- 4060 - MARS - the forth planet from the Sun? The Red Planet is a cold, desert world within our solar system. It has a very thin atmosphere, but the dusty, lifeless planet is far from dull. Here are some new discoveries in space exploration.
--------------------- 4060 - MARS - the forth planet from the Sun?
- Mars has some
phenomenal dust storms that can grow so large they engulf the entire planet,
temperatures can get so cold that carbon dioxide in the atmosphere condenses
directly into snow or frost, and marsquakes regularly shake things up.
Therefore, it is no surprise that this little red rock continues to intrigue
scientists and is one of the most explored bodies in the solar system.
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- Because of the Red
Planet's bloody color, the Romans named it after their god of war. In truth,
the Romans copied the ancient Greeks, who also named the planet after their god
of war, Ares.
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- The bright rust
color Mars is known for is due to iron-rich minerals in its regolith, the loose
dust and rock covering its surface. Earth's soil is a kind of regolith, too,
albeit one loaded with organic content.
The iron minerals oxidize, or rust, causing the soil to look red.
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- Mars is further
from the sun and smaller than Earth, and at least as far as we know, does not
appear to be habitable by life. We've
learned a lot about Mars from the past 30 years of lander, rover, and orbiter
missions. We have confirmed the existence of past water on the Martian surface,
that Mars was once a habitable planet, and that it once had a thicker
atmosphere than it does today.
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- Curiosity and
Perseverance missions are studying ancient habitable environments exposed on
the surface of Mars, and both missions have found evidence that the basic
ingredients that life needs to exist were present at the surface or
near-subsurface on Mars billions of years ago.
- The planet's cold,
thin atmosphere means liquid water likely cannot exist on the Martian surface
for any appreciable length of time. Features called recurring slope lineae may
have spurts of briny water flowing on the surface, but this evidence is
disputed; some scientists argue the hydrogen spotted from orbit in this region
may instead indicate briny salts. This means that although this desert planet
is just half the diameter of Earth, it has the same amount of dry land.
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- The Red Planet is
home to both the highest mountain and the deepest, longest valley in the solar
system. Olympus Mons is roughly 17 miles high, about three times as tall as
Mount Everest.
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- The Valles
Marineris system of valleys, named after the Mariner 9 probe that discovered it
in 1971, reaches as deep as 6 miles and
runs east-west for roughly 2,500 miles, about one-fifth of the distance around
Mars and close to the width of Australia.
-
- Scientists think
the Valles Marineris formed mostly by rifting of the crust as it got
stretched. Individual canyons within the
system are as much as 60 miles wide. The canyons merge in the central part of
the Valles Marineris in a region as much as 370 miles wide. Large channels
emerging from the ends of some canyons and layered sediments within suggest
that the canyons might once have been filled with liquid water.
-
- Mars also has the
largest volcanoes in the solar system, Olympus Mons is a massive volcano, about
370 miles in diameter, and wide enough to cover the state of New Mexico.
Olympus Mons is a shield volcano, with slopes that rise gradually like those of
Hawaiian volcanoes, and was created by eruptions of lava that flowed for long
distances before solidifying. Mars also has many other kinds of volcanic
landforms, from small, steep-sided cones to enormous plains coated in hardened
lava. Some minor eruptions might still occur on the planet today.
-
- Channels, valleys
and gullies are found all over Mars, and suggest that liquid water might have
flowed across the planet's surface in recent times. Some channels can be 60
miles wide and 1,200 miles long. Water may still lie in cracks and pores in
underground rock. The salty water below
the Martian surface could hold a considerable amount of oxygen, which could
support microbial life.
-
- However, the
amount of oxygen depends on temperature and pressure; temperature changes on
Mars from time to time as the tilt of its rotation axis shifts.
-
- Many regions of
Mars are flat, low-lying plains. The lowest of the northern plains are among
the flattest, smoothest places in the solar system, potentially created by water
that once flowed across the Martian surface. The northern hemisphere mostly
lies at a lower elevation than the southern hemisphere, suggesting the crust
may be thinner in the north than in the south. This difference between the
north and south might be due to a very large impact shortly after the birth of
Mars.
-
- The number of
craters on Mars varies dramatically from place to place, depending on how old
the surface is. Much of the surface of the southern hemisphere is extremely
old, and so has many craters, including the planet's largest, 1,400-mile-wide
Hellas Planitia.
-
- Some volcanoes
also have just a few craters, which suggests they erupted recently, with the
resulting lava covering up any old craters. Some craters have unusual-looking
deposits of debris around them resembling solidified mudflows, potentially
indicating that the impactor hit underground water or ice.
