The Space Shuttle—Evaluating an American icon

The Space Transportation System (STS), for better or worse, has dominated the US space program for some 30 years and is now an American icon. The Space Shuttle orbiters have flown over 120 missions and certainly accomplished some amazing feats, including the deployment of the International Space Station (ISS), the launch and double repair of the Hubble Telescope, a number of classified missions for the US defense establishment and the cementing of international cooperation in space. As the remaining Space Shuttle orbiters head toward various museums, it is timely to look at the STS program in terms of key US space policy decisions that have paralleled the Space Shuttle’s often troubled history. This article seeks, from both a historical and a policy perspective, to assess what might have been. While noting the major accomplishments of the STS, it also identifies what can best be characterized as major lost opportunities and flawed policy decisions that have had multi-billion dollar consequences. In this regard, the US Congress, the White House, and NASA leadership have all played a role. If there have been failings, they have not been by NASA alone, but the entire US space policy leadership.     

Priorities in space for the USA

This article follows the story of Shuttle development, in the context of the history of the US space programme from Apollo to the Space Station. The Shuttle was chosen as one of a series of ‘space spectaculars’ and has proven to be prohibitively expensive and unreliable, practical only for a very limited number of specialized missions. The Space Station, too, cannot be economically supplied, even if the USA could afford to build it. The author concludes that NASA should cancel the Space Station and the replacement orbiter for Challenger, and engage on a major programme of launch vehicle development, independent of the US military. The aim should be a dramatic reduction of launch vehicle costs, making spaceflight practical, and a truly independent NASA which could restore the USA to space preeminence.     

Dynamics of the orbiter based construction of structural components for space platforms

A relatively general formulation for studying liberational dynamics of a large class of spacecraft during deployment of arbitrarily oriented beam and plate type flexible members has been developed by the authors. The formulation is applicable to a variety of missions ranging from deployment of antennas, booms and solar panels to manufacturing of trusses for space platforms using the Space Shuttle. The governing nonlinear, nonautonomous and coupled equations of motion are extremely difficult to solve even with the help of a computer, not to mention the cost involved. To get some appreciation as to the complex interaction between flexibility, deployment and attitude dynamics as well as to help pursue stability and control analyses, the procedure is applied to the Space Shuttle based deployment of plate-like members. Results suggest substantial influence of the flexural rigidity of the appendages, deployment velocity, initial conditions, and appendage orientation on the system response. Deployment maneuvers in conjunction with a typical controlled time history of permissible liberational rates suggest flexible plate members to be stable. In general, the instability is triggered through roll excitation leading to unbounded yaw due to coupling. The results should prove useful in planning of the Orbiter based experiments aimed at studying dynamics and control of flexible, deployable structural components needed in construction of space platforms.     

Risk management in international manned space program operations

New, innovative joint safety policies and requirements were developed in support of the Shuttle/Mir program, which is the first phase of the International Space Station program. This work has resulted in a joint multinational analysis culminating in joint certification for mission readiness. For these planning and development efforts, each nation's risk programs and individual safety practices had to be integrated into a comprehensive and compatible system that reflects the joint nature of the endeavor. This paper highlights the major incremental steps involved in planning and program integration during development of the Shuttle/Mir program. It traces the transition from early development to operational status and highlights the valuable lessons learned that apply to the International Space Station program (Phase 2). Also examined are external and extraneous factors that affected mission operations and the corresponding solutions to ensure safe and effective Shuttle/Mir missions.     

Orbital manoeuvres of free flying platforms for retrieval by space shuttle

In a typical future mission a free flying platform will be released to space by Space Shuttle. After performing its active mission, it will have to wait for a suitable later Shuttle flight for retrieval at its original orbital altitude. To allow for the orbital descent during the total mission time of typically several months, one or several orbit raise manoeuvres have to be performed with the platform's own propulsion system. In the paper, the velocity-requirements Δv for these orbital transfers, depending on Sun activity, rendezvous-altitude, ballistic coefficient and longest expected mission time are treated.The simplest manoeuvre, consisting of one initial ascent transfer and one descent transfer at the actual retrieval date, is shown to be not optimal. Up to 25% of Δv can be saved, if several orbit raising transfers in a certain sequence are applied. A straightforward analytical treatment is presented for the optimization, while a computer program with the CIRA-atmosphere model is used for actual mission planning.     

