Small Orbital Debris Research Articles

On Ion-Acoustic Precursor Soliton Signatures of Orbital Debris in Low Earth Orbit

Nonlinear plasma solitons have been recently proposed as a possible, indirect way to detect dangerous small orbital debris in low Earth orbit. A kinetic simulation study of the interaction between small debris flowing through a plasma at hypersonic velocity is presented, with a particular focus on whether the debris–plasma interaction leads to the formation of ion-acoustic precursor solitons. By using an electrostatic kinetic model and in the absence of an external magnetic field, simulation results where the debris is treated as a Gaussian density source are compared with those where the debris–plasma interaction is modeled self-consistently, in both one and two dimensions. While ion-acoustic solitons are formed when the debris is treated as a Gaussian density source and the ions are cold, it is shown that self-consistent debris charging with similar parameters hinders the formation of precursor solitons. This indicates that self-consistent debris charging is key to quantitative predictions of soliton formation. Additionally, when the ion and electron temperatures are comparable, as typical of conditions in low Earth orbit, Landau damping physics also hinders the formation of ion-acoustic precursor solitons. These results suggest that it will be challenging to exploit ion-acoustic precursor solitons for orbital debris detection in low Earth orbit.

On-orbit optical detection of lethal non-trackable debris

Resident space objects in the size range of 0.1 mm–3 cm are not currently trackable but have enough kinetic energy to have lethal consequences for spacecraft. The assessment of small orbital debris, potentially posing a risk to most space missions, requires the combination of a large sensor area and large time coverage. For example, a sensor with a time•area product of 3 m2-years is considered sufficient to make a significant contribution to our understanding of the near-Earth small debris population. Deploying large sensors, however, is generally resource intensive, due to their size and weight. The lightsheet sensor concept, allows the creation of a “virtual witness plate”, which is created without any supporting physical structure and therefore presents an attractive opportunity for the detection small debris anywhere between low Earth orbit and interplanetary space. This sensor project is called Lightsheet Anomaly Resolution And Debris Observation (LARADO). Recent technology maturation efforts in the laboratory have successfully detected small debris (1.6 mm diameter) moving at 6.38 km/s. NRL is building the NASA funded the LARADO instrument as a technology maturation effort for a flight demonstration on STPSat-7 in 2025. In this presentation, we will describe the LARADO instrument, present the laboratory data and analysis, and describe the instrument details for the STPSat-7 spacecraft slated for launch via the DoD Space Test Program in CY2025.

Analysis of hypervelocity-impacted thin films for space applications

Exposure to the harsh space environment and hypervelocity impacts from micrometeoroids and small orbital debris can affect space operations through long-term degradation of spacecraft materials, surfaces, or systems. Multi-layer insulation (MLI) and coated polyimide films are spacecraft materials commonly found on the external surfaces of spacecraft for thermal control and protection. Characterizing the damage to these exposed materials with in situ and laboratory measurements can better inform spacecraft designers and operators in understanding and mitigating surface or system degradation. In this paper, we examine flown Hubble Space Telescope (HST) Equipment Bay 5 MLI and coated polyimide hypervelocity ground tested articles to characterize hypervelocity impact damage. Impact feature cavities are inspected to identify damage, which can validate long-term degradation models, improve thermal management systems, or improve accuracy of damage predictions. An overview of the impact characterization using optical microscopy, narrow-band spectroscopy, and Scanning Election Microscopy/Energy Dispersive X-ray (SEM/EDX) of the two materials is presented. Observations of robustness in the space environment, as well as a detailed assessment of cratering and penetration statistics for the space-exposed sample, are also discussed.

The small orbital debris population and its impact on space activities and ecological safety

When it is said about the danger of orbital debris for space activities and the ecology of the Earth, it most often means large orbital debris. In contrast to large orbital debris, the influence of small ones to space activities and ecology of the Earth and near-Earth space is often underestimated. As will be shown in this paper, it is unfair. New data on the dynamics of contamination of near-Earth space with small debris in low Earth orbit were obtained. The number, mass, and dynamics of the small orbital debris population in low Earth orbit are estimated as well as the consequences of the deployment of multi-satellite communication satellite systems are estimated. It makes the study of this area particularly relevant. The various aspects of the consequences of technogenic contamination of near-Earth space are considered. The comparison of the danger of small orbital particles and large satellite fragments for space activity and the ecology of the Earth and near-Earth space is also provided. А significant lack of reliable information on small space debris is proved to be one of the main limiting factors for our knowledge about the population of space debris in low Earth orbits.

