Order Code RL33568
The International Space Station
and the Space Shuttle
Updated May 29, 2008
Carl E. Behrens
Specialist in Energy Policy
Resources, Science, and Industry Division

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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.
A FY2009 NASA authorization bill (H.R. 6063) was introduced May 15, 2008.
Among the provisions in the one-year authorization bill is a “Sense of the Congress”
urging cooperation in the Moon/Mars activities with other nations pursuing human
space flight.

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Contents
Most Recent Developments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
The International Space Station (ISS) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
ISS Design, Cost, Schedule, and Lifetime . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Space Station Costs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
The Space Shuttle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
The Challenger and Columbia Tragedies . . . . . . . . . . . . . . . . . . . . . . . 6
Return to Flight (RTF) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
The United Space Alliance (USA) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
The Shuttle’s Future . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Shuttle Budget . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Issues for Congress . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
List of Tables
Table 1. U.S. Space Station Funding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

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The International Space Station and the
Space Shuttle
Most Recent Developments
In February 2008, the space shuttle Atlantis delivered Europe’s Columbus
laboratory module to the International Space Station (ISS). The mission continued
the sequence of shuttle flights to complete the ISS before the shuttle is retired in
2010.
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.
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.

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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” 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, but the details of how to accomplish that
without the shuttle were not announced.
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 are 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].) Six major
modules are now in orbit. The first two were launched in 1998: Zarya (“Sunrise,” a
Russian-built, U.S.-owned, module with guidance, navigation, and control systems)

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and Unity (a U.S. “node” connecting other modules). Next was Zvezda (“Star,” a
Russian module that serves as the crew’s living quarters) in 2000. Destiny (a U.S.
laboratory), Quest (a U.S. airlock), and Pirs (“Pier,” a Russian docking compartment)
arrived in 2001. Among the other modules awaiting launch are laboratory modules
built by Russia, Europe, and Japan, and two more “nodes” built by Europe. (Zarya
counts as a U.S. module because NASA paid Russia to build it. The European-built
nodes and Cupola count as U.S. components because they were built under barter
agreements where Europe produces hardware NASA needs instead of paying cash to
NASA for launch and other ISS-related services. Japan was to build a centrifuge and
its Centrifuge Accommodation Module under such a barter arrangement, but NASA
terminated that activity in 2005.)
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), with an expectation that crew size
would grow to six or seven once assembly was completed. 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. NASA planned to build a U.S. Crew Return
Vehicle (CRV) to provide lifeboat capabilities for at least four more crew. The Bush
Administration canceled those plans due to cost growth in the ISS program, then
began a different program (the Orbital Space Plane) that also was cancelled. In
September 2005, NASA announced that the new Crew Exploration Vehicle (CEV)
it is building to implement the President’s Vision for Space Exploration (the
“Moon/Mars” program) will be designed to take crews to and from the ISS, and to
serve as a lifeboat.
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

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to exempt Soyuz flights to the ISS from the Section 6 ban through 2011. It also
extended the provisions to Syria and North Korea, and renamed it the Iran, North
Korea, and Syria Nonproliferation Act (INKSNA). NASA has asked for a legislated
extension of this exemption. (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-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-FY2012 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-FY2006 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, has not been released by NASA. However, the 2005 NASA authorization act
(P.L. 109-155), directs that at least 15% of ISS research spending be non-Vision-
related (Sec. 204).
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

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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.
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 Year
Request
Appropriated
1985
150
150
1986
230
205
1987
410
410
1988
767
425
1989
967
900
1990
2,050
1,750
1991
2,430
1,900
1992
2,029
2,029
1993
2,250
2,100
1994
2,106
2,106
1995
2,113
2,113
1996
2,115
2,144
1997
2,149
2,149
1998
2,121
2,441 a
1999
2,270
2,270
2000
2,483
2,323
2001
2,115
2,115
2002
2,114 2,093
2003
1,839
1,810
2004 b
2,285
2,085
2005
2,412
2,058
2006
1,995
1,972
2007
1,894
NAc
2008
1,894
2,209
2009
2,060d

