Hard to believe, but I flew my 99th near space mission this weekend as NearSys 11N. I traveled to Valley, Nebraska to launch a ballon in conjunction with friend, Mark Conner. Mark and I go back to 1998 when we met at the St. Joe Hamfest in Missouri.
We ran into a small problem on this flight that ended up creating a bigger headache before it was all over. The helium tank we received was not properly topped off (about 20% low). As a result of the unexpectedly lower volume of helium, we were forced to remove some payloads. The reduction in payload weight also meant the parachute would descend slower, permitting a longer recovery.
To make a long story short, recovery should have occured in farm fields south of Anita, Iowa. Instead, recovery occurred in a small patch of woods near Adair. As is typical, the near spacecraft recovered on the very top of the trees. It took about an hour for Mark and me to retrieve the payload.
You can view the flight data on my website at, http://nearsys.com/arhab/flightdata/2011/n/index.htm.
Mark posted pictures at, https://picasaweb.google.com/111334632256807627139/NearSysFlight12Nov2011
Onwards and Upwards
Showing posts with label NearSys. Show all posts
Showing posts with label NearSys. Show all posts
Tuesday, November 15, 2011
Sunday, January 23, 2011
NearSpace UltraLight
The UltraLight kit is just about ready for sale (I'm waiting for some PICAXE-28X's and to complete the directions). I've added a bunch of new stuff to the kit, including a control panel, commit tag, audio beacon, and antenna, as you can see in the picture above.
The NearSpace UltraLight is the easiest way to begin a near space program. The kit can be assembled over a weekend. All you need to complete the kit is decide on your battery and its termination (I use Anderson Powerpoles). If you have cameras, then you'll also need to select a termination method for them (I recommend Dean's micro plugs).
NearSys sells a GPS receiver kit. It is designed for flight computers like the UltraLight. The UltraLight and GPS coupled together is a complete flight computer. Build an airframe and purchase a parachute and you can begin exploring near space.
About the Flight Computer
The UltraLight digitizes four analog sensor voltages, operates three digital experiments (like geiger counters), controls two cameras, and positions two servos (the servos have their own battery). The UltraLight's audio beacon makes enough noise that you can locate the near spacecraft in tall grass or corn fields. The control panel lets you program the flight computer and download data without having to open the airframe. You can also communicate with the flight computer while launch crews are filling the balloon (perhaps to verify sensor operation prior to launch). The flight computer's Tiny Trak is also assessible through the control panel (but not while the GPS is plugged in) The control panel indicates the near spacecraft's power status and the status of the Tiny Trak (that is, when it is transmitting and when its GPS has a lock). The bright red commit tag screams a reminder to begin the mission before releasing the balloon. That way you can power up the near spacecraft and wait for a GPS lock before recording mission data (who wants a bunch of data on the ground when you're headed to 100,000 feet?).
The Onboard Tiny Trak
The APRS tracker is built right into the flight computer. The 500 mW transmitter and dipole antenna will let you track the entire mission. Since the transmitter is set for 144.390 MHz, I-Gates can put your tracking data online, allowing everyone in the world to track your flight (very useful when your chase vehicle is located in the null of the antenna).
Mission Data
Mission data is stored in 32kB of memory. After recovery, reprogram the flight computer to download its data right into your PICAXE Editor (with its built-in terminal program). This can be done right in the field if your want (bring your netbook along). The data is then saved as a text file and opened in Excel. You can be generating results from the mission at the post recovery lunch!
It may take another week to get the kits packed and the directions in their first draft. Meanwhikle, feel free to contact me if you have questions.
I guess it's time to start a forum!
Saturday, February 20, 2010
Clearing Misconceptions About Near Space Missions
I was thinking about these topics earlier this week and thought they ought to be cleared up. So if you'll permit me.
Most people are familiar with the concept that motion is relative. This means that motion to one person looks just the opposite to another person who is not sharing that motion. It's all a matter of your frame of reference.
When we discuss things like the ascent rates and maximum altitudes of a balloon, we really should be discussing these issues in their more accurate frame of reference, that of the balloon. In reality, the balloon is holding still and the earth (along with the atmosphere which is firmly attached to the earth via gravity) is falling. Apparently this occurs because when we put helium into a balloon, we're removing it from the earth and its atmosphere (I'll refer to these as the earth-atmosphere system). When you remove low density material from the earth-atmosphere, you're increasing its average density. Recall that dense objects sink and less dense objects can float. The denser earth-atmosphere now wants to sink. And as long as the filled balloon is firmly attached to the earth's surface (via gravity), like by a person holding the balloon's load line or by tying the load line to a helium bottle, the balloon will hold up the earth. So those of you who are holding the filled balloon before launch, you're really holding the earth-atmosphere up. Think about that next time.
