Soon, the jeep-size rover Curiosity will trace its first six-wheeled tracks over the Martian surface. Over the next 23 months, Curiosity will scoop dust and drill into rocks for clues to the Red Planet's past. Although those samples won't make it back to Earth, some Martian rocks are already catalogued and preserved here as part of NASA's astromaterials collection.

Astromaterials are fragments and particles from planets, asteroids, stars and other extraterrestrial bodies. Scientists gather the materials during manned and unmanned space missions or after they naturally land on Earth as meteorites.

"About one in one thousand of the meteorites that fall on Earth was actually knocked off Mars by ancient impacts," says Carlton Allen, the collection curator based at the NASA Johnson Space Center in Houston. He coordinates the efforts of more than 30 people to document, preserve and distribute the samples for researchers around the world. These samples help scientists understand the formation and development of the solar system.

The collection includes lunar rocks gathered by the Apollo astronauts, particles of cosmic dust collected by special aircraft swooping through the stratosphere, and atoms carried by the solar wind.

Chemical and physical analyses can trace rocks that end up on Earth back to their extraterrestrial sources. Scientists crush small pieces of meteorites to a fine powder and analyze how the particles bend light when suspended in oil. Or, they microscopically view thin sections of the rocks and classify their structures. Then, they compare the results with what they already know about the moon, Mars, asteroids and comets.

View the Heaven on Earth slide show.

The extraterrestrial samples require special laboratories and handling practices to keep their otherworldly purity. For example, during the six Apollo moon-landing missions astronauts photographed lunar rock and soil samples, packaged the materials in uniquely marked, vacuum-tight containers, and returned them to Earth in sterile conditions free from contamination by terrestrial gases. "The Apollo collection comprises some of the most carefully documented geologic material in the world," wrote Allen and colleagues in an article about NASA's extraterrestrial bounty, published in February 2011.

Another NASA mission to return extraterrestrial samples to Earth was the Genesis probe, launched in 2001. The spacecraft circled at one of the Earth–sun Lagrangian points for almost two and a half years, where the combined gravitational pull of the two bodies provides a stable position. The spacecraft's circular arrays gathered solar-wind ions streaming from the sun with wafers made of silicon, germanium and gold-on-sapphire, along with films of diamond-like carbon on silicon and other materials. Despite a crash landing in the Utah desert, which breached the spacecraft's container of over 400 samples of charged particles, some of the collected astromaterials proved pure enough for research. Genesis' data from the captured solar wind helped researchers rethink their understanding of the sun's and early solar system's composition.

Other successful sample return missions include NASA's Stardust spacecraft, which collected dust samples from Comet Wild 2 and the Japan Aerospace Exploration Agency's Hayabusa probe, which gathered asteroid samples in 2010. In the future Allen and his colleagues may preside over samples collected during planned missions to other asteroids and Mars. In addition to providing a window to other worlds and the distant past, these exotic, otherworldly artifacts are simply beautiful.

9 Comments

1. 1. Bill_Crofut 06:19 PM 8/8/12

   Re: "About one in one thousand of the meteorites that fall on Earth was actually knocked off Mars by ancient impacts..."
   
   That claim has perplexed me since the days of the celebrated, "Allan Hills 84001 (commonly abbreviated ALH 84001),"
   http://en.wikipedia.org/wiki/Allan_Hills_84001.
   
   The alleged Martian location has been touted as, "...the Eos Chasma, a branch of the enormous Valles Marineris canyon system...The analysis, based on the rock's mineral characteristics, was presented by Vicky Hamilton of the University of Hawaii...the claim remains highly controversial..." http://www.newscientist.com/article/dn8004.
   
   It raises the following question for me: What is the experimental evidence that an object can impact the martian surface with sufficient force to eject a meteorite on a trajectory to Earth?
   

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2. 2. RSchmidt in reply to Bill_Crofut 08:50 PM 8/8/12

   The trajectory doesn't have to be Earth. As the rocks are scattered some may end up in Earth's path and are then vacuumed up by Earth's gravity. Mar's gravity is much weaker than Earth's so early impacts likely sent up many tonnes of material. Material from objects impacting with Earth have also been sent into space. We call it the moon.

