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1. Space Environment
Lecture 20 – Space Debris (Vol. 1)
Environment status (part 1)
Professor Hugh Lewis
SESA3038 Space Environment

2. Overview of lectures 20 to 23
• In these four lectures we introduce the space debris topics we will be
looking at over the next few weeks, before focusing on the current state of
the environment, in terms of the orbital population:
– We use data and graphics from NASA, ESA and other sources to
understand the current situation and the history that has led to it
– We consider the number of objects in orbit, their mass and their
distribution (for the latter, concentrating on LEO only)
– We look at the history of space launches and fragmentations, before
seeing what the environment now looks like
Space Environment – Space Debris (Vol. 1)

3. Space debris Space Environment – Space Debris (Vol. 1)
• The space debris environment: update
• Space surveillance/measurement of space debris
• Impacts on space operations
• Modelling of space debris
• Environment/evolutionary modelling
• Impact modelling
• Breakup modelling
• Re-entry modelling
• On-ground risk modelling
• Clean Space
Volume 1 (Week 5)

4. Growth of the orbital population Space Environment – Space Debris (Vol. 1)
Data from NASA Orbital Debris Quarterly Newsletter (April 2020)
https://orbitaldebris.jsc.nasa.gov/quarterly-news/

5. Growth of the orbital population Space Environment – Space Debris (Vol. 1)
Data from Celestrak BOXSCORE (February 2021)
https://celestrak.com/satcat/boxscore.php

6. Growth of the orbital population Space Environment – Space Debris (Vol. 1)
Data from ESA’s Annual Space Environment Report (September 2020)

7. Space debris population Space Environment – Space Debris (Vol. 1)
7
Softball size or larger
(≥ 10 cm)
~34,000 ~900,000 ~128,000,000
Total mass: ~9,200 tonnes
Marble size or larger
(1 cm to 10 cm)
Ball-point pen tip
(1 mm to 1 cm)

8. Size distribution Space Environment – Space Debris (Vol. 1)
Graphic from “Orbital Debris: A Technical Assessment” (1995)

9. Growth of cross-sectional area Space Environment – Space Debris (Vol. 1)
Data from ESA’s Annual Space Environment Report (September 2020)

10. Growth of mass in orbit Space Environment – Space Debris (Vol. 1)
Data from ESA’s Annual Space Environment Report (September 2020)

11. Mass in context
Forth Road Bridge: 39,000 tonnes of steel
Space Environment – Space Debris (Vol. 1)

12. Space Environment – Space Debris (Vol. 1)
Mass in context
The Shard: 12,500 tonnes

13. Activities:
• Look back at SESA3041/6079:
• Outer Space Treaty
• Introduction to space debris
• Introduction to space debris
mitigation guidelines and standards
• IADC space debris mitigation
guidelines
• ESA’s Annual Space
Environment Report:
• Read the report (available in the
“Course Content” folder on
Blackboard)
Space Environment – Space Debris (Vol. 1)