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PACER Program
Preliminary Design Review Document
for the
Experiment
HumTemP
by
Team
SPARTA (Space Proximity
Atmospheric Research above Tropospheric Altitudes)
Prepared by:
Team Spokesperson (Dr. Wendy Hinton)
Date
Team Member (Jerod Baker)
Date
Team Member (Lisa Caraway)
Date
Team Member (James Mathis)
Date
Institution Signoff (replace with name)
Date
Institution Signoff (replace with name)
Date
PACER Signoff
Date
Submitted:
Reviewed:
Revised:
Approved:
Team SPARTA
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Change Information Page
Title: PDR Document for HumTemP Experiment
Date: 06/30/2008
List of Affected Pages
Page Number Issue
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Date
ii
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Status of TBDs
TBD
Section
Description
Date
Date
Created Resolved
Number
1
2
3.4.1
4.41
3
7.1.1
4
5
6
7.3.2
10.1
1.1
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Absolute humidity calculation
Amount of data space for the relative
humidity sensor
Amount of Salt solution need for
calibration
Error Analysis
Expenditure Plan
Material Acquisition Plan
iii
6/29/08
6/29/08
6/29/08
6/29/08
6/29/08
6/29/08
PDR v1.0
TABLE OF CONTENTS
Cover .................................................................................................................................... i
Change Information Page ................................................................................................... ii
Status of TBDs ................................................................................................................... iii
Table of Contents ............................................................................................................... iv
List of Figures .................................................................................................................... vi
List of Tables .................................................................................................................... vii
1.0
Document Purpose .................................................................................................. 1
1.1.
Document Scope ................................................................................................. 1
1.2.
Change Control and Update Procedures ............................................................. 1
2.0
Reference Documents ............................................................................................. 1
3.0
Goals, Objectives, Requirements ............................................................................ 2
3.1.
Mission Goal ....................................................................................................... 2
3.2.
Objectives ........................................................................................................... 2
3.2.1.
Science Objectives ...................................................................................... 2
3.3.
Technical Background and Requirements .......................................................... 2
3.3.1.
Technical Objectives ................................................................................... 2
3.4.
Science Background and Requirements.............................................................. 3
3.4.1.
Science Background.................................................................................... 3
3.4.2.
Science Requirements ................................................................................. 5
3.4.3.
Technical Background ................................................................................ 6
3.4.4.
Technical Requirements.............................................................................. 6
4.0
Payload Design ....................................................................................................... 7
4.1.
Principle of Operation ......................................................................................... 8
4.2.
System Design .................................................................................................... 8
4.2.1.
Functional Components .............................................................................. 9
4.2.2.
Component Interfaces ................................................................................. 9
4.2.3.
Traceability ............................................................................................... 10
4.3.
Electrical Design ............................................................................................... 11
4.3.1.
Sensors ...................................................................................................... 12
4.3.2.
Sensor Interfacing ..................................................................................... 12
4.3.3.
Control Electronics ................................................................................... 12
4.3.4.
Power Supply ............................................................................................ 13
4.3.5.
Power Budget ............................................................................................ 13
4.4.
Software Design ................................................................................................ 14
4.4.1.
Data Format and Storage .......................................................................... 14
4.4.2.
Flight Software.......................................................................................... 15
4.5.
Thermal Design ................................................................................................. 18
4.6.
Mechanical Design............................................................................................ 19
4.6.1.
External Structure ..................................................................................... 19
4.6.2.
Internal Structure ...................................................................................... 19
4.6.3.
Weight Budget .......................................................................................... 20
5.0
Payload Development Plan ................................................................................... 20
6.0
Payload Construction Plan .................................................................................... 20
6.1.
Hardware Fabrication and Testing .................................................................... 20
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6.2.
Integration Plan ................................................................................................. 21
6.3.
Software Implementation and Verification ....................................................... 21
6.4.
Flight Certification Testing ............................................................................... 22
7.0
Mission Operation ................................................................................................. 22
7.1.
Pre-Launch Requirements and Operations ....................................................... 22
7.1.1.
Calibrations ............................................................................................... 22
7.1.2.
Pre-Launch Checklist ................................................................................ 23
7.2.
Flight Requirements, Operations and Recovery ............................................... 23
7.3.
Data Acquisition and Analysis Plan ................................................................. 24
7.3.1.
Ground Software ....................................................................................... 24
7.3.2.
Data Analysis Plan .................................................................................... 24
8.0
Project Management ............................................................................................. 25
8.1.
Organization and Responsibilities .................................................................... 25
8.2.
Configuration Management Plan ...................................................................... 25
8.3.
Interface Control ............................................................................................... 25
9.0
Master Schedule .................................................................................................... 25
9.1.
Work Breakdown Structure (WBS) .................................................................. 25
9.2.
Staffing Plan...................................................................................................... 27
9.3.
Timeline and Milestones ................................................................................... 28
10.0 Master Budget ....................................................................................................... 31
10.1.
Expenditure Plan ........................................................................................... 31
10.2.
