Mars: Not what it used to be

Mars: Not what it used to be

Georgia NASA STEM DaySeptember 28, 2013Nancy Sills

sills-n@harris.k12.ga.usElementary Georgia Performance Standards3rd grade-S3P1. Students will investigate how heat is produced and the effects of heating and cooling, and will understand a change in temperature indicates a change in heat. d. Use thermometers to measure the changes in temperatures of water samples (hot, warm, cold) over time. Measure using thermometers the changes in temperature over time of water samples (hot, warm, and cold)4th grade S4E3. Students will differentiate between the states of water and how they relate to the water cycle and weather. a. Demonstrate how water changes states from solid (ice) to liquid (water) to gas (water vapor/steam) and changes from gas to liquid to solid. b. Identify the temperatures at which water becomes a solid and at which water becomes a gas. Demonstrate how water changes states, such as: solid to liquidliquid to gasgas to liquid liquid to solidIdentify the temperature at which water becomes a solid and at which water becomes a gas.5th grade S5P2. Students will explain the difference between a physical change and a chemical change. b. Recognize that the changes in state of water (water vapor/steam, liquid, ice) are due to temperature differences and are examples of physical change. c. Investigate the properties of a substance before, during, and after a chemical reaction to find evidence of change. Explain that temperature differences can cause a physical change/change of state in water, such as:water vapor/steamliquidice

6th grade Georgia Performance Standards

S6E3. Students will recognize the significant role of water in earth processes. a. Explain that a large portion of the Earths surface is water, consisting of oceans, rivers, lakes, underground water, and ice.

S6E1. Students will explore current scientific views of the universe and how those views evolved. c. Compare and contrast the planets in terms of Size relative to the earth Surface and atmospheric features Relative distance from the sun Ability to support life f. Describe the characteristics of comets, asteroids, and meteors.

The atmosphere of Mars is less than 1% the thickness of Earths atmosphere. The atmosphere of Mars differs from the Earth's in many ways, and most of them don't bode well for humans living there. It's composed mostly of carbon dioxide (95.3 percent compared to less than 1 percent on Earth). Mars has much less nitrogen (2.7 percent compared to 78 percent on Earth). It has very little oxygen (0.13 percent compared to 21 percent on Earth). The red planet has about 1/1000 as much water vapor (0.03 percent). It exerts only 7 millibars of pressure (Earth's atmospheric pressure is 1,000 millibars).4

Many scientists think that Mars might have had a stronger global magnetic field billions of years ago, when water once flowed on its surface. It may have looked like this:There is a growing body of evidence showing that Mars once had a much thicker atmosphere with a lot of flowing water. One of the leading theories about where that atmosphere went involves Mars having, and then losing, a strong global magnetic field.5Planetary MagnetismHow crucial is a planets magnetic field?

Relative sizes of Earth and MarsEarthMarsShape of their magnetic fieldsEarths global magnetic field is very strong compared to Marss small crustal fields.7

Marss crust has small pockets with magnetic fields.The rest is unprotected many harmful effects from the Sun.Magnetized rocks in the crust create these fieldsMost of the crustal magnetic fields are located on one half of Mars, in the southern hemisphere. Much of the northern hemisphere has little no magnetic fields.8All of Earth is protected by a very strong and global magnetic field

Earths magnetic field extends far out into space, way above its atmosphere, including the ionosphere.9

Where does Earths magnetic field come from?Its complicated, but simply put: its outer core. Movement of electrically conducting fluid creates the geodynamo.There are three requisites for a geodynamo to operate:1) An electrically conductive fluid medium,2) Kinetic energy provided by planetary rotation,3) An internal energy source to drive convective motions within the fluid.

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A global magnetic field helps to protect a planets atmosphere from the harmful effects of the Suns magnetic field and solar wind.Earth MarsThere are many processes that can strip a planets atmosphere. The process weve just been learning about is called ion pickup but there are others. A strong magnet field can shield a planet from many of these processes.11

How is NASA continuing to study this?...So where did Marss atmosphere go?We think that magnetism has a lot to do with it, but we still dont completely understand

The 2013 Mars Atmosphere and Volatile EvolutioN (MAVEN) MissionThe Mars Atmosphere and Volatile Evolution Mission (MAVEN), set to launch in 2013, will explore the planets upper atmosphere, ionosphere and interactions with the sun and solar wind. Scientists will use MAVEN data to determine the role that loss of volatile compounds, such as CO2, N2, and H2O, from the Mars atmosphere to space has played over time, giving insight into the history of Mars atmosphere and climate, liquid water, and planetary habitability. http://lasp.colorado.edu/home/maven/

14The EndUnless you really want to know more.Marss atmosphere is cold and dry today, butThere was once liquid water flowing over the surface.Where did the water and early atmosphere go?

Where's the greenhouse atmosphere that allowed water to be liquid at the surface? H2O and CO2 can go into the crust or be lost to space. MAVEN will focus on the loss to space.Science Summary

Turn-off of the Martian magnetic field allowed turn-on of solar-extreme ultraviolet (EUV) and solar-wind stripping of the atmosphere approximately 3.7-4.1 billion years ago, resulting in the present thin, cold atmosphere.

Ancient Valleys16Other science content relevant to MAVENIonosphere: Ultraviolet (UV) and Extreme Ultraviolet (EUV) light from the Sun strips off electrons from the atoms and molecules in atmospheres (ionizes the atoms and molecules), leaving many ions and electrons. UV and EUV light also breaks apart molecules. This mixture of the upper neutral atmosphere and ions and electrons is called the ionosphere. Charged particles from the solar wind (mostly electrons and protons) also ionize Mars atmosphere.

