NASA: Challenges in Completing and Sustaining the International Space Station
Released: 2008-04-24T00:00:00

Letter

Background

The International Space Station program began in 1993 with several partner countries: Canada, the 11 member nations of the European Space Agency (ESA), Japan, and Russia. The ISS has served and is intended to expand its service as a laboratory for exploring basic questions in a variety of fields, including commercial, scientific, and engineering research. The first assembly flight of the station, in which the space shuttle Endeavor attached the U.S. laboratory module to the Russian laboratory module, occurred in early December of 1998. However, since the program’s inception, NASA has struggled with cost growth, schedule delays and re- designs of the station. As we reported in the past, these challenges were largely due to poorly defined requirements, changes in program content and inadequate program oversight. Due to these challenges, the configuration of the station has devolved over time. In the spring of 2001, NASA announced that it would make major changes in the final configuration of the ISS to address cost overruns. In 2003, the National Academies reported that this reconfiguration greatly affected the overall ability of the ISS to support science. NASA estimates that assembly and operating costs of the ISS will be between $2.1 billion to $2.4 billion annually for FY2009-FY2012. The ISS as of February 19, 2008, is approximately 65 percent complete.

The shuttle program and the ISS program are inherently intertwined. The shuttle has unique capabilities in that it can lift and return more cargo to and from orbit than any other current or planned space vehicle. Figure 1 shows the capabilities of the shuttle in various configurations. Most segments of ISS cannot be delivered by any other vehicle. For example, the Columbia disaster in 2003 put ISS assembly on hiatus as NASA ceased shuttle launches for 2½ years while it investigated the safety of the fleet. During this period, the Russian Soyuz became the means of transportation for crewmembers traveling to and returning from the ISS.

In a major space policy address on January 14, 2004, President Bush announced his “Vision for U.S. Space Exploration” (Vision) and directed NASA to focus its future human space exploration activities on a return to the Moon as prelude to future human missions to Mars and beyond. As part of the Vision, NASA is developing new crew and cargo vehicles, with the first crew vehicle currently scheduled to be available in 2015. The President also directed NASA to retire the space shuttle after completion of the ISS, which is planned for the end of the decade. Based on that directive, NASA officials told us that they developed a manifest consisting of 17 shuttle launches to support ISS assembly and supply between 2005 and 2010. Nine of these have taken place. In response to the President’s Vision, NASA formally set September 30, 2010, as the date that the shuttle program will cease because agency officials believe that continuing the program beyond that date will slow development of the agency’s new vehicles—specifically, the agency budget cannot support both programs at costs of $2.5 billion to $4 billion above current budget. As shown in Table 1, the shuttle program costs NASA several billion dollars annually and projected funding is phased out in fiscal year 2011. NASA officials stated that the majority of shuttle program cost is fixed at roughly $3 billion a year whether it flies or not. NASA officials stated that the average cost per flight is $150 million to $200 million.

The 2005 NASA Authorization Act designated the U.S segment of the ISS as a national laboratory and directed NASA to develop a plan to increase the utilization of the ISS by other federal entities and the private sector. In response, NASA has been pursuing relationships with these entities. NASA expects that as the nation’s newest national laboratory, the ISS will strengthen NASA’s relationships with other federal entities and private sector leaders in the pursuit of national priorities for the advancement of science, technology, engineering, and mathematics. The ISS National Laboratory is also intended to open new paths for the exploration and economic development of space.

The Retirement of the Shuttle Poses Challenges to NASA’s Ability to Complete the International Space Station

It will be a challenge for NASA to complete the space station by 2010 given the compressed nature of the schedule, maintenance and safety concerns, as well as events beyond its control such as weather. Any of these factors can cause delays that may require NASA to re-evaluate and reconstitute the assembly sequence. NASA remains confident that the current manifest can be accomplished within the given time and there are tradeoffs NASA can make in terms of what it can take up to support and sustain the station should unanticipated delays occur. However, failure to complete assembly as currently planned would further reduce the station’s ability to fulfill its research objectives and short the station of critical spare parts that only the shuttle can currently deliver.

Shuttle Flight Schedule Is Aggressive

In our July 2007 testimony, we reported that NASA planned to launch a shuttle once every 2.7 months. The plan for launches remains aggressive, partly because NASA plans on completing the ISS with the last assembly mission in April 2010, with two contingency flights in February and July 2010 to deliver key replacement units. The 5 months between the last assembly launch and shuttle retirement in September 2010 act as a schedule reserve, which can be used to address delays. There are 8 shuttle flights left to complete the station and two contingency flights left to deliver key components necessary to sustain the ISS after the retirement of the shuttle. There is an average of 2 ½ months between each shuttle launch. Table 2 shows the current shuttle manifest.

