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Tuesday, January 12, 2010

Figure 3.3a

Historical Astronomy


Figure 3.3b


Outline

• Ptolemy’s model of the universe

• Before Copernicus there was Aristarchus

• Kepler’s 3 laws

• Newton’s 3 laws

• What can we learn from these laws?

• The beginning of the space age .... Apollo


Figure 3.14Ptolemy’s geocentric model of the Universe

Click for Astrology


http://www.youtube.com/watch?v=oQPFoDkGFrU

http://www.youtube.com/watch?v=oQPFoDkGFrU

Show SkyGazer Mars


Figure 3.15 Annotated


Figure 2.33b Unannotated


Drawing by Carter Emmart, in David Grinspoon’s “Venus Revealed”


Unnumbered Figure 3.2





Aristarchus (310 - 230 BC)


Moon orbits every 29.5 days





d

87o



d20 x d

87o



d400 x d

0.5o


Actually ...


Unnumbered Figure 3.1 Annotated




At this point we need to introduce some planetary orbital mechanics

Kepler’s Three Laws of Motion: Law of Orbits, Law of Areas, Law of Periods

1. Kepler’s Law of Orbits: Planets orbit the sun in ellipses


Figure 3.18


Figure 3.19 Unannotated



Kepler’s 2nd Law

Planets orbit faster closer to the sun and slower farther from the sun


Figure 4.14a Annotated


3. Kepler’s Law of Periods:

P2 ∝ a3

For planets orbiting the Sunif a is in AU and P in years:

P2yrs= a3

AU

Earth: 1 AU, 1 year

Jupiter: 5.2 AU, 11.9 years

Neptune: 30 AU, what is P?


3. Kepler’s Law of Periods:

P2 ∝ a3

For planets orbiting the Sunif a is in AU and P in years:

P2yrs= a3

AU

Earth: 1 AU, 1 year

Jupiter: 5.2 AU, 11.9 years

Neptune: 30 AU, what is P?

€

Pyr = 303

= 9000=164yr







1) A body in motion will stay in motion, and a bodyat rest will stay at restuntil acted upon by a force.




2) Force = mass x accel.




2) Force = mass x accel.

3) For every applied force there is an equal and opposite force.




Figure 3.21 AnnotatedNewton used his equation to figure out the speed of the planets


Newton Revised Kepler’s 1st Law to describe the mutual

motion of two objects as they orbit

each other.



Newton re-wrote Kepler’s 2nd law to describe the exchange between kinetic and potential energy as planet traversed its ellipse





Figure 4.3 Unannotated






Figure 3.24


SkyGazer planet orbits.


• Kepler’s Laws:

1) Planets orbit follows an ellipse

2) Equal areas of the ellipse is swept out in equal times

3) p2 = a3

• Newton’s Laws:

1) Object in motion will stay in motion, and an object at rest will stay at rest until acted upon by a force

2) F = ma

3) For every force there is an equal and opposite force

Recap


Weightlessness in space is caused by the free falling spacecraft around Earth, not by a lack of gravity

The exchange of an object’s gravitational potential energy with kinetic energy results in Kepler’s second law. However total energy remains constant

Planets close to the sun travel faster than objects further away (Kepler’s third law).

Recap




Messenger Trajectory


http://www.youtube.com/watch?v=Ownzbb1mKxs

http://www.youtube.com/watch?v=Ownzbb1mKxs


Which side of a planet do you want to flybyif you want your spacecraft to speed up?



Which side of a planet do you want to flybyif you want your spacecraft to speed up?


Figure 4.21



On to the History of Spaceflight ...


Why Do We Need Rockets?• Modes of transportation on Earth won’t work in space• Wheels: no surfaces• Propellers: no atmosphere or liquid• Wings: no atmosphere• Jet engines: no atmosphere

Rockets that carry their own fuel on board and burn the fuel to move are required

Rockets use the principle of Newton’s 3rd Law (law of reciprocal actions)


Early SpaceflightIn the 1940s, Rolls Royce engineers concluded that spaceflight was impossible.

