Fifteen years have now passed since Shuttle Discovery dropped off and picked up crew members at the International Space Station (ISS) and supported a pair of Extravehicular Activities (EVAs) to transition the multi-national outpost toward a state of full utilization. By August 2001, the U.S. “core” of the station—its Destiny lab, its Unity node, its Canadarm2 robotic arm, its Quest airlock, and its first gigantic set of power-producing solar arrays—were in place, thereby wrapping up “Phase II” of the ISS Program and enabling the science-focused Phase III to begin. With the arrival of Expedition 3 Commander Frank Culbertson of NASA and his Russian flights engineers Vladimir Dezhurov and Mikhail Tyurin, science was to take center-stage, with the arrival of key research facilities aboard STS-105.
As outlined in yesterday’s AmericaSpace history article, STS-105 was designated “Assembly Mission 7A.1,” one of several dot flights, added to the ISS construction manifest to accommodate late plans and changes. After launching successfully on 10 August 2001, Commander Scott “Doc” Horowitz, Pilot Rick “C.J.” Sturckow, and Mission Specialists Pat Forrester and Dan Barry oversaw two days of rendezvous and phasing maneuvers, which produced a successful docking about 46 hours into the flight. This was followed by pressurization and leak checks and the hatches were opened between Discovery and the space station. The outgoing Expedition 2 crew—Commander Yuri Usachev of Russia and NASA flight engineers Jim Voss and Susan Helms—were on hand to welcome the new arrivals aboard their orbital home.
“Hey, how you doing?” called Horowitz. “You ready for visitors?”
“Good to see you,” replied Usachev.
After the bear-hugs and handshakes, one of the first joint tasks centered upon the Soyuz TM-32 spacecraft, where the outgoing and incoming expedition crews swapped out the seat liners of Usachev, Voss, and Helms and exchanged them with the seat liners of Dezhurov, Tyurin, and Culbertson. Leak checks were also performed on their Russian-made Sokol (“Falcon”) space suits. This was to ensure the Soyuz and the suits could support a crew-return capability in the event of an emergency. In completing this step, Expedition 3 officially took control of the ISS, although it would be a few more days before a ceremonial handover of command would occur.
Although this was the second time that ISS crews had been changed via shuttle—following on the heels of the Expedition 1/2 swap on STS-102 in March 2001—Horowitz noted in his pre-flight interview that there were some differences. “One of the lessons we learned about crew exchange is you’d like to try to keep the crew exchange all at the same time, if you can,” he said. “They [STS-102] had some other operational reasons they could not, because of the complexity of their mission and the different tasks that had to be done by different crew members on both sides. We’ve taken those lessons learned and tried to simplify their plan to make our exchange go smoother. One of the ways of doing that is to have the exchange all happen on one day, so that, if you have to do operations on either side of a closed hatch, you have the correct crew members on each side.”
On the morning of 13 August, Forrester deftly unberthed the Leonardo Multi-Purpose Logistics Module (MPLM) from Discovery’s payload bay, using the RMS. Aboard the ISS, the Expedition 2 crew activated the latching mechanisms at the Earth-facing (or “nadir”) Common Berthing Mechanism (CBM) of the Unity node. Forrester “flew” the 9,000-pound (4,000-kg) Leonardo into position and, after receiving a Ready-to-Latch (RTL) indicator, it was attached to the station and a half-dozen fluid, power, and data connectors were connected. One of three MPLMs, Leonardo was making its second flight, having previously journeyed to the ISS in March 2001, and was securely in place at Unity nadir by 11:55 a.m. Over the next few hours, the RMS was detached from the module and the crews and Mission Control set to work pressurizing the vestibule between the Unity nadir CBM and Leonardo, ahead of hatch opening at 3:47 p.m.
Efforts then entered high gear to unload more than 7,000 pounds (3,200 kg) of equipment, food, clothing, and supplies. “Where the rubber meets the road” was the description offered by Dan Barry, who was responsible for the transfer to the station, as well as the loading of around 3,000 pounds (1,360 kg) of unneeded gear to bring back to Earth. Heading uphill were two new Expedite the Processing of Experiments for Space Station (EXPRESS) research racks—the 1,175-pound (533-kg) EXPRESS Rack-4 and the 1,199-pound (544-kg) EXPRESS Rack 5—for the Destiny lab. In organising the transfer, Barry picked up some advice from ISS “old hand” Voss, who suggested transferring everything over to the station, ensuring it was on “the right side of the hatch,” before unpacking it. This prompted some praise from Yuri Usachev, who remarked that it was the fastest MPLM unloading he had seen. However, he cautioned: “Dan, it’s easier to destroy than it is to create!”
