Hauke Fiedler

Hauke Fiedler
German Aerospace Center (DLR) | DLR

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151
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Publications

Publications (151)
Chapter
The environment in which spacecraft have to function is not only life-threatening for humans but also challenging for the spacecraft itself. To successfully cope with this environment many aspects including acceleration, atmosphere, vacuum, solar radiation and its implications have to be taken into onsideration. Such factors are examined in more de...
Conference Paper
In the launch and early orbit phase of a satellite mission, reliable information on the spacecraft’s position is of vital importance for the success of the whole mission. Especially for spacecraft targeting geostationary positions, ground-based orbit information is necessary for planning and calibrating the required manoeuvres to transfer the satel...
Conference Paper
The telescope network SMARTnet, established and operated by the German Aerospace Center (DLR) in close cooperation with the Astronomical Institute of the University of Bern (AIUB), is conceptualised to collect and distribute data from telescope stations. Contributing stations owned and operated by DLR are running remotely and autonomously. When the...
Conference Paper
As space is more contested and congested, it is a prerequisite to keep space as clean as possible for long term sustainability. One mean is the disposal of spacecraft after the end of their mission. For the time between end of mission and re-entry, several suggestions have been made, and one acknowledged proposal is the 25-year guideline. This guid...
Conference Paper
Full-text available
In this paper, a modified version of the finite set statistics-based Probability Hypothesis Density (PHD) filter is developed specifically for the optical multi-target tracking of objects in the near-Earth realm for Space Situational Awareness (SAA). A two-step PHD filter is proposed in a modified version. One labeled PHD filter is used on the orth...
Conference Paper
SMARTnet is conceptualised to be a worldwide network of passive-optical telescope stations. They are operated by the German Space Operations Center (GSOC) of the German Aerospace Center (DLR), together with partners who operate their own telescope station and provide tracklets. DLR’s second telescope station is located at Mt Kent near Toowoomba in...
Conference Paper
For Space Situational Awareness, the German Aerospace Center (DLR) develops the software system "Backbone Catalogue of Relational Debris Information" (BACARDI), which allows for keeping track of resident space objects. BACARDI's key features are automated processing services which produce orbit information and products like collision warnings. We p...
Conference Paper
We present the "Backbone Catalogue of Relational Debris Information" (BACARDI) as an effort of the German Aerospace Center (DLR) to keep track of cooperative and uncooperative orbital objects. Key features of BACARDI are a database storing information about all known orbital objects, and a set of processing services that produce orbit information a...
Conference Paper
Allgemeiner Vortrag über Space Debris und SMARTnet.
Conference Paper
Operation of satellites and research of their orbital regions depend on both modelling e. g. of the environment and data banks consisting of objects with preferably high accuracy ephemerides and, if possible, completeness of the number of objects in this region. If concentrating on the geostationary regime, it is assumed that a detection size of an...
Conference Paper
Operation of geostationary satellites and research of the geostationary region depend on both modelling e. g. of the environment and data banks consisting of objects with preferably high accuracy ephemerides and, if possible, completeness of the number of objects in this region. Of course, due to physical reasons, not all objects are detectable, bu...
Conference Paper
The current situation of Space Debris, possible future scenarios, and trends which may contribute to this situation are presented.
Conference Paper
For a better understanding of the space environment and for safe and secure satellite operations, the German Space Operation Center (GSOC) together with the Astronomical Institute of the University of Bern (AIUB) have established SMARTnet™. Its main purpose is to act as an exchange platform for observational data of resident space objects. Its oper...
Conference Paper
Detecting manoeuvres of satellites in a database is an issue to keep those objects in the database instead of having multiple instances. Those multiple instances may occur because manoeuvres lead to difficulties in the object identification and orbit determination process. Efficient manoeuvre detection helps reducing the number of duplicate objects...
Conference Paper
Full-text available
This paper presents the plan and first results of a photographic survey of the outer surface of the Columbus module with emphasis on the forward facing areas. This is to perform a status check of the Columbus meteoroid and debris protection system (MDPS) and to obtain information on the space debris and meteoroid environment of the ISS (Internation...
