Cheers to Dr. Zaman!

 Although the lab has of course graduated many a student over the years. This May was the graduation of my very first grad student. On the auspicious day of April 1, Mahi successfully defended his thesis. In addition to Sean, Meredith and I, Colin Meyers (Dartmouth) and Geoff Collins (Wheaton College) were on his committee (Geoff in person, Colin zooming in). He did an excellent job both in describing his dissertation to an audience with various backgrounds, but also on defending the science questions we had. 

We had a party back in the lab's conference room, where he got to don and sign the official DEES gown...

Mahi had many of his friends and family in attendance, with more family members zooming in.

Cheers to Dr. Zaman!

And a few months later we were able to celebrate again formally. It was my first time walking in the parade of faculty and it was a big honor to be allowed to hood Mahi in the official ceremony. 

Ted Retirement Party

 After a long and exciting career with us, Ted is retiring. We threw a small barbecue going away party for him, inviting many of the people at Lamont (or retired) that have worked alongside Ted through the years. 

A case of rolling rocks (historical drink of the lab) was donated by Chris Marone.

A round of shots may or may not have been consumed while I was away at a meeting.

Even the geese (who are fed regularly by Ted) came by to give their regards.

And Hatsuki arranged this amazing tribute, getting input and old photos from loads of people from over the years. 

Open House 2024!

 This year we did a few new things at the annual Open House. There was a collection of Lunar samples and meteorites visiting us from the Natural History Museum, so they asked for some us to be inside Comer to talk about rocks and minerals. Abhishek and I took turns describing this modest collection of rock types.

It was fun to talk about Igneous, Metamorphic, and Sedimentary rocks. I also tried to sneak in some info about Europa and the Clipper mission (which had just launched the week before) whenever I could. 

Meanwhile out in the tent, we had our usual collection of earthquake related exhibits.  Also I upped my game this year and instead of just the subduction cake, I went all in and made a cake for each plate boundary: divergent, convergent, and transform.

In general I would say that the cakes were a big hit. But I'll admit that it's hard to keep their focus on the science and plate tectonics when their eyes and minds are going "cake, cake, cake, when is she going to give me the cake".

Open House 2023

Despite the rain, we had yet another great Open House at Lamont this year. Here are some shots from the day.

Here Jake talks about the mechanics of an earthquake with our slider block set up.

Shradha takes over later in the day. She only just arrived with our group and she jumped in after hearing Jake's spiel just once and handled the crowds like a pro.

Hatsuki explains the process of liquefaction during an earthquake at our little shaky table.

High School intern Vincent takes over on the shaky table later in the day and also does a great job.

Charlotte explains elasticity and strain gauges to a man very prepared for the weather.

And finally Nick teaches about plate tectonics and plate boundaries behind my subduction zone cake.

Summer 2023 in the lab

 Some highlights from the lab this summer. We had a crew of three high school interns: Vincent, Maya, and Sam. Vincent was exploring ice sliding on different rock types. Maya used active acoustics to characterize two ice interfaces at different normal stress. Sam used bench top test of carbon mineralization while looking at the effect of stress and pH. They were a great crew!

During this summer we also had a visitor from New Zealand, Lucy, who brought with her some samples from Dave Prior's lab. Lucy was here to learn about attenuation and Hatsuki's new apparatus. We decided to hold a mini-workshop about Q and invited folks from nearby U.Penn.

I can't remember why it was that Travis brought his dewar, but I realized that between his, Lucy's and ours (which Kris was loading up and getting ready to take to the UK), we had an outright gaggle of dewars.

Introducing "PinQ": our new cryogenic forced oscillation apparatus

 With our funding of a study on the dislocation and strain dependence of attenuation (also called inverse Q) and the arrival of Dr. Hatsuki Yamauchi to work on the project, we decided to assess our machine capabilities. It became quite clear that our original idea of using the biax would not be a good idea because it is not stiff enough (which is part of why it is a great friction apparatus). So we needed to create a new apparatus. Yamauchi-san and I had both worked on a great apparatus in Japan, that had high strain resolution and very precise application of stress. That apparatus ran at room temperature or slightly higher temperatures. So we needed to adapt that design (the "TKY-style" apparatus) for cold temperature work. 

2021 and 2022 were bad times for purchasing parts and it seemed every component was on back order and seriously delayed. The machinist also had a back log. Whatever could be done by us, we did.

First big task was to find a nice stiff, hopefully pre-existing, frame. Ted found one (as he does) but it was looking very dirty and not the right color at all. Hatsuki suggested a paint job and new color scheme. And thus the frame was painted a bright beautiful shade of pink.

Eventually the laser displacements meters (and their stage motors), the screw jack, the stepper motor, the piezo-electric actuator and the rotational base all arrived and Hatsuki assembled it all on the stone table Ted had acquired from somewhere.

Copper coils connected to circulating fluid created the cryostat, with a bellows at the top to prevent condensation but not affect the sample testing. The only thing that it needed now was a brain.

This is when we scheduled John Leeman of Leeman Geophysical to come out. Over the course of a few day visit he got us all set up with a LabView control system that would drive the multi-day experiments, monitor temperatures and all other feedbacks, and record the calibrated data.

We then installed a shelf to hold all the control boxes, etc. Here is the resulting set up.

In the Review of Scientific Instruments paper that followed, Dr. Yamauchi provided all of the error corrections and calibrations and describes the working range of the apparatus. Many exciting papers to follow!

 

Tether testing with Vishaal

As part of our NASA-funded STI project, Vishaal came back out again for another few months in the lab. Covid prevented him from coming in the summer, but he was able to spend the fall with us. After successful runs at relatively warm temperature last summer, we were ready to start going colder.  Or so we thought...  

Upon closer inspection we realized the pump in our custom circulating fluid chiller was leaking. After taking it completely apart (a pretty big feat in itself) we found that some seals were cracked and a spring broken. A bit of delay, but hey, now we know how to replace a seal on a pump. Always good to acquire some real world skills.

While we were at it, we decided to do some reorganization so that the chiller flow control valves were attached to the back wall and not hanging off the front of the rig. RTDs were installed to monitor temperature along the fluid path.

We also worked with colleagues at WHOI on a die that allows pretensioning of the tether before freezing the ice around it. Our addition was to add tubing and valves to pull a vacuum on ice samples and flood from the bottom. The final sample assembly is one long bar that fits into the cryostat. The notched square tube allows us to load the assembly without touching the ice. 

An optical meter measures signal loss during shearing of the tethers. Vishaal splices the ends of the tether. 

Here is the whole set up in the new lab. Ain't it pretty?

During Vishaal's last week we decided to push the envelope and go all the way down to Europa surface temperatures (~100K). For this, we took the chiller out of the system and instead went to directly pumping liquid nitrogen into the cryostat. First we pre-chilled by pouring LN all over everything.

Ideally we pump only enough LN to cool the cryostat and it comes out as a gas. But occasionally the LN just poured right through....

It was frosty in there!!  But we held 100K steady for the whole test. A great end to a successful series of experiments!