by Jay Chladek
Discovery arrived at the ISS two days after launch and performed the first rendezvous pitch maneuver of the program. The photographs shot by Krikalev and Phillips during the backflip were breathtaking and proved to be quite a highlight for space enthusiasts and the general public. After docking and hatch opening, the combined crews got to work, performing the ISS resupply tasks with the Raffaello MPLM, including delivery of fresh water supplied by the shuttle’s fuel cells. Robinson and Noguchi got to work on their repair technique tests during their first two EVAs, while NASA analyzed the photographs of Discovery’s bottom. On the second space walk, the pair replaced a failed control gyro on the station.
A couple of days after analyzing the photographs, NASA announced that the third space walk would include an attempt by Robinson to remove a pair of protruding gap fillers from Discovery’s tiles on the underside of the shuttle’s nose. Gap filler is a thin, stiff felt material that is fitted between the shuttle’s tiles. Each tile has a small gap between them to account for thermal expansion and contraction as the shuttle’s aluminum structure heats and cools. The fillers keep the tiles from touching one another and chafing their edges. Two of these pieces of gap filler had loosened slightly during the flight, and there was concern that they might disrupt the plasma flow around the shuttle’s nose on reentry, potentially causing hot spots on the tiles.
Engineers and astronauts on the ground spent two more days trying different techniques to either remove the gap filler or cut them flush and then instructing the spacewalkers on the techniques. The third space walk took place on 3 August 2005. Before trying the repair, the two spacewalkers installed an amateur radio satellite called PCSat2 on the outside of the station, in addition to some exposure cassettes. For the gap filler removal, the OBSS was fitted with a foot restraint, and the RMS maneuvered Robinson in the restraint to the bottom of Discovery’s nose. Robinson would use his gloved hands in the first attempt to remove the fillers. It turned out that using his hands worked just fine, as both pieces of gap filler popped free with only a tug. Nothing else was needed.
Given that it was the first and what would ultimately be the only time an astronaut got to go underneath a shuttle on a space walk, it was a rather tense time for engineers. But the RMS performed well, even with a relatively heavy mass (Robinson and the OBSS) on the end of it. The OBSS turned out to be a stable work platform. Three days later, Discovery left the ISS and ultimately returned home on 9 August. The mission was hailed as a success. But nobody knew exactly when the shuttle would be cleared for flight again.
Expedition 11 finished out its tasks and eventually returned to Earth on 11 October 2005. Deorbit and reentry were normal. During this mission, Sergei Krikalev added to his time from previous flights to set a record for total time in space of 803 days, nine hours, and thirty-nine minutes, surpassing the previous record of 747 days set by Sergei Avdeyev.
Expeditions 12 and 13 would fly during the next year. Astronaut William McArthur and cosmonaut Valery Tokarev occupied the ISS from October 2005 to April 2006. Pavel Vinogradov and Jeff Williams took over for them starting in April. They were joined by Brazil’s first astronaut Marcos Pontes, who returned home with McArthur and Tokarev after the crew handover. Pontes was flying thanks to Brazil’s ISS hardware contribution.
While engineers modified the ET design, the next major shuttle delay came from mother nature as Hurricane Katrina clobbered the Gulf Coast of the United States in late August. ETs were manufactured at the Michoud assembly facility near New Orleans, and several buildings at the site and one ET itself were damaged by the winds. Thankfully, Michoud was spared damage from flooding. The levees protecting New Orleans failed, causing parts of the city to flood. Thanks to the repairs being completed faster than anticipated, Michoud was back in business by mid-October. It was a credit to the workers at the factory, as several of them were rendered homeless by the storm. It took many months (and in some cases years) for communities in the rest of New Orleans to get back to some semblance normalcy.
STS-121
By 30 June 2006 all was ready as Discovery sat on pad 39B for a launch date of 1 July for the second of two “Return to Flight” missions. The six-person crew was made up of shuttle commander Steve Lindsey; pilot Mark Kelly; and mission specialists Mike Fossum, Lisa Nowak, Stephanie Wilson, and Piers Sellers. Joining them for the ride into orbit was German ESA astronaut Thomas Reiter, who would be joining Expedition 13 once Discovery reached the ISS.
