Science on This Day: 3 November | Nuclear Reactors, Laika and the First Mercury Mission
Science history provides teachers with a practical way to connect classroom concepts to real events, scientific decisions and technological developments. The events of 3 November offer three particularly useful starting points: the Oak Ridge X-10 Graphite Reactor reaching criticality in 1943, Laika's launch aboard Sputnik 2 in 1957, and NASA's Mariner 10 mission launching in 1973.
These stories connect nuclear physics with engineering, space exploration with biology, and planetary science with mathematics. They also raise questions that go beyond scientific facts. How does a nuclear reactor differ from a nuclear weapon? What responsibilities do scientists have when experiments involve animals? How can a spacecraft change direction without using extra fuel?
For middle and high school students, these questions help turn a short historical story into an opportunity to explain scientific principles, evaluate evidence and consider the consequences of technological progress.
3 November 1943: The Oak Ridge X-10 Graphite Reactor reaches criticality
On 3 November 1943, the X-10 Graphite Reactor at Oak Ridge reached criticality during the Manhattan Project. The reactor supported research and plutonium production, making it part of the scientific and engineering work associated with the development of nuclear technology during the Second World War.
The word criticality has a specific meaning in nuclear science. In a fission reactor, certain heavy atomic nuclei can split after absorbing neutrons, releasing energy and additional neutrons. A self-sustaining chain reaction occurs when, on average, each fission event leads to one further fission event. In a reactor operating at a steady power level, the chain reaction is controlled so that the rate of fission remains stable.
This makes nuclear reactors useful for studying energy transformations, nuclear reactions and the engineering systems needed to manage them. Reactor design involves more than producing a chain reaction. Engineers must also consider heat transfer, materials, radiation shielding, monitoring and control systems.
The X-10 reactor also provides a historical context for discussing the relationship between scientific research and military objectives. The Manhattan Project brought together scientists, engineers and technicians to develop nuclear technology during wartime. Students can investigate how discoveries in fundamental physics became part of large-scale engineering projects, and why the same underlying scientific knowledge can have different applications.
A useful classroom starting point is to ask: How does a nuclear reactor differ from a nuclear weapon? Students can compare their purposes, how their nuclear reactions are managed, and the engineering requirements involved. The goal is to help them distinguish controlled energy production from the rapid energy release associated with a nuclear weapon, rather than treating all nuclear technology as the same.
For a practical follow-up, students could draw a simple energy-transfer diagram for a nuclear power station. They can trace how energy released by nuclear reactions becomes thermal energy, how that energy can produce steam, and how a turbine-generator system converts it into electrical energy. Upper elementary students could focus on the sequence of energy transformations, while older students can investigate the role of the reactor's control and cooling systems.
The history of the X-10 reactor also offers an opportunity to discuss scientific responsibility. Students can consider how scientists and engineers assess risks, communicate limitations and make decisions when their work has consequences beyond the laboratory.
3 November 1957: Laika becomes the first dog to orbit Earth
On 3 November 1957, the Soviet Union launched Sputnik 2 carrying Laika, a dog who became the first animal to orbit Earth. The mission advanced early spaceflight knowledge, but it also raised lasting ethical questions about animal research and the risks associated with sending living organisms into space.
In the early years of space exploration, scientists needed to understand how living organisms responded to the conditions of spaceflight. A mission involving an animal could provide information about the effects of launch, acceleration, weightlessness and the spacecraft environment. Researchers had to consider how biological systems might respond to conditions that could not be fully reproduced in a laboratory on Earth.
However, Laika's mission also illustrates the distinction between what an experiment can teach and whether the methods used are ethically justified. Scientific research involving animals raises questions about potential benefits, welfare, suffering and the availability of alternative methods. These questions remain relevant in fields such as medicine, biology and space research.
This makes the story especially valuable for lessons that combine science with ethical reasoning. Students can learn about the historical context of the Space Race while considering how scientists decide which experiments should be conducted. They can also explore how standards for research ethics develop as scientific knowledge, technology and public expectations change.
A classroom discussion could begin with the question: How should scientists weigh potential benefits against animal welfare? Encourage students to identify the possible scientific value of an experiment, the risks to the animal, the quality of the evidence it might provide and whether alternatives are available. Students should support their reasoning with evidence and recognise that an ethical decision may involve competing considerations.
For a structured activity, ask students to work in small groups to develop criteria for evaluating a proposed research study involving animals. Each group could decide which questions must be answered before the study receives approval. They might consider whether the research addresses an important question, whether the methods are justified, how suffering could be reduced and whether non-animal approaches could provide the necessary information.
Younger students can explore the difference between caring for animals and using animals in scientific investigations, while older students can compare historical research practices with modern principles of research ethics. The emphasis should be on careful reasoning rather than assuming that scientific progress automatically justifies every method used to achieve it.
Laika's story also creates a link to the broader history of space exploration. Early missions helped researchers develop knowledge and technology that contributed to later human spaceflight. At the same time, remembering the living beings involved encourages students to consider the responsibilities that accompany scientific ambition.
Source: NASA: Sputnik.
3 November 1973: Mariner 10 launches towards Mercury
On 3 November 1973, NASA launched Mariner 10, a spacecraft that became the first to use a planetary gravity assist and the first spacecraft to visit Mercury. The mission is an excellent example of how mathematical models and the laws of physics can help engineers plan journeys through the Solar System.
Spacecraft need to change their velocity and direction to reach different destinations. Carrying enough fuel for every possible manoeuvre can be difficult because fuel itself adds mass, and additional mass affects launch requirements. Mission designers therefore look for ways to make use of the gravitational fields of planets and other celestial bodies.
