The International Space Station and the Space Shuttle

The International Space Station
and the Space Shuttle
Updated November 3, 2008
Carl E. Behrens
Specialist in Energy Policy
Resources, Science, and Industry Division

The International Space Station and the Space Shuttle
Summary
The International Space Station (ISS) program began in 1993, with Russia
joining the United States, Europe, Japan, and Canada. Crews have occupied ISS on
a 4-6 month rotating basis since November 2000.
The U.S. Space Shuttle, which first flew in April 1981, has been the major
vehicle taking crews and cargo back and forth to ISS, but the shuttle system has
encountered difficulties since the Columbia disaster in 2003. Russian Soyuz
spacecraft are also used to take crews to and from ISS, and Russian Progress
spacecraft deliver cargo, but cannot return anything to Earth, since they are not
designed to survive reentry into the Earth’s atmosphere. A Soyuz is always attached
to the station as a lifeboat in case of an emergency.
President Bush, prompted in part by the Columbia tragedy, made a major space
policy address on January 14, 2004, directing NASA to focus its activities on
returning humans to the Moon and someday sending them to Mars. Included in this
“Vision for Space Exploration” is a plan to retire the space shuttle in 2010. The
President said the United States would fulfill its commitments to its space station
partners, and the shuttle Discovery made the first post-Columbia flight to the ISS in
July 2006. Shuttle flights have continued and completion of the space station is
scheduled before the shuttle is retired in 2010. Meanwhile NASA has begun
development of a new crew launch vehicle, named Ares, and a crew exploration
vehicle, named Orion.
NASA programs were funded for FY2008 in Division B of the Consolidated
Appropriations Act (P.L. 110-161). The Space Operations program, which includes
the space shuttle and the ISS, was funded at $6.734 billion. For FY2009 NASA
requested $5.775 billion for these programs, but in the process revised its budgeting
to move its overhead costs to a new account called Cross-Agency Support. Under
the new system, the FY2008 Space Operations program would have received $5.526
billion, about $250 million less than the FY2009 request. NASA is currently
operating under a continuing resolution (Division A of P.L. 110-329), which funded
most civilian activities through March 6, 2009. Under the continuing resolution,
Space Operations are funded at the $5.526 billion rate appropriated for FY2008.
An FY2009 NASA authorization bill (H.R. 6063) was introduced May 15, 2008.
Among the provisions in the one-year authorization bill was a “Sense of the
Congress” urging cooperation in the Moon/Mars activities with other nations
pursuing human space flight. It also requires that NASA “terminate or suspend any
activity of the Agency that, if continued between the date of enactment of this Act
and April 30, 2009, would preclude the continued safe and effective flight of the
Space Shuttle after fiscal year 2010 if the President inaugurated on January 20, 2009,
were to make a determination to delay the Space Shuttle’s scheduled retirement.”
Congress passed the bill September 27, and it was signed by the President October

15 (P.L. 110-422).

Contents
Most Recent Developments..........................................1
The International Space Station (ISS)..................................1
ISS Design, Cost, Schedule, and Lifetime...........................2
Space Station Costs........................................3
The Space Shuttle.................................................6
The Challenger and Columbia Tragedies.......................6
Return to Flight (RTF)......................................6
The Shuttle’s Future........................................7
Shuttle Budget............................................7
Issues for Congress................................................8
List of Tables
Table 1. U.S. Space Station Funding...................................5