Material Acquisition Plan ............................................................................. 31
11.0 Risk Management and Contingency ..................................................................... 31
12.0 Glossary ................................................................................................................ 33
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LIST OF FIGURES
Figure 3-1 Temperature profile with increasing altitude ................................................... 4
Figure 3-2: Temperature and relative humidity as a function altitude............................... 5
Figure 4-1 Payload Design Diagram.................................................................................. 7
Figure 4-2 System Design Diagram .................................................................................... 8
Figure 4-3 Electrical System Design ............................................................................... 11
Figure 4-4 Sensor and control electronics ....................................................................... 12
Figure 4-5 Power Supply Design ...................................................................................... 13
Figure 4-6 Pre flight flowchart ........................................................................................ 16
Figure 4-7 In flight flowchart .......................................................................................... 17
Figure 4-8 Post flight flowchart ....................................................................................... 18
Figure 7-1 Ground software data retrieval design ........................................................... 24
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LIST OF TABLES
Table 1 Traceability Matrix ............................................................................................. 10
Table 2 Power Budget ...................................................................................................... 13
Table 3 Sampling Rates and Formats .............................................................................. 14
Table 4 Weight Budget .................................................................................................... 20
Table 5 Responsibilities ................................................................................................... 25
Table 6 SPARTA Staffing ............................................................................................... 27
Table 7 General Timeline ................................................................................................ 28
Table 8 Electrical System Timeline ................................................................................. 28
Table 9 Software System Timeline ................................................................................... 29
Table 10 Payload System Timeline .................................................................................. 29
Table 11 System Testing Timeline ................................................................................... 30
Table 12 Material Acquisition ......................................................................................... 31
Table 13 Risk Management ............................................................................................. 31
Table 14 Risk Severity Matrix ......................................................................................... 33
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1.0
Document Purpose
This document describes the preliminary design for the humidity measurement
experiment by Team SPARTA for the PACER Program. It fulfills part of the PACER
Project requirements for the Preliminary Design Review (PDR) to be held June 30, 2008.
1.1. Document Scope
This PDR document specifies the scientific purpose and requirements for the Humidity
Measurement experiment and provides a guideline for the development, operation and
cost of this payload under the PACER Project. The document includes details of the
payload design, fabrication, integration, testing, flight operation, and data analysis. In
addition, project management, timelines, work breakdown, expenditures and risk
management is discussed. Finally, the designs and plans presented here are preliminary
and will be finalized at the time of the Critical Design Review (CDR).
1.2. Change Control and Update Procedures
Changes to this PDR document shall only be made after approval by designated
representatives from Team SPARTA and the PACER Institution Representative.
Document change requests should be sent to Team members and the PACER Institution
Representative and the PACER Project.
2.0
Reference Documents
"Atmospheric Sounding." University of Wyoming College of Engineering. 20 June 2008
<http://weather.uwyo.edu/upperair/sounding.hmtl>.
Shipman, James T., Jerry D. Wilson, and Aaron W. Todd. An Introduction to Physical
Science. 12th ed. Boston: Houghton Mifflin Company, 2007. 535-566.
Deuber, Beat, Alexander Haefele, Dietrich G. Feist, Lorenz Martin, Niklaus Kampfer,
Gerald E. Nedoluha, Vladimir Yushkov, Sergey Khaykin, Rigel Kivi, and Holger Vomel.
"Middle Atmospheric Water Vapour Radiometer (MIAWARA): Validation and First
Results of the LAPBIAT Upper Tropospheric Lower Stratospheric Water Vapour
Validation Project (LAUTLOS-WAVVAP) Campaign." Journal of Geophysical Research
110 (2005).
Teets, Edward H. A Laboratory Study on the Phase Transition for Polar Stratospheric
Cloud Particles. National Aeronautics and Space Administration. Edwards, California:
NASA Dryden Flight Research Center, 1997.
NASA/Goddard Space Flight Center. "Satellite Finds Warming 'Relative' To Humidity."
ScienceDaily 16 March 2004. 29 June 2008 <http://www.sciencedaily.com
/releases/2004/03/040316073820.htm>.
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NASA/Goddard Space Flight Center--EOS Project Science Office. "Wetter Upper
Atmosphere May Delay Global Ozone Recovery." ScienceDaily 18 April 2001. 29 June
2008 <http://www.sciencedaily.com /releases/2001/04/010418072442.htm>.
National Center For Atmospheric Research. "New Space-Borne Instrument To Track
Greenhouse Gases, Ozone Destroyers, And Other Pollutants." ScienceDaily 8 July 2004.
29 June 2008 <http://www.sciencedaily.com /releases/2004/07/040708004132.htm>.
3.0
Goals, Objectives, Requirements
3.1. Mission Goal
Our goal for this experiment is to better understand the complex characteristics of the
atmosphere by investigating humidity, temperature and pressure within the troposphere,
tropopause and lower stratosphere.
3.2. Objectives
3.2.1. Science Objectives





Determine the relationship between pressure, humidity, and temperature within
the troposphere, tropopause and stratosphere as a function of altitude.
Compare the decrease of temperature with the change in pressure as altitude
increases.
Compare the data we obtained with data obtained from previous experiments by
NOAA which collects data points every minute.
Measure the increase in relative humidity above the tropopause.
Calculate absolute humidity from measurements.
3.3. Technical Background and Requirements
3.3.1. Technical Objectives






Launch a 0.5 kg payload 30km above the earth’s surface within the constraints of
the budget and weight requirements.
Construct a payload that will survive the extreme conditions of the tropopause
layer of the atmosphere.
Sensors will record data once every minute for one second.
Recover reliable measurements of humidity, temperature, and pressure in a near
vacuum environment for the duration of the flight.
Data recorded on electronics are recoverable after descent and landing.
