The International Space Station

I am directing NASA to develop a permanently manned space station and to do it within a decade.

—President Ronald Reagan, State of the Union Address, January 25, 1984

A space station is an orbiting structure designed to accommodate visiting crewmembers for an extended period. In 1984 the U.S. government envisioned building a continuously manned space station in which scientists would conduct long-term research in a microgravity (near weightlessness, almost zero gravity) environment. The station was to be large and spacious, with room for up to ten crewmembers at a time. The U.S. space shuttle was going to be the workhorse that carried cargo and astronauts to the station and back on a routine basis.

To save money on this expensive undertaking, the United States invited other countries to participate. Eventually, fifteen countries did so, including Russia, which assumed a major role in the project. The space station became an international venture. It also became extremely expensive. The design was changed several times to bring costs down. The development phase alone dragged on for more than a decade. In 1998 construction finally began on the International Space Station (ISS). After five years a small portion of the ISS was in orbit around Earth. Then the space shuttle Columbia exploded. The entire shuttle fleet was grounded while the National Aeronautics and Space Administration (NASA) investigated what went wrong. ISS construction was halted as well because only shuttles are powerful enough to haul heavy pieces of the ISS into space. This was a serious setback for the project.

In January 2004 President George W. Bush (1946-) set forth a new space agenda for the United States: sending astronauts to the Moon and Mars. The plan calls for aborting the shuttle program and ceasing ISS construction as soon as possible. That would mean a space station much smaller than expected, with limited research capabilities. Such a prospect is disappointing to many scientists around the world. However, others believe that even a downsized ISS is a major step on humanity’s journey into outer space.

EARLY VISIONS OF A SPACE STATION

The first serious proposal for a space station was made in 1923 by Hermann Oberth (1894-1989). Oberth is considered one of the fathers of rocket science. His doctoral dissertation was “Die Rakete zu den Planeten-räumen” (“The Rocket into Interplanetary Space”).

Oberth proposed building an orbiting structure called a weltraumstation (space station) that would serve as a launching and refueling station for spacecraft engaged in deep space travel. Six years later he expanded on his ideas in Wege zur Raumschiffart (1929; Methods of Achieving Space Flight ). Oberth’s writings had a profound effect on the young Wernher von Braun (1912-1977), who later became a key developer of rocket science in the United States.

In 1929 Hermann Potocnik (1892-1929; also known as Herman Noordung) published his idea for an orbiting space station. Potocnik’ s spacecraft was wheel-shaped and primarily designed to be an observatory and scientific laboratory.

In 1952 von Braun published a drawing of his vision of a space station. It was a wheel-shaped structure that would orbit 1,075 miles above Earth and serve a variety of purposes. Von Braun envisioned the station aiding in navigation and weather forecasting on Earth and serving as a military outpost, spaceport, and launching platform for ventures into deep space.

According to NASA historians, the von Braun team encouraged NASA to build a space station before sending a man to the Moon. President John F. Kennedy (1917– 1963) decided that the Apollo program should receive priority. However, a space station was always considered the next step after Apollo.

The U.S. Air Force pursued its own version of a space station during the 1960s. The Manned Orbiting Laboratory (MOL) included a large laboratory module that was reached by a Gemini-type spacecraft launched aboard a Titan rocket. The military hoped to use the MOL for reconnaissance missions and for weather observation. The U.S. government spent more than $1 billion researching and developing the MOL. The project suffered constant budget overruns and schedule delays and was finally canceled in 1969. By that time, unmanned reconnaissance satellites were available that could do much of what the MOL was to accomplish. Military astronauts who had been training in the MOL program were transferred to NASA.

THE AMERICAN SKYLAB

Long before an Apollo spacecraft landed on the Moon, NASA planners were looking ahead to their next great project. The Apollo Applications Program (AAP) began in 1963 with a plan to use leftover Apollo hardware in some kind of orbiting station including a laboratory, workshop, and space telescope. When the Apollo 20 mission was canceled in 1970, the AAP inherited a Saturn V rocket. It used the rocket as the launch vehicle for a newly developed station called Skylab.

The Skylab program had two primary goals:

• Prove that humans could live and work in space for extended periods of time
• Expand knowledge of solar astronomy using a space-based telescope

The program was composed of four flights, as shown in Table 5.1.

The station was designed with two solar panels that were folded flat against the rocket during launch. Once in orbit, they were to open up like wings and harness the Sun’s energy to provide electricity for the station. On May 14, 1973, the unmanned Skylab station was launched into orbit. It was damaged during liftoff when a protective shield came loose and smashed against the solar panels, ripping one of them off and damaging the other.

A team of three Skylab astronauts was scheduled to launch the next day. However, their flight was delayed for ten days as engineers assessed the damage to the station. The astronauts, called the Skylab 2 crew, finally launched on May 25, 1973. They successfully docked with the station and began repairing its damaged components. Crewmembers deployed a temporary sail-like shield to replace the torn-off solar panel. Their mission lasted just over twenty-eight days, a new record for Americans in space. This record was bested by the astronauts of Skylab 3 and Skylab 4.

The Skylab station weighed nearly one hundred tons and was about the size of a small three-bedroom house. It included a two-level workshop.

The Skylab 3 mission included two spiders named Anita and Arabella. The spiders were part of an experiment suggested by Judith Miles, a high school student from Lexington, Massachusetts. She wondered if spiders would be able to spin their webs in microgravity. NASA scientists seized on the idea and sent the spiders into space in cages equipped with still cameras and television cameras. The public became enthralled in hearing about the two spiders.

