Astronomy Now Online
Home Magazine Resources Store


Top Stories


Evidence for liquid water on Mars today

...Droplets of salty liquid water mixed with mud have been detected on a leg of the Mars Phoenix Lander...

read more

New evidence for dark matter around
small galaxies

...Astronomers studying the Perseus galaxy cluster with the Hubble Space Telescope have uncovered a new line of evidence that suggests galaxies are embedded in halos of dark matter...

read more

Planck and Kepler Exclusive Interviews

...Astronomy Now talks to the scientists and engineers behind the Herschel and Planck missions...

read more



Spaceflight Now +



Subscribe to Spaceflight Now Plus for access to our extensive video collections!
How do I sign up?
Video archive

STS-120 day 2 highlights

Flight Day 2 of Discovery's mission focused on heat shield inspections. This movie shows the day's highlights.

 Play

STS-120 day 1 highlights

The highlights from shuttle Discovery's launch day are packaged into this movie.

 Play

STS-118: Highlights

The STS-118 crew, including Barbara Morgan, narrates its mission highlights film and answers questions in this post-flight presentation.

 Full presentation
 Mission film

STS-120: Rollout to pad

Space shuttle Discovery rolls out of the Vehicle Assembly Building and travels to launch pad 39A for its STS-120 mission.

 Play

Dawn leaves Earth

NASA's Dawn space probe launches aboard a Delta 2-Heavy rocket from Cape Canaveral to explore two worlds in the asteroid belt.

 Full coverage

Dawn: Launch preview

These briefings preview the launch and science objectives of NASA's Dawn asteroid orbiter.

 Launch | Science

Become a subscriber
More video



Another piece in the puzzle of Mars climate

BY DR EMILY BALDWIN

ASTRONOMY NOW

Posted: 20 March, 2009

According to new analysis of an eroded crater, a large scale depositional process has been at work in the equatorial regions of Mars that has implications for the climatic history of the planet.

The evidence comes from a Mars Express study of the mineralogical composition of the Aram Chaos region, a crater 280 kilometres in diameter lying almost directly on the Martian equator. The OMEGA instrument data shows a significant amount of sulphates and ferric oxides, the latter of which is more commonly known as rust, and which gives Mars its red tone.

The Aram Chaos region of Mars, a crater 280 km in diameter, where OMEGA detected large-scale deposits of ferric oxides. The inset shows the region in relation to other areas where the same minerals have been detected. Image: NASA/MGS/MOLA/THEMIS.

Although ferric oxide is common across the red planet, in the dark deposits of Aram Chaos there is a four-fold increase in the spectral signature of ferric oxides, which means that some process has concentrated the oxides in this location. Ferric oxides are generally found with sulphates but, in this case, the lighter sulphates have been blown away, leaving the ferric oxides exposed.

“They have accumulated in dark deposits at the bottom of sulphate cliffs,” says Stephane Le Mouelic, Universite de Nantes. The scientists say that this implies that the ferric oxides have been uncovered by erosion before dropping to the base of the cliffs. The dunes in this region are also enriched in ferric oxides.

While an interesting discovery for this region of Mars, the phenomenon is not exclusive to Aram Chaos. NASA’s Opportunity rover discovered ferric oxide deposits - nicknamed blueberries - one thousand kilometres away in Meridiani Planum. In addition, Valles Marineris, 3000 kilometres away, also shows similar deposits. The new detection of a similar chemistry in Aram Chaos therefore links together widely separated areas of Mars, and the scientists suspect there could be even more examples in other locations.

Mars Express has been orbiting the red planet for over five years. Image: ESA/Medialab.

“OMEGA is sensitive to the first hundreds of microns of the surface. So, a layer of Martian dust just one millimetre thick will hide the signature from us,” says Marion Masse, lead author on the paper describing these results. Thanks to wind erosion, which has occurred at Aram Chaos, the dust cover has been swept away to reveal the composition of the underlying rocks.

For the time being, however, the true extent and nature of the accumulation process remains a mystery. The science team are now exploring different mechanisms that could have caused it, from atmospheric precipitation such as rain or snow, to volcanic ashes or glacial deposits. Whatever the conclusion, the results will contribute to scientist's understanding of the past climatic and surface process that have shaped the planet.

The findings are discussed in the Journal of Geophysical Research.

The Planets
From tiny Mercury to distant Neptune and Pluto, The Planets profiles each of the Solar System's members in depth, featuring the latest imagery from space missions. The tallest mountains, the deepest canyons, the strongest winds, raging atmospheric storms, terrain studded with craters and vast worlds of ice are just some of the sights you'll see on this 100-page tour of the planets.
 GET YOUR COPY

Hubble Reborn
Hubble Reborn takes the reader on a journey through the Universe with spectacular full-colour pictures of galaxies, nebulae, planets and stars as seen through Hubble's eyes, along the way telling the dramatic story of the space telescope, including interviews with key scientists and astronauts.
 GET YOUR COPY

3D Universe
Witness the most awesome sights of the Universe as they were meant to be seen in this 100-page extravaganza of planets, galaxies and star-scapes, all in 3D!
 GET YOUR COPY


HOME | NEWS ARCHIVE | MAGAZINE | SOLAR SYSTEM | SKY CHART | RESOURCES | STORE | SPACEFLIGHT NOW

© 2014 Pole Star Publications Ltd.