968apollo 8 rollout oct 9 1968Left: The original Apollo 9 crew of William A. Anders, left, Michael Collins, and Frank Borman during training in March 1968. Middle: Lunar Module-3 during preflight processing at NASA’s Kennedy Space Center (KSC) in Florida in August 1968. Right: Following the revision of the mission plans for Apollo 8 and 9 and crew changes, the Apollo 8 crew of James A. Lovell, Anders, and Borman stand before their Saturn V rocket as it rolls out of KSC’s Vehicle Assembly Building in October 1968.

The third flight, planned for early 1969, and flown by Frank Borman, Michael Collins, and William A. Anders, would essentially repeat the Apollo 8 mission, but at the end would fire the SPS engine to raise the high point of their orbit to 4,600 miles and then simulate a reentry at lunar return velocity to test the spacecraft’s heat shield. On July 23, Collins underwent surgery for a bone spur in his neck, and on August 8, NASA announced that James A. Lovell from the backup crew would take his place. Later missions in 1969 would progress to sending the CSM and LM combination to lunar orbit, leading to the first landing before the end of the year. Construction of the rocket and spacecraft components for these future missions continued at various contractor facilities around the country.

kraft gilruth low in mcc during apollo 6slayton portraitdebus portraitvon braun portraitLeft: In Mission Control during the Apollo 6 mission, Director of Flight Crew Operations Christopher C. Kraft, left, Director of the Manned Spacecraft Center, now NASA’s Johnson Space Center in Houston Robert R. Gilruth, and Apollo Spacecraft Program Manager George M. Low. Middle left: Chief of Flight Crew Operations Donald K. “Deke” Slayton. Middle right: Director of NASA’s Kennedy Space Center in Florida Kurt H. Debus. Right: Director of NASA’s Marshall Space Flight Center in Huntsville, Alabama.

Challenges to this plan began to arise in June 1968. Managers’ biggest concern centered around the readiness of LM-3. After its delivery to KSC on June 9, managers realized the vehicle needed much more work than anticipated and it would not meet the planned December Apollo 8 launch date. Best estimates put its flight readiness no earlier than February 1969. That kind of delay would jeopardize meeting President Kennedy’s fast-approaching deadline. To complicate matters, intelligence reports indicated that the Soviets were close to sending cosmonauts on a trip around the Moon, possibly before the end of the year, and also preparing to test a Saturn V-class rocket for a Moon landing mission.

Apollo Spacecraft Program Manager Low formulated a plan both audacious and risky. Without a LM, an Earth orbital Apollo 8 mission would simply repeat Apollo 7’s and not advance the program very much. By sending the CSM on a mission around the Moon, or even to orbit the Moon, NASA would gain valuable experience in navigation and communications at lunar distances. To seek management support for his plan, on Aug. 9 Low met with MSC Director Robert R. Gilruth, who supported the proposal. They called in Christopher C. Kraft, director of flight operations, for his opinion. Two days earlier, Low had asked Kraft to assess the feasibility of a lunar orbit mission for Apollo 8, and Kraft deemed it achievable from a ground control and spacecraft computer standpoint. Chief of Flight Crew Operations Donald K. “Deke” Slayton joined the discussion, and all agreed to seek support for the plan from the directors of KSC and of NASA’s Marshall Space Flight Center (MSFC) in Huntsville, Alabama, as well as NASA Headquarters (HQ) in Washington, D.C. That afternoon, the four flew to Huntsville and met with MSFC Director Wernher von Braun, KSC Director Kurt H. Debus, and HQ Apollo Program Director Samuel C. Phillips. By the end of the meeting, the group identified no insurmountable technical obstacles to the lunar mission plan, with the qualification that the Apollo 7 mission in October concluded successfully. Von Braun had confidence that the Saturn V would perform safely, and Debus believed KSC could support a December launch.

Slayton called Borman, who was with Lovell and Anders conducting tests with their spacecraft in Downey, California. He ordered Borman to immediately fly to Houston, where he offered him command of the new circumlunar Apollo 8 mission, which Borman accepted. His crew would swap missions with McDivitt’s, who agreed to fly an Earth orbital test of the LM in February 1969, putting that crew’s greater experience with the LM to good use. The training challenge fell on Borman’s crew, who now had just four months to train for a flight around the Moon.

samuel phillips portraitgeorge mueller portraitpaine portrait w lmjames webb portraitLeft: Apollo Program Director Samuel C. Phillips. Middle left: Associate Administrator for Manned Space Flight George E. Mueller. Middle right: Deputy Administrator Thomas O. Paine. Right: Administrator James E. Webb.

