3.2 Space Vehicles

3.2.1 Warfighter Needs

Space vehicle technology goals translate into payoffs to the warfighter in terms of increased warfighter capabilities. Payoffs to satellite systems include lower cost, longer life, and increased reliability for existing and new satellite families. This technology area also provides solutions to numerous AFSPC deficiencies, such as inadequate near-Earth coverage, high O&M costs, inadequate satellite element set accuracy, inadequate terminal mobility, insufficient communications capacity, inaccuracy of data, vulnerability of ground facilities, and slow deployment of space assets. Advanced space sensor, precision orbital structure, and cryogenic technologies will help provide all-weather, day/night operation and detection of airborne targets down to cruise missile size. GPS technology advances allow for improved targeting of Earth-based objects and precision strikes. Sensor, precision orbital structure, and cryogenic technologies are applicable to SBIRS, SMTS, NPOESS, space-based JSTARS, AWACS alternatives, and NASA EOS. Space power transition targets include NPOESS, GPS IIF, SBIRS, MILSTAR, space-based JSTARS, AWACS alternatives, FLEETSATCOM, and SMTS. Communications transition targets are MILSATCOM (e.g., FLEETSATCOM and MILSTAR) as well as any mission requiring high-data-rate transmission.

The USAF has taken steps to transition to a common core telemetry, tracking, and control (TT&C) in the next few years that will support multiple satellite families. Satellite control technology is directed at evolving the core to support existing and future warfighter needs and migrating autonomy for satellite control from the ground segment to the space segment. GN&C technology also supports satellite autonomy, relieving large O&M costs and performing the guidance portion for global delivery of precision conventional warheads. Survivability technology advances include advanced hardening techniques, development of radiation and other environmental effects models, a satisfactory method to allow COTS devices to operate properly in space, and miniaturization of a threat warning and attack reporting package. These will permit any space system to be produced at lower costs and to function longer and more reliably. In addition to the listed systems, advanced electronics technologies enable future space systems that are envisioned to support the warfighter into the 21st century.

3.2.2 Overview

The set of DoD S&T technology efforts included in the space vehicles subarea encompasses thermal management, structures, survivability, GN&C, power, and satellite control.

3.2.2.1 Goals and Timeframes. The subarea goals, system payoffs, and timeframes for the space vehicles technologies are listed in Table VIII-4. The goals and payoffs are shown for both the LEO Surveillance and GEO High-Power Communications applications. The technologies and associated objectives required to achieve the space vehicles goals and payoffs are detailed in Table VIII-5.

3.2.2.2 Major Technical Challenges. The technical challenges in developing advanced technologies and subsystems for space vehicles focus on reducing weight, size, and cost; isolating vibration; and increasing power efficiency, reliability, and overall spacecraft lifetime.

Thermal Management. The technical challenges in this area include mitigation of material stresses, parasitic losses, and contamination sources at low temperatures; improvement in motor and cold interface heat transfer efficiencies; lack of materials with adequate heat capacities at cryogenic temperatures; development of improved adaptive and passive vibrational control; lack of understanding of thermodynamic and fluid flow processes in cryocooler components; difficulty in combining thermal engineering and electronics engineering to introduce high-thermal conductance material into electronics components; development of rapid and reliable startup and long-term operation capability of two-phase capillary devices in zero-g and adverse-g environments; developing advanced materials to dissipate heat fluxes from microelectronics devices and capillary wicks with less than 1 micron pore size; and flexible or rotatable joints for deployable radiators.

Structures. Structures challenges include structural isolation without constraints on rattle space (clearance); understanding dynamics arising from interactions with the space environment, structural materials, individual components, control systems, the launch vehicle, and the spacecraft; cost-effective manufacturing techniques; development of rapid, nonpyrotechnic release mechanisms and high-fidelity, ground-based experimental simulations; increased reliability/ durability of multifunctional structure connections; and deployable, large lightweight structures.

Survivability. The challenges are to develop radiation-tolerant space devices and systems, develop techniques to allow space applications of COTS devices, improve reliable high-precision survivability simulations, develop miniaturized laser and radar threat detectors and optical systems jamming protection, and characterize space debris hazards.

GN&C. The challenges are to mitigate or reduce radiation exposure and plasma effects; eliminate ring laser gyroscope (RLG) mechanical dithering; improve RLG mirror durability; improve light sources, coil selection, and windings for interferometric fiber optic gyroscopes (IFOGs); improve micromachining processes; provide on-board precise time and reliable frequency signals and laser tracking; obtain accurate ephemeris data; and develop hardware/ software interface for autonomous navigation.

