Carolin Frueh

Purdue University, Aeronautics and Astronautics, Faculty Member

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Associate Professor, Purdue University, School of Aeronautics and Astronautics. Ph.D., Physics with Specialization in Astronomy, University of Bern, Switzerland, 2011. MS of Science, Karlsruhe Institute of Technology, Germany 2006.

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Johannes Zachhuber

University of Oxford

Galen Strawson

The University of Texas at Austin

James Elkins

School of the Art Institute of Chicago

Gabriele Guidi

Indiana University

Vianney Lebouteiller

Cornell University

David Seamon

Kansas State University

Shaun Gallagher

University of Memphis

Patricia Scully

University of Galway

Armando Marques-Guedes

UNL - New University of Lisbon

Eros Carvalho

Universidade Federal do Rio Grande do Sul

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Books by Carolin Frueh

Identification of Space Debris

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Papers by Carolin Frueh

Initial Taxonomy and Classification Scheme for Artificial Space Objects Based on Ancestral Relation and Clustering

amos, Sep 1, 2013

Variation of Area-to-Mass-Ratio of HAMR Space Debris Objects

An unexpected space debris population has been detected in 2004 Schildknecht et al. (2003, 2004) ... more An unexpected space debris population has been detected in 2004 Schildknecht et al. (2003, 2004) with the unique properties of a very high area-to-mass ratio (HAMR) Schildknecht et al. (2005a). Ever since it has been tried to investigate the dynamical properties of those objects further. The orbits of those objects are heavily perturbed by the effect of direct radiation pressure. Unknown attitude motion complicates orbit prediction. The area-to-mass ratio of the objects seems to be not stable over time. Only sparse optical data is available for those objects in drift orbits. The current work uses optical observations of five HAMR objects, observed over several years and investigates the variation of their area-to-mass ratio and orbital parameters. A normalized orbit determination setup has been established and validated with two low and two of the high ratio objects, to ensure, that comparable orbits over longer time spans are determined even with sparse optical data.

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Satellite Shape Recovery from Light Curves with Noise

In this paper, the light curve inversion for the shape retrival is addressed. The focus of the pa... more In this paper, the light curve inversion for the shape retrival is addressed. The focus of the paper is on a methodology that can be used with real observations that are affected significantly by noise. At the same time, only a limited amount of time can be made available per object to collect measurements. The investigation in this paper consists of a twofold; for one the conditions are investigated that allow for a successful inversion. Using observability analysis observation scenarios for the efficient light curve collection with sufficient data for an inversion are shown. Secondly, a solution to the inversion itself is shown. A fist case, showing the effect of insufficient observability in the inversion is shown. Subsequently, two light curves are used, one with full inversion and one with insufficient observability. Togther they are used to overcome the effect of the measurement noise distortions. It is shown that the approach outperforms a classical inversion.

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Realistic Sensor Tasking Strategies

Efficient sensor tasking is a crucial step in building up and maintaining a catalog of space obje... more 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. Furthermore, improved sensing capabilities are expected to lead to an increase of objects that are sought to be maintained in a catalog, easily reaching over 100’000 objects. Sensor tasking methods hence need to be computationally efficient in order to be successfully applied to operational systems, and need to take realistic constraints, such as limited visibility of objects, time-varying probability of detection and the specific capabilities in software and hardware for the specific sensors into account. This paper shows a method to formulate sensor tasking as an optimization problem and introduces a new method to provide fast and computationa...

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Determining Debris Characteristics from Observability Analysis of Artificial Near-Earth Objects

Observability analysis is a method for determining whether a chosen state can be determined from ... more Observability analysis is a method for determining whether a chosen state can be determined from measurements. The state is typically composed of position and velocity; however, including object characteristics beyond position and velocity can be crucial for precise orbit propagation. For example, solar radiation pressure has a significant impact on the orbit of high area-to-mass ratio objects in geosynchronous orbit. Therefore, determining the time required for solar radiation pressure parameters to become observable is important for understanding debris objects. The focus of this work is the development and implementation of an extended state discrete time-varying observability analysis tool for debris objects. Previous results on incorporating measurement noise into observability analysis are implemented to determine the effect of measurement noise on extended state observability analysis. Ten objects, five low Earth objects and five geosynchronous objects, are simulated for seve...

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A new multi-target tracking algorithm for a large number of orbiting objects

Advances in Space Research, 2019

This paper presents the filter for Hypothesised and Independent Stochastic Populations (HISP), a ... more This paper presents the filter for Hypothesised and Independent Stochastic Populations (HISP), a multiobject joint detection/tracking algorithm derived from a recent estimation framework for stochastic populations, in the context of Space Situational Awareness. Designed for multi-object estimation problems where the data association between tracks and collected observations is moderately ambiguous, the HISP filter has a linear complexity with the number of objects and the number of observations. Because of its scalable complexity, the HISP filter is a promising solution for the construction of a large-scale catalogue of Resident Space Objects. We illustrate the HISP filter on a challenging surveillance scenario built from real data for 115 satellites of PlanetLabs' Dove constellation, and simulated observations collected from two sensors with limited coverage and measurement noise, in the presence of false positives and missed detection.

