1. Amateur Near Space Exploration
The Do-It-Yourself
Space Program

2. Public Access To Space Is public access about to begin?
Why wait when we have something nearly as good and certainly more affordable?
Currently, the price of sending a payload to LEO is on the order of $10,000 per pound. Hardly affordable for most people. However, some corporations, like SpaceX, are in the process of changing the cost of space access.
Even after SpaceX brings down the cost of spaceflight, it will probably be too much for most of us.
However, since 1987, amateurs space explorers have been accessing something very similar to space but for a cost of approximately $10 per pound.

3. Near Space as an Alternative to Space
The region that amateurs have sending payloads is called near space. But where is near space and how are amateurs reaching it?

4. Where is Near Space? Controlled Airspace (ICAO) Outer Space (FAI)
Near Space is between
Class A Air Space
(60,000 ft)
and
Outer Space
(328,000 ft)
First, we need to understand how air space is divided up for the purposes of aviation.
There are several classes of air space. Some of them, like class B, C, and D are related directly to airports. Class A on the other hand is more general and it reaches up to an altitude of 18.3 kilometers. In the United States this is called flight level 600 (60,000 feet). Above Class A airspace is class E airspace, which is uncontrolled airspace.
Outer space begins at an altitude of 100 kilometers. Have you ever wondered why an altitude of 100 kilometers was chosen as the boundary for outer space by organizations like FAI? It’s because of the speed an aircraft needs to fly at that altitude. As altitude increases, air pressure at that altitude decreases. The amount of lift a wing generates (an aeronautics issue) depends on the amount of fluid (liquids and air are considered fluids) flowing over the wing’s surface per unit of time. As the air density gets lower, the wing must travel faster in order for the same number of molecules to flow over it per second. Von Karman calculated that at about 100 km, the air speed of a wing needed to generate sufficient lift was equal to the orbital velocity of a satellite traveling at that altitude (an astronautics issue).
Therefore, wings can no longer fly at altitudes above 100 km, instead they orbit.
The next set of slides will illustrate how environmental conditions change as a device climbs into near space.

5. The air pressure, which is closely correlated to air density, decreases exponentially with increasing altitude. The rate at which air density decreases depends on factors like planetary gravity, air temperature, and gas density. The change in altitude needed for the air density to decrease by a factor of e (1/2.718 or 35%) is called the scale height of the atmosphere. The scale height of Earth’s atmosphere is roughly 8 km.
Humans don’t think in terms of 1/e very well, so there are three rules of thumb we can use to estimate the change in atmospheric pressure as a function of increasing altitude.
The air density changes by a factor of 3% per 300 meters
The air density changes by a factor of 50% per 5,500 meters
The air density changes by a factor of 90% per 15,250 meters
Note that using air pressure is a good measure of air density since they only differ by 1% from each other at an altitude of 30,500 meters.

6. It’s nearly everyone’s experience that the air temperature decreases as they climb higher above the ground. This remains the case as long as one remains in the Troposphere.
Fewer people know that the air temperature increases again with altitude once you enter the Stratosphere. The reason the temperature begins increasing again is because of the ozone within the Stratosphere. It blocks solar ultraviolet radiation from reaching the surface by eventually turning ultraviolet energy into thermal energy.

7. Subatomic particles originating from beyond Earth, or Cosmic Rays are atoms from the stars. They were discovered in 1912 by Victor Hess. He detected their cosmic origin by traveling in balloons with radiation detecting instruments. He discovered that the intensity of the radiation his instruments detected increased as he climbed higher into the atmosphere. This indicated an extraterrestrial source for the radiation.
One source of cosmic rays is the sun while other sources probably include supernova explosions or possibly even supermassive blackholes in the center of galaxies. These are called primary cosmic rays, as you see shortly. Most primary cosmic rays are the nuclei of atoms, like hydrogen. When primary cosmic rays enter the atmosphere, they smash into molecules of oxygen and nitrogen. The collision between a primary cosmic ray and a nucleus creates a shower of additional energetic subatomic particles called secondary cosmic rays.
The peak in the cosmic ray flux at around 18,900 meters is called the Pfotzer Maximum. This is the altitude at which secondary cosmic ray production peaks. Below this altitude, fewer secondary cosmic rays are produced and many are losing so much energy that they can no longer be distinguished from atoms in the atmosphere.
One final note. Technically it’s an error to refer to cosmic rays as “rays”. Rays are electromagnetic radiation and cosmic rays are for the most part, subatomic particles and nuclei. But for historical purposes, we still refer to them as rays.

