United States General Accounting Office

GAO Report to the Chairman, Subcommittee

on Oversight of Government

Management and the District of

Columbia, Committee on Governmental

Affairs, U.S. Senate

July 1995 SPACE SHUTTLE

Declining Budget and

Tight Schedule Could

Jeopardize Space

Station Support

GAO/NSIAD-95-171

GAO United States

General Accounting Office

Washington, D.C. 20548

National Security and

International Affairs Division

B-260359 

July 28, 1995

The Honorable William S. Cohen

Chairman, Subcommittee on Oversight

 of Government Management and the

 District of Columbia,

Committee on Governmental Affairs

United States Senate

Dear Mr. Chairman:

The National Aeronautics and Space Administration (NASA) plans to use

the space shuttle on 21 flights over a 5-year period to assemble the

International Space Station. To meet this requirement, the shuttle will have

to undergo substantial redesign to gain additional lift capability. As

requested, we examined the extent to which the shuttle program can

support the space station’s assembly requirements. In doing so, we

focused on the impacts of a declining shuttle budget and a demanding

schedule to support the space station.

Background The shuttle is the only U.S. launch vehicle capable of carrying humans into

space. As a result, it will be critical to the space station’s assembly and

operation. From December 1997 to June 2002, NASA plans to use the shuttle

primarily to transport station components into orbit for assembly. During

this period, 27 of the shuttle’s 34 primary payloads are to be

station-related.1

At times, only two of the four shuttles will be available for station

assembly. One shuttle—Columbia—cannot provide adequate lift, and, one

of the remaining three shuttles will be undergoing scheduled maintenance

during some portions of the assembly schedule. Also, most station

components will have to be launched in a particular sequence to provide

power and structural support for other hardware.

In March 1993, the President directed NASA to redesign the space station.

The new configuration—renamed the International Space

Station—combines the efforts of Europe, Japan, Canada, Russia, and the

United States. It also increased the station’s planned orbital inclination to

make it more accessible from Russian launch sites, creating the need for

1

NASA plans to use the shuttle for 21 space station assembly flights and 6 additional station-related

missions.

Page 1 GAO/NSIAD-95-171 Space Shuttle
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additional shuttle lift capacity. Easterly shuttle launches from Kennedy

Space Center take advantage of the earth’s normal west to east rotation.

Launches to higher inclinations such as those needed for the space station

lose some of this advantage, with a resulting loss in lift capability.

In November 1993, the space station program manager requested that the

space shuttle program implement modifications to provide the increased

lift needed to support space station assembly. The shuttle program office

responded by committing the program to increasing lift capability by at

least 13,000 pounds on every station flight.

Results in Brief NASA’s plans for increasing the shuttle’s lift capability are complex and

challenging, involving about 30 individual actions, including hardware

redesigns, improved navigational or flight design techniques, and new

operational procedures. Some of the hardware redesign programs have

experienced early development problems, and the potential exists for

additional problems according to one independent review team.

NASA’s schedule for meeting the space station’s launch requirements

appears questionable—particularly in a declining budget environment. To

support the first space station launch, NASA must successfully complete

numerous shuttle-related development programs on a tight schedule. The

remaining launch schedule is compressed and will be difficult to achieve

without additional funding or more efficient processing methods. Delays

in the launch schedule could substantially increase the station’s cost.

The shuttle’s modification and launch enhancement program includes

plans to defer some recertification activities and forgo full integration

testing of the propulsion system. As a result, shuttle modifications will be

fully integrated and flown for the first time on the first launch of station

components. NASA plans to assess the implications of the design changes

through a combination of tanking and component tests and systems

analyses. Given the magnitude and complexity of the shuttle enhancement

program, we believe it is prudent to take additional measures to ensure

that (1) the implications of integrating numerous individual design

changes are fully understood and (2) safety is not compromised.

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NASA’s Program to

Provide Added Lift Is

Complex and

Challenging

The lift enhancement plan—first approved in March 1994—has been

amended a number of times to introduce new ideas for achieving the

required lift at the least cost. The original plan identified 13,000 pounds of

added lift at a cost of about $535 million. In May 1995, NASA estimated that

about 16,100 pounds of lift gain would be achieved at a cost of about

$444 million. Both estimates included some recurring costs for

enhancement hardware, as well as costs to integrate the enhancements,

and reserves to cover the possible need for additional changes.

