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30 Years Ago: STS-61, the First Hubble Servicing Mission

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“Trying to do stellar observations from Earth is like trying to do birdwatching from the bottom of a lake.”  James B. Odom, Hubble Program Manager 1983-1990.

The discovery after its launch that the Hubble Space Telescope’s primary mirror suffered from a flaw 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. The agency assigned one of its most experienced crews to undertake the complex tasks, naming Richard O. Covey, Kenneth D. Bowersox, Kathryn C. Thornton, Claude Nicollier of the European Space Agency, Jeffrey A. Hoffman, F. Story Musgrave, and Thomas D. Akers to the STS-61 first Hubble Servicing Mission. The first all veteran crew since the STS-26 return to flight mission in 1988 had a cumulative 16 previous missions among them and all had previous spacewalking experience. During their 11-day flight in December 1993, they repaired the telescope during an unprecedented five spacewalks in a single space shuttle mission, rendering it more capable than originally designed.

The STS-61 crew of Kenneth D. Bowersox, sitting left, Kathryn C. Thornton, F. Story Musgrave, and Claude Nicollier of the European Space Agency; Richard O. Covey, standing left, Jeffrey A. Hoffman, and Thomas D. Akers The STS-61 crew patch Endeavour rolls over from Launch Pad 39A to 39B at NASA’s Kennedy Space Center in Florida
Left: The STS-61 crew of Kenneth D. Bowersox, sitting left, Kathryn C. Thornton, F. Story Musgrave, and Claude Nicollier of the European Space Agency; Richard O. Covey, standing left, Jeffrey A. Hoffman, and Thomas D. Akers. Middle: The STS-61 crew patch. Right: Endeavour rolls over from Launch Pad 39A to 39B at NASA’s Kennedy Space Center in Florida.

The first Hubble servicing mission proved to be one of the most complex up to that time. With that in mind, on March 16, 1992, NASA named Musgrave, an astronaut since 1967 and a veteran of four previous missions including conducting the first spacewalk of the shuttle era, as the payload commander and one of the four spacewalkers for STS-61. On Aug. 28, NASA named Hoffman, Akers, and Thornton as the other three spacewalkers who in teams of two would carry out the five spacewalks on alternating days. Finally, on Dec. 3, NASA named Covey, Bowersox, and Nicollier as the commander, pilot, and flight engineer, respectively, for the mission. Nicollier also served as the prime operator of the Remote Manipulator System (RMS), or robotic arm, with Bowersox as his backup. The seven-person crew trained intensely for the next year preparing for the complex tasks ahead, including simulating the spacewalks at the Neutral Buoyancy Simulator at NASA’s Marshall Space Flight Center in Huntsville, Alabama, and the Weightless Environment Training Facility at NASA’s Johnson Space Center in Houston. Meanwhile, at NASA’s Kennedy Space Center in Florida, workers prepared space shuttle Endeavour for its fifth journey into space. They rolled the shuttle, assembled with its external tank and solid rocket booster, to Launch Pad 39A on Oct. 28. However, following a wind storm on Oct. 30 that contaminated the payload changeout room with sandy grit, managers decided to move Endeavour to neighboring Pad B on Nov. 15, in only the second roll around in shuttle history.

Schematic of 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
Left: Schematic of the Hubble Space Telescope’s major components. Middle: Workers inspect the Hubble Space Telescope’s 94-inch diameter primary mirror prior to assembly. Right: Astronauts release the Hubble Space Telescope in April 1990 during the STS-31 mission.

