chapter 14

Exploring space

“where is everybody?”

learning objectives:

What are?

o satellites o rockets o optical telescopes (2 kinds:

reflecting and refracting) o space probes o radio telescopes o the electromagnetic spectrum o visible light/speed of light

Some of the items you should know: Any object that revolves around another object is a _______________? [Satellite] The curved path a satellite follows is an __________________? [Orbit] There are two types of telescopes discussed in this chapter: _____________ and ____________________. [Optical and radio]

There are two types of optical telescopes: _____________________________________________________? [Reflecting (concave mirror) and refracting (convex lenses)]

The speed of light is __________________. [300,000 km/s in a vacuum] a __________________ is an engine that burns fuel without air. [Rocket] The different form[s] of radiation arranged according to their wavelengths is called _______________________________? [The electromagnetic spectrum]

The electromagnetic spectrum

We know waves carry energy. Frequency is the number of wave crests that pass a given point per unit of time. The spectrum arranges waves from the shortest to the longest wavelengths.

Picture courtesy: http://www.safetycenter.navy.mil/acquisition/RFR/images/spectrum.jpg

Comprehension questions: The _____________ the wavelength, the higher the frequency. All electromagnetic waves travel at the speed of ______________; or 300,00 km/s.

The Hubble telescope

picture courtesy of http://hubblesite.org/gallery/spacecraft/06/

o The Hubble is a reflecting telescope. o Hubble Launched in 1990. o The shuttle Endeavor was sent to repair

mirror issues in 1993. o Hubble has shown galaxies in all stages of

evolution, including “toddler” galaxies that were around when the universe was still young. This helps scientists understand how galaxies form.

o Every 97 minutes, Hubble completes a spin around Earth, moving at the speed of about five miles per second (8 km per second)- — fast enough to travel across the United States in about 10 minutes.

information directly from: http://hubblesite.org/the_telescope/hubble_essentials/

optical telescopes

picture courtesy: http://www.newscientist.com/data/images/ns/cms/dn12266/dn12266-

1_600.jpg

Ooooh, say can you see???

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Refracting Telescopes: Refracting telescopes, or refractors, use a glass lens to bend, or refract, light and bring it to a focus. The lens is convex becoming thinner toward its edges. A convex lens

bends light at the edge of the lens to a greater angle than light coming through the center, so all of the rays

converge to a focus. The distance between the lens and the place where the rays converge is called the focal length of the lens. Such telescopes are usually affected by chromatic aberration, which causes the image of an object, such as a star of planet, to be surrounded by circles of different

colors, because every color has its own degree of refraction.

(http://library.thinkquest.org/TQ0313008/Optical%20Telescopes.htm)

reflecting telescopes

Reflecting telescope uses a precisely curved mirror instead of a lens to collect light. The mirror is concave, thicker

towards the edges. The mirror, which is usually parabolic in shape, focuses the incoming light instead of a glass lens. This increases the telescope’s light sensitivity, so dimmer objects

can be seen.

(http://library.thinkquest.org/TQ0313008/Optical%20Telescopes.htm)

Comprehension question:

You should be able to compare/contrast the two types of optical telescopes☺

Radio telescopes

Image courtesy:

http://www.solarnavigator.net/history/explorers_history/Radio_Telescope_Jodrell_Bank_Observatory_Lovell.jpg

♪ ♪ ♫ radio, radio ♪ ♪ ♫

radio telescopes

Radio telescopes can produce images of objects in space that would have been missed by an optical telescope. Optical telescopes need to have some kind of light to see an object, but radio telescopes don’t need light to "see." Radio telescopes helped discover pulsars (collapsed stars that send out regular pulses of radio waves) and quasars (extremely distant star-like objects that produce an enormous amount of radiation).

Many radio telescopes use a bowl-shaped reflector called a dish to collect radio waves from space. The reflector focuses the waves onto an antenna that changes them into electric signals. A radio receiver amplifies these signals and records their strength at different frequencies and from different directions. The information is analyzed by a computer to draw a picture of the

source of the radio waves or to analyze the chemicals found in the source.

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unce back to Earth. Astronomers call this technique "radar mapping."

image and information courtesy of:

(http://library.thinkquest.org/J0112188/radio_telescopes.htm)

l _________hours a day.

Large radio telescopes are also used as giant radar systems to map the surfaces of the Moon and planets. Scientists send radio waves into spto bounce them off of moons, planets, or other objects. Receivers record the radio echoes that bo

Comprehension question: Because radio waves pass freely through earth’s atmosphere, radio telescopes are usually usefu_

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Any object that revolves around another object is a satellite. A satellite can be natural, like the moon, or human (or extraterrestrial?) -

made.

image courtesy of

http://portal.unesco.org/ci/en/files/11543/10560048172esa_satellite.jpg/esa_satellite.jpg

Not so long ago, satellites were exotic, top-secret devices. They were used primarily in a military capacity, for activities such as navigation and espionage. Now they are an essential part of our daily lives. We see and recognize their use in weather reports, television transmission by DIRECTV and the DISH Network, and everyday telephone calls. In many other instances, satellites play a background role that escapes our notice. (http://www.howstuffworks.com/satellite.htm)

The first artificial satellite was sputnik 1.

