University of Minnesota
School of Physics & Astronomy


Telescope taking shape in Physics High Bay

Open House at Physics and Nanobuilding High Bay showing off the telescope build in progress.
Michael Crumrine

Twenty two tons of precision welded steel are coming together in the Physics and Nanotechnology building high bay to form the BICEP Array telescope that will be deployed to the South Pole at the end of 2019. The pieces of the telescope began arriving last September and since then, Professor Clem Pryke and his group have been busy working to put them together.

Pryke has been working for twenty years, building a succession of observatories at the south pole in his search for evidence of the Inflationary period that may have preceded the Big Bang. “We’re looking for a gravitational wave signal, which comes from the beginning of the Universe, at the beginning of time,” Pryke said.
The inflation theory makes a specific prediction that should be observable in the polarization pattern of the cosmic microwave background. “We can think of the CMB as the afterglow from the big bang,” he said. The gravitational waves the group is looking for are the same phenomenon that LIGO detected, but the source for them is very, very different. LIGO is looking at gravitational waves from colliding black holes and neutron stars a few billion years ago. Pryke’s group is looking for gravitational waves originating 14 billion years ago at the very beginning of the Universe. “The signature we’re looking for is called B Modes. It’s a pattern of sticks, and if the sticks are arranged in a swirl, that’s a B-mode.“

Finding this tell tale pattern has driven Pryke and his team to the South Pole to assemble a series of telescopes specifically designed to find B modes. The new telescope is the next generation in a sequence of experiments with a similar goal and similar technology. “I think it’s interesting that there is no way one could talk about building an experiment on this scale if it wasn’t a successor in a sequence. So it’s only because we’ve done this before and we can scale it up. Otherwise it would just be crazy and it wouldn’t work starting from zero.”

When asked why LIGO couldn’t detect this pattern, he said that it would need to be built on the scale of our solar system and involve multiple spacecraft shooting megawatt lasers the distance of the Earth’s orbit around the sun. “People have speculated about such an experiment, but it’s not going to happen in this century.”

Building a Bigger Machine

This generation of telescope is bigger and better than those built previously by Pryke and his team. It will cover a wider range of frequencies. It will map more sky faster to higher sensitivity. “These experiments are all sensitivity limited and the only way to get more sensitivity is to build a bigger machine.”

Getting the “bigger machine” to South Pole is a long and complicated journey. The life of the telescope from the start of design to the end of it’s five year run will be ten years. The steel framework of the telescope was fabricated by a firm outside of Milan, Italy and then shipped to New York by cargo ship. From there it went by rail to Minneapolis where it was loaded onto trucks to travel the last few miles to the Physics and Nanotechnology building on the University of Minnesota’s East Bank. The group finished assembling the frame, then added in the motor controls needed to move the telescope around. They are now in the process of installation of the first of four receivers, which will do the actual observing. This summer Minnesota will host physicists from Harvard, Stanford and Caltech who will work on the receiver installation and testing. After that, the telescope needs to be insulated from the harsh South Polar environment before it is disassembled, loaded back on trucks and hauled to California. From there it will be shipped to New Zealand and then flown first to McMurdo station on the coast of Antarctica then to the South Pole station. It will be installed in the austral summer (late 2019, early 2020) with the plan to begin operation in February, 2020.

Only one or two of the four receivers will be install this year. The other two or three will be installed the following season the 2020-2021 Season. “We go every year but it will be a super big year because we’ve got a whole new platform.”

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