NASA Finds Another Solar System Mystery based on Stardust mission

SPACE CENTER, Houston – NASA scientists have a new mystery to solve: How did materials formed by fire end up on the outermost reaches of the solar system, where temperatures are the coldest?

The materials were contained in dust samples captured when the robotic Stardust spacecraft flew past the comet Wild 2 in 2004. A 100-pound capsule tied to a parachute returned the samples to Earth in January.

The samples include minerals such as anorthite, which is made up of calcium, sodium, aluminum and silicate; and diopside, made of calcium magnesium and silicate. Such minerals only form in very high temperatures.

“That's a big surprise. People thought comets would just be cold stuff that formed out ... where things are very cold,” said NASA curator Michael Zolensky. “It was kind of a shock to not just find one but several of these, which implies they are pretty common in the comet.”

The discovery raises questions about where the materials in comets form, he added.

One theory is that particles from the outer reaches of the solar system slowly move toward the sun, where they are set ablaze and shot back out. A scientific model once suggested that might be a natural occurrence, but it wasn't accepted because materials tend to cluster in zones the farther they are from the sun, Zolensky said.

“It raises a question of why we still see zoning in the asteroid belt. It is a big mystery now,” Zolensky said. “It's kind of really exciting.”

He said it is also possible that the comet particles could have been formed in another solar system and catapulted into our solar system.

To determine where the particles originated, scientists are now studying their isotopic makeup. About 150 scientists worldwide have been studying the dust since it arrived.

During the $212 million mission, the Stardust spacecraft looped around the sun three times to capture the interstellar and comet dust. The comet dust was captured in a silicone-based material contained in a tennis racket-sized collector mitt.

The mother ship, which has traveled nearly 3 billion miles, remains in permanent orbit around the sun. The next time it flies by Earth will be in January 2009.

Don Brownlee, a University of Washington astronomer who is the mission's principal scientist, said in a few weeks or months he and his colleagues hope to know more.

“It depends on whether the isotopic composition indicates these grains are from our solar system or from another star,” he said. “It's a real exciting mystery story. So stay tuned.”

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http://stardust.jpl.nasa.gov/news/status/060313.html

Erica Hupp/ Merrilee Fellows
Headquarters, Washington
(202) 358-1237/ (818) 393-0754

William Jeffs
Johnson Space Center, Houston
(281) 483-5111

March 13, 2006

RELEASE: 06-091

NASA's Stardust Findings May Alter View of Comet Formation
Samples from comet Wild 2 have surprised scientists, indicating the formation of at least some comets may have included materials ejected by the early sun to the far reaches of the solar system.

Scientists have found minerals formed near the sun or other stars in the samples returned to Earth by NASA's Stardust spacecraft in January. The findings suggest materials from the center of the solar system could have traveled to the outer reaches where comets formed. This may alter the way scientists view the formation and composition of comets.

"The interesting thing is we are finding these high-temperature minerals in materials from the coldest place in the solar system," said Donald Brownlee, Stardust principal investigator from the University of Washington, Seattle.

Scientists have long thought of comets as cold, billowing clouds of ice, dust and gases formed on the edges of the solar system. But comets may not be so simple or similar. They may prove to be diverse bodies with complex histories. Comet Wild 2 seems to have had a more complex history than thought.

"We have found very high-temperature minerals, which supports a particular model where strong bipolar jets coming out of the early sun propelled material formed near to the sun outward to the outer reaches of the solar system," said Michael Zolensky, Stardust curator and co-investigator at NASA's Johnson Space Center, Houston. "It seems that comets are not composed entirely of volatile rich materials but rather are a mixture of materials formed at all temperature ranges, at places very near the early sun and at places very remote from it."

One mineral found in the material brought back by Stardust is olivine, a primary component of the green sand found on some Hawaiian beaches. It is among the most common minerals in the universe, but scientists were surprised to find it in cometary dust.

Olivine is a compound of iron, magnesium and other elements. The Stardust sample is primarily magnesium. Along with olivine, the dust from Wild 2 contains high-temperature minerals rich in calcium, aluminum and titanium.

Stardust passed within 149 miles of comet Wild 2 in January 2004, trapping particles from the comet in an exposed gel. Its return capsule parachuted to the Utah desert on Jan. 15. The science canister with the Wild 2 sample arrived at Johnson on Jan. 17. Samples have been distributed to approximately 150 scientists for study.

