NASA MRO Image: Strong evidence of Granite on Mars

NASA's Mars Reconnaissance Orbiter (MRO) is providing new spectral "windows" into the diversity of Martian surface materials. 

Here in a volcanic caldera, bright magenta outcrops have a distinctive feldspar-rich composition. 

Credit: NASA/JPL/JHUAPL/MSSS

Researchers now have stronger evidence of granite on Mars and a new theory for how the granite – an igneous rock common on Earth—could have formed there, according to a new study.

The findings suggest a much more geologically complex Mars than previously believed.

Large amounts of a mineral found in granite, known as feldspar, were found in an ancient Martian volcano.

Further, minerals that are common in basalts that are rich in iron and magnesium, ubiquitous on Mars, are nearly completely absent at this location.

The location of the feldspar also provides an explanation for how granite could have formed on Mars.

Granite, or its eruptive equivalent, rhyolite, is often found on Earth in tectonically active regions such as subduction zones.

This is unlikely on Mars, but the research team concluded that prolonged magmatic activity on Mars can also produce these compositions on large scales.

"We're providing the most compelling evidence to date that Mars has granitic rocks," said James Wray, an assistant professor in the School of Earth and Atmospheric Sciences at the Georgia Institute of Technology and the study's lead author.

The research was published November 17 in the Advance Online Publication of the journal Nature Geoscience. The work was supported by the NASA Mars Data Analysis Program.

More information: J Wray, et al. "Prolonged magmatic activity on Mars inferred from the detection of felsic rocks." Nature Geoscience, 2013. http://dx.doi.org/DOI: 10.1038/NGEO1994.

Venus Express Maps: Finds Oceans and Granite

The first temperature map (centered at the south pole) of the planet's southern hemisphere at infrared wavelengths, charted with Venus Express's Visible and Infrared Thermal Imaging Spectrometer, VIRTIS. Higher temperatures (red) correspond to lower altitudes, while lower temperatures (blue) correspond to higher altitudes. Credit: ESA/VIRTIS/INAF-IASF/Obs. de Paris-LESIA

Venus is a Home from Home

Venus may once have been more Earth-like, with volcanic activity and an ocean of water, a new map of the toasty planet's southern hemisphere suggests.

The map comprises over a thousand individual images, recorded between May 2006 and December 2007 by the European Space Agency's Venus Express spacecraft. It gives astronomers another tool in their quest to understand why Venus is so similar in size to Earth and yet has evolved so differently.

Thick Clouds obscure Venus

Normal visible light cameras cannot see the surface of Venus because it is covered in clouds. So, Venus Express uses a particular frequency of infrared wavelength to 'see' through them.

Although radar systems have been used in the past to provide high-resolution maps of Venus's surface, Venus Express is the first orbiting spacecraft to produce a map that hints at the chemical composition of the rocks.

Rocky clues

The new data is consistent with suspicions that the highland plateaus of Venus are ancient continents, once surrounded by ocean that might have evaporated away into space and produced by past volcanic activity.

"This is not proof, but it is consistent. All we can really say at the moment is that the plateau rocks look different from elsewhere," said Nils Müller of the the University Münster and DLR Berlin, who headed the mapping efforts.

Water

Water is a key to life as we know it. And though there are no signs of past or present biology on the suffocating surface Venus, some astronomers have speculated that the its clouds could harbor life.

The rocks look different because of the amount of infrared light they radiate into space. Different surfaces radiate different amounts of heat at infrared wavelengths due to a material characteristic known as emissivity, which varies in different materials.