An Apollo Timeline

May 20, 2009

c. 130 BC—Hipparchus determines the diameter of and distance to the Moon with very good accuracy.

1609—Galileo observes craters and mountains on the Moon using a small telescope.  He publishes his findings in Sidereus Nuncius (Starry Messenger) in 1610.

Galileo's observations of the Moon and planets revolutionized Astronomy.

1609: Galileo's observations of the Moon and planets revolutionize Astronomy.

1651—Giovanni Baptista Riccioli publishes a detailed atlas of the lunar surface, identifies the seas (maria), and begins the tradition of naming craters for astronomers and philosophers.

1687—Isaac Newton publishes Philosophiæ Naturalis Principia Mathematica (Mathematical Principles of Natural Philosophy), containing the three laws of mechanics, the law of universal gravitation, and derivations of Kepler’s laws of planetary motion.

Isaac Newton created the branch of physics called mechanics.  His principles were used by NASA scientists to land Apollo 11 on the Moon.

1687: Isaac Newton creates the branch of physics called mechanics. His principles are later used by NASA scientists to land Apollo 11 on the Moon.

1865—Jules Verne publishes From the Earth to the Moon, the first practical description of a manned lunar mission.

Jules Verne essentially invented science fiction.  His novel <i>From the Earth to the Moon</i> gave the first practical treatment of a lunar mission, and inspired many of the scientists who layed the groundwork for the Apollo missions.

1860s: Jules Verne essentially invents science fiction. His novel From the Earth to the Moon gives the first practical treatment of a lunar mission, and inspires many of the scientists who lay the groundwork for the Apollo missions.

1903—Konstantin Tsiolkovsky, inspired by Verne’s novel, publishes Exploring Space with Reactive Devices, laying the foundation for much of modern rocket science.  He describes the use of multi-stage rockets.

1906—H.G. Wells publishes The First Men in the Moon.

1920—Robert Goddard publishes A Method of Reaching Extreme Altitudes, describing both solid- and liquid-fueled rockets.

1923—Hermann Oberth, also inspired by Verne’s novel, publishes The Rocket into Interplanetary Space.  The book generates public interest in rocketry across Europe.

March 26, 1926—Working in secret, Goddard launches the first liquid-fuel rocket on a farm in Worcester, Massachusetts.  It reaches a maximum height of 41 feet.

Robert Goddard with the first liquid-fuel rocket, launched on March 26, 1926.

1926: Robert Goddard launches the first liquid-fuel rocket on a farm in Massachusetts. It reaches a height of 41 feet.

1927—Hermann Noordung develops the concept of a spinning space station shaped like a ring, with artificial gravity produced by the inertia associated with the spinning motion.

1927—The Verein für Raumschiffahrt (Germany’s Society for Space Travel) is founded by enthusiasts eager to put Oberth’s ideas to the test.  Club members, including Wernher von Braun, build small-scale rockets.

Wernher von Braun made significant contributions to the American space program.  His vision of a permanent American presence in space helped inspire the public's confidence in space exploration.

Throughout the 1950s and 60s, Wernher von Braun makes significant contributions to the American space program. His vision of a permanent American presence in space helps inspire the public's confidence in space exploration.

1929—Fritz Lang films Frau im Mond (Woman in the Moon), with Oberth as technical advisor.  With remarkable accuracy, Lang’s movie anticipates many of the modern elements of spaceflight, including the dramatic rollout of a huge vertical rocket, the “ten . . . nine . . . eight . . .” countdown, and the effects of low-gravity in space.  The movie has a profound influence on rocket scientists in Germany.

Fritz Lang's silent film <em>Woman in the Moon</em> had a profound influence on young rocket scientists in Europe.  The rollout of the massive vertical rocket (shown here) would be repeated with the Apollo missions a few decades later.

Fritz Lang's 1929 silent film Woman in the Moon has a profound influence on young rocket scientists in Europe. For example, the roll-out of the massive vertical rocket (shown here) will be repeated with the Apollo missions a few decades later.

1932 to 1944—von Braun works on rocket development for the German military.  His team develops the A-4, later renamed by Hitler the V-2.  Von Braun is arrested by the Nazi Gestapo in February 1944 for wasting time and money building rockets designed for space travel instead of for military applications.