Conference Paper
We summarize the main results from an evaluation study which we conducted on behalf of ESA with the aim to identify key pillars for a European Space Traffic Management (STM) system. Our primary focus is on suborbital space transportation, specifically on point-to-point (p2p) connections for human space travel/cargo transportation (including vertica...
Conference Paper
Operation of geostationary satellites and research of the geostationary region depend on both modelling e. g. of the environment and data banks consisting of objects with preferably high accuracy ephemerides and, if possible, completeness of the number of objects in this region. Of course, due to physical reasons, not all objects are detectable, bu...
Conference Paper
Topics: - Updates on SMARTnet - Ground Based Optical Sensors for GEO Monitoring - Creating catalogues and space objects and providing mechanisms for information sharing
Conference Paper
Situation awareness of objects in the geostationary regime is of great interest for collision avoidance by active satellites as well as for scientific research on the space debris population and their evolution over time. As the number of satellite operators and researches in this field is large, it makes sense to set up a sensor network with multi...
Article
In this paper, a scoring metric for space surveillance sensor observations is introduced. A scoring metric allows for direct comparison of data quantity and data quality, and makes transparent the effort made by different sensor operators. The concept might be applied to various sensor types like tracking and surveillance radar, active optical lase...
Conference Paper
Situation awareness of objects in the geostationary regime is of great interest for collision avoidance by active satellites as well as for scientific research on the space debris population and their evolution over time. As the number of satellite operators and researches in this field is large, it makes sense to set up a sensor network with multi...
Conference Paper
With space debris becoming more and more a concern for satellite operators, efforts need to be initiated to sustain a safe space environment and stop the permanent increase of debris. One of many is the active removal of large objects - 5 to 15 per year. The present paper introduces a concept based on a kit-chaser system: A chaser satellite will at...
Conference Paper
Full-text available
Optical tracklets collected after or during a maneuver phase cannot be directly associated to any cataloged object. The observations do not provide enough information for an independent orbit determination. Thus, the new orbit remains uncertain before collecting any additional measurements. Two methods for the correlation and orbit recovery are pre...
Article
There are high expectations for a global commercial space travel market which is expected to turn into a multi-billion Euro business in the next two decades. Several key players in the space business, companies like Virgin Galactic, SpaceX, Blue Origin or SNC are preparing to serve this market by developing their own ballistic reusable space vehicl...
Article
This is the second (Paper II) in a mini series of three papers that summarise the final results from an evaluation study which DLR GfR and its partners conducted on behalf of ESA. The objective of this study was to generate a roadmap for the implementation of a European Space Traffic Management (STM) system within the next two decades under consider...
Article
This third paper (Paper III) concludes the mini series of papers which presents results from an ESA-funded evaluation study that has been collected by DLR GfR and its partner institutes and companies. The objective of this study is to generate a roadmap for the implementation of a European STM system within the next two decades under consideration...
Conference Paper
High area-to-mass ratio objects (HAMR) are objects that are highly perturbed especially by non-conservative forces such as drag and solar radiation pressure. As a consequence, they are population different orbital regions than low area-to-mass ratio objects. This makes the objects hard to detect. After initial detection those objects are often lost...
Conference Paper
Uncooperative objects in space, in particular space debris, have become a serious challenge for active satellites. One solution to master the situation is the active removal of large debris. This again requires the technology for rendezvous & docking maneuver. While various ideas for the capture exist, simulations are required for sufficient testin...
Conference Paper
Operational satellites in the geostationary orbit region (GEO) have to perform station keeping manoeuvres to maintain their longitude and inclination. When maintaining an object catalogue, these manoeuvres lead to difficulties within the object identification process. It is possible that the catalogue contains multiple instances of the same object,...
Conference Paper
The importance of protecting the geosynchronous region from space debris requires continuous monitoring in order to support collision avoidance operations. Accurate orbit information is prerequisite to avoid manoeuvres which might shorten the mission time. To gain this information, follow-up observations are necessary to maintain the accuracy of ep...
