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Research Outside CODER

Achievable debris orbit prediction accuracy using laser ranging data from a single station
Location:
Wuhan University, RMIT University, EOS Space Systems Ltd
Investigator:
Jizhang Sanga, James C. Bennett
Duration:
2013-2014

Earlier studies have shown that an orbit prediction accuracy of 20 arc sec ground station pointing error for 1–2 day predictions was achievable for low Earth orbit (LEO) debris using two passes of debris laser ranging (DLR) data from a single station, separated by about 24 h. The accuracy was determined by comparing the predicted orbits with subsequent tracking data from the same station. This accuracy statement might be over-optimistic for other parts of orbit far away from the station. This paper presents the achievable orbit prediction accuracy using satellite laser ranging (SLR) data of Starlette and Larets under a similar data scenario as that of DLR. The SLR data is corrupted with random errors of 1 m standard deviation so that its accuracy is similar to that of DLR data. The accurate ILRS Consolidated Prediction Format orbits are used as reference to compute the orbit prediction errors. The study demonstrates that accuracy of 20 arc sec for 1–2 day predictions is achievable.


Laser guide star used to correct for atmospheric turbulence
Adaptive optics for space debris tracking
Location:
Australian National University (ANU) and EOS Space Systems
Investigator:
Francis Bennet, Francois Rigaut, Ian Ritchie and Craig Smith
Duration:
2013 - Present
TRL:
7 - System demonstration in an operational environment

There are many objects of less than 1m in size that are difficult to track with radar. To address this problem we currently use lidar, an active optical tracking technique in which we propagate a laser through a ground-based telescope onto the sky. This system is currently limited to tracking items down to approximately 10cm in size in the range 400–1500km, and larger objects at around 2500km. The researchers have developed an adaptive optics system to increase the range of lidar and reduce the minimum target size. For this they use an artificial star, created by illuminating a portion of the atmosphere with a laser, to measure turbulence. At tracking rates of up to 1 degree per second, the artificial beacon must be quite strong, and the information from it processed very quickly to keep up with the rate of change of sky zones needing turbulence correction. This is a major challenge for the project. A deformable mirror corrects this turbulence, enabling us to better focus the laser beam on the target in orbit, increasing the maximum range and decreasing the minimum target size.


An adaptive threshold method for improving astrometry of space debris CCD images
Location:
Purple Mountain Observatory, Chinese Academy of Sciences
Investigator:
Rong-yu Sun, Chang-yin Zhao
Duration:
2013-2014

Optical survey is a main technique for observing space debris, and precisely measuring the positions of space debris is of great importance. Due to several factors, e.g. the angle object normal to the observer, the shape as well as the attitude of the object, the variations of observed characteristics for low earth orbital space debris are distinct. When we look at optical CCD images of observed objects, the size and brightness are varying, hence it’s difficult to decide the threshold during centroid measurement and precise astrometry. Traditionally the threshold is given empirically and constantly in data reduction, and obviously it’s not suitable for data reduction of space debris. Here we offer a solution to provide the threshold. Our method assumes that the PSF (point spread function) is Gaussian and estimates the signal flux by a directly two-dimensional Gaussian fit, then a cubic spline interpolation is performed to divide each initial pixel into several sub-pixels, at last the threshold is determined by the estimation of signal flux and the sub-pixels above threshold are separated to estimate the centroid. A trail observation of the fast spinning satellite Ajisai is made and the CCD frames are obtained to test our algorithm. The calibration precision of various threshold is obtained through the comparison between the observed equatorial position and the reference one, the latter are obtained from the precise ephemeris of the satellite. The results indicate that our method reduces the total errors of measurements, it works effectively in improving the centering precision of space debris images.


Analysis of the optical scattering characteristics of different types of space targets
Location:
Beijing Aerospace Control Center
Investigator:
Yi Han, Huayan Sun, Jianguang Feng, Liang Li
Duration:
2014

This paper mainly focused on the measurement, evaluation and potential identification methods of the unresolved space target's photometric characteristics. The bidirectional reflectance distribution function (BRDF) measurement system was introduced first, and then the measurement error of BRDF and its influence on target's optical cross section (OCS) and magnitude were analyzed. Then, different space targets' OCS and magnitude changing with different factors, such as surface materials and shapes, flying conditions and working states, were analyzed respectively, and some general inclusions of variation laws were deduced. This research can provide references for future studies on space target classification and identification based on the photometric measurement data.


Improving the Precision of Astrometry for Space Debris
Location:
Key Laboratory of Space Object and Debris Observation, Purple Mountain Observatory, Chinese Academy of Sciences
Investigator:
Rongyu Sun, Changyin Zhao, Xiaoxiang Zhang
Duration:
2013-2014

The data reduction method for optical space debris observations has many similarities with the one adopted for surveying near-Earth objects; however, due to several specific issues, the image degradation is particularly critical, which makes it difficult to obtain precise astrometry. An automatic image reconstruction method was developed to improve the astrometry precision for space debris, based on the mathematical morphology operator. Variable structural elements along multiple directions are adopted for image transformation, and then all the resultant images are stacked to obtain a final result. To investigate its efficiency, trial observations are made with Global Positioning System satellites and the astrometry accuracy improvement is obtained by comparison with the reference positions. The results of our experiments indicate that the influence of degradation in astrometric CCD images is reduced, and the position accuracy of both objects and stellar stars is improved distinctly. Our technique will contribute significantly to optical data reduction and high-order precision astrometry for space debris.


