U of M News Wire
January 3, 2008
U of M physicist reads the history of the solar system in grains of comet dust
By Deane Morrison
U of M News Wire
Four years ago, NASA’s Stardust spacecraft chased down a comet and collected grains of dust blowing off its nucleus. When the spacecraft Comet Wild-2 returned, comet dust was shipped to scientists all over the world, including University of Minnesota physics professor Bob Pepin. After testing helium and neon trapped in the dust specks, Pepin and his colleagues report that while the comet formed in the icy fringes of the solar system, the dust appears to have been born close to the infant sun and bombarded by intense radiation from these and other gases before being flung out beyond Neptune and trapped in the comet. The research appears in the Jan. 4 issue of the journal Science.
The finding opens the question of what was going on in the early life of the solar system to subject the dust to such intense radiation and hurl them hundreds of millions of miles from their birthplace.
The studies of cometary dust are part of a larger effort to trace the history of our celestial neighborhood.
“We want to establish what the solar system looked like in the very early stages,” said Pepin. “If we establish the starting conditions, we can tell what happened in between then and now." One early event was the birth of Earth's moon, about 50 million years after the solar system formed.
Also, the gases he studies have relevance even closer to home. “Because some scientists have proposed that comets have contributed these gases to the atmospheres of Earth, Venus and Mars, learning about them in comets would be fascinating,” he said.
Comet Wild-2 (pronounced Vilt-two) is thought to have originated in the Kuiper Belt, a comet-rich region stretching from just inside the orbit of Neptune to well beyond Pluto. As it grew in this roughly -360 F region, it incorporated grains of dust and ambient gas.
The comet received a visit from the Stardust spacecraft in early January 2004, two years after its launch. Veering as close as 149 miles to the comet nucleus, Stardust used a spongy, ultralight glass-fiber material called aerogel to trap the dust. At the moment of encounter, the spacecraft exposed a sheet of aerogel -- supported by a framework -- to the stream of particles blowing off the nucleus.
“It looked like a tennis racket,” said Pepin. “It was exposed for approximately 20 minutes.”
The aerogel trapped aggregates of fine particles that hit at 13,000 miles per hour and split on impact. The collisions left drumstick-shaped trails pointing inward from the surface of the aerogel.
After the collection, the spacecraft headed home and parachuted its payload safely back to Earth in January 2006. A few months later, Pepin received three sub-samples of particles and colleagues at Nancy University, France, received two others, all from the same particle “hit.”
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New public art on TC campus features 10-ton taconite stone from Minnesota’s Iron Range
Garden of Iron Mirrors reflects past and present
By Pauline Oo
U of M News Wire
If you’ve ever been to England, you may have made the trip to see Stonehenge -- that eyebrow-raising ring of about 30 upright stones, each more than 10 feet tall. Closer to home, on the University of Minnesota’s Twin Cities campus in Minneapolis, there is the Garden of Iron Mirrors -- a sculpture of seven massive boulders reminiscent of Stonehenge.
“There’s definitely an inspiration from ancient rock formations, Japanese and Chinese landscape design, as well as my own practice using mirrored and reflective surfaces,” says Andrea Stanislav, U of M assistant professor of sculpture, of her commissioned piece. Garden of Iron Mirrors is made up of two formations beside the renovated and recently opened Education Sciences Building -- three in the back garden overlooking the Mississippi River and four on the grassy knoll on East River Road.
Each 10-ton taconite stone from Minnesota’s Iron Range is placed the way it is for more than beauty's sake. For example, the mirror-polished stainless steel plates on some of them serve as metaphors of the building's current purpose--enlightenment and education of children--and of knowledge and learning at the University of Minnesota in general. The formation of rocks on the grassy knoll is patterned to the points of a compass: The stone facing east reflects sunrise and the one facing west reflects sunset, while the north and south rocks have polished surfaces that reveal the brownish swirls of the iron-bearing taconite inside them.
“As far as rocks go, they have been aged--these rocks are over two billion years old,” said Stanislav. “For me, [the polished surfaces] are like looking into this window of the past. Aesthetically, too, they are an echo of the river next to it ... the rocks are not just an ornamental sculpture, but a space where people could engage with each other and spend time.”
A cast iron rock will be installed inside the building in mid-February, just in time for a public unveiling of the Garden of Iron Rocks in the spring.