The liquid-fueled V-2, designed by von Braun's team, was used by the German military to devestating effect in World War II.  But a solid-fueled rocket would have been more practical for military appliacations.

Early 1940s: The liquid-fueled V-2, designed by von Braun's team, is used by the German military to devastating effect in World War II. But a solid-fueled rocket would have been more practical for military applications.

1950—von Braun, working now for the Americans, redesigns the V-2 for improved guidance and larger payload.

1952 to 1954—in a series of articles published in Collier’s magazine, von Braun outlines an ambitious plan for space exploration, including permanent space stations, reusable shuttles and rockets, and manned missions to the Moon and Mars.  Several books are published outlining von Braun’s plans in greater detail, with breathtaking illustrations that capture the public’s imagination.

Writing for Collier's magazine, von Braun outlines an inspiring vision for a permanent American presence in space.  The lunar missions were to be only a part of a much larger program that would include permanent bases on the Moon and Mars.

1952 to 1954: Writing for Collier's magazine, von Braun outlines an inspiring vision for a permanent American presence in space. The lunar missions are only a part of a much larger program that includes permanent bases on the Moon and Mars.

March 9, 1955—Working closely with von Braun, Walt Disney televises Man in Space, watched by over 100 million Americans.  It is the first of three Disneyland broadcasts visualizing von Braun’s idea of a permanent American presence in space.

1956—von Braun and his team launch Missile 27 from Cape Canaveral in Florida.  It reaches an altitude of 680 miles, nearly high enough to put an artificial satellite into orbit.

1957—President Eisenhower approves a small U.S. satellite program, Project Vanguard.  The plan is for the satellites to measure the size and shape of the Earth.  Von Braun is not allowed to work on the project.

October 4, 1957—the Soviet Union launches Sputnik, the first artificial satellite.  Its repeating signal can be detected by anyone with a radio tuned to the correct frequency.  Three days later, Soviet premier Nikita Khrushchev informs a New York Times reporter that the Soviet Union possesses “every kind of missile necessary for modern war.”

Sputnik, launched the Soviet Union on October 4, 1957, was the first artificial satellite in space.

Sputnik, the first artificial satellite, is launched by the Soviet Union on October 4, 1957.

November 3, 1957—the Soviet Union launches Sputnik II, which carries a dog named Laika into space.  U.S. President Eisenhower, accused by frightened Americans of dragging his heals on space exploration, insists there is no “space race.”

Laika, the first animal launched into orbit by the Soviet Union on November 3, 1957.  Laika survived the launch and lived a few hours in space before dying from stress and heat.  (Soviet scientists had intended to euthanize her with poisoned food.)  Her death sparked animal rights' protests in the United States.

Laika is the first animal launched into orbit by the Soviet Union on November 3, 1957. After surviving the launch, she lives a few hours in space before dying from stress and heat. (Soviet scientists had intended to euthanize her with poisoned food.) Her death sparks animal rights' protests in the United States.

November 8, 1957—Eisenhower quietly gives von Braun and his team permission to continue working on rockets for space exploration.

December 6, 1957—at Cape Canaveral, the Vanguard rocket explodes on the launch pad.  The disaster is carried on live television.

While the Soviets were putting large satellites and live animals into space, the Americans were having serious problems.  The unmanned Vanguard rocket explodes on the launch pad, a disaster carried on live television!

December, 1957: While the Soviets are putting large satellites and live animals into space, the Americans are having serious problems. Here, the unmanned Vanguard rocket explodes on the launch pad, a disaster carried on live television!

January 31, 1958—von Braun’s team places the first American artificial satellite, the Explorer, into orbit.  Later, a second attempt to put the Vanguard into orbit is successful, followed by a second Explorer satellite.  Each of the American satellites is small, about the size of a baseball or volleyball.

May 15, 1958—the Soviet Union places the 3,000 pound Sputnik III into orbit.

October 1, 1958—Eisenhower creates the National Aeronautics and Space Administration (NASA), to keep civilian space exploration separate from military missile programs.  NASA initiates Project Mercury; its goal is to put an American in space.

NASA_logoNASA is created by President Eisenhower in 1959. Follow this link to learn more about the famous NASA logo.

