Mars

SURFACE OF MARS

Mars has a thin, almost cloudless atmosphere that permits a clear view of the Surface
•A solar day on Mars is nearly the same length as on Earth
•Mars has polar caps that expand and shrink with the seasons
•The Martian surface undergoes seasonal color changes
A few observers, in 19thcentury, reported a network of linear features called canals
•These observations, led to many speculations about Martian life
•However, it is proven that the canals are illusion
Since 1960s, Mars have been regularly visited by unmanned spacecraft and their landing modules.
•The Martian surface has numerous craters, several huge volcanoes, a vast rift valley, and dried-up riverbeds—but no canals
the largest volcano in the solar system,600 km across, 24 km above the surrounding plains, the scarps (or cliffs) 6 km high
•It was probably formed by hot-spot volcanism: magma wells up from a hot spot in a planet’s mantle over a long time, e.g., millions of years•The huge size of Olympus Mons, instead a chain, indicates the absence of planet tectonics.
Southern highlands versus northern lowlands: dichotomy–The average elevation of southern highlands is about 5 km higher than that of northern lowlands–Surface in the south is relatively older, because of numerous craters–Surface in the north is smooth and free of cratersSurface.

Water on mars:
No liquid water or rainfall on the planet’s surface today
•Liquid water once flowed on March, as evident in many surface features
•E.g., dried riverbeds on the Martian surface
•“Island”carved by flash flood
Gullies have formed by subsurface water seeping out to the surface
•Mars’s polar caps contain frozen water•The Martian polar caps expand in winter as a thin layer of frozen carbon dioxide (dry ice) is deposited from the atmosphereWater
•Frozen water is contained in polar caps•Frozen water is stored in permafrost under the Martian surface•There might be enough water to cover the planet to a depth of 500 metersWater.

Atmosphere

•The present Martian atmosphere is composed mostly of carbon dioxide.
•The atmospheric pressure on the surface is less than 1% that of the Earth and shows seasonal variations as carbon dioxide freezes onto and evaporates from the poles.
•Mars and Earth began with similar primordial atmosphere that evolved differently
–Mars has relatively weaker gravity
–Mars is geologically inactive.
•Water and carbon dioxide molecules are broken into atoms, which then escape into space, thanks to the weaker gravity of the Mars.
•This weakened the greenhouse effect, and caused the temperature to drop.
•A lower temperature caused more water vapor to condense to the surface, carrying carbon dioxide.
•This further reduced the temperature, caused a runaway icehouse effect, opposite to the runaway greenhouse effect occurred on Venus
•The remaining water is frozen underneath the surface.
•The remaining CO2is locked in the rocks; it is not recycles into the atmosphere, thanks to the inactivity.
The remaining water is frozen underneath the surface.
•The remaining CO2is locked in the rocks; it is not recycles into the atmosphere, thanks to the inactivity.
•This resulted in a thin Martian atmosphere.

History of Mars :

Information gathered from the expeditions and from the Hubble space telescope, confirmed that Mars has water. There is frost on its surface and at its polar caps. there are also small clouds in its thin atmosphere. Apparent old river beds show that Mars once had much more water.The Northern hemisphere is low-lying. Two thirds of Mars is upland in the southern hemisphere. A line of dichotomy divides the old southern cratered surface from the northern newer surface, and goes round the bulge of the volcanic area of Tharsis, the third main physical region of Mars.

The history of Mars has been divided in epochs:
1.Early Noachian up to 4.400 million years ago
2.Late Noachian to 3.800 million years ago
3.Hesperian to 3.500 million years ago
4.Early Amazonian to 2.300 million years ago
5.Middle Amazonian to 700 million years ago
6.Late Amazonian to present.

The main period of cratering stopped in the Hesperian. The rivers date from the Early to Late Noachian. There were huge floods up to the Early Amazonian with lakes and seas. What had happened in that although the small size of Mars did not enable it to hold on to a thick atmosphere for long and much water vapour, water survived as ice under the surface like permafrost. The volcanism on Tharsis caused the floods and it melted the permafrost. It can be seen that lakes and even small seas formed over 3,000 million years ago on Mars. It is possible to see the chaotic areas of terrain where this happened and water was carried in rivers into standing lakes or seas. These areas are the sites of possible early life, which is to be looked for by the next probes to Mars.

