Science on This Day: December 13 | Relay 1, Apollo 17, and Philip Warren Anderson
December 13 brings together three events that helped shape modern communications, space exploration, and our understanding of materials. In 1962, Relay 1 launched to test how satellites could transmit communications around the world. In 1972, Apollo 17 astronauts carried out their final excursion on the lunar surface, marking the closing chapter of the last crewed Moon landing mission to date. And in 1923, physicist Philip Warren Anderson was born. His research would help explain how electrons behave in real materials, including those whose internal structures are not perfectly ordered.
These stories offer different ways to bring physics and engineering into the classroom. They show how technology can extend communication across continents, how scientific exploration depends on careful observation and sample collection, and how theoretical physics can help explain the behaviour of the materials used in everyday electronics.
If you are looking for a quick way to introduce science history throughout the month, the December Science on This Day resource set includes 132 events across 31 days. It comes with an interactive HTML version, editable slides with discussion questions, a spreadsheet, and a printable PDF, so you can choose an event that fits your lesson or use one as a short daily starter.
Relay 1 launches: 13 December 1962
On 13 December 1962, NASA launched Relay 1, an experimental communications satellite designed to receive signals from Earth and retransmit them to other ground stations. It was part of a period of rapid experimentation with satellite communications, when engineers were investigating how spacecraft could help carry television broadcasts, telephone conversations, and other information over long distances.
Before communications satellites, transoceanic messages could travel through undersea cables or through radio systems that depended on atmospheric conditions. A satellite offered another approach. A ground station could send a signal upwards to a satellite, which would receive and amplify it before transmitting it back towards a receiving station. In this way, a satellite could help bridge the distance between places that could not communicate directly with one another.
Relay 1 was not the first communications satellite. Telstar 1 had launched earlier in 1962 and demonstrated transatlantic television transmissions. Relay 1 added to this early work by testing active signal relay in orbit and supporting experiments between North America, Europe, and South America. Its mission also demonstrated how satellite links could be used for television and other forms of communication across large distances.
The mission did not work perfectly from the start. An electrical problem caused excessive power drain shortly after launch, disrupting the satellite’s initial operation. Engineers traced the problem to a voltage regulator and were able to use a backup communications system. Relay 1 then went on to support successful experiments. The experience illustrates a key feature of engineering: a design can be promising, but the real test comes when it is operating in the environment for which it was built.
Relay 1 later contributed to important television transmissions, including the relay of broadcasts between Japan and the United States. In 1964, it also worked with another satellite, Syncom 3, to help relay television coverage of the Olympic Games in Tokyo. Using two satellites together demonstrated how a network of spacecraft could extend the reach of communications beyond what a single satellite could achieve.
Today, satellite communications support television, telephone connections, navigation services, emergency communications, and internet access in many parts of the world. Modern systems are much more capable than Relay 1, but they build on the same basic idea: receive a signal, process or amplify it, and transmit it to a destination where it can be used.
A classroom connection: how does a satellite relay a message?
Ask students to draw a simple communications system containing a transmitter, a satellite, and a receiver. They should add arrows to show the direction of the signal and explain why the satellite needs both receiving and transmitting equipment. You could then ask what might happen if the satellite loses power or its antenna cannot point in the right direction.
This provides an opportunity to discuss electromagnetic waves, energy transfer, and the difference between a passive reflector and an active communications satellite. Students can also compare the advantages and limitations of satellites with undersea cables, including coverage, delay, capacity, and the practical difficulty of installing and maintaining infrastructure.
For an extension, ask students to imagine how emergency services might communicate after a natural disaster damages roads and ground-based communication networks. What could a satellite link provide, and what limitations would engineers still need to consider?
Apollo 17: the final human walk on the Moon, 1972
Apollo 17 was the sixth and final Apollo mission to land astronauts on the Moon. Its Lunar Module, Challenger, touched down in the Taurus-Littrow valley on 11 December 1972. Commander Eugene Cernan and lunar module pilot Harrison Schmitt spent more than three days at the lunar landing site, while command module pilot Ronald Evans remained in orbit around the Moon.
Schmitt was a trained geologist, making Apollo 17 particularly valuable for lunar science. He became the first professional scientist to walk on the Moon. Alongside Cernan, he examined the local landscape, collected rock and soil samples, deployed scientific instruments, and used the Lunar Roving Vehicle to travel farther from the lander than would have been possible on foot alone.
On 13 December, Cernan and Schmitt began their third and final lunar surface excursion. The excursion continued into 14 December, when they completed their work and prepared to leave the surface. Cernan and Schmitt remain the last humans to have walked on the Moon. Their departure closed a remarkable period of human lunar exploration, although robotic spacecraft have continued to study the Moon since then.
The astronauts collected approximately 110 kilograms of lunar material during the mission. Those samples gave researchers the opportunity to examine the Moon’s history using laboratory equipment back on Earth. Some of the rocks revealed evidence of ancient volcanic activity, while other samples helped scientists investigate the impact processes that shaped the lunar surface. One memorable discovery was orange-coloured soil containing tiny volcanic glass beads, evidence of explosive volcanic activity long before the astronauts arrived.
Apollo 17 also demonstrated why scientific fieldwork requires more than simply visiting a location. Researchers need to identify useful sites, make observations, document where samples were collected, and select material that can help answer specific questions. The samples are still valuable because new analytical techniques can reveal details that earlier instruments could not measure.
