Mission to Mars: Project Based Learning Benchmark Lessons Dr

Home , Climate of Mars, Mission to Mars

Mission to Mars: Project Based Learning Benchmark Lessons Dr. Anthony Petrosino, Department of Curriculum and Instruction, College of Education, University of Texas at Austin Benchmarks content author: Elisabeth Ambrose, Department of Astronomy, University of Texas at Austin Project funded by the Center for Instructional Technologies, University of Texas at Austin

http://www.edb.utexas.edu/missiontomars/bench/bench.html

Table of Contents

Mars as a Solar System Body 4

Place in the Solar System 4

Physical Properties and Composition 5

The Moons of Mars 7

Mars geography 8

Mountains 10

Volcanoes 10

Valleys 11

Craters 12

Surface Rocks 14

Crust Composition 16

Atmosphere composition 17

Ice caps 17

Conditions on Mars 18

Gravity 18

Atmosphere 18

Weather, winds, storms 19

Temperatures, seasons, climate 20

Length of year 22

Length of day 22

Water on Mars 22

2 Polar Ice Caps 22

Water channels 23

Surface Water 25

Previous, Current, and Future Missions to Mars 25

Mariner 4 25

Mariner 6-7 26

Mariner 9 26

Viking 1-2 27

Mars Pathfinder/Sojurner Rover 27

Mars Global Surveyor 28

2001 Mars Odyssey 29

2003 Mars Exploration Rovers 29

2005 Mars Reconnaissance Orbiter 30

Smart Lander and Long-Range Rover 30

Scout Missions 31

Sample Return and Other Missions 31

Getting to Mars 31

Escape velocity 31

Routes and travel time 33

Supplies: food, water, oxygen 35

Psychological needs/concerns 35

References 40

Mars as a Solar System Body

Place in the Solar System

Sun and planets. NASA/JPL.

This picture depicts the four gas

The Solar System. NASA/JPL. giant planets (Jupiter, Saturn, Uranus, This picture depicts the correct and Neptune), Earth, and the Sun. Earth relative sizes of the 9 planets of the Solar is the tiny dot between Jupiter and the System in the correct order. The planets Sun. The relative sizes of the objects are Mercury, Venus, Earth, Mars, Jupiter, are to scale, with 3200 km corresponding Saturn, Uranus, Neptune, and Pluto. to one pixel of the image. Mars is the fourth planet from the Sun. It If the relative sizes of the planets is one of the four inner planets. Mars were shrunk to be one billionth of its orbits at a distance of 1.52 Astronomical actual size, the Earth would be the size Units (227,940,000 km) from the Sun. of a large marble (2 cm diameter), Mars One Astronomical Unit is equal to 1.496 would be the size of a pea (1 cm x 108 km, the average distance from the diameter), Jupiter would be the size of a Earth to the Sun. Astronomical Units are grapefruit, Saturn would be the size of an abbreviated A.U. Its orbit is situated orange, Uranus and Neptune would each between those of Earth and the Asteroid be the size of lemons, and the Sun would Belt. be the size of a tall man.

Climate Orbiter was approaching the

planet, shows the brightly lit side of Mars

that is facing the Sun.

The relative sizes of the Mercury, Venus, Earth, and Mars. NASA/JPL. Physical Properties and Composition While it is easy to compare the Mars has a mass of 6.4x1023 kg, relative sizes of the planets in an image, or about 100 times less than the mass of it is more difficult to compare their Earth. It has a diameter of 6,000 km, or relative distances from the Sun. If the about half that of Earth. The surface Solar System was shrunk to one billionth area of Mars is about the same as the of its actual size, the Moon would be land area of Earth. There is no evidence about 30 centimeters away from the of current plate tectonic activity or active Earth. The Sun would be 150 meters volcanism on Mars, although there is (one and a half football fields) away from evidence to suggest that such the Earth. Mars would be 325 meters phenomena have been present in the away (three football fields), Jupiter would past. Mars is made of an inner core with be 750 meters away (5 city blocks), a 1700 km radius, a molten mantle, and Saturn would be 1500 meters away (10 a very thin crust that ranges from 80 km city blocks), and the nearest star would to 30 km thick in places. The planet is be more than 40,000 km away (twice the made mostly of iron. In fact, iron oxide circumference of the Earth!) (rust) on the surface of Mars is what From the Earth, Mars looks like a makes the so-called “Red Planet” appear big, reddish star. A somewhat closer red. view as in this image taken as the Mars

greenhouse effect that raises the

temperature on the planet about five

degrees. The atmosphere is thick

enough to produce very large dust

storms that can be seen from Earth.

The interior of Mars. NASA/JPL.

A dust devil on Mars, taken by the Mars The surface of Mars. NASA/JPL. Global Surveyor. NASA/JPL.

Because Mars is not very massive, it can retain only a thin atmosphere of mostly carbon dioxide.