The first concrete plan for placing an optical telescope in space, above the obscuring and distorting effects of the Earth’s atmosphere, originated with Princeton University astronomer Lyman S. Spitzer in 1946. In 1972, NASA first proposed a plan to launch a Large Space Telescope (LST) and five years later Congress approved the funding. As envisioned, the LST would contain a 94-inch diameter primary mirror and launch on the space shuttle, then still under development, in 1983. With an expected on-orbit lifetime of 15 years, the LST’s instruments would make observations primarily in the visible and ultraviolet parts of the electromagnetic spectrum. In 1983, managers abandoned the original plan to use the space shuttle to return the telescope to Earth for refurbishment and relaunch in favor of in-orbit maintenance and upgrades by astronauts during spacewalks in the shuttle’s payload bay. The same year, NASA renamed the LST after astronomer Edwin P. Hubble and set the launch for October 1986. The Challenger accident in January 1986 delayed the launch of the Hubble Space Telescope until April 24, 1990, during Discovery’s STS-31 mission. The shuttle flew to an unusually high 380-mile orbit to ensure that Hubble would operate above as much of the Earth’s atmosphere as possible. After initial on-orbit activation and checkout of the telescope’s systems, it was time for the much-anticipated “first light” images. The initial images, however, puzzled scientists as they showed stars not as single well-focused points of light but as blurred and fuzzy. Investigators learned that the telescope’s primary mirror suffered from a production error, its edges too flat by 0.003 mm, resulting in an optical problem called spherical aberration. While this significantly degraded the capability of several of Hubble’s instruments to return exceptionally detailed photographs, the telescope still produced some good images. NASA put in place a plan to fix the Hubble’s optical problems without resorting to repairing the mirror. With the spherical aberration well-defined, engineers designed a set of mirrors that astronauts could place aboard Hubble during the previously planned first servicing mission.

Liftoff of space shuttle Endeavour on the STS-61 mission to repair the Hubble Space Telescope The Hubble Space Telescope as seen from Endeavour during the rendezvous, with the end of the Remote Manipulator System (RMS), or robotic arm, visible at lower right On the shuttle’s flight deck, European Space Agency astronaut Claude Nicollier operates the RMS to grapple Hubble
Left: Liftoff of space shuttle Endeavour on the STS-61 mission to repair the Hubble Space Telescope. Middle: The Hubble Space Telescope as seen from Endeavour during the rendezvous, with the end of the Remote Manipulator System (RMS), or robotic arm, visible at lower right. Right: On the shuttle’s flight deck, European Space Agency astronaut Claude Nicollier operates the RMS to grapple Hubble.

Planning for the first servicing mission to Hubble began in 1988, two years before the launch of the telescope. With the post-launch discovery of spherical aberration, the scope of the first servicing mission changed dramatically. The primary goal now focused on correcting the telescope’s optics to ensure that its onboard instruments could function as planned. Engineers developed the Corrective Optics Space telescope Axial Replacement (COSTAR), a tool to correct Hubble’s blurry vision, consisting of five pairs of corrective mirrors placed in front of the Faint Object Camera, the Faint Object Spectrograph, and the Goddard High Resolution Spectrograph (GHRS) instruments. Installing COSTAR required the removal of the High-Speed Photometer, the sacrifice of one instrument outweighed by the saving of the other three. The astronauts also replaced the original Wide Field Planetary Camera (WFPC) with the more advanced WFPC2 to improve the telescope’s ultraviolet performance. The WFPC2 carried its own corrective optics. The astronauts also replaced fuses and the telescope’s two solar arrays, one of which imparted vibrations that prevented precise pointing. On Dec. 2, 1993, space shuttle Endeavour lifted off from Pad 39B at 4:27 a.m. EST, after a one-day weather delay. Following insertion into an unusually high 360-mile orbit to reach Hubble, the astronauts began their initial on-orbit operations by opening the payload bay doors. The next day, Covey and Bowersox performed several engine burns as part of the rendezvous maneuvers. The astronauts checked out the rendezvous radar, the Ku-band antenna, the Canadian-built Remote Manipulator System (RMS) or robotic arm, and the spacesuits, and reduced the pressure inside the shuttle from 14.7 pounds per square inch (psi) to 10.2 psi in preparation for the upcoming spacewalks to reduce the pre-breathe time required to prevent decompression sickness or the bends.