The mission remains a useful example of the relationship between exploration and scientific investigation. The Moon is not simply a destination. It is a world with a geological history, and understanding that history requires evidence gathered from its surface, combined with observations from orbit and comparisons with other planetary bodies.
A classroom connection: what can lunar rocks tell us?
Show students images of the Apollo 17 landing site, lunar rock samples, or the orange soil discovered during the mission. Ask them to distinguish between observations and explanations. For example, “the sample contains small orange glass beads” is an observation, while “the beads formed during volcanic activity” is an explanation that needs evidence.
Students could then design a short investigation into how scientists might distinguish between a rock formed by volcanic activity and material created or altered by an impact. What features would they look for? What measurements might help? Why would it be useful to bring samples back to Earth?
This activity connects naturally with geology, the Solar System, and the scientific method. It also gives students a reason to discuss why collecting and preserving samples carefully matters for future research.
For another space-science activity, my Black Holes Strange But True facts and 2 Truths and a Lie resource encourages students to assess unusual claims and use scientific knowledge to decide which statements are reliable.
Philip Warren Anderson is born: 13 December 1923
Philip Warren Anderson was born in Indianapolis, Indiana, on 13 December 1923. He became one of the most influential theoretical physicists of the twentieth century, particularly through his work on the electronic structure of materials, magnetism, and the behaviour of electrons in disordered systems. In 1977, he shared the Nobel Prize in Physics for fundamental theoretical investigations of the electronic structure of magnetic and disordered systems.
Many introductory models describe solids as materials whose atoms are arranged in a regular pattern. In real materials, however, the structure can be more complicated. Some solids contain imperfections, mixtures of different atoms, or irregular arrangements. These differences can affect how electrons move through a material and, in turn, influence properties such as electrical conductivity and magnetism.
Anderson made a major contribution to understanding what happens when disorder affects electron movement. In a landmark paper published in 1958, he showed that disorder can cause electrons to become localised under certain conditions, meaning they do not move freely throughout a material. This work helped researchers understand why materials with different internal structures can have very different electrical properties.
His research belongs to condensed matter physics, the branch of physics that studies the properties of solids and liquids made from large numbers of interacting particles. It may sound distant from everyday experience, but condensed matter physics underpins much of modern technology. Understanding the behaviour of electrons in materials is essential to the development of semiconductors, magnetic devices, sensors, and many other electronic components.
Anderson’s career also demonstrates that progress in physics does not always come from building a new machine or conducting a dramatic experiment. Theoretical work can change how scientists interpret evidence and predict what materials will do. Those predictions can then guide experiments and the development of new technologies.
It is important not to suggest that Anderson single-handedly invented modern electronics. Semiconductor technology developed through the work of many scientists and engineers. His contribution was to deepen the theoretical understanding of how electrons behave in complex materials, helping researchers make sense of phenomena that simpler models could not explain.
A classroom connection: why do materials behave differently?
Ask students why copper is a good electrical conductor while rubber is commonly used as an electrical insulator. Their answers may include the movement of electrons, the structure of the material, and the way electrons interact with atoms. Anderson’s work offers a way to extend this discussion beyond the simplest models of conductors and insulators.
Students could compare how the internal structure of different materials might influence their properties. For older students, introduce the idea that electrons in a material do not always move freely, and that disorder can change how they behave. The goal is not to reproduce Anderson’s mathematics, but to recognise that microscopic structure can help explain macroscopic properties.
This is a useful link between physics and technology. The materials used in circuits, computer chips, and sensors are chosen because of their particular electrical properties. Understanding those properties requires both experimental investigation and theoretical models.
More science history to explore in December
December 14 offers two further opportunities to explore physics and space. In 1900, Max Planck presented work on blackbody radiation that helped introduce the idea of quantised energy, a foundation of quantum physics. On the same date in 1962, NASA’s Mariner 2 spacecraft flew past Venus, becoming the first spacecraft to complete a successful planetary flyby. Its measurements helped scientists understand the planet’s high temperatures and conditions.
On 15 December, the Soviet Venera 7 probe transmitted data from the surface of Venus after achieving the first successful soft landing on another planet. Its short transmission provided direct measurements from an environment with extreme heat and atmospheric pressure. The date also marks the birth of physicist Henri Becquerel in 1852, whose work on uranium salts led to the discovery of spontaneous radioactivity.
On 16 December, students can explore the invention of the point-contact transistor in 1947, a milestone in the development of solid-state electronics. The same date marks the birth of Arthur C. Clarke, whose writing about geostationary communications satellites anticipated an important idea for global communications. These events connect naturally to the Relay 1 story and the physics behind modern technology.
You can explore these and many more events in the December Science on This Day resource set. With 132 events available in interactive HTML, editable slides, a spreadsheet, and a printable PDF, it is easy to find a topic that connects with your current unit or gives students a different way into science. You can also browse the full Teaching Astrophysicist store for free and paid science teaching resources.
Relay 1, Apollo 17, and Philip Warren Anderson represent three different ways scientific knowledge grows. Engineers tested how satellites could carry messages across the world, astronauts gathered evidence from the lunar surface, and a physicist developed theories to explain how electrons behave in complex materials. Each event shows how science combines questions, evidence, instruments, and ideas to help us understand the world and develop new technologies.
Thanks for reading
Cheers and stay curious
Oliver - The Teaching Astrophysicist
