Optimizing a constellation of space, air, and ground assets is typically a man-in-the-loop intensive and iterative process. Designers must originate a few baseline concepts and then intuitively explore design variations within a large multi-dimensional trade space. To keep the search manageable, options and variations are often severely limited. There is a clear advantage to automate, in an intelligent and efficient manner, this search for optimal design solutions. Such automation would greatly open the analyzable options, increasing insight, improving solutions, and saving money. For this reason, Boeing has initiated a software application that automates STK® scenarios and intelligently searches for optimal solutions. Now in the post-prototype stages of development, “AVA” has provided extremely valuable solutions and insight into several space-based architectures and their proposed payloads. This paper will discuss the current state of the AVA tool, methods, applicability, and the potential for future growth.
Aximetric proposes Distributed Command and Control (C2) architecture for autonomous on-orbit assembly in space with our unique vision and sensor driven docking mechanism. Aximetric is currently working on ip based distributed control strategies, docking/mating plate, alignment and latching mechanism, umbilical structure/cord designs, and hardware/software in a closed loop architecture for smart autonomous demonstration utilizing proven developments in sensor and docking technology. These technologies can be effectively applied to many transferring/conveying and on-orbit servicing applications to include the capturing and coupling of space bound vehicles and components.
The autonomous system will be a “smart” system that will incorporate a vision system used for identifying, tracking, locating and mating the transferring device to the receiving device. A robustly designed coupler for the transfer of the fuel will be integrated. Advanced sealing technology will be utilized for isolation and purging of resulting cavities from the mating process and/or from the incorporation of other electrical and data acquisition devices used as part of the overall smart system.
The future of business intelligence in space exploration will focus on the intelligent system-of-systems real-time enterprise. In present business intelligence, a number of technologies that are most relevant to space exploration are experiencing the greatest change. Emerging patterns of set of processes rather than organizational units leading to end-to-end automation is becoming a major objective of enterprise information technology. The cost element is a leading factor of future exploration systems. This technology project is to advance an integrated Planning and Management Simulation Model for evaluation of risks, costs, and reliability of launch systems from Earth to Orbit for Space Exploration. The approach builds on research done in the NASA ARC/KSC developed Virtual Test Bed (VTB) to integrate architectural, operations process, and mission simulations for the purpose of evaluating enterprise level strategies to reduce cost, improve systems operability, and reduce mission risks. The objectives are to understand the interdependency of architecture and process on recurring launch cost of operations, provide management a tool for assessing systems safety and dependability versus cost, and leverage lessons learned and empirical models from Shuttle and International Space Station to validate models applied to Exploration. The systems-of-systems concept is built to balance the conflicting objectives of safety, reliability, and process strategy in order to achieve long term sustainability. A planning and analysis test bed is needed for evaluation of enterprise level options and strategies for transit and launch systems as well as surface and orbital systems. This environment can also support agency simulation based acquisition process objectives. The technology development approach is based on the collaborative effort set forth in the VTB's integrating operations, process models, systems and environment models, and cost models as a comprehensive disciplined enterprise analysis environment. Significant emphasis is being placed on adapting root cause from existing Shuttle operations to exploration. Technical challenges include cost model validation, integration of parametric models with discrete event process and systems simulations, and large-scale simulation integration. The enterprise architecture is required for coherent integration of systems models. It will also require a plan for evolution over the life of the program. The proposed technology will produce long-term benefits in support of the NASA objectives for simulation based acquisition, will improve the ability to assess architectural options verses safety/risk for future exploration systems, and will facilitate incorporation of operability as a systems design consideration, reducing overall life cycle cost for future systems.
A dynamic simulation & validation capability has been developed for mechanical systems design and analysis at Boeing Huntington Beach in the past decade. The technology has been applied to several high-profile space programs, such as Mission to Mir, and International Space Station (ISS) with great success, and plays an important role in the development of Orbital Express and Delta IV programs. NASA has embraced the approach, and has strongly promoted its application on the ISS and other programs. In this paper, the capability is applied for anomaly simulation and resolution of ISS solar array deployment and both simulation and test results are reported.
