Space debris detection
2017, 46(7): 729001.
doi: 10.3788/IRLA201746.0729001
The existence of space debris has been causing great threats to the security of spacecraft in orbit. Space debris will occupy the limited and precious orbit capacities, so more and more debris generated in the space will also be a huge threat. The real-time high precision orbit determination of debris based on laser ranging technology can effectively avoid the collision between the debris and the spacecraft. In order to make high precision laser ranging to small size space debris, the 53 cm diameter binocular was developed here, which was capable of fast and steady tracking space targets of 400 km above the ground. Combined with low-power high-repetition-rate sub-nanosecond laser generator and single photon detecting technology, the space debris laser ranging technique was implemented on this binocular telescope. According to the laser ranging formulas, the detecting capability of this space debris laser ranging system was researched and analyzed. When the space debris was 1 000 km away from the ground station, the minimum size of the echo photon which can be detected is about 478.5 cm. This space debris laser ranging system has been putting into observation, and the practical observation results indicate this system has the capability to detect meter level debris in ca. 1 000 km distance.
2017, 46(3): 329001.
doi: 10.3788/IRLA201746.0329001
High precise measurement of space debris is an important way to improve the precise surveillance and collision prediction for space debris. As one of space debris measuring technology based on the ground-based electro-optic telescopes, laser ranging is the most accurate. According to characteristic of laser ranging to space debris and aiming at the international technical development, through the development of high power laser system and the breakthrough of high efficiency laser signal detection, the space debris laser ranging system with the aperture of 60 cm telescope was set up as the pioneer in the development of laser measurement to space debris in China. The routine laser measurement of space debris were implemented with the measured distance from 500 km to 2 600 km, cross section from less than 0.5 m2 to more than 10 m2. According to the laser ranging link equation of space debris, combining with the statistic of laser echoes, and considering the sunlight arcs of space debris orbit when passing through the ground station, the detection simulation model of ground-based laser ranging system were constructed. The evaluation of detected ability of space debris laser ranging system with 60 cm aperture telescope was also performed with the capability of measuring debris at the distance of 1 000 km and diameter of more than 50 cm which accorded with the actual measurement results. The simulation models of laser ranging to space debris will lay the foundation for the ground-based laser ranging system with high efficient running and development of observation equipment and evaluation of detection efficiency in future.
2017, 46(3): 329002.
doi: 10.3788/IRLA201746.0329002
Impulse coupling effect of short pulsed laser ablation the target has great application in the fields of laser ablation micro-thruster and laser orbital debris removal. High precision impulse measurement is the necessary method in studying the impulse coupling effect. The torsion pendulum with laser interferometer method was put forward and the measurement system was constructed. In light of the problems of vertical axis vibration and existing error angle in the initial state of torsion pendulum, the high frequency vibration will lead to the non uniform spacing in laser interference fringes, besides, the initial angle will lead to the bright stripe advancing, these two factors will lead to the low measuring accuracy. An impulse experimental data analysis method was put forward based on ordinary least squares techniques, which can remove the high frequency noise effectively. The method can solve the problem of low measuring accuracy and improve the micro impulse method.
2017, 46(3): 329003.
doi: 10.3788/IRLA201746.0329003
The growing number of space debris threatens the flight safety of manned space station and satellites. In 2011, NASA proposed to use a continuous ground-based laser station irradiation to change orbit of space debris. The photon pressure is slight but durable, and accumulates to a considerable orbit change. The orbit change will avoid the possible collision. This method does not bring the space debris back into the atmosphere, but to prevent the collision. For the method, the spacecraft is no need to maneuver for space debris collision avoidance, and the mild photon pressure just need median power laser generator. Thus, the method gets widespread concern in recent years. However, the head-on irradiation control law in this method is simple, but not the best. It is necessary to design the optimal control law. Through the establishment of two point boundary value model to maximize the distance between two objects for control objectives, and then solving the optimality conditions, the optimal control problem is solved. The simulation shows that the modified control law has been optimized to improve the performance of collision avoidance, and the degree is very significant, concerning to the initial orbit of the space debris to avoid collision, it is usually 25% to 125%.
