Space_Exploration_student by pengtt

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```									Space Technology & Engineering

Chapter 9: Space Exploration
SECTION 1
Introduction to Astronomy
General questions for any trip
•   Where do I want to go?
•   What route will I take to get there?
•   How far is it?
•   How do I know if I’m going the right way?
•   How am I going to get there?
•   What do I need to take with me?
•   What am I going to do when I get there?
“Do you see what I see?”
• Most of what we know about the Universe comes
from use of ___________________

• Further knowledge comes from the use of robot
explorers

• At present, only a small amount of knowledge has
been gained by humans in space
Through the looking glass

• To learn about the universe through a telescope,
you must understand the following concepts:
• Nature of light
• Electromagentic spectrum
• Absorption of light and resultant Spectra
• Doppler effect
Two sides of a coin
• Light has both a particle and wave nature
– Under certain circumstances, it behaves as a particle
– Under certain circumstances, it behaves as a wave

• For this chapter, only the _________ nature will be
covered
Types of Waves
• A wave is the manner through which energy moves
through matter and space
• Mechanical waves
– Particles relay energy from one to the other
– Must have __________ present
• Electromagnetic waves
– Energy moves through interactions of _____________
and __________________ fields
– Does not need __________ present
“What’s the frequency, Kenneth?”
• One characteristic of light is its frequency

• Frequency is how many waves go be each second
– The unit of frequency is the Hertz (Hz)
2 waves per second = 2 Hz

1s    2s

1 waves per second = 1 Hz

2s
1s

½ wave per second = .5 Hz

1s    2s
“Let there be light”

• An electromagnetic wave is called light

• Light can have many frequencies

• All of light’s frequencies together are called the
__________________________________
– Includes visible light and invisible light
Electromagnetic Spectrum
GAMMA RAYS
X-RAYS
Frequency Increasing

ULTRAVIOLET
VISIBLE LIGHT

INFRARED
MICROWAVE
“I spy with my little eye”
• By using all of the wavelengths of light, we can see
things in space that we might not be able to see
normally
• Many objects in space emit light

• However, many of these objects do not emit light in
visible light wavelengths

• As they can’t be seen with the human eye, they are
invisible in the blackness of space

• These objects are called ____________ radiators
VISIBLE LIGHT   INFRARED LIGHT
Looking for prints
• When light hits matter, some of the light is
temporarily absorbed and the rest is reflected
• Every substance absorbs and reflects differently
• So, every substance gives off its specific light
“fingerprint” – called _______________
• By studying the _____________ of the light given
off by planets and stars, we can estimate what their
______________________ are
Example of a spectra “fingerprint”
Doppler effect
• When the source of the wave moves, it changes the
wave
• The wave in front of the source will bunch up
increasing the frequency
• The wave behind the source will spread out
decreasing the frequency
When car is stopped, the waves are evenly spaced

Lower frequency
Higher frequency

When car is moving, the waves more frequent in front of the car than
behind
Red and Blue states
• Everything in space is moving

• If something is moving towards us, the frequency of
its light hitting us increases
– So the frequency of light increases – called a
“__________ shift”
• If something is moving away from us, the frequency
of its light hitting us decreases
– So, the frequency of light decreases – called a
“____________ shift”
Practice
 What do mechanical waves require that electromagnetic
waves don’t?
 What is a Hz?
 List the parts of the electromagnetic spectrum from
lowest to highest frequency
 What is a blackbody radiator?
 What is a spectra?
 You are approaching an object, explain what is happening

 All practice questions are due at the end of the chapter
SECTION 2
Astronomical Coordinate Systems
Where’s Waldo?
• To plan a route, you must know where you are
• It is also helpful to have a map
• On Earth, your location is given by latitude and
longitude
• _____________ – the number of degrees from the
equator you are
• ______________ – the number of degrees from the
Prim Meridian
LONGITUDE   LATITUDE
“…as long as you know where you’ve been”
• All stars and planets also have coordinates

• These coordinates use the Earth as the reference
point

• Unlike coordinates on the Earth, coordinates in
space constantly change as everything is moving
Dividing up the sky
• On the Earth, we use the equator and the Prime
Meridian to divide the Earth up into hemispheres

• Space coordinates also use the equator and the
poles to divide up the sky into hemispheres
– The _______________ equator is right above our
equator
– The ________________ poles are right above our north
and south poles
“If I’m so inclined”
• To determine how far away from the celestial
equator an object is, an angle called
__________________ is used

• Going up from the equator gives a positive angle
(from 0° to 90° )

• Going down from the equator gives a negative
angle (from 0° to -90° )
Around the world in…

• The equivalent of longitude is called right
___________________ (RA)

• The ordinate can be given as degrees

• It is most often given in hours, minutes, and
seconds due to the Earth’s rotation
– One hour equals _________
Ecliptic
• We also use the equator of the Sun
• An imaginary line above the Sun’s equator is called
the ecliptic

• Since the Earth is tilted compared to the ecliptic,
there is an angle between the ecliptic and the
celestial equator
“Round and round she goes..”

• Earth rotates around the Sun

• Earth revolves around its axis

• Earth’s axis also moves – similar to a top
– This movement is called _________________
– It normally takes _____________ Earth years to make
one full precession
– Currently the “north star” is the star ____________
“Where in the solar system is Carmen
Sandiego?”
• As each planet takes different amounts of time to
orbit the Sun, then the distance between them
changes
– ________________– a point on the line from the Earth
toward the Sun
– ________________– a point on the line from Earth away
from the Sun
– ______________position – an orbit farther from the Sun
than Earth
– ______________position - an orbit closer to the Sun
than Earth
Practice
 Define longitude and latitude
 Define celestial equator, celestial north pole, and ecliptic
 An object has a declination of 15 degrees and right
ascension of 30 degrees. About where in the world is it
 Define precession
 A planet is in superior opposition. Where is it in relation
to the Earth?