The current plan includes about 30 individual actions that involve

hardware redesign, improved navigational or flight design techniques, and

new operational procedures.2

 Figure 1 depicts the percentage of added lift

NASA estimates will come from these areas, based on the May 4, 1995,

approved baseline.

Figure 1: Actions to Increase Shuttle

Lift Capability Hardware redesign

Flight operations

Flight design

Other

58.1%

29.5%

10.2%

2.2%

Hardware design changes account for more than one-half of the added lift.

The primary redesign program is the development of a new external fuel

tank—the super lightweight tank—which involves incorporating a new

2

NASA defines hardware design as subsystem configuration. It defines flight design as the way the

vehicle is flown, and flight operations as the usage of consumables such as propellent and water.

Page 3 GAO/NSIAD-95-171 Space Shuttle
B-260359 

aluminum alloy into the tank design. This alloy will reduce the tank’s

weight and change its material properties. In addition, the tank will have

to accommodate a new set of design loads3

 created by the mix of

hardware and flight design changes. Other development programs

necessary to support the space station include various orbiter4

modifications and improved main engines.5

The super lightweight tank program has experienced some early

development problems that could affect its performance. Shortly after

beginning development of this tank, technical concerns about the

properties of the new material were raised. An independent review of the

program was performed, and based on its results, NASA adopted a more

rigorous test plan for the tank and modified the tank’s production strategy.

More recently, the uniqueness of the new metal caused delays in

manufacturing a test article. NASA believes these early concerns have been

resolved, but it recognizes that uncertainty with the development and

manufacturing of the new material could ultimately reduce the amount of

lift gain projected for the new tank.

The main engine improvements are expected to make the engines heavier

than the current engines. However, the new engines are expected to be

more efficient, thus needing less propellent. They are also expected to

permit occasional use at higher than normal thrust levels. Early test results

indicated that the engines would not achieve all of the efficiency originally

expected. NASA made additional modifications, and it now expects to

achieve most of the originally predicted performance. However, as of

May 1995, shuttle program officials still considered the engine

development status to represent a threat to the lift gain expected from the

enhancement program.

An independent shuttle management review team also expressed concerns

with these two programs. In its report,6

 the team (1) concluded that the

new tank had the potential for problems during development and

manufacturing and (2) questioned using the improved engines for

increased thrust capability.

3

Design loads are forces or pressures imposed on the shuttle during various parts of its mission such

as launch, ascent, and landing.

4

The shuttle system includes an aircraft portion—the orbiter—and propulsion components.

5

The main engine improvements are not included in the list of baselined enhancements since they were

initiated to improve safety margins. However, their availability for space station flights is required in

the overall strategy.

6

NASA, Report of the Space Shuttle Management Independent Review Team, February 1995.

Page 4 GAO/NSIAD-95-171 Space Shuttle
B-260359 

In addition to hardware redesign, NASA plans to incorporate flight design

and operation enhancements. These enhancements include the use of

more advanced navigational tools as well as software changes to create a

more efficient trajectory. The effect of achieving greater efficiency during

ascent is that less propellent would be needed.

The most significant operational change involves the deletion of some of

the contingency fuel, water, oxygen, and other consumables. NASA protects

each mission by ensuring that there are sufficient quantities of

consumables to continue the mission in the event of unexpected problems

such as difficulties in docking and retrieving payloads. In the past, it has

been NASA’s policy to cover nearly every possible contingency. The new

policy reduces the amount of consumables by about 4,000 pounds per

flight.

According to NASA, the revised approach will still ensure that individual

unexpected problems can be handled without jeopardizing the mission.

However, the reduction in consumables increases the risk of mission

failure if a combination of unexpected events occurs. Under the new

policy, for example, it might not be possible to perform a second

rendezvous with the station, if necessary, and, as a worst case, it could be

necessary to jettison a payload before landing.

NASA believes the increase in risk is minimal and cites the new policy as a

means to reduce weight, increase lift, and save money. In addition, it notes

that the maximum reduction in consumables will only be necessary on the

heaviest of station flights. According to the program director, this change

helped make it possible to terminate two of the more expensive

enhancements—development of a lightweight booster and extended motor

nozzle—at a savings of about $35 million.

To support the first shuttle space station launch, all of the enhancement

programs must be integrated and recertified into the shuttle system within

a demanding schedule. NASA has developed a systems integration plan

identifying the major events and schedules associated with the shuttle

enhancement program, as currently approved. The plan describes over 

200 individual events related to the development and integration of shuttle

lift-increasing modifications. The events began in early calendar year 1994,

and they will end with the first space station flight, which is scheduled for

December 1997.