Rocket Equation (Konstantin Tsiolkovsky, 1903) based on Newton’s 3rd law of equal action-reaction:

€

mfinal = minitiale−Δv / vexhaust


Wernher von Braun(1912-1977)

• German rocket scientist• Helped develop the V2 ballistic missile for Nazis• At end of WWII, race between Soviets and US to recruit German rocket scientists• US Army had special units to find and recruit • von Braun surrendered to US and transferred to Fort Bliss, TX to work on US ballistic missiles• Became director of NASA’s Marshall Spaceflight Center in Huntsville, AL• Chief architect behind the Saturn V booster rockets


Wernher von Braun(1912-1977)

• German rocket scientist• Helped develop the V2 ballistic missile for Nazis• At end of WWII, race between Soviets and US to recruit German rocket scientists• US Army had special units to find and recruit • von Braun surrendered to US and transferred to Fort Bliss, TX to work on US ballistic missiles• Became director of NASA’s Marshall Spaceflight Center in Huntsville, AL• Chief architect behind the Saturn V booster rockets


V2 Rocket• Single stage rocket - used alcohol and liquid oxygen as propellant• Successfully tested first 1942 by Germany: flew 120 miles• Hitler assigned high priority to V2• By end of WWII, Germany had launched 3,000 V2s at England, France and Belgium

• First US V2 (built under direction of von Braun) launched 1946 in NM• Rockets then launched upwards• Achieved 65 miles altitude in late 1946 - camera attached• By early 1950s, V2s redesigned to carry payloadTuesday, January 12, 2010

Picture of V2


V2 Panorama

V-2 launched on March 7, 1947, took this picture from 101 miles up. The dark area is the Gulf of California.


The Space Race Begins

• USSR also had V2 technology• Called theirs the R1 missile• First launched successfully in 1948• Fifth generation missile R5 achieved ballistic range of 750 miles…


WAC Corporal

• US rocket project during WWII; similar size to V2• Designed and built at Jet Propulsion Lab, Pasadena• Used solid propellant rockets to get off the launch pad, then liquid propellant to go skyward.


Bumper WAC RocketThe first to space

• Result of pairing WAC Corporal and V2• World’s first 2-stage liquid-propellant rocket• Set altitude record in 1949 to 250 miles• Record launch was from what is know Kennedy Space Center, Cape Canaveral, FL


Multi-Stage Rockets

• Rolls Royce engineers concluded in 1940s that spaceflight was impossible• Their calculations were based on single-stage rockets• Single-stage rockets must carry entire payload, plus fuel and fuel tank into orbit• Currently no single-stage-to-orbit launch vehicles have ever been constructed – from Earth that is! Lunar module was launched from the Moon with a single stage rocket.• Multi-stage rockets can drop empty fuel tanks on the way up, lessening the weight


Intercontinental Ballistic Missiles

• Focus shifted back to ballistic missiles after nuclear technology progressed• By 1953, US had developed lightweight hydrogen bomb• Testing began in 1954• USSR had ICBM (R7) capable of hitting US by 1957


Sputnik• “The October Surprise”• October 4, 1957 USSR used an ICBM to put a satellite (Sputnik I) into orbit• Sputnik transmitted radio signals that could be heard all over the world• US was working on own satellite but was much smaller than Sputnik - US caught off-guard• Big impetus for US space program and science in general• Some say this is the real beginning of the Space Race


Picture of Sputnik

Sputnik was a bit bigger than a basketball and weighed 183 pounds


The Second Blow

•Sputnik II launched just a month after Sputnik I and was much larger!• Sputnik II carried the first space passenger: Laika the dog• Between 1958 and 1961, 6 more Sputniks were launched, each larger than the last…


The US Replies

• In January 1958, the US launched Explorer I on a modified Jupiter-C rocket (then called Juno I)• Juno I was a 3-stage rocket developed by von Braun and team• Explorer I was developed at JPL• Explorer I had scientific payload that studied Earth’s radiation belt (Van Allen Belt)


NASA

• Up until 1958, Department of Defense had been managing rocketry, under the auspices of the National Advisory Committee on Aeronautics (NACA).• After Sputnik, pressure mounted to show that we were not at a technological disadvantage with USSR• Congress passed the National Aeronautics and Space Act in July 1958, which founded the National Aeronautics and Space Administration.


Luna• In 1959 the USSR launched Luna 3, which orbited the moon and took the first pictures of the far side of the moon


Yuri Gagarin

• April 12, 1961, Soviet cosmonaut Yuri Gagarin became first human in space• Circled the earth once and returned safely• Occurred 1 month before Shepard’s suborbital flight and 10 months before Glenn’s orbital flight• This flight sent message to the US: USSR is way ahead in the Space Race• Check out Yuri’s Night, the “Cinco de Mayo of space”.


http://yurisnight.net/

http://yurisnight.net/

Mercury Program"I believe that this nation should commit itself to achieving the goal, before this decade is out, of landing a man on the Moon and returning him safely to the Earth.” President John F. Kennedy, 1961.

