Table of Contents
INTRODUCTION
Tonight, if you look
up into the sky, you'll see the same bright lights that your ancestors
admired, named and used to find their way when they were lost, or
to explain unusual events in their lives. With today's technological
imaging, you can better see those stars, planets, moons, comets, meteors,
asteroids, and now even artificial satellites.
As humans, we have always strived both to increase our knowledge and
to reach out to any other life forms that may exist in our universe.
We have succeeded at doing the former, but have yet to achieve the latter.
For centuries, we explored
from the comfort of our own planet, Earth, where we could breathe air,
sit on firm land, take notes on stone, paper, or computers, and teach
others what we know through our writing and speaking. When we first
ventured out into space in the mid-20th century, we had to change the
way we gather, store, and share information. Now it would be done with
machines that help us "see" in increasingly sophisticated ways, as we
more deeply explore away from our home planet.
One
of the ways we have learned to gather new information about other planets
is to send out data-gathering instruments that could "see" in different
spectra. These instruments would have to endure the stress of leaving
the Earth's comfortable atmosphere with the thrust of a mega-ton rocket,
and continue to function under the most hostile conditions imaginable:
the cold vacuum of space, intense heat and radiation from the Sun, and
quick changes between the two as a spacecraft speeds along at thousands
of miles per hour.
EXPLORING THE SOLAR
SYSTEM
The most recent of our
instruments is MESSENGER, the MErcury Surface, Space
ENvironment, GEochemistry and Ranging mission, designed to orbit Mercury
following two reconnaissance flybys. MESSENGER will investigate the following
key science questions:
Why is Mercury so dense?
All
terrestrial planets have a dense, iron-rich core covered by a rocky
mantle, but Mercury's core is 65% of the planet - twice as much as Earth.
MESSENGER will look for clues on the planet's surface to explain this
strange phenomenon.
- What is the geologic history
of Mercury?
Mercury has some mysterious features that we can't yet
explain: Between its largest old craters are slightly younger plains.
Many scientists believe these were created by ancient lava flows,
but no one is certain. MESSENGER will send back information about
events and forces that shaped the planet's surface. Pictures of previously
unseen portions of the planet (about 50%), will also be sent back
to Earth.
- What is happening in Mercury's
core?
One of our surprises from the first mission to Mercury (Mariner
10) was that it has a global magnetic field. In fact, Mercury is the
only terrestrial planet besides Earth to have one. Mercury's magnetic
field is weak, but the fact that it exists at all raises some interesting
questions about what is happening deep inside the planet. MESSENGER
will measure Mercury's libration (the amount it "wobbles" as it spins
on its axis), and its gravitational field to tell us about the size
of the planet's core and how much of it is solid.
- What is the nature of Mercury's
magnetic field?
Earth has a "dipolar" magnetic field, meaning that
the field is shaped like that of a bar magnet, with positively and
negatively charged poles. Mercury's field is also dipolar. In contrast,
the Moon and Mars have local magnetic fields centered on different
spots. Although scientists have several theories about how much of
Mercury's field comes from such smaller local fields, they are not
certain about how those fields were formed. MESSENGER will examine
Mercury's magnetic field over four Mercurian years (each 88 Earth
days) in detail, to determine its exact strength and how its strength
varies with position and altitude. We will also learn how the magnetic
field behaves in response to solar activity.
- What are the unusual materials
at Mercury's poles?
In 1991, scientists were excited to learn from
Earth-based radar images that something inside the craters near the
poles on Mercury were strongly reflecting radar pulses. The most common
material to explain this behavior is ice … but how could ice exist
on the planet closest to the Sun? Since the planet doesn't tilt, the
poles and surrounding craters remain permanently shadowed. Scientists
hypothesized that water molecules from comets and meteorites may have
reached these cold and shadowed craters, become trapped, frozen, and
accumulated over billions of years. Others thought that water vapor
from the planet's interior may have seeped out and frozen. Today's
scientists hope that some of MESSENGER's instruments may tell us if
the polar caps are made of water ice or other materials.
- What is the nature of Mercury's
atmosphere?
Mercury is surrounded by an extremely thin layer of gas.
It is so thin that, unlike the atmospheres of Venus, Earth, and Mars,
the molecules surrounding Mercury don't collide with each other. Instead,
they bounce from place to place on the surface, almost like rubber
balls. MESSENGER will measure Mercury's atmospheric composition and
compare these data with what we learn about its surface rocks, revealing
clues as to the origin of the five different elements (hydrogen, helium,
oxygen, sodium, and potassium) known to exist in the planet's atmosphere.
We go into space, to the
Moon, and now to planets such as Mercury, even in the face of great
risk, to push the boundaries of our problem-solving beyond current limits.
We do this because the potential benefits are too great to ignore. Indeed,
it is only if we continue to explore beyond our reach that we will be
able to better address challenges that face us here on Earth.
