An optical survey for space debris on highly eccentric and inclined MEO orbits

Optical surveys for space debris in high-altitude orbits have been conducted since more than ten years. Originally these efforts concentrated mainly on the geostationary region (GEO). Corresponding observation strategies, processing techniques and cataloguing approaches have been developed and successfully applied. The ESA GEO surveys, e.g., resulted in the detection of a significant population of small-size debris and later in the discovery of high area-to-mass ratio objects in GEO-like orbits. Comparably less experience (both, in terms of practical observation and strategy definition) is available for eccentric orbits that (at least partly) are in the MEO region, in particular for the Molniya-type orbits. Different survey and follow-up strategies for searching space debris objects in highly-eccentric MEO orbits, and to acquire orbits which are sufficiently accurate to catalog such objects and to maintain their orbits over longer time spans were developed. Simulations were performed to compare the performance of different survey and cataloguing strategies. Eventually, optical observations were conducted in the framework of an ESA study using ESA’s Space Debris Telescope (ESASDT) the 1-m Zeiss telescope located at the Optical Ground Station (OGS) at the Teide Observatory at Tenerife, Spain. Thirteen nights of surveys of Molniya-type orbits were performed between January and August 2013. Eventually 255 surveys were performed during these thirteen nights corresponding to about 47 h of observations. In total 30 uncorrelated faint objects were discov- ered. On average one uncorrelated object was found every 100 min of observations. Some of these objects show a considerable brightness variation and have a high area-to-mass ratio as determined in the orbit estimation process

Assessment of post-manoeuvre observation correlation using short-arc tracklets

Satellites maintain or establish their operational orbit by performing impulsive or continuous thrust maneuvers. When cataloging resident space objects, these rapid or slow orbital changes complicate a successful correlation. The new orbit remains uncertain and cannot be used for operations such as conjunction detection. This work outlines and assesses a method for the correlation of optical tracklets to already cataloged objects and the following orbit recovery. For that purpose, historic orbital data is analyzed to predict possible states after the maneuver using kernel density estimation. The resulting probability density function also provides a measure for the association likelihood of a new tracklet. The methods are tested with optical observations from the Zimmerwald observatory. Maneuver information and ephemerides are reported by the satellite operator and used as a reference

Psychiatric Side Effects of Deep Brain Stimulation in Parkinson's Disease

Since the 1990s deep brain stimulation (DBS) has provided an effective tool for the treatment of Parkinson's disease. About fifty thousand Parkinson patients have been treated by DBS so far. Although a relatively safe intervention, there are still some considerable side effects, psychiatric and non-psychiatric. We conducted a structured search using PubMed and included publications from 1999 to February 2011 to provide an overview of the current data concerning psychiatric side effects of DBS in Parkinson's disease. There was a tremendous variety and inconsistency concerning methods and results of the studies we included. However, it became apparent that postoperatively increased attention should be paid concerning a potentially increased suicidality and affective alterations (particularly manic states). We suggest frequent pre- and postoperative evaluations of Parkinson patients treated with DBS

Assessment of post-maneuver observation correlation using short-arc tracklets

Satellites maintain or establish their operational orbit by performing impulsive or continuous thrust maneuvers. When cataloging resident space objects, these rapid or slow orbital changes complicate a successful correlation. The new orbit remains uncertain and cannot be used for operations such as conjunction detection. This work outlines and assesses a method for the correlation of optical tracklets to already cataloged objects and the following orbit recovery. For that purpose, historic orbital data is analyzed to predict possible states after the maneuver using kernel density estimation. The resulting probability density function also provides a measure for the association likelihood of a new tracklet. The methods are tested with optical observations from the Zimmerwald observatory. Maneuver information and ephemerides are reported by the satellite operator and used as a reference

The European Fireball Network 2011 – Status of Cameras and Observation Results in Germany

The European Fireball Network (EN) has been continuously operating since 1966 (Figure 1). Beginning in 1995, observing stations in Germany have been managed and operated by the DLR Institute of Planetary Research, Berlin. The stations in Germany are of the classical type, consisting of cameras on a tripod, looking down and taking images of a paraboloidal mirror. Rotating shutters mounted in front of the camera lens provide velocity information for the fast-moving meteors. Cameras are equipped with film. Typically, one longexposure image is taken every night, covering the whole sky (Figure 1). In 2011, 14 cameras were in regular operation. 59 fireballs on 81 photographs could be recorded, representing an extraordinary “fireball yield”. The number of 78 fireball co-registrations with other central-European camera systems was extraordinary as well. Data reduction and orbit reconstruction (carried out at Ondřejov Observatory, P. Spurný and team) was possible for 6 meteors. The brightest meteor, registered on May 4, had a magnitude of -10. In the area monitored by the cameras, one fireball was recorded (Figure 1), following which, with high probability, a meteorite fall occurred. Unfortunately, due to terrain conditions within the urban area of Berlin no meteorites could be recovered

The European Fireball Network 2010 - Status und Results of Cameras in Germany

The European Fireball Network (EN) has been continuously operating since 1966 (Fig. 1). Beginning in 1995, observing stations in Germany have been operated by the DLR Institute of Planetary Research. The stations in Germany are of the classical type, consisting of cameras on a tripod, looking down and taking images of a spherical mirror. Rotating shutters mounted in front of the camera lens provide velocity information for the fast-moving meteors. Cameras are equipped with film. Typically, one long-exposure image is taken every night. In 2010, 15 cameras were in regular operation. 36 fireballs on 82 photographs could be recorded, representing average “fireball yield”. Fireball co-registrations could be made with other EN stations in 20 cases, and in 3 cases with other camera types. Data reduction and orbit reconstruction (carried out at Ondřejov Observatory, P. Spurný and team) was possible for 1 meteor. The brightest meteor that was recorded in 2010 had a magnitude of -13. Progress has been made in development of a prototype digital camera version. Quite remarkably, in the area monitored by the cameras, 2 meteorite falls were recovered mainly using eyewitness reports to guide the meteorite search. Due to weather and daylight hours, no images from the cameras could be obtained. This contribution will describe the activities and results of 2010

Stellar Calibration of the Smart Panoramic Optical Sensor Head (SPOSH)

The SPOSH camera is designed for observations of transient phenomena on the night hemisphere of Earth (or other planets) from an orbiting spacecraft. It is currently being tested during observation campaigns for meteors from ground. The camera features a highly sensitive (1024 x 1024) CCD chip, a wide (>120°) field of view, is typically operated at a high rate (2 frames / sec) and has sophisticated built-in software for event detections and reporting. To calculate celestial positions and trajectories for recorded meteors it is necessary to determine the parameters for the inner and exterior orientation of the camera. Our camera model includes three orientation angles w, f, k, the focal length, the coordinates of the principal point and a second order polynomial describing the radial distortion. The model parameters are determined by stellar calibration using images of star fields recorded during recent meteor campaigns. Star positions in the images are determined from the maxima of Gauss functions fitted to the observed pixel patterns. The use of stars with their precisely known positions taken from a star catalog warrants high calibration accuracy. In recent tests we identified approximately 5.000 stars in a single image, more than 1700 of which could be related to catalog entries. After the analysis, the residual error of star positions is on average 0.25 pixels. The calibration software is developed under IDL (Interactive Data Language) and is intended to be user-friendly for less experienced users

Association of tracklets from angular and range measurements

A method is proposed to associate series of angular observations, taken with optical sensors, and range/angle observations taken with radars. The association consists in identifying the series of observations, or tracklets, that belong to the same space object. The combination of two tracklets, with angular and range measurements, is an important and sometimes necessary step to determine the orbit of an observed object