Hubble Servicing Mission 4 Shuttle Astronauts Installed Two New

Hubble Servicing Mission 4 A new day dawns for Hubble Shuttle astronauts installed two new instruments, fixed two older ones, and upgraded the space telescope’s gyroscopes and batteries. by Richard Talcott

n the afternoon of May 11, To compound the troubles, three of space shuttle Atlantis roared Hubble’s six gyroscopes had failed, and off Launch Pad 39A at Florida’s two of three Fine Guidance Sensors Kennedy Space Center. At the were ailing. The telescope needs at least time, the Hubble Space Tele- two gyros and two sensors to point O scope was passing overhead. Yet it accurately, so it was facing a possible would take Atlantis 2 days to catch crisis in the not-too-distant future. up with the orbiting observatory To top it off, the telescope’s main and get down to the important work Science Instrument Command and Repairing the Space Tele- of Servicing Mission 4. The goal: Data Handling unit failed September scope Imaging Spectrograph upgrade Hubble by installing new 27, 2008. This unit provides all the (STIS) occupied nearly all of instruments, repairing old ones, and electronics needed to operate the sci- the fourth spacewalk, in part replacing worn-out parts. The result: ence instruments from the ground because of a balky handrail. a resounding success. and send science and engineering Here, Michael Good (on the shuttle’s robotic arm) and After 19 years in the harsh environ- data from Hubble back to Earth. Michael Massimino (just to ment of low Earth orbit, Hubble was The craft has two such units — his right) work on STIS inside showing its age. Two of its four science one active and an unpowered backup. Hubble. All images by NASA instruments — the Space Telescope Although NASA had switched to the Imaging Spectrograph (STIS) and the backup, it did not want to leave the Wide Field Camera 3 finds Advanced Camera for Surveys (ACS) orbiting observatory without a spare. its new home inside Hubble, — had suffered devastating power The space agency had postponed the as astronauts John Grunsfeld failures. STIS no longer worked. And servicing mission from its scheduled (left) and Andrew Feustel wrap ACS, which still operated on one of October 2008 launch until engineers up the camera’s installation Rocketing into space from Cape its three channels, had lost its ability could test and deliver a backup system during the first spacewalk. Canaveral May 11, space shuttle Atlan- to take beautiful images. to Kennedy Space Center. tis and its seven astronauts set off to repair the Hubble Space Telescope.

© 2015 Kalmbach Publishing Co. This material may not be reproduced in any www.Astronomy.com 37 form without permission from the publisher. www.Astronomy.com Hubble drifts away after Atlantis’ crew finished servic- ing it. The space telescope should be set for at least 5 more years of discoveries.

Atlantis crew members pose the day after they released Hubble. Sitting in the front row (left to right) are Gregory Johnson, Scott Altman, and Megan McArthur. Behind them (left to right) are Michael Good, Michael Massimino, John Grunsfeld, and Andrew Feustel.

