An ablation model is used to describe the interaction of small meteoroids with the Earth’s atmosphere. In this model, the mass loss of a meteoroid is determined using the saturated vapor pressure of the assumed meteoroid substance. The meteoroid is considered in two modifications as a solid and a porous object. An automated method for estimating the parameters of meteoroids (mass, size, and density) from light curves is developed based on the model of small meteor body ablation, which has been used to estimate the parameters of the Perseid meteors with a brightness of -2m to +2m. The effect of the dependence for saturated vapor pressure and the residual on the parameters of the meteoric body is analyzed. It is shown that for the same meteor, the use of different dependences for pressure or different residuals leads to the dispersion of the meteor mass estimate of not more than 10-15% of the average value, and for the meteor size not more than 35-40%. The difference between the maximum and minimum density estimates can be up to five times. The selected dependence for the saturation vapor pressure strongly affects the shape of the light curve, the quality of its approximation, and the density estimate. The average porosity for all meteoroids is 86±5%, which is close to the values for IDP. The density of meteoroids is determined with a large error. The selected model better describes meteoroids with the degree of skewness of the light curve in the range of 0.4 - 0.5. The use of the porous body model has little effect on the mass estimate, while the density estimates increase by up to 2 times.

An ablation model is used to describe the interaction of small meteoroids with the Earth's atmosphere. In this model, the mass loss of a meteoroid is determined using the saturated vapor pressure of the assumed meteoroid substance. The meteoroid is considered in two modifications as a solid and a porous object. An automated method for estimating the parameters of meteoroids (mass, size, and density) from light curves is developed based on the model of small meteor body ablation, which has been used to estimate the parameters of the Perseid meteors with a brightness of -2m to +2m. The influence of the dependence of the structure (solid/porous) on the parameters of the meteoric body is considered. The estimates of the mass of meteoroids using different model modifications are close to each other (the deviation is no more than 25%) and they coincide with the photometric mass of the meteoroid. The average porosity for all meteoroids is 72% and 84% depending on the model, which is close to the values for IDP. The density of meteoroids is determined with a large error.

Context.Precise astrometric measurements performed on meteor images are required to derive the dynamical parameters of a mete-oroid. As a consequence, the measurements carried out in this initial step will have a strong impact on the dynamical solution of an orbiting meteoroid. These measurements relate to the position of the meteor defined by the positions of pixels along its path, as well as by their uncertainties. Therefore, the use of all available information is of great importance for the subsequent processing steps.Aims.This paper examines a new geometrical approach for computing the trajectory of a meteor from multi-station observations. The model considers a more general weighting scheme based on existing stochastic information from the measurements, including the geometry between each station and the observed meteor.Methods.We present a novel mathematical model for least squares adjustment of the linear meteor trajectories within the Gauss-Helmert model, which allows the use of stochastic information from the measured direction vectors from multiple stations. Additionally, an extended stochastic model is presented that takes into account the geometric relationship between each station and the observed meteor as a weight component for each group of observations.Results.The solution of the new approach is demonstrated on a synthetic meteor example, with observations generated from multiple stations with differing precision. The geometric configuration of the stations has been chosen in such a way that it creates the necessity to include stochastic information for the observed direction vectors for a realistic solution. The results of the newly developed approach are compared with those from established methods in the literature. Future investigations and optimisations for developing an even more improved meteor trajectory model are being addressed.