April 9, 1959—the Mercury Seven, seven test pilots who have passed NASA’s rigorous training program for space flight, are introduced to the public.  They are Scott Carpenter, Gordan Cooper, John Glenn, Gus Grissom, Wally Schirra, Alan Shepard, and Deke Slayton.

The Mercury 7.

The Mercury 7.

November 8, 1960—John F. Kennedy is elected the 35th President of the United States.

Kennedy's challenge to put a man on the Moon by the end of the decade inspired the Apollo missions.

Kennedy's challenge to put a man on the Moon by the end of the decade inspires the Apollo missions.

April 12, 1961—the Soviet Union launches the Vostok, carrying Yuri Gagarin, the first human in space.  Gagarin spends 108 minutes completing the first manned orbit of the Earth.

Soviet cosmonaut Yuri Gargarin was the first person in space.  He spent 108 minutes orbiting the Earth.

Soviet cosmonaut Yuri Gargarin is the first person in space on April 12, 1961. He spends 108 minutes orbiting the Earth.

May 5, 1961—the first manned Mercury flight carries Alan Shepard to an altitude of 115 miles above the Atlantic Ocean.  Shepard spends five minutes at maximum altitude, becoming the first American in space.

Alan Shepard was the first American space, on May 5, 1961.

Alan Shepard becomes the first American in space, on May 5, 1961. He spends five minutes maximum altitude (115 miles).

May 25, 1961—in a speech to a joint session of Congress, President Kennedy delivers the somber challenge: “I believe this nation should commit itself to achieving the goal, before the decade is out, of landing a man on the Moon and returning him safely to the Earth.  No single space project in this period will be more impressive to mankind, or more important for the long-range exploration of space, and none will be so difficult or expensive to accomplish.”

January 10, 1962—NASA approves final designs for an advanced Saturn-series rocket, the Saturn V.  Von Braun will oversee development of the Saturn V at the Marshall Space Flight Center in Huntsville, Alabama.

The Saturn V, the massive three-stage rocket that would carry the Apollo astronauts into space.

Early 1960s: The Saturn V, the massive three-stage rocket that would carry the Apollo astronauts into space, is designed and built in Huntsville, AL by von Braun and his team.

February 20, 1962—John Glenn becomes the first American to orbit the Earth, completing three orbits aboard a Mercury space capsule.

John Glenn becomes the first American to orbit the Earth, on February 20, 1962.

John Glenn becomes the first American to orbit the Earth, on February 20, 1962.

June 16, 1963—the Soviet Union launches the Vostik VI, carrying the first female cosmonaut, Valentina Tereshkova, into space.

On June 16, 1963, Soviet cosmonaut Valentina Tereshkova becomes the first woman to orbit the Earth.

On June 16, 1963, Soviet cosmonaut Valentina Tereshkova becomes the first woman to orbit the Earth. The United States will not put a woman into space until 1983 (Sally Ride).

October 12, 1964—the Soviet Union launches the Voskhod I, carrying three men, the most ever, into space.  The crew includes Vladimir Komarov, pilot; Konstantin Feoktistov, scientist; and Boris Yegorov, physician.

March 18, 1965—Soviet cosmonaut Alexi Leonov becomes the first person to spacewalk, spending ten minutes outside the Voskhod 2.

Soviet cosmonaut Alexi Leonov becomes the first person to exit a spacecraft for a spacwalk, on March 18, 1965.

Soviet cosmonaut Alexi Leonov becomes the first person to exit a spacecraft for a spacewalk, on March 18, 1965.

June 3, 1965—Ed White becomes the first American astronaut to spacewalk.

December 4, 1965—the Gemini 7 blasts off, carrying Americans Frank Borman and Jim Lovell into space for a two-week endurance test.

January 27, 1967—the crew of Apollo 1, Roger Chaffee, Gus Grissom, and Ed White, are killed by a fire in the command module.  In the wake of the tragedy, the command module and its hatch are completely redesigned.

The crew of Apollo 1 is killed by a cabin fire on January 27, 1967.  Left to right: White, Grissom, Chaffee.

The crew of Apollo 1 is killed by a cabin fire on January 27, 1967. Left to right: Ed White, Gus Grissom, Roger Chaffee.

