PACER Program
Preliminary Design Review Document
for the Aerospace Balloon Imaging Testing with Accelerometer (ABITA) Experiment
by:
Team The Interamerican Geospace Research Experiment (TIGRE)
Prepared by: H. B. Vo
Team Leader Date
A. M. Espinal Mena
Team Member Date
V. González Nadal
Team Member Date
J. Díaz Valerio
Team Member Date
Submitted:
Reviewed:
Revised:
Approved: ______
Institution Sign off (replace with name) Date
______
Institution Sign off (replace with name) Date
______
NSF PACER Sign off Date
Change Information Page
Title: PDR Document for ABITA Experiment
Date: mm/dd/yyyy
List of Affected PagesPage Number / Issue / Date
Status of TBDs
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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
3.3 Science Background and Requirements 3
3.4 Technical Background and Requirements 7
4.0 Payload Design
4.1 Principle of Operation
4.2 System Design
4.3 Electrical Design
4.4 Software Design
4.5 Thermal Design
4.6 Mechanical Design
5.0 Payload Development Plan
6.0 Payload Construction Plan
6.1 Hardware Fabrication and Testing
6.2 Integration Plan
6.3 Software Implementation and Verification
6.4 Flight Certification Testing
7.0 Mission Operations
7.1 Pre-Launch Requirements and Operations
7.2 Flight Requirements, Operations and Recovery
7.3 Data Acquisition and Analysis Plan
8.0 Project Management
8.1 Organization and Responsibilities
8.2 Configuration Management Plan
8.3 Interface Control
9.0 Master Schedule
9.1 Work Breakdown Structure (WBS)
9.2 Staffing Plan
9.3 Timeline and Milestones
10.0 Master Budget
10.1 Expenditure Plan
10.2 Material Acquisition Plan
11.0 Risk Management and Contingency
12.0 Glossary
LIST OF FIGURES
1. Figure on expected science results 3
2. Drawing of payload design 4
3. Block diagram of payload systems 4
4. Schematic of detector electronics 4
5. Schematics of power system 4
6. Flight software flow chart 4
7. Drawing of mechanical details 4
8. Flow chart of payload development 5
9. Flow chart of integration and testing 6
10. Diagram of flight profile 7
11. Flow chart of data processing and analysis 7
12. Project organization chart 8
13. Project time line diagram 9
LIST OF TABLES
1. Table of science and technical goals 3
2. Goals versus measurement traceability matrix 4
3. Power budget table 4
4. Weight budget table 4
5. Fabrication test list 6
6. Flight certification test list 6
7. Data rates and storage requirements 7
8. Interface List 8
9. Work breakdown structure 9
10. Project budget 10
11. Components and delivery times 10
12. List of risk items 11
1.0 Document Purpose
This document describes the preliminary design for the Aerospace Balloon Imaging and Testing with Accelerometers (ABITA) experiment by Team The Interamerican Geospace Research Experiments (TIGRE). It fulfills part of the NSF 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 A.B.I.T.A. 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, time line, work breakdown, expenditures and risk management is discussed. 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 TIGRE and the NSF PACER Institution Representative. Document change requests should be sent to team members and the NSF PACER Institution Representative.
2.0 Reference Documents
[1] Atmospheric Chemistry Data and Resources, S. Kempler, GDAAC Manager, http://www.oralchelation.com/clarks/data/p1.htm
[2] Aeronautics Internet Textbook: Wind, Copyright © 1996 by Cislunar Aerospace, Inc.
[3] Digital video camera from ACES 08 flight; provided by J. Giammanco, Louisiana State University Professor, Physics Department
[4] Lyndon State College: Department of Meteorology, Chapter 1: The Earth and its Atmosphere: Links of interest,
http://apollo.lsc.vsc.edu/classes/met130/notes/chapter1/vert_comp.html
3.0 Goals, Objectives, Requirements
3.1 Mission Goal
The mission is to determine balloon dynamics during flight, as it ascends bursts and descends, to help future development of platform stabilizing systems.