Neither spider adjusted well to the new environment. Arabella’s initial webs were sloppy and lopsided. However, after a few days the spider began spinning web patterns like it would on Earth. Both spiders died during the mission, apparently of dehydration. Their bodies were turned over to the Smithsonian Institution and were still kept there in 2008.

The Skylab was not designed for long-term use. It had no method of independent reboost to keep it from falling out of orbit. As a result, on July 11, 1979, the station reentered Earth’s atmosphere and broke apart over the Pacific Ocean.

Despite its early mechanical problems, Skylab was considered a great success. The total number of hours spent in space by Skylab astronauts was greater than the combined totals of all space flights made up to that time. NASA gained valuable knowledge about human performance under microgravity conditions.

SOVIET AND RUSSIAN SPACE STATIONS

When the Soviets realized that they could not beat the Americans to the Moon during the 1960s, they turned their attention to other space goals. In 1971 they put the first of many Soviet space stations into orbit around Earth. Soviet and Russian cosmonauts spent the next three decades gaining valuable experience in long-duration space flight.

The Salyut Series

On April 19, 1971, the Soviet space station Salyut 1 was launched from the Baikonur Cosmodrome in what is now Kazakhstan. The station was cylindrically shaped and approximately twelve meters long (about thirty-nine feet) and four meters (thirteen feet) wide at its widest point. It was placed into orbit approximately 200 kilometers (124 miles) above Earth.

The station was built so that Soviet scientists could study the long-term effects on humans living in space. A crew of three cosmonauts flew aboard Soyuz 10 to the station a few days after the station was placed in orbit. However, they were unable to dock with it, so they were forced to end their mission early and return to Earth. In June 1971 the Soviet spacecraft Soyuz 11 successfully docked with the station, and three cosmonauts inhabited it for twenty-four days. They were killed as they returned to Earth, when a valve opened on their spacecraft and allowed it to depressurize. At that time, cosmonauts did not wear pressurized space suits during launch or reentry.

The Soviet space agency canceled future flights to the station and began an extensive redesign of the Soyuz spacecraft. In October 1971 Salyut 1 fell into Earth’s atmosphere and was destroyed. In total, the Soviets put seven Salyuts into orbit. (See Table 5.2.) These stations were visited by cosmonauts and scientists from a number of countries, including France, India, and Cuba. In 1984 three Soviet cosmonauts spent 237 days aboard Salyut 7. This was a new record for human duration in space. Salyut 7 was deorbited in February 1991.

Mir

In February 1986 the Soviet Union launched the new space station Mir into orbit. Mir was to be Russia’s first continuously occupied space station. Even though originally planned to stay in orbit for five years, Mir survived for fifteen years. It finally tumbled to Earth in 2001.

Russian cosmonauts repeatedly set and broke space duration records aboard the Mir station. Vladimir Titov (1947–) and Musa Manarov (1951–) reached the one-year milestone when they completed 366 days in space in 1988. By 1995 the record was 437.7 days, set by Valery Polyakov (1942–). As of 2008, this was still the record.

The Mir is also famous for its nongovernmental inhabitants. Beginning in the 1980s the Soviet space program suffered financial difficulties. To raise funds, the space agency sold seats on Mir to a variety of foreign astronauts and adventurers. In 1990 the Japanese journalist Tohiro Akiyama (1942–) became the first citizen of Japan to fly in space and the first private citizen to pay for a space flight. Akiyama’s television network paid $28 million to send him on a seven-day mission to Mir. In 1991 the British chemist Helen Sharman (1963–) spent eight days in space after winning a contest sponsored by a London bank.

Shuttle-Mir Missions

As early as 1978 NASA proposed a joint U.S.-Soviet mission to a Salyut station. NASA engineers discussed possible ways to dock a U.S. space shuttle with the station and hoped to put a scientific payload on board the station.

Scientific hopes were overshadowed by international politics. In 1979 the Soviet Union began a war in Afghanistan. Two years later the Soviet government imposed martial law in Poland to suppress dissenters. The U.S. response to both incidents was a sharp reduction in cooperative efforts between the two countries. The Soviet empire began to dissolve during the late 1980s and was officially ended in 1991, when it separated into many independent countries. The largest of these was Russia, which inherited most of the Soviet space program.

In June 1992 U.S. president George H. W. Bush (1924-) and Russian president Boris Yeltsin (1931-2007) signed the Agreement between the United States of America and the Russian Federation Concerning Cooperation in the Exploration and Use of Outer Space for Peaceful Purposes. NASA and the Russian Space Agency (which had been recently created) worked out a plan for joint shuttle-Mir missions. Both agencies considered this a prelude to a joint U.S.-Russian space station. In fact, the shuttle-Mir program was officially called “Phase 1” at NASA. Phase 2 was to be the assembly of a space station. Phase 3 was to be the operation of a space station with the gradual addition of scientific and operational capabilities.

NASA set four goals for Phase 1:

• Learn to work with international partners
• Reduce the risks associated with developing and building a space station
• Gain American experience in long-duration missions
• Perform research in life sciences, microgravity, and environmental programs

In 1993 President Bill Clinton (1946-) met with Yeltsin and agreed to continue cooperative efforts in space exploration. On February 3, 1994, the space shuttle Discovery launched for the first time ever with a cosmonaut aboard. Exactly a year later the shuttle was launched again. This time the shuttle flew near Mir. In June 1995 the shuttle Atlantis docked with Mir. The shuttle was carrying four cosmonauts besides its American crew.