The shuttle development and its growth potential

During the next two decades, we will establish the foundation for the 21st century's accomplishments in space. The Space Shuttle vehicle will become the cornerstone for that foundation by providing economical opportunities for space exploration and utilization.Reusability of the Shuttle vehicle is the key to its economy. The major developmental challenges encountered in the Shuttle program are typified by the complexities involved in designing the reusable propulsion and thermal protection subsystems. We successfully met such challenges and are nearing the launch of the first Shuttle orbital flight.Our immediate goal is to enter the Space Shuttle operational phase because only then will we fully understand the unique capabilities of the Shuttle. Concurrent with our effort to begin Shuttle operations are our initial efforts to expand Shuttle capabilities, extending them significantly beyond those of the current baseline system.Shuttle payload capacity and mission-duration capabilities are to increase considerably during the next decade. Just as present Shuttle performance specifications and development timetables were guided by the space program plans and forecasts of the 1960s, so will the development of long-range space programs be determined by our near-future achievements. We anticipate that the Space Shuttle will play a critical role in those achievements.     

The origin of the smaller, faster, cheaper approach in NASA’s solar system exploration program

The current emphasis on smaller, faster, cheaper (SFC) spacecraft in NASA’s solar system exploration program is the product of a number of interacting – even interdependent – factors. The SFC concept as applied to NASA’s solar system exploration program can be viewed as the vector sum of (1) the space science community’s desire for more frequent planetary missions to plug the data gaps, educate the next generation of scientists, provide missions to targets of opportunity, and enable programmatic flexibility in times of budgetary crisis; (2) the poor publicity garnered by NASA in the early 1990s and the resultant atmosphere of public criticism (creating an opportunity for reform); (3) The Strategic Defense Initiative Organization’s and the National Space Council community’s desire to advance the Space Exploration Initiative and their perception that the NASA culture at the time represented a barrier to the effective pursuit of space exploration; (4) the effective leadership of NASA Administrator Daniel Goldin; and (5) the diminishing budget profile for space sciences in the early 1990s. This paper provides a summary of the origin of the smaller, faster, cheaper approach in the planetary program. A more through understanding of the history behind this policy will enable analysts to assess more accurately the relative successes and failures of NASA’s new approach to solar system exploration.     

Status and efficacy of countermeasures to physiological deconditioning from space flight

The recent biomedical investigations conducted on the Space Shuttle and Spacelab have provided a wealth of biomedical information, including the ability to test the efficacy of proposed countermeasures. This achievement was made possible by the ability to conduct mechanistic and control-interventive studies simultaneously with a large number of individuals over a relatively brief period and to compare these data with results obtained from the Skylab missions. Comparisons between short- and long-duration results were limited to establishing trends or extrapolating from short-duration missions. To date, we have evaluated several protocols involving the lower-body negative pressure (LBNP) device, the bicycle-ergometer, the treadmill and preparations for body-fluid replenishment. In many instances, the traditional means of applying these protocols were not sufficient to protect against space-related deconditioning. This paper will review current countermeasures and compare their efficacy to that of existing protocols. Results from in-flight and ground-based experiments will be presented to illuminate the recommended protocols and procedures.     

Shuttle demonstration of large space structure fabrication and assembly

The purpose of this paper is to describe a program aimed at an early on orbit demonstration of a large space structure fabrication and assembly capability. Requirements for the demonstration concept have been formulated. The concept that has been selected to meet these requirements is a Large Space Structure Platform consisting of a triangular prism of 31.5 m length. Sensors can be mounted on this platform to perform Earth observation measurements from space. Structural elements of the platform are fabricated using an automated beam builder in the Shuttle Orbiter payload bay. Special fixtures are designed to assemble the structure with the aid of the Remote Manipulator System and two astroworkers in an EVA mode. Results are shown of the platform preliminary design in terms of a design layout with related structural, thermal, mass properties and control dynamics data. The assembly scenario is described. Estimates of the total construction time and Orbiter support requirements are also presented.     

Orbit prediction and shuttle rendezvous strategy for eureca

The European Retrievable Carrier (EURECA) is a platform to be launched, deployed and retrieved in low Earth orbit by the Space Shuttle.A newly developed analytical orbit prediction method is described which meets the severe requirements for EURECA's orbit propagation. It is based on an averaging procedure including the Earth's zonal harmonics J₂, J₃ and J₄ and a refined treatment of the air drag perturbation where EURECA's large solar panels are taken into account. Some orbit prediction results are included.In order to offer more flexibility for the Shuttle retrieval of EURECA, it is proposed to execute a part of the rendezvous manoeuvres by EURECA. A corresponding strategy is described.     

Leadership issues with multicultural crews on the international space station: lessons learned from Shuttle/Mir

In isolated and confined environments, two important leadership roles have been identified: the task/instrumental role (which focuses on work goals and operational needs), and the supportive/expressive role (which focuses on morale goals and emotional needs). On the International Space Station, the mission commander should be familiar with both of these aspects of leadership. In previous research involving a 135-day Mir space station simulation in Moscow and a series of on-orbit Mir space station missions during the Shuttle/Mir program, both these leadership roles were studied. In new analyses of the Shuttle/Mir data, we found that for crewmembers, the supportive role of the commander (but not the task role) related positively with crew cohesion. For mission control personnel on the ground, both the task and supportive roles of their leader were related positively to mission control cohesion. The implications of these findings are discussed in terms of leadership on board the International Space Station.     