8. The Near Space Horizon Black Skies Curved Horizon
The sky is blue because of Rayleigh scattering, or the preferential scattering of blue light over red light by molecules in the atmosphere. No matter which way an observer on the ground looks, he or she sees blue light from the sun.
The situation changes as an observer approaches near space. The reduction in the amount of air means less blue light is scattered out of the sun’s light. The result is the sky turns darker and the sun more intense. At around 26,000 meters, the sky turns black.
The position of the horizon depends on one’s altitude. At the surface, the horizon appears 90 degrees from the zenith. As a balloon climbs higher, it essentially sees over the edge of the horizon. At higher and higher altitudes, The distance to the horizon increases and the angle between the zenith and the horizon also increases. The increasing angle between the zenith and the horizon is called depression of the horizon. At 30,500 meters, the distance to the horizon is over 650 kilometers and the horizon is depressed by five degrees.
One other result of the depression of the horizon is that the Earth’s curvature can be detected in near space.

9. Accessing Near Space Helium/Hydrogen Filled Weather Balloon
Recovery Parachute
One or More Modules
Sending experiments into near space doesn’t require fiery or noisy rockets. Our rocket booster is silent and consists of a latex weather balloon and its propellant of hydrogen or helium gas.
The balloon carries a recovery parachute, at least one tracking module, and several student designed experiments called BalloonSats (balloon satellites). The near spacecraft, as I like to call it, is around 10 meters tall and climbs at a rate between 300 and 400 meters per minute.
The balloon expands in volume as it climbs higher. At its maximum volume, the balloon reaches a diameter between 6 to 12 meters across, depending on the size of balloon used. In clear skies, the balloon can be seen with the naked eye as a star in the sky. The balloon bursts by itself, so the near spacecraft designer doesn’t have to make it burst.
The string between the balloon and top of the parachute is called a load line. The load line is at least 3.5 meters long in order to prevent the popped balloon from falling on top of the parachute and collapsing it.
A typical ascent takes about 90 minutes and the descent an additional 45 minutes.

10. Mission Support Flight Prediction Software
- CUSF Landing Predictor (predict.habhub.org)
- LiftWin
Tracking Software
- APRS (mobile)
Findu.com (mission control)
APRS.fi
Prior to launching a weather balloon, the flight crew makes predictions of the flight using software called the CUSF Landing Predictor. Prediction software lets the flight crew determine a safe place to launch a balloon. If a recovery zone looks like a bad place to land the near spacecraft, they will select another launch site and run the predictions again. Bad landing zones include in the middle of towns, nuclear power plants, large lakes, the ocean, military bases, and North Korea.
Some of the inputs to the landing prediction software includes ascent rate and maximum altitude. Those values are sometimes selected based on past experience and other times from a program called LiftWin.
LiftWin is a program to determine the flight characteristics of a balloon and its payload. The software makes calculations of ascent rate and maximum altitude based on the size of the balloon, its payload weight, and amount of lifting gas.
After launch of the balloon, the flight crew chases after it using tracking software. In the United States we are permitted to use amateur radio to track the balloon. Onboard the near spacecraft is an amateur radio tied to a GPS receiver and radio modem called a TNC (terminal node controller). This three part tracking system sends position data of the balloon (latitude, longitude, and altitude) once per minute to any ground station prepared to receive and decode it. This tracking system is known as APRS (automatic packet reporting system) and very popular in the US.
For people without an amateur radio license, they can use Findu.com or APRS.fi to track the flight of the balloon. This is because some amateur radio operators forward the APRS reports their radios receive to the Internet. This is especially useful for schools who have designed BalloonSats. The students can act as Mission Control for the flight that is carrying their experiment(s).