A gravity assist involves a spacecraft passing near a moving planet in a carefully planned trajectory. From the perspective of the planet, the spacecraft's speed relative to the planet changes little in an idealised encounter. However, because the planet is moving around the Sun, the spacecraft can gain or lose orbital energy relative to the Sun. This can change its speed and direction along its solar orbit without requiring the spacecraft to use its engines for the entire manoeuvre.
The result depends on the spacecraft's approach, the planet's motion and the geometry of the encounter. Gravity assists require precise calculations and navigation, but they can make missions possible that would otherwise require more propellant or different launch plans.
Mariner 10's mission provides a useful way to connect Newton's laws of motion and universal gravitation with a real engineering problem. Students can investigate how gravitational forces influence motion, why planets are not stationary objects in space, and how engineers use mathematical models to plan spacecraft trajectories.
A useful discussion question is: How can a planet's gravity change a spacecraft's path without using extra fuel? Ask students to explain the difference between a spacecraft's motion relative to a planet and its motion relative to the Sun. This distinction helps them understand why a moving planet can transfer orbital energy during a gravity-assist manoeuvre.
For a classroom activity, students could plan a simplified journey between two locations on a diagram of the Solar System. Give them several possible routes and ask them to compare distance, travel time and the need for propulsion. They can then consider how passing near a moving planet might alter a spacecraft's trajectory. The diagram does not need to reproduce a real mission accurately to introduce the underlying problem-solving process.
Older students could extend the activity by investigating how mission designers use mathematical models and observations to predict a spacecraft's position. They could discuss why a small error in a trajectory can matter over a long journey and why spacecraft require careful tracking and course corrections.
Mariner 10 also offers a way to introduce Mercury. Because the planet orbits relatively close to the Sun, missions to Mercury face distinctive navigation and thermal challenges. Students can compare the scientific value of visiting a planet with the engineering demands of reaching it, helping them see that space exploration requires both scientific questions and practical solutions.
How to use science history as a classroom activity
The three events of 3 November can be used as short lesson starters, reading comprehension activities, discussion prompts or opportunities for students to practise scientific explanation. They are particularly effective when the historical story is followed by a question that requires students to apply what they have learned.
For example, students studying nuclear physics can compare different applications of fission. Those studying biology can evaluate the ethical questions raised by animal research. Students learning about forces and motion can investigate how gravity affects spacecraft trajectories. The same daily format can therefore support different topics without requiring every class to study the same branch of science.
A simple approach is to introduce the event, ask students to identify the central scientific concept, and then give them a question or task. Students might explain a process in their own words, draw a labelled diagram, compare two technologies or defend a conclusion using evidence. A brief written response at the end can help teachers see whether students have understood the connection between the historical event and the science.
For differentiation, upper elementary students could focus on describing what happened and identifying the relevant scientific field. Middle school students could explain the science using key vocabulary, while high school students could evaluate the evidence, consider ethical implications or apply mathematical ideas. These adaptations allow the same historical event to work across different age groups.
Science history can also support retrieval practice. Revisit a previous event later in the week and ask students to recall the key concept without looking at their notes. Over time, a short daily story can help students build a wider picture of how scientific knowledge develops and how different disciplines connect.
Looking ahead: More science history throughout November
There are plenty of other events to explore as the month continues. On 4 November, the first issue of the scientific journal Nature was published in 1869, offering a starting point for discussions about scientific communication and peer review. On 5 November, Edwin Armstrong presented frequency-modulation radio, providing a link to waves, sound and communication technology.
On 6 November, Tycho's supernova offers a way to discuss how careful astronomical observations challenged older ideas about the universe. On 7 November, Marie Curie's birthday connects to radioactivity, chemistry and physics. The following day, Wilhelm Röntgen's discovery of X-rays provides a link to electromagnetic radiation and medical imaging, while Edmond Halley's birthday gives astronomy students an opportunity to explore how repeated observations can reveal patterns and support predictions.
Later in the month, World Science Day for Peace and Development on 10 November encourages students to consider the role of science in society. The discovery of the fossil known as Lucy on 24 November offers a connection to human evolution and the interpretation of evidence. On 30 November, the birth of Ernst Chladni provides a route into sound and vibration through the patterns produced by vibrating surfaces.
These events span physics, biology, chemistry, mathematics, Earth science, astronomy, engineering and science communication. Teachers can select stories that match their current unit or use an unexpected event to introduce a new topic and invite students to generate questions.
Make science history part of your teaching routine
If you want to bring science history into lessons throughout the month without researching a new event every day, my November Science on This Day activity set includes 109 classroom-ready stories across 30 days of November. Each entry includes a concise summary, a classroom discussion question and a source link, giving teachers a straightforward starting point for a lesson, a short reading or a class conversation.
The set comes in four formats to suit different teaching situations: an interactive HTML version, slides with a class discussion question, a spreadsheet and a straightforward PDF. You can select individual events that fit your curriculum or use the calendar to establish a regular science-history routine.
You can also explore the The Teaching Astrophysicist store for more science resources, including free and paid activities across a range of topics and formats.
The events of 3 November show how science history can connect concepts that might otherwise be taught separately. Nuclear reactions lead to questions about energy and control, Laika's journey connects space exploration with biology and ethics, and Mariner 10 demonstrates how gravity and mathematics can help engineers explore another world. A short historical story followed by a thoughtful question can help students connect scientific knowledge with the decisions, challenges and people behind it.
Thanks for reading
Cheers and stay curious
Oliver - the Teaching Astrophysicist
