Upload
amie-day
View
219
Download
2
Tags:
Embed Size (px)
Citation preview
Unmanned Space Programs
What is the difference?
Artificial Earth Satellite A space vehicle built to
orbit the earth and perform a specific function
Space Probe Leaves the vicinity of
Earth to study planets, the sun, or another aspect of the heavens
Determining the Orbit of a Satellite
Three kinds of orbits around earth:1. Low Earth orbit (weather & cell phones)2. Polar orbit (same light for comparison)3.Geosynchronous orbit (same viewpoint)
Two factors : 1. Gravity pulling it downward 2. Its sideways speed
Artificial Earth Satellites
Two types: Scientific satellites Applications satellites
Applications satellites: Communications
Weather
Earth survey/resources
Navigation (GPS)
Surveillance (“spy”) satellites
Missile launch warning satellites
Temporary satellites (such as the unmanned replenishment vehicles for the International Space Station)
How accurately can the GPS determine a location on earths surface?
WITHIN 3-5 METERS
A satellite in a low Earth orbit is moving ________ than a satellite in a geosynchronous* orbit.
FASTER
*the orbital period of the satellite is exactly the same as the earth’s rotational period – 24 hours, and it is about 22,250 miles above the earth
Specialized Probes
Why they are “special”: They visit comets or asteroids
They are placed in special orbits to observe the sun or some other aspect of the heavens
A ________________is placed between two massive objects at a location where their gravities exactly balance each other. It orbits around this point in space.
HALO ORBIT
Space Missions
Ways that probes may carry out their missions: Fly by
Orbit
Crash into
Land on
Detach a lander
Leave the solar system completely (headed toward stars)
Why missions to Mercury and Pluto are difficult: Mercury – close to sun, high temperatures, strong radiation
Pluto – distant from earth, probe would require a large boost or special propulsion system
Planets, moons, asteroids, comets, etc.
Mercury
Ten years ago, on August 3, 2004, NASA’s MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) spacecraft blasted off from Cape Canaveral, Florida, for a risky mission that would take the small satellite dangerously close to Mercury’s surface, paving the way for an ambitious study of the planet closest to the Sun.
The spacecraft traveled 4.9 billion miles (7.9 billion kilometers) — a journey that included 15 trips around the Sun and flybys of Earth once, Venus twice, and Mercury three times — before it was inserted into orbit around its target planet in 2011.
Pluto: New Horizons
Operators at the Johns Hopkins University Applied Physics Laboratory are preparing to “wake” the spacecraft from electronic hibernation on Dec. 6, when the probe will be more than 2.9 billion miles from Earth.
Distant observations of the Pluto system begin Jan. 15 and will continue until late July 2015; closest approach to Pluto is July 14.