Carbon dioxide makes up 95.3 percent of the atmosphere, while nitrogen at 2.7 percent, argon at 1.6 percent, oxygen at

0.15 percent, and water at 0.03 percent make up the remainder. The carbon A Martian sunset, taken by the Imager for Mars Pathfinder. NASA/JPL. dioxide on Mars does produce a small

The red and blue colors in this the moon is only 22 km. It is very odd-

Martian sunset are caused by absorption shaped, and has a mass of just 1.1x1016 and scattering of light by dust in the kg. It is composed mostly of carbon-rich atmosphere. rock and is heavily cratered. Most

Mars also has ice caps on both its astronomers think that Phobos is a north and south poles. The ice caps captured asteroid. grow and shrink with the seasons, and Phobos orbits Mars very quickly. they are made of both carbon dioxide ice It usually rises, transverses the Martian

(“dry ice”) and water ice. The ice caps sky, and sets twice every Martian day. can be seen from Earth. The moon is also very close to Mars’

surface. Just as an airplane flying over

the Earth’s equator cannot be seen

above the horizon for an observer in the

United States, Phobos is so close to

Mars’ surface that it cannot be seen

above the horizon from all points on

Martian North Polar Cap. NASA/JPL. Mars. As it orbits, it slowly spirals in

towards the Martian surface. Phobos The Moons of Mars looses 1.8 meters of altitude per century, Mars has two moons named and in 50 million years it will either crash Phobos and Deimos, Greek for fear and into the surface or be destroyed in the panic. Phobos is the closer of the two, atmosphere. orbiting Mars 9378 km above the planet’s center. It is very small – the diameter of

Deimos, taken from the Viking 2 Orbiter.

Phobos taken from the Viking 1 Orbiter. NASA/JPL. NASA/JPL. Mars Geography Deimos orbits farther out than Like Earth, the surface of Mars Phobos, and it is even smaller, with a has many kinds of landforms. Some of diameter of only 12.6 km and a mass of Mars’ spectacular features include 1.8E15 kg. In fact, Deimos is the Olympus Mons, the largest mountain in smallest known moon in the Solar the Solar System. The Tharsis Bulge is System. Like Phobos, Deimos is made a huge bulge on the Martian surface that of mostly cratered carbon-rich rock, is is about 4000 km across and 10 km high. very amorphous, and is thought to be a The Hellas Planitia is an impact crater in captured asteroid. Like our own Moon, the southern hemisphere over 6 km deep Deimos orbits far enough away from and 2000 km in diameter. And the Valles Mars that it is being slowly pushed Marineris, the dark gash in Mars’ surface farther and farther away from the planet. shown in the picture below, is a system

of canyons 4000 km long and from 2 to 7 km deep.

Martian Topography. NASA/JPL.

This is a map of Martian

topography. In the left image, the

Mars, taken by the Hubble Space Telescope. NASA/JPL. Tharsis Bulge can be seen in red and The white patches in the map of white. The Valles Marineris is the long the Martian surface shown below are blue gash through the middle. In the clouds and storms in Mars’ atmosphere. right image, the blue spot is the Hellas

impact basin. Craters can also be seen

in the right image.

Mars with clouds and storms, taken by the Hubble Space Telescope. NASA/JPL.

Mars Topography. NASA/JPL.

This image is a flat map of Mars,

made from data from an instrument

aboard the Mars Global Surveyor. There

are striking differences between the Mountains northern and southern hemispheres. The picture below shows the

The northern hemisphere (top) is Libya Montes, examples of mountains on relatively young lowlands. It is about 2 Mars. The Libya Montes were formed by billion years old. The southern a giant impact. The mountains and hemisphere (bottom) consists of ancient valleys were subsequently modified and and heavily cratered highlands, much eroded by other processes, including like the surface of the Moon. It is about 4 wind, impact cratering, and flow of liquid billion years old. There is a very clean water to make the many small valleys boundary between the two regions, that can be seen running northward in although the reason for this sharp break the scene. This picture covers nearly is unknown. It might be due to a very 122,000 square kilometers (47,000 large impact that occurred just after the square miles). planet’s formation. The Hellas impact basin is visible as the bright blue region on the left side of the image. The

Tharsis Bulge is the bright red region on the right side. It is interesting to note that Mountains on Mars. NASA/JPL. these two features are located on exact Volcanoes opposite sides of the planet from each There is no known current active other. Olympus Mons is the white spot volcanism on Mars. All of the volcanoes to the left of the Tharsis Bulge. on Mars appear to be extinct. Mars also

lacks plate tectonics. Both volcanic and

plate tectonic activity are caused by heat Mons erupted was about one billion flowing from the interior of a planet years ago. toward the surface. Because Mars is much smaller than the Earth (about half its diameter), and is much less massive

(about 1/10 the mass of Earth), the

Olympus Mons. NASA/JPL. planet cooled off very quickly. There is no more heat to escape from the interior of the planet, and therefore all plate tectonic and volcanic activity has stopped. Oblique view of Olympus Mons. NASA/JPL.

