Small Satellite Technology

Small Satellite Technology

An proof of concept senior design project
Sponsors	NASA Jet Propulsion Labratory Kamal Oudrhiri NASA Idaho Space Grant Consortium David Atkinson
Team Name	Pantheon
Duration	Fall 2013 - Spring 2014
Faculty Advisers	Touraj Assefi Amrit Dahal
Mentors	David Eld Jason Bjur

Small Satellite Weather Balloon Technology Design Project

Project Goal

To demonstrate a proof of concept for a radio science technique to measure the dynamics of a planetary atmosphere using a capsule in flight. [pantheondesignproject.wordpress.com]

Project Background

An important measurement in the study of planetary atmospheres is the profile of wind speeds from the upper atmosphere to the surface. Entry and descent probe measurements of the winds of Venus, Jupiter, and Saturn’s largest moon Titan have been made by Doppler tracking of Pioneer and Venera probes, the Galileo probe, and the Huygens probe, respectively. The winds in the upper atmosphere of Venus were also measured by tracking the Soviet VEGA balloons. The most significant shortcoming to these measurements is that they provide one profile of winds at a single location. The dynamics of planetary atmospheres can be better characterized if the winds are measured simultaneously at multiple locations. One concept for doing this is to have a single ground station such as a planetary lander that would release multiple balloon-borne transceivers that continuously transmit to the ground station. By making precise frequency measurements at the ground station of the signal from each balloon capsule in flight, the Doppler shift of the signal can be used to provide an accurate measurement of the balloon dynamics and from this the wind dynamics can be inferred.

Project Goals

Electrical Requirements

Design, build, test communications system for measuring frequency at sampling rate TBD
- 433 MHz
Use a tape measure for a transmitting antenna
Select three receiver antennas to consider
- Must be directional
Provide end to end test of communications system

Mechanical Requirements

Mass (FAA)
- Less than 2.72 kg
Dimensions (CubeSat standard as defined by Cal Poly)
- Cube 10 x 10 x 10 cm, known as 1U
Temperature (VAST data collection)
- Internal requirements
  - No less than 0 °C and no greater than 40 °C
    - Goal: 0°C - 10°C
- External minimum reaches -50 °C

Project Learning

Mechanical Engineering

Cube Material

Initial Cube Material Research

Structural Material Specifications	Material Roles	Insulation Material Specifications	Material Analysis
Meets P104 Standards High Quality High Strength at Low Temperatures Low Weight Weather Resistant Low Cost	File:2014 Pantheon Material structure.jpg	Flexible & Durable High Resistivity & Thermal Range Weather Tight Electronic Capabilities Lightweight support for a stronger material	File:2014 Pantheon Material insulation.jpg Insulation Material

Final Cube Material:

From the initial design review of material we chose DOW "Utilityfit" Insulation, but after researching the DOW website, we found DOW TUFF-R insulation to be the best option for the mass design parameters specified below:

Federal Aviation Administration mass requirement
- Entire system - structural and communications/electrical - can be no more than 2.72 kg
Current mass
- Total: 0.5 kg
  - Includes: carbon fiber walls, aluminium blocks, insulation

Heat Transfer

The Heat Transfer Goals are to finalize an insulation thickness for the cube that will keep the electronics at their operating temperature in a worse case scenario.

Preliminary EES Solution

Required Specifications:

Minimum Inside Cube Temperature of -15°F
Altitude Dependent Values

Assumptions:

Carbon Fiber Structure Negligible
DOW Utilityfit Insulation
Generated Heat is removed by convection to the surroundings and radiation by the box
Altitude of 80,000ft

Solution:

Insulation Thickness
Total Power Loss

Finalized EES Solution

The finalized solution adds radiative heat transfer as well as validates the prior exclusion of carbon fiber convective heat transfer in the code.