Endeavour approach to the Hubble Space Telescope Hubble secured onto its flight support structure in Endeavour’s payload bay The STS-61 crew poses on Endeavour’s flight deck, with Hubble visible through the windows
Left: Endeavour continues its approach to the Hubble Space Telescope. Middle: Hubble secured onto its flight support structure in Endeavour’s payload bay. Right: The STS-61 crew poses on Endeavour’s flight deck, with Hubble visible through the windows.

On the third day, Covey brought Endeavour to within 30 feet of Hubble so Nicollier could grapple it with the RMS. Covey radioed Houston, “Endeavour has a firm handshake with Mr. Hubble’s telescope.” Nicollier berthed the giant telescope onto its turntable-like Flight Support System (FSS) in the shuttle’s payload bay. Nicollier then used the RMS cameras to perform an inspection of Hubble.

European Space Agency astronaut Claude Nicollier operates the shuttle’s Remote Manipulator System (RMS) or robotic arm in support of the spacewalks Astronaut F. Story Musgrave works on the Hubble Musgrave releases bolts on the replacement solar arrays
First spacewalk. Left: European Space Agency astronaut Claude Nicollier operates the shuttle’s Remote Manipulator System (RMS) or robotic arm in support of the spacewalks. Middle: Astronaut F. Story Musgrave works on the Hubble. Right: Near the end of the first spacewalk, Musgrave releases bolts on the replacement solar arrays.

With Nicollier operating the RMS as he did for all five spacewalks, Hoffman and Musgrave conducted the mission’s first excursion on flight day four. They replaced two sets of Rate Sensing Units that contain gyroscopes to orient the telescope and replaced electrical control units and fuse plugs, providing the telescope with six healthy gyroscopes. Musgrave and Hoffman prepared for the next day’s spacewalk by loosening bolts on the replacement solar arrays, stored in the forward part of the payload bay. The pair spent 7 hours and 54 minutes outside on this first spacewalk. The ground commanded the two existing solar arrays on the telescope to retract, and while one did so the second one did not due to a bent support rod.

Astronaut Kathryn C. Thornton, on the end of the Remote Manipulator System, releases Hubble’s old solar array that failed to retract properly The solar array drifting away from space shuttle Endeavour Thornton disconnects Hubble’s retracted solar array
Second spacewalk. Left: Astronaut Kathryn C. Thornton, on the end of the Remote Manipulator System, releases Hubble’s old solar array that failed to retract properly. Middle: The solar array drifting away from space shuttle Endeavour. Right: Thornton disconnects Hubble’s retracted solar array.

On flight day five, Thornton and Akers stepped outside for the mission’s second spacewalk, lasting 6 hours 36 minutes. The primary tasks revolved around replacing the telescope’s two solar arrays. First, they disconnected the array that would not retract as planned, working only at night since the array generated electricity when exposed to sunlight. With Thornton on the end of the RMS, she released the partially open array as Nicollier pulled her away. Bowersox fired thrusters to separate from the array, the plumes impinging on it causing it to flap like a giant bird. Thornton and Akers then connected one of the new arrays, rotated the telescope on its FSS, disconnected the other array, stowing it in the payload bay for return to Earth, and replaced it with a new one.

Astronauts Jeffrey A. Hoffman, left, and F. Story Musgrave have removed the old Wide Field Planetary Camera (WFPC) from Hubble, the black rectangle at upper left shows its former location With European Space Agency astronaut Claude Nicollier operating the Remote Manipulator System from inside the shuttle, Hoffman guides the new WFPC2 into position, with Musgrave ready to assist Musgrave, left, and Hoffman have installed WFPC2, the white triangle in the middle of the telescope, with Hoffman about to pick up WFPC1 temporarily stowed on the side of the payload bay and place it in its permanent location for return to Earth
Third spacewalk. Left: Astronauts Jeffrey A. Hoffman, left, and F. Story Musgrave have removed the old Wide Field Planetary Camera (WFPC) from Hubble, the black rectangle at upper left shows its former location. Middle: With European Space Agency astronaut Claude Nicollier operating the Remote Manipulator System from inside the shuttle, Hoffman guides the new WFPC2 into position, with Musgrave ready to assist. Right: Musgrave, left, and Hoffman have installed WFPC2, the white triangle in the middle of the telescope, with Hoffman about to pick up WFPC1 temporarily stowed on the side of the payload bay and place it in its permanent location for return to Earth.

