Universe Today

Image credit: Hubble

NASA’s Hubble Space Telescope snapped this beautiful picture of the Planet Mars when our two planets were only 56 million kilometres apart. The picture was actually assembled from a series of exposures taken between 2220-2312 GMT (6:20 – 7:12 pm EDT) – 11 hours before the moment of opposition. The picture shows many details on the planet’s surface, including impact craters, clouds, and dust storms. The next opportunity for a picture like this will be in 26 months, when our two planets are reasonably close again.

NASA’s Hubble Space Telescope snapped this portrait of Mars within minutes of the planet’s closest approach to Earth in nearly 60,000 years. This image was made from a series of exposures taken between 5:35 a.m. and 6:20 a.m. EDT Aug. 27 with Hubble’s Wide Field and Planetary Camera 2. In this picture, the red planet is 34,647,420 miles (55,757,930 km) from Earth.

This sharp, natural-color view of Mars reveals several prominent Martian features, including the largest volcano in the solar system, Olympus Mons; a system of canyons called Valles Marineris; an immense dark marking called Solis Lacus; and the southern polar ice cap.

Olympus Mons [the oval-shaped feature just above center] is the size of Arizona and three times higher than Mount Everest. The dormant volcano resides in a region called the Tharsis Bulge, which is about the size of the U.S. and home to several extinct volcanoes. The three Tharsis Montes volcanoes are lined up just below Olympus Mons. Faint clouds are hovering over Arsia Mons, the southernmost of these volcanoes.

The long, dark scar, below and to the right of the Tharsis Bulge, is Valles Marineris, a 2,480-mile (4,000-km) system of canyons. Just below Valles Marineris is Solis Lacus, also known as the “Eye of Mars.” The dark features to the left of Solis Lacus are the southern highlands, called Terra Sirenum, a region riddled with impact craters. The diameters of these craters range from 31 to 124 miles (50 to 200 km).

The image was taken during the middle of summer in the Southern Hemisphere. During this season the Sun shines continuously on the southern polar ice cap, causing the cap to shrink in size [bottom of image]. The orange streaks are indications of dust activity over the polar cap. The cap is made of carbon dioxide ice and water ice, but only carbon dioxide ice is seen in this image. The water ice is buried beneath the carbon dioxide ice. It will only be revealed when the cap recedes even more over the next two months. By contrast, the Northern Hemisphere is in the midst of winter. A wave of clouds covers the northern polar ice cap and the surrounding region [top of image].

This view of Mars reveals a striking contrast between the Northern and Southern hemispheres. The Northern Hemisphere is home to volcanoes that may have been active about 1 billion years ago. These volcanoes resurfaced the north’s landscape, perhaps filling in many impact craters. The Southern Hemisphere is pockmarked with ancient impact craters, which appear dark because many are filled with coarser sand-sized particles.

Mars and Earth make a “close encounter” about every 26 months. These periodic encounters are due to the differences in the two planets’ orbits. Earth goes around the Sun twice as fast as Mars, lapping the red planet about every two years. Both planets have elliptical orbits, so their close encounters are not always at the same distance. In its close encounter with Earth in 2001, for example, Mars was about 9 million miles farther away. Because Mars was much closer during this year’s rendezvous, the planet will appeared 23 percent larger in the sky. Mars will not be this close again until 2287.

This photograph is a color composite generated from observations taken with blue, green, and red filters. A total of 11 filters, spanning a wide wavelength range?-from blue to near infrared?-were used during the observations. The shorter wavelengths show clouds and other atmospheric changes. The longer wavelengths, including the near infrared, reveal Martian surface features.

Original Source: Hubble News Release

On Wednesday, August 27 at 0951 GMT (5:51 am EDT) Mars and Earth will be only 56 million kilometres apart; the closest they’ve been in almost 60,000 years. Mars looks best in a telescope, where features like its polar ice cap and dust storms are visible, the planet is easy to spot with the naked eye. Just look to the south in the late evening and you can’t miss it; it currently outshines any other object in the sky other than the Moon. Astronomy clubs and observatories around the world are hosting events to give the public a chance to see the Red Planet – it will remain bright and close for several months.