There were two launch scrubs due to weather on 1 and 2 July. A cracked piece of foam that broke off of one of the ET struts threatened to postpone STS-121’s third launch attempt, but NASA managers decided to go ahead since the foam piece was not large and they didn’t find any other problems with the tank. Discovery was ready to go on 4 July. It would be the Fourth of July fireworks show to remember, as thousands flocked to the Florida coast near KSC to watch the display.
At 14:37 EDT, the space shuttle Discovery rocketed into a clear, blue Florida sky. The weather was perfect, and all who watched were treated to quite a show. While some tiny pieces of foam were observed coming off the tank, they were too small to do any damage. The new cameras didn’t detect any debris strikes, and OBSS inspections of the tiles revealed no problems with the shuttle’s heat shield that required additional inspection or repair work. With the foam issues having been dealt with satisfactorily, normal shuttle flight operations could now resume.
Discovery approached the ISS, and after the now-standard rendezvous pitch maneuver, it docked safely. Upon the ship’s docking, the Expedition 13 crew rang the station’s bell two times, and Jeff Williams announced with the now-standard greeting, “Discovery arriving.” That began the start of nine days of docked operations, as transfers were made from the Leonardo MPLM to the ISS from a CBM on the Unity node. Michael Fossum and Piers Sellers conducted three space walks on this flight, with their tasks split between doing some testing work with the OBSS, testing additional shuttle tile repair techniques, and changing out some minor equipment on the U.S. side of the ISS. At the end of nine days, Leonardo was placed back inside Discovery’s cargo bay, and the shuttle returned home with no problems. With these two shuttle test missions out of the way, the path was now clear for ISS assembly to resume.
13
Construction Resumes
With the flight of STS-121 and the success of the thermal protection system inspection and repair techniques tried out on two shuttle flights, ISS construction missions resumed in late 2006. When plans for retirement of the shuttle were announced, NASA indicated that they would fly no more than twenty missions, with nineteen of them being dedicated to ISS assembly and resupply. With STS-114 and STS-121 completed, that left seventeen more missions for the ISS. The remaining flight would be a repair mission to the Hubble Telescope.
STS-115 came next as Atlantis delivered the P3 and P4 solar array truss segments when it docked on 11 September 2006. This was one of the heaviest payloads flown during the shuttle program, weighing about sixteen metric tons (one ton being equivalent to one thousand kilograms, as opposed to an English-measured ton, which weighs slightly less at two thousand pounds). The crew was reduced from seven to six crewmembers to save weight in onboard consumables. During the mission, Canadian Space Agency astronaut Steve MacLean became the first Canadian citizen to operate the SSRMS when the new segments were transferred from the shuttle’s cargo bay to their location on the station’s truss. The solar array delivery and attachment phases went well with no problems. MacLean also became the second Canadian to perform a space walk, which he did with NASA astronaut Heidi Stefanyshyn-Piper.
Heidi Stefanyshyn-Piper, being one of the few women in the astronaut corps to train for EVAs, was very qualified for her work, as she was a salvage diver in the U.S. Navy before joining NASA. Her name is a bit long and cumbersome since she kept her maiden name, Stefanyshyn, to honor her father’s Ukrainian heritage. Heidi was born in the United States in St. Paul, Minnesota, but she is a fluent Ukrainian speaker
thanks to her family’s upbringing. Heidi Stefanyshyn-Piper became only the eighth woman to conduct a space walk.
STS-116 came next in December 2006. As part of that flight, Discovery delivered the P5 truss segment, which was then bolted outboard the P3 and P4 segments with the SSRMS. The arm was used exclusively for the attachment task since there were no plans for any astronauts to conduct an EVA that far away from the station’s airlock. The P5 segment would serve as the attachment point for the P6 solar array truss when it finally got relocated from its central Unity Z1 location on a later mission.
