De-Orbiting of Satellites using Solar Sails Professor Vaios Lappas www.deorbitsail.com Space Vehicle Control Group Surrey Space Centre, University of Surrey Email: [email protected] Presentation Contents • The Problem: Space Debris and Debris/Satellite Deorbiting • DEORBITSAIL • The future: – DEPLOYTECH – InflateSAIL – Active Debris Removal Demonstration Mission Introducing Surrey…. Surrey Space Centre: formed in 1979 at the University of Surrey, pioneering microsatellites — now 90 academic researchers specialising in space engineering. Surrey Satellite Technology Ltd: formed in 1985 by the University of Surrey, is a British satellite manufacturing company; £40M revenues & 320 staff; SST-US in Denver, Co; EO services (DMCii); launch services; recently acquired by EADS. SSTL+SSC+ Astrium: achieving a synergy of academic research and commercial exploitation The University of Surrey • “Pushing the Boundaries of Low Cost Small Satellite Applications and Technologies” • Training the next generation of space engineers, scientists, entrepreneurs and business leaders • Hands-on education and research using in-orbit assets • Largest space engineering research group Surrey’s SNAP-1 6.5 kg SSC’s Ground-Station and Satellite Development Lab Nano-Satellite (2000) The Problem: Space Debris... The Problem: Space Debris • Satellites with a completed service Image courtesy of ESA/ESOC • Launch vehicle upper stages remain in space for years – Some explode due to depleted tanks • 5,500 tones of space debris in low earth orbit • Threat to: – Space assets – Astronauts/space stations – Environment • Space: Expensive Real-Estate – Earth observation, telecommunications, navigation Space Debris in LEO Image courtesy of ESA/ESOC Satellite/Space Debris Evolution ADR-Active Debris Removal Orbital Debris Distribution Operational payloads Non- • Largest portion (2/3) of orbital debris is 6% Fragments operational concentrated in LEO 40% payloads • Only 6% of Earth orbiting objects are 26% operational payloads Mission- Rocket • LEO altitude distribution shows peak at related bodies objects 780km 18% 10% Altitude Distribution in LEO 800 700 MEO Other 600 4% 8% 500 Highly 400 300 eccentric 200 orbits No. of objects No. of 100 11% LEO 0 67% 0 GEO 80 160 240 320 400 480 560 640 720 800 880 960 1120 1200 1280 1360 1440 1520 1600 1680 1760 1840 1920 1040 10% Altitude (km) 5 June 2011 Kick-off meeting 9 25 Year Deorbiting Requirement • Orbital debris mitigation guidelines have been debated in great detail in the space community. • In February 2007 and after a multi-year effort the United Nations' Committee on the Peaceful Uses of Outer Space (COPUOS) adopted a set of space debris mitigation guidelines which includes a 25 year deorbit requirement from LEO. • The guidelines were accepted by the COPUOS in June 2007 and endorsed by the United Nations in January 2008. • To become the law in many countries in Europe • Can we develop a simple, low cost deorbiting system for satellites or upper stages to stop the problem getting worse? • Can we clean up space from space junk? Deorbiting Technology for Debris Mitigation • There is a need to develop low cost, very compact passive/active deorbiting systems for satellites/upper stages • Developments/solutions/missions at Surrey: • Micro-electric propulsion (currently at TRL 3-7) • Cubesail: 3 kg, 5 x 5m drag sail mission funded by Astrium (launch 2012) • DEORBITSAIL: 4 kg, 5 x 5m drag sail funded-EU/FP7 (launch 2013-2014) • InflateSAIL: 4 kg, scalable 5.6m circular drag sail funded –EU (launch 2014) • Gossamer Deorbit system: 5 x 5m drag sail for deorbiting (ESA funded) • Active Debris Removal mission using tether/net/dragsail using nanosats • Using low cost, practical solutions, based on COTS; in orbit demonstration using cubesat