The Final Mission

The imagination of the human mind is stimulated through images depicting far away galaxies and plumes of colorful gasses - images captured by the now legendary Hubble Space Telescope. In order to create these awe-inspiring photographs, the telescope must be repaired and updated periodically with all of the latest technological advancements.

The seven-member crew of Space Shuttle Atlantis blasted off to service the Hubble for the fifth and final time on May 11, 2009. During the12-day, 21-plus hour journey, the astronauts completed the first-ever on-orbit repair of the Space Telescope Imaging Spectrograph (STIS) and the Advanced Camera for Surveys (ACS), neither of which were designed to be fixed in space.

Prepare For Launch

The astronauts were rigorously trained to repair any problems that may occur to the spacecraft and/or the Hubble.

They intensively practiced specific mission goals to repair the Hubble, malfunction and contingency preparations, flight simulations, and inspections.

"We train for the space walks in a swimming pool," explains STS-125 astronaut Col. Michael Good, mission specialist. "It's not just any swimming pool, though. It's 40' deep, and it's about six million gallons of water." Inside the pool, called the Neutral Buoyancy Lab (NBL), the astronauts perform the tasks they will do in space on a full-scale mock-up of the Hubble while in full space gear. "The suits are pressurized, and we're working underwater. It's very analogous to floating in space," Good continues.

The astronauts also collaborated with Goddard Space Flight Center (GSFC) engineers in designing specialized tools to be used during the space walks. Some of the tools were created specifically for the STS-125 tasks that were not meant to be performed in space, and were designed to complete these tasks in extraordinarily harsh environments by astronauts in large, awkward, bulky suits.

"One of the failed instruments [on the Hubble] has 111 screws that they have to remove. So you can immediately see the challenge - you don't want 111 screws floating around," explains Mike Weiss, deputy program manager - technical, Hubble Space Telescope Program, Goddard Space Flight Center. "So we built a special device called the fastener capture plate that the astronauts install over the top of the instrument panel, and it has access holes for the drill bit." A special mini power tool was also customized for the same job so that the speed and torque needed to remove and replace the screws were available. The tools developed by GSFC go through a trial-and-error period to ensure proper functionality in-flight.

"We start in a laboratory here at Goddard Space Flight Center, and we start with a design concept for either the tool or the crew aide. We then take that as far as we can take it in an engineering development process, and then we go and try it underwater with the astronauts," Weiss says.

The GSFC engineers work hand-in-hand with the astronauts during training and flight preparation to determine if the tools need adjustments. "It's a design iteration process directly between the user and the designer. Every second counts when you're doing a space walk - you can not waste any energy or any time, so everything ends up being highly optimized for the particular task," Weiss adds.

The Mission

At about 350 miles above Earth's surface, Space Shuttle Atlantis rendezvoused with the Hubble Space Telescope, captured it with its robot arm, and placed it in the shuttle's payload bay for servicing. The extravehicular activities (EVAs) took place on flight days four through eight. The refurbished Hubble Telescope now has four new or rejuvenated scientific instruments, new batteries, new gyroscopes, and a new computer.

Upgrades to the Hubble included the addition of Wide Field Camera 3, a panchromatic camera that allows astronomers to observe galaxy evolution, dark matter and dark energy. Mission Specialists Dr. Andrew Feustel and Dr. John Grunsfeld installed the 900 lb Wide Field Camera 3, replaced the Science Instrument Command and Data Handling System, and installed the Soft Capture Mechanism and three latch kits in the first EVA, which lasted seven hours, 20 minutes.

Mission Specialists Dr. Michael Massimino and Good completed EVA #2, including the replacement of all three Rate Sensor Units, each containing two gyroscopes, as well as the replacement of a 460 lb Battery Module Unit.

This space walk lasted seven hours and 56 minutes.

The third EVA was performed by Feustel and Grunsfeld in six hours and 36 minutes, this time to install the Cosmic Origins Spectrograph and repair the Advanced Camera for Surveys.

Massimino and Good completed the fourth EVA on flight day #7, replacing a power supply board in the Space Telescope Imaging Spectrograph (STIS) using specialized tools, including the fastener capture plate. EVA 4 lasted eight hours and two minutes, due to the difficulty of the task.

Feustel and Grusfeld completed the fifth and final space walk, replacing another of Hubble's 460 lb Battery Module Units, and removing and replacing Fine Guidance Sensor 2. They also installed New Outer Blanket Layers on the exterior of three bays during this seven-hour-and-two-minute-long EVA.

Back to Earth

STS-125 was a complete success, with all objectives met and the crew returning safely at 11:39 a.m. EDT on May 24, 2009 at Edwards Air Force Base, CA. Atlantis and the crew had traveled 197 Earth Orbits for a total distance of 5,276,000 miles, watching the sun rise and set every 90 minutes.

The crew had unexpected extra time in space due to the weather in Florida delaying - and eventually relocating - the shuttle's landing, giving them some time to relax and enjoy the scenery. "You can actually see the telescope from Earth on a clear night," Good says. "I've stood out in my driveway before at night and watched it go overhead and just thought about myself going up there and holding on to it as it is going across the sky.

You're kind of like a satellite out there." Now that the mission is complete, the Hubble is prepared to assist the scientific community for at least five more years, and likely longer. Human hands have touched the telescope for the final time, and so far, the upgrades and repairs have been tested and have proven to be a success.

"Hubble has always been a pathfinder, not only for its own scientific return, but for the U.S. space program," Weiss reflects. "It was a pathfinder on how to conceive, train for and execute large numbers of EVAs back to back. We developed certain things that we did for the Hubble, and those carried over to the space station, and that's how the agency does business today."