 All practice questions are due at the end of the chapter
SECTION 3
Orbits
“Blast off”

• Before you get to space, you have to get to orbit

• To reach orbit, you must travel _____________

• To escape Earth’s orbit to go into space, you must
travel _______________ km/h (about 25,000 mph)
“It’s not flying, it’s falling…with style”
• When a rocket launches, the Earth’s gravity is trying
to pull it back
• If the rocket launches at an angle, the Earth will pull
it back a distance away from the start point
• With enough speed, the rocket can make it all the
way around
• Once this happens, it has reached a balance
between speed and gravity…orbit
Types of Orbits
 Geostationary
 Geosynchronous
 Polar
 Solar Synchronous
 Molniya
 Hohmann transfer

 Direction of orbit
 A _______________ orbit means travelling in the same
direction as the planet’s rotation
 A ________________orbit means travelling in the opposite
direction as the planet’s rotation
Geosynchronous Orbit (GEO)
Earth lasting one day.

• A spacecraft in geosynchronous orbit appears to
remain above Earth at a constant ____________,
although it may seem to wander north and south.
Geostationary Orbit

• A geosynchronous orbit is with an inclination of
either zero, right on the equator, or else low enough
that the spacecraft can use propulsive means to
constrain
• the spacecraft's apparent position is that it hangs
motionless above a point on Earth.
• This orbit is ideal for certain kinds of
communication satellites or meteorological
satellites.
Polar Orbits
 90-degree inclination orbits, useful for spacecraft that
carry out mapping or surveillance operations.
 The planet rotates below a polar orbit, allowing the
surface.
 To achieve a polar orbit at Earth requires more energy,
thus more propellant, than does a regular orbit of low
inclination.
 For a regular orbit, launch is normally accomplished near
the equator, where the rotational speed of the surface
contributes a significant part of the final speed required for
orbit.
 A polar orbit will not be able to take advantage of the "free
ride" provided by Earth's rotation, and thus the launch
vehicle must provide all of the energy for attaining orbital
speed.
Sun synchronous orbits (SSO)
• Walking orbits whose orbital plane precesses with
the same period as the planet's solar orbit period.

• In other words, an orbit can be established so that a
spacecraft can either face the day side or the night
side of a planet
Molniya orbits
• Highly eccentric Earth orbits with periods of
approximately 12 hours (2 revolutions per day).

• The orbital inclination is chosen so the rate of
change of perigee is zero, thus both apogee and
perigee can be maintained over fixed latitudes.
– This condition occurs at inclinations of 63.4 degrees and
116.6 degrees.

• This orientation can provide good ground coverage
at high northern latitudes.
Now I’m getting… perturbed?
• There are other forces acting on a satellite that
perturb it away from the nominal orbit.

• These forces result in ____________________, or
variations in the orbital elements

• Precise orbit determination requires that the
periodic variations be included as well.
Third-Body Perturbations
• The gravitational forces of the other objects can
cause periodic variations in all of the orbital
elements

• The two primary objects with this effect in Earth
orbit:
– Sun
– Moon
Perturbations due to Non-spherical Earth
 When developing the two-body equations of motion,
we assumed the Earth was a spherically symmetrical,
homogeneous mass.

 In fact, the Earth is neither homogeneous nor
spherical.

 The most dominant features are
 a bulge at the equator
 a slight pear shape
 flattening at the poles
Perturbations from Atmospheric Drag
• A spacecraft is subjected to drag forces when moving
through a planet's atmosphere.

• This drag is greatest during launch and reentry,
however, even a space vehicle in low Earth orbit
experiences some drag as it moves through the Earth's
thin upper atmosphere.

• In time, the action of drag on a space vehicle will cause
it to spiral back into the atmosphere, eventually to
disintegrate or burn up.
Hitting the brakes

• For space vehicles within 120 to 160 km of the Earth's
surface, atmospheric drag will bring it down in a few
days, with final disintegration occurring at an altitude

• Above approximately 600 km, drag is so weak that
orbits usually last more than 10 years - beyond a

• The deterioration of a spacecraft's orbit due to drag is
called _______________.
• Solar activity also has a significant affect on
atmospheric density, with high solar activity resulting in
high density.
– Below about 150 km the density is not strongly affected by
solar activity
– At satellite altitudes in the range of 500 to 800 km, the
density variations between solar maximum and solar
minimum are approximately two orders of magnitude.

• The large variations imply that satellites will decay
more rapidly during periods of solar ___________and
much more slowly during solar _____________.
Hohmann Transfer Orbit
• What happens if you want to go from one orbit to
another?
– You can’t just point upwards and fire your engines

• Instead, you change how fast you are travelling
– Increased speed will push you into a higher orbit
– Decreasing speed drops you to a lower orbit

• You are still orbiting but your new orbit is a temporary
one that will intersect with the new orbit
– Hohmann Transfer orbits are temporary
Hohman Transfer Orbit

ORIGINAL
HOHMAN

NEW ORBIT
Practice
 What speed must you reach to get to orbit? To escape
orbit?
 Briefly explain how something gets into orbit
 A sun synchronous orbit could be said to be a special kind
of what orbit?
 A ship goes into a retrograde orbit. What does that mean?
 Describe factors that can affect an orbit