11. Beginning A Near Space Program
Ham License
APRS
Build Airframes
Build Avionics
Parachute
Experiments
Support Equipment
Software
Procedures
How does one go about starting their own program of amateur near space exploration? I did the following steps. However, in Europe, the steps might be slightly different as I know in some cases that amateur radio cannot be transmitted from a balloon.
First I got a radio license (ham license). In fact I never would have heard of a near space program back in 1994 if I hadn’t earned a radio license in 1992.
After earning a license, I started experimenting with APRS – a form of digital radio. I liked the idea of combining digital radio with GPS receivers to create tracking and science systems. It was only later I discovered that hams were launching trackers on weather balloons to collect amazing data. As soon as I learned this, I was hooked on amateur near space exploration.
The airframes for modules in a near spacecraft are made from Styrofoam, or expanded polystyrene plastic. Styrofoam is light weight a an excellent insulator. Like real spacecraft, weight is of concern and no one wants to waste mass on airframe would it could go into science payload. Styrofoam is cut with a sharp hobby knife and attached together using hot glue (melted plastic). The Styrofoam box is then covered in tape or fabric.
The avionics, or aviation electronics is generally the APRS tracker plus any data logging capability built into the tracker. I like to run the data logging electronics parallel to the tracker, that way they can share the same battery and GPS receiver. By using programmable microcontrollers like the PICAXE, BASIC Stamp, or Arduino, the data logger can be smart enough to actually run experiments rather than passively record data. Examples include changing the position of a camera with a servo, operating a camera, or releasing dropsondes.
No one can launch a weather balloon in an unsafe manner. Therefore, a parachute is required. Some people purchase their parachutes from rocket companies like RocketMan while I personally like to make my own parachutes. The parachute should brightly colored in order to standout in a field. Parachutes are normally made from non-porous fabrics like ripstop nylon. For the typical near space flight carrying 5.5 kilograms of payload, a parachute with 2 meter diameter is required. A parachute this size shouldn’t weigh much more than 500 grams.
There’s no sense launching a near spacecraft unless you plan to collect data. At least a camera. Some experiments operate autonomously and others need a microcontroller to operate them. I find that young children like to perform exposure experiments in order to see what the near space environment of intense cold, increased ultraviolet radiation, and near vacuum does to everyday items. This can be a good way to teach young children about variables in science; controlled variable, independent variable, and dependent variable.
To launch a near spacecraft, one needs support equipment like a balloon filler, digital scale, duct tape, nylon cord, and ground cloth. The filler is a gas regulator with hose and end modified in order to fit inside a weather balloon. The digital scale measures both the weigh of the payload and the amount of life the balloon generates. Typically I fill the balloon with enough gas until it lifts 1.4 kg more than the payload weighs. This typically results in an ascent rate of 5 m/s. You can’t do science without duct tape. Duct tape is used to secure the balloon’s nozzle to the filler. That prevents the balloon from slipping off during the filling process. I also use the tape to add strength to knots tied in the load line. Since tying knots weakens cords, its important to strengthen then using duct tape. Nylon cord is the load line used to attach the balloon’s nozzle to the parachute’s apex. A twisted nylon cord with a diameter of around 3 mm is sufficient for this purpose and can be found at small hardware stores. Balloon filling is done outdoors, especially when using hydrogen gas. Because of the risk to the balloon created by rocks, dirt, and weeds, the ground is first covered with a ground cloth before the balloon is attached to the gas filler. I made my ground cloth by sewing two bed sheets together.
Before even starting a program, make sure you know how to run the software involved. For example APRS, which is the tracking software. This includes running the software in ground stations that follow after the balloon and running the software inside the tracker going up with the balloon. Other software includes Liftwin, the landing prediction website, and the radio tracking websites launch crews can use to follow after the balloon.
Finally, you’ll need a set of procedures. Ask yourself how you plan to preflight test the near spacecraft, connect the modules together, weigh the near spacecraft’s weight and the balloon’s buoyancy, attach and fill the balloon, carry launch gear and gas cylinders, and launch the balloon. Then memorize the procedures.

