Transcript Sept 2013 NASA STEMx

“MARS: NOT WHAT IT
USED TO BE”
Georgia NASA STEM Day
September 28, 2013
Nancy Sills
[email protected]
Elementary Georgia Performance Standards
3rd 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 liquid
liquid to gas
gas to liquid
liquid to solid
Identify 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/steam
liquid
ice
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 Earth’s 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 Earth’s atmosphere.
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:
Planetary Magnetism
How crucial is a planet’s magnetic field?
Relative sizes of
Earth and Mars
Shape of their
magnetic fields
Earth
Mars
Mars’s crust has small pockets with magnetic fields.
The rest is unprotected many harmful effects from the Sun.
Magnetized rocks in the crust create these fields
All of Earth is protected by a very
strong and global magnetic field
Where does Earth’s magnetic field come from?
It’s complicated, but simply
put: its outer core. Movement
of electrically conducting fluid
creates the geodynamo.
Earth
A global magnetic
field helps to
protect a planet’s
atmosphere from
the harmful effects
of the Sun’s
magnetic field and
solar wind.
Mars
So where did Mars’s atmosphere go?
We think that magnetism has a lot to do
with it, but we still don’t completely
understand
How is NASA continuing to
study this?...
The 2013 Mars Atmosphere and
Volatile EvolutioN (MAVEN) Mission
The
End
Unless you really want to know
more….
Science Summary
Mars’s atmosphere is cold and dry today, but
There was once liquid water flowing over the
surface.
Where did the water and early atmosphere go?
Ancient
Valleys
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.
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.
Other science
content relevant
Ionosphere: Ultraviolet (UV) and Extreme Ultraviolet
(EUV) light from the Sun strips off electrons from the
to MAVEN
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.
Ionosphere
Oxygen atoms, O + EUV-> Oxygen Ions, O+
+ eCO2 atoms + EUV -> CO+ + O + eCarbon atoms, C + EUV -> C+ + eHelium atoms, He + EUV -> He++ + e… etc
MAVEN Science Questions
1. What is the current state of the upper atmosphere?
2. What is the escape rate at the current epoch and how does it relate
to the controlling processes?
3. 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.
The MAVEN Spacecraft
LPW (2)
SWEA
SWIA
SEP
MAG (2)
“Gull-Wing” Solar Arrays
Fixed HGA
SEP
Articulated Payload
Platform
(IUVS/STATIC/NGIMS)
Atmosphere Escape Routes
Key:
Instruments Sample all the Relevant Physics
Atoms
 What three subatomic particles make
up atoms?
Atoms

What three subatomic particles make up
atoms?
 The subatomic particles that make up
atoms are protons, neutrons, and
electrons.
Atoms

Atoms are incredibly small.
Placed side by side, 100 million
atoms would make a row only
about 1 centimeter long—about
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 Earth’s 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.
30
Pressure Balance between Solar
Wind and Ionosphere




The solar wind exerts dynamic pressure (ρu2) 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.
31
The remaining slides illustrate some of the
technical details related to the Sun’s
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 courses…
Mars orbit
Slow solar wind
IMF
Fast solar wind
IMF
Sun
The 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 …Mars’s orbit would be close to the edge
of the images
Mars
Looking down on Mars, Sun to the left, IMF lines in the plane parallel to
page and above Mars’s “north pole” (north pole is designated by the star)
Slow solar wind
IMF moving left
to right
Mars orbit
Looking 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 right
Ion Pickup
Looking 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)
A 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
Slow solar wind IMF (lines
coming out of page
[mostly]) moving left to
right
Looking at Mars from the side, sun to the left, Mars orbit
going into page. IMF moving left to right.
Ion Pickup
As the ion spins around a magnetic field (which is moving very
quickly from left to right), the ion’s path traces out a cycloid:
http://archives.math.utk.edu/visual.calculus/0/parametric.5/
Zoomed out…
Slow solar wind IMF (lines coming out of page
[mostly]) moving left to right
Ion Pickup
Looking at the day side of Mars, Sun is directly behind you,
Mars orbit is right to left.
Same ion spins around the IMF line,
View from the Sun…
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])
Looking at Mars from the side, sun to the left, Mars orbit
going into page. IMF moving left to right.
Sputtering
(from a pickup ion)
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).
Slow solar wind IMF (lines
coming out of page [mostly])
moving left to right