• 1958-1963, US’s first manned spaceflight program• Goals: to orbit a manned spacecraft around Earth, to investigate man’s ability to function in space, and to recover both man and spacecraft safely• 20 unmanned flights between 1959 and 1961• 7 astronauts chosen• 6 manned flights between 1961 and 1963


Animal Astronauts• NASA began sending monkeys into space in 1959• 4 of Mercury launches were “manned” by monkeys


Mercury Astronauts

• 1961: Alan Shepard became first American to make suborbital space flight• 1962: John Glenn became first American to orbit Earth• 1963: Gordon Cooper became first American to spend an entire day in space


More Soviet Firsts• 1962: First two-spacecraft mission• 1963: First multi-day mission (5 days in orbit)• 1963: Valentina Tereshkova became first woman in space


http://www.astronautix.com/astros/terhkova.htm






Spacewalking

• 1965: Aleksei Leonov became first human to go outside spacecraft• Spent 20 minutes spacewalking• Suit overinflated and had to vent it to get back inside spacecraft• Later the same year, Edward White became first American to spacewalk



Gemini Program• 1964-1966• One goal was to have 2-man long-duration flights• 2 unmanned flights• 10 manned missions• Improved spacecraft control techniques• Rendezvous and docking• First US spacewalk• 1965: astronauts Borman and Lovell spent record-breaking 14 days in space


Soviet Lunar Program• Zond circumlunar missions 1965-1970• 1968: Zond 5 became first probe to loop around moon and return to Earth• Soyuz and Kosmos missions tested lunar spacecraft and maneuvers 1966-1969• L3 “man-on-the-moon” mission scheduled for 1968 but never executed• Lunokhod missions landed rovers on the moon: took pictures and analyzed rock and soil 1970-1973• BUT… USSR didn’t have a powerful enough launch vehicle for manned mission to moon


Saturn V Rocket

• Developed at NASA’s Marshall Spaceflight Center under direction of Wernher von Braun• 3-stage rocket• Taller than a 36-story building• Biggest, most powerful rocket ever launched• 15 Saturn Vs were built• Never failed


US Lunar Reconnaissance• 1961-1965: Ranger missions to first close-up pictures of moon• 1966-1968: Surveyor missions landed on the moon and conducted soil tests• 1966-1967: Lunar Orbiter missions mapped possible landing sites


Apollo Program

• 1968-1972• 6 unmanned missions• 12 manned missions• Apollo 8: first manned lunar orbital mission; took first pictures of Earthrise• Apollo 9: first manned flight of lunar module• Apollo 10: dress rehearsal for lunar landing; partial descent to moon


Tragedy on the Launchpad• January 1967: Apollo 1 burns on the launchpad, killed 3 astronauts• Manned flights halted for almost 2 years while Apollo capsules were redesigned• April 1967: Soviet Soyuz 1 had parachute failure, crash landed and killed 1 cosmonaut• USSR halted manned flight for 18 months


Soviet Lunar Sample Return?• Soviets realized they couldn’t beat US to land man on the moon• Instead sent robotic mission to collect and return moon rocks and soil to Earth ahead of astronauts return• Luna 15 spacecraft crash landed on the moon


The Moon Landing• July 20, 1969• Apollo 11: Neil Armstrong, Buzz Aldrin, Michael Collins


The Moon Landing• July 20, 1969• Apollo 11: Neil Armstrong, Buzz Aldrin, Michael Collins


Other Apollo Missions

• 1969, Apollo 12: landed on moon, retrieved parts of Surveyor 3 which landed on moon in 1967• 1970, Apollo 13: supposed to land on the moon but had oxygen tank leak - had to circle around moon and fly straight home• 1971, Apollo 14: Deployed science instruments, gathered rocks• 1971, Apollo 15: First of the long-duration stays on lunar surface, drove Lunar Roving Vehicle on the moon• 1972, Apollo 16: First study of lunar highlands, used UV camera on surface• 1972, Apollo 17: First scientist-astronaut landed on moon



Moon Hoax?• 800 kg of rocks returned from the Apollo missions

Spherical glass beadsRadiometric age dates ~ 3.8 GaCosmic ray-generated isotopes Micro-meteorite impactsLaser reflectometer used to measure the moon’s distance


Moon Hoax?• 800 kg of rocks returned from the Apollo missions

Spherical glass beadsRadiometric age dates ~ 3.8 GaCosmic ray-generated isotopes Micro-meteorite impactsLaser reflectometer used to measure the moon’s distance




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