BSS developed a new generation high power (~20kW) solar array to meet the customer demands. The high power solar array had the north and south solar wings of which designs were identical. Each side of the solar wing consists of three main conventional solar panels and the four-side panel swing-out new design. The fully deployed solar array surface area is 966 ft2. It was a quite challenging task to define the solar array's optimum design parameters and deployment scheme for such a huge solar array's successful deployment and on-orbit maneuvering. Hence, a deployable seven-flex-panel solar wing nonlinear math model and a fully deployed solar array/bus-payload math model were developed with the Dynamic Analysis and Design System (DADS) program codes utilizing the inherited and empirical data. Performing extensive parametric analyses with the math model, the optimum design parameters and the orbit maneuvering /deployment schemes were determined to meet all the design requirements, and for the successful solar wing deployment on-orbit.
The Advanced Video Guidance Sensor (AVGS), an active sensor system that provides near-range 6-degree-of-freedom sensor data, has been developed as part of an automatic rendezvous and docking system for the Demonstration of Autonomous Rendezvous Technology (DART). The sensor determines the relative positions and attitudes between the active sensor and the passive target at ranges up to 300 meters. The AVGS uses laser diodes to illuminate retro-reflectors in the target, a solid-state imager to detect the light returned from the target, and image capture electronics and a digital signal processor to convert the video information into the relative positions and attitudes. The development of the sensor, through initial prototypes, final prototypes, and three flight units, has required a great deal of testing at every phase, and the different types of testing, their effectiveness, and their results, are presented in this paper, focusing on the testing of the flight units. Testing has improved the sensor’s performance.
One of the important components of the Virtual System Integration (VSI) process is subsystem testing. The Orbital Express Capture System (OECS), an important subsystem of the DARPA/Boeing Orbital Express Program Demonstration System, was put through 6 DOF testing at the Marshall Space Flight Center Contact Dynamics Simulation Laboratory. Aims of the testing were two-fold: verify proper functionality of the system in a flight-like test to give early indication of any design issues, and provide appropriate test data for correlation and validation of the capture system dynamics analysis model to support OECS verification.
This paper will briefly review the VSI process, the Orbital Express program, the Orbital Express Capture System and describe recent 6 DOF testing of the Orbital Express 6 DOF Capture System.
The scope of the analysis was to determine the capability of the Michigan Aerospace Corporation (MAC) Autonomous
Docking Satellite System II (referred to as 'ASDS' for the remainder of this paper), and to develop and mature the concept.
The integrated system model included detailed subsystem models. A cable model was developed from the test data that resulted in good correlation. A high fidelity subsystem model of the cam resistance force was modeled. The integrated system model also includes contact definitions, final latching/locking definition, and various sensors.
Over 3,000 cases were analyzed to identify areas where the MAC docking concept can be improved. Sensitivity and Monte Carlo studies were completed to understand the mechanism’s capture capability, determine subsystem requirements, and evolve the design for improved performance.
As missions expand to a sustainable presence in the Moon, and extend
for durations longer than one year in lunar outpost, the
effectiveness of the instrumentation and hardware has to be
revolutionized if NASA is to meet high levels of mission safety,
reliability, and overall success. This paper addresses a method of
non-intrusive local inspection of surface and sub-surface
conditions, interfaces, laminations and seals in both space vehicle
and ground operations with an integrated suite of imaging sensors
during pre-launch operations. It employs an advanced Raman
spectrometer with additional spectrometers and lidar mounted on a
flying robot to constantly monitor the space hardware as well as
inner surface of the vehicle and ground operations hardware. A team
of micro flying robots with necessary sensors and photometers is
required to internally and externally monitor the entire space
vehicle. The micro flying robots should reach an altitude with least
amount of energy, where astronauts have difficulty in reaching and
monitoring the materials and subsurface faults. The micro flying
robots have an embedded fault detection system which acts as an
advisory system and in many cases micro flying robots act as a
`Supervisor' to fix the problems. The micro flying robot uses
contra-rotating propellers powered by an ultra-thin, ultrasonic
motor with currently the world's highest power weight ratio, and is
balanced in mid-air by means of the world's first stabilizing
mechanism using a linear actuator. The essence of micromechatronics
has been brought together in high-density mounting technology to
minimize the size and weight. Each robot can take suitable payloads
of photometers, embedded chips for image analysis and micro pumps
for sealing cracks or fixing other material problems. This paper
also highlights advantages that this type of non-intrusive
techniques offer over costly and monolithic traditional techniques.