On Aug. 14, representatives from MSC, MSFC, and KSC attended a meeting in Washington with NASA Deputy Administrator Thomas O. Paine and Apollo Program Director Phillips, the senior Headquarters officials present as NASA Administrator James E. Webb and Associate Administrator for Manned Space Flight George E. Mueller attended a conference in Vienna. The group discussed Low’s proposal and agreed on the technical feasibility of accomplishing a circumlunar flight with Apollo 8 in December. During the discussion, Mueller happened to call from Vienna and when they presented him with the proposal, he was at first reticent, especially since NASA had yet to fly Apollo 7. He requested more information and more time to consider the proposal so he could properly brief Webb. Paine then polled each center director for his overall assessment. Von Braun, who designed the Saturn V rocket, stated that whether it went to the Moon or stayed in Earth orbit didn’t matter too much. Debus stated that KSC could support a Saturn V launch in December – as noted above, his team was already processing both the rocket and the spacecraft. Gilruth agreed that the proposal represented a key step in achieving President Kennedy’s goal, and emphasized that the mission should not just loop around the Moon but actually enter orbit. Following additional discussions after Webb’s return from Vienna, he agreed to the plan, but would not make a formal decision until after a successful Apollo 7 flight in October. NASA kept the lunar orbit plan quiet even as the crews began training for their respective new missions. An announcement on Aug. 19 merely stated that Apollo 8 would not carry a LM, as the agency continued to assess various mission objectives. Ultimately, the plan required President Lyndon B. Johnson’s approval.

llrv 1 accident may 6 1968 armstrong ejectinglta8 test irwin bull mar 2 1968apollo 2tv-1 testingapollo parachute testing at el centro jun 16 1968Left: Astronaut Neil A. Armstrong ejects just moments before his Lunar Landing Research Vehicle crashed. Middle left: Pilot Gerald P. Gibbons, left, and astronaut James B. Irwin prepare to enter an altitude chamber for one of the Lunar Module Test Article-8 (LTA-8) vacuum tests. Middle right: Astronauts Joe H. Engle, left, Vance D. Brand, and Joseph P. Kerwin preparing for the 2TV-1 altitude test. Right: One of the final Apollo parachute tests.

As those discussions took place, work around the country continued to prepare for the first lunar landing, not without some setbacks. On May 8, astronaut Neil A. Armstrongejected just in the nick of time as the Lunar Landing Research Vehicle (LLRV) he was piloting went out of control and crashed. Managers suspended flights of the LLRV and its successor, the Lunar Landing Training Vehicle (LLTV), until Oct. 3. Astronauts used the LLRV and LLTV to train for the final few hundred feet of the descent to the Moon’s surface. On May 27, astronaut James B. Irwin and pilot Gerald P. Gibbons began a series of altitude tests in Chamber B of the Space Environment Simulation Laboratory (SESL) at MSC. The tests, using the LM Test Article-8 (LTA-8), evaluated the pressure integrity of the LM as well as the new spacesuits designed for the Apollo program. The first series of LTA-8 tests supported the Earth-orbital flight of LM-3 on Apollo 9 while a second series in October and November supported the LM-5 flight of Apollo 11, the first lunar landing mission. In June, using SESL’s Chamber A, astronauts Joseph P. Kerwin, Vance D. Brand, and Joe H. Engle completed an eight-day thermal vacuum test using the Apollo 2TV-1 spacecraft to certify the vehicle for Apollo 7. A second test in September certified the vehicle for lunar missions. July 3 marked the final qualification drop test of the Apollo parachute system, a series begun five years earlier. The tests qualified the parachutes for Apollo 7.

History records that Apollo 11 accomplished the first human landing on the Moon in July 1969. It is remarkable to think that just one year earlier, with the agency still recovering from the Apollo 1 fire, NASA had not yet flown any astronauts aboard an Apollo spacecraft. And further, the agency took the bold step to plan for a lunar orbital mission on just the second crewed mission. With a cadence of a crewed Apollo flight every two months between October 1968 and July 1969, NASA accomplished President Kennedy’s goal of landing a man on the Moon and returning him safely to the Earth.