As we identify the complex
risks that must be overcome to safely venture out into the inhospitable
vacuum of space (even in unmanned spacecraft), we work on engineering,
scientific, and communications issues that transcend the limits of a
single mission, and apply what we learn to all our information gathering,
sharing, and storage. One important issue involves developing back-up
systems to ensure that there is no loss of accumulated knowledge due
to natural or mechanical catastrophes, to human failings, to the vagaries
of unstable governments or changing religious beliefs, or to the fear
of knowledge itself. How we study and save our society's knowledge base
speaks to how we intend to teach others what we have learned.
STUDYING THE PLANET
MERCURY
The scientific work for
MESSENGER consists of identifying and applying efficient processes to
accomplish the mission, conducting experiments to test hypotheses, and
making observations. To better understand the planet Mercury, scientists
and engineers organize massive amounts of scientific information, combine
it in unique ways, and conduct precision work to build miniaturized,
powerful instruments that will yield answers to our major questions
about other worlds, and thus about our own.
For example, Mercury has an unusually
high ratio of metal to silicate. Understanding how this came to be can
provide clues to how terrestrial planets were formed. The geological evolution
of Mercury seems to be different from other planets: explanation for many
of the surface features remains uncertain, and it is not known how big
a role volcanism, for example, may have played there.
Furthermore, Mercury is
the only terrestrial planet to have a global magnetic field. Why this
is so remains a mystery, and MESSENGER is expected to help in answering
this question by determining whether Mercury has a solid or molten core.
If Mercury's core is solid, the global magnetic field must be generated
by a different mechanism from that of Earth; if at least some of the
core is molten, it remains to be explained how Mercury has avoided cooling
off as quickly as simple calculations would predict. In addition to
determining the composition of Mercury's exosphere and the source of
its volatile species, MESSENGER will also investigate whether ice exists
in Mercury's polar regions, as radar observations from Earth have suggested.
Answering these questions will provide important points of comparison
with the Earth, in determining how the processes controlling the evolution
of the two planets are the same, and how the differences have led them
down a different path to their present states.
TEACHING ABOUT
THE MESSENGER MISSION
For the purposes of teaching
about the MESSENGER spacecraft and mission design, and for making that
information relevant to the lives of young people today, we have created
an educational program which parallels the 10-year MESSENGER mission.
We start from the notion of sending a man-made probe to the closest
planet to our Sun to learn information, and we ask students to consider
the processes and manpower needed to complete such a mission.
We continue by introducing
students to different branches of science that must be studied for understanding
the data that experts retrieve from the spacecraft. These include astronomy,
physics, astrogeophysics, chemistry, astrogeochemistry, geology, astrogeology,
dynamics, electrodynamics, hydrodynamics, fluid mechanics, thermodynamics,
quantum mechanics, magnetism, meteorology, astrometeorology, optics,
and geomorphology, to name a few.
We extend beyond the sciences
to make interdisciplinary connections, including mathematics, technology,
social studies, and all aspects of literacy to strengthen students'
abilities across the curriculum, helping them discover cultural as well
as scientific understandings of planets, the Sun, and the skies.
We develop students' literacy
of science by using appropriate scientific vocabulary and concepts,
while also helping them build their literacy through science, as we
use inherently fascinating scientific phenomena as a means of promoting
reading and writing.
We launch challenges that
motivate students to build better systems, design new experiments, discover
improved ways of doing things, and observe the world around them, in
an effort to provide them the required context to best learn the skills
they will need throughout life, in all areas.
We approach science education
by asking essential questions that drive the quest for knowledge, by
giving students ample opportunities to explore situations that embody
important scientific ideas, and by encouraging them to express their
ideas about what they are exploring. Teachers are then able to choose
appropriate ways of helping students test their ideas, to discover which
ideas apply more widely and may be more scientifically-derived than
what they had previously thought.
We help teachers create
an environment conducive to Socratic dialogue so that students are active
participants in the acquisition of personal knowledge and in the construction
of a common knowledge base. To do this, we strive to provide teachers
an understanding of science so that they can recognize and promote the
small, but relevant ideas that are related to larger, more significant
theories.
We design activities that
require first-hand observations as well as in-depth study of existing
data. In both cases, students are allowed to develop ideas more fully
as they work through their own creative thinking and problem-solving,
rather than through rote memorization. It is essential that children
change their own misconceptions as a result of what they find themselves,
not merely by accepting other ideas they have been told are better than
their own.
We encourage creativity
and thinking outside the box, while making sure that national science
standards are directly addressed in every lesson. Children learn science
best through a process that helps them link ideas and develop new concepts.
We make full use of science process skills (observing, measuring, hypothesizing,
predicting, planning and carrying out investigations, interpreting,
inferring, and communicating) to help them make sense of the world around
them. In addition to traditional summative evaluations at the end of
a lesson, we offer forms of formative assessment throughout the teaching
process, so that the teacher is aware of students' evolving ideas and
skills. Furthermore, this information is an integral part of effective
teaching, since it can significantly change the direction of a given
lesson to better address problems or misconceptions that persist.
In general, we provide
a context for understanding the significance of scientific ventures
and engineering feats such as the MESSENGER mission, and we open the
door to students who will both understand and build the future.
The MESSENGER Story
The MESSENGER story, presented
in grade-appropriate ways at four different levels (Pre-K-1, 2-4, 5-8,
9-12), is told through several lessons in each of the following three
themes:
- Comparative Planetology
- By studying Mercury, we look at the diversity of worlds and add
to the knowledge base about the Solar System, its formation and evolution.