view a galaxy and see its hot young stars expect that the results will give them a boxes called Rate Sensor Units. Atlantis (which radiate mostly in the ultraviolet) keener insight into the universe’s struc- brought along three replacement units, and cool old stars (which glow in the ture and evolution. but one refused to fit into its slot. The red and near-infrared) at the same time. The third spacewalk also saw astro- astronauts managed to place a spare With its heightened sensitivity and wide nauts install new electronics in the ACS. unit into the slot, so the telescope now field of view, WFC3 will far outclass any The electronics worked, but they restored has six working gyros. of Hubble’s previous cameras. only the camera’s wide-field channel. The other key upgrades went well. Hubble stands tall in the cargo bay of Atlantis. The crew captured this The fifth spacewalk included several maintenance tasks. In this scene, scene after Mission Specialist Megan McArthur grabbed the ­telescope John Grunsfeld (left) and Andrew Feustel prepare to install new thermal During its lifetime, WFPC2 took a few The high-resolution channel remains Hubble now sports a new Science Instru- with the shuttle’s robotic arm. blankets on the space telescope. hundred thousand images of the cosmos. inoperable. Fortunately, scientists use the ment Command and Data Handling unit, Among them were some of Hubble’s most wide-field channel more than any other. a new Fine Guidance Sensor, two new iconic, including the “pillars of creation” Since astronauts installed ACS in 2002, batteries, and three new thermal blankets. in the Eagle Nebula and the Hubble Deep the wide-field channel garnered 70 per- The astronauts also attached the Soft Rendezvous with destiny locked it down. This would be Hubble’s than 15 years on Hubble, however, Field. Atlantis brought the camera back cent of the observation time. Capture Mechanism to Hubble’s back Science operations aboard Hubble home for the next 6 days. WFPC2 didn’t want to leave. to Earth, where it will go on permanent The most complex repair took place end. This allows a next-generation vehi- ­continued until launch. At that point, During five spacewalks lasting a total The astronauts had a difficult time display in the Smithsonian Institution’s on the fourth spacewalk when Massi­ cle to capture the spacecraft and send it mission controllers at NASA’s Goddard of 36 hours and 56 minutes, two teams removing a bolt that held the camera in National Air and Space Museum in mino and Good fixed STIS. NASA did on a controlled reentry into Earth’s atmos­ Space Flight Center in Greenbelt, Mary- of mission specialists repaired the ailing place. They tried a variety of tools and Washington, D.C. not design the spectrograph for repair. phere. But this fate lies at least 5 years in land, began to shut the telescope down. craft. John Grunsfeld and Andrew Feus- even applied extra force to the bolt, all Astronauts installed Hubble’s other The task required the astronauts to pains- the future. No one was thinking about They put its science instruments into tel worked days 1, 3, and 5, while Michael to no avail. If the bolt had broken, they new science instrument — the Cosmic takingly remove 111 screws after affixing that day when McArthur released Hubble standby mode, closed the aperture Massimino and Michael Good donned wouldn’t have been able to remove the Origins Spectrograph (COS) — on the a “capture plate” over the instrument’s back into space May 19. door, and retracted the two large high- their spacesuits on days 2 and 4. The old camera and install the new one. The third spacewalk. It replaces the Cor­ access panel to prevent any screws from Atlantis touched down at Edwards Air gain-antenna masts. teams accomplished all of NASA’s goals pair eventually retrieved a ratchet tool, rective Optics Space Telescope Axial floating free. Oddly enough, this part of Force Base in California May 24, 2 days This was the Hubble that awaited for the mission. But — as always seems to reconfigured it, and managed to remove Replacement — the “glasses” installed the repair went smoothly, but the astro- later and a continent away from its sched- Atlantis and its astronauts as they happen when working in space — there the bolt. The rest of the removal and during the first servicing mission to nauts had trouble removing a handrail to uled landing. Persistent tropical rains in approached May 13. Commander Scott were a few glitches. WFC3’s installation went perfectly. ­compensate for the telescope’s misshapen attach the capture plate. In the end, Massi­ Florida had kept the shuttle in space Altman and Pilot Gregory Johnson One problem came during the first primary mirror. mino simply yanked the handrail off. overtime. Still, NASA couldn’t be happier. brought Atlantis up next to the telescope. spacewalk and threatened the installation New views of the heavens COS breaks down incoming light Atlantis’ 5.3-million-mile (8.5 million Mission Specialist Megan McArthur then of what will become Hubble’s primary Hubble scientists have high hopes for into its component colors, revealing an Ready for the long haul kilometers) journey accomplished all of grappled Hubble with the shuttle’s robotic camera. To install the Wide Field Camera the new camera. WFC3 will observe the object’s temperature, composition, den- The astronauts encountered only one the tasks NASA set out to achieve. And arm, brought it into the payload bay, and 3 (WFC3), Grunsfeld and Feustel first universe at ultraviolet, visible, and near- sity, and velocity. Astronomers will use other significant problem during the Hubble is now back in the peak of health, had to remove the Wide Field and Plan- infrared wavelengths simultaneously. COS’ ultraviolet sensitivity to explore repairs, while replacing the gyroscopes. ready to push the frontiers of astronomi- Richard Talcott is a senior editor of Astronomy. etary Camera 2 (WFPC2). After more With this capability, the camera can distant galaxies and quasars. Researchers The gyros are packed in pairs inside cal observation even deeper.

38 Astronomy • September 09 www.Astronomy.com 39