Space Debris

一篇关于空间碎片的论文分析：文章从分析空间碎片这个问题的存在以及其危害性，针对其问题我们采取一定的措施来展开分析。

Space Debris

In the future, the space will be consist of much debris and the satellites will run across it in short distances. With the development of the modern technology and deep explorations for the space, the human beings will find more aliens and seek more communications with them with the help of advanced technical skills. Besides, the future exploration is to find another planet like the earth for people to live. But the space debris will be a big obstacle for human beings’ deep exploration for the space. So the troublesome problem in front of the human beings is to remove the space debris. But on basis of the technical skills, it seems too hard to complete it.
The paper will analyze the space debris from some different scientific views with the purpose to find out some questions. Through the research, the paper will give some explanations about these questions. They are: Why is space debris a problem? Where is it a problem? How are we tracking space debris? What potential solution are being discussed to remove debris from orbit?
Firstly, some explanations about the question that why space debris is a problem. Space becomes crowed and busy since the first space vehicles was launched. Many counties and corporations launch their own space vehicles in different orbits. And most of them are still in the orbits performing their functions. However, only 6 percent of space vehicles can run well. (H. Klinkrad und N. Johnson, 2010) And this means that about 60 percent is debris. What is worse, this uncontrolled debris including the abandoned rockets, the waste satellites and so on, will be a large obstacle for the space vehicles running in the orbit. Besides, the large sum of space debris is a threat for the space exploration tasks. (D. Kessler und B.G.Cour-Palais, 1978) For instance, a spacecraft is launched into the space from the surface of the earth. While the near-earth orbit is consist of space debris. When the spacecraft enters the near-earth orbit, it will run across the space debris. The hardware in the spacecraft will be broken easily. When the situation appears, the exploration task will fail. What is worse, the broken spacecraft will be another space debris in the space which will increase the sum of the debris in vicious circle. So with the development of the space technology, the space debris is a troublesome problem that the human beings need to solve it.
After knowing the bad effect brought by space debris, the second step we need to do is to know where the space debris is. In the view of the present technology, space debris is mainly distributed in the height from 700 kilometers to 1000 kilometers away from the surface of the earth. Meanwhile, the majority of space debris is distributed in the inclination from 65 degrees to 100 degrees. (J. Liou, 2011) In the past 40 years, many efforts have been thrown into the research on the space debris. From the results, it shows that space debris is mainly distributed in the low earth orbit (LEO). And the situation becomes more serious with the space task development. According to Kessler (1991), a large sum of space debris will run across with each other and create more space debris which will make more threats in the LEO in the future. In 2009, the satellite Iridium 33 ran across the waste satellite 2251 in the height of 789 kilometers. (NASA, 2009) Siberia created the space debris model in the LEO. In his paper, he pointed out that space debris not only affected the waste satellite but also was bad for the orbit. From these results, it is easy to find that the majority of space debris is distributed in the LEO. In the world, there are many countries and famous institutes which focus on the relevant research just like ESA, CNES for French Space Agency, DLR for German Space Agency, NASA, JAXA and so on. With so many efforts on the research about space debris, a conclusion can be gotten that the problem due to space debris deserves the human beings’ research.
After talking about the distribution of space debris, the following problem which needs to be solved is the tracking of space debris. If the controlled vehicle can track the target space debris, the identification of space debris will take the first place. From the relevant research, the target space debris is unknown before doing some identification on it. No matter the mass, the scale and the velocity are unknown in advance. So an efficient way to realize the identification is needed. Two kinds of sensors are used to identify the target space debris. One is the active sensor and another is passive sensor. Among the passive sensors, vision camera has been studied for many years. (Despré, N., Kerambrun, S., et al, 2010) But with the aspect to the active sensor, it has been in practice in the spacecraft docking. What is more, scanning radar has been studied as well by ESA. (Moebius, B., P fennigbauer, M., Pereira do Carmo, J, 2010) After the relevant identification for space debris, the following step is to tracking the target space debris. The technical skill in this step is the method of navigation. The purpose of identification for space debris is to get the relative velocity, the relevant distance between the controlled vehicle and the target. The purpose of navigation is to keep the relative relationship between the target space debris and the controlled vehicle. The former identification provides the basic data for the latter navigation. If the navigation performs well, the tracking of space debris will get its ideal results.
The process of tracking space debris is to provide a possible way for removing the target space debris. Usually, the method is divided into two kinds. One is the active remove and the other is the passive remove. (Nishida, S. I., Kawamoto, S., Okawa, Y., 2009) For the passive remove, the principle is to wait for space debris enters the atmospheric layer and burns. The efficiency is low and many cases in the research implies that the passive solution is not efficient. For the active remove is efficient but facing many key problems which needs to be solved urgently. The first problem is the design of the task. (Metz, M., 2012) The task covers the identification of the number of the target space debris, the tracking vehicle design and the automatic navigation skill. The second is propulsion technology. The third is the sensors used in the navigation. The fourth is the fault auto-detection technique. The fifth is the capture equipment design. The last one is the strategy out of the orbit. All the problems included in the active remove solution decide the success of the strategy. In the picture, the net is used to capture the waste target satellite.
From the explanation about space, it is easy to find space debris has been a troublesome problem, which has been a threat to the space explanation safety. The key technological skills in the removing space debris are needed to be solved in future.
Reference
H. Klinkrad und N. Johnson. (2010). “Mass Removal from Orbit, Incentives and Potential Solutions,” in 1st European Workshop on Active Debris Removal, Paris
D. Kessler und B.G.Cour-Palais. (1978). “Collision Frequency of Artificial Satellites: The Creation of a Debris Belt,” Journal of Geophysical Research, pp. 2637-2646.
J. Liou. (2011). “An Active Debris Removal Parametric Study for LEO Environment Remediation,” Advances in Space Research, pp. 1865-1876.
Kessler, D.J. (1991). Collisional cascading: the limits of population growth in Low Earth Orbit. Advances in Space Research 11(12), 63–65.
Orbital Debris Quarterly News. NASA 13(2) (April 2009)
Krag, H., Virgili, B.B. (2012) Removal Target Selection and its environmental effet. In: Cleanspace Workshop on Active Space Debris Removal, ESOC facility, Darmstadt, Germany, September 17-18.
Despré, N., Kerambrun, S., et al. (2010) HARVD, an autonomous visioni-based system for rendzvous and docking. In: 4th International Conference on Astrodynamics Tools and Techniques, Madrid, Spain.
Moebius, B., P fennigbauer, M., Pereira do Carmo, J. (2010) Imaging lidar technology - development of a 3D lidar elegant breadboard for rendezvous and cosking, test results, and prospect to future sensor applilcation. In: International Conference on Space Optics, Rhodes, Greece.
Nishida, S. I., Kawamoto, S., Okawa, Y., Terui, F., & Kitamura, S. (2009). Space debris removal system using a small satellite. Acta Astronautica, 65(1), 95-102.
Metz, M. (2012) DLR Perspective on Sustainable Use of Space. In: Cleanspace Workshop on Active Space Debris Removal, ESOC facility, Darmstadt, Germany, September 17-18.
The first picture: (space debris)
http://www.esa.int/spaceinvideos/Videos/2013/04/The_Space_Debris_Story_2013
The second picture:
http://www.bbc.com/news/science-environment-22299403
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