1. Space Environment
Lecture 24 – Space Debris (Vol. 1)
Space surveillance & situational awareness
Professor Hugh Lewis
SESA3038 Space Environment
2. Overview of lecture 24
• In this lecture we introduce the space surveillance network and look at how
data from this feeds into a variety of space situational awareness resources,
including Space-Track (the “official” source of orbital data from the SSN)
• We also look at a commercial space surveillance networks deployed by the
companies LeoLabs and ExoAnalytic Solutions
• We take a brief look at how data from these networks are being used to
provide important space situational awareness services, particularly
conjunction predictions which are vital for ongoing space safety
Space Environment – Space Debris (Vol. 1)
3. Space debris: topic overview 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. Space Surveillance Network Space Environment – Space Debris (Vol. 1)
• The US Strategic Command (USSTRATCOM) uses the SSN to track the largest objects
in the near-Earth environment
• Objects approximately 10 cm and larger in low Earth orbit
• Objects approximately 1 m and larger in geosynchronous Earth orbit
• USSTRATCOM shares the data with the global community via Space Situational
Awareness (SSA) Sharing Agreements and the www.space-track.org website
• NASA and others use additional radars, telescopes, and in-situ measurements to
characterise objects too small to be tracked by the SSN, but large enough to threaten
human spaceflight and robotic missions
• Millimetre-sized debris represent the highest penetration risk to most operational
spacecraft in LEO
6. Space Fence Space Environment – Space Debris (Vol. 1)
• Multistatic radar
• Multiple radar stations approximately along
the 33rd parallel across Continental US
– Three transmitter sites operating at 216.98
MHz
– Master transmitter at Lake Kickapoo,
Texas (768 kW radiated power
– Six receiving stations
• Originally used in conjunction with a
network of cameras that could see
basketball-sized objects at 25,000 miles
• Detected objects directly overhead up to
12,000 km
Ceased operation in 2013
7. New Space Fence Space Environment – Space Debris (Vol. 1)
• Gallium Nitride (GaN) powered S-band
ground-based radars
• Under construction at Kwajalein Atoll
in the Marshall Islands
• Selected locations and higher wave
frequency
– Will permit the detection of much
smaller microsatellites and debris
than current systems
– 10 times the number of objects
detected
– Simultaneous detection, tracking and
characterisation of objects
https://www.lockheedmartin.com/en-us/products/space-fence.html
8. Space-Track Space Environment – Space Debris (Vol. 1)
• https://www.space-track.org/auth/login
• Space situational awareness service
provided by US Space Force, 18th Space
Control Squadron
• Free to register and access the API:
• Orbital element sets (TLEs)
• Satellite Catalog
• Re-entry predictions
• Conjunction predictions
9. Celestrak Space Environment – Space Debris (Vol. 1)
• http://celestrak.com/
• Space situational awareness service
provided by T.S. Kelso
• Free to access :
• Orbit visualisation/propagation
• Orbital element sets (TLEs)
• Satellite Catalog
• Conjunction predictions (SOCRATES)
• Space weather data
• STK scenarios
10. LeoLabs Space Environment – Space Debris (Vol. 1)
• Commercial space situational
awareness services
• Phased array radars use a beam that can
be reoriented hundreds of times a
second (no mechanical slew
mechanisms required)
• Can track multiple objects
simultaneously
• Three radar sites:
– Poker Flat Incoherent Scatter Radar
(Fairbanks, Alaska)
– Midland Space Radar (Midland,
Texas)
– Kiwi Space Radar (New Zealand)
https://www.leolabs.space/
https://digitalcommons.usu.edu/cgi/viewcontent.cgi?article=4412&context=smallsat
11. LeoLabs Data Platform Space Environment – Space Debris (Vol. 1)
• Offers data and analyses:
• Radar measurements
• Objects state estimations
• Object propagations
• Conjunction screening and alerts
– 3 million conjunctions < 100 km each day
– 800,000 conjunction messages per day
– Satellites can query the API and receive
conjunction information
– E.g. Starlink
https://www.hou.usra.edu/meetings/orbitaldebris2019/orbital2019paper/pdf/6096.pdf
12. LeoLabs Space Environment – Space Debris (Vol. 1)
https://twitter.com/leolabs_space/status/1222650724347252736
https://medium.com/@leolabs_space/the-iras-ggse-4-close-approach-a99de19c1ed9
• IRAS/GGSE 4 close approach 30 January 2020
• 47 metre predicted miss distance
13. ExoAnalytic Solutions Space Environment – Space Debris (Vol. 1)
https://exoanalytic.com/
• Space domain awareness solutions
• Global telescope network
• Independent space object catalog for high altitudes
(MEO, GEO, HEO)
• 10 million measurements per month
• Position and visual magnitude measurements
• Persistent observation/monitoring:
– Orbit determination
– Pattern of life analysis
– Manoeuvre characterization
– Light curve signature analysis
14. Space Environment – Space Debris (Vol. 1)
AstriaGraph
• Dr Moriba Jah, University of Texas - Austin
• TED Fellow
https://twitter.com/moribajah
https://en.wikipedia.org/wiki/Moriba_Jah
16. Space Environment – Space Debris (Vol. 1)
AstriaGraph
• Space Domain Awareness
• http://astria.tacc.utexas.edu/AstriaGraph/
• https://github.com/ut-astria/AstriaGraph
• https://www.scientificamerican.com/article/the-quest-to-conquer-earths-space-junk-problem/
17. Recap of lecture 24
• In this lecture we introduced the space surveillance network and very
briefly looked at how data from this feeds into a variety of space situational
awareness resources:
– Space-Track (the “official” source of orbital data from the SSN)
– Celestrak
• We also looked at a commercial space surveillance network deployed by
the company LeoLabs
• We took a brief, high-level look at how data from these networks are being
used to provide important space situational awareness services,
particularly conjunction predictions which are vital for ongoing space
safety
• In the next lecture we focus on the systems being used to measure and
characterise space objects
Space Environment – Space Debris (Vol. 1)
18. Activities
• Visit the LeoLabs website:
• https://www.youtube.com/ch
annel/UCM5tRph-
FDk5ZxAeIp090gQ
• Visit the AstriaGraph website:
• http://astria.tacc.utexas.edu/
AstriaGraph/
Space Environment – Space Debris (Vol. 1)