The best known volcano on Mars is Olympus Mons, which is the largest volcano in the Solar System. It is a shield volcano, meaning that it has broad, gentle slopes that were formed from the eruption of lava. It rises 24 km

(78,000 ft.) above the surrounding plains

– much higher than Mt. Everest here on Elevation of Olympus Mons. Earth. Its base is more than 700 km in diameter, which is bigger than the state Valleys The following picture is an image of Missouri. It is rimmed by a cliff 6 km of the Valles Marineris, the great canyon (20,000 ft) high. The last time Olympus of Mars. It is like a giant version of the

Grand Canyon. The image shows the the same rate of cratering, but because entire canyon system, which is over of erosion, the craters have different

3,000 km long, stretching over about appearances on each surface. Because one-third of the planet. The canyon the Moon has little to no atmosphere, averages 8 km deep and might have most craters there look as fresh as the formed from a combination of plate day they were made. Mars does support tectonics and erosion. Several craters a thin atmosphere, so some erosion of are also visible around the canyon. craters there does take place. However,

the extent of this erosion is very small

compared to the erosion of craters that

happens on Earth.

Valles Marineris. NASA/JPL.

Oblique view of the Valles Marineris. NASA/JPL.

Craters

Like the Earth and the Moon, Craters on Mars. NASA/JPL.

Mars also has impact craters. All three Earth: This crater was created by a bodies have experienced approximately comet or asteroid that hit the Earth

several hundred million years ago. It is located in the Sahara Desert in Chad, and it is about 17 km wide. Erosion of the crater is clearly visible.

Crater on Mars. NASA/JPL.

Moon: These craters on the Moon are

Crater on Earth. NASA/JPL. located near the Sea of Tranquility.

Mars: This crater is located on the Craters on the Moon show very little surface of Mars. While not as eroded as erosion because the Moon has very little the craters on Earth, the rim of the crater atmosphere. has been sculpted by ice that forms on the ground.

Craters on the Moon. NASA/JPL.

Surface rocks

In this image of the Martian surface taken by the Imager for Mars

Pathfinder, the colors have been exaggerated to help show differences among the rocks and soils. It is clear

Rocks on the surface of Mars. NASA/JPL. from the image that there are three different types of rocks. The white The following images of rocks on the arrows point to flat white rocks of surface of Mars were taken by the unknown age. The red arrows point to cameras aboard the Mars Pathfinder. large rounded rocks that show weathering on their surfaces, and so have probably been at the site for some time. The blue arrows point to smaller, angular rocks. These rocks have not Rocks on the surface of Mars. NASA/JPL. been weathered, and so are thought to have been deposited or placed at this site recently, possibly by an asteroid impact.

Rocks on the surface of Mars. NASA/JPL.

Rocks on the surface of Mars. NASA/JPL. Rocks on the surface of Mars. NASA/JPL.

Rocks on the surface of Mars. NASA/JPL.

Crust composition Rocks on the surface of Mars. NASA/JPL.

Mars' crust varies in thickness

across the planet. In the northern

hemisphere, the crust is only about 35

km thick, while in the southern

hemisphere, it is about 80 km thick. This

is probably caused by a period of uneven

Rocks on the surface of Mars. NASA/JPL. cooling that the planet experienced. For

unknown reasons, Mars’ Northern

Hemisphere cooled more slowly than the

Southern Hemisphere, causing it to form

a smoother, thinner crust in that area.

This image shows a possible

configuration of soil and ice in the first

Rocks on the surface of Mars. NASA/JPL. three feet of the surface of Mars.

Soil composition on Mars. NASA/JPL.

Atmosphere composition Clouds in the Martian atmosphere. Mars’ atmosphere is composed NASA/JPL. mostly of carbon dioxide, which accounts for 96% of the total. The rest of the atmosphere is nitrogen, and argon, with very small amounts of oxygen. Mars has a very thin atmosphere; it is 200 times less massive than the atmosphere on

Earth. It would not be possible for people to breathe on Mars – not only is the atmosphere very, very thin, there is

Clouds and Storms on Mars. NASA/JPL. not enough oxygen. However, it is thick Ice caps enough to allow a parachute to slow an See also the benchmark lesson on Water incoming spacecraft. Mars also has on Mars. clouds and dust storms, as visible in the Mars has ice caps at both its pictures below. northern and southern poles. The ice is

water ice and carbon dioxide ice (dry Conditions on Mars ice). In ideal observing conditions, it is Gravity, etc. possible to see the Martian ice caps from The acceleration due to gravity on a backyard telescope on Earth. the surface of Mars is 3.72 m/s^2, or

about 0.38 times of Earth. The surface

magnetic field is about 800 times smaller

than that of Earth.

Atmosphere (content, density, sky

appearance)

Mars has a very thin atmosphere.

Mars with ice caps. NASA/JPL. With a mass of only about 2.4E19 grams,

it is about 200 times less massive than

In the summer, the ice caps shrink as the the atmosphere of the Earth. Of the water ice evaporates, leaving behind the entire planet, only about 4 parts out of carbon dioxide ice. 100 million are in the atmosphere. The

surface pressure on Mars due to the

atmosphere is only 7 millibars, or about

0.007 times the pressure of one

atmosphere on Earth. Mars’ atmosphere

is made up of 95.3% carbon dioxide,

2.7% nitrogen, 1.6% argon, 0.13%

oxygen, 0.07% carbon monoxide, and

Martian North Polar Ice Cap. NASA/JPL.

about 0.03% water vapor. Mars has 70 Mars can be seen in this image of dunes times more carbon dioxide than the formed on the Martian surface. The wind

Earth. that formed these dunes was blowing

It would not be possible for a from the bottom left to the top right of the person to survive by breathing the image. The image was taken by a

Martian atmosphere. The atmosphere is camera on the Mars Global Surveyor, too thin and does not contain enough and is about 3 km wide. oxygen to sustain human life. Any Unlike Earth, it does not rain on astronauts present on the surface would Mars. It is possible for clouds to form in need life support equipment such as the thin atmosphere, but temperatures space suits to survive. Space suits are too low to allow liquid water to form. would also protect the astronauts from However, water ice fog is often created harmful radiation that can reach the in the bottoms of Martian canyons in surface through the thin atmosphere, and early morning, and frost can form in from the extremely cold temperatures. many places on the surface.

