1. National Aeronautics and Space Administration “International Space Station facts and figures” (2020); www.nasa.gov/feature/facts-and-figures.
2. ESA “The current state of space debris” (2020); www.esa.int/Safety_Security/Space_Debris/The_current_state_of_space_debris.
3. ESA “Space Debris by the numbers” (2020); www.esa.int/Safety_Security/Space_Debris/Space_debris_by_the_numbers.
4. R. Khatchadourian “The elusive peril of space junk ” The New Yorker (2020).
5. “The Artemis Accords: Principles for cooperation in the civil exploration and use of the Moon Mars Comets and Asteroids for peaceful purposes” (2020) pp. 6–7; www.nasa.gov/specials/artemis-accords/img/Artemis-Accords-signed-13Oct2020.pdf.