Hope for the Telescope

Last Friday was my last day in the lab, and over the past week I’ve been thinking a lot about the experience I had and what it means for me going forwards. The last day I spent in the lab was similar to Thursday. Simon and I worked on a second cold load to measure the detector response using alcohol, liquid nitrogen, and dry ice.

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I was able to run the program to start the detector response curve this time, and I could see the graph move as Simon slid the lid under the box. As we looked at the graphs, Simon and I talked about the future of the project.

“Will you still get a picture, even if it’s running .1 milliKelvin over what you were expecting?”I asked.

“We’ll definitely get a picture.” said Simon. “It’s just a matter of how detailed it is. Keep in mind, this is the one of the highest resolution telescopes of this kind that’s ever been made. We’ll still get to see the skies. And it’s looking good for the telescope. We know what’s wrong, and hopefully by opening up the cryostat, we’ll be able to fix it. It will set us back by a few days, but we think we can fix the temperature. There is hope for this telescope to work the way we wanted!”

This was good news for me. I couldn’t even imagine the frustration I would feel if I had worked on such an expensive and difficult project for so long just for it to fail. But the hope Simon was feeling and the determination he had to make the project made me confident they would find a way to fix their problem.

After spending a week in a lab, I have a better idea of what it means to be an astrophysics. Sara described that there’s a lot of small-scale work and programming work to get to the big stuff (looking at the galaxies). This was something I never thought of, and it’s a good thing to know going forwards if I want to do this kind of work. Sara also said there’s a more theoretical side to astrophysics, one where theories are developed and ideas are thought up. It seems that it’s possible to do a multitude of things in this field. Although sometimes working in the lab was difficult and tedious, with lots of tests being run and lots of data to sift through, I can only imagine what it leads to. Doing the tedious work is worth it to look up into the sky and through time to the beginning of our universe. Spending a few weeks, a few months, a few years working on a telescope may seem boring, but it’s worth it to look up at the stars and to start to understand how we got here.

A Cloud of Liquid Nitrogen

Have you ever seen liquid nitrogen stream through a metal tube out of a pressurized canister, only to freeze the particles in the air until it looks like the whole tube has been in a blizzard? I have, and it is awesome!

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After running a few more tests yesterday to check the sensitivity of the detectors, today it was time to run a cold load to see how they were responding to heat. As soon as I walked in, Simon showed me a box he was constructing out of building foam and hot glue. I helped him add legs so it could stand on top of the cryostat, duct taped it together, and lined with with transparent plastic it wouldn’t block the waves they were trying to detect. A paper lining was added to absorb the thermal shock the box would receive when the liquid nitrogen was poured in, and we were ready to cool down the absorber inside to test the sensitivity of the detectors!

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We put on lab coats and gloves in order to pour the liquid nitrogen safely, and went to work pouring enough so it wouldn’t evaporate (nitrogen evaporates at a VERY low temperature). Once there was enough in the cold load, I looked inside. It was room temperature and the nitrogen was boiling and evaporating into gas!


Sorry for the short video — for anyone who is curious, the noise is the helium pumps working to cool down the array with the detectors.

Simon slid a higher temperature under the cold load and then took it out again and we noted the changes in the graph of what the detectors were “seeing” in terms of temperature. I don’t have a picture of the graph, but there were definitely changes when the hotter object was moved around.

After doing a few tests with the liquid nitrogen cold load, we added liquid alcohol we had gotten from the chemistry department to make another temperature load. The alcohol caused the liquid nitrogen to evaporate and tiny bubbles of frozen alcohol (also an extremely low freezing point) formed inside the box.


A few more tests were run, and I had seen my first cold load with temperature sensitivity data in action!

They’re Hanging WHAT from a Balloon?