-
- In 2018, the
European Space Agency's Mars Express spacecraft detected what could be a slurry
of water and grains underneath icy Planum Australe. This body of water is about 12.4 miles across. Its underground location is
reminiscent of similar underground lakes in Antarctica, which have been found
to host microbes. Late in the year, Mars Express also spied a huge, icy zone in
the Red Planet's Korolev Crater
-
- The two moons of
Mars, Phobos and Deimos, were discovered by American astronomer Asaph Hall over
the course of a week in 1877. Hall had almost given up his search for a moon of
Mars, but his wife, Angelina, urged him on. He discovered Deimos the next
night, and Phobos six days after that. He named the moons after the sons of the
Greek war god Ares. Phobos means
"fear," while Deimos means "rout."
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- Both Phobos and
Deimos are apparently made of carbon-rich rock mixed with ice and are covered
in dust and loose rocks. They are tiny next to Earth's moon, and are
irregularly shaped, since they lack enough gravity to pull themselves into a
more circular form. The widest Phobos gets is about 17 miles, and the widest
Deimos gets is roughly 9 miles . (Earth's moon is 2,159 miles wide.)
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- Both Mars moons
are pockmarked with craters from meteor impacts. The surface of Phobos also
possesses an intricate pattern of grooves, which may be cracks that formed
after the impact created the moon's largest crater, a hole about 6 miles wide,
or nearly half the width of Phobos. The two Martian satellites always show the
same face to their parent planet, just as our moon does to Earth.
-
- Deimos is not as cratered
as Phobos but still contains some craters on the surface, the shallower looking
craters appear lighter in color, taking on a white/gray hue compared to the
darker orange larger/deeper craters.
-
- It is uncertain how
Phobos and Deimos were born. They may be former asteroids that were captured by
Mars' gravitational pull, or they may have formed in orbit around Mars at
roughly the same time the planet came into existence. Ultraviolet light
reflected from Phobos provides strong evidence that the moon is a captured
asteroid.
-
- Phobos is
gradually spiraling toward Mars, drawing about 6 feet closer to the Red Planet
each century. Within 50 million years, Phobos will either smash into Mars or
break up and form a ring of debris around the planet.
-
- Mars is 4,220
miles in diameter, far smaller than Earth, which is 7,926 miles wide. The Red
Planet is about 10% as massive as our home world, with a gravitational pull 38%
as strong. (A 100-pound person here on Earth would weigh just 38 pounds on
Mars, but their mass would be the same on both planets.)
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- The atmosphere of
Mars is 95.32% carbon dioxide, 2.7% nitrogen, 1.6% argon, 0.13% oxygen and
0.08% carbon monoxide, with minor amounts of water, nitrogen oxide, neon,
hydrogen-deuterium-oxygen, krypton and xenon.
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- Mars lost its
global magnetic field about 4 billion years ago, leading to the stripping of
much of its atmosphere by the solar wind. But there are regions of the planet's
crust today that can be at least 10 times more strongly magnetized than
anything measured on Earth, which suggests those regions are remnants of an
ancient global magnetic field.
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- NASA's InSight
lander has been probing the Martian interior since touching down near the
planet's equator in November 2018. InSight measures and characterizes
marsquakes, and mission team members are tracking wobbles in Mars' tilt over
time by precisely tracking the lander's position on the planet's surface.
-
- These data have
revealed key insights about Mars' internal structure. InSight team members recently estimated that
the planet's core is 1,110 to 1,300 miles wide. InSight's observations also
suggest that Mars' crust is 14 to 45 miles thick, on average, with the mantle
making up the rest of the planet's volume.
-
- For comparison,
Earth's core is about 4,400 miles wide, bigger than Mars itself, and its mantle is roughly 1,800 miles thick. Earth has two kinds of crust,
continental and oceanic, whose average thicknesses are about 25 miles and 5
miles , respectively.
-
- Mars likely has a
solid core composed of iron, nickel and sulfur. The mantle of Mars is probably
similar to Earth's in that it is composed mostly of peridotite, which is made
up primarily of silicon, oxygen, iron and magnesium. The crust is probably
largely made of the volcanic rock basalt, which is also common in the crusts of
the Earth and the moon, although some crustal rocks, especially in the northern
hemisphere, may be a form of andesite, a volcanic rock that contains more
silica than basalt does.
-
- Vast deposits of
what appear to be finely layered stacks of water ice and dust extend from the
poles to latitudes of about 80 degrees in both Martian hemispheres. These were
probably deposited by the atmosphere over long spans of time. On top of much of
these layered deposits in both hemispheres are caps of water ice that remain
frozen year-round.
-
- Additional seasonal
caps of frost appear in the wintertime. These are made of solid carbon dioxide,
also known as "dry ice," which has condensed from carbon dioxide gas
in the atmosphere. (Mars' think air is about 95% carbon dioxide by volume.) In
the deepest part of the winter, this frost can extend from the poles to
latitudes as low as 45 degrees, or halfway to the equator. The dry ice layer
appears to have a fluffy texture, like freshly fallen snow.