Short-arc tracklet association for geostationary objects
Location:
German Space Operations Center, Astronomical Institute, University of Bern
Investigator:
J.A. Siminskia, O. Montenbrucka, H. Fiedlera, T. Schildknechtb
Duration:
2013-2014

Measurement association and initial orbit determination is a fundamental task when building up a database of space objects. This paper proposes an efficient and robust method to determine the orbit using the available information of two tracklets, i.e. their line-of-sights and their derivatives. The approach works with a boundary-value formulation to represent hypothesized orbital states and uses an optimization scheme to find the best fitting orbits. The method is assessed and compared to an initial-value formulation using a measurement set taken by the Zimmerwald Small Aperture Robotic Telescope of the Astronomical Institute at the University of Bern. False associations of closely spaced objects on similar orbits cannot be completely eliminated due to the short duration of the measurement arcs. However, the presented approach uses the available information optimally and the overall association performance and robustness is very promising. The boundary-value optimization takes only around 2% of computational time when compared to optimization approaches using an initial-value formulation. The full potential of the method in terms of run-time is additionally illustrated by comparing it to other published association methods.


Space Debris Measurement Using Joint Mid-Latitude and Equatorial Optical Observations
Location:
Univ. di Roma La Sapienza
Investigator:
Piergentili, F., Ceruti, A., Rizzitelli, F., Cardona, T., Battagliere, M.L., Santoni, F.
Duration:
2014

A system for orbital object monitoring is analyzed, based on a mid-latitude and an equatorial observatory. The enhancements with respect to the use of a single telescope located at mid-latitude, for space debris detection and tracking are highlighted in terms of surveying volume, object identification, and orbital determination accuracy. The need to improve observation capabilities in monitoring and cataloguing such kinds of objects is constantly growing, due to the constant increase of operative satellites and space debris in both geostationary Earth orbit (GEO) and low Earth orbit (LEO) regions. After the considerations on the feasibility of the whole system, an overview of the observatories' design is sketched, on the basis of previous Italian experience in space debris observation, and taking into account constraints imposed by the instrumentation. In particular the main characteristics of components, software for image analysis and observation methodologies are analyzed and a possible configuration is given, based on the ALMASCOPE observatory realized by the Space Robotics Group at the University of Bologna. This observatory was used for the 2010 test campaign carried out from the Broglio Space Center in Kenya.


Tracking the Trajectory of Space Debris in Close Proximity via a Vision-Based Method
Location:
Univ. of Central Florida
Investigator:
N. Li, Y. Xu, G. Basset, N. G. Fitz-Coy
Duration:
2014

The increasingly cluttered environment in space is placing a premium on future spacecraft and satellites that are capable of tracking and estimating the trajectory of unknown space debris autonomously without consistent communication with ground stations. In this paper, a vision-based debris trajectory–tracking method in close proximity is presented using two cameras onboard of two satellites in a formation. To differentiate the target debris from other clutters, a data-association technique is investigated. A two-stage nonlinear robust controller is developed to adjust the attitude of the satellites such that the target debris can be maintained within the field of view of the onboard cameras. Capabilities of the proposed estimation and control methods are validated in the simulations.

 

 


Example Outside Project
Location:
school, department, lab or company as appropriate
Investigator:
Mrs. Donna Investigator
Duration:
This is the period of performance
TRL:
This is the technology readiness level

This is a paragraph describing the research.


Local debris congestion in the geosynchronous environment with population augmentation
Location:
University of Colorado
Investigator:
Paul V. Anderson, Hanspeter Schaub
Duration:
2013

 

Forecasting of localized debris congestion in the geostationary (GEO) regime is performed to investigate how frequently near-miss events occur for each of the longitude slots in the GEO ring. The present-day resident space object (RSO) population at GEO is propagated forward in time to determine current debris congestion conditions, and new probability density functions that describe where GEO satellites are inserted into operational orbits are harnessed to assess longitude-dependent congestion in “business-as-usual” launch traffic, with and without re-orbiting at end-of-life. Congestion forecasting for a 50-year period is presented to illustrate the need for appropriately executed mitigation measures in the GEO ring. Results indicate that localized debris congestion will double within 50 years under current 80% re-orbiting success rates.

 


Local orbital debris flux study in the geostationary ring
Location:
University of Colorado
Investigator:
Paul V. Anderson, Hanspeter Schaub
Duration:
2012-2013

A local orbital debris flux analysis is performed in the geostationary (GEO) ring to investigate how frequently near-miss events occur for each longitude slot in the GEO ring. The current resident space object (RSO) environment at GEO is evaluated, and publicly-available two-line element (TLE) data are utilized in tandem with a geostationary torus configuration to simulate near-miss events incurred by the trackable RSO population at GEO. Methodology for determining near-miss events with this formulation is introduced, and the results of the analysis for a one-year time frame are provided to illustrate the need for active GEO remediation.


