Hokie Sat Introduction Daniel Pedraza Systems Operations

Hokie. Sat Introduction Daniel Pedraza Systems & Operations Hokie. Sat dpedraza@vt. edu 22 August, 2002

Overview 1. Introduction 2. Mission & System Overview 3. 3 CS Mission 4. ION-F Mission 5. Design/Configuration 6. Structure/Mass 7. Propulsion 8. Testing

Mission and System Overview • Air Force Research Laboratory (AFRL) – “Tech. Sat-21” • Investigate small, distributed spacecraft systems • Missions of larger, single platforms • University Nanosatellite Program (UNP) – Purpose: • help explore and implement technologies of small satellites • 10 schools

Participating Universities Nanosat-1 Nanosat-2 Emerald Orion ION-F 3 -Corner Sat

Mission and System Overview • VT-ISMM – Virginia Tech Ionospheric Scintillation Measurement Mission – Single satellite investigation – Design quickly integrated with: • Utah State University • University of Washington • VT-ISMM =====> ION-F

Mission and System Overview • ION-F Formation Flying Mission – – – NASA-Goddard Space Flight Center (GSFC) Many algorithms developed at GSFC Earth Observer 1 (EO-1) flies with Landsat 7 Three (3) satellites with propulsive capabilities Demonstrate more involved formation flying routines

Nanosat-2 Brief Milestone Schedule Dec 01 Sep 01 Jun 01 Mar 02 04 -06 April 01 CDR 25 May 01 (est. ) Phase 0/1 Safety Review Phase 2 Safety Package Development Phase 3 Safety Package Development 15 July 01 MSDS Fabrication 01 December 01 Nanosat Delivery Integration and Test

University Nanosatellite Program Overview University Nanosatellites DESCRIPTION Nine U. S. universities are producing nine nanosatellites. The nanosats will be deployed via 2 flight missions from Space Shuttle SHELS hardware (Nanosat-1 and Nanosat-2) The nanosats are organized into 3 subclusters for the purposes of demonstrating formation flying, intersatellite collaborative processing/ communication, and autonomous control operations and data downlink Each nanosat cluster incorporates unique technology demonstrations and science measurement capabilities • Sponsors: Air Force Research Labs, NASA’s Goddard Flight Center AFRL Multi. Satellite Deployment System (MSDS) NASA Shuttle Hitchhiker Experiment Launch System (SHELS)

3 CS Introduction/System Three Corner Sat Introduction/Systems Arizona State University New Mexico State University of Colorado at Boulder

3 CS Mission • 3 universities working together to develop constellation of 3 identical satellites • ~2 year development schedule • Launched as stack on NASA Space Shuttle • Each university emphasizing its past heritage • Innovative, low-cost solutions & development encouraged

3 CS Mission Objectives • Inter-satellite Communications • Virtual Formation Flying • Distributed & Automated Operations • Imaging • Modular, Generic Design • Micropropulsion Experiment • Student Education

ION-F Introduction/Systems Virginia Tech University of Washington Utah State University

ION-F Mission • Investigate satellite coordination and management technologies and distributed ionosphere scintillation measurements • Coordinate on satellite design, formation flying, management mission development, science instruments, mission • Design and implement internet-based operations centers, enabling each university to control its satellite from a remote location

Mission Configuration: 3 CS ION-F USUSat Dawgstar Scenario: Hokie. Sat Multiple Satellite Deployment System

Separation Scenarios

Multiple Satellite Deployment System (MSDS)

Leader / Follower Formation Orbit Ground Track

Same Ground Track Formation Orbit Ground Track

Design Hokie. Sat • 18. 25” (~ 45 cm) major diameter hexagonal prism • 12” tall (30 cm) • 39 lbs (~18 kg) • Isogrid Structure • Composite Side Panels – 0. 23” isogrid – 0. 02” skins

External Configuration Crosslink Antenna GPS Antenna Solar Cells Light. Band Pulsed Plasma Thrusters Data Port Camera Science Patches Downlink Antenna Uplink Antenna

Internal Configuration Cameras Torque Coils (3) Camera Crosslink Components Power Processing Unit Magnetometer Pulsed Plasma Thrusters (2) Camera Battery Enclosure Rate Gyros (3) Downlink Transmitter Electronics Enclosure

VT Structures Overview

Hokie. Sat Structure Panel 6 Panel 5 Panel 4 Panel 1 Panel 2 Panel 3 Nadir/Zenith Panel

Hardware • Description: Nadir and Zenith • Heritage: None • Manufacturer: In-House/Techsburg • Properties: Al 6061 T-6, Class 3 Irridite (MILC-5541 -E) • Mass: 1. 70 lbm (0. 773 kg) • Status: Prototype Complete Ø 0. 190 x 3 Thru

Mass Total Mass = 16. 6 lbm (7. 57 kg)

Mass Breakdown (Stack) Total Mass = 118. 8 lb (54 kg)

Propulsion • Propulsion subsystem requirements • Schematic • VT thruster arrangement • System parameters • Operations summary

Propulsion Subsystem Requirements • Provide thrust required for the formation flying mission (phase 1) – 22 m/s DV required • Orbit raising to extend life (phase 2) – Remaining propellant • Augment torque coils for yaw attitude control

VT Thruster Arrangement Top View 1 2 3 4

Schematic Spring Ultem 2300 Thruster Assembly Teflon Fuel Bar Mica-paper / Foil Capacitor Ultem Isolator Cathode Boron Nitride Insulator Anode Thruster mount

System Parameters Power

Interfaces • Structural – 4 thruster nozzle holes, sized and placed as defined in drawings – 2 thruster mounts, attached directly to isogrid nodes • Power – – Requires 13 watts at 28 volts for translation System can tolerate a decrease in voltage to 16. 5 volts No power required when system not in use Approximate duty cycle: • 3% formation keeping • 10% formation maneuvering

Solar Cell • • • Tecstar Triple-Junction 24% Cascade cells Heritage on DS-1, Mighty. Sat, SMEX, TRACE, others Cell Dimensions: 2. 497” x 1. 522” (6. 25 x 3. 75 cm) 0. 030” spacing between cells Cells supplied kitted – Cover glass – Diode on each cell – Interconnects

Fabrication Composite structure comprised of 0. 23” isogrid and 0. 02” skin

Static Testing Strength & stiffness test of structure without skin panels Strength & stiffness test of loading fixture

Static Testing Strength & stiffness test of structure with skin panels • Experiment demonstrated a 32% gain in stiffness in the cantilever mode due to addition of skins • Skins added less than 8% to the total mass

Dynamic Testing Modal (tap) Testing of Side Panels • Hammer provides impulsive input • Accelerometer measures accelerations used to characterize natural frequencies • Tap testing with and without skins • Verification of predictions of finite element analysis

Up-Link Antenna Pictures

Clean Room Pictures

Acknowledgements • Air Force Research Laboratory • Air Force Office of Scientific Research • Defense Advanced Research Projects Agency • NASA Goddard Space Flight Center • NASA Wallops Flight Facility Test Center • University of Washington • Utah State University • Virginia Tech • Professor A. Wicks • Professor B. Love • Members of ION-F AFOSR Goddard Space Flight Center STP Defense Advanced Research Projects Agency