Man-made objects larger than 10 centimeters in Earth orbit as of July 2009
Image showing man-made objects larger than 10 centimeters in Earth orbit as of July 2009. The number of such objects continues to grow, creating a challenge of how to coordinate operation of active satellites to avoid collisions. Research into thermospheric modelling, as advocated by Berger et al. [2020] will enable better assessment of satellite collision risks, and facilitate better planning of satellite maneuvers to avoid collisions. Credit: NASA
Source: Space Weather

As our use of satellite applications increases (and hence the number of satellites in orbit increases), there is growing recognition, around the world, of the need for space traffic management, i.e. technical and regulatory provisions that promote the safe launch, operation, and return to Earth of satellites.

Space weather is an important element of the technical provisions because of its many impacts on satellite operations. One of these impacts is to drive changes in the density of the upper atmosphere (the thermosphere), leading to significant uncertainties in forecasts of satellite atmospheric drag and, hence, in the forecast position of satellites in low Earth orbit. These uncertainties can make it difficult to assess the risk of satellite collisions in this increasingly busy region of space.

Berger et al. [2020] provide a call-to-arms for research that will improve our ability to forecast changes in the density of the thermosphere, especially during geomagnetic storms. This will allow more nuanced assessment of collision risks, enabling all concerned with future space traffic management (satellite operators, space agencies, and policymakers) to do their work with greater confidence. In particular, satellite operators will be better able to assess when they can significantly reduce collision risks by using satellite thrusters to make small orbit changes. But, as their commentary shows, this can only be done if we promote research that leads to a better characterization of (and ultimately a reduction in) the uncertainty in forecasts of thermospheric density and satellite drag.

Citation: Berger, T. E., Holzinger, M. J., Sutton, E. K., & Thayer, J. P. [2020]. Flying through uncertainty. Space Weather, 18, e2019SW002373.

—Michael A. Hapgood, Editor, Space Weather

Text © 2020. The authors. CC BY-NC-ND 3.0
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