Between 1994 and 1998 space shuttles docked ten times with Mir. Figure 5.1 depicts a shuttle docked to the Mir space station. American astronauts logged nearly one thousand days of orbit time during Phase 1. One of them, Shannon Lucid (1943-), set the women’s record for space flight duration: 188 days. A summary of all Phase 1 accomplishments is given in Table 5.3.

Mir Mishaps

When the first Americans arrived at Mir in 1995, the station had already been in orbit for nine years. They found a cramped and crowded spacecraft bulging with hoses, cables, and scientific equipment. Every closet and storage space was crammed full. Some gear and tools floated around, because there was no space left to stow or fasten them. Over the years, water droplets had escaped from environmental control systems and now clung to delicate electronics. Mir’ s systems were plagued by computer crashes and battery problems. The cosmonauts spent the vast majority of their time doing repair and maintenance tasks.

On February 23, 1997, a fire broke out aboard Mir when a cosmonaut lit a lithium perchlorate candle. Flames one-foot long shot out of the unit and ignited the canister. At the time, there were six men aboard the station: four Russians, a German, and an American. The fire quickly filled the spacecraft with smoke. The Russians ordered everyone to evacuate the station. However, the fire blocked access to one of the two Soyuz capsules that served as their lifeboat. Only three men would be able to escape if the hull was breached.

The men fought the flames with towels and a few working fire extinguishers. Many of the ship’s fire extinguishers malfunctioned or were bolted down and could not be released. After fifteen minutes the fire died, apparently snuffed out by lack of oxygen in its immediate area. The crew had donned respirators and floated quietly, barely moving for hours as they waited for the ship’s ventilation system to remove the smoke.

Russian mission control downplayed the fire to the public and American officials, telling them it was a minor and isolated event. In truth, there had been a similar occurrence several years before in which a candle had burst into flames. Neither the most recent crew nor the public had been informed of that incident. Secrecy had always been a hallmark of the Soviet space program, and this culture persisted in the Russian space program of the 1990s.

The fire in February 1997 was followed by even more problems aboard Mir. Only a week later, a camera failed during a docking exercise and the station was nearly rammed by a supply ship. In late March the cooling system failed. The temperature rose to 95 degrees Fahrenheit on the station, and it was permeated by an odor of antifreeze. High carbon dioxide levels forced the crew to limit their physical activity.

Throughout the spring the crew struggled to repair the ailing ship. Another calamity struck on June 27, 1997, when the crew was conducting a docking test using a Progress supply ship. The cosmonauts did not trust the station’s television images of the maneuver, so they tried to guess the distance by eyesight. The freighter slammed into the station and cracked its hull. Robert Zimmerman describes this incident in detail in Leaving Earth: Space Stations, Rival Superpowers, and the Quest for Interplanetary Travel (2003).

According to Zimmerman, the Mir crew felt their ears pop as the station began to lose pressure, and they could hear oxygen hissing out into outer space. The crash had breached the hull of the module called Spektr. Mission

control ordered the crew to close the hatch to that module to seal off the breach. This was impossible because previous crews had run electrical cables and wires through the doorway, so the hatch could not be closed all the way. The crew frantically began cutting and unhooking the wiring. Finally, they closed the door, isolating themselves in the base unit away from the leak.

The impact with the freighter knocked the station into an uncontrollable spin. Furthermore, disconnection from Spektr had cut power to vital systems. The crew floated in darkness for nearly thirty hours. Finally, they used the rockets on the Soyuz lifeboats to nudge the station out of its spin and into proper position.

The mishaps aboard Mir could not be downplayed anymore. Politicians and the press in the United States called for NASA to stop sending American astronauts to the trouble-prone station. Despite the pressure, NASA and the White House felt it was important to complete Phase 1. Shuttle flights continued to Mir throughout 1997 and into 1998.

AN INTERNATIONAL EFFORT

In his State of the Union Address (January 25, 1984, http://reagan2020.us/speeches/state_of_the_union_1984.asp), President Ronald Reagan (1911-2004) directed NASA to develop a space station before the end of the decade. The project was expected to cost the United States only around $8 billion because of the participation of foreign governments. By 1988 Canada, Japan, and nine European countries had signed formal agreements with the United States to participate in the project. Reagan named the new space station Freedom.

Freedom

Freedom was to include three separate components: a pressurized base unit in which the crew would live and work and two automated platforms that would support scientific experiments and observations of Earth’s climate. At that time, designers envisioned a station that could accommodate a crew of up to ten people.

The project was plagued immediately by financial and technological problems that continued to get worse. Development costs increased even as NASA’s budget shrank. Congress demanded several redesigns to save money. NASA eliminated the two automated platforms and scaled back the base unit. Each redesign resulted in a smaller station with less usable space and less electrical power available to scientists. NASA’s foreign partners became increasingly annoyed about the design changes.

Meanwhile, the Space Shuttle Program was enmeshed in its own difficulties. The space shuttle was crucial to the station program, because it was to be the only means by which American flight crews could reach the station. The catastrophic breakup of the space shuttle Challenger in 1986 grounded the entire shuttle fleet for more than two years. It also raised questions about the safety and quality of NASA’s operations.

Even as the space station shrank in volume, its weight increased. This required shuttle design changes to accommodate the extra weight. It was also decided to include some kind of lifeboat capability in the station in case its crew had to leave in an emergency. By December 1990 the cost of Freedom was estimated at $38 billion. This included the cost of shuttle launches required to build the station.