December 21, 1968—Apollo 8 is launched, carrying Frank Borman, James Lovell, and William Anders.  It achieves lunar orbit on December 24.

March 3, 1969—Apollo 9 is launched, carrying James McDivitt, David Scott, and Russell Schweickart.  They conduct a full test of the lunar module while in Earth orbit.

May 18, 1969—Apollo 10 is launched, carrying Thomas Stafford, John Young, and Eugene Cernan.  This is the first Apollo mission carrying all the equipment needed for a lunar landing, including the command and service modules, and the lunar module.  In a dry run for Apollo 11, the crew of Apollo 10 carry out all aspects of the Moon mission except for landing on the Moon.

July 16, 1969—Apollo 11 is launched at 9:32:00 AM Eastern Time, carrying Neil Armstrong, Michael Collins, and Edwin “Buzz” Aldrin.  The lunar module, the Eagle, lands on the Moon in the Sea of Tranquility at 4:17:40 PM on July 20.  Neil Armstrong steps onto the lunar surface at 10:56:15 PM, stating “That’s one small step for man, one giant leap for mankind.”  Aldrin joins him on the lunar surface twenty minutes later.  Armstrong and Aldrin spend 21 hours and 36 minutes on the lunar surface (including time spent in the Lunar Module).  The crew returns to Earth at 12:50:35 PM on July 24.

The crew of Apollo 11.  Left to right: Neil Armstrong, Michael Collins, Buzz Aldrin.

The crew of Apollo 11. Left to right: Neil Armstrong, Michael Collins, Buzz Aldrin. Armstrong and Aldrin become the first men on the Moon, July 20, 1969.

November 14, 1969—Apollo 12 is launched, carrying Charles Conrad, Jr., Robert Gordon, and Alan Bean.  After landing in the Ocean of Storms, Conrad and Bean recover parts from the Surveyor 3 spacecraft which had landed on the Moon 2 ½ years earlier.

April 11, 1970—Apollo 13 is launched, carrying James Lovell, John Swigert, Jr., and Fred Haise, Jr.  On April 14, an explosion and rupture of an oxygen tank causes a nearly catastrophic loss of oxygen, water, and electrical power in the service module.  The accident nearly kills the crew, and the planned lunar landing at Fra Mauro crater is aborted. The crew returns safely to Earth on April 17.

An entire panel of the Apollo 13 command module was blown away when an oxygen exploded, nearly killing the crew.  The photo was made by the astronauts as the command module drifted away in space.

April 14, 1970: An entire panel of the Apollo 13 service module is blown away when an oxygen tank explodes. The resulting damage nearly kills the crew. This photo is made later by the astronauts as the service module drifts away in space.

July 26, 1971—Apollo 15 is launched, carrying David Scott, Aldred Worden, and James Irwin.  Scott and Irwin land at Hadley Rille on July 30.  This mission is the first to use the Lunar Roving Vehicle, an electric four-wheeled vehicle designed to operate in the low-gravity vacuum on the lunar surface.  The crew returns to Earth on August 7.

The Lunar Roving Vehicle was used by the astronauts of Apollo 15, 16, and 17 to move around quickly on the lunar surface.

The Lunar Roving Vehicle is used by the astronauts of Apollo 15, 16, and 17 to move around quickly on the lunar surface.

April 16, 1972—Apollo 16 is launched, carrying John Young, Thomas Mattingly II, and Charles Duke, Jr.  A malfunction in the command module nearly forces the crew to abort the lunar landing, but Young and Duke land in the Descartes highlands region on April 21.  The crew returns to Earth on April 27.

December 7, 1972—Apollo 17 is launched, carrying Eugene Cernan, Ronald Evans, and Harrison Schmitt.  Cernan and Schmitt land at Taurus-Littrow on December 11.  The crew returns to Earth on December 19.  Apollo 17 is the last manned mission to the Moon.

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Let’s Meet the Moon

May 15, 2009

The Moon is the Earth’s nearest celestial neighbor, and the only astronomical object visited by human beings. Because it is easy to see in the sky, the Moon has been known since the dawn of humanity. But for centuries many misconceptions about it persisted in people’s minds. For example, although they were able to calculate its diameter and distance from the Earth, the ancient Greeks believed the Moon was a perfectly smooth sphere. Even today, many people believe the full Moon can affect people’s behavior, a discredited idea that lives on in such words as lunatic and lunacy.