Compare data recorded during flight to data taken by NOAA
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3.4. Science Background and Requirements
3.4.1. Science Background
What is the atmosphere? For earth, the atmosphere is a region surrounding the planet that
is commonly referred to as air. This air is a mixture of 78% nitrogen, 21% oxygen, .9%
argon, and .03% carbon dioxide: oxygen (O2) and nitrogen (N2) in the form of diatomic
molecules. While there is no distinct boundary between the earth’s atmosphere and
space, the atmosphere gradually thins with an increasing altitude due to gravity. Rather,
the atmospheric pressure decreases as a function of altitude. Atmospheric pressure is the
force applied to an object by the weight of the atmospheric gases above it, usually
expressed in inches Hg (mercury) or millibars. Within this gaseous region are layers:
troposphere, stratosphere, mesosphere, and the thermosphere with thin buffer regions in
between each layer seen in figure 3-1. The troposphere begins at the earth’s surface or
sea level to generally 16km above. The denser air of the troposphere contains 80% of the
atmospheric mass. It is in this layer that temperatures decreasing to as low as a -70 oC as
a function of increasing altitudes at a rate of 6.5 oC/km. The troposphere is also the
region where varying ranges in temperature and humidity can be observed as weather,
changing atmospheric conditions. Temperature is the measure of the average kinetic
energy of a system’s particles. Humidity is the water vapor content in the air. Often
humidity is reported as relative humidity and given in a percentage. Relative humidity is
the ratio of actual vapor pressure to saturation vapor pressure (the maximum moisture
capacity of the air) However, absolute humidity, what we intend to calculate, is the
amount of water present in a unit volume of air, expressed in a mass per volume unit
(kg/m³).
Above the troposphere, extending to 50km is the stratosphere. Ninety-nine percent of the
atmospheric mass is found in the troposphere and stratosphere. Unlike the troposphere,
the temperature increases with altitude, however, non-uniformly. The increase of
temperature in the stratosphere is due to the ozone layer: a blanket of Oxygen (O3)
molecules. The ozone layer filters most of the energetic short waves, ultraviolet light,
from the sun, giving off heat causing the rise in temperature of the stratosphere. In the
next layer, the mesosphere temperature decreases rather uniformly, reaching temperatures
as low as -90o C. This is the coldest region of the atmosphere. The mesosphere begins
nearly 50km high stretching to 80km in altitude. Right above the mesosphere is the
thermosphere it is heated by the sun up to temperatures reaching 1000 o C.
Atmospheric ballooning research has shown that small traces of water vapor can be found
above the altitude where water will freeze, in ascent. This is the essence of our
investigation. We intend to launch a balloon payload that will record humidity levels,
temperature and pressure levels, in order to answer questions about the increase in
humidity. Water vapor, one of the greenhouse gasses is important to further understand
global warming. Solar radiation of the sun passes through the atmosphere then absorbed
by the surface of the earth causing a warming effect. This energy is then emitted back
out as infrared radiation. While a small percentage of this radiation escapes into space
most is trapped in by the greenhouse gases, such as water vapor. Under ideal conditions
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a balance of incoming and releasing heat back out into space keeps the earth’s climate in
the steady state. When this rise in temperature persists over a period of time it is called
global warming. The presence of humidity in the upper atmosphere would suggest an
increase in greenhouse gasses namely water vapor. There have been many experiments
conducted in an effort to understand the existence of water vapor, therefore humidity, in
the upper atmosphere. The National Oceanic and Atmospheric Administration (NOAA)
have launching two sounding balloons a day at sites around the US for some years now.
One of the reasons for experiments is to observe whether these greenhouses gases are
increasing, the rate of increase, and which of the greenhouse gases are contributing. The
data we will discuss was retrieved from sounding balloons launched from Ft. Worth,
Texas during the summer of 2007. Figure 3-2 illustrates temperature and humidity as a
function of increasing altitude. In the first 20km, the troposphere, there is a decrease in
temperature. As well, there is a decrease in relative humidity with some variations due to
the dynamic nature of weather. From 20 km to about 40km, the stratosphere, temperature
increases while humidity continues to decline, but not to zero. This data indicates the
presence of small amounts of water vapor present in a region of the atmosphere that is
below freezing. We will be launching our payload in the summer from Palestine, Texas.
Therefore, we expect our data to be comparable to the data collected from NOAA’s
sounding balloons in the summer.
Figure 3-1 Temperature profile with increasing altitude
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Figure 3-2: Temperature and relative humidity as a function altitude
3.4.2. Science Requirements
In order to successfully conduct this experiment, and based on some data we have
obtained, we need to:
 Focus relative humidity measurements on the upper troposphere through
the lower stratosphere.
 Compare our flight data to NOAA’s flight data to aid in the investigation
of the troposphere, tropopause and stratosphere.
 Collect at least 230 data points containing humidity readings as low as 0%
for accuracy until the payload reaches 35,000m.
 Measure temperature, humidity, and pressure while ascending and
descending through and above the tropopause every 304.80m (1000ft.).
 Measure pressures as low as 5 mBars to gain accurate data.
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3.4.3. Technical Background
Our payload is going to measure the temperature outside of the payload, as well
as the relative humidity, and the atmospheric pressure. The pressure will be taken by a
sensor placed on the BalloonSat prototyping area, while we will have a sensor that is
taking temperature as well as a sensor detecting relative humidity outside of the payload.
These sensors will need to interface with the BalloonSat and save the data into the
EEPROM. The sensors will be powered by a separate 12V power supply to give them
enough voltage to operate.