"The collection of cometary particles is greater than we ever expected," said Stardust Deputy Principal Investigator Peter Tsou of NASA's Jet Propulsion Laboratory, Pasadena, Calif. "The collection includes about two dozen large tracks visible to the unaided eye."

The grains are tiny, most smaller than a hair's width. Thousands of them appear to be embedded in the glass-like aerogel. A single grain of 10 microns, only one-hundredth of a millimeter (.0004 inches), can be sliced into hundreds of samples for scientists.

In addition to cometary particles, Stardust gathered interstellar dust samples during its seven-year journey. The team at Johnson's curatorial facility hopes to begin detailed scanning of the interstellar tray within a month. They will initiate the Stardust at Home project. It will enable volunteers from the public to help scientists locate particles.

After registering, Stardust at Home participants may download a virtual microscope. The microscope will connect to a server and download "focus movies." The movies are images of the Stardust Interstellar Dust Collector from an automated microscope at the Cosmic Dust Lab at Johnson. Participants will search each field for interstellar dust impacts.

NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages the Stardust mission for NASA's Science Mission Directorate, Washington. Lockheed Martin Space Systems, Denver, developed and operated the spacecraft.

Stardust science team members presented their first findings this week at the annual Lunar and Planetary Science Conference in League City, Texas.

For more information about Stardust on the Web, visit:

http://www.nasa.gov/stardust

For information about NASA and agency programs on the Web, visit:

http://www.nasa.gov/home

didn't check the links, probably some are goners:

Did Jupiter Bully Other Planets in Sibling Rivalry?
by Robert Roy Britt
8 December 1999
One possible explanation, discussed in Thursday's issue of the journal Nature, is that Uranus and Neptune formed much closer to the center of the action than their current positions might indicate. In this scheme, Jupiter and Saturn were bullies of a protoplanetary playground, shoving the other two future giants out of the way.
Jupiter gave birth to Uranus and Neptune
by Dr David Whitehouse
8 December 1999
Not too long ago, scientists regarded the orbits that the planets circle our Sun as being the ones they were born in. Now they are realising that this is not the case. Uranus and Neptune may have migrated outwards and Jupiter may have come in from the outer cold. Scientists have always been slightly puzzled by the positions of Uranus and Neptune because in their present locations it would have taken longer than the age of the Solar System for them to form. Scientists from Queen's University suggest that the four giant planets started out as rocky cores in the Jupiter-Saturn region, and that the cores of Uranus and Neptune were tossed out by Jupiter's and Saturn's gravity.
Jupiter's Composition Throws Planet-formation Theories into Disarray
by Robert Roy Britt
Nov 17 1999
Examining four-year-old data, researchers have found significantly elevated levels of argon, krypton and xenon in Jupiter's atmosphere that may force a rethinking of theories about how the planet, and possibly the entire solar system, formed. Prevailing theories of planetary formation hold that the sun gathered itself together in the center of a pancake-shaped disk of gas and dust, then the planets begin to take shape by cleaning up the leftovers. In Jupiter's current orbit, 5 astronomical units from the sun, temperatures are too warm for the planetesimals to have trapped the noble gases. Only in the Kuiper belt -- a frigid region of the solar system more than 40 AU from the sun -- could planetesimals have trapped argon, krypton and xenon.

While lead researcher Tobias Owen does not put much stock in the idea that Jupiter might have migrated inward to its present position, other scientists on the team say the idea merits consideration. Owen expects the probes will find similarly high levels of noble gases in Saturn, Uranus and Neptune. Hints of these gases have even been found in the thick atmosphere of Venus, another planet now begging more study.
Newfound Moons Tell Secrets of Solar System
by Henry Fountain
August 12, 2003
The fact that most of the satellites' orbits are retrograde and eccentric speaks volumes about their origins: They had to have come from elsewhere, and been captured by the planets at some point. If they formed at the same time as the planets, from the spinning nebular disk, their orbits would be nearly circular and in the same direction as the planets' rotation, like the "regular" moons... In the case of the irregular satellites, they could not have shifted from an orbit around the Sun to an orbit around one of the giant planets without slowing down -- through friction in an atmosphere, perhaps; the influence of gravity; or a collision with another object... But there are two other possibilities for capture, Dr. Nesvorny said. One is that rapid growth of the core led to a corresponding increase in gravity, enough to pull down a nearby object. The other is that captured objects were a result of a collision between two planetesimals, the force of the collision being enough to dissipate the energy of at least one of them. Either of these two theories may be a more likely explanation for the satellites of Uranus and Neptune, which formed differently from Jupiter and Saturn, without the large amounts of gas.

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