NASA's Stardust Comet Probe Catches Dust from Interstellar Space

This false colour image shows a diffraction pattern from the first interstellar dust candidate Orion, collected by NASA's Stardust spacecraft in 2004. 

Credit: Zack Gainsforth

Seven tiny grains of rock captured by NASA's comet-chasing Stardust probe in 2004 may be visitors from the vast reaches of interstellar space, researchers say.

These interstellar dust motes from Stardust are fluffier and more diverse than expected, findings that could one day shed light on the origins of the solar system, scientists added.

Interstellar dust motes are bits of rock that permeate the enormous spaces between the stars.

NASA's comet-chasing Stardust probe

Supernovas and ancient stars produce interstellar dust, which contains elements such as carbon, nitrogen and oxygen that are necessary for life.

"By analyzing interstellar dust, we can understand our own origins," said lead study author Andrew Westphal, a planetary scientist at the University of California at Berkeley.

"Just as people go to Africa to look for fossil hominids, say, 4.5 million years old, trying to understand the origins of humanity, we want to look at stuff that helped form the solar system 4.5 billion years ago."



NASA launched the Stardust spacecraft in 1999 on a mission to collect dust from the wake of Comet Wild-2 (pronounced "Vilt-2").

Stardust rendezvoused with the comet in 2004 and, in 2006, returned its sample container back to Earth via parachute.

This image shows a top-down view of a dust particle impact on NASA's Stardust spacecraft Al foil collector. 

Credit: Stardust ISPE/ NRL

But while Stardust captured samples of Comet Wild-2 on one side of the craft's collector tray, the other side was pointed away from the comet to catch bits of interstellar dust in a stream emanating from about the direction of the constellation Ophiuchus.

These 12 images are a good representation of the closest images of comet Wild 2. 

The temporal sequence starts at the upper left and continues left to right on the first three rows. 

The overexposed and out-of-sequence images at the bottom are long exposures taken for autonomous tracking and yield the best jet images. 

All images were scaled to a constant image scale.

Credit: NASA Stardust

The tray was exposed to space for 195 days to capture particles in tiles of silica aerogel, a porous material resembling frozen smoke, which possesses a sponge-like structure that is 99.8 percent air.

Now, nearly a decade after Stardust's samples reached Earth, a preliminary analysis of the material suggests that seven of the dust motes the probe caught may have origins outside the solar system.

If that is confirmed, these tiny flecks of rock will represent the first specks of interstellar dust a spacecraft has ever returned to Earth.

"These are the very first contemporary samples of solid material from outside the solar system that we've identified," Westphal told reporters.

"Instead of looking at interstellar dust with telescopes, now we get to look at samples we collected from space with microscopes."

The keystoning apparatus cuts a picokeystone out of NASA's Stardust spacecraft interstellar dust collector at the Johnson Space Center in Houston. 

Credit: ESA /Rosetta /NAVCAM

New type of dust in Martian atmosphere discovered

A group of French and Russian scientists, including three specialists from Moscow Institute of Physics and Technology, has discovered a new peculiarity of the Martian atmosphere.

The scientists had analyzed satellite-acquired data and concluded that the dust particles in the planet's atmosphere can be of two types.

The scientific article which presents the results of the research in detail has been published in Icarus.

The Russian contributors to the research, Anna Fedorova, Alexander Rodin and Oleg Korablev, are the specialists of MIPT and SRI (IKI) RAS.

These scientists and their French colleagues from the Paris Observatory and LATMOS research laboratory have carried out a simultaneous analysis of the ultraviolet and infrared atmospheric extinctions from SPICAM, the spectrometer on the board of the orbital station Mars Express.

The results were received during the solar occultations at the beginning of Northern summer on Mars.

Before the Sun is completely eclipsed by the planetary disk, its rays pierce through the atmosphere and then get "caught" by the spectrometer's detector.

Having gone through the atmosphere, the solar rays show a different spectrum with the changes hinting at the atmosphere's makeup, the amount of various aerosols and the size of their particles.

