Active Removal of LEO Space Debris: The ElectroDynamic Debris Eliminator (EDDE) Jerome Pearson President, Star Technology and Research, Inc. [e-mail]

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Active Removal of LEO Space Debris The
ElectroDynamic Debris Eliminator (EDDE)Jerome
PearsonPresident, Star Technology and Research,
Inc.jp_at_star-tech-inc.com

• FISO VTC for NASA Goddard Space Flight Center
• August 31, 2011

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• Co-Authors
• Eugene Levin
• Star Technology and Research, Inc.
• www.star-tech-inc.com
• Joe Carroll
• Tether Applications, Inc.
• www.tetherapplications.com

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Unintended ASAT

• LEO debris started acting as a slow-release
  random-target ASAT
• The fallout from Cosmos-Iridium was very similar
  to Chinese ASAT test
• 93 of tracked fragments are still in orbit
• There are 30-50 dangerous untracked fragments for
  each tracked one
• The debris clouds have spread

1.5 tons of shrapnel
fragments
1,000,000 over 1 mm
100,000 potentially dangerous
2,000 trackable
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Weapon of Mass Conjunctions

• Tracked Fengyun-1C fragments create 600
  conjunctions per day with satellites (range lt 5
  km)

CSSI predictions for July 23, 2011
Spacecraft Min. range Rel. velocity Impact prob.
Meteor 1-21 78 m 13.9 km/s 0.8
Cosmos 367 92 m 9.0 km/s 0.4
Meteor 1-23 144 m 14.8 km/s 0.2
DMSP 4A F4 243 m 14.8 km/s 0.08
Iridium 64 262 m 14.9 km/s 0.06
DMSP 5B F3 267 m 12.5 km/s 0.005
NOAA 14 318 m 6.5 km/s 0.02
GOSAT 370 m 12.7 km/s 0.003
Cosmos 676 409 m 9.6 km/s 0.004
IRS-P6 537 m 11.9 km/s 0.001
Explorer 22 540 m 14.9 km/s 0.002
Landsat 5 556 m 8.4 km/s 0.005

celestrak.com
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Clusters in LEO

• Risk measured as statistical yield of fragments
  R ? Mn Pn
• Highest risk of debris generation 81-83º
  cluster
• Highest number of satellites at risk Sun-sync
  cluster

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Collision Risks

• Sun-sync and 81-83º clusters are threats to each
  other, increasing the risk of catastrophic
  collisions (Cosmos-Iridium type)

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Head-on Traffic

• The Sun-sync and 81-83º inclination orbits
  precess in the opposite directions, align
  periodically, and create head-on traffic

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Catastrophic Collisions

• Collisions between large objects will release
  more and more shrapnel
• Even small objects can smash satellites and
  rocket bodies into pieces in hypervelocity impacts

Probability of a catastrophic collision per year
10
P N2, N t
1960
1990
2020
year
3U CubeSat
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How Much to Remove

• Risk measured as statistical yield of fragments
  R ? Mn Pn

Risk of debris generation
tons of debris removed

• Small-scale removal wont make a difference
• We need wholesale removal

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How Much to Launch

• Wholesale removal of all spent stages and dead
  satellites
• 2200 dead satellites and spent stages all over
  LEO, 2000 tons total
• Too demanding for rockets M Md exp (?V / Ve)

Estimated mass to launch, tons
desired
Isp, sec
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Electrodynamic Propulsion

• Propellantless, electrical, solar powered

Electron emitter
Hollow cathode
Electron collector
Aluminum tape

• Circuit closing demonstrated in orbit by Plasma
  Motor Generator (PMG) in 1993 and Tethered
  Satellite System (TSS-1R) in 1996

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How to Think About It

• Like sailing in the ionosphere on the magnetic
  wind

Key West, 2006
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Electrodynamic Garbage Truck

• ElectroDynamic Debris Eliminator (EDDE)
• Only 100 kg two fit into one ESPA secondary
  payload slot
• Nano-satellites taped together, but can move
  tons

ESPA ring
Reinforced aluminum tape
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Modularity and Survivability

• Various configurations can be assembled from
  standard segments and nodes
• All thrusting segments can be controlled
  independently
• High maneuverability and propellantless thrust
  allow avoidance of all tracked objects by wide
  margins
• Probability of a conductor cut by an untracked
  object or micrometeoroid is much lower than
  typical probability of failure of spacecraft
  avionics
• Even if cut, both segments remain fully
  controllable and can deorbit themselves in days,
  avoiding all other objects

