Meet Armando

Armando Domingos worked on his senior thesis this year in the rock and ice mechanics lab.

In addition to helping me immensely with making ice samples for frictional testing, he also made his own "exotic ice" samples by mixing in small amounts of ammonia. Ammonia is considered a possible second phase on Enceladus and is particularly interesting because of its deep eutectic with ice.

In particular he was looking at the equilibrium microstructure of the ice+ammonia system above the solidus, so where the ammonia was in a melt phase. Based on the relative surface energies, a partial melt system will have melt located at triple junctions in the ice in either trapped convex blebs, concave pockets, or completely wetted grain faces. The measure of the wetting angle is called the "dihedral angle".

Armando made dozens of samples and measured several hundred angles and wrote it all up in his senior thesis. He is now heading off to grad school at U.C. Berkeley. Best of luck, Armando!

Columbia Alumni Cruise Lecture

This spring I was given the amazing opportunity to travel with the Columbia Alumni Travel group on a cruise of the Sea of Japan. I joined nine Columbia Alums and almost 200 other Alumni travelers on a 10-day excursion of some of the classic sights of Japan (plus one stop in South Korea).

 After a couple of days in Kyoto, we boarded the Ponant cruise line's ship, L'Austral.

Some of the amazing things we saw were the golden pavilion (kinkakuji)...

 Himeji castle (which was under renovation the entire time I lived in Japan, so this was a big treat)...

 ...and the floating torii at Miyajima.

My real purpose for being there, however, was to provide lectures for the travelers. About five other lecturers and I provided an educational backdrop to the cruise, giving one-hour lectures in our areas of expertise while the ship was at sea.

My fellow lecturers were historians and art historians, so I was the sole scientist in the group. I gave two lectures: "Japan and the Ring of Fire", which was an overview of the volcanism and seismic history of the region, including my first hand account of the Tohoku earthquake; and "Earthquakes: Friend or Foe?" (spoiler alert: it's foe, but I discussed how we can use the tiny ones occurring every day all around the earth to our benefit via seismic methods) which took a long tangent into icy satellites. I'm told the first talk was a big hit, very accessible, lots of fun, but the second was a bit "out there". Oh well, you win some, you lose some. Overall it was an amazing trip. Ready to join in on the next alumni lecture series if ever I am asked again (hint hint).

Hanami 2017

The weather actually cooperated this year for our annual hanami party. In previous years we were not so lucky. We spread out our blue tarp and shared our treats under the bloom of the cherry blossom trees.

Cryostat 2.0

Our original cryostat for the friction rig was awesome. We made lots of improvements to the way that temperature is monitored (with RTDs now, which have much less error) and in the insulation, etc. We started using a protocol of placing the rocks and metal at the desired testing temperature in a chest freezer over night before we start an experiment. So we've got it to where we can load a sample, give it an hour or two to really level out to a steady temperature, and then we can just let it run for hours to days of testing at constant T. Using that cryostat, we ran our first series of experiments on the temperature dependence of ice on rock friction, which was written up in this paper.

However, the lowest temperature it could achieve was about -20 deg C, determined by the chiller that circulates methanol+water through cooling blocks on the side of the cryostat. That's completely fine for terrestrial applications, but we want to also test planetary ice. So we need to go colder. Much much colder! That's why Mike has begun working on Cryostat 2.0. This cryostat will instead use methanol cooled by liquid nitrogen to flow through copper coils directly adjacent to the sample. The plus-shaped sample housing sits on top of stiff, insulating material. 

It sits inside a box that will be insulated by creating a vacuum. More to come!

Lab Field Trip 2016