Required Specifications:

Minimum internal temperature at 0 °C
- Must maintain operational temperature TBD of transmitter hardware
VAST data suggests minimum external temperature of -50 °C

Assumptions:

DOW TUFF-R Insulation
Generated Heat is removed by convection to the surroundings and radiation by the box
Altitude of 80,000ft

Solution:

Insulation Thickness
Total Power Loss
Carbon Fiber Wall Convective Heat Transfer 0.056% difference
- Negligible due to wall thickness

Electrical Engineering

Electrical device selection is based on a worst case scenario model. The component requirements are as follows:

Transmitter Requirements:

420-450 MHz
Transmit minimum of 53 miles Line of Sight (LOS)
- For 80,000 feet altitude and 60 mile horizontal distance

Board Requirements:

Type of oscillator
- Silicon or Crystal
High clock speed

Flight Elements

Initial Flight Elements:

Transmitter Options:

Transmitter 1	Transmitter 2
Specifications 432-434 MHz With 6.5” antenna Omnidirectional 7 grams 75 mile LOS -30F to +120F 1.2” X 0.5”X 0.5” Includes battery	Specifcations 432-434 MHz With 6” antenna Omnidirectional 4.5 grams 50 mile Line of Sight (LOS) 1” X 0.38”X 0.25” Includes battery

Board Options:

Circuit Board	Specification
	Board 1 100 MHz fixed oscillator Up to 400 MHz clock generator
	Board 2 100 MHz Silicon Oscillator Has ability to integrate Crystal Oscillator into the circuit (IC6/7 socket)

Crystal Oscillator

Crystal Oscillator Selection:

Specifications:

SG-8002JF-PCC (Digikey)
1 MHz-125 MHz
Can be used with Spartan 3E TQ144 and CP132
3.3 V (max)
28 mA (max)
-20C ~ +70C
7.1mm X 4.6mm X 1.5mm

Interim Flight Elements

Other internal flight elements were added to allow for proof of concept design to progress to a future cubesat design.

CANSAT Kit Rev 2
- Pressure sensor
- Temperature sensor (not included)
  - TMP37 Analog Devices
- One additional peripheral port - use of which is TBD
- Transmitter
  - Meets AX.25 protocol
  - Transmits at 433.92 MHz
  - 5 g
- Power
  - 9 V provides 5 hours of operation
  - Up to 5 V transmit power
- Arduino compatible microcontroller

Ground Element

Yagi antenna
- CANSAT Receiver
- Directional

Antennas

Flight Antenna (Transmitting)
- 433 MHz quarter-wave dipole
  - 17.3 cm length

Wind Measurements

GPS
- VAST system
Doppler shift
- Use communications system to accurately measure doppler shift
- Use doppler shift to calculate satellite LOS speed
Third method: external sensor
- Currently researching

Project Development

Mechanical Engineering

Cube Design

SolidWorks Cube Model:

Following CubeSat standard
- 10 x 10 x 10 cm, known as 1U
Carbon Fiber Panels with Pumpkin CubeSat inspired cutouts
- Cutouts to adhere to hardware requirements
Threaded Aluminum blocks for cube panel connections
Milled Insulation to hold desired electronic operating temperature

Current Cube Structure Prototype:

A rapid prototyping machine was used to construct the initial prototype and basal wood cubes stood in place of the aluminum blocks. The insulation was not included.

Structure uses six 0.96 x 0.96 cm carbon fiber squares
- 4 mm difference accounts for two 2 mm thick carbon fiber panels
- May need to account for screw heads by countersinking or further reducing panel dimensions

Manufacturing

Tooling Plate:

The Tooling Plate is used for cutting out the carbon fiber panels. The tooling plate is mounted in our Haas CNC mill, the mill is zeroed to the tooling plate using reamed hole in top left corner. Carbon fiber blanks are mounted to the tooling plate and cut out using the mill.

Cube Corners:

The Cube Corners are threaded to join all eight corners of the cube, made using SHARP manual mill.