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Advantages of Spinning

• Spinning greatly improves stability and provides
  much better angles with the geomagnetic field
• 15 min rotation period
• EDDE is 10 times faster than conventional
  electrodynamic tethers in de-orbiting at high
  inclinations, where most debris resides

Deorbit rate with 1-ton debris, km/day
spinning
hanging
inclination, deg
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Test Flights

• SEDS-1, NASA Marshall
• 20 km Spectra tether deployed from Delta II
• Sent the 26-kg end-mass to controlled reentry
• PMG (Plasma Motor Generator), NASA JSC
• 0.5 km electrodynamic tether deployed from Delta
  II
• Demonstrated motor / generator operations
• Foundation for EDDE
• SEDS-2, NASA Marshall
• 19.7 km Spectra tether deployed from Delta II
• TiPS, Naval Research Laboratory
• 4 km Spectra tether demonstrated 10 year lifetime

All tethers and deployers by J. Carroll, TAI
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EDDE Precursor Projects

• ProSEDS, NASA Marshall
• 5 km electrodynamic tether to deorbit Delta II
• Was prepared to fly in 2003
• METS, Tether Applications
• 7.5 km electrodynamic tether to boost Mir
• Was planned to fly in 2001
• TEPCE, Naval Research Laboratory
• 1 km electrodynamic tether, 3U CubeSat
• In development to fly in 2012
• TetherSat, NRL and Naval Academy
• 1 km conductive tether, 3U CubeSat
• In development to fly in 2012

All tethers and deployers by J. Carroll, TAI
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Technology Status

• No breakthroughs required

Component Status
Electrodynamic propulsion Demonstrated in space
Bare surface electron collection Demonstrated in space
Hollow cathodes Flown multiple times in use on ISS
Thin film solar arrays Tested in space
Bare tape collectors Tested extensively in vacuum
Tether deployment Demonstrated in space
GPS, sensors, electronics Many models on the market
Control algorithms software Tested in simulators

• NRL Tether Electrodynamic Propulsion Cubesat
  Experiment (2012)
• An early prototype of the EDDE segment and nodes

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Net Capture

• Each Net Manager holds 100 house-size nets, 50 g
  each
• Passes at 2-3 m/s, captures debris in a net, and
  drags it to storage or short lived orbit below
  ISS
• Tension induced by EDDE rotation detumbles and
  stabilizes the object
• Indifferent to shapes and sizes

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Robotic Capture

• EDDE drops off a small robotic module in close
  proximity to debris
• It attaches to a selected part (nozzle) and
  extends capture interface
• EDDE approaches and grabs the capture interface
• Tension induced by EDDE rotation detumbles and
  stabilizes the object

Robotic module
Capture interface
Payload manager
EDDE
T
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Capture Trajectories
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Wholesale Debris Removal
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Commercial Service

• The cost of removal must be much lower than
  launch costs per kg to make economic sense

Cost per kg of debris removed
tons of debris removed
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What Would It Take

• If the IADC members decide to share the expense,
  it will be very low with electrodynamic removal
• Competitive bidding for commercial debris removal
  services will stimulate technology and markets
• Governments exit after large legacy debris are
  removed, rules are set for prompt removal of
  upper stages and failed satellites, and
  commercial debris removal services are in place

• IADC includes NASA, ESA, JAXA, DLR, CNES, CNSA,
  ISRO, UKSpace, ASI, CSA, Roscosmos, NSAU

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Other EDDE Capabilities

• Besides removing debris, EDDE can also
• Deliver payloads to custom orbits
• Deliver fuel to operational satellites
• Deliver service modules to satellites
• Deliver satellites to ISS for service
• Move satellites to new orbits
• Electrodynamic reboost of LEO facilities
• Space weather monitoring all over LEO

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Refueling and Servicing

• EDDE can deliver fuel and service modules to
  satellites in LEO
• Can provide high-delta-V propulsion for a LEO
  service vehicle
• Can return a service vehicle to a fuel depot for
  refueling

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Next Steps

• Mature technology, select components, design
  segments and nodes

Mini-EDDE Demonstration

• Fly a scaled-down EDDE
• Demonstrate large orbit changes in spinning mode
• Test navigation, tracking, and active avoidance
• Test rendezvous without capture

Mission-Capable EDDE

• Fly piggyback on any flight with 100-kg margin
• Capture and drag down inactive US objects