1. You Are Not Alone: The Problem of Safe Operations in LEO
Ted Muelhaupt
8 June 2016

2. The Problem Low Earth orbit is becoming more and more crowded
Many new large constellations proposed
Increased commercial launch rates
Space tourism is on the horizon
Existing operators are seeing an increase in collision alerts
Space debris concerns interwoven with other traffic issues
Military wants to divest itself of space traffic management and concentrate on the “protect and defend” mission
Many asking “who will be the FAA for space?”
New regulations and restrictions are likely.
What form SHOULD they take?
Some possible new constellations
Operator
Num sats
Alt (km)
Incl (deg)
LeoSat
140
1800 90
Spire
100
651
97.9
OneWeb
648
1200
SpaceX
4000
1100
Skybox 28
576
97.8
Globalstar 40
1400 52
Iridium 72
780
86.4
Orbcomm 31
750 45

3. Consider a map of LEO space – just altitude

4. New constellations will intersect with existing residents
Suborbital Flight
LeoSat +140
OneWeb +648
SpaceX +4000
Skybox +28
Iridium +72
Orbcomm +31
New constellations
Spire +100
Globalstar +40
Hubble
NASA Science – A Train
Human flight
ISS
NOAA weather
Iridium
Orbcomm
Globalstar
Existing residents

5. New constellations will intersect with existing residents
LeoSat +140
Globalstar +40
Globalstar
OneWeb +648
SpaceX +4000
NOAA weather
Iridium +72
Iridium
Orbcomm +31
Orbcomm
NASA Science – A Train
Spire +100
Skybox +28
Hubble
Human flight
ISS
Suborbital Flight

6. Space debris is where the spacecraft live
Hubble
NASA Science – A Train
ISS
NOAA weather
Iridium
Orbcomm
LeoSat +140
OneWeb +648
SpaceX +4000
Skybox +28
Globalstar +40
Iridium +72
Orbcomm +31
New constellations
Existing residents
Spire +100
Globalstar
Human flight
Suborbital Flight

7. Mass is more concentrated, different from numbers
Hubble
NASA Science – A Train
ISS
NOAA weather
Iridium
Orbcomm
LeoSat +140
OneWeb +648
SpaceX +4000
Skybox +28
Globalstar +40
Iridium +72
Orbcomm +31
New constellations
Existing residents
Spire +100
Globalstar
Human flight
Suborbital Flight

8. New constellations can locally greatly exceed existing
Hubble
NASA Science – A Train
ISS
NOAA weather
Iridium
Orbcomm
LeoSat +140
OneWeb +648
SpaceX +4000
Skybox +28
Globalstar +40
Iridium +72
Orbcomm +31
New constellations
Existing residents
Spire +100
Globalstar
Human flight
Suborbital Flight

9. New constellations can locally greatly exceed existing
Hubble
NASA Science – A Train
ISS
NOAA weather
Iridium
Orbcomm
LeoSat +140
OneWeb +648
SpaceX +4000
Skybox +28
Globalstar +40
Iridium +72
Orbcomm +31
New constellations
Existing residents
Spire +100
Globalstar
Human flight
Suborbital Flight

10. Human Space Missions are Clustered
Small group of inclinations, limits on altitude
A zone of km would encompass most human spaceflight

11. Number of Satellites in Bin
Current Catalog
Add inclination
100
101
102
103
104
Number of Satellites in Bin

12. Number of Satellites in Bin
Current Catalog
Spacecraft at same altitude but different inclinations can still intersect – depends on the right ascension
100
101
102
103
104
Number of Satellites in Bin

13. Future Catalog with New Space Constellations
OneWeb
SpaceX
+Spire
+Skybox
100
101
102
103
104
Number of Satellites in Bin

14. Future Catalog with New Space Constellations
OneWeb
SpaceX
+Spire
+Skybox
ISS
Manned missions
100
101
102
103
104
Number of Satellites in Bin

15. Disposal plans greatly affects the impact on new and old
New operational constellations are proposed for relatively unpopulated areas. But…
Constellations transiting up and down for replenishment and disposal cross other orbits
Orbits at same altitude can cross any other orbit at that altitude
A five-year lifetime implies that 20% of a constellation is replaced ~ each year
Disposal plans will directly affect conjunction frequency
OneWeb
SpaceX
+Spire
+Skybox
ISS
100
101
102
103
104
Number of Satellites in Bin