2017, 46(3): 329004.
doi: 10.3788/IRLA201746.0329004
Two typical materials of small scale space debris in LEO were selected. On this basis, corresponding laser ablation impulse coupling models were established respectively. The velocity variation of the space debris irradiated by high-power pulsed laser was analyzed, and the orbit transfer of the small scale space debris irradiated by laser was modeled and investigated. The variations of the orbital parameters of the space debris orbit under the irradiation of laser with assumed power were simulated and analyzed, and the influence rules of the spinning angular velocity and laser with different power on debris removal efficiency were analyzed and discussed. The simulation results show that the space-based laser of assumed power can complete the mission of removing two typical materials of debris successfully by irradiating in one cycle of flight, which provides necessary theoretical basis for the application of space debris removal by using space-based laser.
2017, 46(3): 329005.
doi: 10.3788/IRLA201746.0329005
In-orbital spacecraft has been in great danger because of centimeter space debris. Nowadays a research topic that high energy laser irradiates orbital debris to make it into the atmosphere burned down has been more and more hot. In order to take care of centimeter space debris near space station, a space-based system with high energy laser had been appeared, with a method of calculation of multiple pulses laser orbital-dropping. The simulation result shows that the possibility of removing space debris with space-based laser is that space debris is in a certain condition named cleaning window. The selection of cleaning window is the key of orbital-dropping of debris. Under the existing conditions, such as laser power and platform parameters, multiple pulse laser orbital-dropping of debris is feasible. The result of multiple pulses laser orbital-dropping shows that debris orbital parameters have a big change in eccentricity and a small change in inclination, causing a big range in perigee and a small range in apogee. After insuring range of orbital-dropping, the result of single pulse velocity increment is nearly close of multiple pulses. Because the orbital-dropping has a great difference, there cannot be calculated of orbital-dropping by a single pulse to approximate multiple pulses. Based on above discussion, the modeling and simulation of detection and removing centimeter space debris with space-based laser system can be finished.
2017, 46(3): 304001.
doi: 10.3788/IRLA201746.0304001
The skin infrared (IR) characteristics of a Unmanned Aerial Vehicle (UAV) is the most important basis for the detection and recognition of the UAV. And the aerodynamic heating of an UAVskin, the heat transfer by solar radiation and earth radiation are the key factors that are contribute to the skin IR characteristic of the UAV. The skin IR characteristics calculation model of an UAV was built based on the environment infrared radiation and that of the UAV in this work. The one-dimensional heat conduction difference equation of the UAV skin was found out by a forward-difference method. And then, based on which, the IR radiation intensity distribution of the UAV in a certain plane was calculated by importing the skin emissivity of an UAV. Finally, it is concluded that the IR radiation intensity of an UAV at 8-14 m band is far greater than that at 3-5 m band. And at the same band, the radiation intensity of the top skin is higher than that of the bottom skin.
2016, 45(S2): 30-34.
doi: 10.3788/IRLA201645.S229001
Two-Line Elements(TLE) datasets are the primary source for debris orbits. However, the orbit prediction precision for low earth orbiting space debris using the TLE-SGP4 model is far less than satisfactory. The method of orbit prediction by combining multiple TLE can achieve the purpose of improving orbit predication precision for low earth orbiting space debris. Firstly, this method determined the debris orbit using the TLE-computed positions near the TLE reference epochs as pseudo-observations in the orbit determination, and then to propagate the orbit. The method was tested by continuous TLE data on 5 debris objects at altitude of about 500-600 km during 2009. The orbit prediction results for the method and TLE-SGP4 model were compared using updated TLE data as reference orbit. The 10-day orbit prediction errors for the 5 debris are all less than 5 km using this method, which is significantly less than those from using the TLE-SGP4 model.
2016, 45(S2): 35-40.
doi: 10.3788/IRLA201645.S229002
In order to monitor the space debris effectively, on the basis of 60 cm satellite laser ranging (SLR) system, the high repetition space debris laser ranging system was established with the multiple technologies, such as the real-time modification of time offset, the closed-loop tracking of debris target, the direction control of laser beam, the real-time correction of satellite forecast and so on, which was colocation observed at space SLR system. In 26 observation days, 466 passes and 26 passes in twilight were acquired, the observed elevation from 19 to 87 degree, ranging accuracy about 1 m, range from 400 km to 1 800 km, the minimum RCS can achieve to be 0.9 m2. By comparing with results from other observatories, the high repetition frequency rate DLR system has high precision, large observation range, small RCS, and more echo data, and the observed data is stable and reliable, which has reached the international advanced level.
