Chapter 10 Mars
what is the borealis basin?
large region around the north pole.. may be the result of one of the largest known impacts in the solar system. basin could have formed when the largest asteroid, ceres struck the planet a grazing blow 3 billion yrs ago. collision could also explain why northern hemisphere of mars is so much lower than and differs than the south.
What is the orbital properties of mars?
Mars is the 4th planet from the sun and outermost of the 4 terrestrial worlds in the solar system. It lies outside Earth's orbits. Because of its superior/ exterior orbit, Mars appears in the sky close to sun (conjunction) and away (opposition). From Earth, Mars appears to traverse a circle in the sky, keeping close to the ecliptic and occasionally executing retrograde loops.
what are these moons?
large rocks trapped by planet's gravity. phobos is larger, orbits at a distance of 9378km from center of planet every 459 minutes.
what causes volcanoes to be so high?
planet's low surface gravity. law flow spreads to form a shield volcano, its eventual height depends on the mountain's ability to support its own weight. lower the gravity=less weight and the higher is the mountain.
what are the core of mars composed of?
planetary scientists suspect the core to be composed of large iron sulfide
Does mars have oceans?
the hellas basin is a possible candidate for ancient ocean.
what are the evidence of past running water?
the surface cracks in the tharsis region-- runoff channels and outflow channels
what is the major geological feature of mars?
the tharsis bulge-- roughly size of n. america. lies on northern equator and rises 10km higher than the rest of the surface. to its east is chryse planitia, plains of gold and west is isidis planitia, plains of isis.
how many moons does it have?
unlike mercury and venus, mars has 2 small moons that orbit around it. both visible through telescope from earth named phobos-fear and deimos-panic.
why are there no evidence of small impact craters?
unlike venus thick atmosphere, small meteoroids can penetrate mars surface. but the atmosphere is an erosive agent, transporting dust from place to place. it erases small impact craters faster than they can form.
what do the dark markings represent?
used to be thought as martian life digging irrigation canals. but actually it is highly cratered and eroded areas around which surface dust occasionally blows. the repeated covering and uncovering of these landmarks gives impression of surface change but its just the dust that covers it changing.
do these volcanoes associate with plate motion?
No like maxwell mons on venus, they are shield volcanoes sitting atop a hot spot in the underlying martian mantle. all 4 show lava channels and other flow features similar to those found on earth.
When is Mars largest and brightest in sky?
at opposition, when earth lies between mars and the sun.
what is the radius of mars?
3400km
how much is mars surface gravity compared to earth
40% that of earth, so volcanoes rise 2.5 times higher
What is Mar's orbital eccentricity?
0.093, much larger than that of most other planets. Because of this large eccentricity, Mar's perihelion distance from sun is 1.38AU, substantially smaller than its aphelion distance 1.67AU. This results i a large variation in the amount of sunlight striking the planet over the course of a year. It will also have an effect on climate.
what is the mass of mars?
0.11 times that of earth. average density is 3900 kg/m3, only slighter greater than that of the moon
what is the erosion rate of mars than on earth?
100 times slower than on earth, but still faster than on the moon or venus.
3.5 billion yrs ago, martian atmosphere was
20 times denser than it is today
How bright is mars?
bright and easily seen with naked at. at opposition, the planet is still fainter than Venus though. 3 factors, 1, mars is more than twice as far from the sun as venus. each square meter on the surface receives less than 1/4 the amount of sunlight that strikes venus. 2, mars surface area is about 30% that of venus so there are fewer surface area to intercept light. last, mars is much less reflective than venus.. only 15% of light is reflected back into space compared to venus 70%.
what are seasonal cap composed of?
carbon dioxide. temperatures never greater than 150 K or -120* C.. point at which dry ice forms. during summer, sunlight striking a cap is most intense causing carbon dioxide to evaporate and cap shrinks. in winter, atmospheric carbon dioxide refreezes and cap forms
what happens when caps freeze and shrink
causes variations in atmospheric pressure up to 30%. large fraction of the planet's atmosphere freezes out and evaporates again each year.