- The Solar System Through History - By studying
Mercury, we learn about scientific discoveries and cultural interpretations
from ancient civilizations to the present.
- Framing Pathways to Answers: The Scientific Process in Action
- By studying Mercury and our efforts to reach there, we define and
solve design and engineering problems, and approach scientific research
in innovative and productive ways.
Pre-K
- Grade 1
In the early elementary
grades, MESSENGER lessons focus on literacy: both in science and in
general reading/writing skills. Children are offered science content
and a context in which to practice and improve literacy skills; this
combination fosters the development of both knowledge and skills, improves
their motivation and interest in the subject area, and contributes to
their overall educational success.
While MESSENGER lessons
are fascinating science experiences, they also provide interdisciplinary
connections across the curriculum in areas other than reading and writing.
We show pathways to related subjects in all our lessons, giving children
ample opportunity to use the literacy skills they are acquiring to access
an entire academic curriculum.
The first unit is "Staying
Cool" and falls under the theme, "Framing Pathways," since one of the
first ideas we introduce in the MESSENGER educational program is the
concept of venturing into inhospitable environments to explore what
is out there, despite the risks.
Some lessons that address
this concept include: Sources of Light, Stars and the Sun,
Sources of Light, Shadows, Hot and Cold and In
Between, In the Shade - How to Stay Cool, Materials
That Protect- (Potholders, Fireman's Suit) and Design Challenge:
Keeping My Lunchbox Cool.
Grades
2-4
As children proceed through
elementary school, they require continued opportunities that allow them
to engage in scientific exploration. This will help them to connect
ideas and build concepts, while challenging old ideas and testing new
ones in light of new experiences and evidence. Once they can do this
in increasingly rigorous and reliable ways, children will be able to
improve upon their own ideas in order to better understand - and contribute
to - the world around them.
As with the other grade
levels, this one will culminate with a Design Challenge; here, students
will be asked to create some sort of solar shield to protect an object
from the harsh effects of our Sun. Leading up to that final project
will be lessons such as the following: Astronomy With a Stick: Exploring
the Sun's Movement, Heat From the Sun, Sensing Energy,
Measurement of Heat, Absorption of Heat-Explorations of
Colors and Materials, What Does Heat do to Materials?,
What are Some Cool Materials?, How Much Solar Energy Can
We Collect?
Grades
5-8
In middle school, the MESSENGER
educational program strengthens existing Earth science courses not only
with lessons in Comparative Planetology, but with lessons such as Terrarium!,
Baseball Gravity Assist, Snow Goggles and Wax
People.
To keep students interested
in science at this transitional age, we offer a large number of hands-on
activities that encourage both boys and girls in individual as well
as group discovery.
There is often a wide range
of abilities in middle school students, due in large part to the varying
quality of their elementary education, and to individual maturing differences.
We recognize teachers' need to tailor lessons to a particular population,
and we therefore provide a considerable amount of lesson adaptation
suggestions, such as for students who are learning disabled, gifted,
ESL, or have other special needs.
Grades
9-12
At the high school level,
the MESSENGER educational program offers students an overall perspective
of exploration, helping them combine fragments of accumulated knowledge
into a meaningful whole.
The MESSENGER curriculum
encourages high school students to take serious steps towards scientific
careers or at least towards a more scientific approach to everyday problems
and issues. Students will handle real data from the MESSENGER mission
as transmitted to NASA scientists, and conduct their own investigations,
analyzes, and interpretations.
Lessons include: A
Radioactive World, Composite Materials, Marble Trajectories,
Time Synchronization, Water Spectrophotometer and
Building a Model MESSENGER.
Appendix:
National Science Education Standards Relevant to MESSENGER
Unifying Concepts
and Processes
- Systems, order, and organization
- Evidence, models, and
explanation
- Change, constancy, and
measurement
- Evolution and equilibrium
- Form and function
Science as Inquiry
- Abilities to do scientific
inquiry
- Understanding about scientific
inquiry
Physical Science
(K-4) Light, heat, electricity, magnetism
- (5-8) Motions and forces
- (5-8) Transfer of energy
- (9-12) Chemical reactions
- (9-12) Motions and forces
- (9-12) Conservation of energy and increase in disorder
Life Science
- (9-12) Matter, energy, and organization in living systems
Earth and space science
- (K-4) Objects in the sky
- (5-8) Earth in the Solar
System
- (9-12) Geochemical cycles
- (9-12) Origin and evolution
of the universe
Science and technology
- (K-4) Abilities to distinguish
between natural objects and objects made by humans
- (K-12) Abilities of technological
design
- (K-12) Understanding about
science and technology
Science in personal and social perspectives
- (K-4) Changes in environments
- (5-8) Risks and benefits
- (5-8) Science and technology
in society
- (9-12) Science and technology
in local, national, and global challenges
History and nature of science
- (K-12) Science as a human
endeavor
- (5-8) Nature of science
- (5-8) History of science
- (9-12) Nature of scientific
knowledge
