1. HokieSat Introduction
Daniel Pedraza Systems & Operations HokieSat 22 August, 2002

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

3. 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

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

5. 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

6. 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

7. 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

9. 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)

10. 3 CS Introduction/System
Three Corner Sat
Introduction/Systems
Arizona State University
New Mexico State University
University of Colorado at Boulder

11. 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

12. 3CS Mission Objectives Inter-satellite Communications
Virtual Formation Flying
Distributed & Automated Operations
Imaging
Modular, Generic Design
Micropropulsion Experiment
Student Education

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

14. 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

15. 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

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

17. Multiple Satellite Deployment System (MSDS)
1. MSDS is released from SHELS
2. 96 hours later stacks separated from MSDS
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

18. Leader / Follower Formation
Orbit
Ground Track

19. Same Ground Track Formation
Orbit
Ground Track

20. 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

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

22. 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)

23. VT Structures Overview

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

25. 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: lbm (0.773 kg)
Status: Prototype Complete

26. Mass
Total Mass = 16.6 lbm (7.57 kg)

27. Mass Breakdown (Stack)
Total Mass = lb (54 kg)

28. Propulsion Propulsion subsystem requirements Schematic
VT thruster arrangement
System parameters
Operations summary

29. 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

30. VT Thruster Arrangement
Top View 1 2 3 4

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

32. System Parameters
Power

33. 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

34. 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

35. Fabrication
Composite structure comprised of 0.23” isogrid and 0.02” skin

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

37. 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

38. 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

39. Up-Link Antenna Pictures

40. Clean Room Pictures

41. 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