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

Overview Introduction Mission & System Overview 3CS Mission ION-F Mission Design/Configuration Structure/Mass Propulsion Testing

Mission and System Overview Air Force Research Laboratory (AFRL) “TechSat-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 Emerald Orion 3-Corner Sat ION-F Nanosat-1 Nanosat-2

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 Mar01 Jun01 Sep01 Dec01 Mar02 04-06April 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, inter-satellite 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 University of Colorado at Boulder

3CS 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

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

ION-F Introduction/System 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

Multiple Satellite Deployment System Mission 3CS Configuration: ION-F USUSat Dawgstar The MSDS is under concurrent development with the university nanosatellites, and serves to supports the TechSat-21 Program. HokieSat Scenario: Multiple Satellite Deployment System

Separation Scenarios With current separation rate, we will be in constellation mode for 8 days, after that we are on individual mode

Multiple Satellite Deployment System (MSDS) 1. MSDS is released from SHELS 2. 96 hours later stacks separated from MSDS 3. 102 hours later satellites separated from each other. Nanosat-1 is an unpowered bus while it is mounted in the payload bay Differentiate between safety inhibits that prevent power from being available to to recontact hazards versus non-recontact hazards (i.e., T2 vs T1). Identify examples of recontact and non-recontact hazards Four day delay between Nanosat-1 ejection and Stack Ejection is provided in order to allow the shuttle to land, thus eliminating the potential for recontact. Recommended time between stack separation (T3) and intersatellite separation (T4) is approximately 1 hour

Leader / Follower Formation Orbit Ground Track

Same Ground Track Formation Orbit Ground Track

Design HokieSat 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 GPS Antenna Crosslink Antenna Solar Cells LightBand Pulsed Plasma Thrusters Data Port Camera Downlink Antenna Uplink Antenna Science Patches

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

VT Structures Overview

HokieSat Structure Panel 6 Panel 5 Panel 4 Nadir/Zenith Panel Panel 1

Hardware Description: Nadir and Zenith Heritage: None Ø0.190x3 Thru Description: Nadir and Zenith Heritage: None Manufacturer: In-House/Techsburg Properties: Al 6061 T-6, Class 3 Irridite (MIL-C-5541-E) Mass: 1.70 lbm (0.773 kg) Status: Prototype Complete

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

System Parameters Power

Interfaces Structural Power 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% for formation keeping 10% for formation maneuvering

Solar Cell Tecstar Triple-Junction 24% Cascade cells Heritage on DS-1, MightySat, 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

Modal (tap) Testing of Side Panels 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

Research Projects Agency 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