Martian spherules
Encyclopedia
Hematite
Hematite, also spelled as haematite, is the mineral form of iron oxide , one of several iron oxides. Hematite crystallizes in the rhombohedral system, and it has the same crystal structure as ilmenite and corundum...
inclusions discovered by the Mars rover
Mars Exploration Rover
NASA's Mars Exploration Rover Mission is an ongoing robotic space mission involving two rovers, Spirit and Opportunity, exploring the planet Mars...
Opportunity
Opportunity rover
Opportunity, MER-B , is a robotic rover on the planet Mars, active since 2004. It is the remaining rover in NASA's ongoing Mars Exploration Rover Mission...
at Meridiani Planum
Meridiani Planum
Meridiani Planum is a plain located 2 degrees south of Mars' equator , in the westernmost portion of Terra Meridiani. It hosts a rare occurrence of gray crystalline hematite...
on the planet Mars
Mars
Mars is the fourth planet from the Sun in the Solar System. The planet is named after the Roman god of war, Mars. It is often described as the "Red Planet", as the iron oxide prevalent on its surface gives it a reddish appearance...
. They are found in situ embedded in a sulfate
Sulfate
In inorganic chemistry, a sulfate is a salt of sulfuric acid.-Chemical properties:...
salt evaporitic matrix, and also loose on the surface.
The shapes by themselves don't reveal the particles' origin with certainty. "A number of straightforward geological processes can yield round shapes," said Dr. Hap McSween, an Opportunity science team member from the University of Tennessee
University of Tennessee
The University of Tennessee is a public land-grant university headquartered at Knoxville, Tennessee, United States...
, Knoxville. They include accretion
Accretion (geology)
Accretion is a process by which material is added to a tectonic plate or a landmass. This material may be sediment, volcanic arcs, seamounts or other igneous features.-Description:...
under water, but apparent pore
Porosity
Porosity or void fraction is a measure of the void spaces in a material, and is a fraction of the volume of voids over the total volume, between 0–1, or as a percentage between 0–100%...
s in the particles make alternative possibilities of meteor
METEOR
METEOR is a metric for the evaluation of machine translation output. The metric is based on the harmonic mean of unigram precision and recall, with recall weighted higher than precision...
impacts or volcanic eruptions
Volcano
2. Bedrock3. Conduit 4. Base5. Sill6. Dike7. Layers of ash emitted by the volcano8. Flank| 9. Layers of lava emitted by the volcano10. Throat11. Parasitic cone12. Lava flow13. Vent14. Crater15...
more likely origins, he said.
Micrometre
A micrometer , is by definition 1×10-6 of a meter .In plain English, it means one-millionth of a meter . Its unit symbol in the International System of Units is μm...
to more than 250 micrometers, similar spherules were found in Moon
Moon
The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...
soil samples collected by Apollo 12
Apollo 12
Apollo 12 was the sixth manned flight in the American Apollo program and the second to land on the Moon . It was launched on November 14, 1969 from the Kennedy Space Center, Florida, four months after Apollo 11. Mission commander Charles "Pete" Conrad and Lunar Module Pilot Alan L...
at the Procellarum Basin, and Apollo 14
Apollo 14
Apollo 14 was the eighth manned mission in the American Apollo program, and the third to land on the Moon. It was the last of the "H missions", targeted landings with two-day stays on the Moon with two lunar EVAs, or moonwalks....
near Mare Imbrium
Mare Imbrium
Mare Imbrium, Latin for "Sea of Showers" or "Sea of Rains", is a vast lunar mare filling a basin on Earth's Moon and one of the larger craters in the Solar System. Mare Imbrium was created when lava flooded the giant crater formed when a very large object hit the Moon long ago...
(Sea of Rains), the dark crater that dominates the Moon's face, and their properties were consistent with expectations for creation by meteor impacts.
"We see these strange round objects we're calling "spherules" embedded in the outcrop, like blueberries in a muffin
Muffin
A muffin is an American English name for a type of quick bread that is baked in small portions. Many forms are somewhat like small cakes or cupcakes in shape, although they usually are not as sweet as cupcakes and generally lack frosting. Savory varieties, such as cornbread muffins, also exist...
. The outcrop erodes away as it gets sandblasted, and the spherules (which seem to resist erosion better than the rest of the outcrop does) fall out and roll down the hill. Weird." said Dr. Steve Squyres
Steve Squyres
Steven W. Squyres is the Goldwin Smith Professor of Astronomy at Cornell University in Ithaca, New York. His research area is in planetary sciences, with a focus on large solid bodies in the solar system such as the terrestrial planets and the moons of the Jovian planets. Squyres is principal...
.
The spheres may have formed when molten rock was sprayed into the air by a volcano or a meteor impact. Or, they may be concretion
Concretion
A concretion is a volume of sedimentary rock in which a mineral cement fills the porosity . Concretions are often ovoid or spherical in shape, although irregular shapes also occur. The word 'concretion' is derived from the Latin con meaning 'together' and crescere meaning 'to grow'...
s, or accumulated material, formed by minerals coming out of solution
Solution
In chemistry, a solution is a homogeneous mixture composed of only one phase. In such a mixture, a solute is dissolved in another substance, known as a solvent. The solvent does the dissolving.- Types of solutions :...
as water diffused
Diffusion
Molecular diffusion, often called simply diffusion, is the thermal motion of all particles at temperatures above absolute zero. The rate of this movement is a function of temperature, viscosity of the fluid and the size of the particles...
through rock, he said on a February 9 press conference.
Not only are there spherules on the surface but they are also found deeper in the Martian soil
Soil
Soil is a natural body consisting of layers of mineral constituents of variable thicknesses, which differ from the parent materials in their morphological, physical, chemical, and mineralogical characteristics...
. The difference between these and ones which were found at the surface was that they had a very shiny surface, that created strong glints and glares which made them appear shiny or polished. On March 2, Opportunity mission scientists reported that they concluded a survey of the distribution of spherules in the bedrock. They found that the spherules spread out evenly and randomly inside the rocks, and not in layers. This supports the notion that they grew in place, since if their origin was related to volcanic or meteoric episodes one would expect layers of spherules as a "record in time" for each event. This observation was added to the list of evidence for liquid water being present at this rock site, where it is thought the spherules formed.
External links
- Science Magazine special issue on MER Opportunity initial results
- Press releases from JPL relating to Mars spherules: Initial press release, composition results
- Morphological Investigations of Martian Spherules, Comparisons to Collected Terrestrial Counterparts. Full text PDF.
- Sedimentary Concretions vs. Impact Condensates: Origin of the Hematitic Spherules of Meridiani Planum, Mars. Full text PDF.
- Ironstone Concretions - Analogs to Martian Hematite Spherules. Full text PDF.
- Moqui Marbles relations to Martian Spherules.
- ScienceDaily.com on Moqui marbles and Martian spherules
- http://www.scienzainrete.it/contenuto/articolo/Ce-vita-su-Marte relations to cyanobacteria and terrestrial stromatolites.