Interesting Facts About Planet Mars
by Elizabeth Howell
on February 13, 2015
The Planet Mars. Image credit: NASA
Mars is a constant point of discussion for space explorers around the
world. We’ve sent dozens of spacecraft there to study it. Some want to
land astronauts on it. The planet is just far away to make that dream
difficult, but just close enough to spark our imagination. So what are
some of the most important things to learn about the Red Planet?
1. Mars had water in the ancient past.
We’ve been debating for centuries about whether Mars had life or not. In fact, the astronomer Percival Lowell
misinterpreted observations of “canali”
— the Italian word for channels — on the planet as evidence of
alien-made canals. It turned out Lowell’s observations were hampered by
poor telescope optics of his day, and the canals he saw were optical
illusions. That said, several spacecraft have spotted other signs of
ancient water — channels grooved in the terrain and
rocks that only could have formed in the presence of water, for example.
2. Mars has frozen water today.
We’re very interested in the question of water because it implies
habitability; simply put, life as we know it is more likely to exist
with water there. In fact, the Curiosity rover’s mandate on Mars right
now is to
search for habitable environments
(in the past or present). Mars has a thin atmosphere that does not
allow water to flow or remain in large quantities on the surface, but we
know for sure that there is ice at the poles — and possibly frosty
locations elsewhere on the planet. The question is if the ice is capable
of melting enough water in the summer long enough to support any
microbes.
Mars Express Data from Mars South Pole. Credits: ESA/ Image Courtesy of F. Altieri (IFSI-INAF) and the OMEGA team
3. Mars used to have a thicker atmosphere.
For water to flow in the past, the Red Planet needs more atmosphere.
So something must have changed in the past few billion years. What? It
is thought that the Sun’s energy striking the atmosphere must have
“stripped” the lighter forms of hydrogen from the top, scattering the
molecules into space. Over long periods of time, this would lessen the
amount of atmosphere near Mars. This question is being investigated in
more detail with NASA’s
Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft.
4. Mars has some extreme highs and lows in terrain.
The surface gravity of Mars is only 37% of what you would find on
Earth, which makes it possible for volcanoes to be taller without
collapsing. This is why we have Olympus Mons, the tallest volcano known
on a planet in the Solar System. It’s 16 miles (25 kilometers) high and
its diameter is approximately the same as the state of Arizona,
according to
NASA.
But Mars also has a deep and wide canyon known as Valles Marineris,
after the spacecraft (Mariner 9) that discovered it. In some parts, the
canyon is 4 miles (7 kilometers) deep. According to
NASA, the valley is as wide as the United States and is about 20% of the Red Planet’s diameter.
Valles
Marineris as seen in this mosaic of Viking orbiter images. Noctis
Labyrinthus at the left, Melas Chasma in the middle, Hebes Chasma just
left of top center, Eos Chasma at lower right and Ganges Chasma just
above center right. Credit: NASA/JPL
5. Mars has two moons — and one of them is doomed.
The planet has two asteroid-like moons called Phobos and Deimos.
Because they have compositions that are similar to asteroids found
elsewhere in the Solar System, according to
NASA,
most scientists believe the Red Planet’s gravity snatched the moons
long ago and forced them into orbit. But in the life of the Solar
System, Phobos has a pretty short lifetime. In about 30 million to 50
million years,
Phobos is going to crash into Mars’ surface or rip apart because the tidal force of the planet will prove too much to resist.
6. We have pieces of Mars on Earth
Remember the low gravity on Mars that we talked about? In the past,
the planet has been hit by large asteroids — just like Earth. Most of
the debris fell back on the planet, but some of it was ejected into
space. That sparked an incredible journey where the debris moved around
the Solar System and in some cases, landed on Earth. The technical name
for these meteorites is called SNC (Shergottites, Nakhlites,
Chassignites — types of geologic composition). Gases trapped in some of
these meteorites has been
practically identical to what NASA’s Viking landers sampled on the Red Planet in the 1970s and 1980s.
Phobos,
the larger of Mars’ two moons, with the Stickney crater seen on the
right side. Credit: HiRISE, MRO, LPL (U. Arizona), NASA
7. Mars would kill an unprotected astronaut quickly.
There are a lot of unpleasant scenarios for somebody who took of
their helmet. First, Mars is usually pretty cold; its average
temperature is
-50 degrees Fahrenheit (-45 degrees Celsius)
at the mid-latitudes. Second, it has practically no atmosphere. The air
pressure on Mars is only 1% of what we have (on average) on the Earth’s
surface. And third, even if it did have atmosphere, the composition is
not compatible with the nitrogen-oxygen mix humans require.
Specifically, Mars has about 95% carbon dioxide, 3% nitrogen, 1.6% argon
and a few other elements in its atmosphere.
8. In the early Space Age, we thought Mars was like the moon.
The early NASA probes that flew by the Red Planet all,
coincidentally, happened to image spots on the planets that had craters.
This led some scientists to (mistakenly) believe that Mars has an
environment similar to the moon: cratered and practically unchanging.
This all changed when Mariner 9 arrived at the planet for an orbital
mission in
November 1971
and discovered the planet engulfed in a global dust storm. What’s more,
odd features were poking out above the dust — features that turned out
to be dormant volcanoes. And as mentioned earlier, Mariner 9 found the
vast Valles Marineris. It changed our view of the planet forever.
Top:
Map of methane concentrations in Autumn (first martian year observed).
Peak emissions fall over Tharsis (home to the Solar System\’s largest
volcano, Olympus Mons), the Arabia Terrae plains and the Elysium region,
also the site of volcanos. Bottom: True colour map of Mars. Credit:
NASA/Università del Salento
9. Mars has methane in its atmosphere, but we don’t know how much.
Methane can be interpreted as a sign of biological activity —
microbes emit it — or even of geologic activity. And active planets, it
is thought, are more likely to have life on them. So the question of
methane on Mars is one that scientists are trying to figure out. The
consensus? There is no consensus. Telescopic observations have had
wildly different measurements over the years, and few spacecraft have
been designed to probe for the element in detail. The Curiosity rover
has detected
tenfold spikes in methane in its area, but we don’t know where it came from and why the fluctuations are happening.
10. Mars is a popular spacecraft destination.
There have been so many spacecraft that attempted a Martian mission
that it’s hard to pick notable ones in a short article. NASA’s Vikings
were the first landers in 1976; in fact, NASA is the only agency that
has managed to land on the planet so far. Some of its other missions
include Pathfinder-Sojourner (the first lander-rover combination) in
1997, the Mars Exploration Rovers Spirit and Opportunity in 2004, and
the Curiosity rover of 2012. And this doesn’t even mention the fleet of
orbiters that have mapped Mars over the years from the Soviet Union,
NASA, the European Space Agency and India. And there are many more
spacecraft to come in the next decade.
