Introduction
Three years ago, a group of students at Inspiring Minds attempted to design and build a high altitude weather balloon project. This group of students met once a week, and mapped out the entire project from start to finish. Sadly the team never did finish. They got caught up, and obsessed with finding a specific piece of hardware online. Instead of working around this inconvenience, they let the problem slow their momentum. They weren't able to finish by the time they graduated, so the project has been sitting in the basement of Inspiring Minds ever since. My mentor told me about this dormant project and I was interested right off the start. I thought this was right up my alley so I decided to bring the project back to life. Even though I am using this for my senior thesis project, this was originally an Inspiring Minds idea, so my mentor and I decided to put together a tech team of about five Inspiring Minds’ students that would help with the completion of this project. We turned the project into an after school program witch Inspiring Minds gladly funded. I meet with my tech team once a week, every Thursday afternoon to work on the project and to start planning the launch/ recovery.
Objective
The goal of this project is to design a payload system that is capable of operating in the extreme environmental conditions of near space. The payload will be designed to survive the entire journey to the edge of the atmosphere back down to the surface of the Earth for recovery, analysis, and hopefully re-flight for future tech teams. Since the payload can experience violent turbulence in the jet stream, we must design a lightweight, rugged payload capsule that can resist damage and ensure the safe return of the equipment used in the flight. The payload capsule will be designed to withstand both extremely hot and extremely cold temperatures, as well as protect its contents from cosmic radiation. During the ascent, the payload, using a light-weight camera, will be taking pictures of the curvature of the Earth, controlled by a micro timing circuit. These photos will be used to illustrate and document the entire ascent to the edge of the atmosphere back down to the surface, through a time lapse video. The lift will be provided by a 1200 gram weather balloon filled with helium. The balloon and the payload will be connected by a 5 ft rope that is capable of breaking at 50 lbs of impact force. The payload system will also have a 5 ft parachute rigged to the capsule for when the balloon pops, so the contents of the payload can return safely to Earth. I will be using a SPOT GPS transmitter along with an altitude sensor to track the balloons entire flight. If the GPS functions properly I will be able to recover the payload once it touches back down. The payload will also contain a GPS board (data logger) to save the GPS coordinates throughout the flight. Once I recover the payload I can convert the GPS and altitude data to an overlay for Google Earth, which would map out the entire trajectory of the flight. The payload will also have a temperature and pressure sensor that will record the change in temperature and pressure as the altitude increases. This data will be recovered after the flight and organized into a graph that will illustrate the change in temperature and pressure as you reach higher altitudes in the atmosphere.
Design Constraints
FAA/FCC Regulations
Through my research I found out that my project is in fact legal. I do not require a permit to launch my experiment, as long as my design falls under certain size and weight limits, as well as having a radar reflector to make the balloon visible to planes. In the United States there are sets of regulations governing launching and tracking high altitude weather balloons. The Federal Aviation Administration (FAA) dictates these regulations. Part 101 of the FAA Regulations covers balloons, kites, and rockets. The first section of Part 101 spells out exactly what kinds of devices the rest of Part 101 applies to. Regarding “Unmanned free Balloons” Part 101 applies if the balloon:
(i) Carries a payload package that weighs more than four pounds and has a weight/size ratio of more than three ounces per square inch on any surface of the package, determined by dividing the total weight in ounces by the area in square inches
(ii) Carries a payload package that weighs more than six pounds
(iii) Carries a payload, of two or more packages, that weigh more than 12 pounds
(iv) Uses a rope or other device for suspension of the payload that requires an impact force of more than 50 pounds to separate the suspended payload from the balloon
The FAA also prevents the use of cell phones to track high altitude weather balloons during flight. § 22.925 "Prohibition on airborne operation of cellular telephones. Cellular telephones installed in or carried aboard airplanes, balloons or any other type of aircraft must not be operated while such aircraft are airborne (not touching the ground). When any aircraft leaves the ground, all cellular telephones on board that aircraft must be turned off" ~www.ecfr.gov. I am also not permitted to launch a weather balloon anywhere near heavily populated areas, as well as airports or government facilities. This is mainly for the safety of others. Another requirement is that all unmanned weather balloons are required to have a radar reflector attached somewhere to either the balloon or the payload. FAA Regulation, Title 14, Part 101, Subsection D, Section 101.35 states: "No person may operate an unmanned free balloon unless...the balloon envelope is equipped with a radar reflective device...that will present an echo to surface radar operating in the 200 MHz to 2700 MHz frequency range". I must design my project around these restraints if I want to avoid any legal complications.