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Note: These numbers reflect NASA’s figures for “the space station program.” Over the years, what
is included in that definition has changed. In recent years, funding for ISS research has been located
in a different account from ISS development funding. The figures here represent the ISS development
and ISS research request and appropriations to the maximum extent possible.
a. NASA’s FY1999 budget documents showed $2.501 billion in the expectation Congress would
approve additional transfer requests, but it did not.
b. Reflects shift to full cost accounting.
c. Space shuttle funding was not specified in P.L. 110-5.
d. Reflects change in budgeting for overhead costs.
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. A total of 117 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.1
Sean O’Keefe, NASA’s Administrator from December 2001-February 2005,
said NASA would comply with the CAIB recommendations. He established an RTF
(“Return to Flight”) Task Group, chaired by two former astronauts, Tom Stafford and
Dick Covey, to oversee NASA’s implementation of the CAIB’s 15 RTF
recommendations. The Stafford/Covey Task Group [http://www.returntoflight.org]
did not address management and culture changes, and was not tasked to determine
whether the shuttle was ready to return to flight. Its assignment only was to evaluate
NASA’s compliance with the CAIB recommendations for RTF. The Task Group
ultimately concluded that NASA met the intent of 12 of the 15 CAIB RTF
recommendations, but not the other three: eliminating debris shedding from the
External Tank, hardening the Orbiter so it can better survive debris impacts, and
1 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.

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CRS-7
developing an on-orbit method of repairing the shuttle’s thermal protection system.
Michael Griffin, who became NASA Administrator in April 2005, said that NASA
and contractor personnel are those responsible and accountable for determining if and
when the shuttle is ready for RTF, and would not commit to meeting every CAIB
recommendation.
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. Atlantis returned to earth September 21.
Discovery was launched on STS 116 December 9 and returned 13 days later on
December 22. STS-117 was planned to launch in March 2007, but Atlantis, on the
launch pad in a late February hailstorm, was so damaged that it had to be returned to
the Vehicle Assembly Building for repairs. It launched successfully in June, and its
mission was followed by Endeavour in STS-118 in August, and by Discovery in
STS-120 in October. Atlantis is scheduled to fly STS-122 in December.
Current plans for the shuttle include 16 flights (including STS 121 and those
that have flown since) to complete the ISS before the shuttle is permanently grounded
in 2010. Also under consideration was 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, but the decision was put under review by the new Administrator, Michael
Griffin.
On October 31, 2006, NASA Administrator Griffin announced that the Hubble
mission would be undertaken in May 2008. The servicing would extend the life of
the telescope through 2013. To deal with emergencies, NASA plans to prepare a
“launch on need” mission with a second shuttle ready to launch on a rescue mission
if the first is found defective during the servicing mission.
The United Space Alliance (USA). In 1995, NASA decided to turn most
shuttle operations over to a “single prime contractor” — the United Space Alliance
(USA), a limited liability company owned 50-50 by Boeing and Lockheed Martin.
USA was created to pull together the 86 separate contracts with 56 different
companies under which the shuttle program was then operating. NASA officials

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assert that it has saved $1 billion a year compared to what the costs would have been
without it. NASA manages separate contracts with Lockheed Martin for the External
Tank, ATK Thiokol for the Solid Rocket Boosters, and Pratt & Whitney Rocketdyne
(owned by United Technologies) for the Space Shuttle Main Engines.
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 want 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 2012 at the earliest, leaving a multi-year gap during which U.S.
astronauts would have to rely on Russia for access to the ISS.
At the beginning of 2005, NASA officials indicated 28 shuttle flights were
needed to complete ISS construction. In the fall of 2005, NASA announced a new
plan showing 18 shuttle missions to the ISS, and possibly one more to service the
Hubble Space Telescope (see CRS Report RS21767, Hubble Space Telescope:
Should NASA Proceed with a Servicing Mission? by Daniel Morgan). As part of its
FY2007 budget request, NASA reduced to 16 the number of shuttle flights it now
plans to the ISS (plus one possible flight to Hubble). The two that were cut were
logistics flights taking cargo to the ISS. NASA is hoping that a commercial launch
service provider will develop vehicles that can perform that task. The original
versions of what became the 2005 NASA authorization act (P.L. 109-155) had
conflicting language about the future of the shuttle. The original Senate bill (S.
1281) directed NASA not to terminate the shuttle until a replacement was available;
the House version (H.R. 3070) directed NASA not to fly the shuttle after December
31, 2010. The final law states that it is U.S. policy to have human access to space on
a continuous basis, and directs NASA to submit several related reports to Congress.
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.)

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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. The current schedule is to fly the CEV
by 2012, but design of the vehicle is just beginning.

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