Power. The challenges include increased compatibility and applicability of advanced materials in the space environment; more efficient photovoltaics; viability of manufacturing; feasibility of solar concentrators; feasibility of solar thermal conversion; highly reactive chemicals; runaway electrochemical reactions; life limiters in energy storage (e.g., electrode wear); lack of high-voltage, high-power, and high-efficiency space-qualified components fabricated from advanced semiconductors; and lack of space-qualified and optimized circuit design for off-the-shelf components.

Space Electronics and Communications. Technical efforts that are enabling technologies and critical to the success of the space platforms technology area include increasing space radiation hardness of recently available small feature size, high-performance electronics technologies, knowledge of space radiation attenuation properties of advanced structural and packaging materials, advanced packaging to dissipate heat in a vacuum without out-gassing, advanced insulated device technologies, and integrated microelectromechanical systems (MEMS). Communications challenges are development of high-capacity optical communications system area networks; development of an efficient modem; and improvement of the ability to manufacture ultra lightweight, higher frequency antennas, GaAs PHEMT MMIC (gallium arsenide pseudomorphic high-electron mobility transistor monolithic microwave integrated circuits), low-power high-speed custom integrated circuits, silicon carbide devices, and MMICs for high-power radiation research.

Satellite Control. The challenges are to overcome vendor-specific dependencies in COTS software; exploit distributed artificial intelligence capabilities; develop integration of an intelligent trainer with a multisatellite ground system; use model-based reasoning and machine learning for anomaly resolution; reduce development and sustainment costs when DoD does not drive the market; and develop reliable, verifiable artificial intelligence-based systems for payloads that are autonomously self-controlled and self-navigating, and provide information on demand to the warfighter.

3.2.2.3 Related Federal and Private Sector Efforts. Outside DoD, the primary government organizations funding space vehicles technology development are NASA, National Systems, and DOE. Historically, the NASA investment matches that of DoD in many of the technologies, while the DOE investment is considerably smaller. National Systems makes a significant investment in space vehicles technology. Formal coordination with NASA is under the DoD/NASA Aeronautics and Astronautics Coordinating Board. Joint program planning and management of technology development (e.g., NASA/DoD IPT) is coordinated among these organizations and the user community to ensure maximum return on government investment of R&D funding. The related NASA programs of greatest relevance are the New Millennium Program and the Small Satellite Technology Initiative. Various pervasive technologies, such as space power, thermal management, and structures, are closely coordinated with the responsible NASA technology centers. Industry is estimated to be investing $220 million of their IR&D funds in related space technology. This work is typically focused on developing a competitive capability for near- and far-term corporate goals. Additionally, there are focused commercial ventures for space-based systems, such as communication and surveillance systems, that complement these efforts. The recent appearance of a strong, well-capitalized commercial presence in space allows DoD to leverage advances in these systems. Commercial space manufacturers' private capital, short development cycle, and frequent new starts permit a new arena for rapid maturation of space platform technology. DoD has formed a cooperative research and development agreement (CRDA) with the commercial sector to provide opportunities for space demonstration of the technology and to share in the cost of development in some areas, such as energy storage. Industry has plans for both highly autonomous spacecraft and architectures for large, distributed networks of satellites. Similar advances are occurring in the international arena as well.

3.2.3 S&T Investment Strategy

3.2.3.1 Technology Demonstrations. The space vehicles technology demonstration program provides an architecture to assist technologies in the validation and assessment of their performance. The technology demonstration architecture spans from small, component-level assessments to integrated demonstrations that address the use of technology in solving warfighter deficiencies. The overall architecture allows for the validation and assessment of technologies in a simulated ground environment or space environment depending on the needs of the experimenter(s) and the environment required to provide a true assessment and validation of the technologies capabilities in meeting its performance criteria.

USAF Integrated Space Technology Demonstration Program. The USAF ISTD program will demonstrate medium-risk, high-payoff system concepts and payload(s) through the design, integration, and validation of emerging technologies in real-world environments. The objectives of the ISTD program are to show how emerging technologies can be used to resolve high-priority mission deficiencies, validate technology for use in operational systems, examine new methods to demonstrate technologies, and acquire military capability by leveraging commercial space systems.

As the first ISTD mission, Warfighter-1 (WF-1) objectives are to evaluate/validate hyperspectral technologies in the orbital environment, demonstrate utility of hyperspectral imagery to the government user community, demonstrate leveraging of commercial space systems to meet DoD needs, and launch nominally within 36 months of contract award.

The scope of the WF-1 includes design, fabrication, integration, test, launch, spacecraft operations, and algorithm development as well as supporting/performing on-orbit payload operations, mission planning, anomaly resolution, and data reduction and processing. WF-1 will demonstrate emerging sensor technologies and the ability to perform target detection and terrain classification using these technologies. A large portion of the data collected will focus on target and background signatures to serve as a scientific database for algorithm development and exploitation studies within the WF-1 and other programs.