Page 5 GAO/NSIAD-95-171 Space Shuttle
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The single most critical event is the delivery of the super lightweight tank,

and, according to the chief engineer of the shuttle integration office, it is

on a very success-oriented schedule that has already experienced some

delays. While the tank’s critical design review has already been held, the

final set of design loads are still being updated. Thus, many design and

environment definition activities will occur in parallel. If any of the

assumed design loads substantially change, additional certification cycles

may have to be conducted. However, there is no schedule or budget

margin that allows for major adjustments because the first tank is to be

delivered only 2 to 3 months before the first launch.

Shuttle’s Ability to

Support Station’s

Assembly Schedule Is

Questionable

Based on its launch history and projected budget, the shuttle may not be

able to meet the demanding launch requirements of the space station’s

assembly schedule. To meet the station’s “assembly complete” milestone,

shuttle officials have designed a very compressed launch schedule.

During certain periods of the station’s assembly, clusters of shuttle flights

are scheduled to be launched within very short time frames. The schedule

calls for five launches within a 6-month period in fiscal year 2000 and

seven flights during a 9-month period in fiscal year 2002. On two other

occasions, three launches are scheduled in a 3-month period. This

schedule equates to about 1 launch per month, or a rate of up to 

12 flights a year for these periods. In addition, on two occasions, the

schedule calls for launches of two missions with less than 35 days

separating them. While NASA has achieved similar launch rates a few times,

it will have fewer processing personnel during the space station era.

The space station’s flight rate frequency cannot be met unless the orbiter

is processed in 20 to 30 days less than standard.7

 To process the orbiter at

this rate, shuttle personnel will have to work overtime. However,

according to operations officials, budget constraints could make it difficult

to fund overtime.

Because the schedule is so compressed at times, there is very little margin

for error. According to shuttle and station officials, there is little flexibility

in the schedule to meet major contingencies, such as late delivery of

station hardware, or technical problems with the orbiters. Between

December 1991 and September 1994, 9 of 22 shuttle flights slipped from

the planned launch dates established 6 months before launch. The shuttle

7

According to Kennedy Space Center’s guidelines, standard processing for the orbiter is about 

127 calendar days—92 in the orbiter processing facility, 7 in the vehicle assembly building, and 28 on

the pad.

Page 6 GAO/NSIAD-95-171 Space Shuttle
B-260359 

program maintained its annual flight rate, in part, by launching payloads

out of sequence. However, during station assembly, most payloads must

be launched in the established sequence. The Shuttle Program Director

told us that he recognizes the launch schedule is tight and that if a

significant delay occurs with any station flight, subsequent flights are

likely to slip also.

The shuttle program will be attempting to accomplish the demanding

station assembly schedule with fewer resources than were available in the

past. For example, to reduce operating costs, NASA has reduced the shuttle

processing workforce at Kennedy Space Center by 1,400 people, or

20 percent, since 1992. According to a February 1995 internal workforce

review, schedule risk already exists in areas such as engine testing, crew

training, and flight software development, and NASA plans further funding

cuts in the future. According to shuttle processing officials, NASA will

reduce the shuttle processing workforce by another 900 people, or

15 percent, through fiscal year 2000. NASA continues to review all elements

of shuttle operations to improve processes and increase efficiency and

believes that these savings are achievable.

At the time of the fiscal year 1996 budget request, estimated shuttle

operations funding requirements exceeded projected budgets by at least

10 percent—a cumulative total of $1.3 billion—in fiscal years 1996 through

2000. Shuttle managers were concerned about their ability to achieve the

additional funding cuts needed to meet the projected budgets. In

February 1995, independent review teams recommended additional ways

to reduce shuttle operations costs. NASA does not have an estimate of

savings that may result from implementing the recommendations.

According to the Director of Shuttle Management and Operations at

Kennedy Space Center, the station’s assembly schedule will slip unless

(1) NASA provides additional funds for shuttle operations or (2) more

efficiencies are found.

Officials in the Office of Space Flight told us that they estimated that there

is a medium to high risk that the station’s assembly completion date will

slip because of shuttle delays. These officials estimated that the schedule

could slip about 4 to 5 months. Their estimate was based on the fact that

the shuttle achieved one less flight than planned in 2 of the past 4 years.

