Unit 2 Space Exploration.docx

Space Exploration 6\. Above the Atmosphere and Under Control  Rockets -- Getting Up There  There are three basic parts to a rocket:  1\. Machinery is everything from the rocket itself to engines, storage tanks, and the fins on the outside that help guide the rocket during its flight.  2\. The f...

Space Exploration 6\. Above the Atmosphere and Under Control  Rockets -- Getting Up There  There are three basic parts to a rocket:  1\. Machinery is everything from the rocket itself to engines, storage tanks, and the fins on the outside that help guide the rocket during its flight.  2\. The fuel can be any number of materials, including liquid oxygen, gasoline,  and liquid hydrogen. The mixture is ignited in a combustion chamber, causing  the gases to escape as exhaust out of the nozzle.  3\. The payload refers to the materials needed for the flight, including  crew cabins, food, water, air, and people.  The science of rocketry relies on a basic physics principle:  Technologies for Space Exploration  The Hubble Space Telescope has been orbiting Earth's atmosphere since 1990.  Radio and television satellites are usually placed in  geosynchronous orbit, which means they move in  the same direction as Earth rotates. They are  about 36,000 km above Earth and directly over the  equator. They take 24 h to orbit Earth once, and  appear to be motionless. Radio and television  satellites are often placed in geosynchronous orbit  so that the signal can be useful for people in one  location, e.g. a television satellite for people living  14  Space Exploration What happens to old space junk? About 95% of all objects in the  diagram to the right are orbital debris, not functional satellites. As  satellites get old, engineers will use its last bit of fuel to slow it down  so it will fall out of orbit and burn up in the atmosphere. What about  objects that are too large to burn up completely? Operators can plan  to have remaining debris fall into a remote location. This place,  nicknamed Spacecraft Cemetery, is in the South Pacific Ocean.  Farther satellites are instead sent even farther away into a graveyard  orbit in space. There is so much space junk that one tiny collision could trigger a big chain reaction, a possibility called the "Kessler Effect." To prevent a disaster like this from happening, anyone launching anything into orbit must now have a plan for the end of the device's life.  Watch how space agencies are dealing with space junk: [https://youtu.be/SLEzsr46Hbk] Five Canadian Contributions  1\. Astronauts -- Chris Hadfield (his many musical moments in space can be found on YouTube), Roberta Bondar, and more!  5\. Space farming -- The University of Guelph leads the world in research for building greenhouses in space using hydroponics, or growing plants without soil.  15  Space Exploration The Future of Space Travel  1\. Ion drives -- Xenon gas is electrically charged, accelerated, then emitted as exhaust. Thrust generated by an ion drive is 10,000 times weaker than today's chemically fueled rockets, but the force generated lasts a very long time and uses very little energy. In space, a little amount of force goes a long way.  2\. Solar sails -- The Sun emits electromagnetic energy in the form of photons, which strike and propel the carbon fiber solar sails. The momentum from the photons is transferred to the sails, propelling them up to five times faster than current space crafts. The light sails do not require a lot of force to be set in motion. See what Bill Nye has to say: [https://youtu.be/ORQNgKnKVvM]  3\. The International Space Station (ISS) -- Currently orbiting the Earth at an altitude of 350 km. It is a joint project between sixteen nations, including the USA, Canada, Japan, Russia, and Brazil, as well as eleven European nations. The space station is in low Earth orbit, and can be seen from Earth with the naked eye. It orbits at an altitude of approximately 350 km above the surface of the Earth, travelling at a speed of 7.66 km/s, completing one orbit around Earth every 92 minutes!  Assignment  3\. Name two alternatives to rocket engines that scientists are studying as a means of propelling spacecraft on long journeys.  4\. Explain what would happen if a rocket's payload were greater than the allowed percentage. 5. What is the main attraction for using an ion drive for powering spacecraft?  6\. Besides saving in fuel costs, what is the other main advantage to using a solar sail?  7\. Space probes are often sent into space to collect information for scientists to study; they do not have astronauts. Name and describe two other objects that are sent into space.  8\. How do left-over materials in space pose a threat to people on the ground?  