Astronomical Society of Coonabarabran

AMAZING IMAGES FROM MARS STUN SCIENTISTS

Phoenix in a race against time to study the Red Planet

By Liz Cutts

The arrival of the Phoenix on the surface of the Red Planet has captured international attention.

Since the Phoenix Lander touched down on Mars at 4.53pm (Pacific Time) on 25th May in an arctic region called Vastitas Borealis, the images relayed back have set the scientific world buzzing.

"The thing that really blew me away were the amazing images captured by the Mars Reconnaissance Orbiter of the Phoenix with its parachute prominently displayed coming down onto the surface of the planet," enthused Professor Fred Watson, Coonabarabran Astronomer-in-Charge of the Anglo-Australian Observatory at Siding Spring speaking on ABC's 702 breakfast show.

"This is the first time anyone has seen anything like this."

The Phoenix mission is the first chosen for NASA's Scout programme, an initiative for smaller, lower-cost spacecraft. Named for the resilient mythological bird, Phoenix uses a lander that was intended for use by the Mars Surveyor prior to its cancellation.

Phoenix released its parachute at an altitude of about 12.6 kilometers (7.8 miles) and a velocity of 1.7 times the speed of sound.

From a distance of about 760 kilometers above the surface of the Red Planet, Mars Reconnaissance Orbiter pointed its telescopic camera obliquely toward Phoenix shortly after it opened its parachute while descending through the Martian atmosphere. The image reveals an apparent 10-meter-wide parachute fully inflated. The bright pixels below the parachute show a dangling Phoenix.

These remarkable first-time images and close-up views of the planet's intriguing surface were relayed back to Earth to excited scientists.

"The images are really exceeding expectations," added Fred. "The photographs show the polygonally tessellated surface, which means that the surface is almost like a pavement with structure in it that is quite regular.

"Apparently this is a feature of terrestrial surfaces that are lying over permafrost and of course that is the whole point of the Phoenix Lander mission; we can now actually see the grooves.

"The grooves are caused by the contraction and expansion of the ice; they are the weak point in the surface. This is where Phoenix's robotic arm will be able to scoop up some material because scientists think that these cracks are where there is an interchange of vapour between the atmosphere and the sub-surface. This is where the action could really be happening.

"It is interesting to note that the parachute did not actually bring the Phoenix Lander down to the surface. First of all the heat shield burnt up in the normal way, then the parachute opened, slowing it down to a speed at which the thrusters could be fired to lower it gently.

"The atmospheric pressure on Mars is only one percent of what we have got here on Earth. The firings have to be very precise, although redundancy, or back-up, contingencies are built into space missions at a high level."

Mars is a cold desert planet with no liquid water on its surface. NASA's Mars Mission to land in icy soils near the north polar permanent ice cap of the Red Planet has been hailed as an unequivocal success.

The mission has two bold objectives - to study the history of water in the Martian arctic, while monitoring the polar climate and search for evidence of a habitable zone, and assess the biological potential of the ice-soil boundary.

In the Martian arctic, water ice lurks just below ground level. Discoveries made by the Mars Odyssey Orbiter in 2002 show large amounts of subsurface water ice in the northern arctic plain.

The Lander is targeting this circumpolar region using a robotic arm to dig through the protective top soil layer to the water ice below and, ultimately, to bring both soil and water ice to the Lander platform for sophisticated scientific analysis.

Aboard the deck of the Phoenix spacecraft are a suite of science instruments representing some of the most advanced technology ever sent to Mars.

But the Lander is in a race against time - the onset of a Martian winter. After ninety days the Phoenix will begin to shut down, as there is no sunlight at the Mars North Pole during winter with which to charge batteries and the frost covering the region will bury the Lander in ice.

Phoenix will be the first mission to return data from a polar region providing an important contribution to the overall Mars science strategy "Follow the Water".

It will also be instrumental in achieving the four science goals of NASA's long-term Mars Exploration Program; determining whether there was ever life on Mars, characterize the Martian climate and its geology and ultimately prepare for human exploration.

"I think so far Phoenix has been an amazing success story and everyone is literally over the moon about it," concluded Fred.

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Figure 1: (Phoenix landing) One of the stunning images that has amazed scientists clearly shows the Phoenix Lander suspended from its parachute (inset bottom left of picture) as it makes its way to the surface of Mars. Taken by the Mars Reconnaissance Orbiter, this is the first time one spacecraft has photographed another in the act of landing on the Red Planet. (Image credit NASA)

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Figure 2: (Mars surface) The tessellated surface of Mars and the Phoenix Lander can be clearly seen in this close up image captured by the High Resolution Imaging Science Experiment camera on NASA's Mars Reconnaissance Orbiter. (Image credit: NASA/JPL-Calech/University of Arizona)

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Figure 3: (Mars map) This map, centered on the north pole of Mars, is based on gamma rays from the element hydrogen, mainly in the form of water ice, and indicates that this very ice-rich region is due to a permanent polar cap of water ice on the surface. Elsewhere in this region, the ice is buried under several to a few tens of centimeters of dry soil. (Image Credit: NASA/JPL/UA)

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Figure 4: (Phoenix Lander) Artists concept of the Phoenix Lander (Image credit NASA)
Scientists have discovered what may be ice that was exposed when soil was blown away