Sunset on Mars. NASA, JPL.

Weather, winds, storms

Storms and carbon dioxide clouds do form on Mars. Evidence of winds on

Martian sand dunes. NASA/JPL. travels very high in the sky during this

time, and the number of daylight hours Temperatures, seasons, climate per day is increased. With longer days The average surface temperature and more direct sunlight, the northern on Mars ranges from 180 to 270 K, or – hemisphere is heated, causing summer. 93 degrees C to –3 degrees C (-135 At the same time, the opposite is true for degrees F to 26 degrees F). Daytime the southern hemisphere. That part of temperatures range from 216-226 K (-57 the Earth receives the least amount of to -47 degrees C, or –71 to –53 degrees direct rays of sunlight, the sun is very low F), and nighttime temperatures range in the sky, and the days are very short. from 153-208 K (-120 to –65 degrees C, This causes the southern hemisphere to or –184 to –85 degrees F). experience winter. Like Earth, Mars experiences Conversely, when the north pole changes of seasons. On any planet, of the Earth’s axis is pointing away from changes of season are caused by the tilt the Sun, the northern hemisphere of the planet’s axis. As a result of a receives the least direct rays of sunlight. planet’s axial tilt, the north pole of a The Sun travels is very low in the sky planet’s axis points toward the Sun at during this time, and the number of times in its orbit around the Sun, and at daylight hours per day is decreased. other times, it points away from the Sun. With shorter days and less direct As an example, when the north sunlight, the northern hemisphere is pole of Earth’s axis is pointing toward the cooled, causing winter. At the same Sun, the northern hemisphere receives time, the opposite is true for the southern the most direct rays of sunlight. The Sun

hemisphere. That part of the Earth because Mars’ axis is tilted by 23.98 receives the most amounts of direct rays degrees. of sunlight, the sun is very high in the On Earth, the axial tilt is the only sky, and the days are very long. This reason we have seasons. The Earth’s causes the southern hemisphere to orbit is very nearly circular, so the experience summer. seasons are not influenced by the small

amount that the Earth is closer to or

farther from the Sun over the course of a

year. (If Earth’s distance from the Sun

was what caused the seasons, the entire

Earth would experience the same

season at the same time, which, of

The axial tilt of a planet causes seasons. course, isn’t true!)

The length and severity of Seasons on Mars are a little more seasons on a planet are determined by complicated. Mars has a more elliptical the amount of the planet’s axial tilt. A orbit than Earth, so the small amount that planet with no axial tilt would have no the planet is closer to or farther from the seasons, while one with a 90 degree Sun over the course of a year do make a axial tilt (such as Uranus!) would have difference in the amount of sunlight that very extreme seasons. Seasons on reaches Mars. However, for the most

Earth are moderate because Earth’s axis part, the seasons are caused by the tilt of is tilted by 23.45 degrees. Mars has Mars’ axis. seasons that are very similar to Earth’s

In terms of Mars’ climate history, on Mars: seasonal ice caps and residual

Mars is much colder now than it was in ice caps. Seasonal ice caps accumulate its early days. More than 2 billion years during the winter season, and evaporate ago, Mars was much warmer, and during the summer. The residual caps consequently, wetter. remain during the entire year.

Length of year

It takes Mars 1.88 Earth tropical years to orbit the Sun once. This means that one year on Mars is about 687 Earth solar days long.

Length of day Martian North Polar Cap. NASA/JPL.

It takes Mars 1.026 Earth solar Mars’ seasonal ice caps are days to rotate once on its axis. This entirely dry ice that is about 1 meter means that one day on Mars is about 24 thick. The southern seasonal cap hours and 37 minutes long. measures about 4000 km across when

its largest during southern winter, and

Water on Mars the northern cap measures about 3000 km across at its largest, during northern Polar Ice Caps winter. When summer temperatures rise Mars has ice caps on both its above 150K (-120 C), the ice sublimes north and south poles. The ice caps are (passes directly from the solid state into made of water ice and carbon dioxide ice the gaseous state, bypassing the liquid (dry ice). There are two kinds of ice caps state) into the atmosphere. Large

seasonal changes in the amount of channels in the ground that were formed carbon dioxide in the atmosphere cause by running water. Water existed on the large seasonal changes, up to 30% surface of Mars several billion years ago, different, in the atmospheric pressure on when the atmosphere of the planet was

Mars. thicker and the temperature was warmer.