Telescopes that search the skies for wavelengths that are too delicate to pass through our atmosphere have to be hoisted up into the air with a giant balloon. The telescopes are mainly made out of metal, so to keep one airborne, balloons the size of football stadiums or bigger are needed. You heard that right: not a football field — a football stadium. BLAST is a telescope I worked with today which will use this balloon mechanism when it observes the universe around us. Today I met with two students who are building the telescope, complete with reaction wheels and motors to allow the telescope to turn and state of the art optics mechanisms to filter light. The frame is about the size of a minivan, and is made of white metal pipes which will hold a larger metal frame, a carbon fiber mirror, and a gigantic cryostat filled with liquid helium, cooled down to below its boiling point near absolute zero. Nate, a graduate student, explained the mechanisms to me as I walked around in wonder. The sheer number of things that had to go exactly right for all the data to be collected and all the systems to function properly was mind-boggling. In addition, most of the equipment needed is not built commercially, so the graduate students have to build it all themselves.

Imagine building a machine including liquid helium, pulse pumps, and yards of spiderweb-thin wire to make a machine that cools down an array of specially designed chips to feed out into a complex computer system you have to code yourself. Doesn’t sound so easy! But this is what the students must do. They are motivated by their desire to search the skies, and I can feel it too, even through the frustration Sara and Simon feel as they sift through mountains of data and run endless tests in order to find the problem with their machine.

Since yesterday, the array in the cryostat was running a little colder — a good sign after the 1o0 milliKelvin discrepancy of the day before. However, the gap wasn’t big enough, and the graphs the computer kept outputting from the complicated programming tests Sara was running were not looking like the uniform, smooth curves she was looking for. I cannot begin to understand how they kept themselves so calm, how they worked through the frustration they must have been feeling at the circumstances there had been no way to foresee. I admired their work today greatly — I can only think how discouraged and frustrated I would be in their situation. When Brian, their collaborator on the Green Bank Telescope, arrived they explained the situation to him and he sat down to work. While some tests were running, Sara also explained to me the science and concepts behind their experiment, including how changes in the Cosmic Microwave Background (leftover radiation from the Big Bang) can show us how energetic events are in the universe, and how the inflation period of the Big Bang happened in thousandths of thousandths of seconds to set the stage for cosmological formations.

Here is a picture of the CMB:
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It was incredibly interesting and complicated. It is unfathomable and crazy — the way that we can look back in time using light that is only now getting to us from the far reaches of the universe during the early stages of the universe may be the closest we ever get to time travel. But that doesn’t mean we aren’t going to try, and the UPenn lab is the perfect place to begin to unravel the mysteries of the universe.

Houston, We Have a Problem

Murphy’s Law: Anything that can go wrong, will go wrong. Brilliant people have spent years of their lives working on cutting-edge technology, and unforeseen consequences can mean much more time spent on these experiments.

Simon’s worried face was the first thing I saw when I walked into the lab today. He was staring at the cryostat, a large, green canister, which was emitting a rhythmical squeaking noise as the pumps strained to cool down the inner lenses.

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“It’s running 100 milliKelvin above where it should be right now. We’ve had it cooling for much longer than expected, and this is worrisome.”

0.1 Kelvin above where the temperature should be, within fractions of absolute zero, doesn’t seem like much of a big deal. For this project, however, it is devastating. The whole project depends on the temperature being constant and in a certain range. Without the correct temperature, the measure of heat using changes in resistance falls apart, as does the superconducting nature of the wires. Without the correct temperature, bright, energetic events in the universe would not even register.

Sara and Simon sat by the computer, looking at complicated, squiggly graphs and deciphering their secret meanings, gaining data from them when all I saw was a strange figure reminiscent of a Jackson Pollock painting. They plugged numbers into a code and the computer chugged out countless graphs. Trying to pinpoint the exact correct ways to make the cryostat function was proving to be very difficult. Hopefully, there is nothing wrong inside the cryostat itself, which would mean a few more days of work opening it back up, fixing it, closing it again, and cooling it down. As Simon and Sara work hard to fix the problem, I will be working on a balloon-borne telescope project tomorrow called BLAST — interesting stories to come on that!