Is the SSPK (Single Shot Probability of Kill) sufficient to represent a kill vehicle performance? This question is often asked because the SSPK computation ignores the details of the miss distance performance and considers only the threshold limit of the miss distance. One may intuitively think that a KV (kill vehicle) with a smaller average miss distance should perform better than the one with a larger distance. In this case the SSPK alone may not be sufficient to represent a KV performance. This paper, however, will show that the SSPK and the miss distance performance are related (i.e., a higher SSPK means a smaller average miss distance, and vice versa) and therefore the SSPK is a sufficient KV performance measure. The relationship is derived based on the observation that KV miss distance obeys Rayleigh statistics.
Subsurface damage control and measurement is critical on a wide range of optical elements. The amount of subsurface damage present in an optic determines its yield strength, the amount of laser power that the optic can handle, and the flatness that can be maintained during the coating process. In these days of reduced tolerance for mission failure, it is critical to have accurate knowledge of the condition of an optic before sending it into space. Destructive tests provide very accurate measurements of subsurface damage, but such testing can be time consuming and an uncertainty always remains: Does the finished part have the same subsurface properties as the measured sample? Various laser scattering techniques currently provide non-destructive measurement of subsurface measurement, but these measurements are all indirect. The laser scattering techniques directly measure the amount of laser light scattered from a surface and below, which is then correlated to an approximate depth of subsurface damage that might produce the measured amount of scattering. In contrast, the technique presented here is both a non-destructive and direct measurement of the depth and extent of subsurface damage. Because it is a direct measurement, subsurface damage depth can be reported in real time, allowing for in-process corrections and optimizations. This paper presents the measurement setup and offers an example of the experimental output provided by this new method.
The problem of Attitude Recovery of rigid and flexible spacecraft/satellite is investigated using the feedback linearization control approach. The attitude and flexible dynamics equations for a class of spacecraft/satellite are presented. Since the flexible spacecraft is under-actuated, the input-output linearization technique was specifically used to break up the system into two distinct parts, namely (1) an external linearizable system for which a linear controller can be easily implemented and (2) an internal nonlinear unobservable system for which the associated zero dynamics is shown to be asymptotically stable for a representative case. The overall closed-loop stability of the flexible satellite is analyzed rigorously and shown to be asymptotically stable using Lyapunov's method. In order to design and analyze attitude control system for satellites, it is important to be able to simulate the dynamics of the spacecraft. Hardware-in-the-loop simulations of a spacecraft, such as air-bearing spacecraft simulators, are not only expensive to build, but they cannot provide the full experience of micro-gravity. An alternative is to have a high fidelity software simulator. Consequently, the resulting nonlinear and coupled equations of the satellite are implemented into a high-fidelity, user-friendly simulation environment, named the Flexible Spacecraft Simulator (FS2). The development and utilization of the FS2 for our research will also be presented.