Once the balloon is no longer tied to the earth, the earth-atmosphere falls away. As the earth and its atmosphere fall away, the balloon is surrounded by less and less dense air. The balloon expands as a result. Since the helium is trapped inside the balloon, there are no further changes in the earth-atmosphere's density and it falls away at a constant rate that is dictated by the friction of the air around the balloon. The atmosphere, which remember is firmly attached to the earth, can only slide pass the balloon at a limited rate. Friction is why the earth does not fall away from the balloon infinitely fast. Many of you have no doubt noticed that at some where around 30-40,000 feet, the balloon appears (and let me stress appears) to rise faster. This is the result of the earth-atmosphere slipping around the balloon faster because of changes in air density and balloon size. This is pretty obvious if you recall that the force of friction is based on factors like surface area and density.
At the point where the atmospheric pressure around the balloon is low enough, the balloon bursts and releases its helium back into the atmosphere. This mixing of helium back into the earth-atmosphere system decreases its average density and let's the earth and atmosphere float back up to the balloon. The air rising around the balloon payload makes it tumble (due to turbulence) and inflates the parachute. The mixing of the balloon's helium with the atmosphere occurs very rapidly and therefore, the change in the density of the earth-atmosphere is very fast. This makes the earth-atmosphere begin to rise very quickly. At the earth-atmosphere rises back up to the balloon, the air becomes denser and the parachute creates more drag, slowing the ascent of the earth-atmosphere. Therefore, we see the initial ascent of the earth-atmosphere is very fast at the start, but over time, the ascent rate slows down until the balloon and earth make contact. At that point, the earth-atmosphere system and balloon are back in equilibrium and the motion comes to an end.
Now, since the days of the Greeks, we've known the world is round or spherical. There is no friction between the earth-atmosphere system and outer space. So when you go on a balloon chase, your car tires are pushing the earth and making it rotate the opposite direction. Let me stress, your car is NOT MOVING!! Therefore, it would help if everyone in their cars would travel together and go the same direction. If your chase teams will push the earth in the same direction, you'll rotate the earth in the same direction more quickly and get the earth rotated into the proper alignment with the balloon more efficiently. Therefore, it is imperative that we prevent chase crews from leaving their homes from the opposite direction, as this pushes the earth in another direction at the same time. When one big and heavy chase truck tries to push the earth to the west, the rest of our lighter cars trying to push the earth to the east suffer. I for one do not want to see my gas mileage decrease because of this. So please be polite to everyone else and follow along with the rest of the pack.
This also highlights the importance of using the balloon launch announcements system. There are some weekends with multiple balloon launches. If they are occurring at the same time, our cars are fighting each other to rotate the earth to our proper positions. So be considerate and coordinate your launches with other teams across the country.
Just doing my part to clear things up,
Paul
(Next time I'll explain the relativistic effects of a balloon launch and why the Twin Paradox makes use younger after each balloon flight)
Most people are familiar with the concept that motion is relative. This means that motion to one person looks just the opposite to another person who is not sharing that motion. It's all a matter of your frame of reference.
When we discuss things like the ascent rates and maximum altitudes of a balloon, we really should be discussing these issues in their more accurate frame of reference, that of the balloon. In reality, the balloon is holding still and the earth (along with the atmosphere which is firmly attached to the earth via gravity) is falling. Apparently this occurs because when we put helium into a balloon, we're removing it from the earth and its atmosphere (I'll refer to these as the earth-atmosphere system). When you remove low density material from the earth-atmosphere, you're increasing its average density. Recall that dense objects sink and less dense objects can float. The denser earth-atmosphere now wants to sink. And as long as the filled balloon is firmly attached to the earth's surface (via gravity), like by a person holding the balloon's load line or by tying the load line to a helium bottle, the balloon will hold up the earth. So those of you who are holding the filled balloon before launch, you're really holding the earth-atmosphere up. Think about that next time.
Once the balloon is no longer tied to the earth, the earth-atmosphere falls away. As the earth and its atmosphere fall away, the balloon is surrounded by less and less dense air. The balloon expands as a result. Since the helium is trapped inside the balloon, there are no further changes in the earth-atmosphere's density and it falls away at a constant rate that is dictated by the friction of the air around the balloon. The atmosphere, which remember is firmly attached to the earth, can only slide pass the balloon at a limited rate. Friction is why the earth does not fall away from the balloon infinitely fast. Many of you have no doubt noticed that at some where around 30-40,000 feet, the balloon appears (and let me stress appears) to rise faster. This is the result of the earth-atmosphere slipping around the balloon faster because of changes in air density and balloon size. This is pretty obvious if you recall that the force of friction is based on factors like surface area and density.