NASA has launched shuttles at this rate in the past. In fact, the agency launched a shuttle, on average, every two months from 1992 through the Columbia disaster in 2003. However, at that time the agency was launching a fleet of four shuttles. The shuttles require maintenance and refurbishing that can last four to five months before they can be re-launched. Launching at such a rate means that the rotation schedule can handle few significant delays, such as those previously experienced due to weather and fuel sensor difficulties. Lastly, NASA officials said that Shuttle Atlantis, which was to go out of service after the Hubble mission, will return to servicing the ISS for two more flights, which NASA believes will add more schedule flexibility.

Potential Launch Delays Remain

NASA officials stated repeatedly that NASA is committed to safely flying the shuttle until its retirement and will not succumb to schedule pressure. However, the compressed nature of the manifest will continue to test that commitment. Fuel sensor challenges continue to surface in the shuttle fleet. For example, the recent shuttle Atlantis launch was delayed two months while NASA addressed a fuel sensor problem associated with the shuttle’s liquid hydrogen tank. This is the same system that caused a 2- week delay in the launch of the shuttle Discovery in 2005.

There are also challenges associated with the shuttle launch window. NASA officials told us that the duration of that window is dependent on a number of factors, which include changes in the position of the earth and spacecraft traffic restrictions. NASA must consider its traffic model constraints for vehicles docking at the space station. According to the traffic model for ISS, no other vehicle can dock while the shuttle is docked, and each vehicle has constraints on how long it can stay docked. For example, the shuttle can dock for a maximum of 10 days, while the Soyuz can dock a maximum of 200 days. The docking of these two vehicles must be coordinated and meet other technical restrictions.

In addition, the shuttle has experienced delays due to severe weather, such as when Atlantis’s external tank was damaged by a hailstorm in 2007. In this case the delay was about three months. Figure 3 shows the delays in recent shuttle launches related to weather and other causes.

Completion of ISS Needed to Expand Scientific Research

The ISS is scheduled to support a six-person crew as early as 2009 and maintain that capability through 2016. NASA officials said that equipment essential to support a six-person crew, such as systems for oxygen recycling, removal of carbon dioxide and transforming urine into water as well as an exercise machine will be delivered to the station this fall. In addition, there are two components that have been planned to hold this and other equipment needed for the six-person crew, which are scheduled to go up in April 2010. If unanticipated delays occur, NASA may need to hold back these two components—known as the Node 3 and the Cupola— which could constrain the ability to conduct research and the quality of life on the station for the crew.

NASA officials emphasized that NASA’s intent was to have most science conducted on ISS only after the assembly of the ISS was completed. The ISS currently supports three crewmembers. NASA stated that the majority of the crew’s time is spent maintaining the station, rather than conducting scientific study. According to NASA, the crew spends no more than 3 hours per week on science. Completion of the ISS would allow NASA to expand to a six-person crew who could conduct more research.

Since the ISS is designated as a national laboratory, the expectation is that it will support scientific experimentation. NASA is in the process of negotiating agreements with scientific organizations to support scientific research on the ISS. NASA officials told us that they are negotiating a Memorandum of Understanding with the National Institutes of Health to explore the possibility of scientific experimentation onboard the ISS. These officials also told us that NASA is in the process of negotiating with at least two other agencies.

The Need to Pre-Position Replacement Units to Sustain the ISS May Also Affect Assembly

NASA’s efforts to complete the ISS are further complicated by the need to put replacement units—the spare parts that are essential to sustaining the ISS—into position before the shuttle retires. The two contingency flights of the shuttle have been designated to deliver these key replacement units, which only the shuttle is capable of carrying. According to NASA, the original approach to deal with these key components (also known as orbital replacement units—ORU) was to take the ones that failed or reached the end of their lifetime back to Earth on the shuttle, refurbish them and launch them back to ISS for use. As a result of the shuttle retirement, NASA will no longer be bringing down ORUs to fix. Instead, NASA officials stated they have adopted a “build and burn” philosophy, which means that after the shuttle retires, instead of being brought down to be refurbished, ORUs will be discarded and disintegrate upon re-entry into the atmosphere. To determine how many replacement units need to be positioned at the station, NASA officials told us they are using data modeling that has been very effective in determining how long ORUs will last. Table 3 illustrates the shuttle manifest. This includes elements needed for the planned configuration to complete the station and delivery of critical spares.