As unloading operations progressed, Discovery herself conducted 240 thruster “burns” over the course of an hour on 14 August to slightly nudge the station’s orbit a little higher. A second re-boost, which included 253 thruster firings, was performed on the 17th.
With their first EVA planned for the 16th, Barry and Forrester worked with Sturckow to checkout their suits and tools. The first spacewalk was tasked with installing the 1,000-pound (450-kg) Early Ammonia Servicer (EAS) onto the station’s P-6 truss structure. The latter was designed to provide a spare ammonia supply for the early cooling system, should the need arise. “There are two completely separate coolant loops which are redundant, for the most part,” said Barry, “but if there were to be a leak and it were to be severe enough to lose a significant amount of coolant, this device allows us to replenish that coolant.”
Although the Quest airlock had been attached to the station and activated a few weeks earlier, neither EVA on STS-105 would use it. As a result, the hatches between Discovery and the rest of the station were closed on the afternoon of 15 August, in order that the pressure in the shuttle’s cabin could be lowered from 14.7 psi to 10.2 psi to accommodate “pre-breathing” requirements. Next morning, at 9:58 a.m. EDT, on the 1,000th day since the first ISS hardware had launched to orbit in November 1998, Barry and Forrester headed out of the shuttle’s airlock. Theirs was the 25th spacewalk devoted to ISS assembly and maintenance in just 32 months.
With only four “dedicated” crew members on the shuttle side, STS-105 saw Horowitz assume control of the RMS during the EVA. His first task was to grapple the EAS, whereupon Barry—designated “EV1,” the lead spacewalker, with red stripes on the legs of his suit for identification—proceeded to tether himself to the mechanical arm. He was followed in short order by Forrester (“EV2,” wearing a pure white suit) and the duo set to work removing six bolts to release the EAS from its Integrated Cargo Carrier (ICC) in Discovery’s payload bay. When the payload was released, Horowitz gave it and the spacewalkers a ride on the RMS up to the P-6 truss. Upon reaching their destination, Barry set up an Articulating Portable Foot Restraint (APFR).
Since the limited reach of the 50-foot-long (15-meter) mechanical arm meant that it could not directly install the EAS, Horowitz instead released it into Barry’s gloved hands. The sheer size of the EAS required Forrester to issue verbal directions on how to maneuver it into position. Next, the duo set to work tightening a bolt to hold the EAS in place and hooking up and securing a pair of cables for “keep-alive” electrical heaters. Completion of the EAS installation task put Barry and Forrester two-thirds of the way through their mandated tasks for EVA-1.
As Horowitz handled RMS duties, Sturckow was the Intravehicular (IV) crew member, talking Barry and Forrester through each step and task and liaising with the Mission Control Center (MCC) to handle unforeseen problems and get-ahead tasks. In addition to installing the EAS, the duo also mounted the first pair of suitcase-sized Materials International Space Station Experiment (MISSE-1 and 2) packages onto handrails on the exterior of the Quest airlock, exposing hundreds of samples—including solar cell materials, optical coatings, and various composites—to the harsh atomic oxygen of low-Earth orbit. MISSE-1 and 2 were scheduled to be retrieved during shuttle mission STS-114 in March 2003, but the loss of Columbia postponed their returned to Earth for several years. Not until August 2005 did they finally reach terra firma.
Also on 17 August, following several days of “hand-over” briefings, Expedition 3 Commander Frank Culbertson ceremonially took control of the space station from his outgoing Expedition 2 counterpart, Yuri Usachev.
Barry and Forrester’s second and final EVA got underway at 9:42 a.m. EDT on the 18th. They installed a pair of 45-foot-long (14-meter) heater cables along the port and starboard sides of the Destiny lab, setting the stage for the arrival of the S-0 hardware—the central component of the massive Integrated Truss Structure (ITS)—on Assembly Mission 8A in early 2002. Known as Launch-to-Activation (LTA) Cables, they were several inches thick and would provide backup power capability for the truss, if necessary. The S-0 hardware had to be deployed in a very short period of time and the risk of leaving its avionics boxes unpowered for too long carried the risk of damage. “Should 8A run into trouble during their spacewalk and be unable to get the truss completely installed, these cables provide an emergency source of power,” Barry explained. “So they’re really there just in case things don’t go as planned during 8A’s spacewalks.”