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Object Image Linking of Earth Orbiting Objects in the Presence of Cosmics

In survey series of unknown Earth orbiting objects, no a priori orbital elements are available. I... more In survey series of unknown Earth orbiting objects, no a priori orbital elements are available. In surveys of wide field telescopes possibly many nonresolved object images are present on the single frames of the series. Reliable methods have to be found to associate the object images stemming from the same object with each other, so-called linking. The presence of cosmic ray events, so-called Cosmics, complicates reliable linking of non-resolved images. The tracklets of object images allow to extract exact positions for a first orbit determination. A two step method is used and tested on observation frames of space debris surveys of the ESA Space Debris Telescope, located on Tenerife, Spain: In a first step a cosmic filter is applied in the single observation frames. Four different filter approaches are compared and tested in performance. In a second step, the detected object images are linked on observation series based on the assumption of a linear accelerated movement of the obje...

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Orbit Propagation Strategies with Angle-Only Observations

ABSTRACT Precise orbit determination and prediction plays an increasingly important role the more... more ABSTRACT Precise orbit determination and prediction plays an increasingly important role the more dense the population of resident space objects becomes. In this paper different strategies are dis-cussed how to propagate an orbit with angle-only observations. Different orbital regimes are investigated as well as the influence of the temporal spacing of observations. The focus is on objects which do not perform manoeuvres to clearly separate the effects of, probably unavail-able and/or inaccurate, manoeuvre data from modeling the natural forces. Orbit determination and propagation is performed with an enhanced version of the CelMech tool (Beutler, Meth-ods of Celestrical Mechanics, Springer 2001). The ephemerides of the propagated orbits are compared to observations of the same object, which were not used for orbit determination. These additional angle-only observations serve as a ground truth. The data is analyzed with respect to predicted and actually observed covariances. As a reference two line element data (TLEs) of the US Strategic Command (USSTRATCOM) catalogue are propagated with the SDP4 propagator and the resulting ephemerides are compared to the angle-only observations.

Color Photometry and Light Curve Observations of Space Debris

The ESA debris surveys at high altitudes revealed a significant population of small-size debris i... more The ESA debris surveys at high altitudes revealed a significant population of small-size debris in GEO and GEO-like orbits. For a sub-set of the discovered objects high area-to-mass ratios were determined. The nature and the origin of most of this debris are currently unknown. There are several ways to identify possible progenitors or parent objects. Studies of the dynamical properties of the objects are one way; another possibility is to acquire more information on the sizes, shapes and possibly the material of the debris pieces. Non-resolving observation techniques like color photometry, light curves, and spectrometry are the only ground-based optical methods applicable for objects at the given distances. Objects are searched for and discovered by performing dedicated survey campaigns with the ESA 1-meter telescope (ESASDT) in Tenerife, Canary Islands. Observations are then shared in a network of observing sites, which acquire further observations allowing to determine and maintai...

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Space Surveillance Observations at the Zimmerwald Observatory

At the Zimmerwald observatory optical observations of artificial space objects are performed with... more At the Zimmerwald observatory optical observations of artificial space objects are performed with the 1m Laser and Astrometric Telescope ZIMLAT and the 0.2m Small Robotic Telescope ZimSMART. While ZIMLAT is especially used for follow-up observations of newly detected small-size space debris objects, the main field of application of ZimSMART are survey observations. The goal of these observations is the built-up and maintenance of a catalogue of geostationary objects. Furthermore ZIMLAT is routinely used for unresolved space object identification by means of colour photometry and light curve measurements. This paper will highlight the space situational awareness capabilities of the Zimmerwald observatory from a technical point of view. Examples from the routine operations as well as from requests on short notice like the support of ESA during the XMM contingency operations will be given. 1 THE ZIMMERWALD OBSERVATORY The Zimmerwald Observatory is located 10km South of Berne (Switzerla...

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Comparison of Different Methods of Ephemeris Retrival for Correlation of Observations of Space Debris Objects

In the observation of space debris objects so called trackle ts, short series of astrometric posi... more In the observation of space debris objects so called trackle ts, short series of astrometric positions spanning an interval of a few minutes, are gained. Those are correlate d with external catalogues like DISCOS, which are given in the two line elements format, and with internal c atalogues. Since the tracklets do not allow to determine a full six parameter orbit, positions and velocit ies are correlated with ephemeris. The accuracy of the ephemerides retrieved from different catalogues diffe r tremendously, the differences are discussed. The offset between predicted and observed positions of objects is also relevant in the context of space situation awareness and collision avoidance.

