Tuesday, 25 August 2015

MADHEN Eggsplorer-1 - We've got the data!

Following the euphoria of the Eggsplorer-1 payload being found six weeks after launch washed up and retrieved from the beach in Terschelling, Netherlands it has been an agonising wait to see what the Dutch police would send back. My impatience got the better of me last week and I contacted them directly to be told that unfortunately due to the awful smell and condition of the box they had simply removed the memory card and had posted that back as requested.

More days past and I was beginning to think irony was going to play a cruel trick and the card after its fantastical journey would end up lost in the post. I shouldn't have been so pessimistic as it arrived today! Along with the card was a detailed map showing the final location and labels from the side of the box.

There was a nice note from the police.

The SD memory card seemed to have had survived more or less intact, though there was some corrosion on the contacts and crucially a small corner of the card was broken off.

The plan was to use the Win32 Disk Imager program to make a direct raw image of the card and work on that copy. I first used a small wad of wire wool to gently clean up the contacts

I was encouraged when I inserted the card into my Microsoft Windows laptop and it was detected, however my heart sank when any attempt to access it or use the imager program was met with an error. I gave it another gentle going over with the wire wool and thankfully was then able to make a image file, the next stage was to extract the precious data.

The card of course contained the Linux based Raspberry Pi file system and in order to access it on a Windows machine I used the freeware linux-reader from DiskInternals which allows access to Ext2/Ext3/Ext4, HFS and ReiserFS file systems within Windows.

It was a simple case of using the "mount image file" option and the partitions were then accessible and everything appeared intact, there were images on the card unfortunately not the "egg in space" image I wanted, just some nice "egg in the clouds" shots.

The telemetry log file confirmed the worst, the flight computer had indeed stopped/crashed at approx 2.5km up and no further images had been captured of the 31km accent into the stratosphere (confirmed by the backup tracker) I had hoped the transmission had stopped because of a fault in the antenna or the radio module board alas this wasn't the case.

On the day of the launch I did have problems with the payload not booting up. It had worked flawlessly under test the previous weeks and I had secured everything in the box ready for the flight. The day before the launch I had spotted there was another balloon going up in the UK at the same time and we had both opted for the same frequency. So at the eleventh hour I was forced to take out the SD card to change the configuration to prevent the transmission clash.

The launch day start up problem was the SD card. I had removed and reinserted it to get it to start up and secured it down with plenty of gaffa tape. Looking at the card now and the fact the broken corner is old damage I am convinced this is the reason for the failure as the card may well have become dislodged due to turbulence.

While slightly disappointed it is still a miracle I have any images at all and can only thank Jan and the Dutch Police again.

I have certainly learned a lot and hope the National Hamfest HAB that I and South Kesteven ARS are flying is more successful

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