Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Stardust in the laboratory

21.02.2006


Space science discoveries are being made in earthly labs



Reaching for the stars isn’t so out of reach these days. With the development of increasingly sophisticated instruments, researchers not only are able to get more detailed information about circumstellar and interstellar dust from afar by using advanced telescopes, but they also are now able to study actual stardust right in their own labs.

Since the discovery two decades ago that primitive meteorites contain microscopic grains of preserved stardust, physicists, chemists, astrophysicists and astronomers have taken advantage of this interstellar material that falls to Earth.


With new and ever-improving instruments to analyze these grains in the laboratory, researchers around the world are gaining new insights into the formation of the elements and the evolution of stars.

And with the successful January 2006 completion of NASA’s seven-year 2.88 billion mile round-trip Stardust mission to collect cometary and interstellar dust particles, researchers worldwide will be busy analyzing these samples for years to come looking for answers to fundamental questions about comets and the origin of the solar system.

Ernst K. Zinner, Ph.D., research professor of physics and of earth and planetary sciences, both in Arts & Sciences, at Washington University in St. Louis, provided an overview of the study of "Stardust in the Laboratory" Monday, Feb. 20, 2006, at the annual meeting of the American Association for the Advancement of Science (AAAS), held in St. Louis. He also participated in the AAAS "Exploring a Dusty Cosmos" press briefing that morning.

Zinner, the recipient of both the National Academy of Sciences’ J. Lawrence Smith Medal and the Meteoritical Society’s Leonard Medal, is a pioneer in the analysis of stellar dust grains found in primitive meteorites.

In 1987, Zinner and colleagues at Washington University and a group of scientists at the University of Chicago found the first stardust in a meteorite. Those presolar grains were specks of diamond and silicon carbide.

Since then, Zinner and other members of WUSTL’s Laboratory for Space Sciences’ research group have played leading roles in analyzing these grains in the laboratory and interpreting the results. The Laboratory for Space Sciences is part of the departments of Physics and Earth and Planetary Sciences and the McDonnell Center for the Space Sciences, all in Arts & Sciences.

It is generally believed that these grains were formed billions of years ago in the atmospheres of dying stars. "As a star dies," Zinner explains, "its atmosphere begins to expand and cool. Then ions turn into atoms, atoms form molecules and, eventually, molecules condense into grains."

The dust then is ejected into outer space, where it collects with gas and dust from other stars to form cold, dark clouds.

More than 4.5 billion years ago, one such cloud collapsed to form our solar system, and the dust -- literally pieces of distant and long-dead stars -- was preserved in meteorites.

By studying the isotopic composition of these grains, researchers are gaining new information on nuclear and chemical processes in stars and on conditions during the formation of the solar system.

Advancements in instrumentation

Using a microanalytic instrument called an ion microprobe to measure the proportions of specific isotopes, Zinner and his colleagues in the late 1980s and ’90s identified three types of interstellar grains -- silicon carbide, graphite and aluminum oxide -- and two important stellar sources of the grains.

The researchers determined through signature isotopic compositions that the grains came from red giant stars of low to medium mass during late stages of their evolution and from supernovae, massive stars that exploded at the end of their evolution.

These grains, Zinner explains, condensed when the envelope of red giants cooled during expansion or when supernovae exploded, thus preserving the elemental and isotopic composition of their stellar sources.

Zinner adapted the microprobe to permit precise isotopic measurements in samples weighing as little as a millionth of a millionth of a gram.

Isotopes are versions of an element that have different numbers of neutrons and, consequently, different masses. In the same way that a zoologist studies a set of footprints to learn about the animal that made them, Zinner and his colleagues study the isotopes in a grain to learn about the parent star -- its mass, age, composition and other characteristics.

The latest ion microprobe on the scene is the NanoSIMS (SIMS is short for Secondary Ion Mass Spectrometer), which can resolve objects smaller than a micrometer -- one millionth of a meter -- or 1/100th smaller than the diameter of a human hair.

Zinner and Frank J. Stadermann, Ph.D., senior research scientist in the Department of Physics in Arts & Sciences, helped design and test the NanoSIMS, which is made by CAMECA in Paris. At a cost of $2 million, Washington University acquired the first NanoSIMS in the world in 2000. There are now some 16 worldwide.

Ion probes direct a beam of ions onto one spot on a sample. The beam dislodges some of the sample’s own atoms, some of which become ionized. This secondary beam of ions enters a mass spectrometer that is set to detect a particular isotope. Thus, ion probes can identify grains that have an unusually high or low proportion of that isotope.

Unlike most other ion probes, however, the NanoSIMS can detect five different isotopes simultaneously. The beam can also travel automatically from spot to spot so that many hundreds or thousands of grains can be analyzed in one experimental setup.

Using the NanoSIMS, Ann Nguyen, Ph.D., at the time a WUSTL graduate student under Zinner, persevered -- after a WUSTL team had already sifted through 100,000 grains looking for a particular type of stardust without success -- and found the first silicate stardust in a meteorite.

In the March 5, 2004, issue of Science, Nguyen and Zinner describe nine specks of silicate stardust -- presolar silicate grains -- from one of the most primitive meteorites known. Silicate is a compound of silicon, oxygen and other elements such as magnesium and iron. Nguyen is now a postdoctoral research associate in the Department of Terrestrial Magnetism at the Carnegie Institution in Washington, D.C.

"Finding presolar silicates in a meteorite tells us that the solar system formed from gas and dust, some of which never got very hot, rather than from a hot solar nebula," Zinner says. "Analyzing such grains provides information about their stellar sources, nuclear processes in stars and the physical and chemical compositions of stellar atmospheres.

"The NanoSIMS was essential for this discovery," Zinner says. "These presolar silicate grains are very small -- only a fraction of a micrometer. The instrument’s high spatial resolution and high sensitivity made these measurements possible."

This detailed information about stardust proves that space science can be done in the laboratory, Zinner says. "Analyzing these small specks can give us information, such as detailed isotopic ratios, that cannot be obtained by the traditional techniques of astronomy," he adds.

Other instrumentation being used for studying very small particles include various kinds of mass spectrometers for chemical and isotopic analysis and radioactive dating, electron microscopes for chemical and structural analysis, and chemical and physical apparatus geared to the processing of microscopic material.

Zinner and Stadermann’s current project will be analyzing the three slices of a cometary dust particle they recently received from the Stardust mission -- the first U.S. mission since Apollo 17 in 1972 to bring back extraterrestrial material.

Susan Killenberg McGinn | EurekAlert!
Further information:
http://www.wustl.edu

More articles from Physics and Astronomy:

nachricht SwRI-led team discovers lull in Mars' giant impact history
26.04.2017 | Southwest Research Institute

nachricht New survey hints at exotic origin for the Cold Spot
26.04.2017 | Royal Astronomical Society

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

7th International Conference on Crystalline Silicon Photovoltaics in Freiburg on April 3-5, 2017

03.04.2017 | Event News

 
Latest News

Scientist invents way to trigger artificial photosynthesis to clean air

26.04.2017 | Materials Sciences

Ammonium nitrogen input increases the synthesis of anticarcinogenic compounds in broccoli

26.04.2017 | Agricultural and Forestry Science

SwRI-led team discovers lull in Mars' giant impact history

26.04.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>