16. Large constellations will pose conjunction challenges
New constellations can double the spatial density of objects over existing levels
Collision alerts with existing operators could greatly increase
Spatial density of new constellations at ISS altitude
Note log scale

17. Large constellations pose challenges
Disposal plans will make a large difference on the traffic at non-constellation altitudes
Plot assumes a new large constellation is “spiraling down” old satellites
Spatial density of new constellations compared to existing objects
High density due to disposal

18. Even self-conjunctions are problematic for a Space Traffic Management agency
Graphic shows a 4080 satellite Walker constellation at 90 deg
One satellite passes through either pole every 1.6 sec
White rings are 20 km bubbles around each object
At any given moment, dozens of vehicles are within each others’ 20 km circle
This (naïve) example has an average of ~27, km self-conjunctions each day

19. Aspects of Space Traffic Management Problem
Space Traffic Management (STM) is multi-faceted: many things to consider
Safety concerns
On-orbit conjunction warning
Transit of airspace en route to orbit or during disposal
Space debris - environment preservation
International obligations
Space surveillance
Legislative (authority for regulations)
Legal (liability, ownership)
Regulatory business planning
US leadership
Operator code(s) of conduct
This area will evolve, perhaps quickly in some aspects.

20. Conjunction Predictions
Some questions to consider
Operators say timely and quality conjunction predictions (covariance) is of primary importance
Probability of collision has a maximum related to the covariance
Poor quality data may be un-actionable
What is the role of owner/operator data? How can/will it be ingested?
Should spacecraft file “flight plans” for maneuvers?
Post-maneuver updates?
How should we use commercial tracking data?
Should new spacecraft carry tracking aids?
Reflectors for radar or lasers?
Transponders?
What is the relationship of a civilian or commercial STM agency to the military? What is the flow of data? Can it task sensors?
Are self-conjunctions within a constellation treated differently by an external STM agency?

21. Collision Avoidance Maneuvers
Some questions to consider
Who should have responsibility to maneuver, and in what situation – who has the right of way?
Controlled vs. uncontrolled: ability to maneuver and avoid a collision
Different from live vs inert / operational vs. non-operational
Should there be “space lanes” with different rules?
There are different rules for air and sea traffic in different situations; e.g. restricted airspace near airports
Require active control or more rapid transit of “human zone”?
Special considerations for sun-synchronous orbits?
Should new spacecraft be required to be able to maneuver a minimum distance in a set amount of time?
If so, then what about upper stages?
How do we handle low-thrust (ion) maneuvering?
TLEs and VCMs (orbit data formats) have very limited ability to account for object acceleration
Low-thrust systems may be “untrackable” when under thrust

22. International Obligations and Liability
Some questions to consider
How will US treaty and international obligations affect US actions in STM?
How should the United States lead?
What services will be provided to non-US operators, and what will be the quid pro quo?
How or will US “rules” be practically extended to foreign operators?
Space debris: Are current mitigation guidelines sufficient?
Debris mitigation guidelines (25 year rule) did not include a huge population surge, and usually assumed nation-state actors
Will a “new space” company be in business in 25 years?
Insurance: should actors in space be required to insure against … ?
Second or third party liability?
Debris generation?
Should there be a “code of conduct?” What should a “prudent actor” in space do to avoid creating problems for other operators?
What is the responsibility of the launching company/agency/nation for the actions of the payloads?

23. For Discussion
Space operators’ business plans will be impacted by regulation, but regulations are not necessarily “bad”
Example: A regulation requires an active location transponder on all spacecraft
Negative impact: My cubesat design cannot accommodate that!
Positive impact: New market for my transponder package!
Some form of active space traffic management is probably inevitable
Safety, debris control will be primary motives
Will mostly focus on collision warning
Launch regulations and licensing restrictions will probably be primary mechanism
Will be aimed first at US businesses and agencies, but will likely set international precedents
What form should regulations take? When?
What should a responsible operator Code of Conduct contain?