Mars’ residual caps vary by hemisphere. The northern cap is about

1000 km across and is made of mostly water ice. In fact, it is the main repository of water on Mars. The southern cap is much smaller, only about

350 km across. It is made of carbon dioxide ice.

Water channels on Mars. NASA/JPL.

There are two kinds of channels

Martian North Polar Cap. NASA/JPL. on Mars that have been left by water

flows: runoff channels and outflow Water channels channels. Runoff channels are the While there is no running water on equivalent of dry river beds on Mars. Mars today, there is plenty of evidence They are a series of meandering, that it once existed on the surface. Most connecting pathways that are found only of this evidence is in the form of dry in the southern highlands. They, like the

southern highlands, are thought to be about 4 billion years old.

Outflow channels are channels that were created during enormous flash floods on Mars. After the time of free flowing water, when the runoff channels were formed, the climate on Mars became very cold and much of the water froze into ice caps or permafrost just below the surface. About one billion years later, volcanoes became active on the planet and melted much of the water.

The melting water cascaded to lower elevations in huge flash floods, carving outflow channels as it went. Many

Water channels on Mars. NASA/JPL. teardrop shaped “islands” were also formed in the outflow channels. When the volcanism ended, the water refroze into the conditions that exist today.

Surface Water

The sizes of the outflow channels

indicate that there was once a great deal

of water present on the surface of Mars.

While some of it has frozen out into the

northern residual ice cap, the majority of

the water is trapped just below the

surface in permafrost.

Water channels on Mars. NASA/JPL.

Soil composition on Mars. NASA/JPL.

Previous, Current, and Future Missions to Mars

Mariner 4

Mariner 4 was a small robotic

spacecraft that was sent to Mars on

November 28, 1964 to complete one

flyby. It flew over Mars in July, 1965 and

took pictures of the surface with its digital

tape recorder. The images showed

Water channels on Mars. NASA/JPL.

lunar-type impact craters. After its flyby, Mariner 9 was also a small robotic it continued in orbit around the Sun for spacecraft, and it was launched on May three years. 30, 1971. Unlike Mariner 4, 6, and 7,

which simply flew by Mars, Mariner 9 Mariner 6-7 was designed to establish an orbit Mariner 6 and Mariner 7 were around the planet. It did so successfully, identical small robotic spacecraft that and continued to orbit for almost a year. were launched on July 31, 1969 and Mariner 9 used its imaging instruments to August 5, 1969, respectively. They make a map of the entire surface of arrived at Mars at about the same time Mars. As a result, many previously and completed one flyby. Mariner 6 flew unknown features of Mars were over the Martian equator, and Mariner 7 discovered, including Olympus Mons and flew over the southern polar region. Both Valles Marineris, and dry river beds. had imaging equipment, and they sent Close up images were also taken of the back hundreds of pictures. They also two Martian moons, Phobos and Deimos. analyzed the Martian atmosphere with remote sensing equipment. The data that Mariner 6 and Mariner 7 collected confirmed that the dark lanes seen on

Mars from Earth were not canals, as was previously thought.

Mariner 9

Mariner 9. NASA/JPL.

The Viking 1 and 2 landers Viking 1-2 descended to two different parts of Mars, Viking 1 and 2 were identical but they carried out the same types of robotic spacecraft launched on August experiments. While on the ground, they 20, 1975 and September 9, 1975 performed tests of the Martian soil to respectively. They were the first man- look for signs of life. However, no such made spacecraft to land on another signs were detected. Both the landers planet. Each Viking spacecraft consisted and the orbiters sent many hundreds of of an orbiter and a lander. Each orbiter images of the surface of Mars back to and lander flew to Mars together, and Earth. then decoupled in the Martian atmosphere. The lander descended to the ground and the orbiter continued to orbit the planet. The entire mission was designed to continue for 6 weeks after landing, but all 4 components continued to be active long after this deadline had passed. The Viking 1 orbiter continued to fly over the Martian surface for a full three years, and the lander lasted 7 years on the surface of Mars. The Viking Viking Lander. NASA/JPL.

2 orbiter and lander both lasted for four Mars Pathfinder/Sojurner Rover years.

Mars Pathfinder was a robotic spacecraft that was launched on

December 4, 1996. It landed on Mars on

July 4, 1997, using a parachute and airbags to cushion the fall. Upon landing, Pathfinder unfolded its Mars Pathfinder. NASA/JPL. instruments and deployed a small mobile robot called Sojurner Rover. The lander was renamed the Carl Sagan Memorial

Station after successful setup on the

Martian surface.

Mars Pathfinder landed in an Airbags landing system for Mars Pathfinder. NASA/JPL. outflow channel littered with many different kinds of rocks. Cameras on the Mars Global Surveyor lander sent back over 16,500 images of Mars Global Surveyor is a robotic the Martian surface, and cameras on the spacecraft designed to study Mars while

Sojurner Rover sent back another 500 in a polar orbit around the planet. It was more. In addition, Pathfinder completed launched from Earth on November 7, more than 15 chemical analyses of the 1996. Mars global Surveyor completed rocks and soil, and it studied the wind its mission in January 2001, and as it is and weather of the planet. still orbiting Mars today, it is currently in

an extended mission phase. The

satellite has returned more data about

Mars than all of the previous missions to

Mars combined. It has sent back scientists determine the soil and rock thousands of images including 3-D composition, the amount of water on images of the northern polar ice cap, Mars, the history of the climate of Mars, studied the magnetic field of Mars, found and the extent of radiation on the planet. possible locations for water, and studied the Martian moons.

