Post on 11-Jan-2016
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A NANOSATELLITE MISSION TO ASSESS SOLAR SAIL PERFORMANCE IN LEO
Kieran A. Carroll, Gedex Inc.
Henry Spencer, SP Systems
Robert E. Zee, Space Flight Laboratory
George Vukovich, Canadian Space Agency
20-22 July 2010 A Nanosatellite Mission to Asses Solar Sailing Performance in LEOInternational Solar Sail Symposium 2010, New York
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Goals of This Presentation
• To introduce publicly the CanX-9 solar sail technology mission
• To convey a sense of the design approach that has been followed.
• To provide a starting point for coordinating this mission’s objectives with those of others who are working to mature solar sailing technology, e.g.:– IKAROS– Nanosail-D2– Lightsail-1– Cubesail
20-22 July 2010 A Nanosatellite Mission to Asses Solar Sailing Performance in LEOInternational Solar Sail Symposium 2010, New York
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Background: History of Solar Sailing in Canada
• 1978: Modi & Van Der Ha orbital dynamics papers (UBC)
20-22 July 2010 A Nanosatellite Mission to Asses Solar Sailing Performance in LEOInternational Solar Sail Symposium 2010, New York
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Background: History of Solar Sailing in Canada
• 1978: Modi & Van Der Ha papers• 1988-92: Canadian Solar Sail Project (CSSP)
– CCQJC Race to Mars– Canadian Space Society– University of Toronto Institute for Aerospace Studies
(UTIAS)– (Team members included Carroll and Spencer)
20-22 July 2010 A Nanosatellite Mission to Asses Solar Sailing Performance in LEOInternational Solar Sail Symposium 2010, New York
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CSSP Initial Design Concept
• Novel non-spinner• Hexagonal planform• “Venetian blind” sail vanes:
– Stowed rolled-up– Deployed and actuated by
cables• Compressive booms, each
60 m long• 500 kg, 10,000 m2
• Smallsat-class • Ariane 4 launch to escape
20-22 July 2010 A Nanosatellite Mission to Asses Solar Sailing Performance in LEOInternational Solar Sail Symposium 2010, New York
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CSSP Eventual Preliminary Design• Novel spinner• “Pinwheel” configuration• 30 vanes, each 30 x 0.5 m,
stowed and deployed roller-blind fashion
• 3 of the vanes with adjustable angle of attack for spin-rate control
• Precess spin vector (and hence sail pointing) direction via shifting mass center
• 25 kg, 500 m2
• Microsat-class• Scout or Pegasus launch to
escape
20-22 July 2010 A Nanosatellite Mission to Asses Solar Sailing Performance in LEOInternational Solar Sail Symposium 2010, New York
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Background: History of Solar Sailing in Canada
• 1978: Modi & Van Der Ha papers• 1988-92: Canadian Solar Sail Project (CSSP)
– CCQJC Race to Mars– Canadian Space Society– University of Toronto Institute for Aerospace Studies
(UTIAS)– Team members included Carroll and Spencer
20-22 July 2010 A Nanosatellite Mission to Asses Solar Sailing Performance in LEOInternational Solar Sail Symposium 2010, New York
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Background: History of Solar Sailing in Canada
• 1978: Modi & Van Der Ha papers• 1988-92: CSSP• 1990s: KAC @ Dynacon
– Polar Relay Satellite (POLARES) concept study:• ~100 kg polesitter for north pole region data backhaul• With SPAR, for Canadian DND• Heliogyro-like, with ~25 kg despun comms payload• (Independently conceived pole-sitter concept)
– Several solar sailing conference papers– Solar sail applications study for CSA– Supervised M.A.Sc. magnetosphere mission study
20-22 July 2010 A Nanosatellite Mission to Asses Solar Sailing Performance in LEOInternational Solar Sail Symposium 2010, New York
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Background: History of Solar Sailing in Canada
• 1978: Modi & Van Der Ha papers• 1988-92: CSSP• 1990s: KAC Dynacon solar sail activities• 1996-2003: MOST microsat mission for CSA
– Learned how to design and build microsats– UTIAS Space Flight Laboratory founded, major
subcontractor to Dynacon
20-22 July 2010 A Nanosatellite Mission to Asses Solar Sailing Performance in LEOInternational Solar Sail Symposium 2010, New York
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Background: History of Solar Sailing in Canada