16  Space Exploration 7\. People in Space  Space begins approximately 100 km above Earth, but Earth's gases (considered its atmosphere) may extend up to 600,000 km above Earth. Outside of the atmosphere lies the cold vacuum of space. It is an environment that is hostile to humans in many ways. NASA is close to having the technology to send humans to Mars and back, however, a mission like this would take two to three years.  Hazards of Living in Space  1\. Environmental Hazards -- Since space is a vacuum, there is no oxygen or water. Other hazards include the damaging effects of cosmic rays and solar radiation, being hit by meteoroids, extremely cold temperatures in the shadows or extremely high temperatures in the full sun (due to no atmosphere). The air pressure that helps regulate our heartbeats is also missing.  2\. Psychological Challenges to Confined Living: Astronauts maintain close, confined quarters for long periods of time, up to two years.  3\. Effects of Microgravity on the Body -- Astronauts on the ISS work in a microgravity environment. This means the gravitational forces on the body are greatly reduced. In space, astronauts are nearly weightless, which can confuse the body's senses. Many astronauts develop space sickness, which is like motion sickness. They feel nauseated and dizzy and have headaches. They may vomit, which can be very dangerous if they are wearing a spacesuit. Space sickness goes away as the astronaut adjusts to microgravity, but they may need to wear a medication patch on their skin to reduce the effects while on space walks.  and the heart does not have to pump as hard to circulate blood. Muscles do not get used as much and weaken, so astronauts exercise to keep their muscles in good condition. Even visual depth perception is affected. When astronauts return to Earth, it takes several weeks for the body to return to normal.  Storage Space and Recycling in Space  17  Space Exploration Space Suits  The first space suits were worn on the Mercury spacecraft in 1962. They were  Travel into outer space has required  the development of the current  suit, the EMU (Extravehicular  Mobility Unit). It is sturdy enough to  withstand the harsh environment of  space (such as micrometeoroids  and the harsh radiation of the Sun),  but is also more flexible. When the  astronaut wears it, they must be  able to walk, bend over, grasp a  wrench, or twist a bolt. These suits  have their own supply of oxygen, as  well as cooling and communication  systems and a portable toilet! These  space suits are custom-designed for  the person who will wear them.  Essentially, the space suit is a  mini-Earth system that allows the  wearer to work freely outside the  craft.  The Pros and Cons of Space Exploration  Many people argue that there are so many problems on Earth that require solving, for example:  18  Space Exploration 1\. Space could be a source of resources such as solar energy, and mineral resources from rocks in the asteroid belt.  2\. The cost of space travel could be cut by using material in space for the construction of space vehicles, supplies and fuel. For example, both hydrogen and oxygen can be easily processed from Moon rock, which then could be combined to form and supply water.  Political, Ethical, And Environmental Issues  Who owns the resources in space, and who has the right to use them will be up for debate if space development does continue?  Environmental questions: Who is responsible for protecting space environments from alteration? Who is responsible for cleaning up space junk, and who should pay for doing it?  Assignment  1\. What are three hazards of living in space?  2\. Briefly describe how working on the International Space Station might affect a person psychologically.  3\. What is the difference between gravity and microgravity?  4\. Explain why a regular ball-point pen will not work in space.  5\. What effect does living in space for extended periods of time have on  a\. bones?  b\. muscles?  6\. List some characteristics or features that a space suit must possess in order to be functional for a particular astronaut.  7\. Use examples to explain the value of recycling in space.  8\. How is oxygen produced in space?  9\. Why might asteroids be of interest in space exploration?  10\. List three costs of space exploration, and three benefits.  19  Space Exploration 8\. Up Close: Galaxies & Our Solar System  To people of long ago, the bright band of stars, gas, and  dust that was visible in the night sky looked like milk that  had been spilled along a pathway. As a result, that galaxy  that is home to our solar system was called the Milky  Way Galaxy. All of the stars you can see at night and  several hundred billion more are all bound together by  gravity.  