Star Talk: Phoenix made the most of its 5-month life on Mars

The last month has been a tough one for the robots on Mars. NASA’s updated Mars Polar Lander mission, known as Phoenix, last communicated with Earth on Nov 2. At the same time, the Spirit rover has been left in a vulnerable state after it was caught in a Martian dust storm.

Phoenix landed in the northern plains of Mars at a location that would roughly be equivalent to Alaska on Earth. The demise of the mission, however, was anticipated because Mars has seasons similar to Earth — only twice as long. Subsequently, the sun has been making a lower path across the Martian sky each day as the northern summer season on the Red Planet now turns to autumn. With diminishing sunlight, the solar panels of Phoenix could not provide enough power for this stationary explorer to endure the increasingly severe cold and cloudy weather at its landing site.

Phoenix was rated for a nominal mission time of three months. When it landed on May 25, it set down farther north on Mars than any previous space craft had landed. During its five months of operation, Phoenix dug into the Martian surface and analyzed the soil in its eight one-time-use miniature ovens. Its analysis verified the presence of water-ice under the surface, while its cameras returned more than 25,000 images of the terrain and sky surrounding its landing site.

Phoenix performed scientific observations and investigations 98 percent of the 152 days it operated on Mars. It has advanced the understanding of the Mars arctic environment and helped determine if this region has ever been hospitable for microbes to exist.

Phoenix detected a mildly alkaline soil, found small concentrations of salts, and identified the mineral calcium carbonate that could have formed long ago in the presence of liquid water. Phoenix observed snow in the thin atmosphere of Mars and documented the humidity, pressure and temperature conditions each day at its site.

In coordination with NASA’s Mars Reconnaissance Orbiter circling above the planet, Phoenix not only performed simultaneous observations of the Martian atmosphere with the Orbiter, but its radio transmissions, supported by the orbiting spacecraft, formed a communications relay around another planet.

The next flight to Mars will take place with the coming launch of the Mars Science Laboratory. Currently scheduled to lift off during the fall of 2009, this machine will be a roving laboratory with the most advanced collection of scientific instruments ever sent to study the surface of Mars. Meanwhile, the two Mars exploration rovers, Spirit and Opportunity, continue to make tracks across the Red Planet.

Spirit lives on

Near the equator of Mars and in operation since early 2004, the Spirit Exploration Rover was caught in a dust storm during early November and its solar panels are now significantly covered with dirt, reducing the amount of power its solar cells can generate. Photographs of Spirit, taken from its imaging boom, show that the rover is so dusty that it seems to blend in with the Martian surface.

In fact, its low energy output is the smallest that Spirit, or its sister rover, Opportunity, has ever produced in the almost five Earth-years that these machines have been roaming the Red Planet.

To ensure its survival, mission controllers are turning off some of Spirit’s functions to reduce its energy demands, but there is concern that residual dust will remain on the solar panels, reducing the amount of electrical energy the rover can produce.

Ongoing Opportunity

The other Mars Exploration rover, Opportunity, has recently driven out of a crater it was exploring for the last two years. Planetary scientists want its next target to be a crater that is 20 times larger because there would be a much deeper layer of rock exposed. However, to get there, Opportunity would need to travel about seven miles from its present location. That is approximately how far it has traveled since it started roving four years ago.

Traveling at a clip of more than 100 yards a day, it would take Opportunity two years to make the journey. Nevertheless, scientists say that even if Opportunity, already far past its rated lifetime, does not survive the journey, it is headed in a scientifically interesting direction. Investigators expect younger layers of the Martian surface to be revealed along its new path.

December sky

Jupiter and Venus have been forming a planetary spectacle in the early evening sky, clearly visible in the southwest during the evening commute. The two bright planets have been closing in on one another all month and will appear closest together early tonight (Nov. 30). As a bonus, a thin lunar crescent will be to the lower right of these planets. Be sure to look before 6:30 p.m., before all three reach the horizon.

This celestial scene gets even better. A spectacular union of Jupiter, Venus, and the crescent moon will take place tomorrow evening when the three form a compact celestial group. Then, during the next few days, as the two planets stay relatively close, Venus will slowly position itself above Jupiter. Watching these ongoing sky events can be a rewarding and educational family activity.

Later in December, as Jupiter nears the horizon earlier each evening, Mercury will also come into view. These two planets will form a close pair, very near the southwestern horizon on the last day of the year.

To see the two, use binoculars and be sure to look shortly after 5:30 p.m. That same evening, the eye-catching sight of the crescent moon next to Venus will take place again.

Richard Monda is an astronomer living the Capital Region.