Travel to Space

Rockets

action

reaction

• Newton’s Third Law – for every action there is an equal and opposite reaction

• rocket gas is under pressure in a tank• when gas is released in a combustion

reaction it produces a downward thrust• then the rocket lifts upward and away

from Earth in an opposite reaction• rockets must reach an escape velocity

of 28000 km/h to overcome Earth’s gravitational pull

• there are 3 basic parts to a rocket– the structural and mechanical parts (engines, storage

spaces, tanks, fins)– fuel (can be various materials such as liquid oxygen,

gasoline or liquid hydrogen– payload – what is being transported by the rocket

(people, food, water, air, cargo)– what are possible payloads (what types of things are

being transported by rockets)

• Fins – are important because they stablilize the rocket (so it does not wobble) and make it more efficient

• designed in stages so empty fuel tanks can be dropped when the fuel is used up… this makes rockets more efficient

Technologies for Space Travel(theoretical propulsion systems)

• Ion drives– engines that use xenon gas instead of chemical fuel– xenon is electrically charged in the engine, accelerated, then

emitted as exhaust– exhaust creates thrust which pushes spacecraft in opposite

direction

• Solar Sails similar to wind pushing sailboats– solar sails collect electromagnetic energy from the Sun… when

‘photons’ hit the sail they transfer energy which causes the spacecraft to move forward

• Gravitational Assist – fly a spacecraft toward a planet or star, then at the last minute

pull around it and away… creating a slingshot effect that shoots the craft forward in the desired direction

Space Craft• space shuttles are used to transport

people into space• space probes are used for ‘non-

manned’ exploration of space – they carry instruments for recording info– e.g. Pioneer 11 – flyby of Jupiter and

Saturn in 1974 - 79– e.g. Mars Pathfinder – landed on Mars in

2000

• space stations are orbiting space craft that have living quarters, work areas, support systems… to allow for people to live and work in space for extended periods of time

Satellites and Probes

• natural satellites such as the moon• man-made satellites such as used

for communication– Communication satellites – “wireless”

technologies– Observation and research satellites –

weather, tracking systems (e.g. radar)– Remote sensing – imaging of earth

surface– Global Positioning Systems

Satellite Orbits• Low Earth Orbit

– 200 – 1000 km altitude– e.g. remote sensing

satellites• Geosynchronous Orbits

– medium or high Earth orbit– satellite moves at the same

rate as the Earth… so it records the same area of the Earth at all times

– e.g. weather satellites• Geostationary Orbits

– medium or high Earth orbit– satellite stays in one place

while the Earth moves… so it records a different area of the Earth over time

– e.g. communication satellites

Hazards of Space Travel

• Launch hazards – combustion of fuel and escape of Earth’s gravity are risky

• Cosmic and solar radiation – medically hazardous for human health

• Collisions – natural hazards and man made (space junk)

• Re-entry into an atmosphere – risk of burning up due to friction of Earth’s atmosphere on craft

• Fuel expenditure – running out of fuel

Living in Space

• Sustainable food and water supply– need sophisticated wastewater recycling

capabilities to produce drinking water– food provides high energy for low

volume and weight

• Environmental setting– steady temperature, pressure &

humidity– passing electricity through water to

produce oxygen

• Waste management– removing carbon dioxide from air– filtering micro-organisms and dust from

air– handling biological waste and garbage

• Safety– space is a vacuum – no air or water– detection for fire, leaks, incoming risks

like meteorites– protection from radiation and cold– systems to handle emergencies like a

fire or loss of pressure/air

Water Recycling System – International Space Station

SIA – page 422

• Movement outside habitat requires:– space suit– supply of oxygen– water supply (&

food)– temperature control– waste management

• carbon dioxide• body waste

– communications– attachment (to

space craft)

Physical and Psychological Risks

• microgravity – lower gravity– produces lower stress on our bodies– can result in loss of muscle mass,

expansion of bones, weakening of heart– visual depth perception is affected

• confined living - isolation– limited space– limited companions– no fresh air

Telescopes

• Optical telescopes → light collectors– use a series of lenses or mirrors to collect

and focus light & images from space– larger lens = more visibility– operate in the visible light spectrum– first developed in 1608 by Hans

Lippershey… but it was Galileo who is credited with using telescopes to study the night sky

• Reflecting Telescope– 2 lenses gather and

focus light– disadvantage is that

the lens will warp if diameter > 1 m

• Refracting Telescope– uses mirrors to

gather and focus the light

Radio Telescope• resemble a large satellite dish• gather radio waves • advantage over optical

telescopes, because they are not affected by weather, clouds, atmosphere or pollution

• have greatly expanded our knowledge of our solar system and galaxy

Interferometry

• combining 2 or more optical OR radio telescopes to detect objects with better clarity at greater distances

Telescopes in Space

• telescopes located in space have a better view because there is no atmosphere to distort the images

• Hubble Space Telescope– orbits 600 km above the Earth– reflecting telescope– launched in 1990

Electromagnetic Spectrum

Radio Telescopes operate within wider band of radio waves

Optical Telescopes operate within narrow band of

visible light waves

Useful Inventions from Space Exploration

SIA, page 431