For complex unmanned docking missions, limited communication bandwidth and delays do not allow ground operators to have immediate access to all real-time state information and hence prevent them from playing an active role in the control loop. Advanced control algorithms are needed to make mission critical decisions to ensure safety of both spacecraft during close proximity maneuvers. This is especially true when unexpected contingencies occur. These algorithms will enable multiple space missions, including servicing of damaged spacecraft and missions to Mars. A key characteristic of spacecraft servicing missions is that the target spacecraft is likely to be freely tumbling due to various mechanical failures or fuel depletion. Very few technical references in the literature can be found on autonomous docking with a freely tumbling target and very few such maneuvers have been attempted. The MIT Space Systems Laboratory (SSL) is currently performing research on the subject. The objective of this research is to develop a control architecture that will enable safe and fuel-efficient docking of a thruster based spacecraft with a freely tumbling target in presence of obstacles and contingencies. The approach is to identify, select and implement state estimation, fault detection, isolation and recovery, optimal path planning and thruster management algorithms that, once properly integrated, can accomplish such a maneuver autonomously. Simulations and demonstrations on the SPHERES testbed developed by the MIT SSL will be executed to assess the performance of different combinations of algorithms. To date, experiments have been carried out at the MIT SSL 2-D Laboratory and at the NASA Marshall Space Flight Center (MSFC) flat floor.
A space tug vehicle is designed to rendezvous and dock with a space object; make an assessment of its current position, orientation, and operational status; and then either stabilize the object in its current orbit or move the object to a new location with subsequent release. A subset of on-orbit servicing, space tug missions in the geosynchronous belt include stationkeeping of satellites which have lost attitude control and repositioning of satellites. Repositioning of spacecraft may be desirable as a means to rescue satellites launched into incorrect orbits, for the retirement of satellites into “graveyard” orbits, and for on-demand maneuvers that support flexible mission requirements. This paper aims to unify the political, legal, operational, and financial aspects of the space tug concept and highlight the challenges that stand in the way of an operational space tug vehicle. U.S. Space Transportation Policy is reviewed, and a space tug operation is recognized as an enabler of emerging national space transportation requirements. Customary international and United States laws are explored as potential constraining forces on future tug missions. A concept of operations in geosynchronous orbit, including parking orbit selection and approach strategies, is analyzed with emphasis placed on safety and reliability. Potential financing models and the issue of insurance for space tugs are discussed and identified as the principal challenges facing implementation of a space tug system. This paper offers a positive forecast for the future of on-orbit servicing and endorses continued government support for proof-of-concept missions.
Russia began its own satellites early warning system at the end of the 60’s with the development of US-K satellites (known as OKO) to make up for lost time vis-a-vis the USA (MIDAS, VELA, DSP). More than 90 satellites were launched between 1972 and 2003 to build up the satellite constellation of the early warning system. This paper first describes the historic background of development and set-up of the Russia's satellite constellation. The current state of Russia's satellite early warning system is then presented, i.e. the number of satellites supposed to be operational, selected orbits. Operational capabilities are assessed in terms of geometrical visibility, coverage or availability. The last part of this paper gives a quick overview of other early warning systems (in operation or underway) in others countries.
The widespread use of laser line scanners (LLS) aboard autonomous underwater vehicles (AUV) and remotely operated vehicles (ROV) in the last decade has opened a unique window to a series of homeland security applications. Numerical experiments were performed to calculate the target signal and the effect of background medium (bottom, water) signals on target identification of fan-type LLS (Real-time Ocean Bottom Optical Topographer, ROBOT). Several 2-D Monte Carlo simulations were run with various bottom albedos, optical properties of the water, laser wavelengths, target distances, and source-detector angles. A forward 1-D Monte Carlo model was validated using Hydrolight based on upwelling and downwelling irradiance values computed at different depths. Signal/noise values (S/N) at the ROBOT detector were obtained by dividing the target peak by the path-radiance peak for each line-spread function. Since bottom-target reflectance was assumed Lambertian, target contribution was symmetrical with respect to the center of the target. Conversely, background contributions evidenced a bulge on the path radiance side of the target center, which was more apparent at higher turbidities. As expected, S/N values were higher when ROBOT was closer to the target. For daylight simulations, system noise includes both LLS path radiance and environmental path and target radiances because they reduce the laser-line contrast. The Hybrid marine optical model (HyMOM) provided the environmental radiance field. Optimum target detection based on laser wavelength and source-detector angle will depend on chosen ambient light conditions and AUV-ROVs altitude settings.