Generalized Polynomial Chaos Expansion Approach for Uncertainty Quantification in Small Satellite Orbital Debris Problems

This paper demonstrates the use of generalized polynomial chaos expansion for the propagation of uncertainties present in various dynamical models. Specifically, a sampling based non-intrusive approach using pseudospectral stochastic collocation is employed to obtain the coefficients required for the generalized polynomial chaos expansion. Various recently developed quadrature techniques are employed within the generalized polynomial chaos expansion framework in order to illustrate their efficacy. In addition to that, the paper also provides an efficient numerical quadrature technique to be used as a sampling technique in stochastic collocation to quantify the uncertainties which are governed by different distribution functions. Results are presented for the orbital motion of a 2U CubeSat subject to initial condition uncertainty and drag related parametric uncertainty demonstrating the accuracy and effectiveness of the proposed technique. Further, stochastic sensitivity analysis is performed to gain insight into the impact of uncertain variables on the evolution of the quantities of interest.

Fragmentation of Millimeter-Size Hypervelocity Projectiles on Combined Mesh-Plate Bumpers

This numerical study evaluates the concept of a combined mesh-plate bumper as a shielding system protecting unmanned spacecraft from small (1 mm) orbital debris impacts. Two-component bumpers consisting of an external layer of woven mesh (aluminum or steel) directly applied to a surface of the aluminum plate are considered. Results of numerical modeling with a projectile velocity of 7 km/s indicate that, in comparison to the steel mesh-combined bumper, the combination of aluminum mesh and aluminum plate provides better fragmentation of small hypervelocity projectiles. At the same time, none of the combined mesh/plate bumpers provide a significant increase of ballistic properties as compared to an aluminum plate bumper. This indicates that the positive results reported in the literature for bumpers with metallic meshes and large projectiles are not scalable down to millimeter-sized particles. Based on this investigation’s results, a possible modification of the combined mesh/plate bumper is proposed for the future study.

Engineering enhanced cut and puncture resistance into the thermal micrometeoroid garment (TMG) using shear thickening fluid (STF) – Armor™ absorber layers

The low-earth orbit environment contains small micrometeoroid and orbital debris (MMOD) particles traveling at characteristic velocities of several kilometers per second. In addition to being a direct threat to astronauts and spacecraft, upon impact with the exterior surface of a space vehicle, these highly energetic MMOD particles can create cut and puncture hazards for astronauts performing extra-vehicular activities (EVA). In this work, we demonstrate that replacing the standard neoprene-coated nylon absorber layers with woven aramid textiles intercalated with colloidal shear thickening fluids, i.e., STF-Armor™, can provide a meaningful enhancement to the cut and puncture resistance of the thermal micrometeoroid garment (TMG). Quasi-static puncture testing is performed using hypodermic needles of varying gauge to simulate the cutting and puncture hazards at deformation rates characteristic of human motion. At equal areal densities, we find that a TMG lay-up containing STF-Armor™ greatly improves puncture protection with a reduction in weight and comparable flexibility.

A Concept for Elimination of Small Orbital Debris

A concept for forced reentry of small orbital debris with characteristic dimension ~ 10 cm from the highly populated sun synchronous orbit by injecting micron scale dust grains to artificially enhance drag is discussed. The drag enhancement is most effective when dust grains counter rotate with respect to the debris resulting in hypervelocity dust/debris impacts. While the natural drag on small debris with ballistic coefficient ~ 5 kg/m2 in orbits with perigee above 900 km is negligible, it is sufficient to decay the orbit of the injected dust grains at a significant rate. This offers a unique opportunity to synchronize the rates of descent of the dust and debris to create a sweeping (snow-plow-like) effect on the debris by a descending narrow dust layer. The dust density necessary to de-orbit small debris is sufficiently low such that the orbits of active satellites which have larger ballistic coefficients are minimally affected. If deemed necessary, contact of the injected dust with active satellites may be avoided by maneuvering the satellite around the narrow dust layer.

