Ten years have now passed since STS-117 literally changed the face of the International Space Station (ISS), delivering and activating a new set of power-producing solar arrays, batteries and radiators. Aboard shuttle Atlantis in June 2007 for what would turn out to be the longest mission of her career, six NASA astronauts installed the gigantic S-3/S-4 component of the station’s Integrated Truss Structure (ITS) and performed no fewer than four sessions of Extravehicular Activity (EVA). On STS-117, an element of symmetry was afforded to the appearance of the ISS, as well as providing it with the electricity-generating capability to support the arrival of European and Japanese labs in 2008.
At the time of the Columbia disaster on 1 February 2003, an earlier incarnation of the STS-117 crew was already in training. In August 2002, NASA named Commander Rick “C.J.” Sturckow, Pilot Mark Polansky and Mission Specialists Pat Forrester, Joan Higginbotham, Jim “J.R.” Reilly and Rick Mastracchio to the flight, with an expectation that they would launch in the fall of the following year. Between them, they had six previous missions to the ISS—more than any other crew at that time—and Sturckow would become the first person to fly to the multi-national station on as many as three occasions.
In the aftermath of STS-107, all assigned astronauts were indefinitely stood down, but in February 2005 NASA began to reassemble crews as the effort to return the shuttle fleet to operational service entered high gear. Sturckow, Forrester, Reilly and Mastracchio remained attached to the “new” STS-117, with Polansky and Higginbotham having been moved onto another mission. Joining the crew in their stead were Lee “Bru” Archambault as Pilot and John “Danny” Olivas as the fourth Mission Specialist. Initially targeted to fly early in 2006, ongoing shuttle delays saw STS-117 slip into the spring of 2007. As the astronauts trained, more crew changes were afoot. In May 2006, Mastracchio was moved onto another flight and was replaced on STS-117 by Steve Swanson.
Just Do It…Again formed the overarching theme for STS-117, since it would install the S-3/S-4 starboard-side segment of the station’s Integrated Truss Structure (ITS), providing a near-mirror image of the port-side P-3/P-4 segment set in place in September 2006 by Atlantis’ STS-115 crew. Weighing 35,600 pounds (16,150 kg), the S-3/S-4 hardware would provide a quarter of the station’s electrical capability, via the twin Solar Array Wings (SAWs) of Power Channels 1A and 3A. Its hexagon-shaped S-3 component was connected to the 10-foot-wide (3.3-meter) Solar Alpha Rotary Joint (SARJ), which rotated the arrays to continuously track the Sun. Finally, its S-4 element held the photovoltaic radiators and batteries, together with the Solar Array Blanket Boxes (SABBs), which would deploy the SAWs in opposite directions to a total length of almost 240 feet (73 meters). On the ground, the S-3/S-4 launch package measured about 45 feet (13 meters) long, allowing it to fit snugly into the shuttle’s payload bay.
However, when STS-115 installed the P-3/P-4 segment, its crew uncovered a number of significant obstacles. “During that mission, difficulties were encountered with software associated with the gears within the joint and spacewalking astronauts had trouble loosening bolts during its structural preparation,” NASA noted in its STS-117 press kit. “Software to control the SARJ was updated and the spacewalkers now will carry another tool, called a torque multiplier, to help remove any balky launch restraints.”
“If we do encounter the same difficulty with high torques that they had, we’ll break out this tool,” Sturckow told an interviewer, before the flight, “and we’ll apply whatever torque it takes to break the bolt or back it out at the higher torque settings.”
By the fall of 2006, STS-117 found itself scheduled for launch in mid-March of the following year. However, on 26 February, with the shuttle already on the launch pad, the Kennedy Space Center (KSC) in Florida suffered a severe hail storm. Several thousand points of damage were incurred on the upper portion of the External Tank (ET)—as well as minor surface impacts to 26 heat-resistant tiles on Atlantis’ port-side wing—and NASA ordered the STS-117 stack to be rolled back to the Vehicle Assembly Building (VAB) on 4 March for inspections and repairs.
Teams from KSC, United Space Alliance and Lockheed Martin, as well as the Johnson Space Center (JSC) in Houston, Texas, the Marshall Space Flight Center (MSFC) in Huntsville, Ala., and NASA Headquarters in Washington, D.C., toiled to repair the ET over the next two months. This involved the erection of scaffolding and platforms around the tank. The density of damage was so high that in places it was necessary to remove a half-inch-thick (1.2 cm) layer of insulating foam in the entire area to eliminate all damage and avoid making numerous individual repairs. At length, on 15 May, Atlantis returned to the pad, tracking an opening launch attempt on 8 June.
But the long delay had opened up other problems. Had STS-117 flown as intended in March 2007, it would have been followed by STS-118 in June, one of whose tasks was to bring home NASA’s Suni Williams after her six-month ISS increment and replace her with fellow U.S. astronaut Clay Anderson. With STS-117 now rescheduled for June, and STS-118 pushed back into August, there existed the very real probability that Williams’ stay aboard the station would push her beyond a half-year and challenge NASA’s “safe” limits of radiation exposure for astronauts.