A recent internal NASA study acknowledges the possibility of a slip in the

schedule. According to the April 1995 study conducted for the

International Space Station Independent Assessment Office at Johnson

Page 7 GAO/NSIAD-95-171 Space Shuttle
B-260359 

Space Center, the shuttle cannot support the planned schedule unless

additional launch resources are provided or shuttle processing methods

are streamlined. The study identified a possible slip of up to 4 years in

completing station assembly due to shuttle processing delays and the

relatively low reliability of the Russian Zenit launch vehicle. According to

the study, shuttle processing presents the largest schedule risk. To meet

the manifest, NASA would have to reduce processing time to 50 percent of

current levels.

A delay in completing the space station assembly would increase the

station’s cost because fixed costs would be continued for a longer period.

No reliable estimate of the increased cost exists since the estimate would

depend on the length of the delay and assumptions about how long the

station would remain operational after assembly is complete. However,

when NASA redesigned the station in 1994, officials estimated the redesign

would reduce costs by $1.6 billion because it would accelerate the

assembly complete date by 15 months, from September 2003 to June 2002.

At a minimum, a portion of these savings would be lost if the assembly

complete date slips.

NASA Plans to Defer

Some Orbiter

Recertification

Activities and Forgo

System Testing

NASA plans to defer some orbiter recertification activities and forgo testing

all of the changes in an integrated fashion. NASA is confident that the

maturity of the current system and existing databases from earlier testing

are sufficient to justify the current approach.

To reduce costs, NASA plans to alter the depth of a previously planned

materials review. The review was to have been part of a program to

recertify the individual shuttle orbiters after incorporating the

performance enhancements for the space station program. It would have

provided specific and detailed assurance that every piece of the orbiter

structure could safely withstand the aerodynamic environments during

space station missions. The space station mission environments are

expected to be more stressing than those of previous missions. The

purpose of the materials review was to identify and reevaluate those

structural components that were previously accepted even though they did

not fully conform to design specifications.

NASA currently plans to assess the impact of the new environments on

these components based on the design rather than the actual hardware. A

materials review will be performed on critical structures, according to

NASA. NASA officials also told us that they are confident the streamlined

Page 8 GAO/NSIAD-95-171 Space Shuttle
B-260359 

recertification program will adequately ensure that the orbiter will

perform in all possible station era environments. They noted that the

orbiter now has a lengthy flight history record, and the experience gained

from those flights ensures that the design changes made to support the

space station will be fully understood.

In addition, NASA does not plan to perform test firings of the modified

propulsion system in an integrated setting. Instead, the agency plans to

verify system performance based on individual component testing and

predictive analyses. A 1989 study performed for the Stennis Space Center

addressed the concept of integrated system testing. The study cited the

unpredictability of the “interactive characteristics of the propulsion,

structural, and electrical systems” and concluded that propulsion system

testing should be considered even in cases of “existing designs modified to

accommodate one or more major system redesigns.” The same study

noted, however, that the technology base for the shuttle propulsion system

is more advanced than for other vehicles, thus mitigating the engineering

risks.

NASA does not believe integrated system test firings are necessary in this

case. Program officials noted that the propulsion system’s design changes

do not affect the way in which fluids and propellent are moved throughout

the system. As a result, they believe component testing, coupled with

inferential analysis and modeling of the whole system, will suffice. In

addition, program management officials stated that the costs were too

high to justify integrated test firings, given the test results and analyses

that would be available without integrated tests.

NASA Has Not

Chartered an

Independent Review

of Enhancement

Integration

Independent assessments provide objective overviews of complex

development programs and space missions and can create an incentive for

more rigorous internal review of the program. In establishing an

independent group to oversee space station program safety, for example,

NASA noted that “engineering products are improved by independent

technical peer review,” and that such reviews do not “reflect on the

competence, motivations, or integrity” of those responsible for

implementing a program. NASA’s recently completed laboratory review also

endorsed the concept of independent review in situations where the need

has been identified. The report, issued in February 1995, cited the value of

being in a position to take a more objective view of issues and details. It

also noted that the process of independent assessment requires managers

Page 9 GAO/NSIAD-95-171 Space Shuttle
B-260359 

to “review their efforts from a perspective that is hard to maintain in the

day-to-day sequence of events.”

In the past, NASA has sometimes chartered independent assessments of

complex development programs and missions, including assessments of

some parts of the performance enhancement program such as the main

engine improvement program and the super lightweight tank development.

However, NASA has not requested an independent assessment of the

integrated shuttle performance enhancement program, even though the

integration program is complex—consisting of over 200 scheduled events,

involving uncertainties such as characterization of the aerodynamic

environments the enhanced shuttle will operate in, and containing

departures from previous programmatic strategies.