3.2 Objectives
The objective of this project is to have a better understanding of balloon dynamics during flight. To accomplish this main goal, the following parameters should be met:
3.2.1 Scientific Objectives
1. Obtain images of the environment surrounding the balloon platform
2. Compare acceleration vs. altitude to determine air mass movement
3. Determine rotational rate and translational movement of the payload.
4. Create a model of the balloon movement using cross-reference information collected from different instruments.
3.2.2 Technical Objectives
1. Include an imaging instrument capable of recording more than 4 hours.
2. Collect data from a three axis accelerometer from launch to landing
3. Collect data from a real time video source.
4. Collect data from a temperature sensor.
5. Project must be developed by a team of 4 persons and costs less than 500 dollars.
6. Entire payload must weight under 500g.
7. Complete PDR, CDR and FRR.
3.3 Science Background and Requirements
This section includes information gathered by research that provides a rationale for the mission as well as a context for our proposed measurements.
3.3.1 Science Background
The Earth’s atmosphere is divided in layers. Each layer of the atmosphere has its own characteristics. There are several conditions that occur in each of these layers, such as the presence of air, pressure and even forces acting through these layers. One of these layers is the stratosphere. The stratosphere is the second major strata of air in the atmosphere [1]. This region extends from 10 km up to 50 km. Here, the air temperature is fairly constant up to an altitude of 25 km. Then its temperature gradually increases up to 200-220 degrees Kelvin when reaching a height of about 50 kilometers. Since the air temperature in the stratosphere increases with altitude, it does not cause convection and has a stabilizing effect on atmospheric conditions in the layer. In this layer (the stratosphere) the ozone layer is present, which means that UV light rays are being absorbed by the ozone, thus causing a rise in temperature. This can either be more significant or less significant depending on the weather conditions, such as seasonal winds.
Figure 1 Temperature vs. Altitude by Grambling State University [3]
Figure 1 shows that as an object increases in altitude, the air temperature gradually decreases due to adiabatic expansion; yet, there is a point (at about 50,000 ft) in which the temperature remains the same before gradually increasing. The ozone layer extends approximately from 20km to 30 km (80000 ft-100000 ft) in the stratosphere; ozone absorbs UV radiation from the Sun, resulting in the heating of this region. Adiabatic expansion cools down then ozone layer and absorbs UV rays and heats the stratosphere up.
While traveling in the atmosphere, changes in temperature are due to the different characteristics of each atmospheric layer. That’s why many assume that turbulence will be present in an object traveling within an increasing altitude. Hot air rises from the equator as cold air replaces it, “falling” down. This happens because cold air is denser than hot air, causing gravity to pull it down while hot air “floats up”, as it is lighter than cold air. Wind is formed because of this and therefore so is turbulence. Hot air is heated up in the troposphere and cold air is coming down from stratosphere so as you change of altitude from one layer to another, turbulence experienced.
There are various instruments that will help measure these events. These instruments are devices for measuring acceleration and forces induced by gravity. Such devices can be of great help in understanding the movement of an object (such as aircraft) through different parts of the atmosphere. Video images from a previous ACE balloon flight revealed interesting turbulent events with increasing altitude. The balloon was exposed to different changes in temperature, pressure and wind throughout its flight. As the balloon was obtaining altitude, the temperate at which it was exposed was decreasing and its movements were circular and pendulum like.
During cloud free condition, the tilt angle of the balloon can be determined by comparing the change in horizon in time. A frame grabber type of software is used to obtain still images from the video. Tilt angle is defined to be positive if the horizon is seen to move upward. The rotational rate of the payload (counter clockwise is defined to be positive) is determined by study video images, about once every five seconds from approximately the start of the sixtieth minute (in reference to starting time of the video).
