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July 6, 2019 - The Adventure Begins

Six months ago I packed up whatever I could fit into my Toyota pickup and headed east from Seattle, out across the winter landscape...

Driving to Minnesota -25 degrees Fahrenheit is pretty cold. At -25°F, it turns out, transmission fluid starts to freeze. I'm in my pickup at a hotel in Sioux Falls, and it is -25°F outside. The manual transmission is stuck in first gear, where it was left the night before when it was parked. The seats are frozen hard as rock. But, the battery I purchased three days prior in preparation for the cold Midwest winter was up to the task. The engine turns over... It takes a few seconds, but it sputters and rumbles to life, running very rough and accompanied by clanking, grinding and squealing sounds that are definitely not good. A little pressure on the gas pedal and it smooths out, but still sounds like death. Slowly, excruciatingly slowly, the sounds return to normal. After holding in the clutch for 30 minutes inside the frozen cab, the engine has warmed up the transmission enough to get out of first gear, and I'm mobile again! Not everyone in the parking lot that morning was so lucky. This 'polar vortex' is by far the coldest weather I've ever experienced. It's not too bad, as long as you bundle up well. I can deal with this. And that's good, because where I'm going this November, -25F is just the beginning...

...three days later I found myself building a telescope in a lab at the University of Minnesota. I left an exciting job working with great people making more money. I am living apart from my friends, family, fiancée and dog. I left all that (for now) because this particular telescope will be deployed to the South Pole.

And I get to spend an entire year there.



July 13, 2019 - So What Am I Doing in Minnesota?

I'm an aerospace engineer. I worked at a wind tunnel and in flight testing. So how did I end up at a cosmology lab working on a telescope? Well, there is a lot of engineering that goes into building a telescope. And it turns out my operational experience in a wind tunnel test lab and in flight testing makes me well suited to the job of being the first "winterover engineer" for the BICEP Array telescope.

BICEP Array telescope mount at UMN during assembly
BICEP Array telescope mount at UMN during assembly

I started in early February to help the team here during the final 9 months of telescope construction before it is shipped to the South Pole. There has been a lot to do, small pieces of the system that are still left to design and build, and lots of testing before deployment. Things are coming together rapidly now.

The telescope needs to be ready in September to make its long voyage to the South Pole. It will go in pieces by truck to San Diego, then board a navy ship to be transported to Christchurch, NZ, where it will be loaded onto a C17 cargo plane and flown to McMurdo, a coastal base on Antarctica. Finally, the telescope will be transferred to a smaller LC130 cargo plane, the largest aircraft that is capable of landing on the South Pole skiway. A group of about 15 of us from the BICEP collaboration (including University of Minnesota, Caltech, Stanford, Harvard, and others) will meet the telescope at the south pole and spend the Antarctic summer putting it all together. The size of the team will taper toward the end of the season, down to just one person (that's me!). Around February, the last airplane until the following November will depart, leaving the station isolated for about 9 months. At that point, it will be me and the same ~40 people living at the station until the next summer. It is a mixed group of station support staff and scientists working on other experiments.

The operation, care, and maintenance of the telescope for the winter will be my responsibility. Every day I will walk a kilometer from the station out to the telescope under the night sky. I'm excited for the challenge, for the sheer absurdity of where I'll be living, and for the experience of sharing a winter with a small isolated community. I'm super lucky to have the opportunity, and especially lucky to have people in my life who are supportive of my decision to go on this crazy adventure (thanks Danielle!).



July 20, 2019 - The Science!

The BICEP Array telescope is a microwave frequency telescope, peering back in time at the oldest light in the universe. The farther away an object is, the more its light is red-shifted, or stretched to a longer wavelength (lower frequency) of light. The mind-bending simple explanation for this fact is that space itself is actually expanding, stretching the light traveling through it.

After the big bang, the universe was extremely dense and hot, and only elementary particles existed. The universe slowed its expansion, cooled, and the particles coalesced into protons. Light at this time wasn't able to travel far before being scattered by the plasma. The universe was a dense, opaque fog. But the universe expanded and cooled enough so that the electrons and protons could combine into Helium. The Helium gas, and thus also, finally, the universe, was transparent, allowing light to spread through the universe unimpeded. This is known as the time of last scattering, some 380,000 years after the big bang. That ancient light is still traveling through our universe today, 13.8 billion years later, and is known as the cosmic microwave background (CMB).

This is the oldest light from the most distant source in the universe, and has been stretched to millimeter-scale wavelengths. Being the oldest light, it gives us a glimpse of the universe in it's very early stages. The CMB is almost uniform in all directions, except for very subtle variations. The uniformity of the light can be accounted for by a period of very rapid expansion of the universe right after the big bang, called inflation. This stretched out space and everything in it so fast and so much that now we see a smooth, almost featureless CMB. The very subtle variations in intensity of the CMB indicates to us the non-uniform distribution of matter in the early universe. It is from these non-uniformities that large-scale structure of the universe formed (think galaxies and clusters of galaxies!).

History of the Universe
History of the Universe (BICEP2 collaboration)

Inflation and the big bang sounds crazy, but it is the most straightforward explanation for what scientists have observed. The problem is, we can't see light older than the CMB, because back then the universe was opaque. So how can we find out if the big bang and inflation are real if we can't see it?

During inflation, the rapid expansion of the universe outpaced the speed of light, sending ripples through the fabric of spacetime. These ripples are known as gravitational waves. The existence of gravitational waves were predicted by the famous theory of general relativity over 100 years ago, and the first gravitational waves ever detected were finally measured by the LIGO experiment on September 14, 2015, from two merging black holes. What a time to be alive!

Check out this video about a confirmed detection of gravitational waves, from one of my favorite science youtube channels.

As the light of the CMB was generated in the presence of the gravitational waves still echoing through the universe since their genesis during inflation, it was polarized with a combination of patterns known as 'E-Mode' and 'B-Mode' polarization. E-modes can be produced by light created in the presence of gravitational waves, as well as by the uneven distribution of matter and energy (in an effect called Thomson scattering). B-modes were only produced by the gravitational waves at the time of last scattering. The relative strength of the measured B-modes to E-modes can tell us about the behavior of the early evolution of the universe, and providing another data point constraining the standard cosmological model scientists use to describe it.

BICEP2 telescope B-Mode signal
BICEP2 telescope B-Mode signal (BICEP2 collaboration)

Another problem is that, in the modern universe, the CMB is not the only source of 'B-Mode' polarization. It can also be produced by the scattering of light by dust particles, drifting through the magnetic field lines that twist and turn through our own galaxy. The spectra of the interstellar dust and CMB are known to be different, so by observing the same area of sky at different frequencies it is possible to differentiate between the two sources of polarized light. There is still uncertainty in the relative contributions of each source in our measurements, and being able to carefully extract the signal from only the CMB is a primary goal of the BICEP Array telescope. The telescope will have higher sensitivity at more frequencies than the CMB polarization telescopes that come before it. The data we collect will help refine our understanding of the evolution of the early universe!