In 1991 a congressional committee recommended that NASA cancel the development of Freedom. A vote was held by the U.S. House of Representatives to determine its fate, and an amendment was passed to continue the program. This was the first of nearly two dozen votes that would take place over the next decade in the House and U.S. Senate on the fate of the space station. Each time the program was allowed to continue; however, some of the votes were extremely close. For example, in a June 1993 vote the station survived by a one-vote margin.

Station Alpha

When President Clinton took office in 1993, he ordered a sweeping revision to cut costs in the space station program. By that time, NASA had already spent more than $11 billion on design costs alone. However, not one piece of hardware had been launched into space. NASA designers presented the president with several different options for station components and functions, and he selected the plan Design Alpha. The new station was unofficially named Station Alpha.

By this time, the Soviet Union had collapsed. The Clinton administration began talks with the new Russian government and welcomed Russia’s eagerness to participate in the space station project. According to Marcia S. Smith of the Congressional Research Service, in NASA’s Space Station Program: Evolution and Current Status (April 4, 2001, http://www.hq.nasa.gov/office/pao/History/smith.htm), President Clinton saw Russian participation as a way to improve foreign relations and put pressure on the Russians to abide by newly signed ballistic missile agreements. He also wanted to provide Russian scientists with jobs to keep them from selling valuable information to the United States’ enemies. NASA estimated that Russian participation would cut $2 billion off the $19 billion cost of completing Station Alpha and speed up its development by a year.

On September 2, 1993, the two countries signed the Joint Declaration on Cooperation in Space. By the end of the year, NASA and the Russian Space Agency had ironed out a detailed work plan for what was now called the International Space Station.

The ISS Plan

It was decided that the ISS would comprise individual segments called modules that would dock together to form the station. Each module was to be constructed on the ground and then launched into space. The space shuttle was expected to carry the heaviest loads to the station. Russia agreed to transport supplies and propellants to the ISS aboard its unmanned Progress spacecraft. In addition, Russian Soyuz spacecraft were offered as the station’s lifeboats.

A rotating schedule for the first four modules was developed in which Russia would build the first and third modules and the United States would build the second and fourth modules. NASA agreed to pay for one of the Russian modules.

The collaboration with Russia raised some concerns among U.S. politicians and scientists. They publicly expressed fears that the cash-strapped Russian government would not be able to fulfill its obligations to the program. NASA had given the Russian Space Agency responsibility for two of the most important modules in the station. Failure to deliver them would cripple the entire project. U.S. fears grew even greater during the late 1990s as problems surfaced on the Russian space station Mir.

On January 29, 1998, the U.S. government signed the Agreement among the Government of Canada, Governments of Member States of the European Space Agency, the Government of Japan, the Government of the Russian Federation, and the Government of the United States of America Concerning Cooperation on the Civil International Space Station (http://www.canlii.org/ca/as/1999/c35/). This document outlined the agreement among the partners for design, development, operation, and utilization of the ISS. The previous year the United States had signed a separate agreement with Brazil giving it utilization rights in exchange for supplying ISS parts. Table 5.4 lists the nations that are ISS partners.

In early 1998 it was expected that at least forty spacecraft launches spread over five to seven years would be required to assemble more than one hundred components into the ISS. At that time, the station was designed for a crew of seven people. The space station was expected to be completed by 2005 or 2006 and cost the United States $26 billion to complete.

ISS Assembly Begins

On November 20, 1998, a Russian Proton K rocket was launched, carrying Zarya, the first module of the ISS. The Russians built Zarya, but the Americans paid for it. It was to be a U.S. component of the station. The module provides control and cargo capabilities. Zarya was self-propelled and was designed to keep the station in orbit until the service module arrived. After that it would serve as a passageway, storage facility, docking port, and fuel tank. Zarya weighed forty-four thousand pounds at launch.

Two weeks later, the shuttle Endeavour carried the module Unity to the station. Figure 5.2 shows the two modules docked together. Zarya is on the left and Unity is on the right. Unity is an American-built module with six docking ports for attachment to other modules. It provides a node (link) between modules. It is basically a passageway with some internal storage space. Unity is eighteen feet long and fifteen feet in diameter and weighed over twenty-five thousand pounds at launch.

Two more shuttle crews visited the ISS in 1999 and 2000 to outfit the modules with logistical equipment and supplies. On July 12, 2000, the Russians launched the service module Zvezda into space aboard a Proton K rocket. This module was built and funded by the Russians and was to be the core of their segment.

It included functions for station control, navigation, communications, and life support systems (including the crew quarters). At that time, it was expected that many of

these functions would be taken over by an American module to be added later. Zvezda’s design was based on the core module of the Mir space station. Zvezda is forty-three feet long with a wingspan of ninety-eight feet and weighed forty-two thousand pounds at launch. It includes docking ports for Russian Soyuz and Progress spacecraft. Figure 5.3 shows the three modules hooked together. Zvezda is on the far left.

Throughout the summer of 2000 visiting Russian and American crews continued outfitting the modules and assembling the station. The station was also visited by an unmanned Russian Progress spacecraft carrying consumables (food and water), spare parts, and propellants.