The system requirements for the WF-1 sensor have a minimum of 60 spectral bands in the spectral region between 0.4-2.5 µm. The exact placement and width of the bands is to be determined by system trade studies. The sensor will have a 5-km minimum swath width and a single hypercube image at least 100 km². The sensor will provide hyperspectral data necessary to detect targets (listed in Table VIII-6) against various backgrounds. The WF-1 system will be used to develop a database of terrain classification data for the terrain elements including variations due to seasonal changes, sun/look angles, and atmospheric conditions. Space flight is a cost-effective way to acquire the background data over the wide range of conditions and locations.

The first ISTD flight will demonstrate targeted FY00 DTO goals for Cryogenic Technologies (SP.01.06.F), Space Structures and Control (SP.03.06.NF), High-Density Radiation-Resistant Microelectronics (SE.37.01.FH), Integrated Sensor/Data Fusion Demonstration (D.02), and Digital Warfighting Communications (IS.23.01.AFN). These programs directly support the AFSPC, including the Space Warfare Center, and military users of tactical space imagery.

USAF MightySat. The USAF MightySat program is a quick turnaround series of small, satellite-based experiments that test a limited set of high-payoff emerging and exploratory technologies. These elements can be either in situ experimental bus components (batteries, solar cells, etc.) or standalone experiments (imagers, sensors, etc.). The MightySat platform functions as an experimental test bed exploring such objectives as demonstrating concept feasibility, developing a critical knowledge base to exploit new capabilities, identifying system risks under space environmental conditions, and providing flight heritage for critical components scheduled for deployment on future DoD space systems. Table VIII-7 details the key technology demonstrations within the MightySat program.

Navy Earth-Map Observer Program. The NEMO program is to demonstrate the utility of hyperspectral imagery collection and exploitation in support of naval missions. NEMO will utilize innovative hyperspectral imaging, on-board parallel processing, and advanced algorithms for spectral and spatial feature identification. The program will develop an inexpensive, long-term, Earth-imaging spacecraft to characterize the optical environment in the littoral zone as it affects the performance of Navy optical systems for bathymetry; the evaluation of sea-bottom types; and the detection of mines, submarines, and submerged hazards. NEMO will also demonstrate the intelligence gathering and preparation of battlespace capabilities of hyperspectral sensing for supporting the warfighter. The innovative algorithm to be used on this system is the Optical Real-Time Adaptive Spectral Identification System (ORASIS), which was developed by the Navy. The ORASIS algorithm allows, for the first time, real-time processing of imaging spectrometer data on a spacecraft. The NEMO satellite will be developed in cooperation with industry. Once the prototype has been developed and proven, the technology will be transitioned to industry.

USAF Integrated Ground Demonstration Program. This program is intended to demonstrate high-risk/high-payoff system- and payload-level concepts via the ground integration of emerging technologies. This is accomplished by characterizing technology interfaces and interactions in a simulated environment. This technology integration capability provides the ability for evaluating advanced payload, system, and mission concepts while the hardware and software is still recoverable for future development as well as allowing for the simulation of hardware or software still in the concept phase to be placed in an integrated systems environment. Ground demonstrations, while an important part of the integrated demonstrations effort, are currently not funded.

STP Small Experiments and Demonstrations. The DoD Space Test Program (STP), managed by the Space and Missile Test and Evaluation Directorate, supports technology developers in the Army, Navy, Air Force, BMDO, and DOE by providing these experimenters with the spacecraft bus, integration of the experiment payloads, launch services, and 1 year's on-orbit operations. STP funding is used to support experiments that do not have the funding to provide their own means of access to space. In addition, program management directive (PMD) guidance for STP calls for one small launch vehicle flight (Pegasus-class with satellite of less than 1,000 pounds) every 2 years and one medium launch vehicle flight (Delta-class with satellite of 6,000 to 10,000 pounds) every 4 years. Experiments are selected through the Space Experiments Review Board (SERB) which meets annually to consolidate and prioritize space experiments proposed from all of the services and agencies; experiments are ranked primarily by military relevance.

Although STP-sponsored experiments do not individually have significant funding or visibility, collectively they are the backbone of space vehicle science and technology program. An example of these small experiments is the Navy's Microelectronics and Photonics Test Bed (MPTB). The objectives of the MPTB project are (1) select (by SPOs) devices and subsystems for test, (2) perform ground-based radiation tests, (3) predict space results, (4) construct MPTB space hardware, (5) launch in FY 97, (6) analyze space data, and (7) develop new radiation effects models. The MPTB experiment will space qualify devices and subsystems and demonstrate that COTS devices can operate in selected orbits. Another program, the Missile Technology Demonstration Flight, will demonstrate range safety and instrumentation to augment the use of range radar for safety and range metrics. Other examples that are currently manifested (and the flights they are on) are Electromagnetic Propagation Experiment (STEP 4); Compact Environment Anomaly Sensor (TSX-5); Beryllium-7-Induced Radiation Experiment (Cosmos); and Polar Orbiting Geomagnetic Survey II (DMSP S-15).