On the effects of solar storms to the decaying orbital space debris
Location:
Bandung Institute of Technology
Investigator:
Dhani Herdiwijaya & Abdul Rachman
Duration:
2012

Any man-made object in Earth's orbit that no longer serves a useful purpose is classified as orbital debris. Debris objects come from a variety of sources. The majority is related to satellite fragmentation. Other major sources of debris are propulsion systems, and fragmentation of spent upper stages, payload and mission related debris. Serious concern about orbital debris has been growing. Knowledge of the future debris environment is important to both satellite designers, and mission planners, who need to know what hazards a satellite might encounter during the course of its mission. Therefore, it is important to know how much debris is in orbit, where it is located, and when it will decay. The debris environment is complex and dynamically evolving. Objects of different shape and size behave differently in orbit. The geoeffectiveness space environments include solar flux at 10.7 cm, solar energetic particles flux or speed, solar wind flow pressure, electric field, and geomagnetic indices. We study the decaying orbital debris from Tracking andImpact Prediction (TIP) messages in conjuction with geoeffectiveness space environments through time epoch correlation. We found that the decaying and reentry orbital debris are triggered by space environment enhancement within at least one week before reentry. It is not necessary a transient or high energetic and severe solar storm events are needed in decaying processes. We propose that the gradual enhancement processes of space environment will cause satellite surface charging due to energetic electron and enhancedrag force.


A fast numerical approach for Whipple shield ballistic limit analysis
Location:
Beijing University of Aeronautics and Astronautics
Investigator:
Xiao-tian Zhang, Guang-hui Jia, Hai Huang
Duration:
2013

Whipple shield is widely used on manned spacecraft, numerical simulation is an important way for obtaining the ballistic limit. The large population of particles and the large space span of Whipple shield simulation model restrict the computational efficiency. A fast numerical approach is presented for Whipple shield ballistic limit analysis. First, the critical penetration analysis of the rear walls is converted into specific impulse analysis delivered by the secondary debris cloud, because the maximum of specific impulse is the main determinant of the penetration. The dual plate simulation model is then converted into single plate model and the population of particles is reduced. Second, based on the isotropic expansion theory of secondary debris cloud, the specific impulse analysis is further converted into particle position and velocity analysis when the stable secondary debris formed. The space span of the simulation model is reduced. An example of Whipple shield ballistic limit analysis is provided for the verification of the fast numerical approach, it shows that this approach can significantly increase the computation efficiency with acceptable accuracy.


An approach for constituting double/multi wall BLE by single wall BLE of spacecraft shield
Location:
School of Astronautics, Beihang University
Investigator:
Xiaotian Zhang, Guanghui Jia, Hai Huang
Duration:
2013-2014

Ballistic limit equation (BLE) is an important tool for spacecraft shield design. An approach for constituting dual/multi wall BLE by single wall BLE is proposed. A new single wall BLE is built first based on the current BLE form analysis. A total of 100 experimental test data collected from the literature are introduced for verifications and comparisons. The new single wall BLE has obtained a better correct prediction rate of 83% than other tested BLEs. Secondly, the new Whipple shield (double wall) BLE is constituted of the new single wall BLE. In the low velocity regime the projectile isn't completely fragmented behind the bumper, the Whipple shield BLE is therefore obtained just by the summation of the single wall BLEs of the bumper and the rear wall. While in the hypervelocity regime, the expansion effect of the completely fragmented debris cloud is taken into consideration. The single wall BLE of the rear wall is multiplied by a correction term of the spacing between the two walls before the summation. The shatter regime BLE is obtained by the linear interpolation of the endpoints. A total of 268 experimental test data collected from the literature are introduced for verifications and comparisons. The new Whipple shield BLE has obtained a better correct prediction rate of 72% than other tested BLEs. Finally, the new multi-shock shield BLE is preliminarily constituted of the new single wall BLE and the Whipple shield BLE. The new multi-shock BLE is used to predict 5 experimental test cases and all of which are correct.


Hypervelocity Impact Phenomenon in Bulk Metallic Glasses and Composites
Location:
JPL, CalTech
Investigator:
Lee Hamill, Scott Roberts, Marc Davidson, William L. Johnson, Steven Nutt, Douglas C. Hofmann
Duration:
2013

Collisions with debris are major cause of concern for spacecraft and satellites. Developing new materials that can combat these threats, while still providing low-density and sufficient toughness to survive launch loads, is important for future spacecraft design. In the current work, hypervelocity impacts are used to estimate the ballistic limit for bulk metallic glass and their composites and to investigate spalling behavior. The composites are shown to have excellent combinations of hardness and toughness for use as shields.


