Piece of UW-Madison history headed to Smithsonian’s National Air and Space Museum

May 3, 2019

Hundreds of researchers from around the globe gathered at UW-Madison Thursday to send a 25-pound, spherical sensor off to the Smithsonian Institution for thousands of museum-goers to view in decades to come.

The IceCube Neutrino Observatory, an international research collaboration led by UW-Madison, buried more than 5,000 sensors beneath sheets of ice at the South Pole over a period of seven Antarctic summers that began in 2004.

The bowling ball-size sensors have led to a series of recent astronomical breakthroughs about neutrinos, high-energy particles that crisscross space at nearly the speed of light.

Researchers in 2013 announced the identification of neutrinos coming from outside the solar system for the first time. The invisible cosmic objects collide with ice, releasing a flash of blue light picked up by the sensors.

And last summer, scientists solved a century-old mystery of the origins of cosmic rays. The identification of a blazar — a technical term for a galaxy with a massive spinning black hole in its center — is suggested to be the first known cosmic source for a neutrino.

David DeVorkin, a curator at the National Air and Space Museum, requested a sensor from UW-Madison because it is “an excellent example of multimessenger astrophysics.”

“Objects we collect like this we fully intend to preserve indefinitely,” he said.

At least 200 scientists from around the world met at Union South to send off the sensor.

In the early 2000s, IceCube director of operations Kael Hanson led a team in the design of the sensors, many of which were manufactured at UW-Madison’s Physical Sciences Laboratory in Stoughton.

The sensors, about $5,500 each, must weather the extreme cold and pressure of the frozen tundra. The total cost of instruments for the Amundsen–Scott South Pole Station operation totals about $100 million, Hanson said.

Also known as digital optical modules, the sensors operate 24 hours a day, seven days a week, no matter the temperature. Only a handful have failed, he said.

Researchers deployed hot water drills to melt through mile-deep holes of ice so the sensors could be buried.

The next leap

The next stage of research for IceCube is burying more sensors to increase tenfold the amount of space able to be detected, according to IceCube lead investigator Francis Halzen.

The project, which will begin sometime after 2022, is called Gentoo, a nod to a penguin species residing on Antarctica.

“That’s as close as physicists get to a sense of humor,” Halzen joked.

Halzen has led the IceCube operation for nearly two decades, but has never visited Antarctica. He will, however, visit Washington, D.C., with his 7-year-old grandson as soon as the sensor is on public display.

“I don’t think there’s anything greater than taking my grandson to Washington and showing him this dome,” Halzen said. “He has not necessarily picked up on neutrinos, but he’s interested in science.”

Down the road

They may have to wait a few years before the sensor is on public display.

The National Air and Space Museum is planning a long-term rehabilitation of the entire museum, DeVorkin said. Officials plan to eventually place the sensor, along with other telescopes and instruments, in an “Explore the Universe” gallery showcasing “flashpoints” in the history of astronomy.

The exhibit is tentatively scheduled to debut in 2024.