Star Talk: Phoenix mission to search for water in Mars polar region

Phoenix, the most recent NASA mission to Mars, rose from the ambitions of the Mars Polar Lander proj

A resurrected $420 million space “bird” took to the air last summer, and on May 25 it will set down on a planet whose distance is more than 170 million miles from Earth.

Phoenix, the most recent NASA mission to Mars, rose from the ambitions of the Mars Polar Lander project, an unsuccessful attempt in 1999 to place a robotic lander on the Martian polar surface. Lost upon descent when its engines shut down before landing, the Polar Lander was reincarnated in 2003 as the Phoenix mission and was launched last August.

Phoenix will land in the distant northern plains of Mars, a site that is farther north than where any spacecraft has ever landed on the Red Planet and the Earth equivalent of a location in northern Alaska. Phoenix will touch down there because spacecraft orbiting Mars have gathered evidence for water-ice within the first few feet of the surface at this high northern latitude.

Consequently, the nearly half-ton Phoenix is equipped with a robotic arm designed to dig trenches, scoop up soil samples, and place these samples into miniature laboratories onboard the lander. These laboratories consist of high-temperature ovens along with instruments that will analyze the Martian ice and soil samples.

Once the samples are loaded into the on-board ovens, the specimens will be heated to as much as 800 degrees Fahrenheit and the gases that are released by the ice and soil samples will be assessed for their chemical nature.

Cameras at work

To provide full-color, close-up images of these samples, there is a camera mounted just above the scoop of the robotic arm. This camera will also provide views of prospective samples, the immediate ground around the lander, and the bottom and sidewalls of the trenches that are dug by the robotic arm. Close examination of the trench allows for determining the fine-scale texturing and layering of the Martian soil.

However, the camera on the robotic arm is not the only camera on the lander. The “eyes” for the mission is a stereo imager that allows mission controllers to view high-resolution, stereo and panoramic images of the Martian arctic.

As this camera surveys the region surrounding the landing site, the images that it takes will be used to map the nearby geology and assist in determining where the lander’s robotic arm should dig. The imager will also monitor the polar atmosphere of Mars and make measurements of the dust and clouds in the planet’s arctic air.

When Phoenix reaches Mars, it will have traveled 423 million miles on its journey to catch the Red Planet in its orbit around the sun. At that time, the spacecraft will be moving at over 12,000 miles per hour, the speed at which it will strike the top of the thin Martian atmosphere. In only a matter of seven minutes, Phoenix will slow to five miles per hour by using its heat shield, then parachute and finally its descent rockets to make a soft touchdown.

Why Mars?

“Follow the water” is NASA’s mantra and Mars is the place to look. Although liquid water does not currently exist on the surface of Mars, evidence gathered from the Mars Global Surveyor and Mars Odyssey orbiter missions, as well as the Mars Exploration Rovers (Spirit and Opportunity), suggests that liquid water did exist on Mars long ago. Images taken from orbit show channels where water may have once flowed in Martian canyons and then collected in shallow lakes billions of years ago.

Other evidence suggests that there could have been some liquid water in Mars’ polar region as recently as 100,000 years ago. This might be possible because of the changing tilt of the planet toward the sun on that time scale. These polar regions could have received more sunlight in the past than shines on these sections of the planet today.

What’s next?

The next NASA mission to Mars will consist of a rover that is twice as long and three times as massive as the current rovers. Called the Mars Science Laboratory, its design includes instruments that can identify organic compounds such as proteins and amino acids, compounds that are essential to life.

Launch date for the Mars Science Laboratory is currently planned for the fall of 2009 with an arrival date at Mars of October 2010.

May sky

Mars is now visible very high above the western horizon as the sky gets completely dark. This planet is still positioned against the stars of Gemini, as it was last month, but on May 5, it crosses this constellation’s border moving rapidly eastward into Cancer. By the third week of May, Mars is in the central part of the crab’s star pattern, near the break in its upside-down, “Y”-shape. This part of Cancer is also where a cluster of stars called the Beehive is found. As a result, Mars will appear to make some dramatically close encounters with the stars of this cluster. These planet-star meetings will be visible through binoculars.

Saturn is high above the southwestern horizon once the sky gets dark. The Ringed Planet is near Regulus, the brightest star of Leo the lion and the one that designates its heart. Saturn will not be near Regulus again until the year 2036.

May will be a great time to view Saturn through a telescope. Its rings are currently in view, but by summer, the rings will start tilting edgewise toward us. We will not have as good a view of the ring surface again until 2010.

Mercury makes its best appearance in the evening sky for this year during the second week of May. Search for it with binoculars above the west-northwestern horizon less than an hour after the sun has set.

Categories: Life and Arts

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