3.2.3.2 Technology Development. The space vehicles subarea consists of six technology efforts. Technology advances in all of these efforts are required to achieve the overall goals of this subarea.

Thermal Management. The thermal management effort encompasses the development of cryogenic and conventional spacecraft bus thermal management technologies required for temperatures ranging from 10 to 900 K. Technology development includes replacement of large, heavy, short-lived cryogenic reservoirs with small, lightweight, highly efficient, and long-lived mechanical cryocoolers. Innovative components and system configurations are developed, characterized, and tested for reliability and endurance. These include advanced thermal integration components, very high heat flux heart transfer devices, capillary wicking devices, ambient temperature thermal energy storage, passive and active thermal control devices for cooling of advanced microelectronics devices, and deployable radiators and coatings.

Structures. The structures effort is being conducted to discover new ways of making lightweight, low-cost, and precise structures for space and launch vehicles and to develop new methods to prevent vibration and structural dynamics from degrading the performance of future DoD systems. Other efforts address technology for space vehicles and include concepts for lighter weight, lower cost, higher performance solar array, radiator, antenna, and electronic enclosure structures; multifunctional structures; and smart mechanisms for solar arrays and other deployable structures. Work on inflatable structures for antennas or optics is included in this technology effort. Work on nozzles and thrusters for spacecraft is included in the space propulsion subarea (Section 3.3).

Survivability. The survivability effort includes advanced hardening techniques, models of device response to space radiation, and methods to allow COTS devices to operate properly in the lower dose space radiation orbits.

GN&C. The GN&C effort encompasses autonomous navigation with GPS receiver technology, star trackers, and navigation instruments. A primary objective is to increase navigation and attitude determination accuracy while reducing instrumentation size, power, and mass and increasing operational reliability. Increased accuracy and reliability objectives for GPS technology are space-qualified atomic clock, increased precision, stability, reproducibility with size, power, and mass reduction.

Space Power. The space power effort covers the development of all required components for satellite power subsystems including power generation, energy storage, and power management and distribution. Technology development includes generating nonphotovoltaic energy, investigating alternate photovoltaic material and cell designs, and increasing the solar concentration ratio of arrays. For energy storage, programs include demonstrating life, performance, and safety of NaS cells while working to develop advanced lithium-based batteries. Investigations into flywheels and other nonelectrochemical storage devices have also been started. High-voltage solid-state relays, hybrid control patches, and integrated power chips are key power management technology approaches for the next 5 years.

Satellite Control. Satellite control technology development will investigate user-friendly graphical data viewing, stored data for the life of the satellite, and extensive online data analysis tools; automate data in pass plan manuals, capture expert knowledge in computer-based knowledge bases, and utilize model-based reasoning and machine learning to resolve anomalies; and support reactive, dynamic training integrated into the actual operational system with no human trainer in the loop. Trade studies will be performed to determine which functions have higher payoff for automating on-board from an O&M and survivability perspective. Some ongoing work in autonomous orbit control will be flight tested. Other high-payoff areas will be developed further and readied for experimental flight testing.

3.2.3.3 Basic Research. In addition to the following areas, the space vehicles technology subarea relies on the results of basic research from Information Systems Technology, Materials/ Processes, and Sensors, Electronics, and Battlespace Environment.

Thermal Management. Basic research in this technology effort is focused on cryogenic technology. The objectives of the cryogenic regenerator effort are to measure cryocooler regenerator performance under operating conditions and to develop a numerical model for predicting regenerator performance. Numerical models do not currently exist for transient operation. The technology approach is to develop an experiment that incorporates a pulse tube cryocooler. Operating data will be gathered in the 30-100-Hz range. These data will be compared with existing models for both transient and steady-state operation. Finally, an analytic model will be developed and verified for the transient case.

Structures. Two ongoing basic research efforts are of particular interest in this area. One is developing a fundamental understanding of how the different aspects of the space environment (atomic oxygen, UV, vacuum, protons, electrons, and hypervelocity debris) interact to affect space structures and structural materials. The other effort is exploring development of new mathematical control algorithms and approaches to structural control and vibration damping.

GN&C. Ongoing basic research relating to this technology subarea is in high-temperature superconducting materials and atom traps. Low-temperature, low-noise resonating cavities and the means to trap and interrogate atoms' quantum frequencies may lead to new technologies for generating precise navigation signals in space. GPS receiver applications needing accurate time from very low power accurate oscillators will benefit from these basic efforts.