Galactic Nuclei

The first thing I noticed when I walked into the lab was how loud it was. There was an intense humming coming from a large metal crate, and a ventilation that created an additional whooshing noise. I almost had to shout to be heard over the noise as I said hello to the people with whom I would be working on MUSTANG-2, a cosmological project in the department of Astrophysics at University of Pennsylvania. The people in the lab were my sponsor, Sara S., a tall, friendly, and confident graduate student, and Simon, a kind, soft-spoken researcher who visited UPenn from England and met his wife. The two were managing the huge crate of electronics, fitted with five different computers, and a gigantic, homemade cryostat (to cool materials down to within fractions of absolute zero). Sara introduced me to the general idea of the materials they were using, and then sat down to solder some pieces together on the lens of the telescope. As she worked, she told me about the goal of the project.

The types of things one would find in the UPenn Experimental Cosmology lab

“The metal crate has four different computers that output signals from our detectors to the main computer where we read the data. Our detectors are only made in a few places in the world, and we have one of the highest resolutions available, with many more pixels than most telescopes. We’re going to bring this apparatus down to a gigantic telescope in Virginia, where light will bounce off a large mirror and focus onto our lens, which will be cooled down to millionths of a Kelvin away from absolute zero. The signals will travel along the wires, which, due to their coldness, will become superconducting. The infrared rays we measure will be registered on a series of resistors, which will change in resistance rapidly with changes in temperature. Then, we can create what is essentially a heat map of galaxies in the universe in order to learn how they were formed and what they’re doing now.”

Wow.

Thanks to T. Larry’s successful efforts to control and teach my Physics 4 class, I understood at least a fraction of what Sara was trying to tell me.

“So, basically, we’re making a heat map?” I asked timidly.

“Yep!” she exclaimed with a smile. “And you get to help load the lenses into the cryostat!” A big responsibility for me, when each detector is worth thousands and the whole project has taken years of hard work. I sure didn’t want to drop anything!

While Sara continued to solder, Simon pulled one computer out of the crate, telling me it wasn’t ventilating properly. The resistance of the apparatus they had was higher than expected, which meant a higher base voltage had to be run through the circuitry in order to maintain the desired resistance, right on the edge of superconductivity. As a result, the computer and the crate were overheating, and something had to be done. We opened up the computer, which was sealed with metal tape to keep the signals from interfering with any technology, and took a look at the circuitry.

“See those parts right there?” asked Simon, pointing to a few bits of the circuit smaller than the nail on my pinky finger. “For seven months those didn’t work, until we dabbed a drop of silver paint under them. Seven months of failed work just to discover a unit the size of the head of a pin was not grounded correctly.” That floored me. I couldn’t even imagine working on something for seven months, only to realize one tiny thing was the reason I couldn’t look at the stars! Keeping the issue of grounding in mind, the problem was easily solved and the ventilation issue was resolved.

“I’m done!” said Sara when she finished soldering the central lens of the project together. She carefully carried it over to the cryostat, and I watched with bated breath, knowing it was the result of tens of thousands of dollars and years of work and research. We cleaned the parts that had to fit together with alcohol in order to create a vacuum seal, flipped the heavy cryostat over. The lens then went in the top, and had to be screwed in carefully. After Sara and I completed that, we put tape around the edges to ensure there were no light leaks hat would affect the readings. Then, three more lenses, each more delicate than the last, had to be installed, screwed in, and taped. Finally, a lid was placed on the top and screwed in to ensure a vacuum seal and no light leaks. The cryostat was loaded. We flipped it back over and admired the work. It was ready to be transported to Virginia, where it would be cooled using an isotope of Helium and then hung from the ceiling to absorb the light focused on the mirror. Then, we could look at the stars! It was incredible to be able to help install something that was state-of-the-art, something technologically advanced and important for the understanding of our universe. The theory I have learned in class on a microscopic scale was playing out in front of my eyes on a large scale, and I was able to take part in it! I could feel the excitement filling me as I looked around the room, realizing I could be a part of something like this, that I could help to explore worlds we know nothing about. I am excited when I look forwards to next week and the work I will do next, analyzing data and trying to understand the mysterious bodies that make up our universe. Stay tuned for more updates on the galactic nuclei heat map!