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Optical Observations at the Zimmerwald Observatory

The Zimmerwald Observatory, located 10 km south of Bern, belongs to the Astronomical Institute of... more The Zimmerwald Observatory, located 10 km south of Bern, belongs to the Astronomical Institute of the University of Bern (AIUB). The main instrument is the 1 m Zimmerwald Laser and Astrometry Telescope (ZIMLAT) that is used for satellite laser ranging observations (SLR) and for optical observations of Earth-orbiting satellites, in particular of space debris in high altitude orbits. Astrometric and photometric measurements, as well as light-curves are acquired while performing optical observations. Additionally, minor planets and Near-Earth objects (NEOs) are in the observation schedule. ZIMLAT is operated every night if weather permits. With the observations acquired at Zimmerwald AIUB ensures the necessary follow-up observations of space debris objects discovered during the ESA surveys performed at the ESA Space Debris Telescope (ESASDT) on Tenerife. Beside this, the AIUB provides observations from the Zimmerwald Observatory to the Pulkovo cooperation of optical observers (PULCOO)....

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Identification of Space Debris

Method for Multi-Target Tracking Using a PHD-Filter in the Presence of Uncertain Probability of Detection

Multi-target tracking using probabilistic finite set statistic methods, such as the Probability H... more Multi-target tracking using probabilistic finite set statistic methods, such as the Probability Hypothesis Density (PHD) filter, the Cardinality Probability Hypothesis Density filter (CPHD) or Multi-Bernoulli methods, are ubiquitously used for their advantageous properties of probabilistic data association in the presence of measurements that originate from real objects as well as clutter and their ability of probabilistic scene description in the absence of measurements. However, the performance of such methods crucially depends on their input parameters, such as the probability of birth and death of objects in the scene and the probability of detection and the clutter rate. While birth and death are of subordinate relevance in the SSA problem, and clutter usually can be well assessed on the sensor level, the probability of detection is a traditionally uncertain parameter. The probability of detection depends upon object properties, such as shape, attitude, and materials. While tho...

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Combination of Light Curve Measurements and Orbit Determination for Space Debris Identification

Since the first satellite Sputnik was launched 1957, the number of space resident objects has inc... more Since the first satellite Sputnik was launched 1957, the number of space resident objects has increased constantly. The majority of those objects are so called space debris; objects with no intended use any more. The Astronomical Institute of the University of Bern (AIUB), Switzerland, has maintains a catalogue of space resident objects in geostationary and geostationary transfer orbits for over ten years now. Besides position measurements for orbit determination, also light curve measurements are performed regularly with the Zimmerwald Laser and Astrometry telescope (ZIMLAT), located at Zimmerwald, Switzerland.

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Orbital Dynamics of Lightweight Flexible Debris

An unexpected space debris population was recently identified as being very high area-to-mass rat... more An unexpected space debris population was recently identified as being very high area-to-mass ratio (HAMR) debris in geostationary orbit (GEO). Scientists hypothesised about their origins, consensus is that these objects are multi-layer insulation (MLI), separated from the spacecraft due to fragmentation events or delamination. These objects, like any other debris, pose a collision hazard for active satellites. Debris are usually considered rigid bodies; this assumption, however, is not fully justified for the MLI, as it lacks almost any structural strength. Large sheets of MLI are very flexible, and the change in geometry due to their flexibility can affect the effective area-to-mass ratio (AMR). This will cause varying effects due to external or internal forces and moments such as solar radiation pressure SRP, atmospheric drag, electromagnetic fields, or centrifugal and Coriolis forces. This, in turn, will affect the evolution of the orbital parameters, in a way that is difficult ...

Comparisons of PHD Filter and CPHD Filter for Space Object Tracking

Status Report on the ESA Optical Space Debris Survey at the OGS

Investigation of properties and characteristics of high-area-to-mass ratio objects based on examples of optical observation data of space debris objects in GEO-like orbits

The Astronomical Institute of the University of Bern first di scovered in 2004 an unexpected popu... more The Astronomical Institute of the University of Bern first di scovered in 2004 an unexpected population of high area-to-mass ratio (HAMR) objects in GEO-like orbits. Due to their unique properties, these objects pose a major challenge in maintaining an orbit over longer ti me periods. The orbits of HAMR objects at high altitudes are strongly perturbed by solar radiation pr essure. Observations suggest that the objects have are in a tumbling motion state. The Astronomical Institute o f the University of Bern (AIUB) has collected a significant set of observations of HAMR objects over the past years. Some of the objects could be followed over longer time intervals.