Upon retrieval of the payload we will be calculate the absolute humidity from the data we
recorded during flight. The exact formula that will be used to calculate the Absolute
humidity is TBD.
3.4.4. Technical Requirements








Obtain one humidity data point every minutes for the duration of the flight
Ensure that any pressure, temperature, or humidity sensor will function at -80°C.
(The temperature it may encounter at the Tropopause)
The sensors must be able to interface with the BalloonSat
There must be enough voltage being supplied by the power source to keep the
BalloonSat for at least 3 hours (This will be the approximate duration of the flight
from ascension to descent).
The payload must be able to withstand shock experienced with landing at a speed
of approximately 19 km/hr.
The power supply must be able to continue functioning at extreme temperatures.
Inside of payload must be maintained at a temperature above -20 degrees Celsius.
In order to guarantee accurate functionality of the circuits within the parameters
specified by their respective data sheets
Sensors must accurately record the external temperature and humidity.
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4.0
Payload Design
Our experiment will be housed within a hollowed out Styrofoam will measure
approximately 20cm x 15cm x 8cm. It will include additional Styrofoam within it to
provide a form of insulation. There will small openings in the hull in which the
temperature and humidity sensors will be inserted in order for them to obtain accurate
readings of the external conditions. There will be two vertical holes that will be lined
with straws on opposite sides of the payload diagonal from each other, which will allow
the payload to be attached to the balloon without the strings rubbing against the
Styrofoam wearing down its design integrity.
Incorporated within the payload will be several components. There will be the
BalloonSat which will serve as our control unit and the place where our sensors will be
connected. There will also be our power supply and insulation included inside of the box.
Figure 4-1 Payload Design Diagram
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4.1. Principle of Operation
The payload will contain a temperature sensor, humidity sensor, and a pressure sensor.
The payload will be reaching an altitude of approximately 30 km rising at a speed of
approximately .3km every minute. We will be taking temperature, humidity, and pressure
readings once every minute for the duration of the flight (ascension as well as descent).
Each set of data will be saved as a byte of the 8kb EEPROM and given a serial number.
Once the balloon is recovered the information will be taken from the BalloonSat and put
into graphical format using Microsoft Excel in order to present. With the data we have
recorded we will calculate the absolute humidity for each point and display it as a graph.
4.2. System Design
Figure 4-2 System Design Diagram
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4.2.1. Functional Components
There are six key components in our payload. The most important of these components is
the BalloonSat. This functions as our control unit. Our programs are written into the
BASIC Stamp and they begin to send out specific commands to all of the sensors. Our
power supplies are two Lithium batteries. One is a 9V battery which powers the
BalloonSat while the other is a 12V battery that powers the Sensors. Each of our three
sensors has their own functions which they must carry out but are all are vital for our
goals. The temperature sensor measures the temperature outside of the payload. Our
humidity sensor functions in the same way in the respect that it is also outside of the
payload taking measurements. Our pressure sensor will be inside of the payload however.
With all of this data there must be a place to store it. Our data archive system will be the
EEPROM of the BalloonSat
4.2.2. Component Interfaces
Every aspect of the payload interfaces with one another. The actual structure of the
payload has a bi-directional thermal and mechanical interface. There is a power interface
that runs from the batteries to the BalloonSat and the various sensors being used. There
will be an analog Data Interface going from the sensors to BalloonSat's ADC. There is a
bi-directional digital data signal between the Control Sub-system (BalloonSat) and the
Digital archive sub-system (EEPROM). There is a bi-directional digital signal from the
Control system and the ground interface system. There is a bi-directional digital signal
between the analysis and ground interface subsystem.
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4.2.3. Traceability
Table 1 Traceability Matrix
Mission Goal:
Our goal for this experiment is to better understand the complex characteristics of the atmosphere by investigating humidity, temperature and
pressure within the troposphere, tropopause and lower stratosphere.
objectives
Requirements
Design Element
Determine the relationship between
pressure, humidity, and temperatures
a function of altitude.
Payload survive extreme temperature
and pressure conditions of the
trapopause
Compare the data we obtained with
data obtained from previous
experiments by NOAA which
collects data points every minute.
Calculate absolute humidity from
measurements.
Ensure that the
temperature and humidity
sensor function -80oC
Inner temp. -20 external
temp -70
Sensors are placed outside the
payload container
Sensors will record data
once every minute for one
second
Software sampling and
recording rate of 1 data point
per minute
Measure temperature,
humidity, and pressure
while ascending and
descending through and
above the tropopause
every 304.80m (1000ft.).
Enough voltage supplied
by the power source to
keep the BalloonSat for at
least 3 hours
Include Relative Humidity
sensor
Launch a 0.5 kg payload
30km above the earth’s
surface within the
constraints of the budget
and weight requirements
Use Styrofoam for payload
construction
Measure temperature, humidity, and
pressure while ascending and
descending through and above the
tropopause every 304.80m (1000ft.).
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Use Styrofoam and yellow
monocot covering
Power Budget (TBD)
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Implementation
External payload dimensions of 16 cmx6
cm x10.5 cm
Equation to calculate absolute humidity
given pressure, temperature and relative
humidity
4.3. Electrical Design
Figure 4-3 Electrical System Design
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4.3.1. Sensors
4.3.2. Sensor Interfacing
Figure 4-4 Sensor and control electronics
4.3.3. Control Electronics
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4.3.4. Power Supply
In the lab a power supply will be used for testing the BalloonSat. During flight the
voltage will be supplied by two lithium batteries referred to in Figure 4-5.
