CHAPTER 22: EXPLORING SPACE

SECTION 1 – RADIATION FROM SPACE

What is the electromagnetic spectrum?

What is the difference between refracting and reflecting telescopes?

What is the different between optical and radio telescopes?

ELECTROMAGNETIC WAVES• Light from the Past

• When we see a star, the light left that start many years ago. Sometimes it takes millions of years for that light to reach our eyes on Earth

• This is a form of radiation (studied in heat transfer), which transmits energy from one place to another by electromagnetic waves.

• Electromagnetic Radiation

• Electromagnetic radiation is everywhere around you – turning on the radio, peering into a microscope or having an X-Ray

• Examples:

• Sound Waves (but they can’t travel through space so they are converted to Radio Waves)

• Ultraviolet Waves

• Gamma Rays

ELECTROMAGNETIC WAVES

• All of these forms of electromagnetic radiation come together to form the electromagnetic spectrum.

• Different forms have different frequencies, or the number of wave crests that pass a given point per unit of time.

• The shorter the wavelength, the higher the frequency.

• All waves travel at the speed of light, or at 300,000 km/s.

• Still, it can take millions of years for these waves to reach Earth.

ELECTROMAGNETIC SPECTRUM

OPTICAL TELESCOPES• Optical telescopes use light (a form of electromagnet radiation) to produce magnified

images of objects

• How else would we know there are craters on the moon?

• What could you use a telescope to see?

• Light is collected by a lens or mirror, then forms an image at the focal point of the telescope, then by looking through the eyepiece, it magnifies the image so you can see if clearly.

• There are two types:

• Refracting telescopes

• Reflecting telescopes

• Uses convex lenses, which are curved like the outer surface of a ball

• Light from the object passes through a convex lens and is bent to form an image at the focal point

OPTICAL TELESCOPES

Refracting Telescopes

• Uses a curved mirror to direct light

• Light strikes a concave mirror (bent inward instead of outward) and then the light is reflected into the eyepiece

OPTICAL TELESCOPES

Reflecting Telescopes

OPTICAL TELESCOPES• You can use an optical telescope (you can buy one at many outdoor stores) but

professional telescopes are located in observatories, or a dome shaped building used by astronomers and houses telescopes.

• Not all telescopes are inside a building or even on Earth – the Hubble Space Telescope was launched in 1990 by the space shuttle Discovery.

• When it was first launched, astronomers expected to see even more clear pictures, since the telescope was launched into space, but a mistake was made when the largest mirror of this refracting telescope was built.

• In December 1993, a team of astronauts set out on a mission to install new, correct mirrors on the Hubble

• NASA controls the Hubble with radio commands and images are sent back to ground with radio signals.

MAUNA KEA OBSERVATORY, HAWAII

HUBBLE SPACE TELESCOPE

HUBBLE SPACE TELESCOPE

NEW ADVANCES • Since first developed in the 1600s by Gailieo Galilei, telescopes have constantly

been improved to better serve research needs.

• Mirrors are being made larger and larger to reflect more light

• Active Optics – a computer corrects for changes in temperature, mirror distortions and bad viewing conditions

• Adaptive Optics – uses a laser to probe the atmosphere to take into account all of the possible conditions

• Currently, the plans for the world’s largest optical telescope will be housed in an observatory on the Mauna Kea dormant volcano in Hawaii. Construction has yet to begin but is estimated to be operational in 2018.

• The world’s smallest telescope is an experimental telescope to help restore vision (currently still in testing and not FDA approved)

OPTICAL TELESCOPES

Biggest Telescope Smallest Telescope

• Unlike the optical telescopes, which require light to be able to view objects in space, radio telescopes use a different method.

• A radio telescope collects and records radio waves traveling through space.

• It can be used during the day, night and most weather conditions

RADIO TELESCOPES

REVIEW – SECTION 1• How long does it take light to travel through space?

• What does the electromagnet spectrum consist of?

• What is an advantage of a radio telescope over an optical telescope? A disadvantage?

• How could adaptive optics help optical telescopes?

• Page 635 – Define the following terms:

• Rocket

• Satellite

• Orbit

• Space probe

SECTION 2

What are natural and artificial satellites?

What are the differences between artificial satellites and space probes?

What is the history behind the race to the moon?