 All practice questions are due at the end of the chapter
SECTION 4
Celestial Mechanics
Moving on up..
• After reaching orbit, you must determine the path
that you must take to get to your destination

• If you aim the spacecraft where a planet is, it will
never get there…..that planet is moving
– You must aim to where the planet will be

• So, that means you must know how planets move
through the solar system
Good job, Johannes
• Johannes ____________ was an astronomer who
developed rules for how planets orbit the sun

• These came to be known as:
– Law of Ellipses – the ___________ of orbits
– Law of Equal Areas – the ___________traveled in an
orbit
– Law of Periods – the __________ required to make an
orbit
Keplar’s Law of Ellipses
• All planets orbit in an ellipse

• The combined distance from the two foci to any
point on the ellipse always stays the same
An eccentric old man
• Eccentricity – means how round an ellipse is
– Related to how far apart the foci are
• Eccentricity of ______ means a perfect circle
• Eccentricity of ________ means a straight line

NOTICE THAT THE
RINGS OR SATURN
FORM AN ELLIPSE, NOT
A CIRCLE
Kelpler’s Law of Equal Areas
• Objects in an elliptical orbit cover the same amount
of area in a given time period throughout the orbit

• Elliptical orbits then mean that objects speed up
when they are close to the Sun (or whatever they
are orbiting around) and slow down when they are
farther away
Kepler’s Law of Periods
• Orbital speed depends on distance from the sun
– Predicts the distance each planet would be from the sun
(confirmed by spacecraft and other devices)
• A planet’s speed of its orbit decreases the farther
from the Sun it is
• The period (or how long it takes) of a planet’s orbit
increases the farther from the sun it is

• P2 = R3
– P = time of orbit (in years)
NAME          AVG      APPROX.       TIME OF     APPROX.
DISTANCE    DISTANCE        ORBIT      ORBIT
FROM SUN    OF ORBIT (in   (in Earth   SPEED (in
(AU)         AU)          Years)    AU/year)

Mercury    .39 AU        2.45          .24         10.2
Venus     .72 AU        4.52          .62          7.3
Earth        1          6.28           1           6.3
Mars      1.52 AU       9.55          1.88         5.1
Jupiter    5.2 AU        32.67        11.86         2.8
Saturn     9.5 AU        59.69        29.46         2.0
Uranus     19.2 AU      120.64        84.01         1.4
Neptune    30.1 AU      189.13       164.79         1.1
Pluto      39.5        248.19       248.54         1
“Which came first, the chicken..”

• Most of Kepler’s Laws seem pretty much like
common sense today

• You may ask, “Didn’t Newton predict the second
law would happen because of gravity?”
• Yes. But Kepler came up with his laws before
Newton was alive – he knew what was happening
without knowing the why
• Newton’s Law of Gravity explained the “why”
Plotting a course
• To get from Earth to another planet, you must use a
_____________________________ orbit
– This time, the transfer orbit will be an orbit around the
Sun instead of around the Earth

• To launch a spacecraft from Earth to an outer planet
such as Mars using the least propellant possible,
first consider that the spacecraft is already in solar
orbit as it sits on the launch pad.
Going round and round in circles
• This existing solar orbit must be adjusted to cause it
to take the spacecraft to Mars:

• The orbit's _______________(closest approach to
the sun) will be at the distance of Earth's orbit, and
the ________________(farthest distance from the
sun) will be at the distance of Mars' orbit.

• The portion of the solar orbit that takes the
spacecraft from Earth to Mars is called its
_____________.
“..good timing brought me to you”
• Getting to the planet Mars, rather than just to its
orbit, requires that the spacecraft be inserted into
its interplanetary trajectory at the correct time so it
will arrive at the Martian orbit when Mars will be
there.

• The opportunity to launch a spacecraft on a transfer
orbit to Mars occurs about every _______ months.
A Martian captive
• To be captured into a Martian orbit, the spacecraft
must then decelerate relative to Mars using a
______________rocket burn or some other means.

• Since Mars has an atmosphere, final deceleration
may also be performed by aerodynamic braking
direct from the interplanetary trajectory, and/or a
– _____________________________ – using the
atmosphere to slowdown
The evening “star”
• To go from Earth to an inner planet such as Venus
using least propellant, a different transfer orbit
must be used.

• To achieve this, the spacecraft lifts uses its rocket to
accelerate opposite the direction of Earth's
revolution around the sun, thereby decreasing its
orbital energy to the extent that its new orbit will
have a perihelion equal to the distance of Venus's
orbit.
The right time and place
• The spacecraft will continue going in the same
direction as Earth orbits the sun, but a little slower
now.

• To get to Venus, rather than just to its orbit, again
requires that the spacecraft be inserted into its
interplanetary trajectory at the correct time so it
will arrive at the Venusian orbit when Venus is
there.

• Venus launch opportunities occur about every 19
“Slingshot effect”
• Spacecraft can use the planets to speed up
• If a spacecraft approaches close enough to a planet,
its path will curve

• The planet is travelling much faster around the Sun
than the spacecraft
– If the spacecraft is heading in the same direction, then it
will speed up due to gravity attraction (the planet slows
down very slightly…to maintain balance)
– When the curved path arcs away from the planet, the
spaceship will have a higher speed
Hitting the gas

• In a gravity-assist trajectory, angular momentum is
transferred from the orbiting planet to a spacecraft
approaching from behind the planet in its progress

• Gravity assists can be also used to slow down a
spacecraft, by flying in front of a body in its orbit,
donating some of the spacecraft's angular
momentum to the body.
Practice
 Explain each of Kepler’s 3 Laws
 A planet has an eccentricity of .001. What does this
mean?
 A baby is born on Mars. When it celebrates its 3rd
Martian birthday, how old would it be on Earth?
 A ship leaves an asteroid near Jupiter to bring its cargo
back to Earth. Explain how it would proceed?
 How can a spacecraft get a speed boost from a
planet?