Figure 4-5 Power Supply Design
4.3.5. Power Budget
The max current needed for the BalloonSat is 161mA for 3 hours. A 9V battery has a
capacity of 1200mAh and can support the BallooSat for up about 7hours.
The max current needed for sensors is 660mA for 3hrs. A 9V and 3V battery connected
in series has a capacity of 1820. (9V refers to above data and the 3V supplies a 620mA up
to about 2.75 hours).Voltage regulators will be used to reduce voltage for individual
units.
Table 2 Power Budget
Power
Source 1
Operational
Voltage
(V)
Team SPARTA
Current
(min – max)
(I)
13
Hours to
Function
(H)
Total Min
Current drain
(I*H)
Total
Max
Current
drain
(I*H)
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BalloonSAT
Power
Source 2
Pressure
Sensor
(Approx)
Humidity
Sensor
(Approx)
Temperature
Sensor
(Approx)
5V
53.7mA
3
-
161mA
7V - 9V
75mA 100mA
3
225mA
300mA
7V – 9V
50mA - 60mA
3
150mA
180mA
7V - 9V
50mA –
60mA
3
150mA
180mA
4.4. Software Design
4.4.1. Data Format and Storage





Outside Temperature Sensor- 1 byte
o Data will be acquired at:
 1 point /min
Humidity Sensor- 1 byte (Official- TBD)
o Data will be acquired at:
 1 point /min
Pressure Sensor- 1 byte
o Data will be acquired at:
 1 pt. /min
Time Stamp- 3 bytes
o Hr- 2 nibbles
o Min- 2 nibbles
o Sec- 2 nibbles
Entire Flight Memory Usage – 1.08 KB (Official- TBD)
o 6 bytes/ min. x 180 min. x 1 sec
Table 3 Sampling Rates and Formats
Byte
1
2
3
4
Team SPARTA
Data Stored
Format
Sampling Rate
Hours
Minutes
Seconds
Temperature
00-24
00-59
00-59
TBD
N/A
N/A
N/A
1 pt./ min
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5 Pressure
6 RH
TBD
0-255
1 pt./ min
1 pt./ min
4.4.2. Flight Software
PRE-FLIGHT
Figure 4-6 represents the preflight software which is designed to first prompt the user to
initialize the clock. The user will input date and time information to start the real time
clock. The program will then prompt the user for the actual pressure, temperature, and
humidity, and initialize their variables. Next the EEPROM address will be initialized to
zero, so that when the program starts writing data to memory, it begins writing to the first
address of the EEPROM. Next, some test data, such as “FF”, is initialized. It is then
written to every address in the memory. Subroutines will be implemented to ensure that
the program will stop writing when the memory is full. The program will then read back
the data inputted into the memory. If the data read back matches the data inputted, the
clock time is read back. Likewise, if the clock time is correct, the program will proceed,
otherwise it will terminate with a message to the user about which test was failed. Next,
the sensors’ readings will be recorded as data, via the ADC to EEPROM. Next, the
memory will be read back. Next, the program will check to see if the data read back
matches the data in reality. If the data matches, the memory will be reinitialized to a
value such as “FF”.
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Figure 4-6 Pre flight flowchart
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IN-FLIGHT
Figure 4-7 represents the in flight software for the HuTemP experiment. The
first thing that will be done in the flight software is the initialization of the EEPROM
address to zero. The memory has already been initialized beforehand. Next, we read data
back from the sensors by sending the analog signal to the ADC, then to the EEPROM.
Memory space is then checked to make sure there is sufficient room for an entire set of
data—time stamp, pressure, humidity, and temperature. If there is enough, the address is
checked for available free space in memory. This is to ensure that if the program restarts,
for any reason, the program will not overwrite any previously collected data. If the
address is free, the data is written into the address and a time stamp is stored. If not, the
address is incremented to check the next address’ availability. The process repeats until
either the batteries are disconnected or the memory is full.
Figure 4-7 In flight flowchart
POST-FLIGHT
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Figure 4-8 The data recovery program will initialize the address of the EEPROM
to the first address—zero. Next, the data read from the sensors will be read back from the
EEPROM. Following it, the corresponding time stamp will be read back from memory.
Next, the program will output the time stamp to the display screen along with the data.
Figure 4-8 Post flight flowchart
4.5. Thermal Design
Our Payload will be going into an environment where the temperature can reach low
temperatures exceeding -60 degrees Celsius. The temperature at which the circuits,
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however, can operate at a range that will record fairly reliable data is -20 degrees Celsius.
The survival range for these parts only goes down to -40 degrees Celsius. With these
factors in mind you can begin to imagine the challenge that we will be faced with in order
to keep these instruments warm in an environment that far exceeds their survivability
range.
To counteract these disadvantages we are faced with we have come up with several
solutions. The container that these components are being contained in is used for
insulation in homes. This will help to aid in keeping the equipment warm. We will also
be using a Lithium 9V battery as well as a 12V battery. When they are in use they
generate heat as well as the circuitry they are powering. All of these factors should keep
the inside our payload above the -20 degree limit of the circuitry.
4.6. Mechanical Design
A Styrofoam cube box will be the design for the container of our payload. It will be made
from Dow Styrofoam which is rigid in form and lightweight. It weighs approximately .2
grams per square inch. This is beneficial when dealing with our weight budget that will
be examined in a later section. Our payload will be able to the different forms of stress it
may encounter during the duration of the flight.