At the point where the atmospheric pressure around the balloon is low enough, the balloon bursts and releases its helium back into the atmosphere. This mixing of helium back into the earth-atmosphere system decreases its average density and let's the earth and atmosphere float back up to the balloon. The air rising around the balloon payload makes it tumble (due to turbulence) and inflates the parachute. The mixing of the balloon's helium with the atmosphere occurs very rapidly and therefore, the change in the density of the earth-atmosphere is very fast. This makes the earth-atmosphere begin to rise very quickly. At the earth-atmosphere rises back up to the balloon, the air becomes denser and the parachute creates more drag, slowing the ascent of the earth-atmosphere. Therefore, we see the initial ascent of the earth-atmosphere is very fast at the start, but over time, the ascent rate slows down until the balloon and earth make contact. At that point, the earth-atmosphere system and balloon are back in equilibrium and the motion comes to an end.
Now, since the days of the Greeks, we've known the world is round or spherical. There is no friction between the earth-atmosphere system and outer space. So when you go on a balloon chase, your car tires are pushing the earth and making it rotate the opposite direction. Let me stress, your car is NOT MOVING!! Therefore, it would help if everyone in their cars would travel together and go the same direction. If your chase teams will push the earth in the same direction, you'll rotate the earth in the same direction more quickly and get the earth rotated into the proper alignment with the balloon more efficiently. Therefore, it is imperative that we prevent chase crews from leaving their homes from the opposite direction, as this pushes the earth in another direction at the same time. When one big and heavy chase truck tries to push the earth to the west, the rest of our lighter cars trying to push the earth to the east suffer. I for one do not want to see my gas mileage decrease because of this. So please be polite to everyone else and follow along with the rest of the pack.
This also highlights the importance of using the balloon launch announcements system. There are some weekends with multiple balloon launches. If they are occurring at the same time, our cars are fighting each other to rotate the earth to our proper positions. So be considerate and coordinate your launches with other teams across the country.
Just doing my part to clear things up,
Paul
(Next time I'll explain the relativistic effects of a balloon launch and why the Twin Paradox makes use younger after each balloon flight)
Saturday, January 30, 2010
Geiger Counter kit for Near Space
I've started my experiments with the Electronics Goldmine geiger counter kit (C6979). The kit was on special for $70 (down by $10). It operates from a nine volt battery and uses a 555 timer and transformer to boost the voltage to 600 volts. The 555 timer operates at 128 Hz. So when there's a detection of a cosmic ray, there are six (some times five) pulses during the GM tube's dead time.
Gas molecules inside a GM tube become ionized at the passage of a subatomic particle. The ionized gas lets electrons, pushed by the high voltage on the tube, pass from the wall of the GM tube to the center conductor. This makes the GM tube act like a switch at the passage of a cosmic ray. While the tube remains ionized, it's unable to detect other radiation events. How quickly the GM tube clears out this ionization is called the tube's dead time. The shorter the dead time, the more frequently the tube can detect radiation. In near space, I have detected up to 800 counts per minute. On average then, there is 75 milliseconds between detections. As long as the GM tube's dead time is less than that, it should accurately detect radiation levels in near space.
I'd like to try placing a capacitor across the GM tube to smooth out the voltage spikes. If that works, then the flight computer doesn't have to divide the number of counts by six to get the real radiation levels. Perhaps it will also let the tube clear out faster (reducing its dead time).
It's a short video about my experiments to date. Look for an article in Nuts and Volts this year.
Gas molecules inside a GM tube become ionized at the passage of a subatomic particle. The ionized gas lets electrons, pushed by the high voltage on the tube, pass from the wall of the GM tube to the center conductor. This makes the GM tube act like a switch at the passage of a cosmic ray. While the tube remains ionized, it's unable to detect other radiation events. How quickly the GM tube clears out this ionization is called the tube's dead time. The shorter the dead time, the more frequently the tube can detect radiation. In near space, I have detected up to 800 counts per minute. On average then, there is 75 milliseconds between detections. As long as the GM tube's dead time is less than that, it should accurately detect radiation levels in near space.
I'd like to try placing a capacitor across the GM tube to smooth out the voltage spikes. If that works, then the flight computer doesn't have to divide the number of counts by six to get the real radiation levels. Perhaps it will also let the tube clear out faster (reducing its dead time).
It's a short video about my experiments to date. Look for an article in Nuts and Volts this year.
Onwards and Upwards,
Your Near Space Guide
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