PICAXE not in Space

srnet

Senior Member
#1
$50SAT the PICAXE powered PocketQube satellite has recently returned home, as you can see if you try to track its current location;

http://www.satview.org/?sat_id=39436U

With a de-orbit window of 2 hours, we have no idea where its remains ended up.

It was fun.

There are now no PICAXEs in space that I am aware of.
 
#5
Yes, it was a fascinating project.
@srnet - I am intrigued know how they were able to track such a small device and determine when it fell to Earth, long after it had gone silent?
Or was it just theory, based on the orbit it had been on? (I think this unlikely if the estimate was accurate to +/- 1hr?).
 

srnet

Senior Member
#6
Yes, it was a fascinating project.
@srnet - I am intrigued know how they were able to track such a small device and determine when it fell to Earth, long after it had gone silent?
Or was it just theory, based on the orbit it had been on? (I think this unlikely if the estimate was accurate to +/- 1hr?).
It was tracked by NORAD, orbital perameters updated weekly.

There was some dispute before launch as to whether NORAD could track something so small, but I was since it had a radio beacon I was able to get an accurate fix on it with a directional antenna. The fix I got was within 2 seconds of its position as predicted by NORAD.

These days the FCC in America will not apparently give permission for satellites smaller than a cubsat (10cm cube) due to the difficulty of tracking them, despite the obvious evidence that they can track something 1/8th that size just fine.

The tracking is not continous, and accurate predictions of the exact timing of a de-orbit are not possible.
 

AllyCat

Senior Member
#7
Hi,

the FCC in America will not apparently give permission for satellites smaller than a cubsat (10cm cube) due to the difficulty of tracking them, despite the obvious evidence that they can track something 1/8th that size just fine.
Yes, Radar uses "millimeter wavelengths" so at least "military grade" equipment should be able to track anything significantly larger than that. The only issue with a (metal) cube is that its flat sides may reflect the radio waves away in other directions, rather than returning them directly to the (Radar) transmitter. But small satellites are not going to have a stabilised orientation, so will tumble and at least sometimes be "visible" (to Radar, if not optically).

However, to predict the time (let alone location) of "re-entry" is very difficult because of the unpredictable drag of the upper atmosphere. The Humanity Star satellite re-entered about 5 times sooner than intended/expected, because of its elliptical orbit (i.e. briefly dipping into the upper atmosphere once each orbit) and its unusually large diameter to weight (i.e. drag/mass) ratio.

Cheers, Alan.
 
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