Are de-orbiting missions possible using electrodynamic tethers? Task review from the space debris perspective

Over 9000 satellites and other trackable objects are currently in orbit around the Earth, along with many smaller particles. As the low Earth orbit is not a limitless resource, some sort of debris mitigation measures are needed to solve the problem of unusable satellites and spent upper stages. De-orbiting devices based on the use of conducting tethers have been recently proposed as innovative solutions to mitigate the growth of orbital debris. However, electrodynamic tethers introduce unusual problems when viewed from the space debris perspective. In particular, because of their small diameter, tethers of normal design may have a high probability of being severed by impacts with relatively small meteoroids and orbital debris. This paper compares the results obtained at ISTI/CNR, the Kyushu University and NASA/JSC concerning the vulnerability to debris impacts on a specific conducting tether able to de-orbit spacecraft in inclinations up to 75 ∘ and initial altitude less than 1400 km. A double line tether design has been analyzed, in addition to the single wire solution, in order to reduce the tether vulnerability. The results confirm that the survivability concern is fully justified for a single line tether and no de-orbit mission, from the altitudes and inclinations considered, is possible if the tether diameter is smaller than a few millimeters. The survival probability is shown to grow for a double line configuration with a sufficiently high number of knots and loops. The results are strongly dependent on the environment model adopted and the MASTER-2001 orbital debris and meteoroids fluxes result in survival probabilities appreciably higher than those of ORDEM2000 coupled with the Grün meteoroids model.

Contribution of secondary ejecta to the debris population

When a micro-debris or a micrometeoroid impacts a spacecraft surface, secondary particles, called ejecta, are produced. These ejecta can contribute to a modification of the debris environment: either locally by the occurrence of secondary impacts on the components of complex and large space structures, or at great distances by the formation of a population of small orbital debris. This paper describes the ejecta production mechanism, and shows their orbital evolution. Then, the distribution of ejecta in low earth orbits is given. Some results are presented describing the number of ejecta as a function of size and altitude.

Modelling of Ejecta as a Space Debris Source

When a micro-debris or a micrometeoroid impacts a spacecraft surface, a large number of secondary particles, called ejecta, are produced. These particles can contribute to a modification of the debris environment: either locally by the occurrence of secondary impacts on the components of complex and large space structures, or at great distance by the formation of a population of small orbital debris. This paper describes firstly, the ejecta overall production, and secondly, the lifetime and the orbital evolution of the particles. Finally the repartition of ejecta in LEO is computed. Some results describing the population as a function of size and altitude are presented.

A space based radar on a micro-satellite for in-situ detection of small orbital debris

The increase in the number of satellites in the Near Earth Orbit is exponential. The consequent increase in pollution of the orbital environment is of growing concern to the international community. There are currently only two observation systems available for measurement of orbital debris. Ground based radar and telescopes can detect objects larger than about 7 cm. Passive space based systems provide an accurate statistical estimation of flux for debris smaller than about 0.1 mm in size. Consequently, there is no way of obtaining information about debris in the millimeter-size range. Considering that the relative speed between objects in space is commonly in the km/s range, millimeter sized debris carry enough energy to be deadly to astronauts or to totally destroy the functioning of any satellite. Then National space agencies have recommended launching orbital spacecraft carrying debris detection experiments for gaining a better understanding of small debris. CNES (the French Space Agency) is developing a new family of micro-satellites, that will make possible to put into orbit a totally new system of radar that could measure in-situ flux of debris. We present results of this system analysis, which would cumulate the advantages of both ground-based radar and in orbit passive experiments. The proposed method for detection is quite original and allows the radar to act like a band-pass filter with respect to the debris diameter. The optimum frequency is shown to be in the Ka-band. Two points are critical in the definition of the radar: the average power available and the false alarm probability in the detection criterion. Therefore, we present a special receiver chain in order to optimize the signal-to-noise ratio. The estimate of the radial velocity through Doppler frequency measurement may be used to discriminate orbital debris from meteoroids. This system could be built today using an existing Continuous Wave amplifier. Several hundreds of objects per year could be detected yielding an accurate statistical estimation. The orbital debris radar would be a major contribution to our knowledge of millimeter sized debris. This experiment would contribute to making the current models more accurate at all inclinations. The micro-satellite concept would make the orbital debris radar mission cheap enough for considering a constellation of such satellites.

The importance of nonfragmentation sources of debris to the environment

Historically, satellite fragmentation has been assumed to be the major source of small orbital debris, based on U.S. Space Command observations. Although it was always known that only a few tens of kilograms of small debris could produce a significant debris hazard, there was no hard evidence that any space operations were releasing even these small quantities. Recent observations of small debris have led to the discovery of numerous nonfragmentation sources; in some cases, these sources have produced a hazard that exceeds the hazard from satellite breakups. In the centimeter-size range, these findings include aluminum oxide slag from solid rocket motors, sodium potassium droplets from coolant systems, and copper needles from U.S. experiments. Smaller debris include paint flecks from spacecraft surfaces and aluminum oxide dust from solid rocket motors. Since the number of known debris sources seems to be proportional to the amount of effort expended looking for new sources and since observation programs to measure the small debris environment have just begun, many more sources are likely to be identified. These nonfragmentation sources could increase the need for mitigation efforts and complicate cost/benefit analyses of current efforts.