 All practice questions are due at the end of the
chapter
SECTION 5
Distances
How to measure distances

• Once you know where you are going, you next need
to determine how far away it is

• For “short distances” (less than __________ light
years) you would use a method called ___________

• For “long distances” you would a variety of
methods can be used
A shifty character

• If you hold your finger in front of your face and
close one eye and look with the other, then switch
eyes, you'll see your finger seem to "shift " with
respect to more distant objects behind it.
– The effect is called parallax.

• Astronomers can measure parallax by measuring
the position of a nearby star very carefully with
respect to more distant stars behind it
Parallax
• A ground station measures the angle to an object in
January
• It measures again in July (when it is on the other
side of the Sun)
• The angles form an arc
• The angle to the bisector is called the parallax
– There are ______ arc minutes in a degree
– There are _______ arc seconds in a arc minute
– Each arc second in the parallax equals 1 __________
(3.26 light years)
“This little light of mine”
• Most energy in the universe follow the
___________________Law

• As energy moves from its source it spreads out

• This means that there is less energy per square
meter

• A simplified version of this is: E/r2
– So, if you double the distance, energy is divided by four
– If you triple the distance, energy is divided by nine
Tripping the lights fantastic

• We can measure the amount of light reaching the
Earth from the Sun and other known stars

• We can then measure the light from stars far away
to determine the distance

• Before we can finish, we must know how much light
it started with
You get a gold star
 By looking at the spectra of a star, we can tell what
color it is, what it’s made of, and how hot it is
 We compare this information to known stars to determine
how old it is

 We then compare it to how large the star is
(determined by other methods)

 With the age and size of the star, we can determine
how much light the star is emitting

 Using the Inverse Square Law, we can then tell how far
away it is
“A.U., …over there!”
• Space is so large that new units were made

• The Earth has an average distance of 93,000,000
miles from the Sun (150,000,000 km)
– This distance is used to determine the new unit –
____________________________ (A.U.)
– Ex. Jupiter is about 5 AU from the sun

• Astronomical units are only good for star systems
NAME         AVERAGE         AVERAGE
DISTANCE FROM   DISTANCE FROM
SUN            EARTH
Mercury       .39 AU          .61 AU
Venus        .72 AU          .28 AU
Mars        1.52 AU          .52 AU
Jupiter       5.2 AU          4.2AU
Saturn        9.5 AU          8.5 AU
Uranus      19.2 AU         18.2 AU
Neptune      30.1 AU         29.1 AU
“E.T. phone home”
• Because of the distances involved, all spacecraft
and settlements will experience a time delay when
communicating with Earth

• Sending information or having conversations would
take far longer

• This forces both humans and robots to be more
independent
NAME      TIME DELAY       MIN. TIME FOR
RESPONSE
MERCURY    5.1 minutes       10.2 minutes
VENUS      2.3 minutes       4.6 minutes
Moon       1 second          2 seconds
MARS       4.3 minutes       8.6 minutes
JUPITER    35 minutes        1 hr 10 minutes
SATURN     1 hr 11 minutes   2 hrs 22 minutes
URANUS     2.5 hours         5 hours
NEPTUNE    4 hours           8 hours
In a galaxy far, far away
• Stars produce light throughout the universe

• Light is the ________________ thing in the universe
– It travels 300,000 km (186,000 miles) PER SECOND

• So, the distance light travels in one Earth year is one
light-year
– Equal to 9.46 x 1012 km (5.87 x 1012 miles)
– Equal to ___________________ AU
Practice
 Explain how the distance to nearby objects are
determined
 Explain how the distance to objects far away are
determined
 What is a parsec?
 What can the spectra of a star tell us?
 How much light gets to Jupiter compared to Earth?
 An object is approximately 100 AU from the Sun. About
how many miles is that?

 All practice questions are due at the end of the chapter
Practice
 The closest star to Earth is Proxima Centauri, 4.2 light
years away. How many AU is that? How many miles (in
scientific notation)?
 A conversation between Mars and Earth:
   Mars: “Can’t wait to see you”
   Earth: “See you soon”
   Mars: “Bye”
   Earth” “Bye”
How long will it take from the beginning of the conversation
until the last message is heard on Mars?

 All practice questions are due at the end of the
chapter
SECTION 6
Propulsion
“Got a long way to go and a short time
to get there”
• Due to the distances involved, space travel outside
of Earth orbit takes an long time

• Time involved depends on speed of rocket as well
as path you will take to get where you are going
• A straight flight to Mars at its closest point to Earth with
a rocket travelling 40,000 km/h would take 60 days to
reach
• NOTE – This is based on the planets not moving
Spacecraft Propulsion
•   Chemical rockets
•   Ion engines/Solar-electric engines
•   Solar sails
•   Nuclear powered engines
•   Antimatter engines
Current and Near-term engines
• Chemical rockets
– What is mostly used today (called
“_________________rockets”
– Use fuel quickly and most of spacecraft is propellant
• Ion/solar-electric
– Sends a stream of accelerated charged particles
– Provides a very _________ acceleration that will
continuously build speed
– EX. An acceleration of .01m/s2 will only be at 36km/h in
the first hour, 864 km/h at the end of a day, 6048 km/h
at the end of a week, 24192 km/h at the end of a month,
and 315000 km/h at the end of a year (8 times current
chemical rockets)
“I’m sailing away”
• Solar sail - large sail attached to a spaceship that
catches the “solar wind” and light for propulsion
– Solar wind – charged particles (ie electrons, protons, etc)
ejected from the Sun
• Must be very large to have enough force applied
• Must be very thin and durable to limit weight and
vulnerability to space conditions