On the sixth day, Hoffman and Musgrave took their turn outside for the mission’s third spacewalk. Their primary task involved the replacement of the original WFPC with the more advance WFPC2 instrument. With Nicollier controlling the RMS, Hoffman removed the WFPC1 from the telescope and temporarily stowed it on the side of the payload bay. He then removed WFPC2 from its stowage location and he and Musgrave installed it into the telescope. After stowing WFPC1 in the payload bay for return to Earth, Hoffman replaced two magnetometers, essentially compasses the telescope uses to determine its orientation in space. This third spacewalk lasted 6 hours 47 minutes.

Astronaut Kathryn C. Thornton works in shuttle Endeavour’s payload bay European Space Agency astronaut Claude Nicollier controlling the Remote Manipulator System, Thornton, top, removes the Corrective Optics Space telescope Axial Replacement (COSTAR) from its storage location Astronaut Thomas D. Akers, inside the Hubble Space Telescope prepares to install the COSTAR
Fourth spacewalk. Left: Astronaut Kathryn C. Thornton works in shuttle Endeavour’s payload bay. Middle: With European Space Agency astronaut Claude Nicollier controlling the Remote Manipulator System, Thornton, top, removes the Corrective Optics Space telescope Axial Replacement (COSTAR) from its storage location. Right: Astronaut Thomas D. Akers, inside the Hubble Space Telescope prepares to install the COSTAR.

For Akers and Thornton, the primary tasks of the fourth spacewalk on the mission’s seventh day focused on the removal of the HSP instrument and replacing it with the COSTAR system to correct the telescope’s optics. Akers opened the telescope’s shroud doors and with Thornton removed the HSP, temporarily stowing it on the side of the payload bay. Nicollier then maneuvered the RMS with Thornton to pick up COSTAR from its storage location and translate them to Hubble where Akers awaited to help with the installation. After closing the door and stowing the HSP, and installing an electronics package with additional computer memory, Akers and Thornton finished the 6-hour 50-minut spacewalk.

Remote Manipulator System operator European Space Agency astronaut Claude Nicollier translates Jeffrey A. Hoffman and F. Story Musgrave to the top of the Hubble Space Telescope The second of two solar arrays unfurls as Hoffman and Musgrave continue working Hoffman celebrates the first Hannukah in space, with a spinning dreidel floating nearby
Fifth spacewalk. Left: Remote Manipulator System operator European Space Agency astronaut Claude Nicollier translates Jeffrey A. Hoffman and F. Story Musgrave to the top of the Hubble Space Telescope. Middle: The second of two solar arrays unfurls as Hoffman and Musgrave continue working. Right: Hoffman celebrates the first Hannukah in space, with a spinning dreidel floating nearby.

On the morning of the eighth day, Bowersox used Endeavour’s thrusters to slightly raise and circularize Hubble’s orbit. Hoffman and Musgrave stepped outside for the mission’s fifth and final spacewalk. When the two newly installed solar arrays failed to deploy after ground commanding, they manually deployed them, and the arrays unfurled without incident. They next replaced the solar array drive electronics and fitted an electronic connection box on the GHRS instrument. Hoffman and Musgrave’s final task involved installing covers, manufactured by Bowersox and Nicollier on board the shuttle, on the telescope’s magnetometers. The final spacewalk lasted 7 hours 21 minutes, bringing the mission’s total spacewalk time to 35 hours 28 minutes. Once back inside Endeavour, Hoffman celebrated the first Hanukkah in space during a televised broadcast, displaying a traveling menorah, unlit of course, and a spinning dreidel.

