Monday, Nov. 10,2008, the NASA Phoenix Mars Lander mission officially ended. Its conclusion marked the accomplishment of man sending a spacecraft to the north pole of Mars. The Phoenix became the first robotic probe to test the content of Martian soil. The craft confirmed the existence of a layer of ice below the surface, but its findings about the existence of liquid water are more ambiguous. Presently, they show the present Arctic environment as being unsuitable for life as we know exists onEarth.
The NASA Phoenix Mars Lander successfully landed north of the Arctic circle of Mars May 25 after being launched in early August last year. Originally planned for a 3-month mission, it was into its fifth month of operation when NASA lost contact with the spacecraft Nov. 2. Scientists had expected the spacecraft to fail as the Martian winter approached due to the freezing temperatures and shortened hours of daylight. Less sunlight meant less power from the craft’s solar panels. Eventually, the craft would be unable to charge itself and would go into a sleep mode. It is not likely to wake up though, since the harsh winter will likely freeze and shatter the components ofthe craft.
The Phoenix madethe discovery of falling snow on the planet. Snow was detected by a laserinstrument to fall from clouds about 2.5 miles above the craft’s landing site. However,the snow was observed to evaporate before reaching the ground.
Tests of the Martian soil showed the presence of calcium carbonate. The Phoenix, equipped with a long robotic arm, dug trenches into the Martian landscape and retrieved samples of soil. The soil was then placed in small ovens for analysis. After analysis, results showed the presence of calcium carbonate as well as small claylike particles. The temperature at which carbon dioxide was released from the soil corresponded to that of the decomposition of calcium carbonate, and a buffering effect corresponded to that of calcium carbonate as well. Since calcium carbonate on Earth usually forms in the presence of liquid water, this suggested a source of liquid water.
Meanwhile, the Phoenix also used a small probe to directly test the presence of water of the soil. Looking like a cartridge with needles pointing out of it, this probe had the ability to detect water films as thin as one molecule by monitoring the movement of electricity from one needle to the next. However, when stuck into the soil, it yielded negative results, indicating a very dry Martian soil.
Yet other tests told otherwise. A test of relative humidity showed a range of 0-100%, suggesting a large moisture flow. In addition, the soil from the ground was found to pack less tightly after being exposed to the air for a day or two, and the small probe also confirmed a hard layer of ice about 2 inches below the surface. These results are suggestive of water moisture in the soil, so the dryness of the soil becomes a mystery.
As it stands, the finding of calcium carbonate and the test of relative humidity are only circumstantial evidence for the presence of liquid water. Phoenix did not detect liquid water in the soil, only solid ice. The absence of liquid water would indicate the lack of a substance that is the sustenance and lifeblood of organisms on Earth. Will water in its liquid form one day be found on Mars? That is a quest left to the next NASA mission, Mars Science Laboratory.
Sources:
http://www.nasa.gov/mission_pages/phoenix/news/phoenix-20080929.html
http://www.nasa.gov/mission_pages/phoenix/news/phoenix20080904.html
http://ap.google.com/article/ALeqM5j1hvRUNc9W-3lupLU6TLQtR0gdRAD94CDR480
http://www.jpl.nasa.gov/news/phoenix/release.php?ArticleID=1936
http://www.nytimes.com/2008/09/30/science/space130marsw.html?_r=1&fta=y