Article
Over the last 60 years, Space Debris has become one of the main challenges for the safe operation of satellites in low Earth orbit. To address this threat, guidelines that include a limited debris release during normal operations, minimization of the potential for on-orbit break-ups and post mission disposal have begun to be implemented. However, f...
Article
Full-text available
Catalog maintenance for Space Situational Awareness (SSA) demands an accurate and computationally lean orbit propagation and orbit determination technique to cope with the ever increasing number of observed space objects. As an alternative to established numerical and analytical methods, we investigate the accuracy and computational load of the Dra...
Conference Paper
Efficient sensor tasking is a crucial step in building up and maintaining a catalog of space objects at the highest possible orbit quality. Sensor resources are limited; sensor location and setup (hardware and processing software) influence the quality of observations for initial orbit determination or orbit improvement that can be obtained. Furthe...
Conference Paper
Optical observations for space debris in the geosynchronous region have been performed for many years. During this time, observation strategies, processing techniques and cataloguing approaches were successfully developed. Nevertheless, the importance of protecting this orbit region from space debris requires continuous monitoring in order to suppo...
Conference Paper
Space debris in general has become a major problem for modern space activities. Guidelines to mitigate the threat have been recommended, better prediction models are developed and an advanced observation of objects orbiting Earth is in progress. And still – without the implementation of active debris removal (ADR), the number of debris in space wil...
Conference Paper
The study presents an analysis of accuracy of observations which are contributing to the maintenance of space object catalogue. After quantifying the uncertainties in optical and radar measurements, the second part of the study presents the error within the mean element orbit determination procedure. A batch least square orbit determination method...
Conference Paper
The threat of space debris to operational satellites is a growing concern for satellite op- erators. Large objects with high collision probability, e.g. rocket bodies and non-functional satellites on highly frequented orbits, form hereby the largest source for the debris’ increase in number. Various ideas on how to remove those objects have been pr...
Conference Paper
Full-text available
The study presents an analysis of the orbit determination process for maintenance of the space object catalogue. After quantifying the uncertainties in optical and radar measurements, the second part of the study presents the error within the mean element orbit determination procedure. A batch least square orbit determination method which makes use...
Conference Paper
There are high expectations for a globally growing market of commercial space travel which is likely to turn in the next 10 to 20 years into a multi-billion Euro business. Those growth expectations are also backed up by OneWeb’s order of about 700 small satellites which are likely to be brought into LEO via air launches and by a continuously growin...
Conference Paper
In a joint project of the DLR Institute for Simulation and Software Technology and DLR Space Operations and Astronaut Training develop methods for space surveillance. The main objective of the project is to develop an orbital database for objects in Earth orbit – called the Backbone Catalogue of Relational Debris Information (BACARDI). The research...
Conference Paper
Full-text available
Over the last 60 years, Space Debris has accumulated to one of the main challenges for the safe operation of satellites in low Earth orbit. To address this threat, guidelines that include a limited debris release during normal operations, minimization of the potential for on-orbit break-ups and post mission disposal have started to be implemented....
Article
Full-text available
The awareness of space debris as a threat for the safe operation of satellites in Earth's orbit increased rapidly over the last few years. Attempts such as improving trajectory predictions of non-functional objects in space, guidelines for safer launches nowadays, and post-mission disposal maneuver, however, will not stop the growth in debris numbe...
Conference Paper
Full-text available
Space debris has become a serious problem for the safe operations of spacecraft in low Earth orbit. Attempts such as improving trajectory predictions of non-functional objects in space, guidelines for safer launches nowadays, and an implementation of post-mission disposal however will not stop the growth in debris numbers. One solution for mitigati...
Conference Paper
To ensure safe space operations, a catalogue with good ephemeris quality is required. Maintaining such a catalogue requires an accurate and precise orbit propagator that is not computationally resource consuming. Object densities in LEO, MEO and HEO regions are very high, which comprises of ∼85% of the current catalogued objects. For the purpose, D...
Article
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...