technology/nanosatellite missions DEORBITSAIL Mission Objectives • Demonstrate deployment of 25 m2 solar sail (~5m x 5m) • Test satellite deorbiting – Use drag for deorbiting • Test Solar Sail propulsion – Change in inclination ≈ 2°/year in 800 km orbit • Implement a 3-axis active ADCS to align sail to orbit plane for minimum drag in LEO • Measure solar force over a minimum 1 year period • Funded by EU FP7 (Space Call) • Launch date: 2013 • Complete spacecraft specifications: 3U Cubesat, 4 kg, 10 x 10 x 30 cm The Team The Technology Deployment System Concept Cubesail Concept • Back-to-back tape measures for booms • 4x booms coiled around a centre spindle • Sail membrane attached to boom ends and lifted above the coiling plane • Simple, robust, ultra-light (< 2 kg) Sail Deployment Subsystem Control electronics Batteries CubeSat base • 1.7x1.7m 4-Quadrant Sail Central Shaft prototype • 4 x1.3m 0.3mm Co-coiled Booms Sail membrane (two tape-springs held front-to- front) Membrane spindle • In-house heat-treatment of Becu flat strips to provide curvature 25mm boom • Coated with aluminized Kapton Spindle release tube (sheath) for thermal control Deployment on the Airbearing Cubesail Deployed 1.7 x 1.7 m sail Improved 1.7 x 1.7 m Sail DEORBITSAIL: ‘Drag Mode’ • In Drag-Sail mode the deployed membranes will be used to increase the area of the spacecraft • It will interact with the atmospheric particles, causing an increase in drag and result in a more rapid deorbiting. DEORBITSAIL: ‘Solar Sail’ • Use of photons from the Sun (free!) • Build up of a significant velocity (continuous reflection of photons) in time • ‘Propellant-less’ propulsion system DEORBITSAIL ’Bus’ Concept • 3U CubeSat form factor (10 x 10 x 34cm) • 10 x 10 x 10 cm unit keeps housekeeping subsystems – Power, RF link, on-board computer • Use PPOD deployer – Low risk – Plenty of launch opportunities Satellite Bus-Cubesat 3U Deorbitsail: Current Status • In Year 1 of project (M10) • Completed: – Literature/technology survey – Mission requirements, thermal analysis, ADCS analysis • In process: – Conceptual design – Sail/subsystem design • Near term: – PDR (end of 2012) – Engineering Model (end of 2012) Future Work • 3 Nanosatellite missions – Cubesail, 5 x 5m sail, launch in 2012, funded by Astrium – DEORBITSAIL, 6 x 6m sail, launch in 2013, funded by EU – InflateSAIL, cool gas inflatable sail, funded by the EU (DEPLOYTECH and QB50) • ESA Project: Gossamer DEORBITER • Active Debris Removal – Cubesail/nanosatellite mission using a tether/net to capture debris, docking, deorbiting with sail Inflatesail 5.6 m diameter Mylar or CP-1 3 x 7 m booms for deployment 3U Cubesat Deployable arrays EU Funding: DEPLOYTECH, QB50 Small Satellite Deorbiting System 10 x 10 x 15 cm Sail Container 12 x 12 x 15 cm Deployment System 30 cm 30 cm height Small Satellite Deorbiting System Deployed Small Satellite Deorbiting System Stowed Electric Propulsion • SSC: 5 vacuum chambers, 2 thrust balances (1-20 mN, 0.1 mN acc.) Micro-Pulsed Plasma Hollow cathode thruster Quad Confinement Thruster Helicon Double Layer Thruster Experimental unit to be Target spec Thruster. Target spec -1.2-4.3 µN flown on SSTL’s – 650 sec Isp -600 sec Isp -50-185secIsp TechDemoSat-1 (2011) – 3.8 mN thrust -10 mN thrust -STRaND nanosat -1-2 mN, 200sec Isp – 200 W power < 1kW power -flight in 2011 -In house avionics –Thrust Vector Control -No grids -TRL 7 -TRL 5-7 –TRL 3 -TRL 3-5 Conclusion • DEORBITSAIL: – A unique, low cost space mission tackling the Space Debris problem – Simple and innovative design – Practical, in-orbit demonstration – Solar Sailing • Space Debris, an important issue – Protecting the space environment – Protecting space assets – Public is very interested: BBC, Economist, De Spiegel, New Scientist, Le Monde, Times… .