12. A Near Space Mission
The following slides show what an average near space flight looks like.
First the balloon is filled with a buoyant gas, helium in this case since students were involved in the filling.

13. A Near Space Mission
The balloon’s load line is gently extended to raise the balloon. Then the parachute follows. Each module is then released. Everyone involved with the raising of the near spacecraft is wearing gloves. Gloves prevent anyone from getting string burn should the wind blow the balloon away.

14. A Near Space Mission
When the last module is ready to be released, the launch crew likes to ask the audience to give a brief countdown. At zero the last module is released and the near spacecraft begins its ascent.

15. A Near Space Mission
After release, the launch crew switches over to chase mode. Our vehicles are equipped with radio tracking equipment so we can drive after the balloon. Since we know with great certainty where the balloon will land, our driving path is well understood in advance. If the balloon won’t land very far form the launch site, the chase crew often has time to stop at convenience stores for some refreshments.

16. A Near Space Mission
This is what everyone in the chase team wants to see, the near spacecraft after landing inside an open field that’s easy to access and find.

17. On this flight, the top module recorded images of the ground and the secondary transmitter below. This is about 30 seconds after launch.
“Hey, I can see your backyard form here.”

18. This is high over an airport in Kansas (central United States)
This is high over an airport in Kansas (central United States). The balloon is far above the of its Class C airspace.

19. This is a very unusual image
This is a very unusual image. We launched multiple near spacecraft together and this one has nearly the same buoyancy and weight as the near spacecraft recording this image. The image was recorded at 15,250 meters. For a sense of scale, the orange tracking module in this near spacecraft is 30 centimeters across. At launch, the balloon was only 2 meters tall.

20. This image shows two BalloonSats suspended at the bottom of the near spacecraft. Far below are farm fields in Kansas. The near spacecraft is so high that the ground has a bluish tint from the amount of atmosphere below. Students could make maps from images like these.

21. Why Near Space? STEM Education Space is Motivating Real Science
Since I am a teacher, I want to share some reason why I think near space is useful in education.
First, STEM, or science, technology, engineering, and math education is rapidly becoming a part of a high quality education. The extent at which these four fields affects our lives is increasing rapidly. In fact, most careers require some background in STEM and they are among some of the highest paying jobs. Projects, like robotics, can teach some components of STEM very well, but near space has the ability to teach all four components in an integrated fashion.
Another reason near space can be very effective is because space exploration is very exciting to young students. That excitement helps to push students to work harder on their school projects. The more invested students are in a project, the more they are likely to learn.
Finally, near space is more than a cook-book science experiment. Students have to engineer a structure to operate their experiment and collect data remotely. They will use technology dataloggers and programmable microcontrollers to operate their experiments. Finally, no data makes sense until after mathematical processing. This includes creating meaningful graphs to display the data. Before designing an experiment, students should be required to research their experiment and at the end, to write up a final report. All these requirements are exactly what scientists do in their daily jobs.

22. Questions?
I hope you find amateur near space as exciting as I do. I have launched over 161 flights since 1996 that have carried over 350 student experiments. My highest mission reached 25,365 meters and my lowest reached only 2.5 meters when the load line snapped at lift off. I have learned a lot in creating, flying, and analyzing these missions and I think students will too.
You can read about my adventures on my website, NearSys.com.
Thank you for listening to my presentation and I would be happy to take questions.

23. Near Space isn’t as Hard
Space is Hard
- James Oberg
Near Space isn’t as Hard