photo courtesy NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute; The “heart feature”:  Scientists theorize that  accumulated ice (likely  frozen nitrogen) from Pluto's uplands (right side of this image) warms and flows from the planet’s peaks onto Sputnik Planum through the valleys indicated by the red arrows (above). Photo scale width: 390 miles

Cold Science

Written by Tom Marcinko Category: Valley News Issue: March 2016
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Arizona scientists are growing a little slice of Pluto, right in the dwarf planet’s “hometown” of Flagstaff.

“This is sort of like the crime lab where you’ve got all the suspects in the database,” says Dr. Stephen Tegler, chair of NAU’s Physics & Astronomy Department. He’s pointing to a tabletop-sprawling gadget that looks like a Maker Faire espresso machine/food processor. Custom-built by professors and students over a dozen years, the $1 million Astrophysical Ice Laboratory is a tool to investigate Pluto and other billions-miles-distant real estate – all without needing to leave Flagstaff, though the lab’s services are in demand by scientists worldwide.

In this case, the “suspects” are frozen gases, and the “crime scene” the distant reaches of the solar system. Tegler and colleagues created the ice lab out of necessity– specifically, the need to cool methane, nitrogen and carbon monoxide down to -400 Fahrenheit. When gases get that cold, they change states and freeze solid, or sometimes condense into liquids. Tegler’s team uses the lab to make Pluto-like ice for scientists at NAU, Lowell Observatory, and other locations to study. They compare and contrast the locally-sourced ingredients with images and data beamed back from NASA’s New Horizons’ space probe, which zipped past Pluto last July.

The lab simulates the many different kinds of ice detected in the eye-opening snapshots of Pluto and one of its moons, Charon, taken by the spacecraft’s instruments. The research could help explain the origin of life in the solar system, and maybe even yield insights into the changing climate on planet Earth.

In the lab, Tegler and company shine visible or infrared light on the very thin layers of newly-created ice to take “fingerprints” on a microscopic scale. “Every molecule has a different pattern,” Tegler explains. Not only that, but the fingerprints change with pressure, temperature and the addition of other molecules. Tegler’s team can tweak the icy IDs on demand, to compare lab-grown cold stuff with incoming Pluto data from New Horizons.

Over the decades, ground-based peeks at Pluto have allowed for “obscure and abstract” studies, says Oliver White, a planetary scientist at the NASA Ames Research Center in Moffett Field, Calif. But since New Horizons, “What Pluto has provided us with is an actual laboratory. What we get out of the ice lab is experimentation that is more focused and thorough... [It can] help us understand what scenarios are feasible for the very strange suite of landforms we see on Pluto.”

MIT planetary science grad student Alissa Earle is using New Horizons and ice-lab data to study the boundaries of Pluto’s now-famous “heart” feature. The outskirts of the heart show signs of pitted ice and also of warmer ice rising to the surface, like blobs in a lava lamp. “This is just one of the regions where results from the NAU ice lab can really help us better understand what is going on... The work done in the lab helps us better understand how these substances behave at Pluto temperatures and pressures, which in turn helps us understand what we are seeing in the images being sent back by New Horizons.”

And there’s plenty yet to understand, says Lowell astronomer Will Grundy, who as co-investigator of NASA’s New Horizons team had input into designing the mission. Scientists have known the nature of Pluto’s composition for decades, but New Horizons showed how the stuff on the little world’s surface interacts to build mountains and dig valleys. “[It’s] wild speculation until you see it laid out on a scale of tens of kilometers,” Grundy says.

New Horizons’ next destination could well keep the ice lab busy, too. On New Year’s Day of 2019, it will sail by a 30-mile-wide object called (for now) 2014-MU69, one of “zillions” (Grundy’s word) of mysterious objects in the zone of debris known as the Kuiper belt. Almost nothing is known about Kuiper objects, starting with whether they might be round, disk-shaped or a blackberry-like clump. “I haven’t the faintest idea what to expect,” Grundy says. “We don’t even know what kind of hypothesis to make.”

Whatever New Horizons finds, it will probably include more jobs for the ice lab, and draw more science students to Arizona. Lowell Observatory, where Pluto was discovered in 1930, counts 80,000 visitors a year, and had standing-room-only the day of New Horizons’ flyby. Tegler also cites ASU, the University of Arizona, the US Geological Survey, and the US Naval Observatory as other reasons Arizona is “a great place to do astronomy.”

And a great place to make custom “alien ice,” too.


Cosmic Cocktail