Data collection via mobile software applications is playing an increasingly important role in Citizen Science projects. When developing such applications, it is important to consider both the requirements of the scientists interested in data collection and the needs of the citizen scientists who contribute data. Citizens and participating scientists therefore ideally work together when conceptualizing, designing, and testing such applications (co-design). In this way, both sides - scientists and citizens - can contribute their expectations, desires, knowledge, and engagement at an early stage, thereby improving the utility and acceptance of the resulting applications. How such a co-design process must and can be meaningfully designed depends very much on (1) the interests, skills and background knowledge of the project participants, (2) the complexity and type of the data collection methodology to be implemented, and (3) the time, financial and legal conditions under which the software is developed. In our contribution, we address this point. We present two methodologies that enable the joint design and implementation of software applications for mobile data collection in citizen science projects. These represent quite different best practice approaches that emerged during the development of mobile applications on the topics of light pollution and meteor observation in our Citizen Science project Nachtlicht-BüHNE. We examine and compare the resulting methods with respect to their suitability for use under different conditions and thus provide future citizen science projects based on participatory developed mobile applications with decision support for the design of their co-design approach. We shed light on the two co-design methods with respect to the following criteria, among others: possible types of contributions by volunteers, requirements on expertise and knowledge of the contributors, flexibility of the method with respect to changing requirements, possibilities with respect to the design of complex data collection methods, costs incurred and time required for the implementation of the methodology.

We study the process of meteoroid interaction with the Earth's atmosphere, in particular, the effect of ablation.An ablation model is used, where mass loss of a meteoroid is determined using the saturated vapor pressure of the assumed meteoroid's substance.An automated method is suggested, where we estimate the physical parameters of a meteoroid by comparing data from observations and models of known parameters.Model constraints and features of the models are discussed.

Data contributed by citizen scientists raise increasing interest in many areas of scientific research. Increasingly, projects rely on information technology such as mobile applications (apps) to facilitate data collection activities by lay people. When developing such smartphone apps, it is essential to account for both the requirements of the scientists interested in acquiring data and the needs of the citizen scientists contributing data. Citizens and participating scientists should therefore ideally work together during the conception, design and testing of mobile applications used in a citizen science project. This will benefit both sides, as both scientists and citizens can bring in their expectations, desires, knowledge, and commitment early on, thereby making better use of the potential of citizen science. Such processes of app co-design are highly transdisciplinary, and thus pose challenges in terms of the diversity of interests, skills, and background knowledge involved. Our “Nachtlicht-BüHNE” citizen science project addresses these issues. Its major goal is the development of a co-design process enabling scientists and citizens to jointly develop citizen science projects based on smartphone apps. This includes (1) the conception and development of a mobile application for a specific scientific purpose, (2) the design, planning and organization of field campaigns using the mobile application, and (3) the evaluation of the approach. In Nachtlicht-BüHNE, the co-design approach is developed within the scope of two parallel pilot studies in the environmental and space sciences. Case study 1 deals with the problem of light pollution. Currently, little is known about how much different light source types contribute to emissions from Earth. Within the project, citizens and researchers will develop and use an app to capture information about all types of light sources visible from public streets. Case study 2 focuses on meteors. They are of great scientific interest because their pathways and traces of light can be used to derive dynamic and physical properties of comets and asteroids. Since the surveillance of the sky with cameras is usually incomplete, reports of fireball sightings are important. Within the project, citizens and scientists will create and use the first German-language app that allows reporting meteor sightings. We will share our experiences on how researchers and communities of citizen scientists with backgrounds in the geosciences, space research, the social sciences, computer science and other disciplines work together in the Nachtlicht-BüHNE project to co-design mobile applications. We highlight challenges that arose and present different strategies for co-design that evolved within the project accounting for the specific needs and interests of the communities involved.

