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Near Earth Asteroid Detection System

Near Earth Asteroid Detection System. Technology Validation Mission Design Review. AERO 426 – Space Systems Design. Advisor Dr. Hyland. Project Manager Jesus Orozco. Assistant Project Manager Jeff Campbell. Table of Contents. Overview. Background Information Mission Statement

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Near Earth Asteroid Detection System

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  1. Near Earth Asteroid Detection System Technology Validation Mission Design Review AERO 426 – Space Systems Design Advisor Dr. Hyland Project Manager Jesus Orozco Assistant Project Manager Jeff Campbell

  2. Table of Contents

  3. Overview • Background Information • Mission Statement • Introduction • Requirements • Mission Overview • Observation Candidates & Performance Evaluation Group • Light Gathering Optics Design Group • Formation Design Group • GNC & Communications Group • Propulsion Group • Power & Thermal Group • Structures Group • Budget & Schedule • Conclusions

  4. Background Information • Many objects hit Earth all the time • Sometimes these objects are large enough we can notice them and they can cause damages • Chelyanbinsk February 15, 2013

  5. Conventional Method of Observing Basic technique: A set of observers note the time and duration that a star disappears from sight. Then plot the ground track of the asteroid during the occultations and get the asteroid shape (silhouette) This seems very straightforward, so what’s left to learn? Answer: The simple technique assumes the asteroid is big enough (10s to 100s of km) to cast a sharp shadow. “Small” asteroids (like Apophis) may create “interference patterns”, not well defined shadows! 5

  6. NEA Detection Summary Only 1% detected, and if you wait for sharp shadows, it’s probably too late

  7. Stellar Occultation System Array of light collecting apertures, each equipped with a photo detector Distant star Shadow pattern Resolved silhouette Phase Retrieval algorithm Huygens Fresnel Inversion

  8. Mission Statement The mission objective is to validate advanced stellar occultation technology capable of detecting small, potentially hazardous Near Earth Asteroids.

  9. Top-Level Requirements • Address the complete system, including the CubeSats, their formation, data links, ground system, etc. • Each CubeSat must host a 10cm diameter telescope and light intensity detector. • Assume visible light with wavelength centered at 0.5 µm • Plan for a minimum of 12 and a maximum of 96 CubeSats. • Ground station in CS

  10. Top-Level Requirements • Deploy the CubeSats in LEO with orbit lifetime no greater than 18 months • CubeSat array must be capable of recording the shadow pattern of a 40m asteroid at 1 AU distance • Intensity detectors should be capable of recording light from a 12th magnitude star with Signal-to-Noise Ratio (SNR) of at least 10. (~80 observations possible). • Obtain silhouette of asteroids in the 40 to 140m range with at least 10 pixels across. • Cost < $15M

  11. Design Results • Two satellite designs: Optic and Master • 15 Optic Satellites, 1 Master • Y-formation in Low Earth Orbit at 450km • Independent Pegasus Launch • Deployable Cassegrain Optic with photodiode

  12. Optic Satellite Master Satellite

  13. Mission Overview • Planning & Development • Production • Initial Launch • Normal Mission Operations • End-of-life Disposal

  14. Observation Candidates Technical Group Lead John Maksimik Team Members Ramon Calzada Kimberly Ellsworth Jordan Heard Kristin Nichols Jesus Orozco

  15. Observation Candidates • Technology: occultation of asteroid within 40 -140 m diameter • Technology Validation: Most known occultations involve large asteroids • Although the technology will be validated on larger asteroids, the array is sized for 40 – 140 m • Instead of occulting a large asteroid, we will occult the first ripple coming off of the shadow of the asteroid • Use the shadow data to determine the distance to the asteroid and the diameter of the asteroid • Adequate SNR is necessary to observe the shadow ripples

  16. Shadow Ripple • The length of the first ripple is proportional to where is the distance to the asteroid and is the wavelength. • The intensity height of the first ripple is used to find the size of the asteroid. • Occultations by the Moon are also possible. Intensity Length

  17. Signal to Noise Ratio *Diameter- circular distance around array Constant array width of 3.75km Dark count of 365kHz total

  18. List of Asteroids

  19. List of Asteroids

  20. 241 Germania Ripple length: 427 m Date: 22 Jan 2014 Caribbean, Mexico Star: TYC 1354-00434-1 mag 9.4 Diameter: 184 km

  21. Light Gathering Optics Technical Group Lead Chris McCrory Team Members Emily Boster Jeffrey Campbell Daniel Charles Joseph Duggan VianniRicano

  22. Solid works model

  23. Zemacs Optical Design • Boom Length • Primary Mirror Diameter • Focal Length • Distance between primary and focal plane • Secondary diameter • Radii of curvature of primary and secondary mirrors • Spot Diagram