the two parts of martial polar caps
composed of carbon dioxide frost-dry. has 2 parts seasonal cap and residual cap.
what is the hellas basin
diametrically opposite of tharsis in the southern highlands. its the lowest point on mars. 3000km across.. formation of the basin must've caused a major redistribution of the martian crust. basin has heavily cratered floors that indicate the impact occurred very early on in history 4 billion years ago.
what is mar's most striking feature
difference between its northern and southern hemisphere. northern hemisphere: large rolling volcanic plains like lunar maria, key to identification as lava flow features. it is much larger to those of earth or moon, lava plains were formed by eruptions of large volumes of material. also has blocks of volcanic rocks with boulders blasted out of impact areas by infalling meteoroid. southern hemisphere: heavily catered highlands lying 5km above the level of the lowland north. northern plains are less cratered than the southern highlands.. also suggest northern surface is younger. 3 billion compared to the 4 billion years in south southern planes could also be the original crust of the planet
explain water creation on mars throughout history
early: conditions on planet was much warmer, perhaps earth like. liquid water was widespread forming the runoff channels as rainfall drained into river valleys. 4 billion years ago: water began to freeze because of climatic change forming the permafrost and drying out the riverbeds. mars remained frozen for 1 billion year. then volcanic activity or meterotic impact formed the notehrn lowlands. it heated large regions of the surace melting the subsurface ice, causing flashflood that created the outflow chennels. when it subsided, water refroze and mars once again became dry.
what is the martian grand canyon?
feature associated with the tharsis bulge is a great canyon known as valles marineris or the mariner valley. not a canyon in real sense because running water did not form it but astronomers think it was formed by the same crustal forces that caused the entire tharsis region to bulge outward, making the surface split and crack. what are these cracks called? tectonic fractures.. found around the tharsis bulge.
what are the runoff channels?
found in southern highlands, bearing strong resemblance to river systems on earth. geologist think its dried-up beds of long-gone rivers that once carried water on mars from the mountains down into the valleys. often referred to as valley networks. astronomers debate the creation of water-- could be part of planet water cycle in which rain fell forming rivers that drained into lakes or ocean, which evaporated to form clouds and more rain. scientists believed mars could've had rivers, lakes and oceans 4 billion years ago. possibly even life. this was when the atmosphere was thicker, the surface warmer and liquid water spread. further evidence of warm weather above freezing is discovery of clay all across southern highlands. points to liquid surface as well
what are the polar caps composed of?
frozen carbon dioxide, ie dry ice. not water ice like earth's north and south poles. polar caps do contain water but it is permanently frozen
does mars have tectonic plates?
like venus, it doesn't. absence of fault lines means the continent of tharsis is not drifting as the continents on earth. tharsis is also less heavily cratered than the northern plains, making it the youngest region on the planet 2-4 billion years old.
what are the martian surface like?
many different features- huge volcanoes, deep canyons, vast dune fields and many other wonders .. allows for current search of water on or inside surface
contribution of mars global surveyor
mapped out the martian surface to an accuracy of a few meters using laser altimeter. it analyzes pulses of laser light to measure the distance between the spacecraft and the planet's surface.
what are impacting craters?
mariner spacecraft found that surface of mars and its two moons are pitted with impact craters formed by meteoroids falling in from space
Mars today vs back then
mars today is dry and desolate but astronomers believe it was not always the case. has hints that water might've grazed surface. how do we know? the low rate of surface erosion on mars means that many surface features formed billions of years ago are still detectable. this allows astronomer to probe the surface of it to see if theirs water throughout the entire span of martian history.
polar cap characteristics
most obvious features when view from earth. it grows and diminishes according to the seasons. almost disappearing at the time of martian summer. dark surfaces of mars also change from season to season although it has little to do with the melting polar ice caps.
is there liquid water on mars today?
