Predicted and observed directional dependence of meteoroid/debris impacts on LDEF thermal blankets

The number of impacts from meteoroids and space debris particles to the various LDEF rows is calculated using ESABASE/DEBRIS, a 3-D numerical analysis tool. It is based on recent reference environment flux models and includes geometrical and directional effects. A comparison of model predictions and actual observations is made for penetrations of the thermal blankets which covered the UHCR experiment. The thermal blankets were located on all LDEF rows, except 3, 9, and 12. Because of their uniform composition and thickness, these blankets allow a direct analysis of the directional dependence of impacts and provide a test case for the latest meteoroid and debris flux models

EURECA 11 months in orbit: Initial post flight investigation results

This paper gives a brief overview of the European free flying spacecraft 'EURECA' and the initial post flight investigations following its retrieval in June 1993. EURECA was in low earth orbit for 11 months commencing in August 1992, and is the first spacecraft to be retrieved and returned to Earth since the recovery of LDEF. The primary mission objective of EURECA was the investigation of materials and fluids in a very low micro-gravity environment. In addition other experiments were conducted in space science, technology and space environment disciplines. The European Space Agency (ESA) has taken the initiative in conducting a detailed post-flight investigation to ensure the full exploitation of this unique opportunity

Robotic observation pipeline for small bodies in the solar system based on open-source software and commercially available telescope hardware

The observation of small bodies in the Space Environment is an ongoing important task in astronomy. While nowadays new objects are mostly detected in larger sky surveys, several follow-up observations are usually needed for each object to improve the accuracy of orbit determination. In particular objects orbiting close to Earth, so called Near-Earth Objects (NEOs) are of special concern as a small but not negligible fraction of them can have a non-zero impact probability with Earth. Additionally, the observation of manmade space debris and tracking of satellites falls in the same class measurements. Telescopes for these follow-up observations are mainly in a aperture class between 1 m down to approximately 25 cm. These telescopes are often hosted by amateur observatories or dedicated companies like 6ROADS specialized on this type of observation. With upcoming new NEO search campaigns by very wide field of view telescopes, like the Vera C. Rubin Observatory, NASA’s NEO surveyor space mission and ESA’s Flyeye telescopes, the number of NEO discoveries will increase dramatically. This will require an increasing number of useful telescopes for follow-up observations at different geographical locations. While well-equipped amateur astronomers often host instruments which might be capable of creating useful measurements, both observation planning and scheduling, and also analysis are still a major challenge for many observers. In this work we present a fully robotic planning, scheduling and observation pipeline that extends the widely used open-source cross-platform software KStars/Ekos for Instrument Neutral Distributed Interface (INDI) devices. The method consists of algorithms which automatically select NEO candidates with priority according to ESA’s Near-Earth Object Coordination Centre (NEOCC). It then analyses detectable objects (based on limiting magnitudes, geographical position, and time) with preliminary ephemeris from the Minor Planet Center (MPC). Optimal observing slots during the night are calculated and scheduled. Immediately before the measurement the accurate position of the minor body is recalculated and finally the images are taken. Besides the detailed description of all components, we will show a complete robotic hard- and software solution based on our methods.TS-R acknowledges funding from the NEO-MAPP project (H2020-EU-2-1-6/870377). This work was (partially) funded by the Spanish MICIN/AEI/10.13039/501100011033 and by “ERDF A way of making Europe” by the “European Union” through grant RTI2018-095076-B-C21, and the Institute of Cosmos Sciences University of Barcelona (ICCUB, Unidad de Excelencia “María de Maeztu”) through grant CEX2019-000918-M

The observing campaign on the deep-space debris WT1190F as a test case for short-warning NEO impacts

On 2015 November 13, the small artificial object designated WT1190F entered the Earth atmosphere above the Indian Ocean offshore Sri Lanka after being discovered as a possible new asteroid only a few weeks earlier. At ESA's SSA-NEO Coordination Centre we took advantage of this opportunity to organize a ground-based observational campaign, using WT1190F as a test case for a possible similar future event involving a natural asteroidal body. <P /