New Concepts of Deployable De-Orbit and Re-Entry Systems for CubeSat Miniaturized Satellites
Location:
Department of Industrial Engineering, University of Naples
Investigator:
Valerio Carandente, Raffaele Savino

In the present work new concepts of de-orbit and re-entry modules for standard CubeSats are presented. On the one hand, these modules can be very useful to contrast the growing phenomenon of the Space debris and, on the other hand, to recover Cubesat payload and components after the end of the mission. The concepts are mainly based on deployable, umbrella-like, structures, useful to perform de-orbit and re-entry operations taking advantage from a substantial reduction of the ballistic coefficient. In the de-orbit configuration the deployable structure works only as an aerobrake. In this case the satellite lifetime may be strongly reduced, making it possible to match the CubeSat maximum decay requirement of 25 years, even for altitudes larger than 700 km. In the Earth re-entry configuration the ballistic parameter reduction produces also a sensible decrease of the aerothermal loads on the system, giving the opportunity to recover payload, potential data and satellite components. In this case the umbrella-like structure has both the function to protect the capsule and to control de-orbit and re-entry trajectories, in order to safely reach the desired landing site. The structure can be deployed by means of preloaded springs or other actuators and, once the umbrella is opened, the reference surface can be adjusted to control the trajectory with a kinematic mechanism driven by an electro-mechanical actuator.


Numerical Simulation of Impact Damage Induced by Orbital Debris on Shielded Wall of Composite Overwrapped Pressure Vessel
Location:
Department of Mechanical Engineering, University of Manitoba
Investigator:
Aleksandr Cherniaev, Igor Telichev
Duration:
2014

This paper presents a methodology for numerical simulation of the formation of the front wall damage in composite overwrapped pressure vessels under hypervelocity impact. Both SPH particles and Lagrangian finite elements were employed in combination for numerical simulations. Detailed numerical models implementing two filament winding patterns with different degree of interweaving were developed and used to simulate 2.5 km/s and 5.0 km/s impacts of 5 mm-diameter spherical aluminum-alloy projectile. Obtained results indicate that winding pattern may have a pronounced effect on vessel damage in case of orbital debris impact, influencing propagation of the stress waves in composite material.


Processing optimized for symmetry in the problem of evasive maneuvers
Location:
Departamento de Física, Universidade Estadual de Feira de Santana
Investigator:
Antônio Delson C. de Jesus, Rafael Ribeiro de Sousa
Duration:
2013

The increasing number of space debris in operating regions around the earth constitutes a real threat to space missions. The goal of the research is to establish appropriate scientific-technological conditions to prevent the destruction and/or impracticability of spacecraft in imminent collision in these regions. A definitive solution to this problem has not yet been reached with the degree of precision that the dynamics of spatial objects (vehicle and debris) requires mainly due to the fact that collisions occur in chains and fragmentation of these objects in the space environment. This fact threatens the space missions on time and with no prospects for a solution in the near future. We present an optimization process in finding the initial conditions (CIC) to collisions, considering the symmetry of the distributions of maximum relative positions between spatial objects with respect to the spherical angles. For this, we used the equations of the dynamics on the Clohessy–Witshire, representing a limit of validation that is highly computationally costly. We simulate different maximum relative positions values of the corresponding initial conditions given in terms of spherical angles. Our results showed that there are symmetries that significantly reduce operating costs, such that the search of the CIC is advantageously carried out up to 4 times the initial processing routine. Knowledge of CIC allows the propulsion system operating vehicle implement evasive maneuvers before impending collisions with space debris.


Rendering of the Curimba 12U Cubesat with Solar Panels Deployed
A Cooperative Multi-Satellite Mission for Controlled Active
Location:
Embry Riddle Aeronautical University
Investigator:
Bogdan Udrea

This paper presents the concept of operations and preliminary design of a multi-satellite mission for the active removal of large pieces of debris from low Earth orbit. The mission consists of a mothership minisatellite, that carries six nanosatellites. The mothership acquires a relative orbit of a few kilometers with respect to the piece of orbital debris of interest and determines the attitude state of the debris and good docking locations for the nanosatellites. The nanosatellites deploy sequentially and dock with the piece of debris. Once all the nanosatellites are docked with the debris they cooperatively perform its structural analysis to determine safe maneuvering profiles for its detumble and deorbit. The mothership then docks with the piece of debris and applies maneuvers to deorbit it. Systems engineering budgets have been determined for the mass and propellant and a preliminary mission cost has been estimated. They are presented together with the functional architectures of each spacecraft and the results of mission design obtained with the Systems Tool Kit.
 


A laser-optical system to re-enter or lower low Earth orbit space debris
Location:
Photonic Associates, LLC
Investigator:
Claude R. Phipps
Duration:
2014

Collisions among existing Low Earth Orbit (LEO) debris are now a main source of new debris, threatening future use of LEO space. Due to their greater number, small (1–10 cm) debris are the main threat, while large (>10 cm) objects are the main source of new debris. Flying up and interacting with each large object is inefficient due to the energy cost of orbit plane changes, and quite expensive per object removed. Strategically, it is imperative to remove both small and large debris. Laser-Orbital-Debris-Removal (LODR), is the only solution that can address both large and small debris. In this paper, we briefly review ground-based LODR, and discuss how a polar location can dramatically increase its effectiveness for the important class of sun-synchronous orbit (SSO) objects. With 20% clear weather, a laser-optical system at either pole could lower the 8-ton ENVISAT by 40 km in about 8 weeks, reducing the hazard it represents by a factor of four. We also discuss the advantages and disadvantages of a space-based LODR system. We estimate cost per object removed for these systems. International cooperation is essential for designing, building and operating any such system.