This method was applied to understand the way the particles are distributed in the atmosphere.

The researchers have found out that the dust particles in the Martian atmosphere are not homogeneous, but can be roughly grouped into two modes.

• The first – coarser - mode is represented by both H2O ice grains with the average radius of 1.2 μm, and slightly smaller dust particles (R = 0.7 μm).
• The second mode is a lot finer, it is an aerosol which consists of much smaller particles with a radius of 0.04–0.07 μm.

Interestingly, the density number of the both modes is not that high. Even in the most "dusty" layers of the planet's atmosphere at altitudes of 20–30 km there are about 3.000 particles of the finer mode per 1 cm³, and not more than 2 particles of the coarser mode per 1 cm³.

If compared with what is considered the norm on Earth, the air with such dust density is rather clean (rooms are usually a lot dustier); yet, aerosols are important because they, according to the scientists, play a key role in forming the planet's climate.

Because of fine dust particles in the higher layers of the atmosphere, ice "embryos" are formed faster, which, in turn, influences clouds' build-up. The clouds are responsible for both precipitation and temperature condition on the planet's surface.

Analyzing the way the dust is spread in the atmosphere of the planet with regard to the altitude and geographical coordinates is crucial for forming the full picture of what is happening on Mars.

Besides that, the dust modes which the scientists have discovered confirm that Martian dust storms ("dust devils") are able to lift large quantities of substance from the planet's surface.

The researchers point out that the fact of fine dust presence in the atmosphere can contradict the previously obtained data on the existence of the supersaturated steam at the same altitude.

More information: Icarus, www.sciencedirect.com/science/… ii/S0019103513005332

ESA Herschel Survey: Completion largest census of dust in local galaxies

Collage of galaxies in the Herschel Reference Survey at infrared /submillimetre wavelengths by Herschel (left) and at visible wavelengths from the Sloan Digital Sky Survey (SDSS, right).

The Herschel image is coloured with blue representing cold dust and red representing warm dust; the SDSS image shows young stars in blue and old stars in red. 

Together, the observations plot young, dust-rich spiral/irregular galaxies in the top left, with giant dust-poor elliptical galaxies in the bottom right.

ESA /Herschel /HRS-SAG2 and HeViCS Key Programmes /Sloan Digital Sky Survey / L. Cortese (Swinburne University)

The largest census of dust in local galaxies has been completed using data from ESA’s Herschel space observatory, providing a huge legacy to the scientific community.

Cosmic dust grains are a minor but fundamental ingredient in the recipe of gas and dust for creating stars and planets but despite its importance, there is an incomplete picture of the dust properties in galaxies beyond our own Milky Way.

Key questions include how the dust varies with the type of galaxy, and how it might affect our understanding of how galaxies evolve.

Before concluding its observations in April 2013, Herschel provided the largest survey of cosmic dust, spanning a wide range of nearby galaxies located 50–80 million light-years from Earth.

The catalogue contains 323 galaxies with varying star formation activity and different chemical compositions, observed by Herschel’s instruments across far-infrared and submillimetre wavelengths.

A sample of these galaxies is displayed in a collage, arranged from dust-rich in the top left to dust-poor in the bottom right.

The dust-rich galaxies are typically spiral or irregular, whereas the dust-poor ones are usually elliptical.

Blue and red colours represent cooler and warmer regions of dust, respectively.

Dust is gently heated across a range of temperatures by the combined light of all of the stars in each galaxy, with the warmest dust being concentrated in regions where stars are being born.

For comparison, the galaxies are also shown in visible light images obtained by the Sloan Digital Sky Survey SDSS.

Here, blue corresponds to young stars – hot, massive stars that burn through their fuel very quickly and are therefore short-lived.

Conversely, red stars are older population – they are less massive and cooler, and therefore live for longer.

The Herschel observations allow astronomers to determine how much light is emitted by the dust as a function of wavelength, providing a means to study the physical properties of the dust.