The International Space Station and the
Space Shuttle
Most Recent Developments
With nine more flights to the International Space Station scheduled before the
space shuttle program is shut down in 2010, the shuttle Endeavour was poised to
launch November 12, 2008. In the meantime, the flight of the shuttle Atlantis to
service the Hubble Space Telescope, which had been planned for October, was
postponed until May or June 2009.
NASA programs were funded for FY2008 in Division B of the Consolidated
Appropriations Act (P.L. 110-161). The Space Operations program, which includes
the space shuttle and the ISS, was funded at $6.734 billion. For FY2009 NASA
requested $5.775 billion for these programs, but in the process revised its budgeting
to move its overhead costs to a new account called Cross-Agency Support. Under
the new system, the FY2008 Space Operations program would have received $5.526
billion, about $250 million less than the FY2009 request. NASA is currently
operating under a continuing resolution (Division A of P.L. 110-329), which funded
most civilian activities through March 6, 2009. Under the continuing resolution,
Space Operations are funded at the $5.526 billion rate appropriated for FY2008.
The International Space Station (ISS)
NASA launched its first space station, Skylab, in 1973. Three crews were sent
to live and work there in 1973-1974. It remained in orbit, unoccupied, until it
reentered Earth’s atmosphere in July 1979, disintegrating over Australia and the
Indian Ocean. Skylab was never intended to be permanently occupied, but the goal
of a permanently occupied space station with crews rotating on a regular basis,
employing a reusable space transportation system (the space shuttle) was high on
NASA’s list for the post-Apollo years following the moon landings. Budget
constraints forced NASA to choose to build the space shuttle first. The first launch
of the shuttle was in April 1981. When NASA declared the shuttle “operational” in

1982, it was ready to initiate the space station program.

In his January 25, 1984 State of the Union address, President Reagan directed
NASA to develop a permanently occupied space station within a decade, and to
invite other countries to join. On July 20, 1989, the 20th anniversary of the first
Apollo landing on the Moon, President George H. W. Bush voiced his support for the
space station as the cornerstone of a long-range civilian space program eventually
leading to bases on the Moon and Mars. That “Moon/Mars” program, the Space
Exploration Initiative, was not greeted with enthusiasm in Congress, primarily due

to budget concerns, and ended in FY1993, although the space station program
continued.
President Clinton dramatically changed the character of the space station
program in 1993 by adding Russia as a partner to this already international endeavor.
That decision made the space station part of the U.S. foreign policy agenda to
encourage Russia to abide by agreements to stop the proliferation of ballistic missile
technology, and to support Russia economically and politically as it transitioned from
the Soviet era. The Clinton Administration strongly supported the space station
within certain budget limits.
The International Space Station program thus began in 1993, with Russia
joining the United States, Europe, Japan, and Canada. An Intergovernmental
Agreement (IGA) established three phases of space station cooperation. The IGA is
a treaty in all the countries except the United States, where it is an Executive
Agreement. It is implemented through Memoranda of Understanding (MOUs)
between NASA and its counterpart agencies.
During Phase I (1995-1998), seven U.S. astronauts remained on Russia’s space
station Mir for long duration (several month) missions with Russian cosmonauts,
Russian cosmonauts flew on the U.S. space shuttle seven times, and nine space
shuttle missions docked with Mir to exchange crews and deliver supplies. Repeated
system failures and two life-threatening emergencies on Mir in 1997 raised questions
about whether NASA should leave more astronauts on Mir, but NASA decided Mir
was sufficiently safe to continue the program. (Mir was deorbited in 2001.) Phases
II and III involve construction of the International Space Station itself, and blend into
each other. Phase II began in 1998 and was completed in July 2001; Phase III is
underway.
President George W. Bush, prompted in part by the February 2003 space shuttle
Columbia tragedy, made a major space policy address on January 14, 2004, directing
NASA to focus its activities on returning humans to the Moon and eventually
sending them to Mars. Included in this “Vision for Space Exploration” was a decision
to retire the space shuttle in 2010. The President said the United States would fulfill
its commitments to its space station partners.
ISS Design, Cost, Schedule, and Lifetime
Under the original ISS schedule, assembly of the station would have been
completed in 2002, with operations at least through 2012. President Bush
restructured the space station program in 2001, and left it unclear when assembly
would be completed. NASA briefing charts in March 2003 showed space station
operations possibly continuing until 2022. Under President Bush’s January 2004
“Vision for Space Exploration,” however, NASA plans to complete its utilization of
ISS in 2016 (though the other partners may continue to use it after that time).
ISS segments have been and continue to be launched into space on U.S. or
Russian launch vehicles and assembled in orbit. The space station is composed of
a multitude of modules, solar arrays to generate electricity, remote manipulator