4.6.1. External Structure
The payload will look like a cube from the outside. The dimensions will be
approximately 16cm x 6cm x 10.5cm. There will be two holes in the exterior of the
container to allow for the temperature and humidity sensors to make accurate readings in
the atmosphere. There will also be two holes running vertically at two corners of the
container lined with straws to allow the payload to be attached to the strings coming from
the balloon. To access the interior of the container there is a removable lid that is secured
down with tape.
4.6.2. Internal Structure
Once you open the lid you will then be looking at the interior of our payload that will
house our power system, control system, data archive systems, etc. Within one of the
walls of our payload a small notch will be cut into the Styrofoam to house our
BalloonSat. The batteries will be on the side of the BalloonSat held in place by
Styrofoam which will serve the dual purpose of keeping them warm and securing them
from moving around during flight and landing
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4.6.3. Weight Budget
A Styrofoam cube box will be the design for the container of our payload. It will be made
from Dow Styrofoam which is rigid in form and lightweight. It weighs approximately .2
grams per square inch of 1.5cm thick foam. This is beneficial when dealing with our
weight budget that will be examined in a later section. Our payload will be able to the
different forms of stress it may encounter during the duration of the flight.
Table 4 Weight Budget
Items
Box/Insulation
Circuits
Power & Cables
Weight (g)
100
120
110
Uncertainty (g)
±10
±15
±25
330
±50
Total
5.0
Payload Development Plan
In order to take our experiment from the PDR to CDR there are some important
steps we must first take. We have to first decide upon what sensors we will be using in
our experiment. This is of particular importance because it tells us important information
such as how much power we will require, how much memory we will need, etc. We will
then need to prototype our box to see if the dimensions are sufficient and it is structurally
sound to be dropped. We will also need to prototype our circuits on a solderless
breadboard to test if they work before integrating them onto the BalloonSat.
6.0
Payload Construction Plan
6.1. Hardware Fabrication and Testing
We will begin our fabrication by placing an order for the necessary parts. Upon reception
of the necessary parts we will break off into our separate areas of expertise. Our
electronics person will create the circuits we need on a solderless breadboard to
determine what needs to be done to create a functioning circuit without destroying the
BalloonSat. Once this has been done they will be placed onto the BalloonSat and
soldered into place. While this process is being done the Mechanical person will be
constructing the container for the payload. Part availability is an important thing to keep
in mind during the fabrication process. If important parts have not yet arrived it will slow
down the development phase which will put us in a bit of a time crunch. For parts that
may take a long time to arrive we must make sure we get the order in early.
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6.2. Integration Plan
Our payload contains six subsystems in total: power, data archive, control, mechanical,
thermal, and sensors. In order to properly integrate these components, the mechanical
subsystem must first be implemented by constructing a 3-D, Styrofoam box that will
physically interface with the outside environment. The thermal subsystem will be
implemented through the implementation of the mechanical subsystem, which is a
thermal insulator. By retaining any heat generated by the BalloonSat or other
components, the thermal subsystem will protect the BalloonSat from the extremely low
temperatures it will face, both in testing and in flight. The pressure sensor will be
physically integrated onto the BalloonSat. While the temperature and humidity sensors
are still TBD, the data archive subsystem, or the EEPROM, is already integrated in the
control subsystem. The power subsystem will physically be connected to the control and
sensor subsystems and will consist of one 9V battery and one 12V battery. The sensors
will be physically integrated to the control subsystem. To ensure the integrity of the
control, thermal, and sensor subsystems, particularly during flight, tests will be conducted
in extreme cold and low-pressure environments in an attempt to collect write and read
back accurate data. These tests will also help to determine the integrity of circuits and
solder joints—the mechanical subsystem.
6.3. Software Implementation and Verification
In order to implement the flight program, the Basic Stamp Editor programming language
will be used. A main loop is needed in order to continuously record data and time stamps.
To read data from the sensors, a subroutine for reading from the ADC will have to be
implemented, as well as a subroutine for writing the data to the EEPROM; the clock time
will also be written to the EEPROM via this subroutine. “IF THEN/ELSE” statements
will have to be created in order to perform the ‘memory space’ and ‘free address’ checks.
Until the memory is full, program will proceed through the previous functions. In order to
be certain that the software runs properly, we will run all three programs (pre-flight, inflight, and post-flight). We will place the BalloonSat, while running the flight software,
in conditions similar to what it will face in the troposphere, tropopause and lower
stratosphere. If the flight program runs and produces legitimate data, it will be approved
for flight.
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6.4. Flight Certification Testing
There are many conditions we may face as we travel into higher altitude. There will be a
decrease in pressure, temperature, as well as a considerable amount of shock caused by
turbulence and landing. These can have catastrophic effects on data gathering if not
properly accounted for and tested during payload design. In order to test if the payload
will survive and function in the cold of the upper atmosphere we must test it. We can do
this by placing it in a container that will be surrounded by dry ice. This will give us an
idea of the payload’s functionality on an environment similar to the temperature
experienced by the Tropopause. In order to simulate how the payload will function in a
low pressure environment like the upper atmosphere we must test it by placing it in a
vacuum. This will allow us to know if it will be able to function even at low pressure.
The payload must also survive the turbulence and shock of landing. To simulate this we
can shake the payload some and drop it from a height of approximately ten feet and see
how it handles the fall.