We have characterised the Perseid meteoroid stream from data acquired in a series of observing campaigns between 2010 and 2016. The data presented in this work were obtained by the Smart Panoramic Optical Sensor Head (SPOSH), an all-sky camera system designed to image faint transient noctilucent phenomena on dark planetary hemispheres. For the data reduction, a sophisticated software package was developed that utilises the high geometric and photometric quality of images obtained by the camera system. We identify 934 meteors as Perseids, observed over a long period between late July (~124°) and mid-to-late August (~147°). The maximum meteor activity contributing to the annual shower was found at λ⊙ = 140°.08 ± 0°.07. The radiant of the shower was estimated at RA = 47°.2 and Dec = 57°.5 with a median error of 0°.6 and 0°.2, respectively. The mean population index of the shower between solar longitudes of 120°.68 and 145°.19 was r = 2.36 ± 0.05, showing strong temporal variation. A predicted outburst in shower activity for the night of August 11–12, 2016 was confirmed, with a peak observed 12.75 hr before the annual maximum at 23:30 ± 15′ UT. We measure a peak flux of 6.1 × 10−4 km−2 hr−1 for meteoroids of mass 1.6 × 10−2 g or more, appearing in the time period between 23:00 and 00:00 UT. We estimate the measured flux of the outburst meteoroids to be approximately twice as high as the annual meteoroid flux of the same mass. The population index of r = 2.19 ± 0.08, computed from the outburst Perseids in 2016, is higher than the value of r = 1.92 ± 0.06 derived from meteors observed in 2015 belonging to the annual Perseid shower which was active near the time of the outburst. A dust trail with an unusually high population index of r = 3.58 ± 0.24 was encountered in 2013 between solar longitudes 136°.261 and 137°.442. The relatively high r-value implies an encounter with a dust trail rich in low-mass particles.

On September 21, 2017, a large fireball appeared over the Netherlands and vanished over the North Sea. Scores of eyewitness reports with descriptions of the phenomenon arrived through our notification e-mail address feuerkugel@dlr.de. By studying these reports, given with varying level of details, and by comparing them with other trusted sources we may appreciate how reliable and complete the reported data are. This might be helpful for us to improve our notification system in the future. Also, reports sometimes include information not easily obtained by other observing techniques. On the other hand, the reporting system is useful to promote public awareness of Earth in the environment of space.

Meteoroids entering the Earth’s atmosphere can be observed as meteors, thereby providing useful information on their formation and hence on their parent bodies. We developed a data reduction software package for double station meteor data from the SPOSH camera, which includes event detection, image geometric and radiometric calibration, radiant and speed estimates, trajectory and orbit determination, and meteor light curve recovery. The software package is designed to fully utilise the high photometric quality of SPOSH images. This will facilitate the detection of meteor streams and studies of their trajectories. We have run simulations to assess the performance of the software by estimating the radiants, speeds, and magnitudes of synthetic meteors and comparing them with the a priori values. The estimated uncertainties in radiant location had a zero mean with a median deviation between 0.03∘ and 0.11∘ for the right ascension and 0.02∘ and 0.07∘ for the declination. The estimated uncertainties for the speeds had a median deviation between 0.40 and 0.45 km s−1. The brightness of synthetic meteors was estimated to within +0.01 m. We have applied the software package to 177 real meteors acquired by the SPOSH camera. The median propagated uncertainties in geocentric right ascension and declination were found to be of 0.64∘ and 0.29∘, while the median propagated error in geocentric speed was 1.21 km s−1.

A Draconid meteor shower outburst was observed from the boards of two scientific aircraft on 8 October 2011. In this paper we report the results of this double station experiment. The beginning and terminal heights are similar to other Draconid observations and confirm the fragile nature of the meteoroids. From the distribution function of terminal heights, a critical mass was found to be about 3.5g. A behaviour of the terminal heights changes at this point. Light curves of Draconid meteors show great variability with a maximum of the F-number distribution around 0.35, which also confirms fragility of the material. Observed radiants of the meteors are in agreement with the theoretical model. Although encounters with two different filaments were predicted, it is impossible to distinguish between them from the radiants as well as the orbital data. Despite the complications with the data processing the airborne mission shows that such double station experiment is possible and provides valuable insight into meteor structure and dynamics.

Aims. We describe a new algorithm for extracting photometric information from meteor images.Methods. The time history of a moving point source of variable brightness is explicitly deconvolved from the spatial distribution of the meteor signal on the image. The method can be applied to time-integrated meteor images if kinematic information is independently available or, alternatively, assumed. Formal uncertainty estimation and reporting is included.Results. We test the algorithm on synthetic meteor images and meteors recorded during a recent double-station meteor observing campaign in Greece. In the first case, we find that both the synthetic signal and the a priori time variation of the flux are faithfully reproduced. In the second, the fluxes obtained from the two stations agree to similar to 20%.

