These craters are so well preserved because of the slow rate of erosion that happens on Mars. Hellas Planitia , also called the Hellas impact basin, is the largest crater on Mars. Its circumference is approximately 2, kilometers, and it is nine kilometers deep.
The largest impact event on Mars is believed to have occurred in the northern hemisphere. Though not yet confirmed to be an impact event, the current theory is that this basin was created when a Pluto-sized body collided with Mars about four billion years ago. Scientists are currently unclear on whether or not a huge impact may be responsible for the core and tectonic activity having become dormant.
The InSight Lander , which is planned for , is expected to shed some light on this and other mysteries — using a seismometer to better constrain the models of the interior. Other theories claim that Mars lower mass and chemical composition caused it to cool more rapidly than Earth.
Mars also has discernible gullies and channels on its surface, and many scientists believe that liquid water used to flow through them. By comparing them to similar features on Earth, it is believed these were were at least partially formed by water erosion. Some of these channels are quite large, reaching 2, kilometers in length and kilometers in width. Yes, Mars is much like Earth in many respects. As our exploration of the Red Planet continues, we are learning more and more about its history and evolution.
The rotation of Earth's inner core spins in a direction different from the outer core and the interaction of the two is what gives Earth it's magnetic field. This in turn protects the surface of our planet from harmful solar radiation. The Martian core, by contrast, is largely solid and does not move. As a result, the planet lacks a magnetic field and is constantly bombarded by radiation. It is speculated that this is one of the reasons why the surface has become lifeless in recent eons, despite the evidence of liquid, flowing water at one time.
Despite there being no magnetic field at present, there is evidence that Mars had a magnetic field at one time. According to data obtained by the Mars Global Surveyor, parts of the planet's crust have been magnetized in the past.
It also found evidence that would suggest that this magnetic field underwent polar reversals. This observed paleomagnetism of minerals found on the Martian surface has properties that are similar to magnetic fields detected on some of Earth's ocean floors.
These findings led to a re-examination of a theory that was originally proposed in which postulated that Mars experienced plate tectonic activity four billion years ago. This activity has since ceased to function, causing the planet's magnetic field to fade away.
Much like the core, the mantle is also dormant, with no tectonic plate action to reshape the surface or assist in removing carbon from the atmosphere. The average thickness of the planet's crust is about 50 km 31 mi , with a maximum thickness of km 78 mi. By contrast, Earth's crust averages 40 km 25 mi and is only one third as thick as Mars's, relative to the sizes of the two planets.
The crust is mainly basalt from the volcanic activity that occurred billions of years ago. Given the lightness of the dust and the high speed of the Martian winds, features on the surface can be obliterated in a relatively short time frame. Much of Mars' composition is attributed to its position relative to the Sun. Elements with comparatively low boiling points, such as chlorine, phosphorus, and sulphur, are much more common on Mars than Earth.
Scientists believe that these elements were probably removed from areas closer to the Sun by the young star's energetic solar wind. After its formation, Mars, like all the planets in the Solar System, was subjected to the so-called "Late Heavy Bombardment. The largest impact event on Mars is believed to have occurred in the northern hemisphere. This area, known as the North Polar Basin, measures some 10, km by 8, km, or roughly four times larger than the Moon's South Pole — Aitken basin, the largest impact crater yet discovered.
Though not yet confirmed to be an impact event, the current theory is that this basin was created when a Pluto-sized body collided with Mars about four billion years ago. Scientists are currently unclear on whether or not a huge impact may be responsible for the core and tectonic activity having become dormant. The InSight Lander, which is planned for , is expected to shed some light on this and other mysteries — using a seismometer to better constrain the models of the interior.
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The peak is so massive, it curves with the surface of Mars. If you stood at the outer edge of Olympus Mons, its summit would lie beyond the horizon. The gorges span about 2, miles and cut up to 4. The valleys get their name from Mariner 9, which became the first spacecraft to orbit another planet when it arrived at Mars in About 4.
The highlands of the southern hemisphere, however, are studded with many extinct volcanoes, and the crust there can get up to 62 miles thick. What happened? At some point in the distant past, the red planet gained its two small and irregularly shaped moons, Phobos and Deimos. The two lumpy worlds, discovered in , are named for the sons and chariot drivers of the god Mars in Roman mythology. How the moons formed remains unsolved. But recent models instead suggest that they could have formed from the debris flung up from Mars after a huge impact long ago.
Deimos, the smaller of the two moons, orbits Mars every 30 hours and is less than 10 miles across. Its larger sibling Phobos bears many scars, including craters and deep grooves running across its surface. Scientists have long debated what caused the grooves on Phobos. Since the s, humans have robotically explored Mars more than any other planet beyond Earth. Currently, eight missions from the U. But getting safely to the red planet is no small feat.
Of the 45 Mars missions launched since , 26 have had some component fail to leave Earth, fall silent en route, miss orbit around Mars, burn up in the atmosphere, crash on the surface, or die prematurely.
More missions are on the horizon, including some designed to help search for Martian life. NASA is building its Mars rover to cache promising samples of Martian rock that a future mission would return to Earth.
In , the European Space Agency and Roscosmos plan to launch a rover named for chemist Rosalind Franklin , whose work was crucial to deciphering the structure of DNA.
The rover will drill into Martian soil to hunt for signs of past and present life. Other countries are joining the fray, making space exploration more global in the process. In July , the United Arab Emirates is slated to launch its Hope orbiter , which will study the Martian atmosphere. Perhaps humans will one day join robots on the red planet.
NASA has stated its goal to send humans back to the moon as a stepping-stone to Mars. Will humans eventually build a scientific base on the Martian surface, like those that dot Antarctica? How will human activity affect the red planet or our searches for life there?
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