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Lionel Sobehart

After a brief run-in with Jupiter’s gravitational field in the 1970s, the comet Wild 2 bid adieu to the Kuiper Belt and hurtled toward the inner solar system. As it neared the sun, Wild 2 formed a tail, catching the attention of NASA scientists eager to get their hands on samples of extraterrestrial comet dust.

Researchers at Washington University have worked with NASA to analyze space particles since the Apollo missions 30 years ago. NASA’s Stardust spacecraft, launched on a seven year mission in 1999, collected samples from Wild 2’s tail for over 50 research teams around the world. Two of those research teams are in University labs.

Stars don’t live forever. “In their lifetime, they shed dust particles into space. This dust flies around, and then they get eaten up by other stars or get incorporated into other bodies,” said Frank Stadermann, senior research scientist in physics.

Washington University’s physics department was the only group that found a grain of stardust in their allotted sample, thus “justifying the name of the entire NASA mission,” said Stadermann.

“Comets are particularly interesting because they are small bodies that come from the outer edge of the solar system,” said Stadermann, adding that this is NASA’s first sample of comet material.

The Stardust spacecraft went on a mission that would have made Spaceman Spiff green with envy. A collection device that looks like a tennis racket took a swipe at the comet’s tail. The grid part of the racket was filled with aerogel, the lightest manmade solid ever produced. “It looks like frozen smoke,” said Stadermann.

Stardust trapped the dust particles in the aerogel, as well as a few grains that collided with its aluminum frame going at speeds of 14,000 miles per hour. One of the dust particles found in a microscopic crater on the frame came from a star older than the sun.

“We knew comets come from the outer edge of the solar system where it’s very cold.it’s essentially a cosmic freezer. This cosmic freezer has preserved material for 4.5 billion years. That is the time when the solar system formed,” explained Stadermann. He said that while they do not know the exact age of the stardust particle, they know it is older than 4.5 billion years.

By examining the comet’s tail, researchers can speculate about the building blocks of the early universe.

Stadermann worked with Ernst Zinner, research professor of physics; Christine Floss, research associate professor of physics; and Kuljeet Kaur Marhas, postdoctoral research associate in physics, while analyzing their first of 10 comet particles.

Preliminary examination of the samples went on for most of 2006. In a paper titled “Isotopic Compositions of Cometary Matter Returned by Stardust,” published in Science this past December, Stadermann and almost 50 other researchers wrote about the stellar particle and it’s elemental composition.

Before looking at the samples, researchers thought that Wild 2’s tail would be made up of ice and stardust from the early universe.

But when the samples came back, it became apparent that their hypothesis was wrong. The samples contained material from local sources inside our solar system.

Researchers can determine the origin of the grains by analyzing their isotopic content. An isotope is an element with a different number of neutrons in its nucleus. Using a mass spectrometer called a NanoSIMS, which measures the atomic weight of particles, University researchers found that the stardust speck had an unusual ratio of oxygen isotopes.

“In case of oxygen, there are three isotopes: 16, 17 and 18. This one grain Frank [Stadermann] found and analyzed has a higher abundance of oxygen 17. The ratio of 17 is much higher than what you find in a material from our lunar samples,” said Ernst Zinner.

Although no students were involved with the Stardust lab work, Stadermann said that he would welcome student participation down the road. “Because we will continue this work, I do hope that students will be involved in the future and have parts of this for their thesis work,” he said.

This entry was posted on Wednesday, January 17th, 2007 at 12:00 pm and is filed under News. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.