Liquid metal mirror for optical measurements of orbital debris

A telescope employing a liquid metal (mercury) mirror that is three meters in diameter was developed for the purpose of measuring the population of small orbital debris. The telescope is installed at a 9,000 ft site in the mountains of New Mexico at a latitude of 32.98 degrees, and has completed final optical performance tests. A Ford 2048 × 2048 CCD detector is used at the image plane. With this detector, the limiting stellar magnitude of the telescope was measured to be 23 at a S/N of about 3, with a nominal full width, half maximum for stellar images of 1.3 arcsec. Safety problems with toxic mercury vapor were minimal at operating temperatures below 60 F, greatly simplifying operations with the mirror. Performance of the telescope for debris at geosynchronous orbit (GEO) altitudes is estimated to be in the range 5 to 10 cm using the existing CCD detector. However, at its present location in New Mexico, the telescope cannot be used for detection of debris in the GEO region, since it cannot see debris with inclinations below 32 degrees. Performance of the telescope for debris in low earth orbit depends on the kind of detector that is used. Efforts were made to use the CCD detector for fast-moving low earth orbit debris by reading out the detector at the same rate and in the same direction as the debris object crosses the field of view of the telescope. In this mode, the telescope was capable of detecting debris as small as 3 centimeters at 900 km altitude. However, this mode is very inefficient, since debris moving in other directions is not detected. Observations have also been done using an intensified CCD video camera as the detector. The limiting detectable size for this detector was about 4 centimeters at 500 km, and 7 centimeters at 1000 km. A design was developed for the optimum detector for fast-moving debris in low earth orbit based on currently available technology. This is a 1024×1024 element CCD detector operating at 200 frames per second, with pixels binned to 16×16. This detector should be capable of detecting 1 cm debris at 500 km and 1.5 cm debris at 1000 km. New data processing algorithms will be required to process the data stream from this detector.

Liquid metal mirror for optical measurements of orbital debris

A telescope employing a liquid metal mirror that is three meters in diameter has been developed for the purpose of measuring the population of small orbital debris. The telescope has been installed at a location in the mountains of New Mexico, and is undergoing final engineering tests. The limiting stellar magnitude of the telescope has been measured to be 21.5, with resolution of 1.8 arcsec. The highest sensitivity for orbital debris detection is achieved by reading out the CCD detector at the same rate and in the same direction as the debris object crosses the field of view of the telescope. In this mode, the telescope is capable of detecting debris as small as 2.5 centimeters at 900 km altitude, and less than 10 centimeters at geosynchronous altitudes. Improved performance for LEO altitudes might be achieved by the use of fast readout detectors.

From LDEF to EURECA: Orbital debris and meteoroids in low earth orbit

Many human operations have created a large population of small orbital debris in near Earth environment. The threat they represent for satellites is a major factor for the preparation of future space missions. Several experiments devoted to the study of this environment, as well as various materials exposed to space, have been retrieved in the past few years. The analysis of the results shows some differences with previous modeling. Comparison with data from LDEF and from EURECA give some insight in the long term evolution of particle size distribution. Chemical identification of particle remnants inside craters is difficult but provides valuable information on the origin of the impactors. Permanent monitoring of environment is obviously needed, especially for the type of orbits where data are presently scarce ie. heliosynchronous and geostationary orbits.

Orbital debris removal by laser radiation

The use of high-power lasers is suggested for removing small dangerous orbital debris up to about 10 cm in diameter. Assuming data for a most probable collision orbit and for realistic ejection speeds of debris vapor under laser irradiation, calculations show the feasibility of treating a debris object like a laser propelled rocket. The acceleration of the debris during irradiation allows to change its orbit for a direct re-entry into the atmosphere of the earth or for escape from earth's gravitational field. Only a fraction of the laser power would be needed compared to that for complete vaporization of the debris. An autonomous orbital vehicle equiped with a moderately sized laser, proper optics and the instrumentation for the acquisition and tracking of debris objects could eventually clear the whole low earth orbital environment from small debris. In a modification of this method a laser could be used on short note to divert the flight path of a piece of debris to avoid a collision. The principal of the underlying mechanism is shown in a simple experiment.