I sent stuff to space

A few months ago I was approach by some very-nice co-PhDs doing one of those cool balloons that fly very very high for some purpose, then burst it and open an small parachute for trying to soft-land the payload.

I was interested of course because is not very common to be able to say “I have sent some stuff to space”, I definitely wanted to have the possibility of saying that.

The project was titled:

Investigating stratosphere micrometeorite contamination

Abstract:

Meteorites and micrometeorites are important “peek-holes” to the formation of our solar system and processes on other planetary bodies. The field of meteoritics have received a lot of attention due to controversies around signatures of “life” in Martian and other meteorites, and contamination is a big problem when studying meteorites. In this study, carried out as part of the global space balloon challenge (GSBC), a Kaymont 1200 weather balloon equipped with an experiment box was used to transport micrometeorite analogues up to 33000 m. The experiment box opened between 25000 to 30000 m exposing the samples to potential microbial contamination. It is hoped this work may help provide important insights on the significance of contamination of micrometeorites in this level of the stratosphere. The experiment box was successfully retrieved, and scanning electron microscope analysis has shown probable upper atmosphere contamination consisting of NaCl salt, calcium carbonate grains and sulphur-bearing dust grains, which are possibly volcanic aerosols. Culturing of samples in the laboratory is ongoing, to assess the degree of biological contamination and to see which type of sample, if any, that the potential microbes preferred to hatch on to.

So, they asked me if I could open a hatch at certain altitude and then close it. This was to expose the samples to the atmosphere at that altitude, close it and thats it.

I started to work… My idea was to use one of my flight controllers (an multiwii one) that has a precision barometer and can certainly drive servos and just write a small snip of code to activate the servo and close it.

After reviewing the multiwii code and the mission specifications, I decided to use the CAMTRIG function in the multiwii code and just add an “if” that will monitor the altitude and if it was above 25,000 meters then open the hatch and “lift a flag”, if the altitude value was more than 30,000 meters then close the hatch. The flag or lock was just to prevent the hatch to open when the ballon was plummeting down to the center of the planet.

I had to make sure the barometer was going to work at that altitude and also if the multiwii was designed for such big integer… The altitude is an 32-bit integer and have a range of -2,147,483,648 to 2,147,483,647 cm, so, no problem there.

I did a test of this using smaller altitudes, from 50cm to 150cm and it worked flawlessly, I’m surprised of the precision of the barometer and how well all the multiwii code works!

So, I gave to the team my FC, a BEC to power it the controller and the servo and a small battery. Everyone else did their awesome job and the balloon was launched, everything worked great, the balloon landed and payload/cargo is safe. We have top men working on it right now. Who? (you might ask…) TOP…. MEN.

And now I can proudly say:

I have sent some stuff to space!

I have sent an MultiWii to space!

Part of me has being in space!

… haha someone stop me.

The code looked like this:

[code language=”cpp” title=”MultiWii code to open a hatch”]
#if defined(CAMTRIG)
  #define OPEN_HATCH  2000  // µs
  #define CLOSE_HATCH 1000
  //Altitudes
  #define OPEN_AT_ALT 250000 // cm
  #define CLOSE_AT_ALT 300000 // cm
 
  // If altitude is between the two values, open the hatch
  if(alt.EstAlt > OPEN_AT_ALT && alt.EstAlt < CLOSE_AT_ALT && !Descendlock){    
servo[2] = OPEN_HATCH;   }  
// Keep servo close in any other case  
else{  
servo[2] = CLOSE_HATCH;
if(alt.EstAlt > CLOSE_AT_ALT) Descendlock=true;
}
#endif
[/code]