Image credit: NASA

Since it arrived at Mars in 1997, the Mars Global Surveyor has been searching the surface of the Red Planet for carbonate minerals. Large quantities of this substance would be evidence that the planet was once warm and wet, with large oceans and seas on the surface. Surveyor has found trace quantities of the mineral spread evenly in the dust of the planet, but no deposits, indicating that the planet was probably always icy and cold.

After a decades-long quest, scientists analyzing data from NASA’s Mars Global Surveyor spacecraft have at last found critical evidence the spacecraft’s infrared spectrometer instrument was built to search for: the presence of water-related carbonate minerals on the surface of Mars.

However, the discovery also potentially contradicts what scientists had hoped to prove: the past existence of large bodies of liquid water on Mars, such as oceans. How this discovery relates to the possibility of ephemeral lakes on Mars is not known at this time.

The thermal emission spectrometer on Global Surveyor found no detectable carbonate signature in surface materials at scales ranging from three to 10 kilometers (two to six miles) during its six-year Mars mapping mission. However, the sensitive instrument has detected the mineral’s ubiquitous presence in martian dust in quantities between two and five percent. Planetary geologists Timothy Glotch Dr. Joshua Bandfield, and Dr. Philip Christensen of Arizona State University, Tempe, analyze the data from dust-covered areas of Mars in a report to be published Aug. 22 in the journal Science.

“We have finally found carbonate, but we’ve only found trace amounts in dust, not in the form of outcroppings as originally suspected. This shows that the thermal emission spectrometer can see carbonates — if they are there ? and that carbonates can exist on the surface today,” said Christensen, principal investigator for the instrument.

“We believe that the trace amounts that we see probably did not come from marine deposits derived from ancient martian oceans, but from the atmosphere interacting directly with dust,” Christensen said. “Tiny amounts of water in Mars’ atmosphere can interact with the ubiquitous dust to form the small amounts of carbonate that we see. This seems to be the result of a thin atmosphere interacting with dust, not oceans interacting with the big, thick atmosphere that many people have thought once existed there.”

“What we don’t see is massive regional concentrations of carbonates, like limestone,” said Bandfield, who spent a year refining the techniques that allowed the group to separate carbonate’s distinctive infrared signature from the spectrometer’s extensive database of infrared spectra, despite the mineral’s low concentrations and the masking effects of the martian atmosphere.

“We’re not seeing the white cliffs of Dover or anything like that,” he said. “We’re not seeing high concentrations, we’re just seeing ubiquitously low levels. Wherever we see the dust, we see the signature that is due to the carbonate.”

Because there are known to be deposits of frozen water on Mars, the findings have important implications for Mars’ past climate history.

“This really points to a cold, frozen, icy Mars that has always been that way, as opposed to a warm, humid, ocean-bearing Mars sometime in the past,” said Christensen. “People have argued that early in Mars history, maybe the climate was warmer and oceans may have formed and produced extensive carbonate rock layers. If that was the case, the rocks formed in those purported oceans should be somewhere.”

Although ancient carbonate rock deposits might have been buried by later layers of dust, Christensen pointed out that the global survey found no strong carbonate signatures anywhere on the planet, despite clear evidence of geological processes that have exposed ancient rocks.

Bandfield said that carbonate deposits in dust could be partially responsible for Mars’ atmosphere growing even colder, to become as cold, thin and dry as it is today.

“If you store just a couple percent of carbonate in the upper crust, you can easily account for several times the Earth’s atmospheric pressure,” Bandfield said. “You can store a lot of carbon dioxide in a little bit of rock. If you form enough carbonates, pretty soon your atmosphere goes away. If that happens, you can no longer have liquid water on the surface because you get to the point where liquid water is not stable.”

“The significance of these dramatic results may have to wait for the discoveries to be made by the Mars Exploration Rovers in 2004 and the Mars Reconnaissance Orbiter in 2006 and beyond,” stated Dr. Jim Garvin, NASA’s lead scientist for Mars exploration. What’s important is that we have found carbon-bearing minerals at Mars, which may be linked to the history of liquid water and hence to our quest to understand whether Mars has ever been an abode for life.”

The Mars Global Surveyor mission is managed for NASA’s Office of Space Science, Washington, D.C. by the Jet Propulsion Laboratory, a division of the California Institute of Technology, Pasadena. Arizona State University built and operates the Thermal Emission Spectrometer on Mars Global Surveyor. Lockheed Martin Space Systems, Denver, developed and operates the spacecraft.

Original Source: NASA/JPL News Release