Mars Odyssey. NASA/JPL.

2003 Mars Exploration Rovers

Two identical rovers will be

launched between May and July 2003,

bound for Mars. The rovers will be much

like the Sojurner Rover, but they will be

much more powerful. Like Mars Mars Global Surveyor. NASA/JPL. Pathfinder, the Rovers will enter the 2001 Mars Odyssey Martian atmosphere directly, slowed by 2001 Mars Odyssey is a robotic parachutes. Then airbags will shelter the spacecraft that was launched on April 7, robots as they bounce approximately 12 2001. It is currently in orbit around Mars, times and roll to a stop. Upon landing, collecting images and data to help

the spacecraft will unfold and the Rover This robotic spacecraft, planned for will deploy. Unlike Pathfinder, the launch in 2005, will be designed to

Rovers will have all the scientific image the surface of Mars to even instruments on board, and they will be smaller scales. It will map the able to travel up to 100 yards each surface of the planet with sufficient

Martian day. With no need to return to resolution to be able to see rocks the the landing site, the Rovers will be able size of beach balls. Hopefully the to explore a comparatively large area of data it collects will allow scientists to the Martian surface. The Rovers, which understand better the location and will land in different areas on Mars, will amount of water on Mars. send back images from their cameras and data about the Martian soils, which they will be able to analyze at very small scales.

Mars Reconnaissance Orbiter. NASA/JPL. Mars Exploration Rover. NASA/JPL.

Smart Lander and Long-Range Rover 2005 Mars Reconnaissance Orbiter

The Smart Lander and Long- type of mission might be underway as

Range Rover are planned for launch by soon as 2011, but for now the first

2007. They will be designed to use a Sample Return mission is slated for new precise landing method that should 2014, and the second for 2016. allow landings in otherwise inaccessible Getting to Mars areas. The spacecraft will also be a Escape velocity laboratory for even better surface measurements.

Scout Missions

Scout Missions, which could be small airborne craft or small landers, are Launch of the Mars Pathfinder Mission. also planned for 2007 launch. They NASA/JPL. would help increase the scale of airborne observations or increase the number of The first problem facing a sites on Mars that have been visited by potential trip to Mars is leaving Earth. human spacecraft. Specifically, this problems deals with the

enormous amount of energy necessary Sample Return and Other Missions to break free from the Earth’s NASA plans many other missions gravitational field and start traveling to Mars after 2010. One type of mission towards Mars, or anywhere else in the includes a spacecraft that would land on Solar System. To find out what energy, Mars, collect samples of Martian soil, and therefore speed, is necessary to and return those samples to Earth. This

escape Earth’s gravity, let us consider Setting rmaximum = 8, which is the the energy of a rocket at Earth’s surface: condition for gravitational escape, vinitial

2 E = ½ mrocket vinitial – GMearthmrocket/Rearth becomes vescape and we have

Energy is the sum of kinetic and potential vescape = sqrt(2GMearth/Rearth). energies. Here, vinitial is the initial The same logic can be applied to any velocity, mrocket is the mass of the rocket, planet, so the equation for escape and Mearth and Rearth are the mass of the velocity can be generalized to Earth and the radius of the Earth. Now, because the energy of the rocket is vescape = sqrt(2GM/R). constant as it travels upward, we can Thus, the escape velocity from any equate the energy of the rocket at the planet depends on the mass of the surface to the energy of the rocket at its planet and the radius of the planet. For maximum altitude: example, let us assume that we have a

spacecraft on Earth that we are trying to 2 ½ mrocket vinitial – GMearth mrocket /Rearth = 2 24 ½ mvfinal – GMearth mrocket /rmaximum. send into space. Mearth = 5.98x10 kg,

6 Here, vfinal is the final velocity and rmaximum and Rearth = 6.37x10 m, so we get: is the maximum height. However, at its vescape = sqrt (2GM/R) maximum height, vfinal = 0, so the

-11 equation becomes vescape = sqrt (2(6.67x10 Nm2/kg2)(5.98x1024 kg)/(6.37x106 m))

2 4 ½ mrocket vinitial – GMearth mrocket /Rearth = – vescape = 1.12 x10 m/s, or about 11 km/s. GMearth mrocket /rmaximum. Now, let us assume astronauts have Solving for vi, we have successfully completed their mission on 2 vinitial = 2GMearth(1/Rearth – 1/ rmaximum).