The Milky Way, a spiral galaxy, is shaped like a flattened  pinwheel, with arms spiralling out from the center. From  the side, it looks like a CD with a marble in the middle  sticking out evenly on either side.  You can make a rough guess of the number of stars in our  galaxy by dividing the Galaxy's total mass by the mass of  There are millions of galaxies, each with millions of stars. Most galaxies have common features as seen in the Sombrero Galaxy, a lenticular galaxy, that is pictured:  1\. A bulge which is the round center of the galaxy. It  contains billions of stars, as well as gases and dust.  Here, the stars are quite old in comparison to the  stars in the rest of the galaxy.  2\. The disk, which surrounds the bulge, is the  flattened portion of the galaxy and contains mostly  younger stars. A disk is not present in an elliptical  galaxy.  3\. The halo is the ring of gases and stars that extends beyond the galaxy. Halos are easier to see in spiral galaxies than in other galaxies. In elliptical galaxies, it can be hard to see where the bulge ends and the halo begins. Halos contain dust, gas, dark matter, and may also contain globular clusters.  4\. Spiral arms are only present in spiral galaxies. They are curving arms that spread out from the bulge, giving the spiral galaxy its pinwheel appearance. The spiral arms contain mainly younger stars, gas, and dust.  20  Space Exploration Galaxies take these shapes:  4\. Lenticular: has a bulge, disk, and halo, but does not contain spiral arms. There is little gas, meaning little star formation occurs, and the existing stars are quite old.  Label the shape of these galaxies:  \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_  Our Solar Neighbourhood  The formation of our solar system is based on the protoplanet hypothesis or nebular theory, which follows three steps:  1\. A cloud of gas and dust in space begins swirling.  21  Space Exploration Take notes on the eight planets using the NASA website: [https://solarsystem.nasa.gov/planets/overview/]  +-------------+-------------+-------------+-------------+-------------+ | Planet &  | Date  | Diameter  | Average  | Length of  | | | | | | | | Planet  | Discovered | (km) & | \# of  | ~Day\ &\ Ye | | | | Size  | | ar~Composit | | Type | | | Surface  | ion | | | | Compared  | | | | | | | Moons  | | | | | to Earth | | | | | | | Temp | | +-------------+-------------+-------------+-------------+-------------+ | Mercury | | | | Day:  | | | | | | | | | | | | Year: | +-------------+-------------+-------------+-------------+-------------+ | Venus  | | | | Day:  | | | | | | | | | | | | Year: | +-------------+-------------+-------------+-------------+-------------+ | Earth | | | | Day:  | | | | | | | | | | | | Year: | +-------------+-------------+-------------+-------------+-------------+ | Mars  | | | | Day:  | | | | | | | | | | | | Year: | +-------------+-------------+-------------+-------------+-------------+ | Jupiter  | | | | Day:  | | | | | | | | | | | | Year: | +-------------+-------------+-------------+-------------+-------------+ | Saturn | | | | Day:  | | | | | | | | | | | | Year: | +-------------+-------------+-------------+-------------+-------------+ | Uranus  | | | | Day:  | | | | | | | | | | | | Year: | +-------------+-------------+-------------+-------------+-------------+ | Neptune | | | | Day:  | | | | | | | | | | | | Year: | +-------------+-------------+-------------+-------------+-------------+ 22  Space Exploration The Sun  The Sun is at the center of our solar system. Our Sun is one million times bigger than Earth and has a diameter 110 times wider than Earth. The surface of the Sun, which is always bubbling and boiling, is about 5500°C, while the core is close to 15 million degrees Celsius.  The Sun contains mostly hydrogen and helium, which is packed very densely at its core. The Sun emits charged particles in all directions. This solar wind bombards the Earth at 400 km/s, but the Earth's magnetic field protects us.  Asteroids  The path of a comet is elliptical, enabling astronomers to predict when the comet will pass by Earth again. Halley's comet has an average 76-year orbit, and was last observed in 1986. Shortly afterward, observers saw it brighten unexpectedly, which might mean it collided with something. We will have to see what happened when it returns again in 2062.  23  Space Exploration Meteoroids, Meteors, and Meteorites  Tracking Objects in the Solar System  You learned previously that the paths of planets have elliptical paths. This can  planets orbit the Sun in roughly the same plane. Pluto, however, has an orbit  that is raised 17.2° from the plane of the other planets. Additionally, Pluto's  The understanding of orbits has led to the discovery of many different comets. NASA tracks asteroids, comets, and meteors that have been discovered by observatories and amateur astronomers.  