Electrical Engineering

Link Budget Assumptions

Best Case	Worst Case	Both Case
Transmit antenna gain: 1 dB Receiving antenna gain: 7 dB Receiving line loss: 0 dB Receiving antenna pointing loss: 0 dB Receiving antenna polarization loss: 0 dB	Transmit antenna gain: 0 dB Receiving antenna gain: 3 dB Receiving line loss: -2 dB Receiving antenna pointing loss: -2 dB Receiving antenna polarization loss: -2 dB	Transmit waveguide loss: 0 db Transmit antenna pointing loss: 0 dB Distance: 22.36 km Frequency: 433 MHz

Link Budget Results

Free space loss: -112.17 dB
EIRP:
- Best: 27.99 dBm
- Worst: 26.99 dBm
Receiving antenna effective aperture:
- Best: 0.1911 m^2
- Worst: 0.07611 m^2
Received power:
- Best: -77.18 dBm/-107.18 dBw
- Worst: -88.18 dBm/-118.18 dBw

Selected Transceiver

BHX2-433-5-SMA

Radiometrix product
Frequency: 433 MHz
Transmit power: 500 mW
Receiver sensitivity: -118 dBm

Antennas

Transmitting antenna

17.3 cm quarter-wave dipole antenna

Ground station/Receiving antenna

430 MHz yagi antenna

Preliminary Compliance Matrix

Mechanical

Design Parameter	Requirement	Requirement Source	Design/Analysis Method	Calculated Values
Mass	Less than 2.7 kg	FAA	Solidworks 3D Modeling/Prototype	0.185 kg - Current Prototype Mass (sans electronics)
Thermal	Internal Temp. 0°C-10°C	Electronics Data Sheet	EES Heat Transfer Model/Cold Chamber Testing	0°C - EES Heat Transfer Model TBD - Cold Chamber Testing
Dimensions	1U - 10x10x10cm	Cal Poly CubeSat Standard	Solidworks 3D Modeling/Prototype	Solidworks - 10x10x10cm Prototype - 10x10x10cm

Electrical

Design Parameter	Requirement	Requirement Source	Current Design
Transmit Antenna	Linearly polarized, low gain	Project Description	Dipole/Monopole
Receive Antenna	Directional	Project Description	Yagi
Data Acquisition	2 Methods of Wind Speed Measurement	Project Description	GPS (VAST balloon), Doppler
Transmission Frequency	220-225 MHz 420-450 MHz	FCC frequency allocation	433.92 MHz
Dimensions	<1000 cm^3	Cal Poly CubeSat Requirements	355 cm^3

Testing

Structural	Communications
Simulation drop test To ensure the structure can sustain impact upon release 1.52 meter drop test To ensure the structure can sustain impact as well as protect and keep the internal hardware stable Cold Chamber Test Verify ability to hold internal temperature above minimum electronic hardware operating point Ambient pressure External temperature -40 °C (minimum temperature the chamber is able to reach) Length of test is 2 hours (VAST cut down time for capsules) No electronics will be operating inside External and internal temperatures will be recorded	Establish link Show that system transmits and receives Doppler Show that doppler shift accurately calculates wind speed Sensor Investigate third method for measuring windspeeds

Cold Chamber Test

Purpose: To obtain a relative range for the temperature drop inside & outside of the cube, for verification that the insulation system can maintain an electrical operating temperature between 0°C and 10°C.

Results: Graph the Temperature Drops vs. Time

Outside of cube to Inside of cube
Inside of cube @ start and end of test
Chamber @ start and end of test

Cold Chamber Tests

Temperature Validation Test	Decreasing Temperature Test (Idealized Flight) 1hr 30min	Constant Temperature Test (Worst Case Scenario) 30min	Increasing Temperature Test (Extended Landing) 1hr
Purpose: validate test setup through data acquisition	Starting Cold Chamber Temperature: -15°C ≤ Tstart ≤ 15°C Ultimate Cold Chamber Temperature : Tend ≤ -58°C	Relatively constant Cold Chamber Temperature: Tmin ≤ -58°C	Starting Cold Chamber Temperature: Tstart ≤ -58°C Ultimate Cold Chamber Temperature : 0°C ≤ Tend ≤ 15°C