(i) Carries a payload package that weighs more than four pounds and has a weight/size ratio of more than three ounces per square inch on any surface of the package, determined by dividing the total weight in ounces by the area in square inches
(ii) Carries a payload package that weighs more than six pounds
(iii) Carries a payload, of two or more packages, that weigh more than 12 pounds
(iv) Uses a rope or other device for suspension of the payload that requires an impact force of more than 50 pounds to separate the suspended payload from the balloon
The FAA also prevents the use of cell phones to track high altitude weather balloons during flight. § 22.925 "Prohibition on airborne operation of cellular telephones. Cellular telephones installed in or carried aboard airplanes, balloons or any other type of aircraft must not be operated while such aircraft are airborne (not touching the ground). When any aircraft leaves the ground, all cellular telephones on board that aircraft must be turned off" ~www.ecfr.gov. I am also not permitted to launch a weather balloon anywhere near heavily populated areas, as well as airports or government facilities. This is mainly for the safety of others. Another requirement is that all unmanned weather balloons are required to have a radar reflector attached somewhere to either the balloon or the payload. FAA Regulation, Title 14, Part 101, Subsection D, Section 101.35 states: "No person may operate an unmanned free balloon unless...the balloon envelope is equipped with a radar reflective device...that will present an echo to surface radar operating in the 200 MHz to 2700 MHz frequency range". I must design my project around these restraints if I want to avoid any legal complications.
Weather Conditions
The atmosphere is composed of many layers, each of which provides different environments. My project must be designed to survive all of these different environments. The vertical structure of the atmosphere is mostly differentiated by temperature. A high altitude weather balloon traverses through the troposphere (the first layer) and flies up into the stratosphere (second layer). The temperature decreases in the troposphere as altitude increases. The Air at these higher altitudes is cooler because the pressure is lower. Gases, such as air expand at lower pressures. As a gas expands the atoms within it move more slowly. Since air temperature is a measure of how fast the atoms in the air are moving, the rate of motion, of atoms as well as the temperature are both lower at higher altitudes. The temperature does begin to level off during the transition into the stratosphere though. This transition is called the tropopause witch is located about 15-20km above Earth's surface. This difference in temperature rate is due to convection. In convection, energy is transferred by the movement of a heated fluid, such as air or water. In this case the air at the bottom of the troposphere is warmed by Earth's surface. The hot air is less dense than the cooler air above it, so it rises. The air cools as it rises until it reaches an equilibrium altitude at the tropopause. Once the weather balloon begins to ascend through the stratosphere the temperature begins to rise. This is because the atmosphere is heated from above by the absorption of ultra violet light by the ozone layer in the upper reaches of the stratosphere. A typical temperature profile from a high altitude balloon flight can range anywhere between -54 to 100 degrees Fahrenheit. Because of this I need to design a payload capsule that can protect its contents from these extreme temperatures. I also need to choose the most reliable electrical equipment that can function properly under such conditions as well.