John Uri
NASA Johnson Space Center

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      Schematic showing the Hubble Space Telescope’s major components. Workers inspect the Hubble Space Telescope’s 94-inch diameter primary mirror prior to assembly. Astronauts release the Hubble Space Telescope in April 1990 during the STS-31 mission. The discovery after the Hubble Space Telescope’s launch in 1990 that its primary mirror suffered from a flaw called spherical aberration disappointed scientists who could not obtain the sharp images they had expected. But thanks to the Hubble’s built-in feature of on-orbit servicing, NASA devised a plan to correct the telescope’s optics during the first planned repair mission in 1993. A second servicing mission in 1997 upgraded the telescope’s capabilities until the next mission planned for three years later. But after three of the telescope’s six gyroscopes failed in 1997, 1998, and 1999, mission rules dictated a call up mission in case additional gyroscope failures sent Hubble into a safe mode. NASA elected to move up some of the servicing tasks from the third mission, splitting it into missions 3A and 3B, planning to fly 3A in October 1999 on Discovery’s STS-103 mission primarily to replace the failed gyroscopes. Delays to the shuttle fleet resulting from anomalies during the launch of STS-93 in July 1993 slipped STS-103 first into November and ultimately into December. Technical issues with Discovery itself pushed the launch date to mid-December, and raised concerns about having a shuttle in orbit during the Y2K transition. Once the launch had slipped to Dec. 19, mission planners cut the mission from 10 to eight days, deleting one of the four spacewalks, to ensure a return before the end of the calendar year. The servicing mission couldn’t come soon enough, as a fourth gyroscope failed aboard Hubble in mid-November, with Discovery already poised on the launch pad to prepare for STS-103. Controllers placed Hubble in a safe mode until the astronauts arrived.
      The STS-103 crew of C. Michael Foale, left, Claude Nicollier, Scott J. Kelly, Curtis L. Brown, Jean-François A. Clervoy, John M. Grunsfeld, and Steven L. Smith. The STS-103 crew patch. The mission patch for the Hubble Servicing Mission-3A. To execute the third Hubble Servicing Mission, in July 1998 NASA selected an experienced four-person team to carry out a record-breaking six spacewalks on the flight then planned for June 2000. The spacewalkers included Mission Specialists Steven L. Smith serving as payload commander, John M. Grunsfeld, C. Michael Foale, and European Space Agency (ESA) astronaut Claude Nicollier from Switzerland. The addition in March 1999 of Commander Curtis L. Brown, Pilot Scott J. Kelly, and Mission Specialist ESA astronaut Jean-François A. Clervoy of France rounded out the highly experienced crew with 18 previous spaceflights among them. Brown earned the distinction as only the fifth person to fly in space six times. For Kelly, STS-103 marked his first spaceflight. Smith, Clervoy, and Grunsfeld each had flown two previous missions, Foale four including a long-duration mission aboard Mir, and Nicollier three. Smith participated in three spacewalks during the second Hubble Servicing Mission and Nicollier served as the Remote Manipulator System (RMS) or robotic arm operator during the first.
      The STS-103 crew at the traditional prelaunch breakfast at NASA’s Kennedy Space Center in Florida. Suited up, the STS-103 astronauts leave crew quarters for the trip to Launch Pad 39B. Space shuttle Discovery on Launch Pad 39B, awaiting launch. Discovery arrived back to KSC at the end of the STS-96 mission on June 6, 1999, and workers towed it to the Orbiter Processing Facility the same day to begin readying it for STS-103. The vehicle rolled over to the Vehicle Assembly Building on Nov. 4, where workers mated it with its external tank and twin solid rocket boosters, before rolling the stack out to Launch Pad 39B on Nov. 13.
      Liftoff of space shuttle Discovery on the STS-103 Hubble Space Telescope servicing mission 3A. The Hubble Space Telescope as Discovery approaches. The STS-103 crew berthing the Hubble into the payload bay. Beginning its 27th trip into space, Discovery lifted off from Launch Pad 39B at 7:50 p.m. EST on Dec. 19 to fix the ailing space telescope. Two days later, Brown and Kelly maneuvered Discovery to within range of Hubble so Clervoy operating the 50-foot-long RMS could grapple the telescope and berth it into the payload bay.