European Space Agency astronaut Claude Nicollier grapples the Hubble Space Telescope, with its high-gain antenna deployed, just prior to release Hubble slowly drifts away from Endeavour A distant view of Hubble, right, with a crescent Moon
Left: European Space Agency astronaut Claude Nicollier grapples the Hubble Space Telescope, with its high-gain antenna deployed, just prior to release. Middle: After its release, Hubble slowly drifts away from Endeavour. Right: A distant view of Hubble, right, with a crescent Moon.

On flight day nine, Nicollier grappled Hubble with the RMS for the final time and lifted it above the payload bay. Ground controllers commanded its aperture door to open, and Nicollier released the telescope. Bowersox fired Endeavour’s thrusters to slowly back away from the telescope. The next day, the astronauts enjoyed a well-deserved day of rest. They returned the shuttle’s cabin pressure to 14.7 psi and tidied up the spacecraft. On the mission’s 11th day, Covey and Bowersox tested Endeavour’s flight control surfaces and practiced touchdowns using a laptop computer, all in preparation for deorbit, entry, and landing the following day.

Astronaut Richard O. Covey guides Endeavour to a landing at NASA’s Kennedy Space Center (KSC) in Florida Workers at KSC continue to safe Endeavour following its landing Images of M100 galactic nucleus before, left, and after the first servicing mission showing the improved optical qualities
Left: Astronaut Richard O. Covey guides Endeavour to a landing at NASA’s Kennedy Space Center (KSC) in Florida. Middle: Workers at KSC continue to safe Endeavour following its landing. Right: Images of M100 galactic nucleus before, left, and after the first servicing mission showing the improved optical qualities.

On Dec. 13, 1993, their 12th and final day in space, the astronauts donned their pressure suits and prepared for the return to Earth. Due to predicted worsening weather conditions at KSC, Mission Control elected to bring them home one orbit earlier than planned. Covey guided Endeavour to a smooth landing at night at KSC, concluding a flight of 10 days, 19 hours, 59 minutes. They circled the Earth 163 times. Within a month, new images from Hubble indicated the repairs returned the telescope to its expected capabilities, providing astronomers with a unique observation platform. The lessons learned from planning and executing the complex series of spacewalks, with extensive coordination with teams on the ground, proved highly useful not only for future Hubble servicing mission but also for the difficult spacewalks required to assemble and maintain the International Space Station.

Timeline of the Hubble Space Telescope’s instruments and their replacements during servicing missions Hubble as it appeared after its release during the final servicing mission in 2009
Left: Timeline of the Hubble Space Telescope’s instruments and their replacements during servicing missions. Right: Hubble as it appeared after its release during the final servicing mission in 2009.

Although the STS-61 crew’s work left the Hubble Space Telescope in better condition than originally designed, over the years it required additional servicing to ensure it met its expected 15-year on-orbit life. Four additional shuttle crews serviced the telescope between 1997 and 2009, and today it carries a suite of instruments far more advanced than its original complement. During the five servicing missions, 16 space walking astronauts conducted 23 spacewalks totaling more than 165 hours, or just under 7 days, to make repairs or improvements to the telescope’s capabilities. To summarize the discoveries made by scientists using data from the Hubble Space Telescope is well beyond the scope of this article. Suffice it to say that during its more than 30 years of operation, information and images returned by Hubble continue to revolutionize astronomy, literally causing scientists to rewrite textbooks, and have dramatically altered how the public views the wonders of the universe. On the technical side, the launch of Hubble and the servicing missions to maintain and upgrade its capabilities have proven conclusively the value of maintainability of space-based scientific platforms. 

Watch the STS-61 crew narrate a video of their Hubble servicing mission.