systems, and other elements. (Details can be found at [http://spaceflight.nasa.gov/
home/index .html].)
The U.S. space shuttle has been the major vehicle taking crews and cargo back
and forth to ISS, but the shuttle system encountered difficulties after the Columbia
disaster and did not resume flights until 2006. Russian Soyuz spacecraft are also
used to take crews to and from ISS, and Russian Progress spacecraft deliver cargo,
but cannot return anything to Earth, since it is not designed to survive reentry into the
Earth’s atmosphere. A Soyuz is always attached to the station as a lifeboat in case
of an emergency.
“Expedition” crews have occupied ISS on a 4-6 month rotating basis since
November 2000. Originally the crews had three members (two Russians and one
American, or two Americans and one Russian). Crew size was temporarily reduced
to two (one American, one Russian) while the U.S. shuttle was grounded in order to
reduce resupply requirements. The number of astronauts who can live on the space
station is limited in part by how many can be returned to Earth in an emergency by
lifeboats docked to the station. Only Russian Soyuz spacecraft are available as
lifeboats. Each Soyuz can hold three people, limiting crew size to three if only one
Soyuz is attached. The plan is that crew size will grow to six once assembly is
completed. The flight of the shuttle Endeavour, scheduled for November 2008, is
aimed at beginning preparations for a six-person crew.
Each Soyuz must be replaced every six months. The replacement missions are
called “taxi” flights since the crews bring a new Soyuz up to ISS and bring the old
one back to Earth. Therefore, under normal conditions, the long duration Expedition
crews are regularly visited by taxi crews, and by the space shuttle bringing up
additional ISS segments or exchanging Expedition crews. When the shuttle is
unavailable, Expedition crews are taken back and forth on the “taxi” flights.
In order to contract for Soyuz service to the ISS, NASA has needed an
exemption from the Iran Nonproliferation Act (INA) (P.L. 106-178), which banned
U.S. payments to Russia in connection with the International Space Station (ISS)
unless the U.S. President determined that Russia was taking steps to halt proliferation
of nuclear weapons and missile technology to Iran. In 2005 Congress amended INA
to exempt Soyuz flights to the ISS from the ban through 2011. It also extended the
provisions of the INA to Syria and North Korea, and renamed it the Iran, North
Korea, and Syria Nonproliferation Act (INKSNA). NASA asked for a legislated
extension of this exemption, and waiver authority was extended until July 1, 2016,
in the Continuing Appropriations Act of 2009 (P.L. 110-329). (For details see CRS
Report RL34477, Extending NASA’s Exemption from the Iran, North Korea, and
Syria Nonproliferation Act, by Carl Behrens and Mary Beth Nikitin.)
Space Station Costs. From FY1994 to FY2001, the cost estimate for
building ISS grew from $17.4 billion to about $25 billion. The $17.4 billion estimate
did not include launch costs, operational costs after completion of assembly, civil
service costs, or other costs. NASA estimated the program’s life-cycle cost (all costs,
including funding spent prior to 1993) from FY1985 toFY2012 at $72.3 billion. In

1998, GAO estimated the life-cycle cost at $95.6 billion (GAO/NSIAD-98-147).

More recent, comparable, life-cycle estimates are not available from NASA or GAO.

