SP200: Lectures 1-2

Student Learning Outcomes

Understand the early concepts of space exploration.
Able to formulate Kepler’s and Newton’s laws.
Reason the evolution of space exploration and rocketry in modern physics, and their main contributors.
Understand the various technologies and missions that evolved within the Space Race era.

Thales of Miletus (624 - 546 BC):
- Recognized for his accurate observations of solar eclipses.
Aristotle (384 - 322 BC):
- Promoted the geocentric model of the universe.
Aristarchus of Samos (310 - 230 BC):
- Developed the first heliocentric concept of the universe.
Eratosthenes (~240 BC):
- Measured Earth’s circumference with 1% accuracy.
Hipparchus (190 - 120 BC):
- Created the first star catalog and calculated celestial distances and diameters.
- His models were later validated by ESA’s Hipparchos satellite (1989-1993).
Antikythera Mechanism (100 BC):
- Recognized as the first known analog computer.

Ptolemy’s Almagest: Dominated the geocentric model for approximately 1400 years.
Tyco Brahe (1470 – 1730):
- His precise solar system observations supported Copernicus, Kepler, and Newton's theories.
Nicolaus Copernicus (1473 – 1543):
- Established the Sun as the center of the solar system, igniting controversy with the Church.
Galileo Galilei (1564 – 1642):
- Defended heliocentrism and faced house arrest due to Church disapproval.

Johannes Kepler (1571 – 1630):
- Formulated critical dimensions of the solar system and celestial body interactions.
- Developed the three laws of planetary motion:
1. Law of Orbits: Planets orbit the Sun in elliptical paths with the Sun at one focus.
2. Law of Areas: A line segment joining a planet and the Sun sweeps out equal areas during equal intervals of time.
3. Law of Harmonies: The square of the orbital period of a planet is proportional to the cube of the semi-major axis of its orbit:
  P^2 = a^3

Notable findings include:
1. Inner planets exhibit orbital phases like the Moon.
2. Jupiter has four significant moons (Galilean moons).
3. The Milky Way consists of numerous stars.
4. The Moon has mountains and valleys similar to Earth.

Isaac Newton (1642 - 1726):
- Authored Principia Mathematica (1687) establishing foundational laws of motion.
- Developed three laws of motion:
1. First Law (Law of Inertia): An object at rest remains at rest, and an object in motion maintains its velocity unless acted upon by an external force.
2. Second Law: The acceleration of an object is directly proportional to net force and inversely proportional to its mass:
  F = ma
3. Third Law: For every action, there is an equal and opposite reaction.

Chinese Gunpowder Rockets (~13th century): Early precursors to modern rocketry.
Konstantin Tsiolkovsky (1903): Developed the rocket equation, foundational for modern rocketry.
Robert Goddard:
- Launched the first liquid fuel rocket on March 16, 1926, in Auburn, Massachusetts, achieving an altitude of less than 200 meters.
- Invented and patented systems for guided rocket flight, influencing future space exploration and enabling NASA’s early rocket technology.

Wernher von Braun and the V-2 (1942):
- Became the first long-range guided ballistic missile and the first object to reach space.
- Introduced advanced technologies and design elements critical for future rockets.
Post-WWII Events:
- Operation Paperclip led to the integration of German scientists, including von Braun, into U.S. space programs and military R&D.

1946 - 1958:
- U.S. and USSR rivalry reflected in rapid advancements in rocketry and satellite technology, culminating in the Sputnik launches (1957), which shocked and spurred U.S. efforts in space.

Launch of Sputnik 1 on October 4, 1957, marked the start of the Space Race.
Launch of Explorer 1 on January 31, 1958, led to the discovery of the Van Allen radiation belts.
Introduction of NASA in 1958 marked a significant push for organized U.S. space exploration.
Between 1958-1981, a series of Explorer missions advanced our understanding of Earth and space.