Radiation has to be taken under consideration as well, when planning a high altitude weather balloon experiment. Radiation affects electronics and any other exposed technological equipment, as well as the cells of living beings. Here radiation means electromagnetic waves (photons), neutral (neutrons) and electrically charged energetic particles (electrons, protons, He ions, also called alpha particles, and ions of any other chemical elements, which are referred to as heavy ions). The composition of the atmosphere can be altered by interaction with this radiation. The flux of ionizing radiation increases as the weather balloon reaches higher altitudes. This radiation is known as cosmic rays. Most cosmic rays detected in Earth’s atmosphere are secondary particles. These secondary particles are created by the collision of a primary cosmic ray with an atom in Earth’s upper atmosphere. The secondary particles go on and strike other atmospheric atoms producing more cosmic rays. This whole process is called an atmospheric cascade. If the primary cosmic ray has enough energy (greater than 500 million electron volts) the nuclear byproducts of the cascade can reach Earth’s surface. “Over one million secondary particles pass right through your body every minute.” ~www.nscl.msu.edu. There are different types of direct damages that these energetic particles can do to electrical equipment. In single event effects (SEE) damage results from a single ionizing particle that traverses an electronic device. An impacting energetic particle can create an electron-hole pair that can disrupt the usual response of an electric circuit. Single event upsets (SEU) are produced especially by heavy ions of the primary cosmic rays or secondary particle generated in the atmosphere by a primary high-energy proton. They can generate faulty commands in on-board computers, and can cause latch-ups, an abnormal state of an electronic device where it can no longer respond to input signals. Worst cases of SEEs are burn outs, which means a permanent and irreversible circuit damage by parasitic current flows. Increased vulnerability is caused by the miniaturization of technologies, where single charges can deposit enough energy to cause SEE. The most well known and used operating model used to monitor secondary particles is the Cosmic Ray Effects on Micro-Electronics (CREME) model, developed by NASA, which is accessible through the Space Environment Information System (SPENVIS) interlink, developed by ESA. Both of these operating models are available online for free.
Radiation has to be taken under consideration as well, when planning a high altitude weather balloon experiment. Radiation affects electronics and any other exposed technological equipment, as well as the cells of living beings. Here radiation means electromagnetic waves (photons), neutral (neutrons) and electrically charged energetic particles (electrons, protons, He ions, also called alpha particles, and ions of any other chemical elements, which are referred to as heavy ions). The composition of the atmosphere can be altered by interaction with this radiation. The flux of ionizing radiation increases as the weather balloon reaches higher altitudes. This radiation is known as cosmic rays. Most cosmic rays detected in Earth’s atmosphere are secondary particles. These secondary particles are created by the collision of a primary cosmic ray with an atom in Earth’s upper atmosphere. The secondary particles go on and strike other atmospheric atoms producing more cosmic rays. This whole process is called an atmospheric cascade. If the primary cosmic ray has enough energy (greater than 500 million electron volts) the nuclear byproducts of the cascade can reach Earth’s surface. “Over one million secondary particles pass right through your body every minute.” ~www.nscl.msu.edu. There are different types of direct damages that these energetic particles can do to electrical equipment. In single event effects (SEE) damage results from a single ionizing particle that traverses an electronic device. An impacting energetic particle can create an electron-hole pair that can disrupt the usual response of an electric circuit. Single event upsets (SEU) are produced especially by heavy ions of the primary cosmic rays or secondary particle generated in the atmosphere by a primary high-energy proton. They can generate faulty commands in on-board computers, and can cause latch-ups, an abnormal state of an electronic device where it can no longer respond to input signals. Worst cases of SEEs are burn outs, which means a permanent and irreversible circuit damage by parasitic current flows. Increased vulnerability is caused by the miniaturization of technologies, where single charges can deposit enough energy to cause SEE. The most well known and used operating model used to monitor secondary particles is the Cosmic Ray Effects on Micro-Electronics (CREME) model, developed by NASA, which is accessible through the Space Environment Information System (SPENVIS) interlink, developed by ESA. Both of these operating models are available online for free.
Hardware
Payload Capsule Prototype
The first design involved using a Styrofoam cooler for the payload capsule. I felt that this design was not durable enough to survive the journey to near space. To determine if the capsule was durable enough I decided to kick the cooler down a flight of stairs with some of the components hooked up inside, to see how much damage it can absorb without damaging the equipment. I ran this test three times over with three different Styrofoam coolers. All three coolers failed miserably. One of the coolers did in fact survive the test but the size and weight would have limited our project to just a single camera and a GPS. I wanted to be able to accomplish more through this project so I had to start looking into other options. The results told me to find a more durable capsule that can protect the equipment from different weather conditions during the ascent , as well as survive the force of impact on the way back down. Finding the perfect capsule was going to be a challenge.