Recommendation We recommend that the Administrator of NASA establish an independent

review team to (1) assess NASA’s systems integration plan for the

lift-increasing enhancements, (2) identify the associated technical and

programmatic risks, and (3) weigh the costs and benefits of NASA’s tight

scheduling of shuttle flights to assemble the space station.

Agency Comments In commenting on a draft of this report, NASA concurred with our

recommendation and stated that it had initiated implementation. The

Aerospace Safety Advisory Panel has agreed to perform the independent

reviews. According to NASA, the panel will use expert outside consultants

to review the benefits and the technical and scheduling risks considering

the current and projected NASA budgets. NASA noted that although the space

station assembly schedule was demanding and funding was tight, it was

currently on schedule and within budget. NASA’s comments are presented

in their entirety in appendix I, along with our evaluation of them.

Scope and

Methodology

We conducted our review at NASA Headquarters, Marshall Space Flight

Center, Johnson Space Center, and Kennedy Space Center. We examined

(1) shuttle enhancement documentation, (2) budgetary data, (3) internal

and external analyses regarding the shuttle program, (4) shuttle manifests,

(5) shuttle processing data, and (6) space station assembly schedules. In

addition, we interviewed officials from NASA Headquarters, the shuttle

program, and the space station program regarding issues related to NASA’s

plan to support space station assembly. These interviews included

Page 10 GAO/NSIAD-95-171 Space Shuttle
B-260359 

discussions with representatives of the Astronaut Office at Johnson Space

Center.

We performed our work between November 1994 and May 1995 in

accordance with generally accepted government auditing standards.

Unless you publicly announce the contents of this report earlier, we plan

no further distribution of it until 15 days from its issue date. At that time,

we will send copies of it to the Administrator, NASA; the Director, Office of

Management and Budget; and other appropriate congressional

committees. We will also provide copies to others upon request.

Please contact me on (202) 512-8412 if you or your staff have any

questions concerning this report. Major contributors to this report were

Lee Edwards, John Gilchrist, and Reginia Grider.

Sincerely yours,

David R. Warren

Director, Defense Management

 and NASA Issues

Page 11 GAO/NSIAD-95-171 Space Shuttle
Appendix I 

Comments From the National Aeronautics

and Space Administration

Note: GAO comments

supplementing those in the

report text appear at the

end of this appendix.

Page 12 GAO/NSIAD-95-171 Space Shuttle
Appendix I 

Comments From the National Aeronautics

and Space Administration

See comment 1.

Now on p. 2.

See comment 2.

Now on p. 2.

Now on p. 6.

Now on p. 7.

Now on p. 7.

Page 13 GAO/NSIAD-95-171 Space Shuttle
Appendix I 

Comments From the National Aeronautics

and Space Administration

Now on p. 7.

See comment 3.

Now on p. 10.

Page 14 GAO/NSIAD-95-171 Space Shuttle
Appendix I 

Comments From the National Aeronautics

and Space Administration

The following are our comments on the National Aeronautics and Space

Administration’s (NASA) letter dated June 23, 1995.

GAO Comments 1. We have incorporated NASA officials informal comments in the text

where appropriate.

2. Although the development programs have not experienced significant

schedule slips to date, the programs have experienced some early

development problems and an independent management review team

concluded in February 1995 that the largest of these programs—the super

lightweight tank—had the potential for further problems during

development and manufacture. As we note on page 5, NASA deleted two

expensive hardware programs by substituting operational changes that

substantially reduced weight but increased the risk of mission failure.

3. The April 1995 study was intended to identify the shuttle program’s

challenge in supporting the station assembly schedule and provide an

indication of the possible magnitude of schedule slips. Study officials told

us that the conversion from workdays to calendar days or use of available

overtime would not substantially change the study results. The study was

based on actual timelines experienced since the shuttle returned to flight

after the Challenger accident. NASA has not defined the streamlined

payload checkout and orbiter processing approaches that it says will be in

place beginning in 1998. The impact of streamlining on the shuttle’s launch

schedule cannot be determined at this time.

Subsequent to commenting on the report, officials ran the study model

again, using processing times for only those missions launched in fiscal

years 1992 and subsequent, and omitting the two flights with the longest

processing times. In this scenario, the model predicted a slip of over 1 year

in the station assembly complete milestone, assuming 100 percent

reliability and an inflexible assembly sequence.

(709056) Page 15 GAO/NSIAD-95-171 Space Shuttle
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