Preparing EMU for Space Station

In today's fiscally constrained environment, it can be expected that systems designed for one space program will increasingly be used to support other programs. The example of the U.S. extravehicular mobility unit (EMU), designed for use with the Space Shuttle, and now part of the baseline for the International Space Station (ISS) program, illustrates the adaption process. Certifying the Shuttle's EMU for use aboard ISS requires addressing three fundamental issues: Identifying new ISS requirements to be imposed on the EMU. Extending Shuttle's EMU on-orbit service interval to meet ISS's longer missions. Certifying Shuttle's EMU to meet new environments unique to ISS. Upon completion of the certification process, Shuttle's EMU will meet all requirements for supporting both the Shuttle and ISS program. This paper discusses the processes for addressing these issues and progress to date in achieving resolution.     

Using Spacelab as a precursor of science operations for the Space Station

For more than 15 years, Spacelab, has provided a laboratory in space for an international array of experiments, facilities, and experimenters. In addition to continuing this important work, Spacelab is now serving as a crucial stepping-stone to the improved science, improved operations, and rapid access to space that will characterize International Space Station. In the Space Station era, science operations will depend primarily on distributed/remote operations that will allow investigators to direct science activities from their universities, facilities, or home bases. Spacelab missions are a crucial part of preparing for these activities, having been used to test, prove, and refine remote operations over several missions. The knowledge gained from preparing these Missions is also playing a crucial role in reducing the time required to put an experiment into orbit, from revolutionizing the processes involved to testing the hardware needed for these more advanced operations. This paper discusses the role of the Spacelab program and the NASA Marshall Space Flight Center- (MSFC-) managed missions in developing and refining remote operations, new hardware and facilities for use on Space Station, and procedures that dramatically reduce preparation time for flight.     

The US–Europe technology gap in space transportation: the view from the USA

This paper examines the debate within the USA over how to meet the perceived competition from the successful European Ariane launcher and the loss of US market share for space launch services that it represented. In particular, it explores the origins of the 1983 Reagan Administration policy to turn over expendable launch vehicle production and operation to private industry. The Administration's other decisions to: (1) use the Space Shuttle to fly all government payloads, and (2) allow NASA to market Space Shuttle services commercially, conflicted with this commercialization policy. These policies effectively caused US industry to delay entry into the international competition for launch services until after the loss of the Space Shuttle Challenger in January 1986.     

The future of human spaceflight.

After the Apollo Moon program, the international space station represents a further milestone of humankind in space, International follow-on programs like a manned return to the Moon and a first manned Mars Mission can be considered as the next logical step. More and more attention is also paid to the topic of future space tourism in Earth orbit, which is currently under investigation in the USA, Japan and Europe due to its multibillion dollar market potential and high acceptance in society. The wide variety of experience, gained within the space station program, should be used in order to achieve time and cost savings for future manned programs. Different strategies and roadmaps are investigated for space tourism and human missions to the Moon and Mars, based on a comprehensive systems analysis approach. By using DLR's software tool FAST (Fast Assessment of Space Technologies), different scenarios will be defined, optimised and finally evaluated with respect to mission architecture, required technologies, total costs and program duration. This includes trajectory analysis, spacecraft design on subsystem level, operations and life cycle cost analysis. For space tourism, an expected evolutionary roadmap will be described which is initiated by short suborbital tourism and ends with visionary designs like the Space Hotel Berlin and the Space Hotel Europe concept. Furthermore the potential space tourism market, its economic meaning as well as the expected range of the costs of a space ticket (e.g. $50,000 for a suborbital flight) will be analysed and quantified. For human missions to the Moon and Mars, an international 20 year program for the first decades of the next millennium is proposed, which requires about $2.5 Billion per year for a manned return to the Moon program and about $2.6 Billion per year for the first 3 manned Mars missions. This is about the annual budget, which is currently spend by the USA only for the operations of its Space Shuttle fleet which generally proofs the affordability of such ambitious programs after the build-up of the International Space Station, when corresponding budget might become again available.     

Past, present, and future: the U.S. EVA program

This paper provides an overview and summary of U.S. extravehicular activity accomplishments of the last 26 years, Space Shuttle missions having scheduled extravehicular activities to be performed over the next several years, extravehicular activities expected to be necessary to support Space Station Freedom assembly tasks and operations, and potential extravehicular activity roles of the NASA Space Exploration Initiative Program.     