A reorbiter for large GEO debris objects using ion beam irradiation
Location:
Hosei University, Japan Aerospace Exploration Agency
Investigator:
Shoji Kitamura, Yukio Hayakawa, Satomi Kawamoto
Duration:
2012-13

In recent years, space debris problems have become very serious. The worst case occurs in the low Earth orbit (LEO) region, where debris-to-debris collisions generate new debris. The situation in the geostationary orbit (GEO) region is not as bad as that in the LEO. The debris problem in the GEO region, however, should not be left as it is because the GEO is unique and has few debris-cleansing modes. Thus, we proposed a concept for a reorbiter to reorbit large GEO debris objects such as satellites and rocket upper stages left in orbit after the ends of their missions. This concept is based on the idea of thrusting a debris object by irradiating it with an ion beam. The reorbiter, equipped with two ion engines, approaches a debris object, and the ion beam exhausted from one of the ion engines irradiates and thrusts it to change its orbit. The other engine on the opposite side is operated so that the reorbiter follows the debris object. Their orbits are raised in a spiral to a disposal orbit approximately 300 km higher. After that, the reorbiter returns to GEO to approach another debris object. This system can operate without catching debris objects; thus, it can be applied to a wide range of debris objects without regard to their shapes or rotations. A mission scenario was made to conduct efficient maneuvers. In the GEO region, a number of debris objects are distributed on orbit planes close to each other, and they can be reorbited one after another using a single reorbiter. For a typical model mission, the mission time and the total impulse of the ion engines were calculated. The results show that six debris objects can be reorbited in 170 days. The reorbiter has a targeted launch mass of 2500 kg and 6.9 kW of total power. The ion beam convergence, the effects of ion beam irradiation, and non-cooperative rendezvous were recognized as the critical issues of this system. A highly converged beam is required to make efficient debris irradiation. Numerical calculations and basic experiments gave a feasibility of the required irradiation efficiency of over 25%. The irradiation of debris objects may cause sputtering of their surfaces and depositions of the back-sputtered materials on the reorbiter surface. The data were obtained experimentally to evaluate the effects of the depositions, especially on solar cells. The results indicated no serious contamination problems. Preliminary studies were conducted on the approach to an uncollaborative object and the maintenance of the separation distance.


A review of space robotics technologies for on-orbit servicing
Location:
New Mexico State University, USAF Research Laboratory
Investigator:
Angel Flores-Abad, Ou Ma, Khanh Pham, Steve Ulrich
Duration:
2013-2014

Space robotics is considered one of the most promising approaches for on-orbit servicing (OOS) missions such as docking, berthing, refueling, repairing, upgrading, transporting, rescuing, and orbital debris removal. Many enabling techniques have been developed in the past two decades and several technology demonstration missions have been completed. A number of manned on-orbit servicing missions were successfully accomplished but unmanned, fully autonomous, servicing missions have not been done yet. Furthermore, all previous unmanned technology demonstration missions were designed to service cooperative targets only. Robotic servicing of a non-cooperative satellite is still an open research area facing many technical challenges. One of the greatest challenges is to ensure the servicing spacecraft safely and reliably docks with the target spacecraft or capture the target to stabilize it for subsequent servicing. This is especially important if the target has an unknown motion and kinematics/dynamics properties. Obviously, further research and development of the enabling technologies are needed. To motivate and facilitate such research and development, this paper provides a literature review of the recently developed technologies related to the kinematics, dynamics, control and verification of space robotic systems for manned and unmanned on-orbit servicing missions.


Active removal of orbital debris by induced hypervelocity impact of injected dust grains
Location:
Naval Research Lab, Icarus Research Co.
Investigator:
G. Ganguli, C. Crabtree, A. Velikovich, L. Rudakov, S. Chappie
Duration:
2014

Collisions of an active satellite with a small (1mm – cm) untrackable orbital debris can be mission ending. It has been recently established that we are at the tipping point for collisional cascade of larger objects to exponential growth of small orbital debris. This will make access to near-Earth space hazardous without first clearing the existing debris from this region. We present a concept for elimination of small debris by deploying micron scale dust to artificially enhance the drag on the debris. The key physics that makes this technique viable is the possibility of large momentum boost realized through hypervelocity dust/debris collision. By deploying high mass density micron scale dust in a narrow altitude band temporarily it is possible to artificially enhance drag on debris spread over a very large volume and force rapid reentry. The injected dust will also reenter the atmosphere leaving no permanent residue in space.


