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Papers by Peter Voersmann

Aircraft Engineering and Aerospace Technology, 2007

In July 2008, an orbital debris generating incident occurred, which probably can be categorized a... more In July 2008, an orbital debris generating incident occurred, which probably can be categorized as coolant release event. The event was caused by the satellite Cosmos 1818, which contains a nuclear power system (NPS). The NPS is a reactor of the type TOPAZ, which has been inoperative since 1987. The satellite is currently on a sufficiently high orbit (SHO), where it will remain for several centuries in order to allow a decay of the radioactivity down to an acceptable level. According to American observations, the satellite has released a number of small objects. Due to the low additional velocity of these objects, this release is a low-energy event. It is assumed that the objects are sodium-potassium (NaK) droplets from the reactor's cooling system. If the debris objects are actually NaK droplets, then this is the first documented event that cannot be assigned to a Buk reactor. Some of the Buk reactors, which were used onboard satellites of the type RORSAT, have operationally ejected their reactor core and thereby opened the primary coolant loop. As a result, 16 probable 16 events occurred by the end of the 1980s, where NaK droplets have been released. These droplets contribute about 30 percent to the space debris population in 900 km altitude in the centimeter size range today. In contrast with that, the TOPAZ reactors were not designed for such an operational procedure, according to the current knowledge. Therefore, a coolant release was not expected for a TOPAZ reactor. In this work, the contribution of the possible NaK release event, caused by the TOPAZ reactor, to the existing population of orbital liquid metal droplets is investigated. A model for the description of the release will be developed, including the estimation of important parameters. These parameters are the released liquid metal mass, size distribution and number of droplets, the release velocity, and the release direction. The release event is simulated. The results of orbit propagation simulation runs are presented in terms of spatial density. The distribution of the droplets on orbits is evaluated. Furthermore, the contribution of the NaK droplets to the entire space debris population is determined.

In the year 1957 the first artificial object made by mankind was placed into an Earth orbit. This... more In the year 1957 the first artificial object made by mankind was placed into an Earth orbit. This was the beginning of space flight and also of space surveillance. During the 53 years up to now the leading nations of space flight -the United States of America and Russia (former Soviet Union) -established their own surveillance networks to be aware of the objects in space. However, the access to the resulting data was or still is restricted so that Europe intends to build up its own surveillance network in the next couple of years. Different sensor systems shall be part of the European Space Surveillance System (ESSS). Radar systems will be used for the detection of objects in low earth orbits (LEO) while traditional optical systems will be used to cover the population in the upper medium earth orbit (MEO) and the geostationary earth orbit (GEO). Modern optical satellite surveillance systems shall also be able to detect objects in the upper LEO region up to GEO. To evaluate the best setup for a future ESSS possible sensor systems have to be combined in different configurations and their performance has to be analysed. For this purpose the PROOF-2009 software will be utilized. As a base population the MASTER-2009 population for the epoch May 1st , 2040 will be used. This population includes nearly one million objects larger than one centimeter in all orbital regions from LEO to GEO and is used in upcoming studies as reference population. The comparison will be split into three parts. In the first part different radar setups will be compared while the second part deals with the comparison of different setups for optical systems to cover the population of high altitudes. The configurations for optical systems will consist of ground based or space based telescopes. Results of an analysis of the modern optical satellite surveillance systems will be shown in the third part and compared with the results of part one and two. Finally an example for an ESSS configuration allowing regular object detection will be outlined.

Parallelism is becoming the leading paradigm in today's computer architectures. In order to take ... more Parallelism is becoming the leading paradigm in today's computer architectures. In order to take full advantage of this development, new algorithms have to be specifically designed for parallel execution while many old ones have to be upgraded accordingly. One field in which parallel computing has been firmly established for many years is computer graphics. Calculating and displaying three-dimensional computer generated imagery in real time requires complex numerical operations to be performed at high speed on a large number of objects. Since most of these objects can be processed independently, parallel computing is applicable in this field. Modern graphics processing units (GPUs) have become capable of performing millions of matrix and vector operations per second on multiple objects simultaneously. As a side project, a software tool is currently being developed at the Institute of Aerospace Systems that provides an animated, three-dimensional visualization of both actual and simulated space debris objects. Due to the nature of these objects it is possible to process them individually and independently from each other. Therefore, an analytical orbit propagation algorithm has been implemented to run on a GPU. By taking advantage of all its processing power a huge performance increase, compared to its CPU-based counterpart, could be achieved. For several years efforts have been made to harness this computing power for applications other than computer graphics. Software tools for the simulation of space debris are among those that could profit from embracing parallelism. With recently emerged software development tools such as OpenCL it is possible to transfer the new algorithms used in the visualization outside the field of computer graphics and implement them, for example, into the space debris simulation environment. This way they can make use of parallel hardware such as GPUs and Multi-Core-CPUs for faster computation. In this paper the visualization software will be introduced, including a comparison between the serial and the parallel method of orbit propagation. Ways of how to use the benefits of the latter method for space debris simulation will be discussed. An introduction of OpenCL will be given as well as an exemplary algorithm from the field of space debris simulation.