The space walks conducted this time in addition to procedures inside were primarily to reconfigure the station’s electrical system from the Z1 to the main truss, so half the P6 solar panels were unhooked from the power grid and the P4 arrays became the main power supply. Controllers then commanded the port-side arrays on the center-mounted P6 unit to retract in order to give room for the P4 arrays to track the sun properly.
There were some problems during retraction, though, as the arrays kept getting snagged and kinked during the operation. They were only intended to be unfurled in their temporary location for a few months to a year at most, but over three years had passed since they were erected. The array could not remain half-erected, as trying to move unsecured panels with an RMS later could cause all sorts of problems. They needed to be completely folded.
It took a space walk with astronauts Bob Curbeam and Christer Fuglesang using some special tools to help “fluff” the arrays like a set of blinds during retraction to get them to fold in properly. The balky panels finally did so, giving the P4 array a full path of travel. The starboard P6 panels, still generating some power, would be retracted on a later mission. Christer Fuglesang, an ESA representative, was Sweden’s first astronaut, and he conducted three of the four space walks on STS-116 with EVA leader Bob Curbeam, a veteran of STS-98’s Destiny laboratory delivery.
On board, Sunita Williams traded places with Thomas Reiter to join Expedition 14 crewmembers Michael López-Alegría and Mikhail Tyurin, after she performed one of the STS-116 space walks. Expedition 13 crewmembers Pavel Vinogradov and Jeff Williams had returned home in September aboard Soyuz TMA-8 along with spaceflight participant Anousheh Ansari, who had arrived with the Expedition 14 crew aboard Soyuz TMA-9. This type of staggered crew arrangement, with a single astronaut launching and landing on shuttle missions overlapping two ISS Expeditions, would be the norm for the next couple of years. When López-Alegría and Tyurin returned to Earth, Sunita Williams would join Expedition 15’s Russian crew of Oleg Kotov and Fyodor Yurchikhin when they arrived in April 2007.
Sunita Williams’s time on orbit was a pleasant one as she bonded rather well with her Expedition 14 and 15 crewmates. Her ethnic background is half-Indian on her father’s side and half-Slovenian on her mother’s side. She became only the second astronaut of Indian descent after Kalpana Chawla to join NASA and fly in space. Prior to joining NASA, Williams was a naval helicopter aviator. She flew missions in support of Desert Storm and relief to communities in Florida in the aftermath of Hurricane Andrew in 1992.
During her time on the ISS, Williams conducted three space walks with Michael López-Alegría—or Mike L. A., as he is known in Houston. López-Alegría also conducted one Orlan-suited space walk with Mikhail Tyurin prior to STS-116’s arrival. During this period of ISS operations, construction tasks, more than scientific activities, were the order of business, and the staged EVAs got a bit more ambitious as the ISS grew in size. Among the tasks completed were disconnecting coolant lines from an Early Ammonia Servicer unit that would be jettisoned on a later flight and relocating power connection lines on the trusses. Cables for the ISS’s Station to Shuttle Power Transfer System were also hooked up.
On all previous flights to that point, the shuttle remained powered up in order to supply the ISS with added energy for its own systems. Thanks to the Station to Shuttle Power Transfer System, starting with STS-117, the ISS would be generating a surplus of power, and the shuttle’s systems could be shut down to extend their mission life. By doing this, a shuttle could remain docked 50 percent longer on future missions in order to conduct more extensive assembly and resupply tasks.
Extravehicular Activity, American Style
While the Russian Orlan was a very capable suit design, the experience NASA gained on over three decades of EVAs made the EMU a space-going equivalent of a swiss army knife with a plethora of tools at its disposal. During the shuttle program, when a newcomer was accepted into the ranks of the NASA mission specialists, they could opt to focus primarily on robotic arm operations with the RMS or train for EVAs. Not every astronaut necessarily has the build to fit in the suit, but the number of different sizes available for lower torsos, arms, and gloves allow the EMU to fit a large variety of body types.
48. The ISS EMU contains everything an on-orbit handyman needs. Courtesy NASA.
Even then, many consider one of the physical qualities that best helps an astronaut with EVAs is having large arms, or a “gorilla build.” Astronauts such as Dave “Ox” Van Hoften, Dave Wolf, and Scott Parazynski seem better-sized for the suit than some of their colleagues. Since Russian cosmonauts are typically required to perform EVAs in the Orlan, most also have a physical build well suited for the EMU.