STS-117 was not planned as a crew-rotation mission, partly because of the large payload demand of the S-3/S-4 cargo, but in April 2007 NASA announced that Anderson would join its crew, thereby allowing Williams to return to Earth in approximately the same timeframe as she would have done on the original STS-118. It was considered prudent, the agency noted, to return Williams and deliver Anderson, sooner rather than later. “I had an inkling that it was coming,” Anderson acquiesced in a pre-flight interview. He jokingly told Williams that he was her knight in shining armor; coming up to the ISS “to rescue her from her throes of her potential nine-month duration on-orbit”.
Humor aside, Anderson’s role provided the crew with an extra pair of hands during the mission. “I hope to be their utility infielder,” he said. “I hope to help Commander Sturckow anywhere he needs me to help. He will have some specific tasks timelined for me that I will be trained specifically to do and then I can help the guys. I can take care of getting them some food if they’re in a tough part of the timeline, I can help throw a few switches if they need me to do that. I will be there to help the crew.”
The seven astronauts arrived at KSC on 4 June, tracking an opening launch attempt on the evening of the 8th. Countdown operations proceeded normally, in spite of a 30-percent probability that thunderstorms and associated anvil clouds might interfere with Atlantis’ chances of flying on time. However, by the evening before launch, weather conditions had improved to 80-percent favorable and Sturckow and his crew roared away from Pad 39A, right on the opening of 8 June’s “window” at 7:38 p.m. EDT. It was the first launch from this storied launch pad—whose heritage dated back more than four decades to the Apollo era—since the final ascent of Columbia in early 2003.
“To assemble the framework for the science laboratories of tomorrow,” exulted NASA’s veteran launch announcer George Diller, as Atlantis cleared the tower and headed into the steadily darkening Florida sky. He was right. With the electrical power capability afforded by the S-3/S-4 truss segment, the road was clear for the launch of Europe’s Columbus and Japan’s Kibo research labs, then planned for 2008. At the time of launch, the ISS itself was orbiting high above the southern Indian Ocean, southwest of Australia, and the incumbent Expedition 15 crew of Commander Fyodor Yurchikhin and Flight Engineers Oleg Kotov and Suni Williams were able to watch via a video link from Mission Control.
With Sturckow, Archambault and Swanson in charge of the flight deck for STS-117, the first two days of the mission were spent executing a series of rendezvous “burns” to steadily close the distance and align their orbital parameters with the space station. Elsewhere, Reilly, Olivas and Anderson checked out the four Extravehicular Mobility Units (EMUs) which would be worn during the three planned spacewalks. The crew also extended the ring on the Orbiter Docking System (ODS) in the payload bay and activated the tools needed for the critical rendezvous phase.
As was customary in the aftermath of the Columbia disaster, a several-hours-long effort to meticulously inspect the shuttle’s Thermal Protection System (TPS) was performed with the Orbiter Boom Sensor System (OBSS). Mounted at the end of the Remote Manipulator System (RMS) mechanical arm, the OBSS utilized laser and other sensors and was targeted specifically at a region of insulating blanket on Atlantis’ port-side Orbital Maneuvering System (OMS) pod. Initial inspections immediately after launch suggested that a small section of blanket, measuring 4 inches (10 cm) by 6 inches (15 cm), had become detached and raised from adjoining thermal tiles.
Additional imagery acquired by Olivas from Atlantis’ flight deck windows added to a growing folio of data for ground-based experts to analyze. Four days into the flight, the Mission Management Team (MMT) elected to extend STS-117 by 48 hours in order to accommodate an additional EVA to repair the blanket. Detailed plans for this task were completed and tested on the ground.
In the meantime, by mid-morning on 10 June, Sturckow had executed a smooth Terminal Initiation (TI) burn to position the shuttle on-course to close the final nine miles (15 km) towards its quarry. By early afternoon, that distance had closed to around 600 feet (180 meters), allowing Sturckow to perform the Rendezvous Pitch Maneuver (RPM), “backflipping” Atlantis in order that Williams—located at the windows of the U.S. Destiny lab and handling long-range, high-resolution cameras—could extensively photograph the underside of the approaching shuttle. He then completed a flawless final approach and docked smoothly at Pressurized Mating Adapter (PMA)-2, on the forward end of Destiny, at 3:36 p.m. EDT.
Ahead lay a mission which would turn out to be the longest in Atlantis’ career, would involve an additional—and unexpected—spacewalking task and whose time on-orbit would be backdropped by problems on the station’s Russian Orbital Segment (ROS). Yet by the time STS-117 returned to Earth, the ISS would be ready to receive its next set of pressurized modules and primed for its role as a fully-functional research lab in space.
The second part of this article will appear tomorrow.