NASA currently plans to use two contingency flights for these replacements because all other flights are planned with assembly cargo. Recently, the NASA Administrator publicly stated that these flights are considered necessary to sustain the ISS and have been scheduled to carry key spare units.

Alternative Vehicle Options to Service the International Space Station Pose Challenges

In the event that NASA completes assembly of the ISS on schedule and prepositions an adequate number of critical spares, the agency still faces a myriad of challenges in sustaining the research facility until its retirement, currently planned for fiscal year 2016. Without the shuttle, NASA officials told us that they face a significant cargo supply shortfall and very limited crew rotation capabilities. NASA will rely on an assortment of vehicles in order to provide the necessary logistical support and crew rotation capabilities required by the station. Some of these vehicles are already supporting the station. Others are being developed by international partners, the commercial sector, and NASA. (See Figure 4) Furthermore, some of these transportation services may face legal restrictions, and still others face cost, schedule, and performance issues that raise serious questions about their development and utilization. These issues will challenge NASA’s ability to close the sustainment gap between the retirement of the shuttle in 2010 and the availability of the Crew Exploration Vehicle (CEV) in 2015. Failure of any or some of these efforts would also seriously restrict NASA’s options to sustain and maintain a viable space station.

Russian Vehicles

With the exception of the Shuttle and the recently completed demonstration flight of the ATV, the only vehicles currently capable of supporting the space station are the Russian Progress and Soyuz vehicles. NASA officials stated that both of these vehicles have provided reliable service to the ISS. From the Columbia disaster in 2003 until return to flight in 2005, the Russian vehicles were the sole source of logistical support and crew rotation capability for the station. The Progress provides atmospheric gas, propellant, water, and pressurized cargo. It also has the capability to use its thrusters to change the Station’s altitude and orientation. The Soyuz provides crew delivery and rescue capability for three crew members. Progress vehicles are expendable and offer no recoverable return capability, but provide important trash removal capabilities. Soyuz vehicles have a limited recoverable cargo capacity. However, some NASA officials have suggested that their limited capabilities restrict the capacity of the station to move to a six-member crew and significantly limit the scientific research because the vehicles cannot bring experiments to earth for assessment. NASA currently purchases crew and cargo transport services from Russia through a contract with the Russian Federal Space Agency (Roscosmos).

NASA officials told us that after the initial ISS contract between Roscosmos and NASA expired, NASA entered into another contract that runs through 2011. However, according to NASA, the Iran Nonproliferation Act of 2000 restricted certain payments in connection to the ISS that may be made to the Russian government. In 2005, NASA requested relief from the restrictions of the Act, and Congress amended the Act. Through this amendment, NASA and Roscosmos have negotiated quantities and prices for services through January 1, 2012.

NASA officials anticipate the use of 4 Soyuz flights per year and approximately 6 Progress flights beginning in approximately 2010. While NASA officials stated that they are making every effort to limit amount of fees they pay for usage of Russian vehicles, to date, NASA officials told us that they anticipate that from fiscal year 2009 to fiscal year 2012, NASA will spend $589 million on cargo and crew services from the Russians. NASA officials also told us that the Roscosmos has suggested that it will charge NASA higher fees for usage of its vehicles.

European and Japanese Vehicles

NASA has stated it will use its international partners’ vehicles to conduct some supply activities. Specifically, Japan’s Aerospace Exploration Agency (JAXA) H-II Transfer Vehicle (HTV) and the European Space Agency’s (ESA) Automated Transfer Vehicle (ATV) vehicles will be used for bringing up cargo. NASA’s reliance on the ATV and HTV assumes that these vehicles will be ready to service the ISS by the time the shuttle stops flying in 2010.

The new vehicles being developed by the European and Japanese space agencies are very complex. The ATV had a development timeline of 20 years. Its first operational test flight to the ISS was in March 2008. NASA has stated that both the European and Japanese vehicle development programs experienced technical hurdles and budgetary constraints, but are committed to fulfilling their roles as partners in the ISS program. NASA officials told us they have confidence the European vehicle will be available for ISS operations before retirement of the shuttle, but they are not as confident about the Japanese vehicle’s being ready by that time. The Japanese vehicle is still under development and has faced some setbacks. NASA officials told us that the HTV’s first test launch is planned for July 2009.