As costs continued to rise, Congress voted to legislate a $25 billion cap on
development of the ISS program, plus $17.7 billion for associated shuttle launches,
in the FY2000-FY2002 NASA authorization act (P.L. 106-391). In January 2001,
however, NASA announced that the cost would be over $30 billion, 72% above the
1993 estimate, and $5 billion above the legislated cap. NASA explained that
program managers had underestimated the complexity of building and operating the
station. The Bush Administration signaled it supported the legislated cap, would not
provide additional funds, and NASA would have to find what it needed from within
its Human Space Flight account.
“Core Complete” Configuration. In February 2001, the Bush
Administration announced it would cancel or defer some ISS hardware to stay within
the cap and control space station costs. The decision truncated construction of the
space station at a stage the Administration called “core complete.” In 2001, the space
station program office at Johnson Space Center (JSC) estimated that it would cost
$8.3 billion from FY2002 toFY2006 to build the core complete configuration,
described at that time as all the U.S. hardware planned for launch through “Node 2,”
plus the launch of laboratories being built by Europe and Japan. NASA subsequently
began distinguishing between “U.S. Core Complete” (the launches through Node 2,
which, prior to the Columbia tragedy, was scheduled for February 2004) and
“International Partner (IP) Core Complete” which included the addition of European
and Japanese laboratory modules (then anticipated in 2008).
The new policy was followed by President Bush’s January 2004 “Vision for
Space Exploration,” which directs that U.S. research on ISS be restricted only to that
which supports the Vision. A new research plan, incorporating the President’s
Vision, was issued by NASA in June 2006, as mandated by the 2005 NASA
authorization act (P.L. 109-155).¹
At a January 2005 Heads of Agency meeting, the partners endorsed a final
configuration of ISS, but NASA subsequently announced changes to it. The agency
now plans to conduct only 16 (instead of 28) shuttle launches to the ISS, all before
the end of FY2010 (September 30, 2010), and has dropped plans to launch the
centrifuge and its accommodation module, and Russia’s Science Power Platform.
The agency plans to meet with the other ISS partners to discuss these changes.
The changes to the ISS are largely due to the new direction NASA is taking in
response to the Vision for Space Exploration. The Vision calls for development of
a Crew Exploration Vehicle, now named Orion, to take astronauts to and from the
Moon, and a Crew Launch Vehicle, now named Ares I. Orion also can take them to
and from the ISS, and NASA Administrator Griffin stated at a September 19, 2005
press conference that Orion would be used to take crews to and from the ISS, and to
serve as a lifeboat for them. If Orion is built as announced, it would fulfill the U.S.

¹ The National Aeronautics and Space Administration (NASA).Research and Utilization
Plan for the International Space Station (ISS) A Report to the Committee on Science of the
United States House of Representatives and the Committee on Commerce, Science, and
Transportation of the United States Senate. June 2006. [http://www.exploration.nasa.gov/
documents/reports/NASA_Researc h_and_Utilization_Plan_for_the_ISS.pdf]

commitment to build a crew return capability, and allow the ISS crew size to increase
to its originally planned complement of seven. An Earth-orbit capability is planned
by 2014 (although NASA now considers early 2015 more likely) with the ability to
take astronauts to and from the Moon following no later than 2020.
Table 1. U.S. Space Station Funding
(in $ millions)
Fiscal YearRequestAppropriated
1985150150
1986230205
1987410410
1988767425
1989967900
19902,0501,750
19912,4301,900
19922,0292,029
19932,2502,100
19942,1062,106
19952,1132,113
19962,1152,144
19972,1492,149

1998 2,121 2,441^a

19992,2702,270
20002,4832,323
20012,1152,115
20022,114 2,093
20031,8391,810
2004^b 2,285 2,085
20052,4122,058
20061,9951,972

2007 1,894 NA^c

20081,8942,209

2009 2,060^d

^No^te:^T^h^es^{e n}^u^m^bers^ref^l^{ect NA}^SA^’^s^fⁱ^g^u^r^es^f^o^r^“^t^h^e^s^p^ace^s^t^ation^prog^ram^.^”^Ov^{er th}^{e y}^ears^,^w^h^at
^{is in}^clu^d^edⁱⁿ^th^{at d}^e^fⁱⁿ^itioⁿ^h^a^s^ch^an^g^e^d^.^In^recen^{t y}^{ears, f}^uⁿ^dⁱⁿ^g^f^o^{r ISS research}^h^a^{s b}^een^lo^cated
ⁱⁿ^a^dif^f^e^ren^t^accouⁿ^t^f^r^om^{ISS dev}^e^lopm^en^{t f}^uⁿ^dⁱⁿ^g^.^T^h^{e f}ⁱ^g^u^r^es^h^e^{re repres}^en^t^th^e^ISS^dev^e^lopm^en^t
^an^{d ISS res}^earch^requ^es^{t an}^{d appropriation}^s^{to th}^{e m}^a^xⁱ^m^u^m^ex^ten^t^pos^sⁱ^ble.
^{a. NA}^SA^’^s^{FY1999 bu}^dg^{et docu}^m^en^ts^s^h^ow^{ed $2.501 billion}ⁱⁿ^th^{e ex}^pecta^tion^C^oⁿ^g^r^es^s^w^o^u^l^d
^ap^p^r^o^v^{e ad}^d^itioⁿ^a^{l tr}^an^sf^er^r^e^q^u^{ests, b}^u^{t it d}ⁱ^dⁿ^o^t.
^{b. R}^e^f^l^ects^s^h^if^{t to f}^u^{ll cos}^t^accouⁿ^tin^g^.
^{c. Space s}^h^u^{ttle f}^uⁿ^dⁱⁿ^g^w^a^sⁿ^o^{t s}^p^ecifⁱ^{ed in}^P^.^L^.^110-^5.
^{d. R}^e^f^l^ects^ch^an^g^eⁱⁿ^bu^dg^etin^g^f^o^{r ov}^erh^{ead cos}^t^s^.