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      Erica Hammerstein, another UC Berkeley postdoctoral researcher, scrutinized the Hubble images as part of the study, but did not find any evidence of a past galaxy merger. But she explained, “There is already good evidence that galaxy mergers enhance TDE rates, but the presence of a second black hole in AT2024tvd’s host galaxy means that at some point in this galaxy’s past, a merger must have happened.”
      Specialized for different kinds of light, observatories like Hubble and Chandra work together to pinpoint and better understand fleeting events like these. Future telescopes that will also be optimized for capturing transient events like this one include the National Science Foundation’s Vera C. Rubin Observatory and NASA’s upcoming Nancy Grace Roman Space Telescope. They will provide more opportunities for follow-up Hubble observations to zero in on a transient’s exact location.
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      Hubble’s Universe Uncovered: Black Holes

      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.
      ZTF is a public-private partnership, with equal support from the ZTF Partnership and from the U.S. National Science Foundation.
      Facebook logo @NASAHubble @NASAHubble Instagram logo @NASAHubble Related Images & Videos
      Six panel illustration of Black Hole TDE AT2024tvd
      This is a six-panel illustration of a tidal disruption event around a supermassive back hole.


      Black Hole TDE AT2024tvdu00a0
      This is a Hubble Space Telescope image of a distant galaxy that is host to the telltale signature of a roaming supermassive black hole.


      Black Hole TDE AT2024tvd (Hubble + Chandra)
      This is a combined Hubble Space Telescope/Chandra X-Ray Observatory image of a distant galaxy that is host to the telltale signature of a roaming supermassive black hole.


      Black Hole TDE AT2024tvd Compass Image
      This is a combined Hubble Space Telescope/Chandra X-Ray Observatory image of a distant galaxy that is host to the telltale signature of a roaming supermassive black hole.


      Black Hole Tidal Disruption Event
      This is a video animation of a tidal disruption event (TDE), an intense flash of radiation caused by the supermassive black hole eating a star. The video begins by zooming into a galaxy located 600 million light-years away.




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      Details
      Last Updated May 08, 2025 Editor Andrea Gianopoulos Location NASA Goddard Space Flight Center
      Contact Media Claire Andreoli
      NASA’s Goddard Space Flight Center
      Greenbelt, Maryland
      claire.andreoli@nasa.gov
      Ray Villard
      Space Telescope Science Institute
      Baltimore, Maryland