Mars and need to calculate the escape spacecraft simply leaves Mars when velocity on Mars so they can travel back Earth is slightly ahead in its orbit, and

23 to Earth. Mmars = 6.42x10 kg, and Rmars spirals into Earth’s orbit, catching up with

= 3.397x106 m, so we get: the planet. In this scenario, a team

arriving on Mars would be able to spend vescape = sqrt (2GM/R) 460 days there. The entire trip would

take about two and a half years. This -11 vescape = sqrt (2(6.67x10 Nm2/kg2)(6.42x1023 kg)/(3.397x106 m)) type of route is known as a conjunction

3 vescape = 5.0 x10 m/s, or about 5 km/s. class route because the spacecraft

arrives on Mars or Earth when that Routes and travel time planet is in conjunction with where the There are many different possible other planet was when the spacecraft routes to take when sending a spacecraft left. to Mars. As each trip covers a different distance, each takes different amounts of time and fuel.

Perhaps the most familiar type of route involves sending the spacecraft out when Mars is about 45 degrees ahead of

Earth in its orbit. This happens once every 26 months. The spacecraft powers outward and catches up with The Sun, Earth, Mars configuration upon launch from Earth.

Mars in about 260 days. For the return trip, which also takes 260 days, the

would only be 30 days available to stay

on the surface of Mars.

Lower thrust rockets can also

travel to Mars using less direct means.

These types of spacecraft spiral out of

Earth’s gravitational field, and arrive at

Mars in 85 days. Part of the ship

The Sun, Earth, Mars configuration upon arrival at Mars. detaches to drop off the astronauts and

A different type of route is known their gear, and the return module as an opposition class route, which is continues to fly by the planet. The return similar in style to conjunction class module will rendezvous with Mars again routes. It is called opposition class in 131 days, allowing the astronauts to because Earth and Mars make their catch their ride home. closest approach sometime during the There are many other proposed trip. A spacecraft would have to leave ways to get astronauts to and from the

Earth when Mars was significantly ahead red planet. For example, one scenario in its orbit, and the trip would take 220 envisions astronauts launching from days. During the return trip, the Earth and landing on one of Mars’ spacecraft would spiral inside Earth’s moons. The astronauts could then set orbit and catch up to the planet from the up a base of operation from which they back. The return trip would take 290 could make many trips to the surface of days. To time the orbits correctly, there the planet. In another proposal, a space

station that acts as a permanent ferry

could be put in orbit between the two cannot. For one day on the spacecraft, planets. Smaller spacecraft could then one person typically needs 1 kg of taxi astronauts between Earth and the oxygen, 0.5 kg of dry food and 1 kg of space station and between the space whole food, 4 kg of drinking water, and station and Mars. This situation would 26 kg of wash water. Of these staples, allow many more frequent trips for many 80% of the oxygen, 80% of the drinking more travelers back and forth between water, and 90% of the wash water can the planets. be recycled. None of the food can be

recycled. For a one way flight lasting

Supplies: food, water, oxygen. 200 days, this translates to 3,440 kg of

supplies needed. Once on the surface of

Mars, oxygen and water can be

manufactured by the astronauts. Food is

therefore the only supply to bring to the

surface, and for a 600 day stay for four

people, 1,200 kg of dry food and 2,400 Freeze dried ice cream. kg of whole food will be needed. Every person on board a spacecraft bound for any Solar System Psychological needs/concerns body needs to have access to a Taking a trip to Mars would be minimum amount of food, water, and unlike anything ever experienced by other supplies. Some of these items, humans before. As they travel away at such as air and water, can be filtered and thousands of kilometers per hour in a tiny recycled, while others, such as food, capsule, the Earth would get smaller and

smaller until it was just a tiny dot. The on Earth. Environments such as that on feeling of empty space all around would board a submarine, the International be almost crushing, leaving no doubt of Space Station, or a remote scientific the tiny insignificance of the speck of a camp in Antarctica mimic the spacecraft. And how would people psychological problems that might be handle living together, cramped in a tiny present during a trip to Mars. Examples space with no escape for three years? of these psychological problems could

Communication with Earth would take include concerns about a limited amount longer and longer, eventually causing of resources, the unchanging social there to be 20 minute delays between group, social isolation, limited messages. If problems aboard the communication with the outside world, a spacecraft emerged, there would be little self-contained ecosystem, the constant or no help available from Earth. The sense of danger, physical confinement, threat of death would be woven into lack of privacy, lack of separation everything the astronauts did. A tiny hull between work and non-work, limited breach by a small meteorite or a flare opportunity for variety and change, from the Sun would pose fatal hazards limited sensory deprivation, and that the crew could not prepare for or fix. dependence on machine-dominated

What would be the psychological effects environment. of such a journey? As a specific example, travelers to

It is possible to get a glimpse of Antarctica are very cut off from the what life might be like on such a journey outside world, just as astronauts bound by looking at similar environments here for Mars would be. Neither would be

able to contact their loved ones be very worried about the supply of air whenever they wished, and both would and water. be so far removed from the recognizable On the International Space world that no trace of it would remain. Station, astronauts deal with limited

Also, people in Antarctica must be very supplies of air, water, and food every careful with their equipment, food, and day. They also live in very small supplies in order to stay alive in the quarters and must be able to cooperate bitterly cold, harsh conditions. in order to survive. These conditions

