Space Flashcards
Planet
An object that does not undergo nuclear fusion but orbits a star/sun.
Dwarf planet
An object that orbits a star and is similar to a planet but is not large enough to clear its orbital path of debris.
Moon
A natural satellite that orbits a planet
Star
A large ball of hot gases that is undergoing nuclear fusion and emitting electromagnetic radiation.
Sun
A star at the centre of a solar system
Asteroid
An object that orbits the sun that does not fulfil planetary criteria
Solar system
A central star orbited by planets
Exoplanet
A planet outside our solar system that orbits a star
Galaxy
A cluster of gravitationally bound stars, gas and dust clouds.
Universe
Consists of many galaxies separated by empty space.
how do satellites orbit planets?
Satellites orbit the Earth when their speed is balanced by the gravitational pull on Earth. Their horizontal speed can therefore beat the downward pull of gravity, allowing it to continuously “fall” towards the Earth while circling it. This is how the moon naturally orbits the Earth.
period + altitude of a geostationary satellite
The period of a geostationary satellite is 24 hours.
The altitude of a geostationary satellite is 36,000km.
what effect does altitude have on a geostationary satellite?
The higher the altitude of a satellite, the longer the period of the satellite, as it will have a further distance to travel within one orbit of the Earth.
Challenges of space travel 1
Sufficient energy is required to power life support system for space travel.
Solution:
Energy can be generated on a spacecraft using solar cells.
Challenges of space travel 2
Travelling long distances in space is very difficult and requires a very fast speed, while maintaining energy and fuel.
Solutions
Energy can be preserved and high velocities can be reached by ‘catapulting’ a space craft utilising the gravity of a large object, such as a moon or asteroid.
Large distances can be travelled using ion drive, where a small unbalanced force over an extended period of time allows a high velocity to be attained.
Risks of space exploration
Exposure to radiation.
Re-entry into the atmosphere is very dangerous.
Fuel load on take-off has a risk of ignition and explosion.
Pressure differential between the vacuum of space and the atmospheric pressure maintained in the spacecraft poses a risk to astronauts.
How Newton’s third law works w a rocket
When a rocket burns fuel, thrust is generated, propelling the rocket upwards. An equal and opposite push is created by the exhaust gas downwards, allowing the rocket to overcome the force of gravity and to be propelled upward.
How old is the universe?
13.8 billion years
What is the big bang theory
The Big Bang Theory states that all current and past matter in the Universe came into existence at the same time from a small point of energy that exploded with extreme force.
what is a light year
A light year is the distance that light travels in a year.
(365.25 X 24 X 60 X 60)
Three types of line spectra
Continuous spectrum, Absorption line spectrum and Emission line spectrum
Benefits of space exploration
Weather forecasting
Environmental monitoring
Detail of the oceans
Climate monitoring
The Hubble space telescope
The HST placed a visible light telescope in orbit, to avoid the blurring effect of the Earth’s atmosphere
Ion drive
Ion drives are a form of rocket which use Newtons’s third law to propel spacecrafts. Instead of sending out hot gases like a chemical rocket an ion drive sends out ionised gas particles.
They create a small unbalanced force over an extended period of time.
Ion drives produce low levels of thrust but are very efficient, and if fired for long periods of time can make a significant difference to a craft’s velocity.
Maintaining sufficient energy to operate life support systems
We need food, water, air (oxygen), heat and light. Space does not have these things. Electrical energy is used to operate the equipment of the spacecraft to meet these requirements.
The main electrical power source used on spacecraft in photovoltaic solar cells (they convert the sun’s light energy into electricity). Problem is, they were heavy and inefficient. Space exploration I has made developments into making them thinner, more efficient and cheaper.
Problem with this, what are you going to do when the spacecraft is not able to be near the sun?
Travelling large distances using a ‘catapult’
Spacecraft catapult or slingshot around a planet by entering and leaving the gravitational field of a planet. The spacecraft’s speed increases as it approaches the planet but decreases while escaping its gravitational pull. However, as the planet is orbiting the Sun, and the spacecraft is affected by this motion during the manoeuvre. To increase speed, the spacecraft flies with the movement of the planet, taking a small amount of the planet’s orbital energy. The slingshot manoeuvre can change the spaceship’s trajectory and speed relative to the Sun.
Manoeuvring a spacecraft in a zero friction environment
In the vacuum and micro-gravity of Earth orbits means there is a near friction free environment. Ion drives and rocket engines must allow craft to accelerate, but to stop or slow that motion the spacecraft must produce the opposing force itself. This is done using secondary manoeuvring thrusters, either to provide the opposing thrust directly or to turn the craft so it can fire its main engines in the desired direction.
When Soyuz craft are docking with the ISS, they must match their speed with that of Space Station and get the docking hatches to meet up to within ten centimetres. That level of precision requires the flight commander to be able to make fine adjustments to the speed, angle, and height of the approach.
Fuel load on take-off
Rocket engines use Newton’s 3rd Law to propel spacecraft. The engine burns fuel to produce hot gases which are ejected from the engine, the hot gases push back on the spacecraft body sending it forward.
At take off these rockets contain incredible amounts of highly combustible fuel. An Ariane rocket contains around 400 000kg of fuel at take off to get objects into a low Earth orbit, considerably more for a geostationary satellite.
Potential exposure to radiation
The Earth’s atmosphere provides us with much more than the air we breathe. It does a fantastic job of protecting us from harmful radiations from the sun and other stars.
While in space, astronauts are exposed to radiation mostly composed of high-energy protons, alpha particles, and high-atomic-number ions. They are also exposed to radiation from nuclear reactions in some spacecraft. Galactic cosmic rays from outside the Milky Way galaxy consist mostly of highly energetic protons.
Astronauts are exposed to between 50-2,000 millisieverts (mSv) while on six-month-duration missions to the International Space Station. The risk of cancer caused by ionizing radiation is well documented at radiation doses beginning at 50 mSv and above.
Pressure differential
However, during spacewalks and when travelling in capsules to and from the station, the astronaut’s spacesuits provide that pressurised environment. It is part of the reason that spacesuits look so bulky.
Micrometeorites are tiny pieces of meteorite that travel through space. Though they are very small the speeds they travel at can mean they can cause a lot of damage, potentially puncturing a spacesuit. To prevent this, spacesuits are made from layers of Kevlar.
The multiple layers and pressurised suits reduce the mobility of astronauts. Engineers from the space programs are continually working on how to make the suits easier to move in.
Re-entry through an atmosphere
Re-entering the Earth’s atmosphere at high speed is very dangerous, and if a craft is not properly shielded against re-entry heat and/or enters at an incorrect angle, it can break up and burn up in the atmosphere
How many metres are in a light year
9.46x10^15 metres in a light year
Continuous spectrum
Complete colours blended together
Line absorption spectra
Looks like the continuous spectrum except a few lines of black are there
Line emission spectra
Completely black except for a few lines of colour (the complete opposite of line absorbtion)
How are radio waves detected
Detected using a curved reflector using antenna/aerial
How are microwaves detected
Detected using a curved reflector using antenna/aerial