Conference Paper
In order to guarantee save operation of satellites in the geostationary orbit, space object databases are created. Close encounters between uncontrollable and active objects must be detected and maneuvers must be planned to avoid future collisions. The geostationary orbit is typically monitored using ground-based optical telescopes. They are operat...
Conference Paper
Full-text available
Several small satellites in the class of pico- and nano-satellites will be equipped with multiple small corner cubes: OPS-SAT (ESA), S-Net and TechnoSat (8 kg resp. 15 kg; Technical University Berlin), and CubETH (ETH Zuerich). The size of these satellites is in the range from 10x10x30 cm up to about 40x40x30 cm; the planned circular orbits are in...
Conference Paper
Several small satellites in the class of pico- and nano-satellites will be equipped with multiple small corner cubes: OPS-SAT (ESA), S-Net and TechnoSat (8 kg resp. 15 kg; Technical University Berlin), and CubETH (ETH Zuerich). The size of these satellites is in the range from 10x10x30 cm up to about 40x40x30 cm; the planned circular orbits are in...
Conference Paper
Full-text available
With respect to an increasing threat of space debris for the space environment, uncontrolled objects orbiting the Earth are subject to a series of activities for stabilization on the amount of man-made debris. It is well-known that one of the mitigation means, active space debris removal, (ADR) will be inevitable to achieve this goal. Mission scena...
Conference Paper
Full-text available
Even though the infinite vastness of the universe is an accepted theory, apparently infinity ends when it comes to orbits surrounding the Earth. This was a hard lesson to learn when Iridium 33 and Cosmos 2251 collided in the low Earth orbit in February 2009. Not at least due to this event, the threat of uncontrolled objects in space is subject to a...
Conference Paper
Full-text available
To alleviate the threat of space debris, a combination of debris mitigation measures and debris environment re- mediation techniques with regard to long-term environ- ment stability is required. Hereby, active space debris removal (ADR), which is subject to this paper, addresses the latter. To evolve a concept for autonomous ADR on a representative...
Conference Paper
Full-text available
Uncontrolled space objects in the geostationary orbit domain are hazardous threats for active satellites. Catalogs need to be build up, in order to protect this precious domain. The Swiss ZimSMART telescope, located in Zimmerwald, regularly scans the geostationary ring in order to provide a homogenous coverage. This surveying technique typically yi...
Conference Paper
Debris populating the geostationary orbit is mainly observed by ground-based optical telescopes. Short measurement arcs, known as tracklets, provide line-of-sight information along with the associated rates of change. In view of their limited duration, individual tracklets cannot be used to determine a full set of orbital elements for the observed...
Conference Paper
Full-text available
Currently, the number of space debris particles is about 33,500, out of which approximately 1100 are in geosynchronous orbits, which are tracked and whose orbital data are provided from US Space surveillance network, with instances of colliding and increasing the number of space debris. To further not exacerbate this situation, it is important to t...
Chapter
TanDEM-X (TerraSAR-X add-on for Digital Elevation Measurement) is a highly innovative Earth observation mission that opens a new era in remote sensing. TanDEM-X comprises two formation flying satellites, each equipped with a synthetic aperture radar (SAR) to map the Earth?s surface with high spatial resolution. Together, the two satellites form a u...
Conference Paper
Full-text available
TanDEM-X opens a new era in space borne radar remote sensing. The first bistatic SAR mission, is formed by adding a second, almost identical spacecraft, to TerraSAR-X and flying the two satellites in a closely controlled formation with typical distances between 250 and 500 m. Primary mission objective is the generation of a consistent global digita...
Article
This paper analysesthe fuel consumption of interferometric rader missions employing small satellite formations like, e.g., Cross-track pendulum, Cartwheel, CarPe, or Trinodal Pendulum. Individual analytic expressions are provides for each of the following contributions: separation from a simultaneously injected master satellite, formation set-up, o...
Conference Paper
Full-text available
Tandem-L is a proposal for an innovative interferometric and polarimetric radar mission that enables the systematic monitoring of dynamic processes on the Earth surface. Important mission objectives are global forest height and biomass inventories, large scale measurements of millimetric displacements due to tectonic shifts, and systematic observat...
