The frets1 satellite, presented at HPARC, aims to test a new ion engine design that utilizes electrostatic principles and pulsed plasma generation for increased thrust efficiency. It will operate in a polar sun-synchronous orbit and conduct a variety of experiments related to energy gathering, communication, and attitude control. The mission also incorporates amateur radio functionalities for telemetry and message relaying.

1. FRETS1 SATELLITE
Presented at HPARC, 2012-02-08

2. Agenda
 Mission
 Concept of Operations
 Technology
 Amateur Radio Tie-Ins

3. Mission - Goals
 Test a new ion engine design
 Electrostatic
principles
 Pulsed plasma generation
 Exhaust flow beyond classic Child-Langmuir limit
 Increased thrust per [kg, m3]
 (future) Alternative plasma generation method
 Lower power requirements
 (new) Alternative fuel storage
 Lower complexity for gas-based thrusters

4. Mission – TubeSat Standard
127mm
tall
500 grams + 250 grams payload
Images: Interorbital Systems

5. Mission – TubeSat Orbit
 310 km polar sun-synchronous orbit
 Decaying, 3-12 weeks
 90.7 minute orbit period
 Launch by
Interorbital Systems
interorbital.com
Image: Interorbital Systems

6. Mission - Thermal
 Average temperature, °C
PCB Material Metal Strips Hot Case Cold Case
Green PCB Aluminum, polished 95 -7
Green PCB Aluminum, anodized 68 -18
White PCB Polished copper 89 -7
White PCB Carbon black paint 84 1
White PCB Aluminum, polished 84 -19
White PCB 3M Black Velvet paint 83 1
White PCB Anodized black metal 81 -1
White PCB Gray paint 77 -6
White PCB Aluminum, anodized 57 -28

7. ConOps – Launch Operations
 Wait
 Launch
 Coast
 Release
 Wake
 Initialize

8. ConOps – Orbit Operations
 Safe
 Engine baseline experiments
 Engine effect experiments
 Sensor experiments
 Mechanical experiments
 Energy gathering
 Communication relay
 Status reporting

9. ConOps – End of Mission Ops
 Orbit decay
 Reentry

10. Technology - Communications
Main AX25
CPU Decoder MX614
BasicX 24 PIC Transceiver
433MHz band
100mW
AX25 Radiometrix
Encoder
PIC
Amplifier
500mW
Radiometrix

11. Technology – Comm. Board

12. Technology - Solar
 48 solar cells
8 strips of 6

13. Technology - Solar
Flat/Bullet Radial
0.75 Watt avg. 0.75 Watt avg.
on sun side on sun side
Sun Seeker
1.18 Watt avg.
on sun side

14. Technology - Power
Li-Ion
Battery
3.7V
Diodes 5200mAh
Step-Up
8 Current Voltage Deployment Comm.
Voltage
Sensors Regulator Switches Board
Converter
4.2V
5.7V
Engine
Board
8 Channel CPU
ADC Board
SPI

15. Technology - Microprocessor
 BasicX-24
 I2C interface
 IMU
 Flash memory
 SPI Solar ADC
Images: http://basicx.com/

16. Technology - Microprocessor
 SEU current sensor
 Shielding?
Image: http://www.aero.org/publications/crosslink/winter2000/03.html

17. Technology - Engine
 Electrostatic
 Child-Langmuir limit
to fuel flow
 Fuel flow limit
to Thrust density
 Use lasers to get
past classic limits
 Low thrust confuses
sensors

18. Technology - Fuel
 Nitrous oxide cylinder
 Lotsof fuel
 Not ConOps friendly
 Closed cell foam
 Easy storage – ConOps
 Semi-untested in space
 Pulsed Plasma Thruster
 Wide variety of fuel species
 Energy intensive Overview of PPT operation. (1) Energy
storage unit. (2) Ignitor. (3) Fuel rod.
(4) Plasma acceleration Credit: NASA
Images: http://www.lelandltd.com/mini_cartridges.htm
http://www.nasa.gov/centers/glenn/about/fs23grc.html

19. Technology – Attitude Sensing
 9 DOF
 HMC5883L magnetometer
 ADXL345 accelerometer
 ITG-3200 gyro
 I2C interface
 1.0 gram
 Manual correction for http://www.sparkfun.com/products/10183
drift and noise required.

20. Technology – Attitude Sensing
 9 DOF & Temperature
 Kalman filter
1.3 grams
45mA @ 5V
0.225 W
Open question:
Will Kalman filter out
our engine’s effects?
http://tech.yostengineering.com/3-space-sensor/product-family/embedded

21. Technology – Attitude Control
 Active Magnetorquer
 High Power
 High Price
Image: ISIS Magnetorqer, http://www.cubesatshop.com

22. Technology – Attitude Control
 Passive magnetic attitude control
 Permanent magnet
 Hysteresis rods
- Slow convergence
- Large fraction of payload space for rods
Images: http://www-personal.umich.edu/~mjregan/MCubed/Pages/O&C.html
http://cosmiac.ece.unm.edu

23. Technology – Attitude Control
 Piezoelectric Energy Harvesting
 Kinetic and spring energy to electrical energy
- New approach
- Dampens vibration
- Dampens rotational acceleration using lever arms
Images: http://piezo.com/prodproto4EHkit.html

24. Amateur Radio Tie-Ins
 Store and forward message(s)
 Compressed Sensing telemetry
 AX.25 Relays
 Other ideas?!

25. Wes Faler
wes.faler@gmail.com
Don Smith
FRETS1 Satellite
frets1.com