Microscopy in space   Leave a comment

After the requisite “building bombs” part of my (and any self-respecting physicist’s) career, I moved into outer space- NASA. This was an *amazing* experience- to paraphrase one of my mentors, NASA is when I ‘took the blinders off’. I worked on projects that were at the boundaries of Physics and Chemistry, learned from world-class engineers and technicians how to take delicate instrumentation apart and re-assemble it *better* that it had been, and got to ride on one of the KC-135 ‘vomit comets‘ a bunch of times before it was retired.

NASA Glenn Research Center had just announced a large project- construction of 3 ‘racks’, each full of scientific equipment, was to begin. I came on board just as the ‘themes’ of the racks were being decided. I worked on the rack next to the guy in the image above- and specifically, that thing inside it.

The “fluids and combustion facility” (all three racks) consisted of the ‘combustion instrumentation rack’ (the rack with the round thing inside), the ‘fluids instrumentation rack’- the one I was involved with- and the ‘shared instrumentation rack’, the middle one. Originally, it was conceived that each rack would host about 15 experiments using common tools. For example, nearly all 15 fluids experiments used a camera. So, NASA would fly a camera that all 15 experiments would use- this was a radical concept, because until now, the scientist in charge of an experiment got final say over all scientific instrumentation needed to carry out the experiment. With the rack idea, there was a closet full of parts that an experimenter could use, thus reducing the weight and size of the experimenter’s apparatus, resulting in a financial savings for NASA (and the government). Sounds great!

Except, everyone’s experiment is different, and requires *very* different types of instrumentation. What this meant was, for example, that even if NASA provided the absolute best, top-of-the-line
camera for all 15 teams to use, at maybe 5 would use the camera.

This resulted in a lot of meetings involving angry people.

In the end, it got sorted out and instead of the fluids integrated rack hosting 15 experiments, it would host 4 (“the initial experiments”) all housed in a microscope. The experiments were:
Constrained Vapor Bubble (Pete Wayner, RPI)
Physics of Colloids in Space -2 (David Weitz, Harvard)
Physics of Hard Spheres Experiment -2 (Paul Chaikin, Princeton (now NYU))
Low Volume Fraction Entropically Driven Colloidal Assembly (Arjun Yodh, Penn)

Constrained Vapor Bubble was an experiment to study wetting. Specifically, a partially full tube of pentane would be heated on one end. The hot pentane would vaporize, the vapor would condense at the cold end, and thus heat would be carried along with the vaporized pentane. So on one hand, it’s a heat transfer experiment (understanding how efficient the process is, for example), but since the experiment involves a thin evaporating fluid film, wetting occurs as the liquid pentane flows back to the hot end. We used the microscope to image the evaporating film using interferometry, and from the images we measured the film thickness as a function of time.

The other three experiments all used hard-sphere colloids as a model system to understand various aspects of condensed matter: crystallization kinetics, crystal dislocation dynamics, the origin of stress-strain behavior, etc. The main application (at the time) was ‘photonic crystals’- colloidal crystals are sometimes called ‘artificial opal’. The PI teams generously sent us samples to test out the microscope, and those were a lot of fun to play with- we took pictures of one, and it was the featured ‘after image’ in Volume 13, issue 1 of “Optics and Photonics News”.

Our job, the contractor’s job, was to build a microscope that would perform all those experiments such that the PI only needed to supply a small (about 1 cubic foot) box with their samples. The microscope (the Light Microscopy Module) would perform all of the imaging and sample manipulation and the rack would provide all the electricity, cooling, and data storage.

Our goal was ambitious- the microscope would have, in addition to all the usual capabilities (lamps, phase contrast, DIC, darkfield, various magnifications, etc), but also have: a confocal unit, laser tweezers, static and dynamic light scattering, sample heating, sample mixing, and be completely motorized. It was designed to work without human intervention: completely automated, including alignment.

There was about 50 of us on the technical team: a small army of optical, mechanical, electrical, thermal, computer, and control engineers and a small cadre of electrical and mechanical technicians. In addition, there were the PI teams (the PI plus 4-5 postdocs and grad students for each project), the NASA technical team (4 ‘project scientists’) and a gajillion managers- both contractor and NASA managers.

We did some amazing work- I personally tore down a modern full-featured motorized microscope down to the gears and built it back together. We flew on the KC-135 ‘vomit comet’ to test out preliminary designs of the immersion oil injector to see if the oil would wet the glass and stay put without gravity. We took an instrument that would normally be the size of a large refrigerator and shrunk it down to the size of a microwave oven. Working with the PI teams- learning the science and working with them to deliver an instrument that would meet or exceed their own laboratory capabilities was a privileged experience.

NASA is where I learned to ‘think outside the box’- finding solutions to our problems meant looking in strange places- not recognizing any boundaries. There’s also benefit in being able to call someone on the phone and say “I’m with NASA”. *Everyone* returned my calls- the only person who didn’t was a Nobel Prize winner.

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Posted March 18, 2011 by resnicklab

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