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Mad Scientess Jane Expat

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Is made of win. IS. [20100826|16:44]
Mad Scientess Jane Expat
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[the weather today is |WIN]
[with a hint of |AC/DC - Thunderstruck]

One of the things I like about my job is that I don’t just work on Cassini. I also work on the magnetometer data from the four spacecraft that make up the Cluster mission, which observes the Earth’s magnetosphere. I have spent most of the last couple of weeks adapting calibration code to cope with a range of the magnetometer that hasn’t been used much previously, except when the spacecraft were still on the ground and the instrument was being tested.

Today, I had a breakthrough. Today, I managed to calibrate the Range 7 data.

When the magnetometers switch to Range 7, it means that the spacecraft are very close to the Earth and the magnetic field is strong. The spacecraft don’t spend much time that close to the Earth, so there isn’t a lot of data to work with. I can tell that the calibration hasn’t succeeded (for any range, not just Range 7) when I see a horrid red splodge in the data like the one the red arrow is pointing toward.

Before calibration


The Cluster spacecraft spin at a rate of about once every four seconds, which generates a regular tone in the magnetometer signal. One of the things the data calibration is supposed to do is remove this regular tone. A red splodge like the one above shows that the tone is most definitely still there, and is dominating the signal. Until I get rid of it, the data are not terribly useful.

Below, you can see that the correct calibration parameters have been found and the spin tone is now reduced to an acceptable level. This is terribly exciting to me and about a dozen other people. But I don’t care. Range 7 data, I HAS CALIBRATED IT! \m/

After calibration
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Comments:
[User Picture]From: victorine
2010-08-26 19:22 (UTC)
Rock on! Do you have that brain expandy feeling? (I get that when I solve a particularly hard puzzle, which is why I'm addicted to learning)
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[User Picture]From: nanila
2010-08-26 19:27 (UTC)
Brain expandy feeling! What a perfect description. Yes, that's exactly what it is.

Of course, I'm now celebrating by drinking wine, which is probably killing at least as many neural connections as the ones I just made in figuring this out.
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[User Picture]From: nanila
2010-08-27 09:20 (UTC)
We were talking about TV crime shows at lunch the other day, and we agreed while it's fun to rubbish the impossible technological feats that their boffins can perform, we envy the soundtracks they have while they're doing it. We need a soundtrack to space science!
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[User Picture]From: nanila
2010-08-30 22:04 (UTC)
I'm going to test this tomorrow, while I'm calibrating.
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[User Picture]From: nanila
2010-08-27 09:41 (UTC)
Sure, I'll do my best to answer!
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[User Picture]From: feylike
2010-08-27 04:33 (UTC)
awesome! and i appreciate that it's really sparse data; the red splodge looks only one pixel wide in the plot, so it represents only a few minutes of data? an odd feature i'm curious about is what looks like a faint (slightly fainter than the second harmonic of the spin tone) slow, slightly wiggly frequency modulation that goes up from 0.4Hz early on 12/10 to almost 1Hz at the start of the sudden increase in signal, then goes down after the wide black band. (it might be a second harmonic of something, but if so, i don't see the fundamental on the right hand side.)
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[User Picture]From: nanila
2010-08-27 09:44 (UTC)
Yes, there's less than 20 minutes of data in Range 7 in most orbits. I think the wiggly modulation you're talking about is actual science - a low frequency mirror mode in the magnetosheath. The wide black band, btw, is probably a short eclipse.
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