On November 2, 2000, the first crew to actually inhabit the ISS arrived aboard a Soyuz spacecraft. It was called ISS Expedition 1. It included two Russian cosmonauts and one American astronaut. (See Table 5.5.) Resident crews have included only U.S. and Russian members. Many temporary visits have been made by NASA astronauts aboard space shuttle flights. (See Table 4.4 in Chapter 4.) Table 5.6 lists the temporary visits to the ISS by astronauts from foreign space agencies.

The Expedition 1 crew lived aboard the station until March 2001. They were visited by two shuttles, one of which brought the American lab module Destiny. This module was to be the primary research laboratory for U.S. payloads. It included many racks that could support a variety of electrical and fluid systems during the performance of experiments. It also contains the control center for the ISS robotic arm.

In March 2001 the Expedition 2 crew arrived at the station aboard shuttle Discovery. The Expedition 1 crew returned to Earth aboard the space shuttle, leaving their Soyuz spacecraft at the station to serve as a lifeboat. The Expedition 2 crew included two American astronauts and one Russian cosmonaut. It had been decided to swap out the Expedition crews every four to six months and to rotate back and forth between crews that were predominantly Russian and crews that were predominantly American.

The Expedition 2 crew brought the Leonardo multipurpose logistics module (MPLM). MPLMs are reusable pressurized shipping containers designed to be temporarily attached to the ISS for unloading. They are transported back and forth on space shuttles and carry a variety of cargo, equipment, and experiment racks. The Leonardo module was named by the Italian company that built it. It was loaded with garbage (expired batteries, used filters, etc.) for its return trip to Earth.

The Expedition 2 crew also attached the station’s remote manipulator system. This is a robotic arm that was nicknamed Canadarm2, because it was built by Canadian companies. The space shuttle fleet utilizes another robotic arm called Canadarml.

When the space shuttle Endeavour visited the ISS in April 2001, the crew included the European Space Agency (ESA) astronaut Umberto Guidoni (1954–). He was the first European to board the space station.

Tito Comes Aboard

Also in April 2001 the Russians sent the first taxi to the station to replace the Soyuz lifeboat left by the Expedition 1 crew. The taxi crew included the U.S. millionaire Dennis Tito (1940–). A year earlier, Tito had paid $20 million for a visit to the Mir space station. When the Russians decided to deorbit Mir, they rescheduled Tito for a trip to the ISS. They hoped he would be the first of many space tourists to pay to fly on ISS taxis. The Russian Space and Aviation Agency (Rosaviakosmos) desperately needed the money.

NASA and the European partners in the ISS were not happy with the decision. When Tito and the two cosmonauts showed up at the Johnson Space Center for training, NASA would not let Tito entry the facility. The cosmonauts responded by refusing to undergo training. The standoff resulted in a flurry of negotiations between NASA and Rosaviakosmos. The Americans finally agreed to allow Tito to train in the United States, but they continued to argue that he posed a safety risk to the station and banned him from the American segments of the ISS. NASA repeatedly asked Rosaviakosmos to postpone Tito’s flight, but the Russians would not agree.

On April 28, 2001, a Soyuz blasted off with Tito and the two cosmonauts aboard. Two days later it docked with the ISS. Tito spent his time aboard ISS in the Russian segment taking pictures of Earth and listening to opera. The crew stayed at the station for four days before returning to Earth aboard the old Soyuz lifeboat.

The Price Goes Up

In April 2001 NASA announced that the U.S. cost to complete the ISS by 2006 was going to be $4 billion more than expected. The Clinton administration responded by establishing the ISS Management and Cost Evaluation Task Force to assess the project. In November 2001 the task force released the Report by the International Space Station (ISS) Management and Cost Evaluation (IMCE) Task Force to the NASA Advisory Council (ftp://ftp.hq.nasa.gov/pub/pao/reports/2001/imce.pdf), which called for a serious downsizing of the ISS.

The task force recommended that the ISS be configured for only a three-person crew. Previous plans had called for a seven-person crew. It noted that scientists were not happy with this proposal because they feared it would “have a significant adverse impact on science.” However, the task force noted that the cutback was necessary to save money and suggested that some of the research planned for the ISS could take place aboard space shuttle flights instead.

The task force recommended many management changes within NASA to save money and suggested that the agency prioritize its research goals for the station. One goal considered crucial was the installation of a centrifuge. A centrifuge is a machine commonly used in research to separate different substances, to remove moisture, or to simulate certain gravitational effects. The task force noted that NASA kept putting off centrifuge installation on the ISS, much to the disappointment of the scientific community.

The task force called for NASA to establish a specific “end state” for station construction that could be achieved within NASA’s existing budget. At that point, station construction would be complete and a much cheaper operation stage could begin. The task force recommended that several planned ISS features be eliminated, such as a crew return vehicle, a propulsion module, and a habituation module called Node 3.

The task force issued the report only days before Bush was declared the new president by the U.S. Supreme Court. The ISS project had now fallen under the terms of four U.S. presidents. The Bush administration agreed with the task force’s findings. The end state recommended by the report was called the core complete point. Bush appointed a new NASA administrator, Sean O’Keefe (1956–), and charged him to achieve core complete as soon as possible. NASA estimated that construction could be completed by 2004.

The United States’ international partners were not happy with the plan for a smaller crew size because it meant fewer chances for their personnel to visit the station. Furthermore, many scientists were disappointed with the reduction in research potential afforded by the smaller station.

The Expeditions Continue

By the end of 2001 the station had been visited by the Expedition 3 and Expedition 4 crews, which included three members each. These crews installed Pirs, a new Russian docking and airlock module, and began construction on the truss. The truss is a long girderlike structure that is perpendicular to the row of existing modules. The truss is designed to hold the solar panels that power the station and to hold any new modules constructed in the future.

