The PongSat

5 August 2014: The inspiration for this project came from JPAerospace with their pongsat project. The idea is that you send these people a ping pong ball with something inside like an experiment and they send it up to near space (100km or the Karman Line) for you for free.

So, onto the probe details. I am deciding to go with a cool Russian name for this (because all cool space things are Russian and in memory of the Soyuz 1) and therefore am going to call it Зонд 1 which is pronounced Zond 1 and translates to Probe 1. Since it is K-Labs' first atmospheric probe, it will be very basic and mainly used for testing the durability of the parts and materials in near space. This probe will feature an on-board flight computer, a µSD card memory module, and an altimeter/ barometer/ thermometer sensor. It will be powered by a lithium thionyl chloride (Li-SOCl₂) battery.

Experiment Plan

Since this probe is a bit expensive, I am trying to squeeze in as many experiments as possible. These will either be used for seeing how the parts used stand up in near space and to quench curiosity.

Test the parts being sent up.

Test the effects of cosmic radiation on electronics with minimal shielding.

Gather basic data of the atmosphere e.g. pressure and temperature at altitudes.

See if I can get any particles or microorganisms on the ball.

Mission Patch

10-5-2014: Here is the mission patch I designed for this mission. It went through a lot of consideration and revisions to end up the way it is right now. The design was approved by my "crew" and most people think it is either really good or "meh" status. The design was inspired by many American and Soviet mission patches and strangely enough, I found one Soviet mission patch that looks very similar in terms of the color scheme of the outer rings. Enough talk, here is the patch.

Construction

Here is where I start the documentation of the building of the Zond 1 probe.

8-5-2014: The first step (aside from research) is to pick out a ping pong ball, especially if this is supposed to be the shell of the probe. Here you can see that I am holding the ping pong ball of choice (mainly because it's my only ping pong ball).

8-6-2014: Because an atmospheric probe has to collect data, I decided it needed a flight computer to manage everything. So I found the best small microcontroller I could that I was also familiar with and the TinyDuino came up. So I ordered the basic kit and here it is. A bit expensive but hey, it's Arduino.

8-6-2014: This little thing is the main flight computer. It is a lot smaller than I thought it would be even though I had the measurements for it (still not sure if it's worth the $20 I paid). It is based on the ATMega328 microprocessor running at 8 MHz and 3.3 volts. Hopefully it lasts through the conditions of space.

8-11-2014: This is the µSD card reader that I ordered, it just came and I immediately wrote this. This will keep all the data like height, temperature, and air pressure. Also another thing this will be used for is testing the effects of cosmic rays on digital memory storage devices to see the level of sheilding needed for a real probe.

8-13-2014: The altimeter/ barometer/ temperature module finally came, but in a pretty big box, and considering that this module is a little smaller than the flight computer, it just seemed illogical. Anyways, this is the main sensor unit and will be what our data will come from to be recorded on a µSD card.

8-21-2014: The 8 GB µSD card that I bought. It came with the adapter and a usb adapter all for $9. This is where all of our info is going to go, and it will act like a little blackbox to contain all the special info throughout the flight.

8-23-2014: Now the real work begins. I have gotten most of the parts to start the real development, and I decided to start with the µSD card because that seems easier to use than the sensors. Here I assembled the processor, USB shield and µSD card reader to test the data storage. In the other picture, you can see the output on the serial monitor of the arduino programmer. I ran the test code for the SD library called CardInfo. So pretty much everything looks ok except for the free size of the card because there is a bug in the example code that gives the wrong card size. Otherwise, all is well with this.

9-1-2014: Happy Labor Day! So today I actually had time to work on the electronics a bit more (because playing Tekkit takes a lot of time) and I was able to get the altimeter/ barometer/ thermometer sensor hooked up and tested. It was somewhat difficult because I've never been good at using external Arduino libraries and this required one, so first I had to struggle with getting that to work. After I got that to work, then the hardware started acting up and while it detected the sensor, the TinyDuino couldn't get any data off of it, it just hung. Turns out that even though it uses 3.3V logic, it only works if you hook it up to 5V. So all is well now, you can see my redneck prototyping and then the data returned by the sensor, it seems to be ok, a little off but good enough to gather the data I need.

9-7-2014: Hello y'all, today I tested both of the modules (µSD + sensors) together and wrote code so that the TinyDuino can read data off the sensors and save it on the µSD card. It was a lot of trouble shooting on the software side, the hardware was being good though. I had a lot of trouble mainly with turning the numbers into a string to be concatenated for being stored on the µSD card. In the end all came out ok. I did a speed test to see how fast the unit was pulling and saving data. The code does have a 1 second delay to keep things nice, but I got a rough average of 1.165 seconds per reading/writing cycle which means 0.165 seconds actually dedicated to doing work every cycle. Currently the code records temperature, pressure, altitude, calculated sea pressure and a "calibrated" altitude. Also included is error checking code to say if there is an error and it keeps restarting in hope that it was a minor error that is ok now. The data also appends to the file so in the event of an error, it would append and if the error disappeared, then it would continue writing to the file regardless of how long it was off or in the error state. And of course there is also code for the experiments listed, like cosmic ray detection. Now, since you're dying to download the code to try this out for yourself, click here to download the current code. Keep in mind that the code may be updated for quality purposes or update reasons.

9-14-2014: So I decided to do some work again today, So in order to start shopping for power supplies, I somewhat needed to know the current draw at 5 volts. Considering how simple something like this would have been, I went through a lot of trouble to get it working. Normally I would have it powered off of the usb shield so I wouldn't have to worry about power, but in space it won't exactly have a usb power supply with the usb shield. So the idea was that it could just be powered by some input on the io shield. On normal arduinos, you could power them through the Vin pin, and this one had a Vin pin, so I wired it up to that but nothing happened because apparently it needs 7 to 12 volts. Ok, so there is also a Vcc pin which is like a five volt pin, so I hooked it up to that and the tinyduino worked but the sensor didn't. The only fix was to connect it to the 5 volt pin which already has the sensor connected. Anyways, once that was done, I took measurements of the current draw and at 5 volts, it drew 22 milliamps maximum during a reading/writing cycle and an average of 14 milliamps with a minimum of 5 milliamps. Therefore I can buy a 100 milliamp 5 volt regulator because they are cheap and common. Hopefully the regulator could also solve the battery freezing problem because low efficiency turns most of the power into heat which will hopefully keep the battery from freezing over.