On 8 October 2011, the Draconid meteor shower (IAU #8 , DRA) was predicted to cause two brief outbursts of meteors, visible from locations in Europe. For the first time, a European airborne meteor observation campaign was organized, supported by ground-based observations. Two aircraft were deployed from Kiruna, Sweden, carrying six scientists, 19 cameras and eight crew members. The flight geometry was chosen such that it was possible to obtain double-station observations of many meteors. The instrument setup on the aircraft as well as on the ground is described in full detail. The main peak from 1900-dust ejecta happened at the predicted time and at the predicted rate. The second peak was observed from the earlier flight and from the ground, and was caused most likely by trails ejected in the nineteenth century. A total of 250 meteors were observed, for which light curve data were derived. The trajectory, velocity, deceleration and orbit of 35 double station meteors were measured. The magnitude distribution index was high, as a result of which there was no excess of meteors near the horizon. The light curve proved to be extremely flat on average, which was unexpected. Observations of spectra allowed us to derive the compositional information of the Draconids meteoroids and showed an early release of sodium, usually interpreted as resulting from fragile meteoroids. Lessons learned from this experience are derived for future airborne meteor shower observation campaigns.

A Draconid meteor shower outburst was observed from on board two scientific aircraft deployed above Northern Europe on 8th October 2011. The activity profile was measured using a set of photographic and video cameras. The main peak of the activity occurred around 20:15 ± 0:0.5 UT which is consistent with the model prediction as well as with the IMO network visual observations. The corrected hourly rates reached a value of almost 350. The brighter meteors peaked about 15–20 min earlier than the dimmer ones. This difference can be explained by different directions of the ejection of the meteoroids from the parent comet. One of the instruments was even able to detect meteors connected with the material ejected from the parent comet before 1900 and thus confirmed the prediction of the model, although it was based on uncertain pre-1900 cometary data. Another small peak of the activity, which was caused by material ejected during the 1926 perihelion passage of the parent comet, was detected around 21:10 UT. The mass distribution index determined using the narrow field-of-view video camera was 2.0 ± 0.1. This work shows that the observation of meteor outbursts can constrain the orbital elements, outgassing activity and existence of jets at the surface of a comet.

Some past October Draconid shower meteoroids fell apart in a spray of fragments at the end of their trajectory before slowing down, from which it was concluded that these were among the most fragile meteoroids known. In those instances, the dust could not be reliably traced to a particular return of the parent comet 21P/Giaconini-Zinner. On October 8th, 2011, Earth was predicted to transverse the 1900 A.D. dust ejecta of the comet. In 1900, the comet’s perihelion distance first moved significantly inwards to the Sun and ejection conditions could have been unusual. An airborne observing campaign was organized, with several teams contributing imaging and spectrographic cameras to study the manner in which these meteoroids released the volatile element sodium during the ablation process in the Earth’s atmosphere. IMCCE, ESA, and the SETI Institute contributed spectrographic cameras based on low-light WATEC 902H2 Ultimate, low-light LCC1, and GenII XX1332 image intensified cameras. An outburst was observed, much as predicted. Despite a lack of bright meteors, a total of 15 Draconid spectra were recorded. All show evidence of an early release of sodium. The loss of sodium was observed to coincide with the formation of a distinct wake of fragments. The observations show that 21P/Giacobini-Zinner ejected fragile meteoroids during the return in 1900. Those grains may have lost some sodium even before impacting Earth.

We will organize a meteor campaign in Greece focusing on the observation of the Perseid meteor shower. Double-station observations will be carried out from 30th of July until 3rd of August using SPOSH cameras. During this period, we anticipate rates of approximately 15 Perseids per hour. The participation of graduate students during the observations and the data reduction will strengthen the educational aspect of the campaign.