The full Moon

The full Moon, (Click for a larger image.)

The Moon orbits the Earth at an average distance of 384,400 kilometers.  The orbit is almost a perfect circle.  At its closest approach to the Earth, the Moon is 363,000 km away.  At its greatest distance, it is 406,000 km away.  The Moon’s orbital period, the time needed to complete one full orbit, is 27.3 days.  The Moon’s rotational period, the time needed to complete one full rotation on its axis, is also 27.3 days.  Therefore, from the Earth we always see only one side of the Moon’s surface.  Because of its slow rotation period, daytime on the Moon lasts about 3,200 hours (about 14 Earth days).  When the Sun goes below the Moon’s horizon, the lunar night lasts just as long.

When we compare the Moon to other moons in the solar system, we find that is very large compared to its parent planet (the Earth).  In fact, if humans lived on Mars, we would probably have classified the Earth and Moon as a double planet.  If the Moon were directly orbiting the Sun instead of orbiting the Earth, it would be considered a planet in its own right.

Earth and Moon photographed by a Japanese satellite.

Earth and Moon photographed by a Japanese satellite. (Click for a larger image.)

The Earth is 83 times more massive than the Moon, and the Earth’s radius (the distance from the center of the Earth to a point on the surface) is 3.7 times greater than the Moon’s radius.  Because of these differences in mass and radius, the strength of gravity is much weaker on the surface of the Moon than on the surface of the Earth.  A person who weighs 100 pounds on the Earth weighs only 17 pounds on the Moon.  In other words, gravity on the Moon is one-sixth as strong as it is on the Earth.  Because the Moon’s gravity is so much weaker than the Earth’s, the Moon has no atmosphere like the Earth.

The Earth and Moon shown with the correct scale.  The Moon's distance from the Earth is 60 times the Earth's diameter.  (Click for a larger image.)

The Earth and Moon shown with the correct scale. The Moon's distance from the Earth is 60 times the Earth's diameter. (Click for a larger image.)

You can make a scaled model of the Earth-Moon system using a basketball to represent the Earth and a baseball to represent the Moon.  The ratio of the diameters is nearly the same the as ratio for the real Earth and Moon.  To get the distance correct, you must place the baseball about 30 feet away from the basketball (about 30 times the basketball’s diameter).   When you set up your model, it may seem the Moon is too far away, but remember that the Moon is a huge object compared to human beings.  So when it appears in the sky, it seems to be closer to the Earth than it really is.

Since the Moon has no atmosphere, conditions on its surface are very different than those on the Earth’s surface.  In particular, the temperature on the Moon’s surface varies through a huge range, from -240 degrees F during the lunar night to +240 degrees F, hot enough to boil water, during the lunar day.

The Moon is only object in space whose surface features can be easily seen with the unaided eye.  With a good pair of binoculars or a good telescope, it’s possible to see craters and mountains on the lunar surface.  In fact, the first person to observe the lunar surface with a telescope, Italian scientist Galileo Galilei, surprised the scientific community in 1609 when he reported that the Moon’s surface was not perfectly smooth—this was the common belief at the time.

There are three types of features on the Moon’s surface.  First, there are thousands of craters formed from the impact of meteors against the lunar surface.  The smallest craters are only a few millimeters in diameter, while the largest are nearly 200 kilometers from edge to edge.  There is no geological activity on the Moon’s surface, no earthquakes (or “moonquakes”) and no volcanoes.  There is also no weather—no wind or rain—since there is no atmosphere.  Therefore, when a crater is formed on the lunar surface, it lasts essentially forever, unless it’s obliterated by a later meteor impact.  Craters formed on the Earth are wiped away by the combined effects of geological activity and weather.  Only the most recent craters are still visible on the Earth’s surface.

Daedalus, a crater on the far side of the Moon, is about 93 kilometers across, and 3 km deep.

Daedalus, a crater on the far side of the Moon, is about 93 kilometers across, and 3 km deep. This photo was made by the Apollo 11 astronauts. (Click for a larger image.)