      Related Terms
      Hubble Space Telescope Astrophysics Astrophysics Division Black Holes Chandra X-Ray Observatory Galaxies Goddard Space Flight Center
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    • NASA
      NASA Stennis Releases First Open-Source Software
      By NASA
      Editor’s Note: The following is one of three related articles about the NASA Data Acquisition System and related efforts. Please visit Stennis News – NASA to access accompanying articles.
      NASA software engineer Brandon Carver updates how the main data acquisition software processes information at NASA’s Stennis Space Center, where he has contributed to the creation of the center’s first-ever open-source software.NASA/Danny Nowlin Syncom Space Services software engineer Shane Cravens, the chief architect behind the first-ever open-source software at NASA’s Stennis Space Center, verifies operation of the site’s data acquisition hardware.NASA/Danny Nowlin NASA’s Stennis Space Center near Bay St. Louis, Mississippi, has released its first-ever open-source software, a peer review tool to facilitate more efficient and collaborative creation of systems applications, such as those used in its frontline government and commercial propulsion test work.
      “Everyone knows NASA Stennis as the nation’s premier rocket propulsion test site,” said David Carver, acting chief of the Office of Test Data and Information Management. “We also are engaged in a range of key technology efforts. This latest open-source tool is an exciting example of that work, and one we anticipate will have a positive and widespread impact.”
      The new NASA Data Acquisition System Peer Review Tool was developed over several years, built on lessons learned as site developers and engineers created software tools for use across the center’s sprawling test complex. It is designed to simplify and amplify the collaborative review process, allowing developers to build better and more effective software applications.
      The new NASA Stennis Peer Review tool was developed using the same software processes that built NDAS. As center engineers and developers created software to monitor and analyze data from rocket propulsion tests, they collaborated with peers to optimize system efficiency. What began as an internal review process ultimately evolved into the open-source code now available to the public.
      “We refined it (the peer review tool) over a period of time, and it has improved our process significantly,” said Brandon Carver (no relation), a NASA Stennis software engineer. “In early efforts, we were doing reviews manually, now our tool handles some of these steps for us. It has allowed us to focus more on reviewing key items in our software.”
      Developers can improve time, efficiency, and address issues earlier when conducting software code reviews. The result is a better, more productive product.
      The NASA Stennis tool is part of the larger NASA Data Acquisition System created at the center to help monitor and collect propulsion test data. It is designed to work with National Instruments LabVIEW, which is widely used by systems engineers and scientists to design applications. LabVIEW is unique in using graphics (visible icon objects) instead of a text-based programming language to create applications. The graphical approach makes it more challenging to compare codes in a review process.
      “You cannot compare your code in the same way you do with a text-based language,” Brandon Carver said. “Our tool offers a process that allows developers to review these LabVIEW-developed programs and to focus more time on reviewing actual code updates.”
      LabVIEW features a comparison tool, but NASA Stennis engineers identified ways they could improve the process, including by automating certain steps. The NASA Stennis tool makes it easier to post comments, pictures, and other elements in an online peer review to make discussions more effective.  
      The result is what NASA Stennis developers hope is a more streamlined, efficient process. “It really optimizes your time and provides everything you need to focus on right in front of you,” Brandon Carver said. “That’s why we wanted to open source this because when we were building the tool, we did not see anything like it, or we did not see anything that had features that we have.”
      “By providing it to the open-source community, they can take our tool, find better ways of handling things, and refine it,” Brandon Carver said. “We want to allow those groups to modify it and become a community around the tool, so it is continuously improved. Ultimately, a peer review is to make stronger software or a stronger product and that is also true for this peer review tool.
      “It is a good feeling to be part of the process and to see something created at the center now out in the larger world across the agency,” Brandon Carver said. “It is pretty exciting to be able to say that you can go get this software we have written and used,” he acknowledged. “NASA engineers have done this. I hope we continue to do it.”
      To access the peer review tool developed at NASA Stennis, visit NASA GitHub.
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      Last Updated May 08, 2025 EditorNASA Stennis CommunicationsContactC. Lacy Thompsoncalvin.l.thompson@nasa.gov / (228) 688-3333LocationStennis Space Center Related Terms
      Stennis Space Center View the full article
    • NASA
      NASA Progresses Toward Crewed Moon Mission with Spacecraft, Rocket Milestones
      By NASA
      Technicians move the Orion spacecraft for NASA’s Artemis II test flight out of the Neil A. Armstrong Operations and Checkout Building to the Multi-Payload Processing Facility at Kennedy Space Center in Florida on Saturday, May 3, 2025. NASA/Kim Shiflett Engineers, technicians, mission planners, and the four astronauts set to fly around the Moon next year on Artemis II, NASA’s first crewed Artemis mission, are rapidly progressing toward launch.

      At the agency’s Kennedy Space Center in Florida, teams are working around the clock to move into integration and final testing of all SLS (Space Launch System) and Orion spacecraft elements. Recently they completed two key milestones – connecting the SLS upper stage with the rest of the assembled rocket and moving Orion from its assembly facility to be fueled for flight.

