Describing the “why”

1. Describing the “why” • Isaac Newton connected Kepler’s laws of planetary motion with his own insights into motion. • This united the disciplines of physics and astronomy. • Newton started with theory rather than observation.

2. Newton’s First Law • A body in motion tends to stay in motion unless acted upon by an outside force.

3. Newton’s Second Law • The acceleration of an object is proportional to the force acting on it and inversely proportional to the mass. • Mathematically: F=ma

4. Newton’s Third Law • Whenever one body exerts a force on a second body, the second body exerts an equal and opposite force on the first body.

5. Newton’s Third Law: Corollary • Conservation of angular momentum keeps planets in their orbits. • Depends on: • amount of mass • distribution of mass • rotation velocity.

6. Newton and Kepler • Kepler’s laws of planetary motion are just specific examples of Newton’s more general law of gravitation.

7. The results • Every object in the Solar System can be potentially predicted. • Comet Halley • Existence of Neptune and Pluto • Mars Climate Orbiter

8. An example • You = 50 kg. • Bullet = 1 g or 0.001 kg • Velocity of bullet = 1000 m/sec • To keep the total momentum of the original system zero, you have to acquire -1 momentum. • Since you weigh 50 kg, your velocity will be -1/50 or -.02 m/sec. • Your new speed = 2 centimeters per second backward.

9. Rockets and Momentum • A rocket ejects mass at high speed. • It thus acquires velocity in the opposite direction. • It does not need “something to push against.”

10. Orbits and Satellites

11. Early Rockets

12. Pioneers of rocketry • Goddard’s early model was the precurser of the Apollo lunar vehicle, the Saturn V.

13. World War II • The German attempt to create strategic rockets: the Vergeltungswaffe 1 and 2.

14. This is Rocket Science • First U.S. spy satellites, the Discoverer series (1960-) • Designed to take photos, drop film canisters for mid-air recovery. • Thirteen consecutive failures before success • Eventually evolved into standard U.S. space intelligence systems • Spy satellites key in keeping peace during the Cold War

15. Experimental aircraft • Chuck Yeager — first to break the sound barrier. • X-15 — highly successful experimental aircraft

16. The one that changed everything • Sputnik meant that the Soviets could reach us from anywhere in the world.

17. Strategy • Contained or hemmed in? It depends upon your point of view.

18. Exploration of the Universe Spaceflight 2: Vostok and Mercury, Voskhod and Gemini

19. A conspiracy revealed? • What’s wrong with this picture?

20. The Soviets Press On • Yuri Gagarin (one orbit) April 12, 1961 • Gherman Titov, August 6-7, 1961, more than 24 hours in orbit. • Andrian Nikolayev and Pavel Popovich, 1962; first two manned spacecraft to be simultaneously in orbit. • This series of spacecraft was called Vostok (Russian for "east", connoting sunrise).

21. More Soviet Firsts • In June, 1963, a second twin launch carried Valery Bykovsky and Valentina Tereshkova into orbit. • Tereshkova became the first woman into space, and the last for two decades.

22. And Still More • In 1964 the Soviets launched the first of the Voskhod (meaning "ascent") multi-person spacecraft. • Three cosmonauts orbited on Voskhod 1 in 1964 • Two orbited on Voskhod 2 in 1965. One of these, Alexei Leonov, made the first space walk.

23. Project Mercury 1961-63 • U.S. response: adapt a space capsule to an existing missile. • The first series of U.S. manned space missions was called Mercury. • Nobody had a clue what qualities would be necessary to travel in space. • Military test pilots were chosen. • Two suborbital flights • Four orbital flights (3-22 orbits)

24. Project Gemini, 1965-66 • Two-man craft • Ten flights up to 14 days long • First (and only) U.S. rendezvous (Gemini 6 and 7) • First emergency landing, also first Pacific landing (Gemini 8) • Altitude record (Gemini 11, 1370 km)

25. The Mercury capsule was meant to do one thing: get us into space. The Gemini missions were much more ambitious and were designed to be stepping stones to the Moon.

26. Going to the Moon As of September 30, 1998, 400 individuals from 25 countries had flown in space.

27. Russians to the Moon • In 1959 Luna II became the first spacecraft to strike the Moon. • In 1960, Luna III returned the first (very crude) pictures ever of the Moon’s far side. • 1966-68: First lunar soft landing, lunar rover and sample-return mission.

28. Did the Russians ever have a serious manned lunar program? • Critics: a myth to sustain NASA through the use of cold war hysteria. • In early 1990’s artifacts from the supposedly nonexistent Soviet lunar program, including lunar spacesuits, went on sale at Sotheby's in New York.

29. Did the Russians ever have a serious manned lunar program? • Several catastrophic explosions of the Soviet lunar rocket booster made it clear that they would not beat the U.S. to the moon. • Failure probably due to cutting corners and false economizing (i.e. faster, better, cheaper?)

30. Did the Russians ever have a serious manned lunar program? • Author James Oberg calls continued denial of a Soviet lunar landing program a "cover-up".

31. Kennedy’s Challenge • U.S. had 15 minutes’ experience in space when Kennedy proposed a race to the Moon. • Reason: would require both sides to develop new technology • Would be a level playing field

32. U.S. Robots to the Moon, 1963-68 • Ranger series: designed to impact the Moon, returning pictures on the way. • Only last three of nine worked, but results were spectacular. • Surveyor soft-lander series; most of the seven worked well. • Five Lunar Orbiter missions mapped almost all of the Moon. • First pictures ever of the Earth rising above the lunar horizon.

33. Tragedy for the Russians • Vladimir Komarov, on Soyuz 1, 1967, was Russia's first two-time space traveler. In 1967 • His parachute failed on re-entry; first space traveler to be killed. • Soyuz 11, 1971, lost pressurization on reentry; three-man crew died from lack of oxygen.

34. Tragedy at the Cape • On January 26, 1967, astronauts Gus Grissom, Ed White and Roger Chaffee were killed in a fire. • The Apollo Program was delayed for 18 months while equipment and procedures were redesigned.

35. Apollo Gets Off the Ground • Apollo 7, October 11, 1968, was first launch of a manned Apollo capsule into orbit. • Decision was made to reverse the order of the next two missions • Apollo 8: lunar flyby and return. • Live broadcast from lunar orbit on Christmas Eve, 1968.

36. More Rehearsals • Apollo 9 in Earth orbit, was a test of the lunar module. • Apollo 10, a return to the Moon, practiced maneuvering the lander in lunar orbit but did not touch down.

37. The Eagle Has Landed • At 4:17:41 P.M. (EDT) on July 20, 1969, an estimated 500 million people watched worldwide as Apollo 11 touched down on the Moon, confirmed by the message: "Tranquility Base here. The Eagle has landed." • 6-1/2 hours later, Neil Armstrong became the first human to set foot on the moon.

38. Houston, We’ve Had a Problem • Apollo 12 landed near the site of the Surveyor 3 lunar lander as a test of pinpoint lunar navigation. • Apollo 13: side of the lunar service module blew out halfway to the Moon and only heroic innovations on the ground and in space got the crew back.

39. Apollo Science • Apollo 14: first to explore lunar highlands. • Apollo 15: first to use the lunar rover. • Apollo 16 made three rover expeditions totaling 27 km. • Apollo 17 made three rover expeditions lasting 22 hours and travelling 35 kilometers.

40. End of Apollo • Apollo astronauts John Young (10, 16), Eugene Cernan (10, 17), and Jim Lovell (8, 13) each made two lunar flights. • No one has actually set foot on the Moon twice. • September 2, 1970: Apollo 18-20 cancelled. • We just quit.