Aircraft Engineering and Aerospace Technology, 2007

In July 2008, an orbital debris generating incident occurred, which probably can be categorized a... more In July 2008, an orbital debris generating incident occurred, which probably can be categorized as coolant release event. The event was caused by the satellite Cosmos 1818, which contains a nuclear power system (NPS). The NPS is a reactor of the type TOPAZ, which has been inoperative since 1987. The satellite is currently on a sufficiently high orbit (SHO), where it will remain for several centuries in order to allow a decay of the radioactivity down to an acceptable level. According to American observations, the satellite has released a number of small objects. Due to the low additional velocity of these objects, this release is a low-energy event. It is assumed that the objects are sodium-potassium (NaK) droplets from the reactor's cooling system. If the debris objects are actually NaK droplets, then this is the first documented event that cannot be assigned to a Buk reactor. Some of the Buk reactors, which were used onboard satellites of the type RORSAT, have operationally ejected their reactor core and thereby opened the primary coolant loop. As a result, 16 probable 16 events occurred by the end of the 1980s, where NaK droplets have been released. These droplets contribute about 30 percent to the space debris population in 900 km altitude in the centimeter size range today. In contrast with that, the TOPAZ reactors were not designed for such an operational procedure, according to the current knowledge. Therefore, a coolant release was not expected for a TOPAZ reactor. In this work, the contribution of the possible NaK release event, caused by the TOPAZ reactor, to the existing population of orbital liquid metal droplets is investigated. A model for the description of the release will be developed, including the estimation of important parameters. These parameters are the released liquid metal mass, size distribution and number of droplets, the release velocity, and the release direction. The release event is simulated. The results of orbit propagation simulation runs are presented in terms of spatial density. The distribution of the droplets on orbits is evaluated. Furthermore, the contribution of the NaK droplets to the entire space debris population is determined.

In the year 1957 the first artificial object made by mankind was placed into an Earth orbit. This... more In the year 1957 the first artificial object made by mankind was placed into an Earth orbit. This was the beginning of space flight and also of space surveillance. During the 53 years up to now the leading nations of space flight -the United States of America and Russia (former Soviet Union) -established their own surveillance networks to be aware of the objects in space. However, the access to the resulting data was or still is restricted so that Europe intends to build up its own surveillance network in the next couple of years. Different sensor systems shall be part of the European Space Surveillance System (ESSS). Radar systems will be used for the detection of objects in low earth orbits (LEO) while traditional optical systems will be used to cover the population in the upper medium earth orbit (MEO) and the geostationary earth orbit (GEO). Modern optical satellite surveillance systems shall also be able to detect objects in the upper LEO region up to GEO. To evaluate the best setup for a future ESSS possible sensor systems have to be combined in different configurations and their performance has to be analysed. For this purpose the PROOF-2009 software will be utilized. As a base population the MASTER-2009 population for the epoch May 1st , 2040 will be used. This population includes nearly one million objects larger than one centimeter in all orbital regions from LEO to GEO and is used in upcoming studies as reference population. The comparison will be split into three parts. In the first part different radar setups will be compared while the second part deals with the comparison of different setups for optical systems to cover the population of high altitudes. The configurations for optical systems will consist of ground based or space based telescopes. Results of an analysis of the modern optical satellite surveillance systems will be shown in the third part and compared with the results of part one and two. Finally an example for an ESSS configuration allowing regular object detection will be outlined.

Parallelism is becoming the leading paradigm in today's computer architectures. In order to take ... more Parallelism is becoming the leading paradigm in today's computer architectures. In order to take full advantage of this development, new algorithms have to be specifically designed for parallel execution while many old ones have to be upgraded accordingly. One field in which parallel computing has been firmly established for many years is computer graphics. Calculating and displaying three-dimensional computer generated imagery in real time requires complex numerical operations to be performed at high speed on a large number of objects. Since most of these objects can be processed independently, parallel computing is applicable in this field. Modern graphics processing units (GPUs) have become capable of performing millions of matrix and vector operations per second on multiple objects simultaneously. As a side project, a software tool is currently being developed at the Institute of Aerospace Systems that provides an animated, three-dimensional visualization of both actual and simulated space debris objects. Due to the nature of these objects it is possible to process them individually and independently from each other. Therefore, an analytical orbit propagation algorithm has been implemented to run on a GPU. By taking advantage of all its processing power a huge performance increase, compared to its CPU-based counterpart, could be achieved. For several years efforts have been made to harness this computing power for applications other than computer graphics. Software tools for the simulation of space debris are among those that could profit from embracing parallelism. With recently emerged software development tools such as OpenCL it is possible to transfer the new algorithms used in the visualization outside the field of computer graphics and implement them, for example, into the space debris simulation environment. This way they can make use of parallel hardware such as GPUs and Multi-Core-CPUs for faster computation. In this paper the visualization software will be introduced, including a comparison between the serial and the parallel method of orbit propagation. Ways of how to use the benefits of the latter method for space debris simulation will be discussed. An introduction of OpenCL will be given as well as an exemplary algorithm from the field of space debris simulation.