International Partner Vehicles Have Constraints in Ability to Ferry Crew and Cargo to and from the ISS in Comparison to the Shuttle

In addition to potential development challenges, the international partner vehicles have constraints in terms of what they can take to and from the ISS in comparison to the shuttle. NASA’s current plans to manage the gap after the shuttle retirement do not take into account the possibility of delays in the development of these vehicles, and even if they do come on line on time, NASA officials estimate that there will be a significant shortfall to the ISS of at least 114,199 pounds (or 51.8 metric tons) in cargo re-supply capability. These vehicles were designed to augment the capabilities of the shuttle and have significantly less capability to deliver cargo to the ISS. The shuttle can carry a maximum cargo of close to 38,000 pounds (17,175 kg.). In comparison, the European ATV’s maximum capability is 16,535 pounds (7,500 kg.) and the Japanese HTV’s average capability is 13,228 pounds (6,000 kg.). The HTV and ATV are expendable vehicles. NASA can use them for trash removal, but cannot carry cargo or scientific experiments back to earth because the vehicles disintegrate when re-entering the atmosphere.

The Russian Progress and Soyuz vehicles also have very limited cargo capacity. For example, the Progress has an average capability of 5,732 pounds (2,600 kg.)—roughly one-seventh the shuttle’s capability. The Progress, like the ATV and HTV, is an expendable vehicle. The Soyuz can transport three crew persons to the ISS and can serve as a rescue vehicle capable of taking three crew members back to earth. Unlike the ATV and HTV, the Soyuz does have the capacity to bring down cargo—roughly 132 pounds (60 kg.). NASA officials have stated that until NASA deploys its new crew exploration vehicles or commercial vehicles become available, NASA will be dependent on the Russian vehicles for crew transportation services and on the Japanese and European vehicles for limited cargo services whenever they become available.

Figure 7 compares the up mass capabilities of the various vehicles.

Commercial Vehicles

NASA is working with the commercial space sector through its Commercial Orbital Transportation Services (COTS) program to develop and produce vehicles that can take equipment and crew to and from the space station. NASA expects that these vehicles will be ready for cargo use in 2010 and crew use in 2012. However, these vehicles have yet to be successfully launched into orbit, and some NASA officials have acknowledged that their development schedules leave little room for the unexpected.

Under the COTS program, NASA has pledged $500 million to promote commercial opportunities for space transportation vehicles. Using Space Act agreements instead of traditional contracting mechanisms, NASA will make payments to companies based on the achievement of key milestones during the development of their vehicles. These agreements are both funded and unfunded. For the two funded agreements that have been reached, NASA stated that the commercial suppliers for space transportation services will have customers outside of ISS, including NASA’s Constellation program, which plans to send humans back to the moon and eventually Mars. The COTS program will occur in phases. In the first phase companies will demonstrate the vehicle launch and docking capabilities with the ISS. The second phase is the procurement of services for transportation of cargo and crew to the ISS, which is scheduled to begin sometime in the 2010 timeframe.

NASA had seven COTS agreements through the Space Act. NASA signed five unfunded Space Act agreements, which facilitate the sharing of technical and ISS integration information between commercial companies and NASA. NASA has funded two companies, Rocketplane Kistler (RpK) and Space Exploration Technologies (SpaceX). NASA officials stated that through the funded Space Act agreements, SpaceX has received $139 million for its project and is still working on successfully launching a vehicle that can reach low-Earth orbit. The company successfully completed a critical design review in August 2007 and told us that it is planning its first orbital demonstration test flight for June 2009. NASA officials told us that RpK received $37 million in funding, but then forfeited the remainder of its share because it did not meet certain financial development milestones. When NASA began to redistribute these forfeited funds, RpK filed a bid protest with GAO, which GAO denied. NASA officials then moved forward and awarded $170 million to Orbital Sciences Corporation in February 2008.

NASA officials acted quickly to award the forfeited money and expect that SpaceX will have cargo capability available in 2010 (by the time the shuttle is retired) and crew capability in 2012. While Space X has been meeting key milestones in the development of its vehicle, some officials at the Johnson Space Center were skeptical that COTS would be available on the current projected schedule. Additionally, the International Space Station Independent Safety Task Force (IISTF) reported that design, development and certification of the new COTS program was just beginning and that “if similar to other new program development activities, it most likely will take much longer than expected and will cost more than anticipated.” In our opinion, the schedule is optimistic when compared to other government and commercial space programs we have studied. We will be studying the COTS program and schedules in more detail in response to a request of members of congress.

Ares I and Orion

NASA is under pressure to develop its own vehicles quickly as the space shuttle’s retirement in 2010 means that there could be at least a 5-year gap in our nation’s ability to send humans to space. Among the first major items of NASA’s development efforts to implement the Vision program are the development of new space flight systems—including the Ares I Crew Launch Vehicle and the Orion Crew Exploration Vehicle. Ares I and Orion are currently targeted for operation no later than 2015. NASA plans to use these vehicles as they become available to service the space station.

