| European Space Agency scientists had hoped that an American satellite orbiting Mars, the Mars Odyssey, would pick up a signal from the Beagle 2. Space officials believe the delay in receiving signal from the Beagle may be due to the probe requiring additional time to unfold or that the probe had landed at an unusual angle.
Mars rotates around its axis inclined to the orbital plane at an angle of 24° 56’. Period of rotation of the planet is 24 hours 37 minutes 22.7 seconds. Therefore, one Martian year consists of 668.6 Martian solar days (called sols). Inclination of the rotation axis of Mars ensures change of seasons during the year. At the same time, elongated orbit leads to significant difference in their duration. Thus, northern spring and summer, taken together, last for 371 sols, i.e. much more than half Martian year. At the same time they occur at the parts of the Martian orbit that are farthest from the Sun. Therefore, at Mars northern summers are long and cool, and at the south they are comparatively shorter and hotter.
Magnetic field:
Mars does have a magnetic field, but it is quite weak and highly unstable, its strength may vary from 1.5 to 2 times at various parts of the planet, and the magnetic poles do not coincide with the physical ones. This suggests that the iron core of Mars is comparatively immobile w.r.t to its crust, which in turn means that the mechanism of planetary dynamo, responsible for Earth’s magnetic field, does not apply to Mars. There is a theory saying that in the distant past, there may have occurred collision of Mars with a large celestial body leading to cessation of rotation of its core, as well as loss of the bulk of its atmosphere. It is believed that the magnetic field of Mars was lost about 4 billion years ago. Due to weak magnetic field, solar winds almost freely penetrate into the Martian atmosphere. Many photochemical reactions that are caused by solar radiations, which on Earth occur in ionosphere and above, can be observed almost everywhere on the surface of Mars.
Atmosphere and climate:
Temperature of the planet ranges from -153° C at the North Pole in winter and up to about +20°C at the equator at noon. The average temperature is -50°C.
Martian atmosphere, composed mainly from carbon dioxide, is very sparse. Pressure at the surface of Mars is 160 times less than that on Earth i.e. an average of 6.1 mbar. Due to huge variation in the altitudes on Mars, pressure at the surface varies significantly. Pressure is maximum - 10 -12 mbar in Hellas basin at a depth of 8 km, and it drops to 0.3 mbar at the peak of Mount Olympus (27 km above the average level). Unlike on Earth, mass of the Martian atmosphere varies significantly throughout the year due to melting and freezing of polar ice caps that contain carbon dioxide.
There is also evidence that in the past, Martian atmosphere could have been denser and its climate was warm and humid, and water existed on the surface of Mars in liquid state, and it also rained there.
Atmosphere of Mars comprises 95% carbon dioxide, and it also contains 2.7% nitrogen, 1.6% argon, 0.13% oxygen, 0.1% water vapor, and 0.07% carbon monoxide. Martian ionosphere extends from 110 to 130 km above the surface of the planet.
Observations conducted from Earth and data from spacecraft Mars Express have detected methane in the Martian atmosphere. Under the conditions prevalent on Mars, this gas rapidly decays, so there must be a constant source of replenishment. Such a source can be either geological activity (but no active volcanoes have been found on Mars), or life activity of bacteria.
Climate, as on Earth, is seasonal in nature. During cold weather, a light frost is formed on the surface even outside the polar caps. Phoenix lander once recorded snowfall however the snowflakes evaporated before reaching the surface.
According to researchers from the Carl Sagan Center, climate at Mars is currently getting warmer. Other experts believe it is too early to come to such conclusions.
Dust devils were recorded by Rover Opportunity. These air turbulences occur at the surface of planet and lift large amounts of sand and dust into the air. They are also often observed on Earth, but on Mars, they can reach much larger volumes.
Mars Surface:
Two-third of the surface of Mars is covered with bright areas, known as continents, and the remaining third part is occupied by the dark areas known as seas. Seas are concentrated mainly in the southern hemisphere, between 10 and 40° latitude. In the northern hemisphere there are only two major seas - Acidalia Planitia and Syrtis Major.
Nature of the dark areas still remains a topic of debate. They are there, despite the fact that Mars is raged by huge dust storms. It was once argued that the dark areas are covered with vegetation.
|