“In order to tie those cables down, they have to be tied to handrails,” added Horowitz, “and the handrails are not installed on the lab.” When Destiny rose into orbit on Assembly Mission 5A in February 2001, clearances between the gigantic lab and the envelope of the shuttle’s payload bay were so tight that it was not possible to install the handrails before launch. The only option was to install then on-orbit. This required Barry and Forrester to haul four bags—two laden with the LTA cables and two others with 11 handrails—out of Discovery’s airlock and to the worksite. Once then, one man set himself up on the port side of Destiny and the other took up position on the starboard side, then unreeled the LTA cables like a pair of fire hoses and anchored them to the handrails. They hooked the cables to power receptacles on the lab. Altogether, the astronauts spent five hours and 29 minutes in vacuum. Upon their return to Discovery’s airlock, Barry had accrued more than 25 hours of spacewalking time, across four excursions, with Forrester wrapping up the first pair of EVAs of his career.
It was turning into a busy first mission for Forrester. Next morning, backed up by Horowitz, he was at the controls of the RMS to detach Leonardo from the Unity nadir port and return it to Discovery’s payload bay at 3:15 p.m. Between June 2002 and its final installation onto the ISS as the Permanent Multipurpose Module (PMM) in March 2011, Leonardo would fly a further six shuttle missions.
Bidding farewell to Culbertson, Dezhurov, and Tyurin, the STS-105 astronauts and departing Expedition 2 crew headed over to Discovery in the opening hours of 20 August, with hatch closure at 8 a.m. Undocking occurred at 10:52 a.m. and Sturckow took manual control, performing a strategic fly-around of the space station at a distance of 450 feet (140 meters), before withdrawing. It would not be his final flight to the ISS. In fact, at the time of writing, Sturckow is one of only four U.S. astronauts—joining Rick Mastracchio and the Kelly twins—to have visited the station as many as four times. The flyaround was not only a shuttle tradition, but was a fundamental necessity for upcoming crews, particularly through its photography component. “These photographs are very important for not only general publicity purposes, but we’ve actually used similar photographs,” Sturckow said. “During our training, we’ll pull out fly-around photos and see the exact configuration of different cables, for example.”
Late in the mission, the STS-105 crew deployed the SimpleSat payload, designed to demonstrate inexpensive and commercially available hardware, including Global Positioning System (GPS) attitude control and pointing, in low-Earth orbit. The small satellite was ejected from a Getaway Special (GAS) canister at the rear end of Discovery’s payload bay.
With landing at the Kennedy Space Center (KSC) Shuttle Landing Facility (SLF) planned for 22 August, the day prior was spent configuring the shuttle’s systems and setting up incumbent seats in the middeck for Usachev, Voss, and Helms. These seats would help the trio, as they ended more than five months in weightlessness, to better withstand the forces of re-entry and a return to terrestrial gravity. “The reclined position,” NASA noted, “has been proven to the most comfortable method of return to Earth from space by long-duration crew members.”
Landing conditions in Florida were predicted to be excellent, obliging the Mission Management Team (MMT) to opt against activating the backup site at Edwards Air Force Base, Calif. The crew was awakened at 4:10 a.m. EDT on the 22nd and began stepping smartly through plans for a deorbit burn of the shuttle’s Orbital Maneuvering System (OMS) engines at 11:37 a.m. This would produce the proper conditions to descend across southern Mexico, cross the Bay of Campeche, skirt the northwestern tip of the Yucatan peninsula, and head over the Gulf of Mexico, before entering Florida airspace and touching down at 12:46 p.m. Unfortunately, a rain shower popped up at the end of the SLF, leading to a one-orbit wave-off. Next time around, luck was on the crew’s side. Horowitz and Sturckow executed the deorbit burn at 1:17 p.m. and Discovery alighted smoothly on the KSC runway at 2:23 p.m., wrapping up a spectacular 12-day mission.
This is part of a series of history articles, which will appear each weekend, barring any major news stories. Next week’s article will focus on the 10th anniversary of STS-115, which re-started construction of the International Space Station (ISS) in the aftermath of the Columbia tragedy.
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