Getting into a suit requires a lot of preparation, starting with a prebreathe phase to flush nitrogen from an astronaut’s blood supply. During the shuttle days, astronauts had to prebreathe pure oxygen for about two hours before going outside. During the early ISS assembly program, to help cut down prebreathe time, astronauts would do vigorous exercise on the station’s veloergometer while breathing pure oxygen to flush nitrogen at a faster rate. In both cases, if these tasks weren’t done, nitrogen bubbles could have formed in human tissues due to the reduced pressure of the suit, causing the bends or worse. However, the exercise routine also could be exhausting to crewmembers performing EVAs potentially lasting up to eight hours at a stretch.
With the Quest airlock in place, astronauts could now camp out in a pressurized environment sealed from the rest of the station the night before and flush out the nitrogen in their bodies by breathing pure oxygen at a slightly reduced pressure. The next morning, they would be ready for their EVA tasks and could suit up as normal. Typically one or two other crewmembers would be on hand to help suit up the astronauts going outside.
Donning the suits starts with the waste-management devices. For the males, it is a urine-collection device. It attaches to a male astronaut’s anatomical region with a condom; when he urinates, the fluid is collected in a bag thanks to a one-way valve. Up to 950 cc of urine can be held in the bag. Female spacewalkers wear the Disposable Absorption Containment Trunk (DACT). It looks like a set of tight-fitting boxer shorts and acts like a diaper that can hold up to 900 cc of moisture. The Disposable Absorption Containment Trunk is disposed of after use, unlike the urine-collection device, which has reusable elements. Since women spacewalkers are few in number, the Disposable Absorption Containment Trunks work just fine, and plenty are kept aboard the ISS.
Donning continues with the liquid cooling and ventilation garment. Sweat inside a suit can be dangerous, as it could fog the helmet visor if the humidity level gets too high. To prevent this, cooling water is circulated around the garment through tubes built into it. The Orlan uses a similar garment. Astronauts regulate the water temperature with controls on the chest pack of the EMU. Once the liquid cooling and ventilation garment has been put on, the upper torso is next, and an astronaut puts it on like a large stiff shirt by snuggling up through the waist. The pants and boots come next. Then come the familiar “Snoopy” communications headset (so named for its black-and-white color), the gloves, and finally the helmet.
Unlike the Apollo-era suits, the EMU’s backpack containing the oxygen, batteries, cooling water, and carbon dioxide scrubber bed is integral to the torso, as is the chest pack with the controls. The EMU’s power systems are recharged via a docking rack inside t
he Quest airlock. The astronauts typically are docked with the racks during cabin depressurization and repressurization to save the batteries for the EVA itself.
The EMU helmet contains a pair of flip-down visors for sun shielding and lights to illuminate the work area during night passes. For the ISS program, NASA also added a lipstick-sized television camera above the visor to provide support astronauts inside and controllers on the ground with a first-person view of what the wearer sees. Inside the helmet, near the astronaut’s face, is a drink bag with a straw to help prevent dehydration. An optional food stick can also be fitted in the helmet, but very few astronauts use one, to prevent food particles from floating free.
Most EVA crewmembers typically have at least three pairs of EVA gloves on hand due to wear and tear caused by the work outside. For ISS crewmembers on long-duration missions, new gloves can be flown on cargo supply craft as needed. Because an astronaut needs a little bit of tactile sensation to do their work, the gloves are thinner than other parts of the suit. Even though steps were taken during design of the ISS to minimize sharp edges and corners that could possibly damage a glove, years in Earth orbit can cause surfaces to develop sharper edges and surface pits due to exposure to atomic oxygen and micrometeoroid debris impacts. While moving between work sites, a gloved hand might not feel a tug or a snag. So during an EVA, regular glove checks are performed. If a glove shows abnormal wear to a certain point, an EVA can be terminated early, regardless of how important the tasks are. During EVAs, crew safety comes first.