• Advantage – propellant is __________
• Disadvantage – acceleration is low and becomes
less the farther away from the Sun
SHIP
Future Propulsion
• Nuclear engines
– Use nuclear reactions or explosions to create thrust
– Current issues with international treaty
– Radiation factors a concern for crew and electronics
• Antimatter
– Create more energy per mass than any other type (about
100 times more than nuclear)
– Only small amounts of antimatter have been created at
high monetary and energy costs (\$62.5 ___________per
gram)
– May be able to capture naturally occurring antimatter in
Van Allen Belt or around Jupiter
“Time keeps on slipping….into the future”
• According to the Theory of ____________Relativity,
time also depends on your frame of reference
• The faster you go, the more time slows down for
you compared to the outside
• Additionally, the more gravity there is, the more
time slows down for you
• Satellites orbiting the Earth must have their clocks
updated to adjust for this effect
• Time adjustments are currently small but will
increase with velocities
“What time is it?”
• The difference in time is known as time dilation
• The formula for time dilation is:

•   v - the speed
•   c - the speed of light
•   t’ - time experienced on the outside
•   t - time experienced by the traveler
“Tik Tok”
• As people expand into space, a new timekeeping
system might need to be created
• Example: two ships leave the Earth on January 1,
2020. One travels the .5C ( ½ speed of light) and
the other travels .75C ( ¾ speed of light). They
travel to a star 4 light years away.
– When they arrive, the calendars would show:
• 1st ship:
– Calendar on Earth – January 1, 2028
– Calendar on the ship – December 2, 2026
• 2nd ship:
– Calendar on Earth – May 2, 2025
– Calendar on the ship – July 9, 2023
• The faster you go, the more and more difficult it is
to ___________________
• An effect of Special Relativity is that explains that
______________ is related to speed
• A formula similar to time dilation is used. Instead of
time, mass is substituted
• For the near future, this effect is minimal (like time
dilation)
– EX. the New Horizons space probe has a mass increase
of 3 x10 -7 percent
Practice
 A spacecraft is travelling at 50,000 km/h. Assuming
neither planet moved, how long would it take to travel
from Earth to Neptune?

 Describe each type of current and future propulsion
discussed.

 A spacecraft is able to travel at .99C (99% speed of light).
If it leaves Earth orbit on January 1st, 2012 and travels to
Proxima Centauri, what will the calendars on Earth and
the spacecraft say when the destination is reached?

 All practice questions are due at the end of the chapter
SECTION 7
Supply Requirements
Packing for the trip

• Everything an astronaut needs to survive must be
taken or recycled on the trip
• Water
• Food
• Air
• Energy
“That’s high quality H2O”
• Current NASA data indicates that at a minimum, the
average astronaut needs about _______ kg of water
per day
• A 6-month journey to Mars would require nearly
2000 kg of water (about 4500 pounds)… each way
per astronaut
• As the cost and storage for this amount is
prohibitive, astronauts must conserve water as well
as recycle it
CO2 cartridge
• When a person exhales, that person breathes out
carbon dioxide

• If not controlled, the percentage of carbon dioxide
to oxygen will increase until the air is poisonous

• ________________ must be used, maintained, and
replaced to keep astronauts alive
“Sit on it and rotate”
 One possible strategy to reduce effects of zero gravity
on astronauts is to have a part of the spacecraft spin

 Since changing direction in a spin makes an
acceleration, then a slow spin can induce partial
gravity

 The mechanism would be complex, heavy, and
expensive

 Spinning sections would have gravity but the rest of
the ship would not
ROTATING
SECTION
“Green acres is the place to be”
• Food is another concern due to weight and storage
• One possibility is to grow food
• However, soil cannot be used due to free-floating
dirt and dust

• Further requirements:
– Plants need light for ______________________
– Plants need __________________
– Plants may be able to act as air filters
– Plants need water also, which places further strain on
water supplies and also could increase humidity
Veggie tales?
• Plants selected should:
– Be easy to ____________________
– Have short life cycles
– Have seeds that are easy to collect
– Be ______________________
– Have a high food value and a wide range of amino acids

• Animals could also be brought or grown
– Increased water and food demands
Energy

 Energy is just as important to the survival of
astronauts as food, water, and air are
 Currently, the two types of energy production are:

 Solar
 The solar panels on the space station generate .25V (volts)
per 6 cm diameter solar panel

 Nuclear
substance
 As it decays, electrons are given off….so, _______________
“..Mr. Golden Sun, please shine down on
me”
 Solar cells are also called ________________cells
 photo means light
 Voltaic deals with electricity
 Literally electricity from sunlight
• The upside of solar energy is that sunlight is free
 The downside is that a large area is required to
generate increased power
 The amount of sunlight decreases with distance
from the sun
 The atmosphere of a planet can further change
the amount of sunlight
Atom Smasher
• ________________reactors – create energy by
splitting the nuclei of atoms
– Current technology
– Produces radioactive material that must be stored

• __________________reactors – create energy by
merging nuclei of atoms
– Energy is several times greater than fission for the same
mass
– Not developed yet
Practice
• About how much water would be needed for a 6
person crew to Mars (assuming a 12 month round
trip)?
• Explain the need for and the difficulties in growing food
in space
power supply system described.