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- Mars is much
colder than Earth, in large part due to its greater distance from the sun. The
average temperature is about minus 80 degrees Fahrenheit, although it can vary
from minus 195 F near the poles during
the winter to as much as 70 F at midday
near the equator.
-
- The
carbon-dioxide-rich atmosphere of Mars is also about 100 times less dense than
Earth's on average, but it is nevertheless thick enough to support weather,
clouds and winds. The density of the atmosphere varies seasonally, as winter
forces carbon dioxide to freeze out of the Martian air. In the ancient past,
the atmosphere was likely significantly thicker and able to support water
flowing on the planet's surface.
-
- Over time, lighter
molecules in the Martian atmosphere escaped under pressure from the solar wind,
which affected the atmosphere because Mars does not have a global magnetic
field.
-
- NASA's Mars
Reconnaissance Orbiter found the first definitive detections of carbon-dioxide
snow clouds, making Mars the only body in the solar system known to host such
unusual winter weather. The Red Planet also causes water-ice snow to fall from
the clouds.
-
- The dust storms on
Mars are the largest in the solar system, capable of blanketing the entire Red
Planet and lasting for months. One theory as to why dust storms can grow so big
on Mars is because the airborne dust particles absorb sunlight, warming the
Martian atmosphere in their vicinity. Warm pockets of air then flow toward
colder regions, generating winds. Strong winds lift more dust off the ground,
which, in turn, heats the atmosphere, raising more wind and kicking up more
dust.
-
- These dust storms
can pose serious risks to robots on the Martian surface. NASA's Opportunity Mars rover died after
being engulfed in a giant 2018 storm, which blocked sunlight from reaching the
robot's solar panels for weeks at a time.
-
- Mars lies farther
from the sun than Earth does, so the Red Planet has a longer year 687 days compared to 365 for our home world.
The two planets have similar day lengths, however; it takes about 24 hours and
40 minutes for Mars to complete one rotation around its axis, versus 24 hours
for Earth.
-
- The axis of Mars,
like Earth's, is tilted in relation to the sun. This means that like Earth, the
amount of sunlight falling on certain parts of the Red Planet can vary widely
during the year, giving Mars seasons.
-
- Average distance
from the sun: 141,633,260 miles. By comparison: 1.524 times that of Earth.
-
- Perihelion
(closest solar approach): 128,400,000 miles. By comparison: 1.404 times that of
Earth.
-
- Aphelion
(farthest distance from the sun): 154,900,000 miles. By comparison: 1.638 times
that of Earth.
-
- The seasons that
Mars experiences are more extreme than Earth's because the Red Planet's
elliptical, oval-shaped orbit around the sun is more elongated than that of any
of the other major planets. When Mars is closest to the sun, its southern hemisphere
is tilted toward our star, giving the planet a short, warm summer, while the
northern hemisphere experiences a short, cold winter. When Mars is farthest
from the sun, the northern hemisphere is tilted toward the sun, giving it a
long, mild summer, while the southern hemisphere experiences a long, cold
winter.
-
- The tilt of the Red
Planet's axis swings wildly over time because it's not stabilized by a large
moon. This situation has led to different climates on the Martian surface
throughout its history. A 2017 study suggests that the changing tilt also
influenced the release of methane into Mars' atmosphere, causing temporary
warming periods that allowed water to flow.
-
- The first person
to observe Mars with a telescope was Galileo Galilei, in 1610. In the century
following, astronomers discovered the planet's polar ice caps. In the 19th and
20th centuries, some researchers, most famously, Percival Lowell, believed they saw a network of long, straight
canals on Mars that hinted at a possible civilization. However, these sightings
proved to be mistaken interpretations of geological features.
-
- A number of Martian
rocks have fallen to Earth over the eons, providing scientists a rare
opportunity to study pieces of Mars without having to leave our planet. One of
the most controversial finds was Allan Hills 84001, a Martian meteorite that,
according to a 1996 study, likely contains tiny fossils and other evidence of
Mars life. Other researchers cast doubt on this hypothesis, but the team behind
the famous 1996 study have held firm to their interpretation, and the debate
about ALH84001 continues today.
-
- In 2018, a
separate meteorite study found that organic molecules, the carbon-containing
building blocks of life, although not necessarily evidence of life itself, could have formed on Mars through
battery-like chemical reactions.
-
- Robotic spacecraft
began observing Mars in the 1960s, with the United States launching Mariner 4
in 1964 and Mariners 6 and 7 in 1969. Those early missions revealed Mars to be
a barren world, without any signs of the life or civilizations people such as
Lowell had imagined there. In 1971, Mariner 9 orbited Mars, mapping about 80%
of the planet and discovering its volcanoes and big canyons.