Taconite and iron
Edward Wilson Davis was known as the “father of taconite.” The University of Minnesota professor was regarded as one of the world’s foremost authorities on the processing of iron ore and taconite. In 1946, he received a patent for the development process that would convert taconite into iron ore. In 1955, his taconite pellet process allowed for the use of lower-grade iron ore and breathed new life into Minnesota’s iron range.
The Renaissance Revival-style Education Sciences Building originally housed the Mines Experiment Station. It was designed in 1923 by state architect Clarence Johnston, Sr., and in time became the Mineral Resources Research Center--the birthplace of the taconite refining process. The university began remodeling the 62,000-square-foot building, tucked in the far northwest corner of the Twin Cities campus in Minneapolis, in spring 2005. (The renovation was a finalist for "Redevelopment/Extensive Renovation" in The Business Journal's 2007 Best in Real Estate awards.) Elements of its past, such as industrial tools and machines and its skylight atrium, have been retained. Pipes and valves are exposed along the high ceilings, as are steel-support beams. The building currently houses three College of Education and Human Development units: the Department of Educational Psychology, the Center for Applied Research and Educational Improvement, and the Center for Early Education and Development.
For Stanislav, the artist, the Garden of Iron Mirrors came to her very quickly. “It was one of these ideas that come to you very, very late at night, or I think at this point, it was very early in the morning,” she said. The Chicago native found not only “excellent specimens” of taconite during her rock-finding expedition at Cliff's Erie mine near Virginia, but gained a greater appreciation of her host state.
“It was my first time in a mine, and it was really an amazing and very educational experience for me,” she said. Garden of Iron Mirrors is, in a way, her tribute to Minnesota’s landscape.
“I would like people to go away from this sculptural installation with regard and further understanding of the location and the building's history,” she added. “And I want them to also have a beautiful physical experience that adds to their day.”
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Growing Concerns
A parenting question-and-answer column with Dr. Martha Erickson of the University of Minnesota
Question: Our daughter is clamoring to be allowed to go shopping at the mall with friends (without an adult along) when she turns 12 in a few weeks. We’re hearing the familiar line, “All the other parents let their kids,” but we’re not sure she’s old enough for that kind of independence. What do you think?
Answer: At age 11, children are eager to get out from under their parents’ constant supervision and spread their wings. But whether or not they are ready for the freedom they desire depends on both the child and the context. Here are a few things to consider as you make a decision that is right for your daughter:
• How responsible and trustworthy has your daughter been in other situations? Does she follow through with things you ask her to do? If you leave her on her own at home for brief periods, can you count on her to behave well and make good choices?
• Does your daughter know what to do if she finds herself in a dangerous or uncomfortable situation? For example, what would she do if approached by a stranger at the mall? Or pressured by peers to do something that is against your family values? Don’t take these skills for granted. Children benefit from parents’ direct teaching, followed by opportunities to practice specific things to say or do in tough situations.
• Is the mall a relatively safe, well-monitored, crime-free environment? And how will your daughter and her friends get to and from the mall? Will a responsible adult be driving both ways? Is there a safe, well-lighted place to wait for the ride home?
• Are your daughter’s friends trustworthy, and do you know their parents? Whatever the age of your children, it is always wise to get to know their friends and their parents. It is natural that your daughter will push for greater independence over the next few years, and your job will be to encourage that independence within safe, healthy limits. That task will be much easier if you maintain close communication with the parents of the other children her age. When parents join together to set community rules and expectations about young people’s behavior, the old “all the other parents…” line goes out the window. And young people feel secure in the knowledge that parents care about their safety and well-being.
Once you decide your daughter is ready to go shopping independently, it’s important to communicate clear expectations. For example, for safety, you might specify that she should always be with at least one friend. Perhaps you’ll decide that shopping is OK as long as her schoolwork is completed first. And what about time? At any age, too much mall time is not good. Although young people need unstructured time with friends, they also need time in supervised activities that build skills, confidence and positive connections to school and community.
Dr. Erickson is a senior fellow and director of the Harris Programs in the Center for Early Childhood Education at the University of Minnesota
Want to hear more parenting advice?
Dr. Erickson and her daughter can be heard every Sunday, from 2 - 4 pm, on “Good Enough Moms,” on FM107.1 radio in the Twin Cities or via Webcast at www.FM1071.com