• 1978: Modi & Van Der Ha papers• 1988-92: CSSP• 1990s: KAC Dynacon solar sail activities• 1996-2003: MOST microsat mission• 2000-2010:
– SFL nanosats– CanX program
20-22 July 2010 A Nanosatellite Mission to Asses Solar Sailing Performance in LEOInternational Solar Sail Symposium 2010, New York
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SFL’s CanX Program
• Canadian Advanced Nanospace eXperiment program
• Developing/flying significantly capable nanosats (1-10+ kg)
• Providing nanosat launch services via XPOD launcher i/f
• Current missions use the Generic Nanosat Bus (GNB) platform (20x20x20 cm)
20-22 July 2010 A Nanosatellite Mission to Asses Solar Sailing Performance in LEOInternational Solar Sail Symposium 2010, New York
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CanX-9 Mission Concept
• Fly a solar sail technology demonstrator using SFL nanosat technology
• Seek a partner to provide the solar sail subsystem• Demonstrate directed solar sail thrusting• Fly as a secondary payload in LEO• Expected total cost: <<$10M
20-22 July 2010 A Nanosatellite Mission to Asses Solar Sailing Performance in LEOInternational Solar Sail Symposium 2010, New York
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CanX-9 Programmatics• Initial preliminary design carried out at SFL• Partners include:
– Technology P.I. and Team• Source of mission requirements• Processes technology payload data to accomplish tech demo• Membership drawn from participating organizations
– SFL• Mission prime contractor• Bus and XPOD supplier• Arrange launch
– L’Garde• Provision of solar sail subsystem
– CSA• Supported initial design study• Considering funding the mission
20-22 July 2010 A Nanosatellite Mission to Asses Solar Sailing Performance in LEOInternational Solar Sail Symposium 2010, New York
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Mission Objectives
• Address issues impeding the use of solar sailing in operational missions
• Qualitative:– Demonstrate significant orbit changes via active solar sailing– Flight-test inflatable-boom square-sail technology
• Quantitative:– Determine sail reflectivity to within 1% by measuring orbit
changes– Determine changes in SRP force and torque with time
20-22 July 2010 A Nanosatellite Mission to Asses Solar Sailing Performance in LEOInternational Solar Sail Symposium 2010, New York
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Some Design Drivers/Issues• Cost drives use of nanosat
development approach:– Thus COTS EEE parts used– Radiation TID constraint drives
altitude limit to below 1000 km or above GEO
• Cost drives use of secondary-payload launch:– Secondary launch availability
constrains orbit availability and launch timing
– Sun-synchronous orbit preferred due to availability of launches, and resulting slowly-varying Sun-phase angle which simplifies some aspects of mission and system design
• Lack of available SRP torque actuators drives preference for low Earth orbit, thus 1000 km upper altitude constraint:– Strong Earth magnetic field in LEO
advantageous– Also reduces power for comms
• Atmospheric force/torque effects provide a 700 km (TBC) lower altitude constraint:– Issue: magnitude of these forces
and torques difficult to analyze in advance (“area of active research”)
– Will depend somewhat unpredictably on launch timing and Solar cycle phasing
20-22 July 2010 A Nanosatellite Mission to Asses Solar Sailing Performance in LEOInternational Solar Sail Symposium 2010, New York
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Mission and System Design
• Secondary payload launch using XPOD• Sun-synchronous orbit, 700-1000 km altitude• Sail area 25 m2 , mass <14 kg, mass/area ratio: <560
grams/m2 • Payloads for measuring orbit changes to determine
reflectivity to within 1% in 1 month• Use SFL UHF-up/S-band-down ground station• Quick-look payload data evaluation capability to support
day-to-day mission planning• Non-real-time analysis of payload data to accurately
estimate model parameters for solar radiation pressure and atmospheric forces
20-22 July 2010 A Nanosatellite Mission to Asses Solar Sailing Performance in LEOInternational Solar Sail Symposium 2010, New York
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XPOD Duo Launcher I/F• Developed for CanX-4/5 mission• Capacity:
– Designed to carry a dual-GNB bus– 20x20x40 cm– 14 kg
• Size (w/o spacecraft):– 47 x 47 x 52 cm– 10 kg
• Customizable• Relatively softer ride• Can accommodate fixed appendages