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3. 3. Bill_Crofut 10:18 AM 8/9/12

   RSchmidt,
   
   That explanation does not answer the question raised concerning experimental evidence as opposed to assertion. It does, however, raise another question: What objects impacting with Earth have been subsequently ejected onto the moon?
   

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4. 4. Bill_Crofut 10:20 AM 8/10/12

   Cigarshaped,
   
   "How to Etch Your Own Crater" may be an interesting laboratory experiment. How does it provide an answer to my question?
   

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5. 5. Tomato Addict 09:08 AM 8/13/12

   @Bill_Crofut: I expect this derives from practical impact experiments with results scaled up to the planetary scale. Physics and fluid dynamics are good at this sort of thing.

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6. 6. Cigarshaped 03:31 PM 8/13/12

   Bill, Your original question "What ..object can impact the martian surface with sufficient force to eject a meteorite ..?
   
   My first answer is that no OBJECT is needed to make direct contact. I doubt if more than a few % of craters were formed by IMPACT. The majority, which we now know pockmark every lump of rock out in the solar system, can only be the result of cosmic electrical interaction between these bodies. Just count how many circular craters also have raised central peaks. How many experiments can show impacts producing such neat shapes?
   
   Watch my video and see the way plasma works. Twin rotating filaments of intense current etch away material in a spinning motion, like a forked corkscrew. Thus the centre is often left untouched. So if this 'mechanism' is applied to Valle Marineris you can see the symmetrial reversed 'S' shape resulting from a pair of massive discharge bolts of energy. w^3.holoscience.com/wp/wp-content/uploads/2012/03/Valmar_arc.jpg. Read the article at w^3.holoscience.com/wp/spiral-galaxies-grand-canyons/
   
   Would you prefer to find a very big hammer and chizel to cut through 1" steel plate (impact)? Or would you switch on your super plasma cutting tool? The power is in the high currents possible when you are dealing with plasma in its 'arc' mode.
   
   As you can see from the lab video, plasma naturally forms into intertwining filaments, known as Birkeland Currents. Since visible space is 99.99% plasma, the currents available in space are virtually unlimited. Making a gash the size of Valle Marineris is the job of a few minutes work. The excess material is lofted into space and all over the surface, as we can see from robot photos.
   
   What agency or object caused this? A likely suspect, by the mythical records of humans around at the time, is Venus. The inexplicably hot and anti-rotating bad girl of ancient times, is very often referred to as a flaming comet. She was charged up and ready to zap! Astronomers treated her with awe and nations worshipped Baal, etc. Egypt worshipped her cometary form: w^3.gks.uk.com/comet-venus-velikovsky/

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7. 7. Bill_Crofut 10:28 AM 8/14/12

   Tomato Addict,
   
   Thank you for that information. Have you a source for one or more of those experiments?
   

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8. 8. Bill_Crofut 10:29 AM 8/14/12

   Cigarshaped,
   
   Using the “holoscience” entry you provided is a dead end. Revising it, i.e.,
   
   http://www.holoscience.com/wp/wp-content/uploads/2012/03/Valmar_arc.jpg
   
   does not lead to a video, but an image.
   
   Revising the second entry, i.e.,
   
   http://www.holoscience.com/wp/spiral-galaxies-grand-canyons/
   
   does lead to the following web page:
   
   “Spiral Galaxies & Grand Canyons.”
   
   Please allow me some time to digest that information.
   

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9. 9. Bill_Crofut 12:36 PM 8/14/12

   Cigarshaped,
   
   Having had the opportunity to read the online paper, “Spiral Galaxies & Grand Canyons,” one of the more significant statements for me is:
   
   “No one was there to witness the evolution of the Earth, so geologists have constructed an elaborate story about the history of the Earth.”
   
   You’ll bet no argument from me on that issue. However, how is your “Plasma Model” any different? For example,
   
   “The missing mass (shades of the purely gravitational thinking of astronomers) was not transported or buried on Mars. It was lofted toward space by blast and electrical forces.”
   
   How do you know that? How has your model been tested?
   

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