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The curved path an object follows is called an orbit.

Courtesy: http://www.qrg.northwestern.edu/projects/vss/docs/space-environment/1-

what-is-an-orbit.html

An orbit is a regular, repeating path that an object in space takes around another one. An

object in an orbit is called a satellite. A satellite can be natural, like the moon, or human (or extraterrestrial?) -

made.

In our solar system, the Earth orbits the Sun, as do the other eight planets. They all travel on or near the orbital

plane, an imaginary disk-shaped surface in space. All of the orbits are circular or elliptical in their shape. In addition to the planets' orbits, many planets have moons

which are in orbit around them.

Comprehension question: CCoommpprreehheennssiioon qn quueessttiioonn:: What causes an orbit to happen?WWhhaat ct caauussees as an on orrbbiit tt to ho haappppeenn??

What causes an orbit to happen?

Orbits are the result of a perfect balance between the forward motion of a body in space, such as a planet or moon, and the pull of gravity on it from another body in space, such as a large planet or star. An object with a lot of mass goes forward and wants to keep going forward; however, the gravity of another body in space pulls it in. There is a continuous tug-of-war between the one object wanting to go forward and away and the other wanting to pull it in.

These forces of inertia and gravity have to be perfectly balanced for an orbit to happen. If the forward movement (inertia) of one object is too strong, the object will speed past the other one and not enter orbit. If inertia or momentum is much weaker than the pull of gravity, the object will be pulled into the other one completely and crash.

information directly from: http://www.qrg.northwestern.edu/projects/vss/docs/space-environment/1-what-causes-an-orbit.html

space missions

image courtesy of http://www-pao.ksc.nasa.gov/history/mercury/mercury.htm

one small step for man… one giant leap for mankind!

Step one: project mercury

o nasa created a national manned space-flight

project, later named Project Mercury, on October 7, 1958.

The objectives of the Mercury Project, as stated at the time of project go-ahead, were as follows:

o Place a manned spacecraft in orbital flight around the earth.

o Investigate man's performance capabilities and his ability to function in the environment of space.

o Recover the man and the spacecraft safely.

Mercury performed six manned flights from 1961 to 1963. Information courtesy of: http://www-pao.ksc.nasa.gov/history/mercury/mercury-goals.htm

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ooo The National Aeronautics and Space Administration

announced December 7, 1961, a plan to extend the existing manned space flight program by development of a two-man spacecraft. The program was officially designated GGGeeemmmiiinnniii on January 3, 1962

The Gemini Program was conceived after it became evident to NASA officials that an intermediate step was required between Project Mercury and the Apollo Program. The major objectives assigned to Gemini were:

• To subject two men and supporting equipment to long duration flights -- a requirement for projected later trips

to the moon or deeper space. • To effect rendezvous and docking with other orbiting vehicles, and to maneuver the docked vehicles in space, using

the propulsion system of the target vehicle for such maneuvers.

• To perfect methods of reentry and landing the spacecraft at a pre-selected land-landing point.

• To gain additional information concerning the effects of weightlessness on crew members and to record the

physiological reactions of crew members during long duration flights.

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Project Apollo's goals went beyond landing Americans on the Moon and returning them safely to Earth:

• To establish the technology to meet other national interests in space.

• To achieve preeminence in space for the United States. • To carry out a program of scientific exploration of the Moon. • To develop man's capability to work in the lunar environment.

Project Apollo had 11 manned flights in this program, with Apollo 11 being the first touch down on the moon. The last manned Apollo mission was Apollo 17.

Famous painting by astronaut Alan bean. This was his depiction of the

televised display of Galileo’s theory that in the absence of air resistance all objects fall with the same velocity. (Note the hammer and the feather).

All information courtesy/directly from: http://www.hq.nasa.gov/office/pao/History/SP-4214/cover.html

Comprehension question:

Name the three step project missions in order and describe one purpose of each mission.

rockets and shuttles

aaa rrroooccckkkeeettt is an engine that burns fuel without requiring air.

The basic principle driving a rocket engine is the famous Newtonian principle that "to every action there is an equal and opposite reaction." A rocket engine is throwing mass in one direction and benefiting from the reaction that occurs in the other direction as a result (http://www.howstuffworks.com/rocket.htm).

AAA ssspppaaaccceee ssshhhuuuttttttllleee is a reusable spacecraft that transports astronauts, satellites, and other materials to and from space.

Today the space shuttle is used mainly to service the international space station.