"Phoenix" died, but what gave his death?

Today, NASA has finally lost contact with the Phoenix research apparatus, which landed on Mars in May of this year. Consequently, his mission ended there.
NASA specialists have not received signals from the Phoenix since November 2, when it briefly contacted the Earth. Initially it was assumed that the device will work on the "red planet" for only three months, but it remained functional for more than five months. The short duration of the Phoenix mission is related to the fact that it worked in the northern part of Mars, where with the onset of winter the sun disappears, giving the apparatus energy.
As suggested by NASA, the death of the Phoenix was brought closer by a dust storm, which finally shielded its batteries from sunlight. Despite this, two NASA satellites, just in case, will catch signals from the Phoenix for another three weeks - until the moment when the Sun shields Mars from Earth.
What helped scientists to learn Phoenix?

• The most important achievement of the Phoenix, launched from the Florida spaceport in August 2007, was the study of ice, which was found only a few centimeters below the surface of the planet’s soil. With the help of cameras installed on the device, scientists have even seen how this ice evaporates.
• The mineral that has never been encountered on the red planet has been discovered: opal. Opal is a type of quartz and is formed in water. Until now, only two main groups of hydrates have been discovered by the orbital Martian vehicles: phyllosilicates and hydrogenated sulphates. The first clay silicates were formed 3.5 billion years ago, when hot volcanic rocks came into contact with water, and the second were formed in the next few hundred million years, as a result of the evaporation of saline and often acid water.

As for further studies of Mars, in 2009 a new rover, the Mars Science Laboratory, will land on the red planet and land in the clay-rich region of Mars.