Payload capsule
Through my research I found a company website that designs and launches all sorts of high altitude weather balloon projects. The website is called www.sky-probe.com. The website has all sorts of equipment for high altitude weather balloon projects. Based on hundreds of flights they have put together a list of the most reliable, light weight, inexpensive equipment for designing your own project. This website is where I found the perfect payload capsule. This capsule is specifically designed to endure multiple journeys to the edge of the atmosphere, back down to the surface of the Earth. The capsule is pressure equalized and is close to being air tight, protecting its internal hardware from dust, water, and moisture. The sky probe box has pre-scored pull and pluck foam layers used to house your experiments. This foam keeps all the equipment in place and prevents things from moving around. It's internal dimensions are 7.9"L x 4.7"W x 4.0"D which is just enough room to house all of our equipment. The box is also extremely light weight, weighing only a total of 0.9lbs.
contour roam hd camera
This camera is designed for outdoor use, and can definitely take a beating. Through my research I found that this camera is the most reliable, light-weight, inexpensive camera on the market. It weighs only 5.1oz which is definitely a benefit when taking the 12 pound weight limit into consideration. This camera also has a 3 hour battery life which is more than enough time to capture images of the full ascent to the edge of the atmosphere.
-Photo Mode: Every 1, 3, 5, 10, 30, or 60 seconds
-5MP Sensor
-Codec - H.264/AAC / File Type - MOV
-AAC Audio Compression
-32GB microSD Compatible
-Photo Mode: Every 1, 3, 5, 10, 30, or 60 seconds
-5MP Sensor
-Codec - H.264/AAC / File Type - MOV
-AAC Audio Compression
-32GB microSD Compatible
spot gps
This device will be used to track the payload throughout the entire flight. The location is posted on the SPOT website once every 10 minutes. I found this to be the most reliable way to track the payload without using a HAM radio. SPOT uses it's own satellite network to send it's location directly to their website. The only thing is that SPOT, like other GPS devices only tracks under 60,000 ft. We will not be able to track the payload after that point until the balloon pops and falls back under 60,000 ft.
This device requires a $100 / year operating agreement and a $50 / year charge for real time tracking.
This device requires a $100 / year operating agreement and a $50 / year charge for real time tracking.
Radar Reflector
FAA Regulation, Title 14, Part 101, Subsection D, Section 101.35 states: "No person may operate an unmanned free balloon unless...the balloon envelope is equipped with a radar reflective device...that will present an echo to surface radar operating in the 200 MHz to 2700 MHz frequency range".
My project requires a radar reflector so it is visible to Air Traffic Control radars. This reflector allows my weather balloon to look like an airplane on other radars. This is to prevent my project from getting hit by an actual airplane.
My project requires a radar reflector so it is visible to Air Traffic Control radars. This reflector allows my weather balloon to look like an airplane on other radars. This is to prevent my project from getting hit by an actual airplane.
Arduino uno r3
An Arduino is basically a micro controller/ prototyping platform. It can be used to develop interactive objects, taking inputs from switches or sensors, and controlling lights, motors or other physical outputs. This is a very important tool for this project. I require an Arduino to tell my sensors when to turn on and off. I also need it to be able to pull the data off the sensors after the flight. An Arduino is capable of communicating with the sensors through a little programming. The codes to do so can be found online.
GPS DAta logger
This little GPS module is a very inexpensive way to get started in data logging GPS coordinates. This board requires an Arduino to pull the data off, after the flight though. Once the flight is done, the data can easily be converted to overlay on Google Earth, to show the exact trajectory of the balloon. The only thing is that it needs to have a microcontroller send the "Start Logging" command. However, after that message is sent, the microcontroller can go to sleep and does not need to wake up to talk to the GPS anymore to reduce power consumption. The time, date, longitude, latitude, and height is logged every 15 seconds and only when there is a fix. The internal FLASH can store about 16 hours of data as well.
Using an Arduino, connect VIN to +5V, GND to Ground, RX to digital 2 and TX to digital 3.
Using an Arduino, connect VIN to +5V, GND to Ground, RX to digital 2 and TX to digital 3.
