Here is an update on where we are on extractions.
We were extracting in Houston the week before last, and progress was very slow-we had to abort two overnight extractions because of problems with the needle wandering and in both cases endangering the targets. This was mysterious behavior, and we were quite puzzled about it. We only just understood the cause of this on Thursday–it is because of large temperature varations (around 10 degrees F) in the Cosmic Dust Lab. This causes differential contraction in the extraction equipment–we don’t know yet whether it is in the micromanipulator, the long arm, the arm holder, or a combination–but it is just not acceptable to put the samples at risk. The temperature variations are new, without a doubt, but we didn’t know whether this is because it is become summer in Houston or because of some failure in the laboratory temperature control, or something else entirely. We found out this week that it was the “something else entirely”: it was a combination of a failure of the steam heating system, and also setting the thermostat lower in the neighboring Meteorite Lab, where they were processing frozen meteorites from Antarctica.
We had planned to go back this week to continue, but we postponed in order to give JSC time to diagnose and correct the problem–which they did! Zack is going back to Houston next week, and we will resume extractions. Dave is taking a well-deserved break, and will be moving to Houston permanently in June.
Here’s where we are:
38843 First IS candidate–looks consistent with a IS track when viewed in the picokeystone. Waiting for analysis from ESRF.
48469 Successfully extracted in a picokeystone, analyzed at the ALS by STXM, turned out to be a small disk-like piece of alumina
16490 Aborted in the middle of the extraction because it became clear that it was an inclusion. It looked like an extended feature in a little “valley” in a region of complex topography, but after we started the extraction and some aerogel debris was generated by the cutting, we realized that there was a substantial amount of water-clear aerogel above it, so it became clear that it was not a track. The aerogel is totally invisible in the VM and in the microscope before extraction.
834150 Successfully extracted–will go to the nanoprobe at ESRF in June
129070 This target was reminiscent of 38843. Aborted in the middle because it became obvious that it was not a track–it moved!
We have chosen another target similar to 38843, now officially named “Nairbus” by its discoverer. This is 134954. We are about half-way through its extraction, and will resume on
Tuesday just after the holiday.