2016, 45(S2): 41-47.
doi: 10.3788/IRLA201645.S229003
Using the way of laser in centimeter orbital debris detection has been the hot research topic. According to space based laser detection system, a basic model of centimeter orbital debris detection was established, with selecting a particular wavelength laser, space-based platform orbital parameter and position mode of detector to reduce background noise realizing once successful detection. The relationship between the detection range, the size of debris and detection probability, the minimum detection power and the furthest distance of the system was discussed. By changing the diameter of orbital debris and laser average power, the study of effect on detection range was discussed in detail. The researches show that under the existing conditions, it can be realized that 50 km distance detection of centimeter space debris with exceeding 90%detection probability, through the filtering of environment noise and selecting of space-based platform parameter. Based on above discussion, it can provide solid basis for the future modeling and simulation research of space based laser centimeter orbital debris detection and removal.
2016, 45(S2): 48-55.
doi: 10.3788/IRLA201645.S229004
The way and characteristics of space debris detection was analyzed. Based on the discussion of the requirements of space-based optical detection system, the system's technical specifications were presented. The detection of brightness higher than sixth-magnitude stars target was achieved, the target positioning precision could reach 3.5. Through the analysis, the influence of stray light which produced of the strong light source in the field of view was controlled in the design process, and the performance of the bright and dark objects could be observed simultaneously. Technical specifications of optical system were:82 mm effective focal length; 70 mm pupil diameter; 1010 field of view; under the condition of 450-900 nm wavelength range, 2 600-9 800 K color temperature range, the deviation of energy centre is better than 3m in the field of view of 0.85, the deviation of energy centre between the various temperature color is better than 1m, meanwhile, spot diagram energy concentration is greater than 75% in the 22 pixel and the spot diagram energy concentration is not less than 90% in the 33 pixel. The requirements of dark targets observation can be met by the sun to suppress the angle is greater than 50, and the PST is not higher than 10-8 which are indicated by the simulation and analysis with the design of baffles and camera lens structures.
2016, 45(S2): 56-61.
doi: 10.3788/IRLA201645.S229005
The core of inferring the debris' tumbling rate via point brightness is to acquire the periodical information of the debris' light curves. Cross-residue method was introduced to infer tumbling rate from the light curves while experimental analysis was made to justify its performance. First, theoretical analysis of cross-residue technique was provided with comparison to other rate inferring methods. Then, experimental measurements of a high-fidelity GEO debris model's light curves under 4 tumble attitudes were conducted as well as cross-residue analysis. Finally, the concept of Cross-residue Reciprocal Peak Significance Rate was put forward to analyze the light curve's cross-residue results, and spectral significance rates were calculated to figure out the best detection waveband. Experimental data shows that tumbling period is accurate and the best detection band is 380-490 nm. The current findings present a foundation for designing of future space-based and ground-based debris surveillance system.
2016, 45(S2): 62-70.
doi: 10.3788/IRLA201645.S229006
The orbital covariance information of debris is wildly used in projects such as uncorrelated tracks catalog and spacecraft collision warning to calculate collision probability. Orbital covariance information contains initial orbit error, measurement equipment error and perturbation model error. It's very important to make a prediction for the covariance above. In the paper, covariance analysis was conducted on low earth orbital objects, International Space Station(ISS) and Japanese satellite AJISAI. The covariance prediction was made through UT transform method of Unscent Kalman Filter and linear covariance method based on Jacobian transform. The simulation results shows that for a period of 200 minutes time, through UKF method the covariance prediction accuracy of ISS increases. But for satellite AJISAI covariance predicted by UKF and linear methods are almost the same. And then, the covariance prediction result from the two methods was compared. At last, through Monte-Carlo method the accuracy of the covariance prediction was verified.
2016, 45(S2): 71-76.
doi: 10.3788/IRLA201645.S229007
According to the signal model of space debris, the frequency diversity technology was reconciled in the imaging method. The frequency diversity can suppress the angle glint of debris, and the average signal-to-noise ratio of echo will be improved. Meanwhile, the demand of bandwidth of two-dimensional imaging of high-speed space debris with small size was too wide to realize, then the low-resolution signal was used to the high-resolution imaging, the bandwidth was much smaller than the need of ISAR, and the influence of the equivalent integration angle caused by high-speed was considered, through the estimation of the equivalent rotating speed, the matched-filter was corrected, which can match the need of rotating imaging and accomplish the imaging. Finally, a simulation of trumpet debris was modeled and made by the method projected in this paper. The result indicates that the method can suppress the angle glint of debris during the time of imaging, and the high resolution image is achieved.
