Since then, nearly 200 scientists from around the globe have studied the minuscule grains, looking for clues to the physical and chemical history of our solar system. Although years of work remain to fully decipher the secrets of comet Wild 2, researchers are sure that it contains some of the most primitive and exotic chemical structures ever studied in a laboratory.
Preliminary results appear in a special section of the December 15 issue of Science. Overall, research efforts have focused on answering “big-picture” questions regarding the nature of the comet samples that were returned, including determining mineral structures, chemical composition, and the chemistry of the organic, or carbon-containing, compounds they carry. Carnegie researchers made key contributions to the latter effort. Out of seven papers in total, four involved Carnegie scientists from the Geophysical Laboratory (GL) and the Department of Terrestrial Magnetism (DTM).
“Carnegie enjoys a unique concentration of instrumentation and expertise to be able to engage in cutting-edge questions such as those posed by the Stardust mission,” said GL’s Andrew Steele.
Scientists have believed that comets formed long ago in the cool outer reaches of the solar system and thus largely consist of material that formed at cold temperatures and escaped alteration in the blast furnace of the inner solar nebula—the cloud of hot gases that condensed to form the Sun and terrestrial planets some 4.5 billion years ago.
According to the record contained in the Stardust grains, it appears that this hypothesis is about 90% right. Evidence from the ratios of certain isotopes—variants of atoms that have the same chemical properties, yet differ in weight—suggest that as much as 10% of the comet’s material formed in the hot inner solar nebula and was transported to the cold outer reaches where the comet came together as the Sun formed. Chief among these tell-tale isotopes are those of oxygen, for which the ratios resemble those seen in meteorites known to have formed in the inner solar system.
Yet, isotopic measurements of hydrogen and nitrogen made at DTM and elsewhere tell a different picture. “The presence of excesses of heavier isotopes—deuterium and nitrogen 15, to be specific—is a strong indication that some of the comet dust was around before the Sun formed,” said DTM’s Larry Nittler. “It’s really quite striking.”
The structures of the comet’s organic molecules tell a similar tale. “This comet’s organic material is really quite unusual compared to other extraterrestrial sources we have studied, such as meteorites and interstellar dust particles,” said GL’s George Cody. “Yet there are some important similarities that tell that us we are not dealing with matter that is totally foreign to our solar system.”
The samples contain very few of the stable ringed, or aromatic, carbon structures that are common on Earth and in meteorites. Instead, they have many fragile carbon structures that would most likely not have survived the harsh conditions in the solar nebula. These molecules also contain considerably more oxygen and nitrogen than even the most primordial examples retrieved from meteorites and exist in forms that are new to meteorite studies.
“These forms of carbon don’t look like what we find in meteorites, which is something like compacted soot from your chimney. The carbon compounds from this comet are a much more complicated mix of compounds,” commented GL’s Marc Fries. “It will be an exciting challenge to explain how these compounds formed and wound up in the comet.”
“This leads us to our next big question,” Cody remarked. “How could such fragile material have survived capture at 6 km/sec collision velocity?”
“At this point, every question we answer raises several more questions,” Nittler said. “But that is precisely what makes exploration so exciting and makes sample return so important. We now have the samples to study for many years to come.”
George Cody | EurekAlert!
Climate cycles may explain how running water carved Mars' surface features
02.12.2016 | Penn State
What do Netflix, Google and planetary systems have in common?
02.12.2016 | University of Toronto
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.
The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...
Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water
In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...
The efficiency of power electronic systems is not solely dependent on electrical efficiency but also on weight, for example, in mobile systems. When the weight of relevant components and devices in airplanes, for instance, is reduced, fuel savings can be achieved and correspondingly greenhouse gas emissions decreased. New materials and components based on gallium nitride (GaN) can help to reduce weight and increase the efficiency. With these new materials, power electronic switches can be operated at higher switching frequency, resulting in higher power density and lower material costs.
Researchers at the Fraunhofer Institute for Solar Energy Systems ISE together with partners have investigated how these materials can be used to make power...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
02.12.2016 | Medical Engineering
02.12.2016 | Agricultural and Forestry Science
02.12.2016 | Physics and Astronomy