20-22 July 2010 A Nanosatellite Mission to Asses Solar Sailing Performance in LEOInternational Solar Sail Symposium 2010, New York
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Payloads• Solar sail subsystem
– Inflatable-boom square sail– To be provided by L’Garde
• Cameras– To provide deployment video– Boom-mounted to get far enough above sail plane for a good view
• GPS receiver– To provide low-frequency data on orbit changes– Flight heritage from CanX-2
• 3-axis accelerometer– To provide high-frequency data on orbit changes– Performance requirement: 10-7 m/s2 RMS accuracy at 0.01 Hz
• Total mass ~ 3 kg
20-22 July 2010 A Nanosatellite Mission to Asses Solar Sailing Performance in LEOInternational Solar Sail Symposium 2010, New York
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Satellite Design
• Bus– Thermal– OBC– Radios– Power– Structure– ACS
• Payloads– Solar Sail subsystem– Cameras + boom– GPS receiver– Accelerometer
Per existing GNB designs
Significantly modified GNB designs
New designs
20-22 July 2010 A Nanosatellite Mission to Asses Solar Sailing Performance in LEOInternational Solar Sail Symposium 2010, New York
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CanX-9 Bus
• To be developed by SFL• Mass ~ 12.5 kg
– Including sail support structure– Including 25% margin
• 20x20x40 cm main structure:– 20x20x20 cm lower bus– 20x20x15 cm upper bus– Sail stowed in 20x20x5 cm “sail-
box” layer between lower and upper bus sections
20-22 July 2010 A Nanosatellite Mission to Asses Solar Sailing Performance in LEOInternational Solar Sail Symposium 2010, New York
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CanX-9 With Sail Deployed
20-22 July 2010 A Nanosatellite Mission to Asses Solar Sailing Performance in LEOInternational Solar Sail Symposium 2010, New York
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Solar Sail Subsystem
• To be supplied by L’Garde• Miniaturized version of L’Garde
20m ground system demonstrator:– Square sail, 5.5m across flats,
25 m2 area– Four 4.1m inflatable booms,
thermally rigidized– Stripe-net support
• Mass ~ 1.5 kg (including 20% margin):– Sail: 0.2 kg– Booms: 0.3 kg– Deployment gear: 1.0 kg
20-22 July 2010 A Nanosatellite Mission to Asses Solar Sailing Performance in LEOInternational Solar Sail Symposium 2010, New York
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Attitude Control Subsystem
• Zero-momentum, 3-axis stabilized to 1 degree accuracy• Sensors:
– 9 Sun sensors on bus faces– 3-axis magnetometer on fixed boom– 3 angular rate sensors
• Actuators:– 3 magnetic torque rods– 3 reaction wheels
• All hardware and ACS software has CanX flight heritage• Mass ~ 1.75 kg, power ~ 4W
20-22 July 2010 A Nanosatellite Mission to Asses Solar Sailing Performance in LEOInternational Solar Sail Symposium 2010, New York
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Power Subsystem• Power Loads by Mode:
– Safe-Hold: 2 W– Detumble:2.5 W– Pre-deployment: 6 W– Deployment: 29 W– Post-deployment: 9 W
• Sail boom heaters and valves: – 14 W, for 1-2 orbits around
deployment time• Payload power:
– 2-3 W orbit-average• Transmitter power:
– 5 W, 100% duty cycle when sending down deployment video
• Power Supply– 45 pairs of ~ 27% efficiency (BOL) triple-junction solar cells– 27 pairs body-mounted– 18 pairs wing-mounted– Each with 920 mW max power generating capacity at worst-case-hot
temperature– 2x 20 W-hr Li-ion batteries
• Mass:– ~ 2.25 kg
20-22 July 2010 A Nanosatellite Mission to Asses Solar Sailing Performance in LEOInternational Solar Sail Symposium 2010, New York
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Thermal Subsystem• Mostly passive (careful choice of coatings)• Spot-heaters on some parts (battery, accelerometer)• Large heaters in sail booms, to raise their temperature prior to
deployment• Boom-to-bus insulation to keep booms from cooling too quickly
during deployment• Choice of boom epoxy, to have a glass transition temperature to
match bus worst-case-hot temperature• Analysis of Solar radiation incident on the bus versus sail orientation
with respect to the Sun:– Maximum reflected-Sunlight bus heating level of ~ 12W (versus direct-
incidence Sunlight ~ 35W)• Analysis of sail heating radiatively coupling into bus heating:
– Face-on to the Sun, the sail temperature can reach 150 C– This effect is largest when the reflected Sunlight effect is least