7.0
Mission Operation
7.1. Pre-Launch Requirements and Operations
Before launch there are several events need to take place. First, software must be
carefully inspected for bugs, and programs must be run proper data storage and recovery.
All sensors must be properly calibrated and tested for functionality. To properly calibrate
the sensors, equations will need to be determined from graphing the data retrieved by
testing the software functionality. The software to test the data storage and recovery will
also be used to start the Real Time Clock. The memory must then be initialized to some
value that can never appear as data, for instance “FF”, to prevent overwriting real data.
Before launch, the flight software must be implemented and run. Finally, the payload
must then be physically attached to the balloon.
7.1.1. Calibrations
In order to properly analyze the data we will retrieve, we need to calibrate three particular
sensors, temperature, relative humidity, and pressure, as quickly as possible. To calibrate
the temperature, we will take measurements at three different temperatures: 0 degrees
Celsius, 20 degrees Celsius, and 85 degrees Celsius. We will calculate the ADC count at
each using an equation (TBD).
For the pressure sensor, we will use similar procedures, only using a vacuum
chamber to create pressures at 1000 mBars (slightly less than 1 atm), 500 mBars, 200
mBars, and 10 mBars. We will then use an equation for pressure (TBD) to calibrate the
sensor.
As for the humidity sensor, we will need small samples (exact TBD) of salts:
LiCl, NaCl, MgCl, and K2 (SO4). We will need to create saltwater solutions for each of
the different salts. We will then place a lid over the glass container, containing the
solutions. After a half-hour, for each, we will place the relative humidity sensor within
2cm of the solution. Each of these salt samples, when saturated with water, produces a
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different measurement of relative humidity of some percentage. Allowing our constant
will be the temperature of the water, we will use these different percentages in an
equation for absolute humidity (TBD) to calibrate the relative humidity sensor.
7.1.2. Pre-Launch Checklist
24-hrs before launch
 Run Pre flight Program
 Set real-time clock
 Run In flight Program
 Attach payload to Balloon
Day of launch
 Install new batteries
 Secure BalloonSat, sensors, and batteries to payload
 Secure Payload shut with tape
7.2. Flight Requirements, Operations and Recovery
During flight, the flight software will be running on the payload, which will gather data.
During the tracking, altitude and position will need to be monitored for proper data
analysis and payload recovery to occur. The highest altitude to which the payload will
ascend is close to 35,000 meters, the pressure will decrease to as low as 4 mBars, and the
temperature will drop close to -70°C. The ascension rate is approximately 1000 ft. per
min. The batteries will need to provide sufficient power to the payload throughout the
entirety of the flight in order to collect the data.
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7.3. Data Acquisition and Analysis Plan
Figure 7-1 Ground software data retrieval design
7.3.1. Ground Software
In order to properly retrieve the data that was collected by the flight software, the postflight software will need to initialize the EEPROM’s address to zero and read back the
raw data from the memory. Figure 7-1 shows the sequence for the retrieval of the raw
data in Basic Stamp Editor. The Basic Stamp Editor programming language must be used
to run the post-flight software. The program Term 232 will be used to interface the data,
received from the EEPROM, from Basic Stamp Editor to Microsoft Excel.
7.3.2. Data Analysis Plan
Equations (TBD) will be used to converting the raw data to physical quantities using
Excel. This converted data will then be placed into Excel tables and graphs for final data
analysis. Error analysis will also be performed on our data. We will plot temperature,
pressure, relative humidity, and absolute humidity as a function of altitude. Our pressure,
relative humidity and temperature data will then be compared to NOAA’s data.
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8.0
Project Management
8.1. Organization and Responsibilities
Table 5 Responsibilities
Responsibilities
Team leader/Management
Mechanical Design
Software Design
Electronic Design
Team Member
Dr. Hinton
Jerod Baker
JP Mathis
Lisa Caraway
Email
[email protected]
[email protected]
[email protected]
[email protected]
8.2. Configuration Management Plan
When changes in mechanical, software or electronic design are need, they will be
conveyed to the team members during the team meetings. The change will be properly
documented in the team notebook and in the corresponding document.
8.3. Interface Control
Interface control will be done through the notebook located in room 321 Nicholson Hall
and the daily meetings. All changes to the software system, electrical system and
payload system will be communicated at the meetings and documented in the notebook.
9.0
Master Schedule
The following section will give a general overview of the scheduling for Team SPARTA.
The work breakdown structure is show in section 9.1. Each team member was assigned a
design area according to various strengths. The various milestones (PDR, CDR and
FRR) are listed in section 9.3. More work is needed on the project scheduling to make
sure that each task able to be complete on time.