Another type of important feature on the lunar surface is the maria, the Latin word for “seas.”  These are large darkly-covered regions that to many people appear to be large seas or oceans.  But there is no liquid water anywhere on the Moon.  (There may be small amounts of ice at the Moon’s north and south poles.)  One of the maria, the Sea of Tranquility, is where Neil Armstrong and Buzz Aldrin first set foot on the Moon.  The Moon’s maria can be seen without a telescope.  It turns out there are no maria on the Moon’s far side, the side that always faces away from the Earth.

A list of the maria on the lunar surface, all of which are on the side of the Moon that faces the Earth.

A list of the maria on the lunar surface, all of which are on the side of the Moon that faces the Earth. (Click for a larger image.)

In addition to craters and maria, the lunar surface includes bright regions that resemble dry-land continents on the Earth.  These regions have much higher elevation than the maria (several kilometers higher), so they are called highlands.  Most of the Moon’s craters are in the highland regions.  The highlands are much brighter than the maria because they are composed of different kinds of rocks.

A list of the lunar highlands. (Click for a larger image.)

A list of the lunar highlands. (Click for a larger image.)

Moon rocks from the maria brought to the Earth by the Apollo astronauts are much younger than rocks from the Moon’s highland regions.  (The age of a rock is the length of time since it was last in a molten state.)  The age difference is as much as one billion years.  Because of this fact, and because there are many fewer craters in the maria compared to the highlands, astronomers believe the maria are relativly new features, probably formed by lava from beneath the Moon’s surface that smoothed away huge sections of its surface.  The lava was probably released by particularly violent meteor impacts that fractured the Moon’s surface and allowed the lava to pour out.

Where did the Moon come from?  Before scientists examined the rocks brought back by Apollo astronauts, there were three ideas: (1) the Moon formed elsewhere in the solar system and wandered close enough to the Earth to be captured into orbit by the Earth’s gravity, (2) the Earth and Moon formed simultaneously sort of like planetary twins, (3) in the remote past the Earth was spinning so fast some of its material was flung into space and formed the Moon.  But the lunar rocks brought back by the Apollo astronauts did not support any of these ideas.

Today, astronomers believe the Moon may have formed about 4.5 billion years ago when a planet approximately the size of Mars slammed into a very young Earth.  The impact was so violent that a huge amount of debris was flung into space, where it formed the Moon.  Detailed computer simulations have demonstrated that such a scenerio is possible, and the condition of the lunar rocks brought to Earth is consistent with this hypothesis.

Artist's conception of the impact 4.5 billion years ago that may have led the Moon's formation.

Artist's conception of the impact 4.5 billion years ago that may have led the Moon's formation.


Launching a Rocket to the Moon

May 7, 2009

July 20, 2009 is the 40th anniversay of Neil Armstrong’s historic first steps on the surface of the Moon.  To celebrate one of America’s greatest technological triumphs, I’m teaching a course this summer to local middle-school students in which they will launch a virtual rocket from low-Earth orbit toward the Moon.  My primary goal is to get kids excited about math and science.

This blog will be about all things related to the course.  Some articles will be about the history of the Apollo program, some will be about the basic math and physics of launching a rocket into space, and some will be about our computer program.  Most of what I’ll write here will be for the kids and their parents.  But I will include a few things at a more advanced level for physics teachers and other professionals.

apollo_11_insignia

Some technical details:

  • We’re using VPython to create a real-time, interactive, 3-D animation.  Students will work directly with the code, although they won’t be starting from scratch.
  • We’ll use a Verlet (leapfrog) integrator to update the forces between the Earth, Moon, and rocket.  These are the only three objects in the system.
  • The rocket will launch from a low-Earth equatorial orbit (200 km) and enter a nearly circular orbit about the Moon, about 4,000 miles above the lunar surface.  After about eight orbits, the rocket will return to Earth.
  • The animation is drawn to the correct scale (except for the rocket), with the Moon’s orbit having the correct semi-major axis and eccentricity.
  • In the end, the model leaves out a lot of important details.  Physicists, graduate students, and NASA engineers are welcome to comment on the articles, but remember this is a computer program written by and for kids in middle school.