• All practice questions are due at the end of the chapter
SECTION 8

Course Corrections
Mapquest
• How do you know if you are heading in the right
direction, how fast you are going, or where you are

• On Earth, you can use a map or a digital device tied
in with GPS
• For speed, you can use a speedometer

• In space, you won’t have any of these things
How far have I gone?
• NASA currently sends out a constant signal called a
________________________

• Using the time it takes to return (minus the time for
spacecraft to process and return the signal), the
distance to the spacecraft can be determined
– Time is divided by 2 to get time one-way
– Time is multiplied by the speed of light
How Fast Am I Going?
• Using signals from Earth, the speed of a spacecraft
can be determined

• The Doppler shift of the frequency is used to
determine the velocity either towards or away from
Earth
Where am I?
• Ground stations on Earth observe the spacecraft
and determine the angle of observation

• The angles from the ground stations are used to
determine the coordinates with reference to Earth

• These coordinates and the distance is used to
determine where the spacecraft is relative to Earth
• While travelling, all celestial bodies appear as stars
until a spacecraft gets closer

• NASA uses known star fields

• Spacecraft can compare the star fields to the way
that stars look around them to determine which
“Twinkle, twinkle,…”
• Star fields are based around _______ stars as
reference points
• Many of these stars are in ________________
• However, the appearance of stars can change as
you move through space
• Besides these reference points, it is important to
know where the Earth and the Sun is
Star field used by NASA Kepler mission
Lost in Space
• If signal is lost from Earth, it becomes very difficult
to know how far you’ve travelled, where you are, or
how fast you are going

• If it also becomes difficult to determine location or
heading using star fields, then it may be impossible
to get to where you are going or to get back

• Over the years, various robotic spacecraft have
been lost due to these sorts of problems
Practice
 Explain how a spacecraft knows how far it has
travelled from Earth
 Explain how a spacecraft knows how fast it is
travelling
 Explain how observers on Earth can tell where the
spacecraft is in comparison to the Earth
 Explain how a spacecraft can tell where it is and

 All practice questions are due at the end of the
chapter
SECTION 9

Introduction to Solar System
A need to know basis
• When deciding where to go, there are 3 factors to
consider
• The amount of gravity that is there
• How it compares to Earth
• Whether life might have developed there
“He ain’t heavy, he’s my brother”
• To determine how much force gravity will enact,
you need to know the mass of both objects and
how far away they are from each other

• On a planetary body, the distance is the radius from
the center to where the other object is
Law of Universal Gravitation
• To determine weight, you must first calculate
acceleration of gravity
• The formula is:

•   m1 = one mass (in kg)
•   m2 = the other mass (in kg)
•   r = the distance between them (in meters)
•   G = 6.674×10−11 N m2 kg−2
“Have you been losing weight?”
• On Earth, the average acceleration of gravity is 9.8
m/s2

• Mars has a mass that is only__________ of Earth
Mercury       3.30  1023     2439     5.79  1010       88.0 days
Venus         4.87  1024     6052     1.082  1011     224.7 days
Earth        5.974  1024     6378     1.496  1011    365.25 days
Moon      7.35  1022     1738      3.84  108       27.3 days
Mars          6.42  1023     3394     2.279  1011     686.9 days
Phobos      9.6  1015   10 to 14   9.378  106     7 hrs 39 min
Deimos       2.0  1015    5 to 8    2.346  107    30 hrs 18 min
Jupiter      1.899  1027    71,492    7.784  1011    11.86 years
Io    8.97  1022     1820      4.22  108       1.77 days
Europa      4.8  1022     1570      6.71  108       3.55 days
Ganymede      1.48  1023     2640      1.07  109       7.15 days

Callisto   1.07  1023     2400       1.88  109      16.7 days
Saturn       5.68  1026    60,268     1.427  1012    29.42 years
Titan   1.34  1023     2570      1.222  109      16.0 days
Uranus       8.69  1025    25,559     2.871  1012    83.75 years
26                         12
Solar System Overview
• Inner Planets – rocky with limited gas atmosphere
–   Mercury
–   Venus
–   Earth
–   Mars

• Outer Planets – very small rocky cores with immense
gas atmospheres
–   Jupiter
–   Saturn
–   Uranus
–   Neptune
MERCURY
•   Length of Day: 58 Earth days
•   Length of Year: 88 Earth days
•   Average high temperature: 350° C (662° F)
•   Average low temperature: -170° C (-274° F)
•   Gravity: 38% of Earth
•   # Moons: 0
•   NO LIFE EXPECTED
VENUS
•   Length of Day: 243 Earth Days
•   Length of Year: 225 Earth Days
•   Average temperature: 480° C (900° F)
•   Gravity: 90% of Earth
•   Number of moons: 0
•   NO LIFE EXPECTED
“Birds of a feather,..”
• Venus’s atmosphere is made of nearly completely
carbon dioxide
• It is the hottest planet in the solar system due to a
runaway greenhouse effect
• Studying Venus may help understand global
warming on Earth

Not quite Hell on Earth
 Cloud cover is approximately 100%
 Clouds are made of _______________________
 They reflect nearly all sunlight making it the brightest “star”
in the night sky

 May be seismically and volcanically active

 Dense atmosphere makes pressure on surface ______
times that of Earth

 Hottest planet in the Solar system (hot enough to melt
_____________)
3D view of Maat Mons with lava
plain