Deliveries of food, water, and supplies to the ISS continued to occur every few months aboard automated Russian Progress spacecraft. These vehicles were then loaded up with unneeded equipment, wastewater, and trash, which burned up with the vehicles during reentry to Earth’s atmosphere.

The Russian Soyuz lifeboat docked to the ISS was exchanged every six months by taxi crews. In October 2001 a three-member team including two Russian cosmonauts and an ESA astronaut visited the station as part of mission Andromède. They exchanged the Russian Soyuz lifeboat and conducted a ten-day scientific experiment aboard the station. The ESA astronaut was Claudie Haigneré (1957–), the first European woman to visit the ISS.

In April 2002 another taxi crew visited the ISS. This time it included another space tourist: the South African Internet entrepreneur Mark Shuttleworth (1973–). He paid approximately $20 million to visit the space station.

After two years of negotiation, the ISS partners had worked out an agreement specifying who could visit the station. In November 2001 they signed the Principles Regarding Processes and Criteria for Selection, Assignment, Training, and Certification of ISS (Expedition and Visiting) Crewmembers (http://www.spaceref.com/news/viewsr.html?pid=4578). The agreement listed strict requirements regarding the personal character and communication skills of any visitor. It disqualified anyone found to have a drinking or drug problem, those with poor employment or military records, convicted criminals, people who had engaged in “notoriously disgraceful conduct,” and anyone known to be affiliated with organizations that wished to “adversely affect the confidence of the public” in the space program. Visitors also had to speak English.

Shuttleworth passed the review process and launched aboard a Russian Soyuz rocket on April 25, 2002, with a Russian cosmonaut and an Italian flight engineer. Two days later they entered the station. Shuttleworth performed some simple scientific experiments while on board and conducted many interviews with schoolchildren. He and the taxi crew spent eight days aboard the ISS.

Throughout the remainder of 2002 the station was visited by the crews of Expedition 5 and Expedition 6, who continued the construction of the ISS truss. A Soyuz taxi flight launched in October of that year included a visiting astronaut from the ESA. Frank De Winne (1961–) and two taxi cosmonauts spent eight days at the station before returning to Earth.

The last visitors of the year came aboard the space shuttle Endeavour. The orbiter docked at the ISS in late November to deliver the Expedition 6 crew and a new truss segment. In early December the shuttle returned safely to Earth carrying the Expedition 5 crew. It was the sixteenth American shuttle flight to the space station, and it was to be the last for a long while.

ISS Assembly Halts

On February 1, 2003, the space shuttle Columbia broke apart as it entered Earth’s atmosphere over the western United States. The shuttle had been on a research mission and did not visit the ISS. The catastrophe killed the seven crewmembers and shook the U.S. space program to its core. An investigation revealed that the shuttle’s thermal protection tiles were likely damaged by a foam strike shortly after launch. During reentry, hot gases seeped past the tiles into the orbiter structure, and the resulting turbulence tore it apart.

The entire shuttle fleet was grounded. The flights that were scheduled to deliver truss segments and research facilities to the ISS in 2003 were canceled. There was no other way to transport these heavy components to the ISS. The Russian Soyuz spacecraft could carry only around five thousand pounds, compared to the thirty-six-thousand-pound capacity of the space shuttle. Russia’s automated Progress spacecraft could carry even less weight, only one thousand pounds. The ISS assembly came to a halt.

THE COST OF WAITING

The shutdown of the shuttle program had a number of operational and cost effects on the ISS. In September 2003 the U.S. General Accounting Office (GAO; now the U.S. Government Accountability Office) released the report Space Station: Impact of the Grounding of the Shuttle Fleet (http://www.gao.gov/new.items/d031107.pdf). The GAO noted that modules and other equipment already ready to fly to the ISS would have to be unpacked, undergo maintenance, be repacked, and retested before flight. Batteries had to be recharged due to prolonged storage. All these problems resulted in unexpected costs in NASA’s ISS program.

Grounding the shuttle had negative effects on ISS research projects. NASA had planned to launch three major research facilities to the station during 2003. Onboard experiments had to be conducted using existing facilities. However, some of this equipment needed to be repaired or even replaced, particularly refrigeration and freezer units in the science section. These units had experienced a few failures. NASA had planned to replace them during 2003 with the launch of a new and larger cold-temperature facility.

The GAO found that the shuttle delay affected the safety of the ISS. NASA had planned to transport a new on-orbit gyro to the station in March 2003 to replace a broken unit. The station includes four gyros that maintain the structure’s orbital stability and permit navigational control. NASA scientists feared that problems could arise in the station’s three remaining working gyros during a prolonged delay in shuttle flights. NASA had also planned to finish installing shielding on the Zvezda module in 2003. Zvezda houses the expedition crews. The module is supposed to be covered with twenty-three shielded panels to protect it from impacts by space debris. However, at that point, only six panels had been installed. Every day that went by without the additional shielding increased the risk that the module could be struck and damaged by debris.

The shuttle delay also affected the United States’ ISS partners. The original cost-sharing plan was worked out in the 1998 intergovernmental agreement on space station cooperation. This plan calls for NASA to pay the entire cost for ground operations and common supplies for the station. NASA is then reimbursed by the partner countries for their share, depending on their level of participation. Partner countries also fund operations and maintenance for any elements they contribute to the ISS, any research activities they conduct, and a share of common operating expenses. The GAO concluded that these costs would have to be adjusted as the shuttle fleet remained grounded and planned activities were canceled.