The Grand Tack model: 'Rogue' asteroids may be normal

Credit: NASA/JPL-Caltech

To get an idea of how the early solar system may have formed, scientists often look to asteroids.

These relics of rock and dust represent what today's planets may have been before they differentiated into bodies of core, mantle, and crust.

In the 1980s, scientists' view of the solar system's asteroids was essentially static: Asteroids that formed near the sun remained near the sun; those that formed farther out stayed on the outskirts.

But in the last decade, astronomers have detected asteroids with compositions unexpected for their locations in space: Those that looked like they formed in warmer environments were found further out in the solar system, and vice versa. Scientists considered these objects to be anomalous "rogue" asteroids.

But now, a new map developed by researchers from MIT and the Paris Observatory charts the size, composition, and location of more than 100,000 asteroids throughout the solar system, and shows that rogue asteroids are actually more common than previously thought.

Particularly in the solar system's main asteroid belt—between Mars and Jupiter—the researchers found a compositionally diverse mix of asteroids.

The new asteroid map suggests that the early solar system may have undergone dramatic changes before the planets assumed their current alignment.

For instance, Jupiter may have drifted closer to the sun, dragging with it a host of asteroids that originally formed in the colder edges of the solar system, before moving back out to its current position.

Jupiter's migration may have simultaneously knocked around more close-in asteroids, scattering them outward.

Francesca DeMeo

"It's like Jupiter bowled a strike through the asteroid belt," says Francesca DeMeo, who did much of the mapping as a postdoc in MIT's Department of Earth, Atmospheric and Planetary Sciences.

"Everything that was there moves, so you have this melting pot of material coming from all over the solar system."

DeMeo says the new map will help theorists flesh out such theories of how the solar system evolved early in its history.

She and Benoit Carry of the Paris Observatory have published details of the map in Nature.

The compositional diversity seen in this new asteroid map may add weight to a theory of planetary migration called the Grand Tack model.

This model lays out a scenario in which Jupiter, within the first few million years of the solar system's creation, migrated as close to the sun as Mars is today.

During its migration, Jupiter may have moved right through the asteroid belt, scattering its contents and repopulating it with asteroids from both the inner and outer solar system before moving back out to its current position—a picture that is very different from the traditional, static view of a solar system that formed and stayed essentially in place for the past 4.5 billion years.

"That [theory] has been completely turned on its head," DeMeo says. "Today we think the absolute opposite: Everything's been moved around a lot and the solar system has been very dynamic."

DeMeo adds that the early pinballing of asteroids around the solar system may have had big impacts on Earth.

For instance, colder asteroids that formed further out likely contained ice. When they were brought closer in by planetary migrations, they may have collided with Earth, leaving remnants of ice that eventually melted into water.

"The story of what the asteroid belt is telling us also relates to how Earth developed water, and how it stayed in this Goldilocks region of habitability today," DeMeo says.

More information: Paper: dx.doi.org/10.1038/nature12908

Mars' Tale of Fire and Water written in Dust - Video

For over a decade, Europe's Mars Express has detected a wide range of minerals on the surface. 

Levels of olivine and pyroxene speak of volcanoes and ferric oxide whispers of water in the red dust. This global map refines future landing sites. 

Credit: ESA

NASA Mars HiRISE Image: Starburst Spider Terrain

Credit: NASA Mars HiRISE

Mars’ seasonal cap of carbon dioxide ice (dry ice) has eroded many beautiful terrains as it sublimates (goes directly from ice to vapor) every spring.

In this region we see troughs that form a starburst pattern.

In other areas these radial troughs have been referred to as “spiders,” simply because of their shape.

In this region the pattern looks more dendritic as channels branch out numerous times as they get further from the center.

The troughs are believed to be formed by gas flowing beneath the seasonal ice to openings where the gas escapes, carrying along dust from the surface below.

The dust falls to the surface of the ice in fan-shaped deposits.

You can find more images here