Time (minutes) MET / Altitude of the Payload (feet) / Tilt rate of change in Degree/second / Rotational Speed(revolution/second)
24 / 18000 / 14 / - 0.5
39 / 30000 / 12 / 1/4
47 / 45000 / 1 / -1/4
60 / 59000 / 15 / -1/4
107 / 105000 / 12 / 1 /7
118 / 52000 / 17 / 1/ 1
Table 1: Rotational and tilt rate of change
The table above shows the rate of tilt of the payload analyzed in the video. This represents the maximum inclination of the payload per second at that particular minute. This inclination was determined by observing the horizon and its position on the screen of the payload. The time was during that payloads flight.
3.3.2 Science Requirements
1. Need to record the time throughout the payload’s flight.
2. Need to be able to see the behavior of the payload’s surrounding environment.
3. Need to measure the temperature as function of altitude outside the balloon payload from launch until landing. The temperature will have to be measured in a range of -70° C to 30° C with 0.5° C.
4. Need the vector acceleration of the balloon payload during flight (.3% accuracy).
5. Need to know the rate of tilt and its relationship with the accelerometer. (1° accuracy).
3.4 Technical Background and Requirements
The principle of operation for the ABI TA experiment is its ability to collect data from different parameters that affect balloon flight. The experiment will in turn provide results that can be interlaced and give insight of the dynamics involved during the duration of flight.
3.4.1 Technical Background
The payload has enough instruments on board to reflect a good idea of its movement during flight. These components will have different measurements which then will be related to each other to then construct a model. Among the instruments on board are two temperature probes, an accelerometer and a video camera. The temperature sensor on board should be able to measure temperatures between 30° C and -70° C with a sensitivity of at least 0.5° C. Within this zone you encounter different temperature ranges and thus they have been plotted on previous experiments and have a predictable influence on balloon ascent rate. A known fact to many in the aviation industry is that there are certain areas in the air that currents of rising hot air will cause turbulence while flying through these. These events happen at lower altitudes than the tropopause so it does not involve the temperature change experienced in it. These events will determine another use for the temperature sensor which is to detect updrafts and down drafts (different rising and dropping rates in winds). This is the reason while the sensor should have a sensibility of .5° C so it reflects the small changes in these areas. The accelerometer “Z” axis reading will be used to determine an idea of the rising rate of the payload. This information can be cross-referenced to the independent GPS altitude data collected from the tracking beacons. The advantage of using an accelerometer is that it will provide multiple readings, as mentioned before it will output “Z” axis data but also it can output “X” and “Y” data. The corresponding data from these axes will provide insight of the rotational movement of the payload and its pitch level. This is where the video camera plays a role in the experiment. The information collected from the video will provide us with a visual idea of what the payload is going through. The camera will also assist in the analysis of the data because the audio feed for the camera will be used as an input from the accelerometer data. To accomplish this objective, the high frequency signal from the accelerometer needs to be conditioned so it becomes an audible tone free from as much noise as possible. With software like spectrograph the tone can be analyzed to determine which frequency response from the accelerometer corresponds to a certain position. The method that will be used to collect the data involves having the BalloonSat platform look at data for one minute and have it compare the readings. The reason for this is because the 8Kbyte EEMROM provides enough storage for this writing rate. In turn this will provide about 150 data points from launch to recovery. After the BalloonSat has looked through the information it will record the values extracted from the comparisons. The values that are of interests are the highest, lowest and average readings from the sensors for a time interval. Mainly this concept will be used for the accelerometer since the nature of the instrument is to give out continuous readings because of its sensitivity or bandwidth. The reason for this is that the while the platform is relatively calm it will not provide meaningful information thus if the record rate is high the instrument will record the same value over and over. This method guarantees that the data collected reflect the most important events in those one minutes of operation thus acting as a filter for unwanted data. The combination of rising rate, rotational rate and pitch level along with the actual video feed of the flight will provide an accurate representation of how the payload is actually behaving during flight.