About this Research Topic
Space activities over recent decades have led to a significant increase of man-made debris in the Earth orbit. Collisions of objects in orbit (debris with debris or with operational systems) leads to even more debris. Some regions are so crowded with debris, that many scientists share the view that we are already beyond the onset of the slow and long-term collisional cascading. The collisional cascading was predicted by Donald Kessler in 1978 and is known as “Kessler Syndrome”. To slow down or even avoid the generation of new debris, adequate debris mitigation measures need to be implemented to new missions. Such mitigation measures are summarized in ISO 24113, for example.
Already existing debris in orbit poses a hazard to satellite missions and generates additional debris in case of collision. Because of the high relative velocity, even small objects (diameter ~10 μm) cause considerable degradation, for example on a lens of an optical telescope. Accordingly, larger objects are capable of destroying satellite systems or even the whole satellite. Therefore, for any new mission a threat assessment is conducted to evaluate the threat posed by already existing debris in orbit. The corresponding assessment takes place by using environmental simulation models like ESAs MASTER (Meteoroid and Space Debris Terrestrial Environment Reference) or NASAs ORDEM (Orbital Debris Engineering Model). The models are validated by using measurement data. Information regarding large objects (>~5cm in LEO; >~ 10 cm in GEO) can be provided continuously by ground based radar and telescopes. However, there is a lack of measurement data regarding the small objects (μm up to cm). Until now, the only available measurement data regarding small objects are based on retrieved hardware from space, such as LDEF (Long Duration Exposure Facility), EURECA (European Retrievable Carrier), HST (Hubble Space Telescope), and Space Shuttle windows. Considering the orbital velocity of the objects, it is clear that the space environment is of a highly dynamic nature. However, environmental models are validated with data generated almost 30 years ago. This situation makes clear, that even if the mitigation measures formulated in ISO 24113 are implemented on each satellite, the effectiveness of those measures regarding small objects cannot be validated. This is true, since there is no feedback in the system that allows for an adequate assessment of the environmental situation.
By applying a range of sensors on a number of spacecraft in different orbits, an environmental database can be generated. This database contains information regarding the impact time, the spatial distribution of objects in space and additional characteristics such as the impact speed and object size. The measured data can be used to complement available databases such as NORAD TLE or SATCAT and close the gap where presently only very limited data exists. The data gap exists below the ground-based measurement capabilities (approx. < 1cm in LEO and < 10 cm in GEO). In sub-millimetre regime available data gained from retrieved hardware, e.g., LDEF, HST, EURECA is insufficient and outdated. Furthermore, the collected data can be used for a range of applications, such as for environmental models validation, adaptation of mitigation measures standard, and also for space-based systems optimization.
We welcome articles on the technological development, implementation, reviews, descriptions of methods and procedures of, but not limited to, the following:
• Methods and systems (e.g. satellite systems, optical cameras) for space debris and meteoroids measurement.
• Validation / improvement of simulation models using space debris and meteoroids measurement data.
• Space-based systems optimization using validated environmental simulation models.
• Required adaptation of standards once measurement data becomes continuously available.
The focus of research articles should be on contribution to improvement of the environmental situation.
Acknowledgements: Xanthi Oikonomidou, Young Graduate Trainee of European Space Agency, was involved in the preparation of this Research Topic.
Keywords: Space Debris, Meteoroids, Sensor, Database, Environmental database, space collisions
Important Note: All contributions to this Research Topic must be within the scope of the section and journal to which they are submitted, as defined in their mission statements. Frontiers reserves the right to guide an out-of-scope manuscript to a more suitable section or journal at any stage of peer review.