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Identification of Space Debris

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Initial Taxonomy and Classification Scheme for Artificial Space Objects Based on Ancestral Relation and Clustering

amos, Sep 1, 2013

Variation of Area-to-Mass-Ratio of HAMR Space Debris Objects

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Satellite Shape Recovery from Light Curves with Noise

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Realistic Sensor Tasking Strategies

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Determining Debris Characteristics from Observability Analysis of Artificial Near-Earth Objects

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A new multi-target tracking algorithm for a large number of orbiting objects

Advances in Space Research, 2019

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Object Image Linking of Earth Orbiting Objects in the Presence of Cosmics

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Orbit Propagation Strategies with Angle-Only Observations

Color Photometry and Light Curve Observations of Space Debris

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Space Surveillance Observations at the Zimmerwald Observatory

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Comparison of Different Methods of Ephemeris Retrival for Correlation of Observations of Space Debris Objects

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Optical Observations at the Zimmerwald Observatory

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Identification of Space Debris

Method for Multi-Target Tracking Using a PHD-Filter in the Presence of Uncertain Probability of Detection

Download

Combination of Light Curve Measurements and Orbit Determination for Space Debris Identification

Download

Orbital Dynamics of Lightweight Flexible Debris

Comparisons of PHD Filter and CPHD Filter for Space Object Tracking

Status Report on the ESA Optical Space Debris Survey at the OGS

Investigation of properties and characteristics of high-area-to-mass ratio objects based on examples of optical observation data of space debris objects in GEO-like orbits

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Orbit Determination with Optical Observations of HAMR Objects

Schlangenwelt

Kalliope Zeitschrift für Literatur und Kunst, 2008

Schlangenwelt Es war das Wasser, das beherrschte. Dieses grüne Wasser, durchzogen von blauen und ... more Schlangenwelt Es war das Wasser, das beherrschte. Dieses grüne Wasser, durchzogen von blauen und gelben Schlieren, dieses Wasser, das niemals stillstand. Es war immer ein leichtes Rauschen, immer ein Wogen, immer ein auf und ab der Wellenberge, immer ein Strudel dichter Gasblasen, die ihre giftigen Dämpfe an die Oberfläche entließen. Ein Umwälzen jeden Tag, das Altes immer neu nach oben spülte, bearbeitete Metallgegenstände, alte Wunden in neuen Leibern. Im Strudel des undurchsichtigen Wassers wanden sich die feisten Leiber unzähliger Schlangen, zwischen grüner Algenbündel trugen sie nachts ihre Kämpfe aus, und am Tage tauchten sie aus den Strudeln ihre gelbgezackten Rücken, blitzten mit ihre Giftzähne in die schwefelverhangenen Sonne. Nur wenigen Felsen, spitz und glitschig algenüberzogen trotzten dem Wasser, das alles Leben verschlang. Darauf drängten sich Menschen, Leib an Leib, ausgezehrt, die Haut von den Dämpfen angeätzt von der Farbe des Wassers. Mit leeren Augen blickten sie auf das Wasser, ein Schauen ohne Sehen aus dunklen Augenhöhlen, die schon alles gesehen hatte. Es war nur ein Ausdauern, ein Ausharren, ein Warten auf das nicht immer wieder kehren. Keine Stimme war zu hören, keine vergessenen Lieder, die Trost spendeten, nur das Wasser und die Blicke, die auf seiner tosenden Oberfläche ruhten. Sie ernährten sich von den Algen, dauerten an. Während der Tage galten alle Blicke dem Meer, nur in der Nacht, wenn die Sonne untergegangen und die Luft erfüllt war, von dem Tosen des Wassers und dem Aufschlagen der Schlangenleiber im Kampf, da drängten sich die Menschen aneinander. Wenn es kein Licht mehr gab, rückten sie näher, um sich zu spüren, spitze Knochen durch dünne Haut. Im Schmutz schwefliger Lust gebaren sie Kinder, die sie ohne sie zu besehen in die Fluten warfen, um ihnen das zu erlauben, was sie selbst nicht ertrugen. Die Schlangen nahmen diese Gaben der Menschen feist an und zerrissen die jungen Leiber im gegenseitigen Kampf. Die Mütter wandten den Blick von den Fluten ab, wagten nicht hinzusehen, und ihre Augen sanken

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Das geschenkte Universum, Astrophysik und Schöpfung, Arnold Benz, Patmos 2010, 174 S., ISBN 978-3-491-72544-7

Internationale Kirchliche Zeitung IKZ 102 (2012), Heft 1/2, 2012

Göttliche Weltökonomie, Perspektiven der Wissenschaftlichen Revolution vom 15. bis zum 17. Jahrhundert (Divine World Economy: Perspectives of the Scientific Revolution from the 15th to the 17th Century) by Dieter Groh

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