Lost at Sea

Have you seen my payload? It was last seen leaving the ground at 11:15 CST near Somerville, AL, with the callsign of N4TXI-11.

Below can be seen the last known position for my payload at 20:39 EST, on December 18, 2004. Over 626 miles from its launch site, the balloon was still floating at 103,000ft. in a jet stream blowing 110mph due East out to sea (or is that out to ocean?) Since it was night (no UV radiation to deteriorate the balloon) and the balloon was showing no signs of falling, it is entirely possible that the balloon continued floating all night long. At sunrise, it would have been over one thousand miles off the US coast - it might have even gone to Bermuda! We'll see how well my reward sticker holds up in saltwater, eh?

Here is a plot of the altitude verses time during the flight. Note the drop in altitude when the sun set and the balloon lost a little lift. It had just enough buoyancy left to settle out around 103kft.

Confirming the setting of the sun, here is a plot of the internal temperature of the payload. I wasn't aware how much solar radiation played in maintaining heat in the Styrofoam enclosure, but now I know. Note how the temperature plummeted after sunset! My temperature sensor saturates above -40 degrees, which is why the plot asymptotically approaches that value. I'm certain it was much colder - I just wasn't equipped to measure that cold.

Finally, here is a plot showing why the payload finally stopped updating. It was a race between the battery Voltage dropping and the balloon leaving the coast. The battery voltage took a turn for the worse as they got very cold, and the radio stopped transmitting at a pack voltage of 3.2 Volts. By then, the batteries were pretty far gone. While I wish it could have run longer, I'm thankful that the payload was able to report a couple times after it was over the ocean.

Here is a picture of the payload with the package open before extra insulation was stuffed inside:

And here's one of the last times the payload was visually spotted, hehe: