Active Removal of LEO Space Debris The Electro

Active Removal of LEO Space Debris: The Electro. Dynamic Debris Eliminator (EDDE) Jerome Pearson President, Star Technology and Research, Inc. jp@star-tech-inc. com FISO VTC for NASA Goddard Space Flight Center August 31, 2011 1

Co-Authors Eugene Levin Star Technology and Research, Inc. www. star-tech-inc. com Joe Carroll Tether Applications, Inc. www. tetherapplications. com 2

Unintended ASAT l LEO debris started acting as a slow-release random-target ASAT l The fallout from Cosmos-Iridium was very similar to Chinese ASAT test l 93% of tracked fragments are still in orbit l There are 30 -50 dangerous untracked fragments for each tracked one l The debris clouds have spread 1. 5 tons of ‘‘shrapnel’’ fragments ~1, 000 over 1 mm ~100, 000 potentially dangerous ~2, 000 trackable

Weapon of Mass Conjunctions l Tracked Fengyun-1 C fragments create ~600 conjunctions per day with satellites (range < 5 km) CSSI predictions for July 23, 2011: Spacecraft Min. range Rel. velocity 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 4 A F 4 243 m 14. 8 km/s 0. 08% Iridium 64 262 m 14. 9 km/s 0. 06% DMSP 5 B F 3 267 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-P 6 537 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 Impact prob. … 4

Clusters in LEO Risk measured as statistical yield of fragments: l l R = ∑ Mn • P n Highest risk of debris generation: 81 -83º cluster Highest number of satellites at risk: Sun-sync cluster % of fragmentation risk % of operational satellites Sun-sync 81 -83º 71 -74º Inclination, deg

Collision Risks l Sun-sync and 81 -83º clusters are threats to each other, increasing the risk of catastrophic collisions (Cosmos-Iridium type) Norm. avg. risk of a catastrophic collision Total Risk from 81 -83º cluster from Sun-sync cluster from 71 -74º cluster Inclination, deg

Head-on Traffic l The Sun-sync and 81 -83º inclination orbits precess in the opposite directions, align periodically, and create head-on traffic 82º 98º

Catastrophic Collisions l Collisions between large objects will release more and more ‘‘shrapnel’’ l Even small objects can smash satellites and rocket bodies into pieces in hypervelocity impacts Probability of a catastrophic collision per year 10% P ~ N 2, N ~ t 1960 1990 2020 year 3 U Cube. Sat 8

How Much to Remove l Risk measured as statistical yield of fragments: R = ∑ Mn • P n Risk of debris generation tons of debris removed l Small-scale removal won’t make a difference l We need wholesale removal 9

How Much to Launch l Wholesale removal of all spent stages and dead satellites l 2200 dead satellites and spent stages all over LEO, 2000 tons total l Too demanding for rockets: M = Md exp (ΔV / Ve) Estimated mass to launch, tons desired Isp, sec

Electrodynamic Propulsion l Propellantless, electrical, solar powered Electron emitter Geomagnetic field Conductor Ampere force Hollow cathode Electron collector Electrons Aluminum tape ● Circuit closing demonstrated in orbit by Plasma Motor Generator (PMG) in 1993 and Tethered Satellite System (TSS-1 R) in 1996 11

How to Think About It l Like sailing in the ionosphere on the “magnetic wind” Key West, 2006 12

Electrodynamic ‘‘Garbage Truck’’ l l l Electro. Dynamic Debris Eliminator (EDDE) Only 100 kg; two fit into one ESPA secondary payload slot Nano-satellites ‘‘taped’’ together, but can move tons Reinforced aluminum tape ESPA ring

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

Advantages of Spinning l l Spinning greatly improves stability and provides much better angles with the geomagnetic field ~15 min rotation period Deorbit rate with 1 -ton debris, km/day spinning hanging inclination, deg l EDDE is 10 times faster than conventional electrodynamic tethers in de-orbiting at high inclinations, where most debris resides

Test Flights l SEDS-1, NASA Marshall 20 km Spectra tether deployed from Delta II Sent the 26 -kg end-mass to controlled reentry l PMG (Plasma Motor Generator), NASA JSC 0. 5 km electrodynamic tether deployed from Delta II Demonstrated motor / generator operations Foundation for EDDE l SEDS-2, NASA Marshall 19. 7 km Spectra tether deployed from Delta II l Ti. PS, Naval Research Laboratory 4 km Spectra tether demonstrated 10 year lifetime All tethers and deployers by J. Carroll, TAI 16

EDDE Precursor Projects l Pro. SEDS, NASA Marshall 5 km electrodynamic tether to deorbit Delta II Was prepared to fly in 2003 l METS, Tether Applications 7. 5 km electrodynamic tether to boost Mir Was planned to fly in 2001 l TEPCE, Naval Research Laboratory 1 km electrodynamic tether, 3 U Cube. Sat In development to fly in 2012 l Tether. Sat, NRL and Naval Academy 1 km conductive tether, 3 U Cube. Sat In development to fly in 2012 All tethers and deployers by J. Carroll, TAI 17

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 ● 18

Net Capture l l 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 Tumbling debris object T Net T Conductor End-Body Net Manager

Robotic Capture l l 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 EDDE Payload manager T

Capture Trajectories 21

Wholesale Debris Removal

Commercial Service l 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

What Would It Take l If the IADC members decide to share the expense, it will be very low with electrodynamic removal l Competitive bidding for commercial debris removal services will stimulate technology and markets l 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 $M per Agency per year 10 8 6 old rocket bodies 4 old spacecraft 2 1 2 3 4 5 6 7 8 9 10 11 12 years ● IADC includes NASA, ESA, JAXA, DLR, CNES, CNSA, ISRO, UKSpace, ASI, CSA, Roscosmos, NSAU

Other EDDE Capabilities Besides removing debris, EDDE can also: l Deliver payloads to custom orbits l Deliver fuel to operational satellites l Deliver service modules to satellites l Deliver satellites to ISS for service l Move satellites to new orbits l Electrodynamic reboost of LEO facilities l Space weather monitoring all over LEO 25

Refueling and Servicing l EDDE can deliver fuel and service modules to satellites in LEO l Can provide high-delta-V propulsion for a LEO service vehicle l Can return a service vehicle to a fuel depot for refueling 26

Next Steps l Mature technology, select components, design segments and nodes Mini-EDDE Demonstration l Fly a scaled-down EDDE l Demonstrate large orbit changes in spinning mode l Test navigation, tracking, and active avoidance l Test rendezvous without capture Mission-Capable EDDE Fly piggyback on any flight with 100 -kg margin l Capture and drag down inactive US objects l 27