Bit of Administration ….Bit of Administration ….

• LabLab– If cloudy through Sunday, may need to continue next month.If cloudy through Sunday, may need to continue next month.– If one clear night, proceedIf one clear night, proceed

• HomeworkHomework

• 6-week Test6-week Test

• ReadingReading– Download NASA article from Download NASA article from www.astro.wisc.edu/astro104

In you were going to point in the direction that the Earth is In you were going to point in the direction that the Earth is rotating*, you would point rotating*, you would point

A) To the EastA) To the East B) To the WestB) To the West

* Or put another way, the direction that you are moving right * Or put another way, the direction that you are moving right now because of the rotation of the Earth.now because of the rotation of the Earth.

ConcepTest!ConcepTest!

Cape CanaveralCape CanaveralEarth RotationEarth Rotation

10,800 km/hr10,800 km/hr

AstronauticsAstronautics• Special OrbitsSpecial Orbits

GeosynchronousGeosynchronous36,000 km36,000 km

Mid-Earth OrbitMid-Earth Orbit20,000 km20,000 km

Low-Earth OrbitLow-Earth Orbit200 km200 km

NP

AstronauticsAstronautics• Special OrbitsSpecial Orbits

MoonMoon

AstronauticsAstronautics• Special OrbitsSpecial Orbits

Mid-Earth Polar OrbitMid-Earth Polar Orbit20,000 km20,000 km

12 hrs12 hrsSpy Satellites, GPSSpy Satellites, GPS

Cape CanaveralCape CanaveralEarth RotationEarth Rotation

10,800 km/hr10,800 km/hrVandenberg AFBVandenberg AFB

If you are going to launch a satellite into a polar orbit from If you are going to launch a satellite into a polar orbit from Vandenberg AFB, in which of these directions would you Vandenberg AFB, in which of these directions would you launch? launch?

A) SoutheastA) Southeast B) SouthB) South C) SouthwestC) Southwest D) WestD) West

ConcepTest!ConcepTest!

AstronauticsAstronautics

• Orbital ManeuveringOrbital Maneuvering

After the servo rocket burn in the picture below, in which After the servo rocket burn in the picture below, in which direction did the back end of the shuttle shift? direction did the back end of the shuttle shift?

A) Up and to the rightA) Up and to the right B) Down and to the rightB) Down and to the right C) Straight downC) Straight down D) Down and to the leftD) Down and to the left E) Up and to the leftE) Up and to the left

ConcepTest!ConcepTest!

• Major Orbit ModificationMajor Orbit Modification

Ear

thE

arth

AstronauticsAstronautics

AstronauticsAstronautics• Major Orbit ModificationMajor Orbit Modification

AstronauticsAstronautics

In the last example a satellite is moved from a lower orbit to a In the last example a satellite is moved from a lower orbit to a higher orbit by firing its rockets. In which orbit is the satellite higher orbit by firing its rockets. In which orbit is the satellite moving faster?moving faster?

A) The original low-earth orbit.A) The original low-earth orbit. B) The final higher-earth orbit.B) The final higher-earth orbit. C) Depends on how long the rockets fire.C) Depends on how long the rockets fire. D) Depends on the mass of the satellite.D) Depends on the mass of the satellite.

ConcepTest!ConcepTest!

AstronauticsAstronautics

AstronauticsAstronauticsE

arth

Ear

th

• Major Orbit Modification - ReentryMajor Orbit Modification - Reentry

AstronauticsAstronautics

For shortest reentry time, how would you want to fire your For shortest reentry time, how would you want to fire your rockets?rockets?

A) Opposite the direction of motion to slow the rocketA) Opposite the direction of motion to slow the rocket B) Opposite the direction of motion to stop the rocketB) Opposite the direction of motion to stop the rocket C) Opposite the direction of motion until rocket is moving inC) Opposite the direction of motion until rocket is moving in the opposite directionthe opposite direction D) In the direction of motion to increase the rocket speedD) In the direction of motion to increase the rocket speed

ConcepTest!ConcepTest!

AstronauticsAstronautics

• Escape from EarthEscape from Earth

AstronauticsAstronautics• Escape from EarthEscape from Earth

• Escape Velocity - Minimum speed at which two objects willEscape Velocity - Minimum speed at which two objects will not be held together by their mutual gravitynot be held together by their mutual gravity

• Note: An object Note: An object NEVERNEVER leaves the gravitational influence leaves the gravitational influence of another objectof another object

• Escape Velocity from surface of Earth is 11.2 km/sec or 40,000 km/hrEscape Velocity from surface of Earth is 11.2 km/sec or 40,000 km/hr

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Vescape =2GM

R RM

Escape velocity from geosynchronous orbit isEscape velocity from geosynchronous orbit is

A) greater thanA) greater than B) the same asB) the same as C) less thanC) less than

the escape velocity from the surface of the Earth.the escape velocity from the surface of the Earth.

ConcepTest!ConcepTest!

AstronauticsAstronautics

• To The Moon ….To The Moon ….

AstronauticsAstronautics

• To The Moon ….To The Moon ….

QuickTime™ and aSorenson Video decompressorare needed to see this picture.

AstronauticsAstronautics

• To The Moon ….To The Moon ….