Impact studies of the HST solar arrays retrieved in March 2002

First results are presented of impact studies performed for the HST solar arrays retrieved in March 2002. The arrays have a total exposed area of 120 m2 of which 40 m2 are covered by solar cells. They had been 8.24 years in orbit at an altitude around 600 km. Most outer surfaces were surveyed for craters and holes resulting from hypervelocity impacts of meteoroids and orbiting debris. A total of 174 clear perforations of the 700 μm thick arrays were found. Measurements of impact features on the front side of the solar cells for the size range 100 μm-6 mm are reported. Different resolutions, measurement techniques and sampled areas were used to obtain statistically relevant fluxes. Measured fluxes for craters larger than 1 mm are in the order of 1.5 x 10-7 m-2 s-1. A comparison with crater measurements on the first HST solar array retrieved in 1993 shows good agreement of the fluxes. Measurements of impact features smaller than 100 μm, a chemical analysis of impact residues and a more detailed analysis of the impact data are ongoing or planned

HVI-TEST SETUP OF IN-SITU SPACE DEBRIS DETECTOR

Collisions of spacecraft in orbit with Space Debris (SD) or Micro-Meteoroids (MM) lead to payload degradation, anomalies or failures in spacecraft operation or even to loss of a whole mission. Existing flux models and impact risk assessment tools, like MASTER or ORDEM, PIRAT, ESABASE2 and BUMPER II are used to analyze the mission risk concerning this hazard potential. The validation of the flux models so far is partly based on SD and MM impact data from in-situ impact detectors, e.g. DEBIE, GORID, capture cells and on the analyses of retrieved hardware from space, e.g. LDEF, HST or EURECA. However the knowledge on the small objects populations (millimeter down to micron sized) in space is rather limited and needs to be enhanced for reliable models. As a contribution Deto soft-ware validation in terms of data acquisition, a new type of impact detector is currently under development at DLR. The Solar Generator based Space Debris Impact Detector (SOLID) makes use of spacecraft solar panels and there-fore offers a large sensor area and high flexibility regarding the orbit. This paper presents the impact detector design as well as the Hyper-Velocity-Impact (HVI) test setup, foreseen for corresponding tests at the Fraunhofer Institute for High-Speed-Dynamics, Ernst-Mach-Institut (EMI) in Freiburg, Germany

DEBRIS DETECTOR VERIFICATION BY HVI-TESTS

Information regarding Space Debris (SD) or Micrometeoroids (MM) impacting on spacecraft (S/C) or payloads (P/L) can be obtained by using environmental models e.g. MASTER (ESA) or ORDEM (NASA). The validation of such models is performed by comparison of simulated results with measured or orbital observed data. The latter is utilised for large particles and can be obtained from ground based or space based radars or telescopes. Data regarding very small but abundant particles can also be gained by analysis of retrieved hardware (e.g. Hubble Space Telescope, Space Shuttle Windows), which are brought from orbit back to Earth. Furthermore, in-situ impact detectors are an essential source for information on small size meteoroids and space debris. These kind of detectors are placed in orbit and collect impact data regarding SD and MM, sending data near real time via telemetry. Compared to the impact data which is gained by analysis of retrieved surfaces, the detected data comprise additional information regarding exact impact time and, depending on the type of detector, on the orbit and particles composition. Nevertheless, existing detectors have limitations. Since the detection area is small, statistically meaningful number of impacts are obtained for very small particles only. Measurements of particles in the size range of hundreds of microns to mm which are potentially damaging to S/C require larger sensor areas. To make use of the advantages of in-situ impact detectors and to increase the amount of impact data an innovative impact detector concept is currently under development at DLR in Bremen. Different to all previous impact detectors the Solar Generator based Impact Detector (SOLID) is not an add-on component on the S/C. SOLID makes use of existing subsystems of the S/C and adopts them for impact detection purposes. Since the number of impacts on a target in space depends linearly on the exposed area, the S/C solar panels offer a unique opportunity to use them for impact detection. Considering that the SOLID method could be applied to several S/Cs in different orbits, the spatial coverage in space concerning SD and MM can be significantly increased. In this way the method allows to generate large amount of impact data, which can be used for environmental model validation. This paper focuses on the verification of the SOLID method by Hypervelocity Impact (HVI) tests performed at Fraunhofer EMI. The test set-up as well as achieved results are presented and discussed