Rockets

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Rockets
Need to overcome Earth's gravity Therefore need
to obtain escape velocity Accelerate by throwing
out mass (fuel) at very rapid speeds Newton's
second law Velocity can be increased by losing
mass Therefore, multi-staged Heavier payloads
need bigger rockets Saturn V used send people
to the moon was the largest ever rocket as it had
the heaviest cargo
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Spacecraft
Rocket payloads are generally either
Satellites - spacecraft that orbit the
Earth Space Probes - spacecraft that leave Earth
orbit to explore the solar system All
spacecraft are designed with a Communication
antennae Power source either nuclear
batteries, or solar panels with chemical
batteries Protective outer layers Instrumentatio
n Maybe a propulsion mechanism (generally
ejected from Earth orbiting satellites)
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Satellites
Typically satellites are used for Communications
/ GPS equally spacing three geostationary
satellites will allow at least one satellite to
be visible in a straight line from anywhere on
the globe, and each of the three satellites will
have a clear straight line path of
communication. Astronomical instrumentation
e.g. Hubble Space Telescope, Chandra X-ray
Observatory, Spitzer Space Telescope Earth
Observation spy satellites, climatology
satellites
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Launching Satellites
Launch site on the Earth is carefully chosen
depending upon required final orbit. Launching at
the equator provides an Earth assist. However
polar orbiters need to be launcher at higher
latitudes.
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Observing Satellites
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HST
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Problems of Manned Spaceflight
Energy, fuel costs Radiation Provisions Muscle
fatigue Hardware, Time/Training
Costs Communications, and Remoteness in hostile
environment Psychological impact of long
duration missions
Interstellar Travel All of the above but to a
greater extent Velocities/Time