  24. Cassegrain Telescope Distance Between Mirrors: 30.0 cm Distance Between Primary and Photodiode: 3.0 cm Focal Length: 6.0 m 11/26/2013

  25. Spot Diagrams

  26. SensLMiniSM Silicon • Photomultiplier 30035 series • Avalanche Photodiode set in Geiger mode

  27. Photomultiplier • Built in Peltier thermoelectric cooling system • Coaxial Cable

  28. Formation Design Group Technical Group Lead Joshua Kinsey Team Members Hope Russell Candace Hernandez Jose Long Brian Musslewhite BrigidFlood

  29. 10 pixels Formation 120° 120° 120° 10 pixels

  30. Euler Hill Reference Frame

  31. Euler Hill Approximation Non-dimensionalized equations of motion for the perturbing force in the local Hill frame: Solution for Force Free Motion and Impulse Conditions:

  32. Euler Hill Approximation

  33. Formation Deployment 120° 120° 120°

  34. Cube Sate Delta-V Calculation • Thruster Specs • Propellant volume = 95 cm3 • Propellant density = 0.556 g/cm3 • Isp = 65 sec • Maximum Mass (full Cube Sat) = 4 kg • Δvmax = 8.411 m/s

  35. Station Keeping • Perturbations for LEO orbits • Atmospheric Drag • J2 Effect • Only J2 Effect considered for station keeping calculations • Orbit eccentricity determined by Maximum Radial Component of Formation Width divided by Nominal Orbit Radius • Delta-Vs for 1 year is 0.0496km/s • Δm/m = .00036%

  36. Deployment Vehicle Delta-V Calculation • Assumed a simple two body rendezvous problem and a designed elliptical orbit • Calculated using conservation of energy: • Delta-V values ranged from 350.332 m/s to 350.362 m/s a b

  37. GNC & Communications Techincal Group Lead Josh Jennings Team Members Chris Cederberg Ken Cundiff Nicholas Gawloski Kristina Loftin Michael Young

  38. GNC – Control Package • Blue Canyon XACT • Complete GNC Package • Reaction Wheels • Torque Rods • Sun Sensors • Star Tracker • IMU • Magnetometer • GPS • Pointing Accuracy: 0.007° • $110,000 (with GPS) • Whole system not flight tested, just the star tracker Blue Canyon XACT

  39. GNC – Control Package • Issues • Very expensive; propagated over many craft • Need extremely high pointing accuracy • Conclusions • XACT meets minimum specifications • Will use XACT for GNC

  40. GNC – Dynamics Control Verification • Control Response from Simulink • PID Control using Reaction Wheels in XACT • Rotated to some arbitrary angles • Shows ability of XACT Reaction Wheels to change orientation of 3U cubesat • Does not factor in environmental disturbances

  41. Telecommunications • Downlink: Mother Sat to Earth • S-Band Transmitter w/ patch antenna • Gain: 8 dBi • Beamwidth: 60° • 2.4 - 2.483 GHz • 1 Mbps • Link Margin: 6.1 dB

  42. Telecommunications • Uplink: Earth to Mother Sat • ISIS VHF downlink / UHF uplink Full Duplex Transceiver • Frequency • UHF: 400-450 MHz • 9600 bps • Deployable UHF/VHF antenna • UHF Gain: -6 dBi

  43. Link Budget

  44. Telecommunication • Crosslink: Eye Sat to Mother Sat • ISIS UHF downlink / VHF uplink Full Duplex Transceiver • Frequency • UHF: 400-450 MHz • 9600 bps • VFH: 130-160 MHz • 1200 bps • Deployable UHF/VHF antenna • UHF Gain: -6 dBi • VHF Gain: -5 dBi

  45. Link Budget Cross LinkUHF/VHF

  46. Propulsion Technical Group Lead Evan Siracki Team Members Fernando Aguilera John Albers Randall Reams Nicholas Matcek James Kim

  47. Launch VehiclePegasus XL • 443 kg payload into LEO • Launch cost - $11 million • Diameter - 1.27 m • 88% success rate • 100% success rate since 1996. • Allows for direct insertion into orbit

  48. CubeSat Propulsion • Most of the cubesats currently in orbit do not have an active propulsion system. However, in order to keep our cubesatsin formation small amounts of thrust are required to compensate for translational perturbations. This is necessary to allow for formation flying.

  49. VACCO Micro-Thruster • VACCO/JPL Butane Micro-Thruster • Cold gas thruster • 5 multi-directional thrusters, ideal for translational perturbation corrections • Low power consumption: 100mW-4W peak • Low mass: 509g (50 g of propellant) • Low Isp: 70s • Vacuum tested but not flight tested

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