MARS | Space Time

MARS

Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, being only larger than Mercury. In English, Mars carries the name of the Roman god of war and is often referred to as the "Red Planet". The latter refers to the effect of the iron oxide prevalent on Mars's surface, which gives it a reddish appearance distinctive among the astronomical bodies visible to the naked eye. Mars is a terrestrial planet with a thin atmosphere, with surface features reminiscent of the impact craters of the Moon and the valleys, deserts and polar ice caps of Earth.

The days and seasons are comparable to those of Earth because the rotational period, as well as the tilt of the rotational axis relative to the ecliptic plane, is similar. Mars is the site of Olympus Mons, the largest volcano and highest known mountain on any planet in the Solar System and of Valles Marineris, one of the largest canyons in the Solar System. The smooth Borealis basin in the northern hemisphere covers 40% of the planet and maybe a giant impact feature. Mars has two moons, Phobos and Deimos, which are small and irregularly shaped. These may be captured asteroids, similar to 5261 Eureka, a Mars trojan.

Mars has been explored by unmanned spacecraft. Mariner 4, launched by NASA on 28 November 1964, was the first spacecraft to visit Mars, making its closest approach to the planet on 15 July 1965. Mariner 4 detected the weak Martian radiation belt, measured at about 0.1% that of Earth and captured the first images of another planet from deep space. On 20 July 1976, Viking 1 performed the first successful landing on the Martian surface. The Soviet Mars 3 spacecraft achieved a soft landing in December 1971 but contact was lost with its lander seconds after touchdown. On 4 July 1997, the Mars Pathfinder spacecraft landed on Mars and on 5 July released its rover, Sojourner, the first robotic rover to operate on Mars. Pathfinder was followed by the Mars Exploration Rovers, Spirit and Opportunity, which landed on Mars in January 2004 and operated until 22 March 2010 and 10 June 2018, respectively. The Mars Express orbiter, the first European Space Agency (ESA) spacecraft to visit Mars, arrived in orbit on 25 December 2003. On 24 September 2014, the Indian Space Research Organisation (ISRO) became the fourth space agency to visit Mars, when its maiden interplanetary mission, the Mars Orbiter Mission spacecraft, arrived in orbit.

INTERNAL STRUCTURE

Like Earth, Mars has differentiated into a dense metallic core overlaid by less dense materials. Current models of its interior imply a core with a radius of about 1,794 ± 65 kilometres (1,115 ± 40 mi), consisting primarily of iron and nickel with about 16–17% sulfur. This iron (II) sulfide core is thought to be twice as rich in lighter elements as Earth's. The core is surrounded by a silicate mantle that formed many of the tectonic and volcanic features on the planet, but it appears to be dormant. Besides silicon and oxygen, the most abundant elements in the Martian crust are iron, magnesium, aluminium, calcium, and potassium. The average thickness of the planet's crust is about 50 kilometres (31 mi), with a maximum thickness of 125 kilometres (78 mi). Earth's crust averages 40 kilometres (25 mi).

Mars is seismically active, with InSight recording over 450 marsquakes and related events in 2019.

ATMOSPHERE

Mars lost its magnetosphere 4 billion years ago, possibly because of numerous asteroid strikes,[ so the solar wind interacts directly with the Martian ionosphere, lowering the atmospheric density by stripping away atoms from the outer layer. Both Mars Global Surveyor and Mars Express have detected ionised atmospheric particles trailing off into space behind Mars, and this atmospheric loss is being studied by the MAVEN orbiter. Compared to Earth, the atmosphere of Mars is quite rarefied. Atmospheric pressure on the surface today ranges from a low of 30 Pa (0.030 kPa) on Olympus Mons to over 1,155 Pa (1.155 kPa) in Hellas Planitia, with a mean pressure at the surface level of 600 Pa (0.60 kPa). The highest atmospheric density on Mars is equal to that found 35 kilometres (22 mi)] above Earth's surface. The resulting mean surface pressure is only 0.6% of that of Earth (101.3 kPa). The scale height of the atmosphere is about 10.8 kilometres (6.7 mi), which is higher than Earth's, 6 kilometres (3.7 mi) because the surface gravity of Mars is only about 38% of Earth's, an effect offset by both the lower temperature and 50% higher average molecular weight of the atmosphere of Mars.

The atmosphere of Mars consists of about 96% carbon dioxide, 1.93% argon and 1.89% nitrogen along with traces of oxygen and water. The atmosphere is quite dusty, containing particulates about 1.5 µm in diameter which gives the Martian sky a tawny color when seen from the surface. It may take on a pink hue due to iron oxide particles suspended in it.

MARTIAN FACTS

Mars and Earth have approximately the same landmass.
Even though Mars has only 15% of the Earth’s volume and just over 10% of the Earth’s mass, around two-thirds of the Earth’s surface is covered in water. Martian surface gravity is only 37% of the Earth’s (meaning you could leap nearly three times higher on Mars).
Mars is home to the tallest mountain in the solar system.
Olympus Mons, a shield volcano, is 21km high and 600km in diameter. Despite having formed over billions of years, evidence from volcanic lava flows is so recent many scientists believe it could still be active.
Only 18 missions to Mars have been successful.
As of September 2014, there have been 40 missions to Mars, including orbiters, landers and rovers but not counting flybys. The most recent arrivals include the Mars Curiosity mission in 2012, the MAVEN mission, which arrived on September 22, 2014, followed by the Indian Space Research Organization’s MOM Mangalyaan orbiter, which arrived on September 24, 2014. The next missions to arrive will be the European Space Agency’s ExoMars mission, comprising an orbiter, lander, and a rover, followed by NASA’s InSight robotic lander mission, slated for launch in March 2016 and a planned arrival in September 2016.
Mars has the largest dust storms in the solar system.
They can last for months and cover the entire planet. The seasons are extreme because it's elliptical (oval-shaped) orbital path around the Sun is more elongated than most other planets in the solar system.
On Mars, the Sun appears about half the size as it does on Earth.
At the closest point to the Sun, the Martian southern hemisphere leans towards the Sun, causing a short, intensely hot summer, while the northern hemisphere endures a brief, cold winter: at its farthest point from the Sun, the Martian northern hemisphere leans towards the Sun, causing a long, mild summer, while the southern hemisphere endures a lengthy, cold winter.
Pieces of Mars have fallen to Earth.
Scientists have found tiny traces of Martian atmosphere within meteorites violently ejected from Mars, then orbiting the solar system amongst galactic debris for millions of years, before crash landing on Earth. This allowed scientists to begin studying Mars before launching space missions.
Mars takes its name from the Roman god of war.
The ancient Greeks called the planet Ares, after their god of war; the Romans then did likewise, associating the planet’s blood-red colour with Mars, their god of war. Interestingly, other ancient cultures also focused on colour – to China’s astronomers it was ‘the fire star’, whilst Egyptian priests called on ‘Her Desher’, or ‘the red one’. The red colour Mars is known for is due to the rock and dust covering its surface being rich in iron.
There are signs of liquid water on Mars.
For years Mars has been known to have water in the form of ice. The first signs of trickling water are dark stripes or stains on the crater wall and cliffs seen in satellite images. Due to Mars’ atmosphere, this water would have to be salty to prevent it from freezing or vaporising.
One day Mars will have a ring.
In the next 20-40 million years Mars’ largest moon Phobos will be torn apart by gravitational forces leading to the creation of a ring that could last up to 100 million years.
Sunsets on Mars are blue.
During the martian day, the sky is pinkish-red, this is the opposite of the Earth’s skies.