Return Flight from the Moon

On July 20, 1969, the Apollo 11 reached the Moon. Millions watched as Neil Armstrong and Buzz Aldrin took their first steps on the surface. The United States had reached the Moon before the Soviet Union, and the first part of President Kennedy’s objective to the nation, of “landing a man on the moon and returning him safely to the earth,” had been fulfilled.

Now the three-man crew needed to get home.

Image courtesy of

After jettisoning the Lunar Module Eagle shortly before leaving lunar orbit and intentionally breaking off from the Service Module during the beginning of reentry, all that remained of the Apollo 11 craft was the Command Module Columbia, a truncated cone shorter than 11 feet in height (the Saturn V rocket that launched the Apollo 11 into space was over 300 feet tall).  Columbia served as the crew quarters for the entire flight and housed most of the spacecraft systems, including the Earth Landing System. Michael Collins had stayed aboard Columbia in lunar orbit while Armstrong and Aldrin used Eagle to explore the Moon’s surface.

Columbia would have to put up with great temperature change during the mission; from the heat of launching from the earth’s surface to the cold of space, to taking on the direct heat of the sun, as well as the extreme heat of reentry. The temperatures would range between 280 degrees below zero and 5000 degrees above. To combat the temperature extremes, an ablative heat shield was used around the entire command module. The heat shield was designed to melt and erode away with the rising temperatures, taking the heat with it.

This heat shield was also covered with Kapton tape for added insulation. Developed by DuPont, Kapton is a polyimide film that is capable of withstanding extreme temperatures and hold up in these conditions. Kapton material was also used on the lunar module, as well as the astronauts’ spacesuits. Kapton is still used today for microelectronics, including flexible electronics and smartphones.

The chemical structure of Kapton. Image courtesy of Wikipedia.

As Columbia reentered the Earth’s atmosphere, it would appear on the outside as if the module was in a ball of flame, but on the inside, the astronauts were safely protected from the heat as it was repelled away with the melting shield. Columbia dropped into the Pacific Ocean on July 24, 1969, just before dawn local time. All three astronauts returned safely to the Earth.

While a lot of the heat shield and Kapton material burned up, a fair amount of it did survive reentry. Limited quantities of Kapton foil from the lunar missions have been known to go on sale. Interested buyers are always encouraged to make sure such items include certificates of authenticity when looking to own a little piece of history. It’s a marvel of technological advancement that such a thin reflective foil could make the difference between life and death for these intrepid explorers.

A collectible remnant of the Kapton foil from the Apollo 11 Command Module, which includes Certificate of Authenticity. Available for a limited time at Edmund Scientifics.

Time Capsule in the Stars: Exploring Voyager 1’s Golden Record

Artist concept of the Voyager probe in space. Image courtesy of NASA/JPL-Caltech

Earlier this month, NASA announced that the Voyager 1 probe had successfully entered interstellar space; the first human-made object to do so. As the probe continues forth into the vast unknown, it carries with it a special collection of “welcome signs” for any life forms it may encounter. Known as the Voyager Golden Record, this 12” gold plated copper disc was designed to operate similarly to a phonograph record. The disc is filled with sounds and images from Earth. Carefully selected by a committee led by Dr. Carl Sagan of Cornell University, the Voyager Golden Record includes the following:

  • Sounds from nature, including thunder and wind, and animals such as whales and birds
  • 55 spoken greetings in various Earth dialects, both ancient and modern
  • Printed messages from US President Jimmy Carter and UN Secretary General Kurt Waldheim
  • A 90-minute collection of music from various cultures
  • 115 images from Earth

Both the Voyager 1 and Voyager 2 probes carry a copy of the Voyager Golden Record. The record was designed to be played at a speed of 16 2/3 rotations per minute; half the speed of traditional vinyl records. Not to leave the greeting without an instruction manual, NASA meticulously crafted a cover for the record, using a collection of images and binary code to provide the proper setup needed to play the record that would transcend any language barrier. A stylus is included with the record to allow for it to be played.

A replica of the Voyager Golden Record cover, available at Edmund Scientifics. The record’s cover utilizes images and binary arithmetic to decipher instructions for playing the record.

The upper left portion of the record’s cover shows visual directions for how to properly play the record, including placement of the stylus to the record, playing from the outside of the record to the inside, and the speed at which to play the record. The lower left portion features a pulsar map, previously included on plaques for Voyager’s predecessors, the Pioneer 10 and 11 probes. The map shows the position of the sun in relation to 14 different pulsars. The upper right portion shows how to extrapolate the images from the disc, using the signal, which decodes to a series of 512 vertical lines. It also includes an image of a circle, the first image used to verify that the images have been decoded correctly. The time scale with which to use as reference is the final piece of the puzzle, showcased in the image on the bottom right. Instead of relying on seconds and minutes (derived from Earth’s rotation), the code on the Golden Record relies on the fundamental transition of the hydrogen atom (approximately 0,70 billionths of a second) as the preferred time scale.

While the likelihood of encountering intelligent life along Voyager 1’s current trajectory may be minimal (even equated by Dr. Sagan as tossing a “bottle into the cosmic ocean”), the Golden Record serves as a conscientious time capsule of tiny blue dot that is the planet Earth.

Voyager Fun Facts:

  • Despite their numerical ordering, Voyager 1 was actually launched 16 days AFTER Voyager 2. Voyager 2 launched on August 20, 1977, with Voyager 1 launching September 5. Voyager 1’s trajectory varied from Voyager 2, with Voyager 1 planned to reach Jupiter and Saturn first.
  • While the Voyager program only consisted of two probes, the 1979 film Star Trek: The Motion Picture uses a fictionalized continuation of the program (a NASA probe designated Voyager 6) as a main plot point.
  • Traveling at the speed of light, a signal sent from Earth takes approximately 17 hours to reach Voyager 1 and 14 hours to reach Voyager 2.
  • Voyager 1’s power supply is very limited, and will have to shut down all instrument operation by the year 2025.