      During the first spacewalk, astronauts John M. Grunsfeld, left, and Steven L. Smith replacing one of the Rate Sensor Units containing two gyroscopes. Smith gives a thumbs up with his image reflected in the Hubble Space Telescope. Smith and Grunsfeld conducted the mission’s first spacewalk on Dec. 22, the flight’s fourth day in space. The duo, aided by Clervoy operating the RMS from inside Discovery, completed two of mission’s highest priority objectives. They replaced the failed gyroscopes, installing three new Rate Sensor Units, each containing two gyroscopes, to return control to the ailing telescope. They also installed six Voltage/Temperature Improvement Kits to prevent the telescope’s batteries from overheating as they aged. The excursion lasted eight hours 15 minutes, at the time the second longest spacewalk.
      During the second spacewalk, astronauts C. Michael Foale, left, and Claude Nicollier during the changeout of the fine guidance sensor. Foale at the end of the Remote Manipulator System services the Hubble Space Telescope. The next day, Nicollier and Foale conducted the mission’s second spacewalk. The main task for this excursion involved installing a new computer aboard Hubble, replacing the original 1970s vintage unit. The new radiation-hardened system ran 20 times faster and carried six times more memory while using one-third the electrical power. They also installed a fine guidance sensor before concluding the eight-hour 10-minute spacewalk.
      Astronauts Steven L. Smith, left, and John M. Grunsfeld begin their servicing activities during the third spacewalk. At the end of the third and final spacewalk, Grunsfeld, left, and Smith provide closing comments about the work the mission accomplished to service the Hubble Space Telescope. Smith and Grunsfeld ventured outside for a second time to complete the flight’s third and final spacewalk on Dec. 24, the first spacewalk conducted on Christmas Eve day. First, they replaced an old reel-to-reel tape recorder with a solid state unit providing a 10-fold increase in recording capability and replaced a failed data transmitter. They installed seven new covers on Hubble’s electronics bay doors for added protection of the telescope’s insulation. This third spacewalk lasted eight hours eight minutes.
      The first space shuttle crew to celebrate Christmas in space, the STS-103 astronauts pose wearing Santa hats. The Hubble Space Telescope shortly after the STS-103 crew released it. The next day, the STS-103 astronauts earned the distinction as the first space shuttle crew to spend Christmas Day in space. Clervoy grappled Hubble, lifted it out of the payload bay and released it to continue its mission. Hubble Space Telescope Program Manager John H. Campbell said after the release, “The spacecraft is being guided by its new gyros under the control of its brand new computer. [It] is now orbiting freely and is in fantastic shape.” After deploying Hubble, the astronauts enjoyed a well-deserved Christmas dinner, with Clervoy providing French delicacies. The crew spent Dec. 26 readying Discovery for its return to Earth, including testing its reaction control system thrusters and aerodynamic surfaces and stowing unneeded gear.
      Astronauts Steven L. Smith, left, Claude Nicollier, and John M. Grunsfeld complete their fluid loading protocol and put on their launch and entry suits prior to reentry. Space shuttle Discovery makes a perfect night landing at NASA’s Kennedy Space Center in Florida. The crew welcome home ceremony at Ellington Field in Houston. On Dec. 27, the astronauts donned their launch and entry suits and prepared for the return to Earth. They closed the payload bay doors and fired Discovery’s engines to bring them out of orbit. Just before landing, Kelly lowered the craft’s landing gear and Brown guided Discovery to a smooth night landing at KSC, concluding a flight of seven days, 23 hours, 11 minutes. They circled the Earth 119 times. The flight marked Discovery’s last solo flight as all its subsequent missions docked with the International Space Station. Workers at KSC began readying it for its next mission, STS-92 in October 2000.

      The Hubble Space Telescope continues to operate today, far exceeding the five-year life extension expected from the last of the servicing missions in 2009. Joined in space by the James Webb Space Telescope in 2021, the two instruments together continue to image the skies across a broad range of the electromagnetic spectrum to provide scientists with the tools to gain unprecedented insights into the universe and its formation.

      Watch the STS-103 crew narrate a video of their Hubble servicing mission.
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