Impact craters with lava
Projected Near Term Destinations of US
Space Program*

*As per US Human Spaceflight Plans Committee, 2009
MOON
• No atmosphere (so little not even to count)
• Soil is a ___________and is very abrasive
– Contains helium-3, which could be extracted for future
fusion reactors
• Has an extremely weak magnetic field
• Gravity is only _____________of Earth
• Is moving away from the Earth _______ mm per
year
• Water ice has been detected on the surface
• Moonquakes up to ________ on Richter scale have
been recorded
“Moon First”
• The previous plan for the American space program
was to establish an outpost on the moon
– Could try out technologies and building techniques
before going to Mars
– Much closer (about 1/220th distance to Mars), so much
easier to provide help in emergencies
– Much cheaper to get to and much easier to launch from
(low gravity and no atmosphere)

• Observatories on the dark side of the moon would
give far better results than here on Earth
Seeking asylum
• One of the tenants of the 1963 Outer Space Treaty is
that no country can claim any part of space or any
celestial body

• However, all spacecraft, space stations, or colonies
belong to the nation that created them
– Similar to the way embassies are treated – they are
treated as part of the country that they represent even
though they are physically in another country

• Future law may be similar to the __________________
relating to outposts of multiple countries
Location, location, location
• Under the Outer Space Treaty, space and everything
in it is considered the __________________of Man
– Meaning it is to be shared for all mankind
– One meaning is that nothing in space can be owned by
an individual, group, or business (no private property)

• Space treaties only currently are related to countries

• Nothing has been specifically written about private or
business related space activities except regulating
___________________
The International Space Station
LAGRANGE POINTS
• These points are locations that are equally affected
by two opposing bodies

• The gravitational pull is cancelled out, so these
points have true ____________________ (except
for inside a spacecraft)

• Space stations in these locations would remain
there permanently without being slowly pulled in a
particular direction
Orbiting Pit Stops?
Practice
 Determine the gravity on Europa compared to the Earth
 Compare the inner planets to the outer planets of the
solar system
 Explain the factors of Venus that make life there unlikely
 List characteristics of the moon that might be experienced
by visitors
 Explain the reasons behind the Moon First approach of
space exploration?
 What is a Lagrange point?

 All practice questions are due at the end of the chapter
MARS

•   Length of Day: 1 Earth day
•   Length of Year: 687 Earth days
•   Max temperature: 20° C (68° F)
•   Min temperature: -140° C (-220° C)
•   Gravity: 38% of Earth
•   Number of moons: 2 (small captured asteroids)
•   Life possible
Previous landing sites
Mars Characteristics
• Coordinate system similar to Earth
– Instead of the Prime Meridian, there is the
_________________Meridian

• Has seasons similar to Earth due to similar tilt of
axis

• Little to no magnetic field

• ______________________are possible
Little Green Men

• Life may have existed there
• Life may still exist there

• Most plans call for Mars to be the main destination
for manned space flight this century
MARTIAN ATMOSPHERE
• Atmosphere is 95% carbon dioxide
– Relatively no greenhouse effect due to ________air
density

• Atmospheric pressure too low to exist outside of a
pressurized environment (about 1% of Earth)
– Wind blows with ___________ the force on Earth
– Sounds are not as loud

• Clouds are made of mostly carbon dioxide crystals
– It may snow dry ice (frozen carbon dioxide) at the poles
in the winter time
“Catchin’ some rays”
 Atmosphere is much thinner than Earth making
meteorite impacts more common

distance

 Surface receives more _________rays than on Earth
due to differences in atmospheric absorption

 Weak tornados have been recorded by the Spirit Mars
rover
ATMOSPHERE

DUST STORM
MARTIAN SURFACE
 Red tint of soil is due to high iron content (iron (III)
oxide)
 Could be used to extract iron and oxygen for settlements

 Soil has a pH of _______________

 Large, frequent dust storms

 Land area the same as the dry land area on Earth
 Largest volcano in the solar system – Olympus Mons
 Largest canyon system in the solar system – Valles Marineris
Olympus Mons
• Means “Mount Olympus”

• Height 25 km
– Three times as tall as Mount Everest
– Twice as tall as Mauna Kea (if measured from the sea floor)
• Diameter: approximately 600 km
– Would cover the state of ________________

• Is so much bigger than Earth mountains because
weaker gravity doesn’t make it sink back into the
ground

• Not thought to be active
Valles Marineris
• Dimensions:
– Length: 4000 km
– Width: 200 km
– Depth: up to 7km

• Grand canyon
– Length: 446 km
– Width: 29 km
– Depth: 1.6 km
Valles Marineris

3-D false color image
SUNSET…sky is blue

VICTORIA CRATER at CAPE VERDE, MARS
(near Sinus Meridian)
“Water, water, everywhere, and not a drop
to drink”
• Liquid water cannot currently exist on Mars
• Low atmospheric pressure would cause it to boil off
as per Gay-Lussac’s Law

• Majority of frozen water is at the __________
• The amount of water in the south pole of Mars
contains enough water to cover the entire planet 11
m (36 feet) deep.
• _____________(frozen water trapped in soil) exists
to 60 latitude
Areas of detected water ice
Mars First
• An alternate plan for American spaceflight is to skip
the Moon and go straight to Mars
• More public interest in Mars
• Money going to the moon could be saved and put
to the Mars mission(s)
• Unmanned rockets and robots would be launched
first
– Supplies
– Robots could build or partially build outpost
• People would be launched second
Terraforming
• One idea is to change Mars to be more Earth-like –
known as terra forming
• Most ideas would take decades to centuries and
would be the largest engineering project in the history
of man

• Ideas include:
– Covering Mars with microbes or plants that would convert
atmosphere to have oxygen
– Using impacts or other nuclear devices to cause greenhouse
effect
– Heating Mars with space mirrors/lasers to release oxygen
from permafrost
– Spreading a dark dust over surface to increase amount of
sunlight absorbed
Practice
 What characteristics of the Martian atmosphere make
wind power unrealistic?
 Compare Olympus Mons to mountains on Earth and
explain how it became so large
 A person falls off a cliff at the top of the Valles
Marineris. How long would it take to hit the bottom
(neglect air resistance)? Compare to the time
required to reach the bottom of the Grand Canyon.

