Aug 2, 2008

HALE, Another update...

First, I'm sad to say that the recently posted (& fantastic!) image of balloon shards falling to earth was not from my payload Gypsy, but from Eric Wang's SLR payload. It seems that for some reason (Gremlins? Bionicles? Jack Stone?), Gypsy's SD card is empty - the payload took an initial picture upon start-up (as it's supposed to, to show it was working), but for some reason it didn't work after that. I've no idea what went wrong, and it's very troubling (& you can BET I'm going to try to figure it out)... but that's some of the risks & mysteries of this sort of thing. To be honest, overall I'm still amazed at how well it went.

The team took a big gamble on having Lil' Joe free-fall - it was risky (for their equipment), and required them to do three retrievals when usually they have to do just one. Yet Lil' Joe worked. Well, close anyway... I'll put up some data graphs soon, but Lil' Joe had a rough ride, slamming into the desert at about 35 mph with a tangled & partially collapsed parachute. The impact was hard enough to smash out the bottom of the payload, ejecting some of the cushioning and the ascent tether, but mysteriously not ejecting the NXT & SPOT unit. The impact stopped a small GPS datalogger that had been along for the ride, but it finally recovered seven minutes later. Lil' Joe's program worked flawlessly, logging acceleration data at a rate of 30 Hz for a two minute period right after it was cut free, estimating its own height and adjusting the free-fall time based on this (it ended up holding off on "pulling the rip cord" for 61 seconds or so... and the parachute had absolutely no effect upon deployment, as the air was just too thin), finally reaching the ground just 15 minutes later. In the process it reached speeds of 150+ mph, experienced accelerations of more than 4 G's, and was violently spun about... and it took notes the whole way down. I'm very happy. But I suspect there's a very motion-sick minifig that will have some harsh words for me.

Gypsy, with the exception of the camera issue, did even better, taking literally thousands of records during the ascent and descent, operating the platform and camera flawlessly (despite the fact that the camera apparently didn't turn on), monitoring temperatures, running the heaters, testing sensors... and it all worked. The sensors worked the entire mission, exactly as expected... including the amazingly accurate prototype pressure sensor and the protoboard from HiTechnic. The all-LEGO, no glue attachment to the balloon, exposed to accelerations of at least 3 G's, and chilled to a bitter (and potentially brittle) -60° C, did not fail, and in fact it seems the LEGO turntables were still able to move under those conditions (although at one point they may literally have "iced up", freezing solid during the descent, even this does not seem to have program the program, as I had planned on the possibility). It even detected when the balloon burst, and switched to a different command script to try to capture the chaos of descent... something I had no way of adequately testing at home. In short, with the exception of the mystery camera issue, everything worked as planned, and Gypsy has returned a virtual second-by-second diary of it's mission to near-space. In the end, I'm very pleased with how it went, and there's a lot I (& hopefully others) can learn from it.

Eric Wang has been producing some amazing images and data from this mission already. In addition to the suitable-for-framing image of the balloon shards over the Earth, you can see some of the other things they've put together in this post. And they've started a permanent image gallery here:

HALE Mission Photo Gallery

(there's a chance that in one or more of those photos, one balloon took a picture of the other. Anybody want to look?). The payloads will be shipped back sometime soon, and I look forward to seeing exactly how the LEGO construction of both Gypsy & Lil' Joe handled the mission. As long as I'm throwing out links, a few more to keep everything handy:

Timelapse movie of the balloon launches

Main HALE website (with links to videos, including timelapse ones, more pictures, etc.)

HALE Discussion group (if you want to see how we organized this, and as we all discuss & exchange the data from the mission).

--
Brian Davis

PS- The green line in there is Lil' Joe :)

2 comments:

David Levy said...

"there's a chance that in one or more of those photos, one balloon took a picture of the other. Anybody want to look?".

I have not examined all of the images but this one appears to have a small speck in the upper left quadrant that may not be a sun related camera effect.

Rick Rhodes said...

There's been a lot of excellent coverage of your payload launches. Here's my favorite headline of a story I saw this morning:

"Lego Robots Sent Into Space to Snap Photos and Annihilate Us With Lasers"

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