The Space Shuttle
The Space Transportation System (STS) — the Space Shuttle — is a partially
reusable launch vehicle and is the sole U.S. means for launching humans into orbit.
It consists of an airplane-like Orbiter, with two Solid Rocket Boosters (SRBs) on
each side, and a large, cylindrical External Tank (ET) that carries fuel for the
Orbiter’s main engines. The Orbiters and SRBs are reused; the ET is not. NASA has
three remaining spaceflight-worthy Orbiters: Discovery, Atlantis, and Endeavour.
The Challenger and Columbia Tragedies. More than 100 shuttle
launches have taken place since April 1981. Two ended in tragedy, each killing
seven astronauts. In 1986, the space shuttle Challenger exploded 73 seconds after
launch because of the failure of a seal (an O-ring) between two segments of an SRB.
In 2003, the space shuttle Columbia disintegrated as it returned to Earth after 16 days
in orbit (see CRS Report RS21408, NASA’s Space Shuttle Program: The Columbia
Tragedy, the Discovery Mission, and the Future of the Shuttle, by Marcia S. Smith).
A hole in Columbia’s left wing, caused during launch by a piece of foam insulation
that detached from the ET, allowed hot gases to enter the wing during reentry,
deforming it and causing the shuttle to break up. The Columbia Accident
Investigation Board (CAIB) found that the tragedy was caused by technical and
organizational failures, and made 29 recommendations, 15 of which it said should
be completed before the shuttle returned to flight.²
Sean O’Keefe, NASA’s Administrator from December 2001-February 2005,
said NASA would comply with the CAIB recommendations.
Return to Flight (RTF). NASA launched the space shuttle Discovery on the
first of two “Return to Flight” (RTF) missions — STS-114 — on July 26, 2005, and
it successfully landed on August 9. On July 27, however, NASA announced that a
piece of foam had detached from STS-114’s ET during launch, similar to what
happened to Columbia. Cameras and other sensors on Discovery and on the
International Space Station — to which Discovery was docked for much of its
mission — imaged the Orbiter and determined that it was not damaged, but further
shuttle launches were suspended. Meanwhile, the images revealed that two
“gapfillers” — ceramic coated fabric placed between thermal protection tiles — were
protruding on the belly of the Orbiter that could have affected aerodynamic heating
during reentry. One of the Discovery astronauts removed them during a space walk.
The second RTF mission — STS-121 — was scheduled for September 2005, but
deferred.
STS-121 launched on July 4, 2006, and returned safely to Earth on July 17. The
shuttle Atlantis launched September 9 on STS 115, during which construction of the
International Space Station was resumed.

² National Aeronautics and Space Administration. Columbia Accident Investigation Board
Report. August 2003. See CRS Report RS21606, NASA’s Space Shuttle Columbia: Synopsis
of the Report of the Columbia Accident Investigation Board, by Marcia S. Smith.

Current plans for the shuttle include nine more flights to complete the ISS
before the shuttle is permanently grounded in 2010. Also planned is another flight
to service the Hubble Space Telescope. Following the Columbia disaster, then-
Administrator Sean O’Keefe had cancelled the Hubble servicing mission, partly on
the grounds that shuttle astronauts would not be able to reach the ISS as a haven in
case the shuttle was unable to return to earth. The decision was put under review by
the new Administrator, Michael Griffin, and on October 31, 2006, he announced that
the Hubble mission would be undertaken in 2008. The servicing would extend the
life of the telescope through 2013. To deal with emergencies, NASA planned to
prepare a “launch on need” mission with a second shuttle ready to launch on a rescue
mission if the first was found defective during the servicing mission.
The launch was in final stages of preparation when a major data handling unit
already in place in the Hubble telescope failed in late September 2008. A backup
unit in the telescope was activated, but the service mission was revised to include
carrying a second data handling unit, which had been stored on earth, to replace the
failed one. NASA determined that assessing and preparing the second unit for
installation and service would delay the mission until May or June of 2009.
The Shuttle’s Future. NASA attempted unsuccessfully for many years to
develop a “second generation” reusable launch vehicle (RLV) to replace the shuttle.
In 2002 NASA indicated the shuttle would continue flying until at least 2015, and
perhaps 2020 or beyond. The Columbia tragedy, and President Bush’s 2004 Vision
for Space Exploration — to return astronauts to the Moon by 2020 and someday send
them to Mars — forced NASA to revise that plan.
The President’s Vision calls for the shuttle program, which absorbs
approximately 25% of NASA’s annual budget, to be terminated in 2010. A primary
motivation is to make that funding available to implement other aspects of the
Vision, although there also is concern about shuttle safety. Congress has been
debating the Vision, including its impact on the shuttle and on U.S. human access to
space. Some Members wanted to terminate the shuttle earlier than 2010 because they
feel it is too risky and/or that the funds should be spent on accelerating the Vision.
Others want to retain the shuttle at least until a new spacecraft, the Crew Exploration
Vehicle (CEV), is available to take astronauts to and from the ISS. The CEV is now
planned for 2015 at the earliest, leaving a multi-year gap during which U.S.
astronauts would have to rely on Russia for access to the ISS.
The 2008 NASA Authorization Act (P.L. 110-422) included a provision
requiring NASA to “terminate or suspend any activity of the Agency that, if
continued between the date of enactment of this Act and April 30, 2009, would
preclude the continued safe and effective flight of the Space Shuttle after fiscal year
2010 if the President inaugurated on January 20, 2009, were to make a determination
to delay the Space Shuttle’s scheduled retirement.” (Sec. 611d.)
Shuttle Budget. Funding for the shuttle for FY2008 was $3.981 billion. For
FY2009, NASA requested $2.982 billion for the shuttle, but that amount reflects
NASA’s new system for funding program overhead costs, which created a new
Cross-Agency Support account. By the new accounting system, the comparable
shuttle funding for FY2008 was $3.267 billion. (For details on the NASA budget,

see CRS Report RS22818, National Aeronautics and Space Administration:
Overview, FY2009 Budget, and Issues for Congress, by Daniel Morgan and Carl E.
Behrens.)
Issues for Congress
In passing the 2005 NASA authorization act (P.L. 109-105), Congress basically
agreed with the President’s plan for directing NASA’s attention to a return to the
Moon and manned missions to Mars. Included in the Moon-Mars “Vision” is the
plan to end flights of the Space Shuttle in 2010, and restriction of U.S. experiments
on the ISS mostly to those that forward the goal Moon-Mars goal. A number of
critical questions remain, however.
^!Adequacy of funding is the chief question raised about NASA’s
activities. In presenting the Moon-Mars vision, the President did not
request significantly increased money for NASA, despite chronic
indications that the missions it was already charged with were
underfunded. NASA has responded to the new mission by cutting
back funding for its other activities, primarily in scientific research
and aeronautics.
^!Although Discovery’s “Return to Flight” mission of July 2006 was
a success, the ability of the shuttle fleet to carry out enough flights
to complete construction of the ISS by 2010 is still in question.
With a history of more than a hundred successful missions, it might
be assumed that another 15 or so would be considered more or less
routine, but instead, each launch is still a major and risky event. The
great complexity of the vehicle and the extreme environment in
which it operates require constant attention to possible accidents and
malfunctions, many of which must be addressed on an ad hoc basis.
^!The future role of the ISS is also unclear. Assuming that enough
shuttle flights are made to carry out “core completion” of the station
by 2010, it is not clear what will be done with the ISS after that. In
particular, there will be a gap of several years between retirement of
the shuttle in 2010 and beginning of flight of the Crew Exploration
Vehicle, to be designed for the return to the moon but able to serve
as a vehicle to reach the ISS.