Results

Temperature Validation Test:

Completed Feb. 13th & Feb. 14th

Cold Chamber Decreasing Temperature Range

15°C to -58°C
Minimum Temperature reached within 1hr

Cube Design Analysis Steady State Heat Transfer Code

Includes Heat generation
- 9 Volt Batteries
- Handwarmers

Insulation Top Closure

Air tight

Drop Test

Purpose: To verify that the external structure can withstand landing impact stresses and analyze design problems from fracture points.

1.5m Drop
Kibbie Dome Parachute Drop

Results: Visual Assessment (VAST) Graph - Accelerometer Data of Impact (Tensegrity Group)

Antenna Chamber Test

Antenna chamber at Gonzaga University, 3 meters in length, will be used to conduct the tests on both transceivers.

3D radiation pattern
Verify link budget
Transmit power
Receiver sensitivity
EIRP

Will perform the radiation pattern, transmit power, receiver sensitivity, and EIRP test at room temperature then again with the transceivers cooled to 10°C.

Project Risks

Thermal overheating or freezing of electronics
Limited cold chamber testing time
Further reducing structure size to compensate for screw heads and wall thickness to meet CubeSat standard limits internal space for communications system
Cube fabrication may delay drop testing
Spring launch dependent on weather
Time to acquire components - shipping, back order
System power
Transmission distance

Project Timeline

November

Finalize communications hardware

December

Order most components
Verify communication link
Finalize structure
December 6 Snapshot 2
December 20 complete prototype

January

January 23 Begin structure testing

February

February 10 Complete all testing
Start compiling paper

March

Mid-March 2014 flight date
Evaluate for areas of improvement

April

April 25 Finalize paper

May

May 2, 2014 Engineering Expo

Pantheon Team

Team Members	Biographies
	My name is Aaron Kitchen. I am originally from Seattle, Washington. I am pursuing a degree in Mechanical Engineering with a minor in material science and writing. My experience in 3D modeling allowed me to receive two summer internships at The Boeing Company, where I worked as a manufacturing engineer for the Wind Tunnel and Flight Test programs. In my spare time I enjoy writing and baking. I look forward to returning to work for Boeing after I graduate in May 2014.
	My name is Philip George Petersen. I am from Idaho Falls, Idaho and love all outside activities, mountain biking in particular. I thought this was what I was going to do with my Mechanical Engineering Degree. I have also studied German since high school and just finished my minor last semester. These two passions culminated in an internship with NICOLAI bikes in Lübbrechsten, Germany. I have found there and my other internship at Idaho National Laboratory (INL) that I love new challenges involving cutting edge technology, I saw both of these in this JPL project. I am excited for what challenges this project will pose and hopefully we will deliver a satisfying result.
	My name is Jessica Slater. I am from Lind, Washington. I am majoring in Electrical Engineering. For the past four summers I have interned with the U.S. Government in Washington D.C. which allowed for experience in testing and research. Outside of school I enjoy read and cooking.
	My name is Stephen Wayne. I am originally from Idaho Falls, Idaho. I am pursuing a degree in Electrical Engineering with a minor in business, and expect to graduate in May, 2015. I have interned at Schweitzer Engineering Laboratories in Reliability Engineering, and will be returning to NASA’s Jet Propulsion Laboratory in Radio Science Engineering for Summer 2014. I am interested in electromagnetics, robotics, and emerging technologies.
	Rhys grew up in Idaho Falls and graduated from Hillcrest High School in 2009. He shared his father’s interest in electronics and computing which lead to his undergraduate studies at the University of Idaho. Mr. Perry will acquire his B.S. in Computer Engineering in December of 2013. In his free time, Rhys enjoys mountain biking, video games, and collecting LEGO sets.