Active space debris charging for contactless electrostatic disposal maneuvers
Location:
University of Colorado, Boulder
Investigator:
Hanspeter Schaub, Zoltan Sternovsky
Duration:
2013

The remote charging of a passive object using an electron beam enables touchless re-orbiting of large space debris from geosynchronous orbit (GEO) using electrostatic forces. The advantage of this method is that it can operate with a separation distance of multiple craft radii, thus reducing the risk of collision. The charging of the tug–debris system to high potentials is achieved by active charge transfer using a directed electron beam. Optimal potential distributions using isolated- and coupled-sphere models are discussed. A simple charging model takes into account the primary electron beam current, ultra-violet radiation induced photoelectron emission, collection of plasma particles, secondary electron emission and the recapture of emitted particles. The results show that through active charging in a GEO space environment high potentials can be both achieved and maintained with about a 75% transfer efficiency. Further, the maximum electrostatic tractor force is shown to be insensitive to beam current levels. This latter later result is important when considering debris with unknown properties.


Advanced research network on asteroid and space debris manipulation
Location:
Stardust
Investigator:
Prof. Dr. Massimiliano Vasile
Duration:
February 2013 - February 2017

Stardust is a unique training and research network devoted to develop and master techniques for asteroid and space debris monitoring, removal/deflection and exploitation, with the following specific aims: training the next generation of engineers, scientists and decision-makers to protect our planet, save our space assets, and turn the threat represented by asteroids and space debris in an opportunity; pushing the boundaries of space research with innovative ideas and visionary concepts; integrating multiple disciplines, from robotics, to applied mathematics, from computational intelligence to astrodynamics, to find practical and effective solutions to the asteroid and space debris issue.


An adaptive strategy for active debris removal
Location:
University of Southhampton
Investigator:
Adam E. White, Hugh G. Lewis
Duration:
2013-2014

Many parameters influence the evolution of the near-Earth debris population, including launch, solar, explosion and mitigation activities, as well as other future uncertainties such as advances in space technology or changes in social and economic drivers that effect the utilisation of space activities. These factors lead to uncertainty in the long-term debris population. This uncertainty makes it difficult to identify potential remediation strategies, involving active debris removal (ADR), that will perform effectively in all possible future cases. Strategies that cannot perform effectively, because of this uncertainty, risk either not achieving their intended purpose, or becoming a hindrance to the efforts of spacecraft manufactures and operators to address the challenges posed by space debris. One method to tackle this uncertainty is to create a strategy that can adapt and respond to the space debris population. This work explores the concept of an adaptive strategy, in terms of the number of objects required to be removed by ADR, to prevent the low Earth orbit (LEO) debris population from growing in size. This was demonstrated by utilising the University of Southampton’s Debris Analysis and Monitoring Architecture to the Geosynchronous Environment (DAMAGE) tool to investigate ADR rates (number of removals per year) that change over time in response to the current space environment, with the requirement of achieving zero growth of the LEO population. DAMAGE was used to generate multiple Monte Carlo projections of the future LEO debris environment. Within each future projection, the debris removal rate was derived at five-year intervals, by a new statistical debris evolutionary model called the Computational Adaptive Strategy to Control Accurately the Debris Environment (CASCADE) model. CASCADE predicted the long-term evolution of the current DAMAGE population with a variety of different ADR rates in order to identify a removal rate that produced a zero net growth for that particular projection after 200 years. The results show that using an adaptive ADR rate generated by CASCADE, alongside good compliance with existing mitigation measures, increases the probability of achieving a constant LEO population of objects greater than 10 cm. This was shown to be 12% greater compared with removing five objects per year, with the additional advantage of requiring only 3.1 removals per year, on average.


Analysis of tape tether survival in LEO against orbital debris
Location:
Department of Applied Physics, Escuela Tecnica Superior de Ingenieros Aeronauticos
Investigator:
Shaker Bayajid Khan, Juan R. Sanmartin
Duration:
2013-2014

The low earth orbit (LEO) environment contains a large number of artificial debris, of which a significant portion is due to dead satellites and fragments of satellites resulted from explosions and in-orbit collisions. Deorbiting defunct satellites at the end of their life can be achieved by a successful operation of an Electrodynamic Tether (EDT) system. The effectiveness of an EDT greatly depends on the survivability of the tether, which can become debris itself if cut by debris particles; a tether can be completely cut by debris having some minimal diameter. The objective of this paper is to develop an accurate model using power laws for debris-size ranges, in both ORDEM2000 and MASTER2009 debris flux models, to calculate tape tether survivability. The analytical model, which depends on tape dimensions (width, thickness) and orbital parameters (inclinations, altitudes) is then verified with fully numerical results to compare for different orbit inclinations, altitudes and tape width for both ORDEM2000 and MASTER2009 flux data.


Design and Analysis Tools for Deployable Solar Array Systems
Location:
ATA Engineering
Investigator:
Dr. Cory Rupp
Duration:
May 2014 - May 2016

Game-changing space exploration and debris remediation technologies, such as solar electric propulsion (SEP), will necessitate solar array systems  and other deployable structures orders of magnitude larger than current designs - requiring new ways to design, analyze, and test these unprecedented structures. This project will develop a software toolset for rapid model creation, analysis, deployment simulation, and parametric studies of next-generation solar array systems. It will enable engineers to make early-stage design decisions with only a fraction of the resource required for explicit modeling and detailed simulation.