Relative efficacy of the proposed Space Shuttle antimotion sickness medications

Space motion sickness has been estimated as affecting between 1/3 and 1/2 of all space flight participants. NASA has at the moment proposed a combination of promethazine and ephedrine (P/E) and one of scopolamine and dextroamphetamine (S/D), both given orally, as well as a transdermally applied scopolamine (TAS), as preventive and ameliorative measures. The reported double-blind study, tests the early phase actions and efficacy of the transdermal scopolamine (Transderm (TM)-V of ALZA Corporation) and compares these in detail to the oral medications. Motion sickness resistance was tested by standardized head movements while accelerating at 0.2 degree/sec2 to a maximum rotation of 240 degrees/sec, with an intermediate plateau of 10 min at 180 degrees/sec. To permit weighting motion sickness protection against other system influences, cardiovascular, psychological (subjective and objective), and visual parameter changes were documented for the three therapeutic modes. The relative impact of the various modalities on operational and experimental components of space missions is discussed. A comparison to intramuscularly administered promethazine (a backup therapeutic mode suggested for Space Shuttle use) is also included.     

Assessing the legacy of the Space Shuttle

This article reviews the core legacies of the Space Shuttle program after 25 years and suggests that, while it was not an unadulterated success, on balance the Shuttle served a valuable role in the development of spaceflight and deserves an overall positive assessment in history. There are five core legacies that deserve discussion. First, the Space Shuttle has a reputation as a mistake resulting from a policy failure that should never have been pursued. Second, it has been criticized as a program that prohibited other paths for the US space program. Third, and more positively, the Space Shuttle provided more than two decades of significant human spaceflight capability and stretched the nature of what could be accomplished in Earth orbit much beyond where it had previously been. Fourth, it served as a relatively flexible platform for scientific activities. Finally, and perhaps most significantly since the US human spaceflight program has always been focused on national prestige, the Space Shuttle served well as a symbol of American technological verisimilitude.     

The cost benefits of the Spacelab system to scientific investigations and space applications

In the past, one of the major problems in performing scientific investigations in space has been the high cost of developing, integrating, and transporting scientific experiments into space. The limited resources of unmanned spacecraft, coupled with the requirements for completely automated operations, was another factor contributing to the high costs of scientific research in space. In previous space missions after developing, integrating and transporting costly experiments into space and obtaining successful data, the experiment facility and spacecraft have been lost forever, because they could not be returned to earth. The objective of this paper is to present how the utilization of the Spacelab System will result in cost benefits to the scientific community, and significantly reduce the cost of space operations from previous space programs.The following approach was used to quantify the cost benefits of using the Spacelab System to greatly reduce the operational costs of scientific research in space. An analysis was made of the series of activities required to combine individual scientific experiments into an integrated payload that is compatible with the Space Transportation System (STS). These activities, including Shuttle and Spacelab integration, communications and data processing, launch support requirements, and flight operations were analyzed to indicate how this new space system, when compared with previous space systems, will reduce the cost of space research. It will be shown that utilization of the Spacelab modular design, standard payload interfaces, optional Mission Dependent Equipment (MDE), and standard services, such as the Experiment Computer Operating System (ECOS), allow the user many more services than previous programs, at significantly lower costs. In addition, the missions will also be analyzed to relate their cost benefit contributions to space scientific research.The analytical tools that are being developed at MSFC in the form of computer programs that can rapidly analyze experiment to Spacelab interfaces will be discussed to show how these tools allow the Spacelab integrator to economically establish the payload compatibility of a Spacelab mission.The information used in this paper has been assimilated from the actual experience gained in integrating over 50 highly complex, scientific experiments that will fly on the Spacelab first and second missions. In addition, this paper described the work being done at the Marshall Space Flight Center (MSFC) to define the analytical integration tools and techniques required to economically and efficiently integrate a wide variety of Spacelab payloads and missions. The conclusions reached in this study are based on the actual experience gained at MSFC in its roles of Spacelab integration and mission managers for the first three Spacelab missions. The results of this paper will clearly show that the cost benefits of the Spacelab system will greatly reduce the costs and increase the opportunities for scientific investigation from space.     

NASA's in-space technology experiments program: Status and plans

Experience with the Shuttle and free-flying satellites as technology test beds has shown the feasibility and desirability of using space assets as facilities for technology development. Thus, by the time the space station era arrives, technologists will be ready for an accessible engineering facility in space. Along with the scientific and commercial space development communities, the technology development community has been participating in defining requirements for this in-space facility. As the 21st century is approached, it is expected that many flights to the Space Station Freedom will carry one or more RT&E experiments. The experiments are likely to utilize both the pressurized volume, and the external payload attachment facilities. Based on the success of instrumenting the Shuttle itself to obtain ascent and descent aerothermodynamic data a unique, but extremely important, class of experiments will use the space station itself as an experimental vehicle.