Astronauts bound for Mars would share would be very similar to those these types of concerns. However, experienced by astronauts bound for people living in Antarctica would have Mars. However, if astronauts aboard the plenty of air to breathe and plenty of ISS ever got homesick or frightened, water to drink. They would not have to they merely have radio down to Earth to bring these supplies with them or be speak with their families or friends, or to concerned that they might run out. They look out the window to see that Earth is would also have plenty of space – if one just a short flight away. In the event of a member of an Antarctica team got major disaster that threatened the lives annoyed with another, he or she would of those aboard, emergency escape have the whole continent to walk away vehicles are available to shuttle the men and be separate for a while. Astronauts, and women back to their home planets. however, would be very confined with no However, aboard spacecraft bound for escape from each other, and they would Mars, no such quick communication or

emergency ride home would exist. As

the ship got farther and farther away ship before it departed. In addition, from the Earth, radio messages would communication with the outside world take longer and longer to reach them. would be limited and delayed, resulting in

Also, the Earth itself would shrink to the only sporadic contact with the crew’s size of a tiny dot, similar to the other loved ones and friends at home. stars. No one in human history has ever Perhaps most similar would be the been so far from our home planet, and dependence on machines for life and the psychological effects of seeing Earth safety and the imminent threat of death if nearly disappear into the darkness of those machines fail. Just as all aboard space are much unknown. the submarine would be killed in the

Perhaps the best analogue event of a hull breach, or a fire, so would relating to travel to Mars would be that of all be killed in a spaceship bound for a person in a submarine. Living on a Mars. However, it is important to note submarine for an extended period of time that if a crew member became very ill or would certainly be similar to living in a if an emergency happened that was not spaceship going to Mars. In both immediate, the submarine (unlike the situations, the people on board would be spacecraft) could always return to the living in very cramped, tight quarters, and surface in a relatively short time to they would be forced to get along to secure help. survive. They would be breathing filtered In order to alleviate some of these air and drinking filtered water. All potential problems that might arise necessary food and personal supplies during a mission to Mars, studies are would have to be brought on board the being done to determine the types and

numbers of people that would best handle the enormous stress and that best get along in these types of environments. Technology is also being developed to help determine when an astronaut is in psychological distress, and to develop strategies for dealing with the distress that do not involve returning to the Earth. For example, computers can now discern the emotional inflection in a person’s voice to look for signs of emotional trouble. If the computer does find that someone is in need of help, it is programmed to suggest ways to alleviate the problem, such as recommending extra rest, extra food, or possibly medications.

The Benchmark Lessons were developed with the help of the following sources:

Alpert, Mark. “How To Go To Mars.” Scientific American, March 2000, pp. 44-51.

Bill Arnet’s “The Nine Planets” website, http://nineplanets.org

Begley, Sharon. “The Search for Life.” Newsweek, December 6, 1999, pp. 54-61.

Chaisson, Eric, and McMillan, Steve. Astronomy Today. Prentice Hall, Upper Saddle River, New Jersey, 1999.

“Cognitave States.” Discover, May 2001, pp. 35.

Hayden, Thomas. “A Message, But Still No Answers.” Newsweek, December 6, 1999, pp. 60.

JPL’s Mars for Teachers site, http://mars.jpl.nasa.gov/classroom/teachers.html

JPL’s Mars Missions website, http://mars.jpl.nasa.gov/missions/

JPL’s Planetary Photojournal, http://photojournal.jpl.nasa.gov/

Mars Pathfinder Science Results Directory, http://mars.jpl.nasa.gov/MPF/science/science-index.html

Murr, Andrew and Giles, Jeff. “The Red Planet Takes a Bow.” Newsweek, December 6, 1999, pp. 61.

The NASA Image Exchange, http://nix.nasa.gov/

NASA Goddard Space Flight Center http://svs.gsfc.nasa.gov/stories/MOLA/index.html

NASA Goddard Space Flight Center, Earth Science Gallery http://www.gsfc.nasa.gov/gsfc/newsroom/tv%20page/g00-016_earth.html

Oberg, James, and Aldrin, Buzz. “A Bus Between the Planets.” Scientific American, March 2000, pp. 58-60.

Robinson, Kim Stanley. “Why We Should Go to Mars.” Newsweek, December 6, 1999, pp. 62.

Serway, Raymond A. Principles of Physics. Saunders College Publishing, Harcourt Brace College Publishers, Austin, 1994.

Simpson, Sarah. “Staying Sane in Space.” Scientific American, March 2000, pp. 61-62.

Singer, Fred S. “To Mars By Way of Its Moons.” Scientific American, March 2000, pp. 56-57.

Weed, William Speed. “Can We Go To Mars Without Going Crazy.” Discover, May 2001, pp. 36.

Wilford, John Noble. “Photos Bolster Idea of Water, and Possibly Life, on Mars.” New York Times, 2/20/03

Yam, Philip. “Invaders from Hollywood.” Scientific American, March 2000, pp. 62-63.

Zeilik, Michael, Gregory, Stephen A., and Smith, Elske v. P. Introductory Astronomy and Astrophysics. Saunders College Publishing, Harcourt Brace Jovanovich College Publishers, Austin, 1992.

Zorpette, Glenn. “Why Go To Mars?” Scientific American, March 2000, pp. 40-43.

Zurbin, Robert. “The Mars Direct Plan.” Scientific American, March 2000, pp. 52-55.