However, we recently testified that there are considerable unknowns as to whether NASA’s plans for the Ares I and Orion vehicles can be executed within schedule goals, as well as what these efforts will ultimately cost. This is primarily because NASA is still in the process of defining many of the project’s performance requirements and some of these uncertainties could affect the mass, loads, and weight requirements for the vehicles. Such uncertainty has created knowledge gaps that are affecting many aspects of both projects. For example, a design analysis cycle completed in May 2007 revealed an unexpected increase in ascent loads (the physical strain on the spacecraft during launch) that could result in increases to the weight of the Orion vehicle and both stages of the Ares I.

NASA recognizes the risks involved with its approach and it is taking steps to mitigate those risks. However, given the complexity of the Orion and Ares I efforts and their interdependencies, any significant requirements changes can have reverberating effects and make it extremely difficult to establish firm cost estimates and schedule baselines. If knowledge gaps persist, programs will cost more, fail to meet their schedules, or deliver less than originally envisioned. Ultimately, NASA’s aggressive schedule leaves little room for the unexpected. If something goes wrong with the development of the Crew Launch Vehicle or the Crew Exploration Vehicle, the entire Constellation Program could be thrown off course and the return to human spaceflight further delayed.

Concluding Observations

The decision to retire the space shuttle in 2010 has had profound effects on the ISS program. It leaves little flexibility in the shuttle schedule. Any delays could require NASA to choose between completing the station as planned and the pre-positioning of needed critical spares. The decision also leaves NASA dependent on Russia for crew rotation services until other vehicles are developed and demonstrated. And even with the development of these vehicles, NASA still faces a significant capacity shortfall in its ability to provide logistical support to the station. The shortfall may well impact support for a six person crew and the quality of research that can be conducted on the ISS. At the same time, it also provides opportunities to commercial suppliers to demonstrate capabilities that could have long-term benefits for future U.S. space exploration and development. We are not making recommendations as a result of our review as NASA is well aware of the predicament it faces with the station and has weighed options and trade-offs for the remainder of the schedule manifest. However, it is important that flexibility continue to be maintained as events impacting schedule occur and that decisions be made with the goal of maximizing safety and results.

Mr. Chairman, this concludes my statement. I would be pleased to answer any questions that you or the other members may have at this time.

GAO Contacts and Staff Acknowledgments

For further questions about this statement, please contact Cristina T. Chaplain at (202) 512-4841. Individuals making key contributions to this statement include James L. Morrison, Greg Campbell, Brendan S. Culley, Masha P. Pastuhov-Purdie, Keo Vongvanith, and Alyssa B. Weir.

Appendix I: Scope and Methodology

To identify the risks and challenges NASA faces in completing assembly of the International Space Station by 2010, we analyzed key documents and testimonies by NASA officials relating to the challenges associated with ISS completion. This included: the delivery schedule for ISS parts for assembly and the delivery schedule for replacement units, the space shuttle manifest, budget documents and the strategic maintenance plan, the ISS Independent Safety Task Force Report, and previous GAO reports relating to the ISS. interviewed NASA mission officials to obtain information on the status of the ISS. We also discussed these issues with the International Partners (Canadian Space Agency, European Space Agency and Japan Aerospace Exploration Agency) to get their perspectives.

To determine the risks and challenges NASA faces in providing logistics and maintenance support to the International Space Station after 2010, we analyzed documents related to the up-mass and down-mass capabilities of the International Partners and SpaceX vehicles, the shortfall in ISS up- mass for re-supply and sustainment, the new vehicles that will support ISS NASA’s plans for using Russian vehicles to support ISS through what NASA refers to as its “exemption,” and the impacts to the utilization of the ISS.

We interviewed key NASA officials from NASA Headquarters, the Space Operations Mission Directorate, NASA’s Commercial Orbital Transportation Services program, and the ISS program officials, and interviewed officials representing the International Partners To accomplish our work, we visited and interviewed officials responsible for the ISS operations at NASA Headquarters, Washington, D.C., and the Johnson Space Center in Houston, Texas. At NASA Headquarters, we met with officials from the Exploration Systems Mission Directorate and the Space Operations Mission Directorate, including representatives from the International Space Station and space shuttle programs. We also met with ISS and space shuttle mission officials at the Johnson Space Center.

We conducted this performance audit from July 2007 to April 2008, in accordance with generally accepted government auditing standards. Those standards require that we plan and perform the audit to obtain sufficient, appropriate evidence to provide a reasonable basis for our findings and conclusions based on our audit objectives. We believe that the evidence obtained provides a reasonable basis for our findings and conclusions based on our audit objectives.

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