2016, 45(S2): 77-83.
doi: 10.3788/IRLA201645.S229008
According to the signal model of LFM radar, the reason of range, Doppler and wave beam migration, and the variety of target RCS during accumulation period in space debirs detection were analysed. Based on research of compensation on striding three dimension, flight path tracking, and frequency diversity, the signal timewidth and bandwidth influencing on radar detecting ability were analysed and simulated, and a conclusion was obtained that this method was applicable for solving target capture and tarcking precision from far to near distance. At last the simulation demonstrates the validity of the algorithm with providing the compensation on Doppler dimension, LS and Kalman in flight path tracking and variety of range for frequency diversity method.
2016, 45(S1): 169-176.
doi: 10.3788/IRLA201645.S129001
A method of detecting and recognizing space debris based on visible light camera and laser range finder was proposed in this paper. The shape of imaging was determined by the relative velocity, and distance of space debris. In order to matching different images, an ellipse that had the same second-order central moment was adopted to describe the edge of image. Based on the features of ellipse, the rules of matching images will be established. By matching different images, the coordinate and azimuth angles can be calculated. If only the azimuth angles were available, the relative position-velocity filter was used for guiding the laser range finder. When the laser range finder worked properly, the extend-Kalman filter was used for getting accurate movement information of the target.
2016, 45(S1): 177-182.
doi: 10.3788/IRLA201645.S129002
The optimizedfluid mechanics model was fabricated to solve the plasma of space debris excited by nanosecond pulse laser. Fluid mechanics model was divided into solution of plasma state equation, energy coupling between laser and space debrisand momentum coupling coefficient. In each module implements, time and space distribution of temperature, velocity, pressure and density of debris plasma were analyzed. Considering the influence of plasma shielding effect to the laser efficiency, innovation was putt forward to achieve the highest efficiency of laser to clean up space debris by the method of absorption mechanism of layer by layer. Influences of pluse width and power density to the momentum coupling coefficient were acheived. Finally, comparing the result to experimental experience data prove the verification of the simulation.
2016, 45(2): 229001.
doi: 10.3788/IRLA201645.0229001
Using the way of laser in centimeter scale space debris removal has been the hot research topic around world.The characteristics of impulse coupling and reducing the speed and de-orbit with space debris induced by laser irradiation are utilized in their removal.According to the two characteristics,four key problems,that were space debris plasma plume induced by laser ablation,measurement of space debris impulse by laser ablation,space debris orbit estimating and laser parameters in space debris removal,were discussed in detail.The concerned technology difficulties,the adopting research methods and the realized ability level were analyzed.Based on the above discussion,it can provide solid basis for its future project realization.
2016, 45(2): 229002.
doi: 10.3788/IRLA201645.0229002
The effect of expansion moving and impulse coupling in pulse laser and aluminum target debris were investigated, the spatial and temporal distribution rules of velocity and pressure in aluminum target debris and plasma were analyzed by numerical simulation, and the quantitative relation of impulse coupling coefficient and laser power densities was also discussed. Further, a dynamic deorbit model of ground-based pulse laser irradiating small scale space debris in low earth orbit(LEO) was established, and the effects of orbital eccentricity and perigee altitude with different number of pulses were simulated in the process of removing small scale space debris in LEO. The results indicate that the small scale space debris in LEO could be deorbited availably by optimal impulse coupling coefficient when the number of pulses was 180 times, orbital eccentricity was 0.071 based on the condition of this paper. The prospective achievements can provide technical guidance for the application of high power laser removing space debris in LEO.
2016, 45(2): 229003.
doi: 10.3788/IRLA201645.0229003
To contribute to the improvement of China's radar debris tracking capability and capacity, efforts have been made to make the newly built Qujing incoherent scattering radar capable of LEO debris surveillance, in addition to its standard space environment observations. Firstly, a brief introduction of the Qujing radar and its operational parameters were given, followed by the discussion of the debris tracking sensitivity. The modified radar system was operated on November 18, 2014, to experiment its debris tracking capability. The experiments show that the measured ranges agree well with external values, and this confirms the debris tracking feasibility of the Qujing radar. After the planned system upgrades, the Qujing radar is expected to track debris objects as small as 5 cm, and the tracking capability and capacity, including the natural celestial bodies, would be greatly enhanced through the networking with other radars.
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