The Oculus. A Nanosatellite for Space Situational Awareness. Project Manager Phil Hohnstadt. Principle Investigator Dr. Brad King

Transcription

1 The Oculus A Nanosatellite for Space Situational Awareness Principle Investigator Dr. Brad King Project Manager Phil Hohnstadt Lead Systems Engineer Tom Venturino

2 University Nanosatellite Program Two year student satellite competition hosted by the AFRL, AFOSR, and AIAA Educate and train students for future work in the satellite technology 11 universities currently participating ~$100,000 budget SHOT I & II Workshops, SatFab Workshop SCR, SRR, PDR, CDR, PQR, FCR The winning vehicle receives a launch opportunity

3 The Aerospace Enterprise Replacement to a Senior Design/Capstone project Students are involved for at least 2 years Allows for larger, more complex projects Student run programs operating like a real business Multidisciplinary Teams Emphasizes teamwork, student leadership and realistic experience

4 Student Involvement Students: Develop initial concepts Create detailed designs Perform FEA, thermal, and pressure profile analyses Fabricate satellite components Resolve design and integration issues Execute component and system level testing including functional testing, vibrations testing, and thermal vacuum testing Are responsible for project management, budgeting, and personnel resources

5 Primary Mission The Oculus mission is to aid in the advancement of U.S. Space Situational Awareness by providing a vehicle capable of space to space imaging as well as being a telescope calibration target of known physical characteristics and attitude. Demonstrate a nanosatellite platform capable of space to space imaging Autonomously track and monitor CubeSats released from Oculus ASR using NFOV and WFOV imagers Evaluate algorithms to detect, acquire, and track RSOs of opportunity Controlled viewing opportunities for ground telescope facilities seeking to determine the properties of an orbiting object Provides opportunity to test the functionality of instruments and algorithms

6 Current Vehicle

7 WFOV Imager SAIC space qualified Microspace camera Close proximity operations Monitor and confirm release of imaging targets Sensor Format Full Well Pixel Size A to D Converter Output Data Format Frame Rate Integration Time 752 x 480 pixels CMOS 20K e, Linear 6 μm x 6 μm 10 bits LVDS Serial (Channel Link) 0.2 to 60 Frames/ Second Commandable: 88 μsec to 5 sec

8 NFOV Imager Sensor Format Pixel Size Imaging Area Frame Rate at Full Resolution Digitization 1024 x 1024 frame transfer, back illuminated EMCCD 13 μm x 13 μm 13.3 x 13.3mm 8.5 fps 10, 5, and 1 bits Lens 200 mm f/2.8 lens Ruggedized for Space Fixed movable components Replace iris with fixed aperture Locked autofocus to infinity Vented closed compartments Structurally reinforced

9 Image Tracking 3 axis attitude control system developed on established reaction wheel and magnetorquer control laws as well as a Kalman filter driven attitude estimator Visually referenced onboard image recognition and tracking software Control system modeled and developed with Simulink Simulations conducted with 6 DOF Stewart Platform Operates on embedded PC104 computer

10 Structure Octagonal prism made of isogrid panels with internal bracing for added structural support and mounting points Primary material is alodined 6061 aluminum FEA, Thermal Analysis, Experimental Modal Vibration testing has been performed Current vehicle has first resonance of 162 Hz; with additional module this will still remain well above 100 Hz Operational temperature range of 20 C to 50 C Two releasable imaging targets using a cup cone interface with the main vehicle

11 Power Solar Cells Emcore advanced triple junction cells Generate an orbit average of 20W String voltage of 38V and current of 0.45A Attached to aluminum honeycomb with 7mm standoff from satellite structure MLI provides thermal insulation between structure and solar cell substrate Batteries Space rated lithium ion battery from ABSL Power Three parallel strings of cells String consists of eight 4.2 V, 1.5 amp hr Sony 1860HC cells 33.6V, 4.5 amp hr battery with a capacity of 125 Watt hrs Power Distribution Regulated voltages of 3.3V, 5V, 12V and 24 V Voltage lines utilize PTC fuse protection

12 Onboard Data & Command Two MIP405 computers used for GNC algorithms, command and communication, health data, and imaging Radiation tested and used on the International Space Station Form Factor Processor RAM Buses Ports Clock Features Operating System Support PC104+ PowerPC 400 MHz 128 MB ECC PCI, ISA Ethernet, Serial, IDE Real Time backed with battery, Independent Watchdog Timer VxWorks, Real Time Linus MIP405 Processing Connected to an FPGA, a 32 GB solid state hard drive, and two frame grabbers Frame grabbers communicate with WFOV and NFOV imagers for data acquisition

13 Telecommunications Command and Control Requires 600 bits per second throughput Hamtronics TA 451 transmitter radio operating on a 2 meter wavelength Hamtronics R144 receiver radio operating on a 70 cm wavelength A Comtelco 144 MHz antenna and a Comtelco 440 MHz antenna mounted on the same side panel with nulls at ±15 and 180 off bore sight provide communication in almost any orientation. Image Transmission 160,000 bits per second throughput Microhard Systems MHX 2420 radio operating at 2.4 GHz Comtelco 2.4GHz patch antenna with a ±15 beam width and 14dBi gain Uses Advanced Encryption Standard

14 Guidance Navigation and Control Magnetometer Attitude Determination: Bartington Instruments Mag 03MRN space rated fluxgate magnetometer LEO flight heritage Magnetic field angular sensing error of 1.0 deg Gyroscopes Drift of 5 deg/min Silicon Sensing RRS01 radiation tested MEMS 50 deg/s angular rate gyros European Space Agency flight history Analog Devices ADIS16365 redundant MEMS gyros

15 Guidance Navigation and Control Attitude Control Actuators: Reaction Wheels Designed, built, and tested at MTU 84mm diameter brass wheel with 385 kg mm 2 inertia Top Speed 10,000 rpm Torque 0.01 N m Balanced by Precision Balancing Company to at least 0.1 grams on center Magnetorquers Designed, built, and tested at MTU Annealed Hiperco 50A cores Approximately 2,000 turns generate a 10.0 amp turn m 2 maximum powered dipole with a amp m 2 remnant dipole when subjected to a 300mA current

16 Oculus ASR Structure ASR Module Retroreflector for vehicle ranging measurements Deployable side panels for changing vehicle shape and exposing additional materials Physical Envelope: 42.51cm x 42.51cm x 30.00cm A Frangibolt actuator will fracture the bolt holding the deployable panel. Each panel will be covered in a different material Currently investigating: Anodized Aluminum Gold Foil Thermal Paints Mylar Kapton Lightband bolt hole pattern Retroreflector Patch antenna 16

17 Conclusions The University Nanosat Program: Has educated students in small satellite development Prepared students for internships and careers in space technology The Oculus: Can help to confirm the viability of a constellation of small, space to space imaging satellites to compliment groundbased observatories Will aid in the calibration of smaller, more inexpensive ground based telescopes Ultimately has the potential to aid in the advancement of U.S. Space Situational Awareness

18 Questions? 18