Article
Full-text available
The TanDEM-X mission, result of the partnership between the German Aerospace Center (DLR) and Astrium GmbH, opens a new era in spaceborne radar remote sensing. The first bistatic satellite synthetic aperture radar mission is formed by flying TanDEM-X and TerraSAR-X in a closely controlled helix formation. The primary mission goal is the derivation...
Article
This document provides an overview of possible TerraSAR-X2 mission scenarios and a description of their key characteristics, including data products and applications. The results will form the basis for a more detailed analysis and the formulation of the TerraSAR-X2 mission requirements.
Conference Paper
Full-text available
TanDEM-X (TerraSAR-X Add-on for Digital Elevation Measurements) is currently implemented as a national Earth observation mission by the German Aerospace (DLR) and EADS Astrium GmbH. This first bistatic satellite synthetic aperture radar (SAR) mission opens a new era in spaceborne radar remote sensing. The tandem configuration is formed by flying Ta...
Conference Paper
Full-text available
TanDEM-X (TerraSAR-X add-on for digital elevation measurements) is an innovative spaceborne radar interferometer mission that will be launched in autumn 2009. This paper gives an overview of the TanDEM-X mission concept, summarizes the basic products, illustrates the achievable performance, and provides some examples for new imaging modes and appli...
Conference Paper
Full-text available
Tandem-L is a proposal for an innovative interferometric and polarimetric radar mission that enables the systematic monitoring of dynamic processes on the Earth surface. Important mission objectives are global forest height and biomass inventories, large scale measurements of millimetric displacements due to tectonic shifts, and systematic observat...
Conference Paper
Full-text available
This paper discusses the use of small satellites for future radar remote sensing applications. After a short introduction, we give first an overview of the TanDEM-X mission to be launched in autumn 2009. Here, special emphasis is put on the demonstration of innovative synthetic aperture radar (SAR) imaging techniques. Then, novel SAR configurations...
Conference Paper
Full-text available
TanDEM-X (TerraSAR-X add-on for Digital Elevation Measurement) opens a new era in space borne radar remote sensing. A single-pass SAR-interferometer with adjustable baselines in across- and in along-track directions is formed by adding a second (TDX), almost identical spacecraft, to TerraSAR-X (TSX) and flying the two satellites in a closely contro...
Conference Paper
TanDEM-X (TerraSAR-X Add-on for Digital Elevation Measurements) is an innovative spaceborne radar interferometer mission that was approved for full implementation by the German Space Agency in spring 2006. This paper gives an overview of the TanDEM-X mission concept, the data acquisition strategy with optimized performance, and provides some exampl...
Conference Paper
Full-text available
In 2004, the total zero Doppler steering was proposed to minimize the Doppler centroid for SAR applications. It was firstly implemented in the German TerraSAR-X satellite. This satellite was launched May 2007. With the already analysed data, it is now possible to compare the predictions with the already taken data from the commissioning phase. It i...
Conference Paper
Full-text available
This paper introduces the TanDEM-X data acquisition plan that fulfils the requirements of deriving a global DEM according to the emerging HRTI-3 quality standard within three years mission time. Therefore, a joint TerraSAR-X & TanDEM-X data acquisition concept is introduced. Taking this concept into account, a TanDEM-X data acquisition timeline is...
Conference Paper
Full-text available
TanDEM-X is the first bistatic space borne SAR mission. It is formed by adding a second, almost identical spacecraft to TerraSAR-X and flying them in a closely controlled formation with typical distances between 250 m and 500 m. The primary goal of the mission is the derivation of a high-precision global Digital Elevation Model (DEM) according to H...
Conference Paper
Full-text available
TanDEM-X is an innovative mission with a TerraSAR-X add-on satellite for high-resolution single-pass SAR interferometry. The TanDEM-X mission has the primary objective of generating a consistent, global DEM with an unprecedented accuracy according to the HRTI-3 specifications (2 m height accuracy, 12 m posting). Beyond that, TanDEM-X provides a con...