Oxygen atoms, O + EUV-> Oxygen Ions, O+ + e-CO2 atoms + EUV -> CO+ + O + e-Carbon atoms, C + EUV -> C+ + e-Helium atoms, He + EUV -> He++ + e- etcIonosphere17MAVEN Science Questions

What is the current state of the upper atmosphere?What is the escape rate at the current epoch and how does it relate to the controlling processes?What has the total loss to space been over time?MAVEN will answer questions about the history of Martian volatiles and atmosphere and help us to understand the nature of planetary habitability.18The MAVEN Spacecraft

MAG (2)Gull-Wing Solar ArraysLPW (2)SWEAArticulated Payload Platform (IUVS/STATIC/NGIMS)Fixed HGASWIASEPSEP19Atmosphere Escape Routes

Key:20There are a lot of ways that Marss atmosphere can escape to space. Many of them are related to magnetism (black, yellow, and red), but not all of them.

Instruments Sample all the Relevant PhysicsMAVENs instruments studies all of these processes.21AtomsWhat three subatomic particles make up atoms?

AtomsWhat three subatomic particles make up atoms?

The subatomic particles that make up atoms are protons, neutrons, and electrons.

AtomsAtoms are incredibly small. Placed side by side, 100 million atoms would make a row only about 1 centimeter longabout the width of your little finger!

The subatomic particles that make up atoms are protons, neutrons, and electrons.

The subatomic particles in a carbon atom are shown.

Protons and Neutrons Protons and neutrons have about the same mass.

Protons are positively charged particles (+) and neutrons carry no charge at all.

Strong forces bind protons and neutrons together to form the nucleus, at the center of the atom.

Electrons The electron is a negatively charged particle () with only 1/1840 the mass of a proton.

Electrons are in constant motion in the space surrounding the nucleus. They are attracted to the positively charged nucleus but remain outside the nucleus because of the energy of their motion.

Electrons Because atoms have equal numbers of electrons and protons, their positive and negative charges balance out, and atoms themselves are electrically neutral. The carbon atom shown has 6 protons and 6 electrons.An atom that loses electrons becomes positively charged. An atom that gains electrons has a negative charge. These positively and negatively charged atoms are known as ions.Why the Ionosphere?

(+)UV light from the sun hits atoms in Earths upper atmosphere. The energy from this light knocks an electron off the atom, leaving a free electron and an Ion. This type of ionized gas is called a plasma. Unlike other gases, it can conduct an electric charge and is affected by magnetic fields. (+)

Solar Wind Interaction with a Body with an Atmosphere

The sunlight partially ionizes the dayside atmosphere. Some of this flows to night side.The solar wind is absorbed by the planetary atmosphere.If the solar wind is magnetized, it cannot immediately enter the ionosphere, so the planet becomes an obstacle to the solar wind flow.3030Pressure Balance between Solar Wind and Ionosphere

The solar wind exerts dynamic pressure (u2) plus some magnetic and thermal pressure.The ionosphere exerts thermal pressure force against the solar wind at the ionopause.The pressure at the peak of the ionosphere is generally greater than that of the solar wind.If the standoff distance is well above the collisional region, then the magnetic field will not diffuse into the ionosphere.3131The remaining slides illustrate some of the technical details related to the Suns magnetic field, how it picks up and carries an ion away from Mars, and how the same basic process can cause sputtering.

The underlying physical concepts are typically taught in college-level coursesMars orbitSlow solar wind IMFFast solar wind IMFThe interplanetary magnetic field (IMF) from the Sun moves similar to the animations shown on this webpage:http://www.swpc.noaa.gov/wmo/solar-wind.php Marss orbit would be close to the edge of the imagesSunMarsThere are lots of other related visualizations here:http://iswa.ccmc.gsfc.nasa.gov:8080/IswaSystemWebApp/

33Slow solar wind IMF moving left to rightMars orbitLooking down on Mars, Sun to the left, IMF lines in the plane parallel to page and above Marss north pole (north pole is designated by the star)Slow solar wind IMF (lines coming out of page [mostly]) moving left to rightLooking at Mars from the side, sun to the left, Mars orbit going into page. IMF moving left to right.Slow solar wind IMF (lines coming out of page [mostly]) moving left to rightLooking at Mars from the side, sun to the left, Mars orbit going into page. IMF moving left to right.Ion suddenly created, becomes swept up by the IMF (ion starts orbiting/gyrating around the field lines and get carried away by the moving IMF)Ion PickupA charged particle that is moving relative to a magnetic field (or vice versa) moves like 0:36-0:53 in this video: http://www.youtube.com/watch?v=slmV2IlluAM

Zoomed outLooking at Mars from the side, sun to the left, Mars orbit going into page. IMF moving left to right.Ion PickupAs the ion spins around a magnetic field (which is moving very quickly from left to right), the ions path traces out a cycloid: http://archives.math.utk.edu/visual.calculus/0/parametric.5/Slow solar wind IMF (lines coming out of page [mostly]) moving left to rightView from the SunLooking at the day side of Mars, Sun is directly behind you, Mars orbit is right to left.Same ion spins around the IMF line, gets carried in the direction into the page does NOT move left or right.Slow solar wind IMF (moving in the direction into page [mostly])Ion PickupSlow solar wind IMF (lines coming out of page [mostly]) moving left to rightLooking at Mars from the side, sun to the left, Mars orbit going into page. IMF moving left to right.Ion suddenly created, becomes swept up by the quickly moving IMF, then accelerates and slams into atmosphere, causing a chain reaction that sends other particles flying away (similar to billiard balls). Sputtering (from a pickup ion)