      “We’re extremely focused on preparing for Artemis II, and the mission is nearly here,” said Lakiesha Hawkins, assistant deputy associate administrator for NASA’s Moon to Mars Program, who also will chair the mission management team during Artemis II. “This crewed test flight, which will send four humans around the Moon, will inform our future missions to the Moon and Mars.”
      Teams with NASA’s Exploration Ground Systems Program begin integrating the interim cryogenic propulsion stage to the SLS (Space Launch System) launch vehicle stage adapter on Wednesday, April 30, 2025, inside the Vehicle Assembly Building at NASA’s Kennedy Space Center in Florida. NASA/Isaac Watson On May 1, technicians successfully attached the interim cryogenic propulsion stage to the SLS rocket elements already poised atop mobile launcher 1, including its twin solid rocket boosters and core stage, inside the spaceport’s Vehicle Assembly Building (VAB). This portion of the rocket produces 24,750 pounds of thrust for Orion after the rest of the rocket has completed its job. Teams soon will move into a series of integrated tests to ensure all the rocket’s elements are communicating with each other and the Launch Control Center as expected. The tests include verifying interfaces and ensuring SLS systems work properly with the ground systems.

      Meanwhile, on May 3, Orion left its metaphorical nest, the Neil Armstrong Operations & Checkout Facility at Kennedy, where it was assembled and underwent initial testing. There the crew module was outfitted with thousands of parts including critical life support systems for flight and integrated with the service module and crew module adapter. Its next stop on the road to the launch pad is the Multi-Payload Processing Facility, where it will be carefully fueled with propellants, high pressure gases, coolant, and other fluids the spacecraft and its crew need to maneuver in space and carry out the mission.

      After fueling is complete, the four astronauts flying on the mission around the Moon and back over the course of approximately 10 days, will board the spacecraft in their Orion Crew Survival System spacesuits to test all the equipment interfaces they will need to operate during the mission. This will mark the first time NASA’s Reid Wiseman, Victor Glover, and Christina Koch, and CSA (Canadian Space Agency) astronaut Jeremy Hansen, will board their actual spacecraft while wearing their spacesuits. After the crewed testing is complete, technicians will move Orion to Kennedy’s Launch Abort System Facility, where the critical escape system will be added. From there, Orion will move to the VAB to be integrated with the fully assembled rocket.

      NASA also announced its second agreement with an international space agency to fly a CubeSat on the mission. The collaborations provide opportunities for other countries to work alongside NASA to integrate and fly technology and experiments as part of the agency’s Artemis campaign.

      While engineers at Kennedy integrate and test hardware with their eyes on final preparations for the mission, teams responsible for launching and flying the mission have been busy preparing for a variety of scenarios they could face.

      The launch team at Kennedy has completed more than 30 simulations across cryogenic propellant loading and terminal countdown scenarios. The crew has been taking part in simulations for mission scenarios, including with teams in mission control. In April, the crew and the flight control team at NASA’s Johnson Space Center in Houston simulated liftoff through a planned manual piloting test together for the first time. The crew also recently conducted long-duration fit checks for their spacesuits and seats, practicing several operations while under various suit pressures.
      NASA astronaut Christina Koch participates in a fit check April 18, 2025, in the spacesuit she will wear during Artemis II. NASA/Josh Valcarcel Teams are heading into a busy summer of mission preparations. While hardware checkouts and integration continue, in coming months the crew, flight controllers, and launch controllers will begin practicing their roles in the mission together as part of integrated simulations. In May, the crew will begin participating pre-launch operations and training for emergency scenarios during launch operations at Kennedy and observe a simulation by the launch control team of the terminal countdown portion of launch. In June, recovery teams will rehearse procedures they would use in the case of a pad or ascent abort off the coast of Florida, with launch and flight control teams supporting. The mission management team, responsible for reviewing mission status and risk assessments for issues that arise and making decisions about them, also will begin practicing their roles in simulations. Later this summer, the Orion stage adapter will arrive at the VAB from NASA’s Marshall Spaceflight Center in Huntsville, Alabama, and stacked on top of the rocket.

      NASA astronauts Reid Wiseman (foreground) and Victor Glover participate in a simulation of their Artemis II entry profile on March 13, 2025.NASA/Bill Stafford Through Artemis, NASA will send astronauts to explore the Moon for scientific discovery, economic benefits, and build the foundation for the first crewed missions to Mars.
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