BAROMETRIC PRESSURE/TEMPERATURE/ALTITUDE SENSOR
This precision sensor is the best low-cost sensing solution for measuring barometric pressure and temperature. Because pressure changes with altitude it can also be used as an altimeter. As we travel from below sea level to a high mountain, the air pressure decreases. That means that if we measure the pressure we can determine our altitude This sensor is perfect for what I originally wanted to do. With this little chip, I can now record both temperature, pressure, and altitude all on one small device. I have saved a lot of room, weight and money which is pretty important for this kind of project.
Using an Arduino, you simply connect the VIN pin to the 5V voltage pin, GND to ground, SCL to I2C Clock (Analog 5) and SDA to I2C Data (Analog 4).
Using an Arduino, you simply connect the VIN pin to the 5V voltage pin, GND to ground, SCL to I2C Clock (Analog 5) and SDA to I2C Data (Analog 4).
Rope " Strength Test"
FAA states that:
§101.1 Applicability.
(a) This part prescribes rules governing the operation in the United States, of the following:
(4) Except as provided for in §101.7, any unmanned free balloon[1] that --
(iv) Uses a rope or other device for suspension of the payload that requires an impact force of more than 50 pounds to separate the suspended payload from the balloon is prohibited.
I had to test the strength of our balloon teather in order to get permission from the FAA to launch the project. According to the FAA the rope we use to connect the weather balloon to the payload capsule must be capable of breaking under 50 lbs of applied force. This requirment is in place to protect passengers aboard commercial airplanes in the event of an accidental collision with an unmanned weather balloon. The rope strength must be able to break under 50lbs of force so that the rope would cause no damage if sucked into one of the planes turbines.
I started asking around and looking into effective ways to test rope strength. A proffessor at Brown University told me about Brown's engineering department and mentioned that they had a machine that is used to test rope strength. The professor connected me to the right person and I arranged a field trip to the engineering department for my afterschool program. We tested eight different ropes before finding the perfect one. It was deffinitely a cool experience and I was really surprised at how strong some of the ropes were.
§101.1 Applicability.
(a) This part prescribes rules governing the operation in the United States, of the following:
(4) Except as provided for in §101.7, any unmanned free balloon[1] that --
(iv) Uses a rope or other device for suspension of the payload that requires an impact force of more than 50 pounds to separate the suspended payload from the balloon is prohibited.
I had to test the strength of our balloon teather in order to get permission from the FAA to launch the project. According to the FAA the rope we use to connect the weather balloon to the payload capsule must be capable of breaking under 50 lbs of applied force. This requirment is in place to protect passengers aboard commercial airplanes in the event of an accidental collision with an unmanned weather balloon. The rope strength must be able to break under 50lbs of force so that the rope would cause no damage if sucked into one of the planes turbines.
I started asking around and looking into effective ways to test rope strength. A proffessor at Brown University told me about Brown's engineering department and mentioned that they had a machine that is used to test rope strength. The professor connected me to the right person and I arranged a field trip to the engineering department for my afterschool program. We tested eight different ropes before finding the perfect one. It was deffinitely a cool experience and I was really surprised at how strong some of the ropes were.
Contacting the FAA
I knew contacting the FAA was going to be difficult from the start. While researching high altitude weather balloon flights, during the planning stages of my project, I noticed that everyone mentioned how much of a pain it was to get in touch with the right person in the FAA. They all talked about sitting on the phone for hours, constantly being put on hold and transferred from office to office. Instead of going through the hassle, I thought it would be a good idea to look into local colleges that have launched similar weather balloon experiments. I assumed someone with experience might be able to point me in the right direction. I almost immediately found a link to a URI professor's webpage. His name is John Merrill and he is an atmospheric chemist. John has launched over 200 free floating weather balloons in the last 4 years, as part of a research project to collect information about ozone concentrations in the atmosphere. I figured why not give him a call and see if he can point me in the right direction on who to contact within the FAA. He was interested in my project after I explained it to him and he was willing to help out in any way. He gave me a phone number on who to contact to get permission to launch. I then had to contact the FSDO located in Boston MA. They asked me a few questions about the project, made sure everything followed regulations, and then gave me another umber to contact the day of the launch. They said that the number was to a radio tower at T.F Green airport. I have to call the tower a half hour before launch to let them know about the balloon, and then call them within a half hour after it touches back down so they're kept in the loop the whole time.