9.1. Work Breakdown Structure (WBS)
1.0 Electrical System
1.1. Decide on type sensor
1.1.1. Temperature
1.1.2. Humidity
1.1.3. Pressure
1.2. Schematic drawing
1.2.1. BalloonSat
1.2.2. New Interface board
1.2.2.1.Sensor interface design
1.3. Power Supply
1.4. Circuit Prototype
1.5. Fabrication of Circuit Board
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PDR v1.0
2.0 Software System
2.1. Basic Stamp
2.1.1. Pre flight
2.1.1.1. Flowchart developed
2.1.1.2. Software developed
2.1.1.3. Testing
2.1.2. In flight
2.1.2.1. Flowchart developed
2.1.2.2. Software developed
2.1.2.3. Testing
2.1.3. Post flight
2.1.3.1. Flowchart developed
2.1.3.2. Software developed
2.1.3.3. Testing
2.2. PC
2.2.1. Data Retrieval and Storage
2.2.2. Conversions ADC counts to physics quantity
2.2.2.1. Temperature
2.2.2.2. Humidity
2.2.2.3. Pressure
2.2.3. Calculation Absolute Humidity
2.2.4. Graphical representation
2.2.4.1.Temperature vs. Altitude
2.2.4.2.Pressure vs. Altitude
2.2.4.3.Relative Humidity vs. Altitude
2.2.4.4.Absolute Humidity vs. Altitude
2.2.5. Comparison with NOAA data
3.0 Payload System
3.1. Schematic drawing
3.1.1. Frame construction
3.1.2. Sensor attachment
3.1.3. Balloon attachment
3.2. Thermal Interface
3.2.1. Design
3.2.2. Construction
3.3. Fabrication of frame
4.0 Testing
4.1. Circuit Board Testing
4.2. Senor testing
4.3. Thermal Testing
4.4. Vacuum Testing
4.5. Shock Testing
5.0 Documentation
5.1. Preliminary Design Review
5.1.1. Paper
5.1.2. Presentation
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PDR v1.0
5.2. Critical Design Review
5.2.1. Paper
5.2.2. Presentation
5.3. Flight Readiness Review
5.3.1. Paper
5.3.2. Presentation
6.0 Balloon Launch
7.0 Science Presentation
9.2. Staffing Plan
SPARTA staff
Table 6 SPARTA Staffing
J P Mathis - Software design, Documentation
Lisa Caraway- Electrical design, , Documentation and Equipment acquisition
Jerod Baker – Payload Design, Circuit Board Fabrication, Testing
Documentation, and Equipment acquisition
Dr. W. Hinton – Management and Documentation
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PDR v1.0
9.3. Timeline and Milestones
Milestones for this experiment include successfully completion of the PDR due June 30th, CDR due July 9th and the FRR due July 25th.
Once these milestones are met the launch and recovery of the experimental payload will be the final milestone for this experiment.
Table 7 General Timeline
Table 8 Electrical System Timeline
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Table 9 Software System Timeline
Table 10 Payload System Timeline
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Table 11 System Testing Timeline
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10.0 Master Budget
10.1.
Expenditure Plan
TBD
10.2.
Material Acquisition Plan
TBD
Table 12 Material Acquisition
Item
Acquisition
Batteries
Purchase
Sensors
Existing
Temperature
Cost
Lead time
(IM457temp sensor diode)
Existing
Pressure
(IC 1210 015A psi)
Humidity
Purchase
Existing
Existing
Styrofoam
BalloonSat
11.0 Risk Management and Contingency
Table 13 Risk Management
Risk
Contingency Plan
Likely
hood
Impact
Personnel
Responsible
2
5
Jerod
2
1
Jerod
2
4
Jerod
Testing of all electric
components
Testing of all electric
components
3
5
Jerod
3
3
Jerod
Test electrical components
after receipt
2
2
Jerod
Work in a “clean” environment
5
3
Lisa
Bread board prototype circuit
3
3
Jerod
Mechanical
Payload falls apart
mid flight
Payload dropped
preflight
Payload broken after
fabrication but before
flight
Document the shock test results
to ensure structural integrity
Document the shock test results
to ensure structural integrity
Handle carefully
Electrical
Component fails
during flight
Component fails
before flight (before
testing)
Component fails
before flight (after
testing)
Drop sensitive
component during
fabrication
BalloonSat destroyed
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(magic smoke)
Bad Solder joint
during fabrication
Not installing battery
for launch
4
4
Jerod/ Lisa
3
5
Lisa
3
5
JP
2
4
Jerod/ Lisa
2
4
Jerod/ Lisa
Check order before sent
Transferring Risk
2
3
4
5
Lisa
Develop weight budget with
3
5
Jerod
Develop equipment budget
with 20% contingency
Daily meetings and hardcopy
of system work placed in
notebook
1
5
Jerod
5
4
Team
Joints inspected by second
person and the circuit testing to
assure working circuit board
Designate battery installer
Software
Forget to take
computer/program to
Palestine, TX
Make a check list before
packing to leave for Palestine,
TX
Thermal
Sensor freeze
during flight
Circuit board freeze
during flight
Document results of thermal
testing to ensure that sensor
will function within
temperature range
Document results of thermal
testing to ensure that sensor
will function within
temperature range
General
Wrong sensor order
Payload not
recovered
Exceed weight
budget
Exceed financial
budget
Undocumented
change
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Table 14 Risk Severity Matrix
Drop sensitive
component
during
fabrication
5
Bad Solder joint
during
fabrication
4
BalloonSat
destroyed
Component
fails before
testing
Likely
3
2
Undocumented
change
Payload
dropped
preflight
Component
fails before
flight (after
testing)
Sensor freeze
or
Circuit board
freeze during
flight
Payload broken
after fabrication
but before flight
Wrong sensor
order
Exceed weight
budget
Not installing new
battery for launch
Forget to take
computer/program
to Palestine, TX
Payload not
recovered
Payload falls apart
mid flight
Exceed financial
budget
1
1
2
3
4
5
Impact
12.0 Glossary
PACER
CDR
FRR
PDR
TBD
TBS
WBS
RH
NOAA
Physics and Aerospace Catalyst Experiences in Research
Critical Design Review
Flight Readiness Review
Preliminary Design Review
To be determined
To be supplied
Work breakdown structure
Relative Humidity
National Oceanic and Atmospheric Administration
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