Geography of Mars

Mars' surface is covered in ancient craters, thought to have been formed by meteorite impacts over billions of years. Countless rocks of all shapes and sizes are scattered across the surface of the planet, covered in a dusty layer of rust (iron oxide). This is what gives Mars its red colour. The planet was once volcanically active and is home to the largest volcano in the Solar System - Olympus Mons. Olympus Mons is 27 kilometres (17 miles) high. In comparison, Earth's highest mountain, Mount Everest, is 8.8 kilometres (5.5 miles) high. Another feature of Mars' surface is Valles Marineris, a 4,000 kilometres (2485 miles) long canyon which stretches almost a quarter of the way around the planet. It is the largest known surface canyon in the Solar System.

Mission on mars :

A] USSR ( The Union of Soviet Socialist Republics :Russia )

Marsnik 1 (USSR, 1960),
Marsnik 2 (USSR, 1960,
Sputnik 22 (USSR 1962),
Mars 1 (USSR 1962),
Sputnik 24 (USSR, 1962),
Cosmos 419 (USSR 1971),
Mars 2 (USSR, 1971),
Mars 3 (USSR, 1971
Phobos 1 (USSR, 1988),
Phobos 2 (USSR, 1988)

B] USA (United state of America )

Mariner 3 (USA, 1964),
Mariner 4 (USA, 1964),
Zond 2 (USSR, 1964),
Zond 3 (USSR, 1965),
Mariner 6 (USA, 1969),
Mariner 7 (USA, 1969),
Mars 1969A (USSR, 1969),
Mars 1969B (USSR, 1969),
Mariner 8 (USA 1971), ),
Mariner 9 (USA, 1971),
Mars 4 (USSR, 1973),
Mars 5 (USSR, 1973),
Mars 6 (USSR, 1973),
Mars 7 (USSR, 1973),
Viking 1 (USA, 1975),
Viking 2,(USA 1975), ,
Mars Observer (USA, 1992),
Mars Global Surveyor (USA, 1996),
Mars Pathfinder (USA, 1996),
Mars Climate Orbiter (USA 1998),
Mars Polar Lander (USA, 1999),
Deep Space 2 (USA, 1999),
Spirit / MER-A (USA, 2003),
Phoenix / Mars Scout 1 (USA 2007)
2001 Mars Odyssey (USA, 2001),
MER-B (USA, 2003), Mars Reconnaisance Orbiter (USA, 2005)
Mars Science Laboratory (USA, 2009),
Mars Orbiter (USA, 2011),
Mars Scout 2 (USA, 2011 )
Mars Sample Return Lander (USA, 2014),
Mars Astrobiological Field Lab Rover (USA, 2016)
Mars Scout 3 (USA, 2018)

C] JAPAN
Nozomi (Japan, 1998),

D] EUROPE
Mars Express (Europe, 2003 - this mission included the failed Beagle lander),
ExoMars (Europe, 2013)

E] INDIA
India has sent its own firt mars orbiter named "Mangalyaan " launched on 05 Novenmber 2013 .

F] CHAINA
Chaina's had launched own mars orbiter named " rode piggyback " on a Russian spacecraft that failed to leave Earth's orbit in November 2011. The spacecraft crumbled in the atmosphere and its fragments fell into the Pacific Ocean.

Interesting Fcats about Mars :

1] The largest volcano in the Solar System is on Mars. It is called Olympus Mons.

2] Mars has polar caps like Earth, although Mars' polar caps contain mostly frozen carbon dioxide instead of frozen water.

3] Mars is believed to have had water flowing around it like Earth once. It may have had a blue sky too. However, it is unlikely that it had grass, trees and plants like Earth has now.

4] Mars has seasons like Earth. This is caused by the tilt of the planet's axis, at a similar angle to the tilt of Earth's axis.

5] The Sun appears about half the size on Mars as it does from Earth.

6] Rocks from Mars have landed on Earth from meteorite impacts blasting debris through space.