 All practice questions are due at the end of the
chapter
Practice
• If Mars formerly held life that required water, where
should astronauts look for evidence?
• Explain the reasons behind the Mars first approach
to space exploration?
• Define terraforming

• All Practice questions will be collected at the end of
the chapter
ASTEROIDS
• Rubble of destroyed protoplanets from the early
Solar system
• Many exist between the orbits of Mars and Jupiter
in the main asteroid belt
• ______________asteroids – share Jupiter’s orbit
around the Sun
• Can be solid or a group of rocks travelling together
• A large enough spaceship would attract small
asteroids towards itself due to gravity
“Cha-ching”
• Asteroids can be a range of sizes
• The largest asteroid was reclassified as a “dwarf
planet” called Ceres
• Asteroids could be used as staging areas to the outer
planets
• Asteroids could also be mined for minerals
– Asteroid 16 Psyche alone could supply _____________ of
years worth of iron and nickel (at 2004 rates)
– Estimates are that a 1 mile diameter asteroid may have up
to \$20 _________________ of metals
• Some asteroids may contain or be made up of frozen
water
VESTA
CERES
Mobile home
• One idea for space station construction is to use
Near Earth Asteroids (NEA’s)

• These would be excavated and a the space station
built from the materials
JUPITER
•   Length of Day: 10 hours
•   Length of Year: 11.86 years
•   Average cloudtop temperature: -110° C (-164° F)
•   Gravity: 2.5 times Earth
•   Number of moons: 50
•   No life expected
EUROPA
• One of the Galilean moons – large moons around
Jupiter discovered by Galileo

• Icy surface (10-30 km thick)

• Expected liquid water below surface
– Approximately 100 km deep
– _________________the liquid water as Earth
– May have organisms living in these oceans
SATURN
•   Length of Day: 10 hours
•   Length of Year: 29.4 Earth years
•   Average cloudtop temperature: -180° C (-292° F)
•   Gravity: 1.07 times Earth
•   Number of moons: 53
•   No life expected
TITAN
• Largest moon of Saturn
• Has surfaces features similar to Earth

• Instead of water, it has lakes, rivers, and oceans of
methane (it even rains methane)
– Methane based oceans could sustain some types of life
– Could be a future fuel supply (maybe the Saudia Arabia
of space?)
• A frozen moon of Saturn
• Shown to have __________________– volcanoes
that erupt steam instead of lava
• Having warmth and water may be able to support
life
• __________________ has been detected – a
compound that can be given off by living things
URANUS
•   Length of Day: 17 hours
•   Length of Year: 84 Earth years
•   Average cloudtop temperature: -216° C (-357° F)
•   Gravity: .92 times Earth
•   Number of moons: 27
•   No life expected
NEPTUNE
•   Length of Day: 16.1 hours
•   Length of Year: 164.8 Earth years
•   Average cloudtop temperature: -216° C (-357° F)
•   Gravity: 1.12 times Earth
•   Number of moons: 13
•   No life expected
TRITON
• Largest moon of Neptune

• Predicted to have large underground oceans of
water (like Europa) with cryovolcanoes like
Dwarf Planets
• Objects not meeting a requirement to become a
planet
– Must not orbit another planet
– Must be large enough to be close to spherical-shaped
– Must have cleared their orbits around the sun

• Examples:
– Pluto
– Eris
– Ceres
ERIS

CERES

PLUTO
Charon
“Plutoids”
Practice
• What are two possible uses for asteroids?
• Explain why the moons Europa, Titan, Enceladus,
and Triton have special significance in studying the
solar system?
• Define dwarf planet

• All practice questions will be collected at the end of
the chapter
Warped sense of humor

• By the Theory of Relativity, gravity warps space
– This makes the path of even _____________ curve

• Recently, astronomers have detected planets
around stars by noticing a “____________” of their
starlight caused by planets passing nearby
– At present (April 2011), astronomers have detected
__________planets in ____________star systems
“Who ate my porridge?”
• For life as we know it, a planet must be an area
around their star that is habitable
– Cannot be too cold
– Cannot be too hot

• Known as the “____________________zone”
Exoplanets?
Practice
• What effect does gravity have on light?
• How did astronomers detect planets outside of the
solar system?
• Define the Goldilocks zone

• All practice questions are due at the end of the chapter
REFERENCES
• Basics of Spaceflight, NASA,
http://www2.jpl.nasa.gov/basics/index.php
• Destiny in Space, National Air and Space Museum,
Smithsonian Institution, 1994
• The Hazards of Space Travel: A Tourist’s Guide, Neil
J. Comins, PhD Villano Books 2007
• Review of U.S. Human Spaceflight Plans Committee
Final Report: Seeking a Human Spaceflight Program
Worthy of a Great Nation, 2009
• http://solarsystem.nasa.gov
REFERENCES
• http://www.braeunig.us/space/orbmech.htm
• http://planetquest.jpl.nasa.gov/
• http://www.nasa.gov/pdf/412508main_What.Is.a.P
lanet.Lithograph.pdf
• Explorations: An Introduction to Astronomy, 6th
edition, Thomas Arny and Stephen Schneider,
McGraw Hill, 2010

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