Assignment  1\. What is the solar wind?  2\. How does the Sun release energy?  9\. For about 20 years, from 1979 to 1999, Pluto was closer to the Sun than Neptune was. Explain why this was possible.  10\. Suppose a gaseous planet half the size of Saturn was discovered. Where in the solar system do you think it would be located? Give a reason for your answer.  11\. Most of the worlds in the solar system that have solid surfaces show evidence of heavy cratering. Suggest a reason for this.  24  Space Exploration 9\. Beyond the Milky Way  Astronomers estimate the age of the universe to be about 13.8 billion years. They calculate this age by measuring the distances and radial velocities of other galaxies, most of which are flying away from our own galaxy.  What Is A Star?  A star is a hot, glowing ball of gas  (mainly hydrogen) that gives off  tremendous light energy. There are  billions of billions of stars in the  universe. They vary in temperature,  brightness, size, and colour, as shown  by the Hertzsprung-Russell diagram to  the right. 90% of all stars fit into this  grouping. Our Sun belongs in the  middle of the main sequence  grouping.  Colour the stars. The giants are yellow and the main sequence stars are in rainbow order.  Stars vary greatly in their characteristics. Betelgeuse is 670x larger than our Sun, but only 1/10-millionth as dense. Our Sun is a very average star. If it was 1 m wide, the largest known star would be 2300 m (or 2.3 km) wide!  The Birth of a Star  Just like living organisms,  stars have a life cycle: they  are born, live, and die. The  life cycles of massive stars  differ from those of  Sun-like stars, as shown in  the diagram.  A nebula is a region of gas  and dust where stars form.  Each is composed of about  75% hydrogen and 23%  helium. The other 2% is  oxygen, nitrogen, carbon,  and silicate dust. Some of  this interstellar matter  came from exploding stars.  25  Space Exploration The attraction of gravity acting between atoms of gas and grains of dust causes a small area of the nebula to start collapsing into a smaller, rotating cloud of gas and dust. As more material is drawn into the spinning ball, the mass at its core increases and the temperature climbs. If the core gets hot enough, it will start to glow forming a protostar, the first stage in a star's formation.  The interior of the protostar gets hotter and hotter, reaching 10 million degrees Celsius, and hydrogen starts to change to helium. This process is known as fusion, and it releases great quantities of energy and radiation. The star has been born.  A star's mass determines whether it is a Sun-like or a massive star. Both spend most of their time in the main sequence with fusion occurring in their cores. The outward pressure generated by fusion is counteracted by gravity, and the star is stable in this phase. All stars remain in this state for millions to billions of years.  As the nuclear fuel of the star runs out, so does the energy required to keep the gases together and the star expands dramatically. A Sun-like star becomes a red giant and a massive star becomes a red supergiant. For us, our Sun will become a red giant in about 5 billion years, expanding to have a diameter beyond the current orbit of Mars.  as a neutron star or a black hole. A neutron star is a  rapidly spinning object that is only about 30 km in  diameter; it is too small to form a black hole. A black  hole, shown to the right, is a highly dense remnant  of a star in which gravity is so strong that even light  cannot escape! Although they are invisible to  telescopes, material close to a black hole emits a  tremendous amount of light so we can see them  indirectly.  26  Space Exploration Assignment  1\. What is the main chemical element in a star?  2\. What is the connection between a supernova and a black hole?  3\. What is the term used to refer to a group of millions of stars?  4\. Explain the Hertzsprung-Russell diagram in your own words.  5\. Why are nebulae sometimes referred to as "stellar nurseries"?  6\. Create a word sequence that correctly summarizes the life cycle of massive stars. Use the words: red supergiant, nebula, supernova, massive star, neutron star. Connect each word with an arrow:  7\. Considering the number of stars in space, why don't astronomers see greater numbers of dwarf stars?  8\. Imagine two stars in a galaxy. Both are at the end of their life spans. One star ends up as a white dwarf, the other ends up as a black hole. Describe the conditions that led to these stars having different outcomes.  9\. The light we see from the planets in our solar system is just the light reflected from the Sun. Why do planets appear brighter than the vast majority of stars we see?  27  Space Exploration