The GAO estimated that between 1985 and 2002 the United States spent $32 billion on the ISS.

THE EXPEDITIONS ARE DOWNSIZED

The ISS partners decided to downsize future station crews to only two people. This made it easier for the Russians to assume all responsibility for resupplying the crew with food, water, and other necessities. In April 2003 the two-member Expedition 7 crew flew to the station aboard a Soyuz spacecraft. Unable to proceed with assembly, they were kept busy maintaining the station and performing limited scientific research. One of the largest drawbacks to ISS science is the presence of only two crewmembers. The number of new and continuing experiments had to be reduced so the crews could devote more time to station maintenance and operation.

The crews of Expeditions 8 through 11 consecutively occupied the ISS into October 2005. The Expedition 12 crew brought along the space tourist Greg Olsen (1945–), who returned to Earth with the Expedition 11 crew. Expedition 13 included a visit by the Brazilian astronaut Marcos Pontes (1963–), the first Brazilian to visit the space station. Another visitor, the ESA astronaut Thomas Reiter (1958–) of Germany, boarded the ISS during Expe-dition 13 and remained for more than 160 days to conduct a long-term science experiment.

The Soyuz TMA that carried the Expedition 14 crew to the station included the first woman tourist into outer space. The Iranian-American entrepreneur Anousheh Ansari (1966–) reportedly paid $20 million to Russian authorities to take the flight. Ansari is best known for her sponsorship (along with her brother-in-law) of the Ansari X Prize that awarded $10 million in 2004 to the developers of SpaceShipOne, the first commercially funded private spacecraft to carry a human passenger into space.

During Expeditions 14 through 16, NASA rotated its flight engineers on the ISS at irregular intervals, meaning that some flight engineers were members of two Expedition crews. The space tourist Charles Simonyi (1948–), a Hungarian-born businessman, accompanied the Expedition 15 crew to the ISS. In October 2007 space shuttle astronauts and Expedition 16 crewmembers attached the new live-in compartment called Harmony to the space station. The Italian-made compartment adds approximately twenty-five hundred cubic feet of living and working space. The Expedition 16 crew was visited by the space tourist Sheikh Muszaphar Shukor (1972–), a surgeon from Malaysia and the first practicing Muslim to visit the station.

Table 5.7 lists all the ISS missions flown as of December 2007. From the time that assembly began, the United States made twenty-three flights to the ISS, and the Russians made forty-four flights. Table 5.8 lists the major components installed on the ISS as of December 31, 2007.

A NEW PLAN FOR THE ISS

In January 2004 President Bush announced a new plan for the U.S. space program. This plan calls for retirement of the space shuttle fleet by 2010. The president also wants to end ISS assembly as soon as the core complete configuration is obtained and eliminate all ISS research projects that do not support the new plans for space travel. The core complete ISS would support a crew of only three people and not include some of the modules, habitat enhancements, and scientific facilities and equipment originally planned for the space station.

The plan for a downsized ISS was criticized by the agency’s international partners and by many scientists. The small crew size was a major point of contention. According to the National Research Council of the National Academies and National Academy of Public Administration, in Factors Affecting the Utilization of the International Space Station for Research in the Biological and Physical Sciences (2003), at least 2.5 crew

members per expedition are required to maintain and operate the ISS. Thus, a crew of three people would have very little time to conduct scientific experiments.

In 2005 the NASA administrator Michael D. Griffin (1949–) appeared before the U.S. House of Representative’s Committee on Science and Technology to provide an update on NASA’s plans for the future, including assembly of the ISS. Griffin stated that that the agency planned to assemble enough infrastructure on the station to house a six-person crew and to allow “meaningful utilization” of the ISS.

In NASA: Challenges in Completing and Sustaining the International Space Station (July 24, 2007, http://legislative.nasa.gov/hearings/7-24-07%20Chaplain.pdf), Cristina T. Chaplain of the GAO outlines NASA’s most recent plans for completing the assembly of the ISS. Chaplain notes that NASA intends to finish ISS assembly in 2010 and operate the station through 2016. The Space Shuttle

Program is scheduled to end in 2010, and NASA’s new spacecraft (the Ares series) will not be operational until approximately 2015. During this five-year period NASA plans to rely on commercial providers and its international partners to transport crews and supplies to the station.

Figure 5.4 gives an overall view of the ISS as of November 2007. Figure 5.5 names the major components that will comprise the completed station. As of December 2007 major components yet to be transported to the ISS include the Russian-supplied research module and multipurpose laboratory; the ESA-supplied Columbus laboratory module, Node 3, and Cupola (an observatory to be attached to Node 3); the Japanese-supplied experiment module, pressurized module, experiment logistics module, and remote manipulator system; and the Canadian-supplied special purpose dexterous manipulator.

As of January 2008, NASA had twelve shuttle flights to the ISS on its flight manifest for 2008 and beyond. (See Table 4.5 in Chapter 4.) Chaplain states that if NASA’s schedule gets delayed for any reason, certain elements planned for the ISS —specifically the Node 3 connector and the Cupola observatory—may not get delivered to the station.

ISS SCIENCE

The ISS was intended to be a world-class laboratory for conducting experiments under microgravity conditions. Three broad areas of research are conducted aboard the station: life sciences, biomedicine, and materials processing. The chief goal of life sciences and biomedicine research is to determine the effects of long-duration space travel on humans.