Pages

An Economic Analysis of Earth Orbit Pollution
Location:
Purdue University, FCC, Naval Academy
Investigator:
Nodir Adilov , Peter J. Alexander, Brendan M. Cunningham
Duration:
2014

Space debris, an externality generated by expended launch vehicles and damaged satellites, reduces the expected value of space activities by increasing the probability of damaging existing satellites or other space vehicles. Unlike terrestrial pollution, debris created in the production process interacts with firms’ final products, and is, moreover, self-propagating: collisions between debris or extant satellites creates additional debris. We construct a formal model to explore private incentives to launch satellites and to mitigate space debris. The model predicts that, relative to the social optimum, firms launch too many satellites and choose technologies which create more debris than is socially optimal. We discuss remediation strategies and policies, and demonstrate that Pigovian taxes can be used to internalize the debris externality.


An Inference about Interference: A Surprising Application of Existing International Law to Inhibit Anti-Satellite Weapons
Location:
Georgetown University
Investigator:
David A. Koplow
Duration:
2014

This article presents a thesis that most readers will find surprising, in an effort to develop a novel, simultaneous solution to three urgent, complex problems related to outer space. The three problems are: a) the technical fact that debris in outer space (the accumulated orbital junk produced by decades of space activities) has grown to present a serious hazard to safe and effective exploration and exploitation of space; b) the strategic fact that many countries (notably the United States, China and Russia, but others, too) continue to demonstrate a misguided interest in pursuing anti-satellite weapons, which can jeopardize the security of space; and c) the political fact that attempts to provide additional legal regulation of outer space (via new bilateral or multilateral international agreements) have failed, with little prospect for prompt conclusion of meaningful new accords.

 

The proposed solution is to adapt existing international law in an unforeseen way. Specifically, numerous current and historical arms control treaties provide for verification of parties’ compliance via “national technical means” (NTM) of verification, which prominently include satellite-based sensory and communications systems. These treaties routinely provide protection for those essential space assets by requiring parties to undertake “not to interfere” with NTM. The argument developed here is that additional tests in space of debris-creating anti-satellite weapons would already be illegal, even without the conclusion of any dedicated new treaty against further weaponization of space, because in the current crowded conditions of space, a new cloud of orbital debris would, sooner or later, impermissibly interfere with NTM satellites.

 

If sustained, this thesis can provide a new rationale for opposition to the development, testing, and use of anti-satellite weapons. It a legal reinforcement for the political instincts to avoid activities that further undercut the optimal usability of outer space, and it demonstrates how creative re-interpretation of existing legal provisions can promote the advancement of the rule of international law, even in circumstances where the articulation of new treaties is blocked.


Cascading Crises: Orbital Debris and the Widening of Space Security
Location:
Aberystwyth University
Investigator:
Bleddyn E. Bowen
Duration:
2014

The term space security is often used, but seldom analyzed. This is a significant gap in the literature of space politics, as it posits considerable implications for debates on how to deal with a runaway growth in the space debris population, and how we argue for or against space weaponization. Securitizing all threats in space may lead to greater difficulties in enacting debris removal measures, as these systems are inherently dual-use. A case is made for keeping space security in its traditional connotations of national security so that environmental issues related to orbital debris can be resolved with reduced security concerns in a space development framing.


Competition and Collaboration in Space between the U.S., China, and Australia: Woomera to WGS and the Impact of Changing U.S. National Space Security Policy
Location:
RAND Corporation
Investigator:
Chad J. R. Ohlandt
Duration:
2014

U.S. national security space policy has recently shifted significantly toward increased international cooperation. Australian space activities have been reinvigorated, but remain underfunded. China’s space activities remain vigorous, but largely unilateral. Given U.S. policy changes, opportunities for cooperation and collaboration among all three have improved.


Compliance of disposal orbits with the French Space Operations Act: The Good Practices and the STELA tool
Location:
CNES
Investigator:
C. Le Fèvre, H. Frayssea, V. Morand, A. Lamy, C. Cazaux, P. Mercier, C. Dental, F. Deleflie, D.A. Ha
Duration:
2013

Space debris mitigation is one objective of the French Space Operations Act (FSOA), in line with Inter-Agency Space Debris Coordination Committee (IADC) recommendations, through the removal of non-operational objects from populated regions. At the end of their mission, space objects are to be placed on orbits that will minimize future hazards to space objects orbiting in the same region. The FSOA, which came into force in 2010, ensures that technical risks associated with space activities are properly mitigated. The Act confers CNES a central support role in providing technical expertise to government on regulations dealing with space operations. In order to address the compliance of disposal orbits with the law technical requirements, CNES draws up Good Practices as well as a dedicated tool, Semi-analytic Tool for End of Life Analysis (STELA).