-
- NASA's Viking 1
lander touched down on the surface of Mars in 1976, pulling off the first
successful landing on the Red Planet. Its twin, Viking 2, landed six weeks
later in a different Mars region.
-
- The Viking landers
took the first close-up pictures of the Martian surface but found no strong
evidence for life. The next two craft
to successfully reach the Red Planet were Mars Pathfinder, a lander, and Mars
Global Surveyor, an orbiter, both NASA craft that launched in 1996. A small
robot onboard Pathfinder named Sojourner, the first wheeled rover ever to
explore the surface of another planet, ventured over the planet's surface,
analyzing rocks for 95 Earth days.
-
- In 2001, NASA
launched the Mars Odyssey orbiter, which discovered vast amounts of water ice beneath
the Martian surface, mostly in the upper 3 feet . It remains uncertain whether
more water lies underneath, since the probe cannot see water any deeper.
-
- In 2003, Mars
passed closer to Earth than it had anytime in the past 60,000 years. That same
year, NASA launched two golf-cart-sized rovers, nicknamed Spirit and
Opportunity, which explored different regions of the Martian surface after
touching down in January 2004. Both rovers found many signs that water once
flowed on the planet's surface.
-
- Spirit and
Opportunity were originally tasked with three-month surface missions, but both
kept roving for far longer than that. NASA didn't declare Spirit dead until
2011, and Opportunity was still going strong until that dust storm hit in
mid-2018.
-
- In 2008, NASA sent
a lander called Phoenix to the far northern plains of Mars. The robot confirmed
the presence of water ice in the near subsurface, among other finds.
-
- In 2011, NASA's
Mars Science Laboratory mission sent the Curiosity rover to investigate Mars'
past potential to host life. Not long after landing inside the Red Planet's
Gale Crater in August 2012, the car-sized robot determined that the area hosted
a long-lived, potentially habitable lake-and-stream system in the ancient past.
Curiosity has also found complex organic molecules and documented seasonal
fluctuations in methane concentrations in the atmosphere.
-
- NASA has two other
orbiters working around the planet, the Mars Reconnaissance Orbiter and MAVEN
(Mars Atmosphere and Volatile Evolution), which arrived at Mars in 2006 and
2014, respectively. The European Space Agency (ESA) also has two spacecraft
orbiting the planet: Mars Express and the Trace Gas Orbiter.
-
- In September 2014,
India's Mars Orbiter Mission also reached the Red Planet, making it the fourth
nation to successfully enter orbit around Mars.
In November 2018, NASA landed a stationary craft called Mars InSight on
the surface. InSight is investigating
Mars' internal structure and composition, primarily by measuring and
characterizing marsquakes.
-
- NASA launched the
life-hunting, sample-caching Perseverance rover in July 2020. Perseverance,
which is about the same size as Curiosity, landed on the floor of Mars' Jezero
Crater in February 2021 along with a tiny, technology-demonstrating helicopter
known as Ingenuity.
-
- As of September
2021, Ingenuity had made more than a dozen flights on Mars, showing that aerial
exploration of the planet is feasible. Perseverance documented the 4-pound
chopper's early flights, then began focusing in earnest on its own science
mission. The big rover has already collected several samples, part of a big
cache that will be brought back to Earth, perhaps as soon as 2031.
-
- July 2020 also saw
the launch of the United Arab Emirates' first Mars mission, called Hope, and
China's first fully homegrown Mars effort, Tianwen 1. The Hope orbiter arrived
at Mars in February 2021 and is studying the planet's atmosphere, weather and
climate.
-
- In late 2017, the
administration of President Donald Trump directed NASA to send people back to
the moon before going to Mars. NASA is working on this goal via a program
called Artemis, which aims to establish a sustainable, long-term human presence
on and around the moon by the late 2020s. The lessons and skills learned from
this lunar effort will help pave the way for putting boots on Mars.
-
- With current
rocket technology, it would take at least six months for people to travel to
Mars. Red Planet explorers would therefore be exposed for long stretches to
deep-space radiation and to microgravity, which has devastating effects on the
human body. Performing activities in the moderate gravity on Mars could prove
extremely difficult after many months in microgravity. Research into the
effects of microgravity continues on the International Space Station.
-
- NASA isn't the
only entity with crewed Mars aspirations.
Elon Musk, the founder and CEO of SpaceX, has long stressed that he
established the company back in 2002 primarily to help humanity settle the Red
Planet. SpaceX is currently developing and testing a fully reusable deep-space
transportation system called Starship, which Musk believes is the breakthrough
needed to get people to Mars at long last.
-
-
June 19, 2023 MARS
- the forth planet from the Sun? 4060
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