The Station’s Glovebox

One of the difficulties of performing typical chemistry experiments in space is the microgravity condition. Liquids will not stay inside beakers or test tubes because they form into droplets of various sizes and float away. This could be extremely dangerous for the crew and the station’ s electronic components. To overcome this obstacle, NASA and

ESA engineers developed an enclosed work space for the ISS called the microgravity science glovebox (MSG).

The MSG includes a pair of built-in gloves that crewmembers can use to handle tools and equipment within the box. The MSG was installed in the American Destiny module by the Expedition 5 crew. Figure 5.6 shows a slice of the cylindrical Destiny module. The experimental racks are positioned around the outside of the circle. An astronaut stands at the MSG research station.

The MSG is used to handle chemicals or burning or molten specimens in experiments involving fluid physics, materials science, biotechnology, and combustion science.

Materials on the International Space Station Experiment

One of the goals of space science is to determine the effect of space exposure on various materials. The ISS features suitcaselike containers called Materials on the International Space Station Experiment (MISSE) Passive Experiment Containers that are attached to the outside of the station. In 2006 more than eight hundred different substances were carried in MISSE containers, including samples of paints and coatings that may be used on future spacecraft. In addition, millions of basil seeds were exposed to the harsh conditions of space in the MISSE containers.

The Minus Eighty Degrees Celsius Laboratory Freezer

In 2006 ISS astronauts installed the station’s Minus Eighty Degrees Celsius Laboratory Freezer (MELFI). The MELFI allows for fast freezing of biological and life science samples. Scientists also plan to the use the freezer to store astronauts’ blood and urine samples for later analysis on Earth. In particular, researchers are interested in the effects of long-term spaceflight on levels of vitamins D and B6 in the body. Previous research indicates that these vitamins are depleted during long space visits. The depletion is believed to be linked to the bone loss that plagues astronauts exposed to microgravity for long periods.

Bone Loss

Scientists have known for some time that human bones in the legs and feet undergo deterioration during prolonged stays in space. This was first discovered in Soviet and Russian cosmonauts who spent many months aboard space stations. Scientists believe the effect is due

to the lack of mechanical loading in microgravity. Mechanical loading refers to the weight of the upper body pressing down on the lower body as a person’s body is pulled toward the ground by gravity on Earth. The type of bone loss and muscle deterioration experienced by space travelers is similar to that resulting from prolonged bed rest. It has long been known that using legs and feet keeps them healthy. In a spaceship people do not experience the force of gravity or the downward load of the upper body. Also, they rarely use muscles in their legs and feet to move around. They rely much more on muscles in their arms and upper body to maneuver through hatches and accomplish tasks.

During the Russian Mir program, cosmonauts reported that the skin on the soles of their feet became very soft. They also lost muscle tone in their legs and feet due to lack of use. These factors caused them great difficulty walking when they returned to Earth. Scientists incorporated exercise regimens on the ISS to help prevent these problems. For example, stationary bicycles help crewmembers maintain foot muscle strength. However, the exercises have had little effect on bone loss.

Historical data show that humans experience a rate of bone loss in space of approximately 1% to 2% per month. This means a bone loss of 12% to 24% per year. Scientists know that the bone loss problem has to be resolved before humans can make interplanetary journeys. A trip from Earth to Mars could take as long as six months. Crewmembers have to be able to walk on the planet’s surface when they get there.

In “How Long Does It Take to Rebuild Bone Lost during Space Flight” (February 26, 2007, http://www.nasa.gov/mission_pages/station/science/subregional_bone.html), NASA reports on the results of a four-year study of the long-term effects of microgravity on sixteen ISS crew

members. Researchers find that astronauts in Expeditions 2 through 8 lost an average of approximately 11% of their total hip bone mass during a typical six-month mission. Bone scans performed one year after the astronauts had returned to Earth indicate that much of the bone had regrown; however, bone structure, bone density, and hip strength were not fully recovered.

ISS CREW TRAINING

The ISS Expedition crews undergo extensive training at facilities around the world. Figure 5.7 shows the locations of these training facilities, including:

• Johnson Space Center (JSC)—the JSC is located in Houston, Texas. This is the primary training center for Expedition crews. It features laboratories, classrooms, and simulators to prepare crewmembers for living and working aboard the ISS .
• Kennedy Space Center (KSC)—the KSC is located on Merritt Island, Florida, next to the Cape Canaveral Air Force Station. This is the launch site for shuttle flights. Cargo bound for the ISS is packed and loaded here. Crewmembers familiarize themselves with ISS components and practice launch procedures at the KSC.
• Canadian Space Agency (CSA) Headquarters—the CSA headquarters is located in Quebec, Canada. Canadian companies built the remote manipulator system (the robotic arm known as Canadarm2) used on the ISS. Expedition crewmembers undergo robotics training at this location to familiarize themselves with the Canadarm2.
• Gagarin Cosmonaut Training Center—this center is located in Zvezdny Gorodok (Star City), Russia. The training facilities are similar to those at the JSC, including classrooms, laboratories, and simulators. Expedition crewmembers learn about the Russian modules of the ISS and train for spacewalks in the center’s Hydrolab (a forty-foot-deep pool).
• Baikonur Cosmodrome—the Cosmodrome is located in Baikonur, Kazakhstan. This is the launch site for Russian Soyuz flights to the station. Expedition crews scheduled to fly aboard Soyuz spacecraft practice launch procedures at the Cosmodrome.