 

The verification of the criteria of the French Space Operations Act requires long term orbit propagation to evaluate the evolution of the orbital elements over long time scales (up to more than 100 years). The Good Practices define the minimum dynamical model required to compute the orbital evolution with sufficient accuracy, and detail key computation hypotheses such as drag and reflecting areas, drag coefficient, reflectivity coefficient, solar activity, atmospheric density model and so on. They also recommend a methodology adapted to each orbit type (LEO, GEO, GTO) to assess the criteria of the French Space Operations Act. The most recent works have concerned GTO, for which some couplings occur between dynamic perturbations. A small change in the initial conditions or in the estimation of the drag effect will significantly change the entrance conditions in resonance areas and thus the orbital evolution. To cope with this difficulty, a statistical method has been developed.

 

This paper gives an overview of the Good Practices for orbit propagation in LEO, GEO and GTO as well as a brief description of the STELA tool. It explains the specificities of GTO and the need for a statistical approach, through a Monte-Carlo campaign of orbital propagations. Then, it raises the question of the statistical convergence and proposes a methodology to estimate a confidence interval for the results. Finally, special cases consisting of typical GTO are treated.


Confronting Space Debris
Location:
RAND Corporation
Investigator:
Dave Baiocchi, William Welser IV
Duration:
2010

Orbital debris represents a growing threat to the operation of man-made systems in space. There are currently hundreds of thousands of debris objects greater than one centimeter in diameter in Earth's orbit, and the collision of any one of these objects with an operational satellite would cause catastrophic failure of that satellite. The authors identified a set of comparable problems that share similarities with orbital debris and narrowed this set down to the following nine issues: acid rain, U.S. commercial airline security, asbestos, chlorofluorocarbons, hazardous waste, oil spills, radon, email spam, and U.S. border control. This monograph provides context and insight for decisionmakers by asking the following questions: How have other industries approached their "orbital debris-like" risks? What lessons can be learned from these cases before proceeding with debris mitigation or remediation measures? Findings are drawn from practical examples that include the Deepwater Horizon oil spill, the results of which emphasized that remedies must be designed and tested to work under the actual operating conditions.


Developments in Space Policies, Programmes and Technologies Throughout the World and in Europe
Location:
ESPI
Investigator:
Cenan Al-Ekabi
Duration:
2013

All major space policy developments worldwide were presented in the previous section of Chap. 1, in an attempt to clarify the principal space faring nations’ strategies in 2011 and 2012. In the section below, there will be a brief discussion on developments in technology related areas, including policies and access to space technologies. The aim of this section is to clarify how the above presented strategies interact with and influence specific space programmes, and related research and development projects.


Investigation of national policy shifts to impact orbital debris environments
Location:
University of Alabama
Investigator:
Thomas K. Percy, D. Brian Landrum
Duration:
2013

Low earth orbit has become increasingly congested as the satellite population has grown over the past few decades, making orbital debris a major concern for the operational stability of space assets. This congestion was highlighted by the collision of the Iridium 33 and Cosmos 2251 satellites in 2009. This paper addresses the current state of orbital debris regulation in the United States and asks what might be done through policy change to mitigate risks in the orbital debris environment. A brief discussion of the nature of orbital debris addresses the major contributing factors including size classes, locations of population concentrations, projected satellite populations, and current challenges presented in using post-mission active debris removal to mitigate orbital debris. An overview of the current orbital debris regulatory structure of the United States reveals the fragmented nature of having six regulating bodies providing varying levels of oversight to their markets. A closer look into the regulatory policy of these agencies shows that, while they all take direction from The U.S. Government Orbital Debris Mitigation Standard Practices, this policy is a guideline with no real penalty for non-compliance. Various policy solutions to the orbital debris problem are presented, ranging from a business as usual approach to a consolidated regulation system which would encourage spacecraft operator compliance. The positive aspects of these options are presented as themes that would comprise an effective policy shift towards successful LEO conservation. Potential economic and physical limitations to this policy approach are also addressed.


Legality of Anti-Satellites Under the Space Law Regime
Location:
National University of Juridical Sciences, Kolkata, India
Investigator:
Promit Chatterjee
Duration:
2014

The term anti-satellite, or in short ASAT, is used to refer to a system designed to destroy or damage satellites. The heightened tendency among the spacefaring nations to develop ASAT technology in the recent past has led to widespread debates as to the legality of ASAT deployment under the space law regime. In this context, I have endeavored to make a detailed analysis of the international legal provisions to find if there is any legal basis at all for the deployment of such ASATs. I have concluded that none of the existing legal provisions in space law, as well as public international law, have sufficient force and clarity to bring about a blanket ban on ASAT weapons. Therefore, the research suggests a slew of reforms to overcome this anomaly. Examples of such proposed reforms include, inter alia, an amendment of the Outer Space Treaty and an enhanced role and influence of the United Nations in treaty making coupled with active diplomatic initiatives.


Orbital sprawl, space debris and the geostationary ring
Investigator:
Patricia M. Sterns, Leslie I. Tennen
Duration:
2003

Contamination of outer space by debris and non-functional objects presents a significant challenge to scientists, mission planners and jurists. A continuation of present activities will result in a condition of orbital sprawl whereby certain orbits, notably the geostationary ring, will become saturated with such objects, forcing the location of spacecraft at a distance from the optimal slot and posing a growing risk of collision. This article considers ways in which the law of outer space might provide an effective framework for responding to the growth and changing character of space activities.


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