ROCKETS

• Special engines that carry their own fuel and work in space, or rockets, are responsible for the blast off into space

• To break free of gravity, spacecraft must travel at a speed greater than 11 km/s (same as 24,606.2992 mph!!!!)

• Why do rockets need their own fuel?

• Rockets do not require air to burn their fuel – space has no air for it to use!

• An example of a simple rocket would have a burning chamber and a nozzle

• There are two types of rockets that are categorized by the type of fuel they use

• Solid, rubberlike fuel

• More simple

• Cannot be shut down after they are ignited

• Can be used in combination with liquid fueled rockets for launching

• Liquid fuel

• Can but shut down and restarted after ignited

• Preferred for long-term space missions

• Scientists on Earth can send start and stop signals to the spacecraft’s engines whenever they need to

ROCKETS

Liquid Propellant Solid Propellant

ROCKETS

• Sputnik I was launched in 1957 by Russia and was the first artificial satellite

• Any object that revolves around another object

• In space, there is no gravity, but the gravitational pull from Earth is what holds satellites in place in their orbit, a curved path around Earth.

• Sputnik I orbited for 57 days before being pulled back into Earth’s orbit and burning up.

SATELLITES

WHY USE SATELLITES?

• Artificial satellites are used to communicate data back to Earth

• Communication Satellites allow use to watch TV and talk on our phones

• Weather Satellites monitor current conditions all over the globe

• Scientific satellites help gather information for NASA and other scientific organizations

• Navigational satellites help planes and ship know where to go

• Military satellites give top secret information

• An instrument that gathers information and send it back to Earth

• Unlike satellites, which only stay in Earth’s orbit – probes travel into the solar system

• Example: Pioneer 10

• Launched in 1972

• Sent back photos of Jupiter as the first probe to encounter an outer planet

• Transmitter failed in 2003 but it continues on through space

SPACE PROBES

• Voyager I and Voyager II were launched in 1977 and are now headed toward deep space

• Voyager I flew past Jupiter and Saturn

• Voyager II flew past Jupiter, Saturn, Uranus and Neptune

• These probes continue to explore the solar system and transmit data and are expected to do so for at least 20 more years

SPACE PROBES

VOYAGER I AND VOYAGER II

• Launched in 1989

• Reached Jupiter in 1995

• Released a smaller probe to travel to the surface of Jupiter

• Before it was crushed in the atmosphere, it transmitted information about Jupiter’s

• temperature

• Composition

• atmospheric pressures

• rings, moons, and magnetic fields

GALILEO

• Jupiter’s moon Europa shows the possibility of an ocean under the icy surface

• The study of Europa ended in 2000 – more advanced probes are needed to study Europa

• October/November 1999, the probe approached Io, which contains a volcanic vent named Loki, which emits more energy than all of Earth’s volcanoes COMBINED

GALILEO

RACE TO THE MOONThree stages led the United States to reach a goal for all man kind

PHASE I: PROJECT MERCURY

• Russia launched Sputnik I in 1957

• 1961 – Russia sends Yuri A. Gagarin into space and returned home safely. After this, President Kennedy called for the US to someone to the moon and return them safely to Earth and make it happen by 1960

• This launched Project Mercury – whose goal was to orbit a piloted spacecraft around Earth and bring it back safely

• May 5, 1961 – Alan B. Shepard became the first US citizen in space

• 1962 – Mercury astronaut John Glenn became the first US citizen to orbit Earth

PHASE II: PROJECT GEMINI

• Goals:• Have two spacecraft meet in space and connect

• The Gemini spacecraft was launched by a liquid fueled rocket known as Titan II

• Study the effects on space on the human body

• Send space probes to the Moon

• Ranger was the first sent to the Moon

• Surveyor landed on the Moon in 1699

• Lunar Orbiter took photos of the Moon’s surface to determine the best landing spot

PHASE III: PROJECT APOLLO

• Goal: reach the Moon’s surface

• July 20, 1969 – Apollo 11 lands on the Moon’s surface

• Neil Armstrong was the first human to set foot on the Moon

• “That’s one small step for man, one giant leap for mankind”

• Three astronauts explored its surface for two hours while others remained inside the Command Module

• Total of six lunar landings brought back more than 2000 samples of moon rock and soil