no- however the appearance of martian impact craters leads scientists to think that there is a layer of permafrost, or water ice, just a few meters under the surface. the ejecta blanket on mars gives the impression of a liquid that has been splashed or flowed out of a crater in 2002 mars odysessy, mars express and mars reconnaissance observer reported glacial melts and ice crystals
what is the largest volcano of all
olympus mos, northwest of tharsis. measures 700km in diameter at its base, slightly smaller than the state of texas and rises to a height of 25km above the surrounding plains.
how does mars rotate?
once on its axis every 24.6 hours making a martian day similar to that of earth. planet's equator is inclined at an angel of 24.0*, similar to earths 23.5*.
what did the mars global surveyor show?
possible data that proves mars never had oceansn. also chemical analyses by martian landers indicate that the surface contains too few carbonate rock layers--compounds containing carbon and oxygen that should have been formed in abundance of oceans. evidence supports a cold dry mars that never experienced the warm mild period required to form lakes and oceans. BUT Mars Express orbiter reinforced this theory by discovering hydrated chemical compounds in surface rocks suggesting regions were wet for along time.
the surface dust on mars is prone to
reach strong hurricane like winds
through a large telescope, mars appears as?
reddish disk with some light and dark patches and prominent polar caps. polar caps are most obvious martial surface features when viewed from earth.
what is the outflow channel?
relics of more recent flooding on mars. appear only in equatorial regions and do not form the extensive networks that characterize runoff chanel. path of flashflood of water running from southern highlands into the northern plains. flow rate must've been big, 100 times greater than the 10 tons per second y the amazon river- largest river on earth.
What are the intervals of opposition?
roughly 780-day intervals.. opposition near martial perihelion are less frequent, occurring once every 15 years. on average, earth and mars come within 0.38AU of one another only about 3 times per century.
are the martian shield volcanoes still active?
scientists found no evidence for recent eruptions but volcanoes have been around since tharsis uplift (formation of the bulge), active as recent as 100 million yrs ago by estimate of caters on slope. some may still be intermittently active.. millions of yrs may pass between eruptions
what is the season cap and residual cap
seasonal cap grows and shrinks each year, residual cap remains permanently frozen. polar caps grow larger because during the southern winter, mars is farther from the sun than half a year later in northern winter. thus the southern winter season is longer and colder than that of the north, allowing polar cap to grow larger
where did all the water on mars go?
some of it may have entered the atmosphere and escaped into space but most of it today is locked inn the permafrost layer under the surface, which a little more contained in the polar caps.
what is the largest crack?
valles marineris. cracks can be at least 2 billion years old, age for valles marineris up to 3.5 billion years. valles marineris runs for 4000kkm along the martian equator, about 1/5 of the way around the planet. valles marineris is so large that grand canon can fit in it and even seen on earth. thought to be one of the few canals observed in 19th century.
how much volcanoes do mars have altogether?
viking and mars global surveyor images reveals hundreds of volcanoes. most of the largest associate with tharsis bulge but smaller are found in northern plains.
Martian Landers
viking landers: performed chemical analyses of martian regolith. important discovery: high iron content of the planet's surface. chemical reactions between iron rich surface soil and oxygen in the atmosphere creates iron oxide "rust". gives mars its color. mars pathfinder: performed measurements of martian atmosphere and atmospheric dust while its robot rover sojourner carried out chemical analysis of the soil and rocks. took 16,000 images to earth. found rounded pebbles suggesting erosive actions and running water in past.
What happens to mars at opposition?
when mars is closest to us and most easily observed, we see it as full. Sunlight strikes surface vertically casting few shadows and preventing us from seeing any detail such as craters or mountains.
Does mars have seasonal changes?
yes, just like earth. seasons are more complicated though by variations in solar heating due to planet's eccentric orbit--southern summer occurs around the time of martial perihelion, and a lot warmer than summer in north.
do mars have volcano?
yes- contains the largest known volcanoes in the solar system. 3 very large ones are found on the tharsis bulge