Space exploration

“The sky calls to us. If we do not destroy ourselves, we will one day venture to the stars.” ― Carl Sagan
 

Space technology in everyday life

We do not always think about it, but our daily lives are heavily shaped by space technology, as modern society could barely function without it.

We encounter space technology all the time, both directly and indirectly. Have you checked the weather recently? Then you have probably seen a forecast built partly on measurements from weather satellites, which orbit Earth and monitor cloud formations, ocean currents, precipitation, and much more.

Services like Google Maps or Apple Maps use signals from navigation satellites, such as the American GPS satellites or the European Galileo satellites. If you have used your phone to navigate recently, satellites helped you on your way! Navigation satellites do not only help us find our way, they also help manage air and sea traffic around the world. So the next time you order something from abroad or travel yourself, satellites play a role almost every step of the way.

Furthermore, space technology plays a more indirect role in something as fundamental as the food on our table. Farmers around the world use satellite observations to monitor their fields, measuring temperature, soil moisture, and seasonal weather changes, helping them decide when to sow and when to harvest.

The principles of spaceflight

Have you ever wondered what drives a rocket, or what it means to be in orbit around Earth? The basic principles are actually quite simple, even if we tend to call it rocket science.

Rockets work because of a principle called Newton's third law. Isaac Newton was a scientist in the 1600s who described a set of laws governing how things move. His third law of motion is particularly important for rockets: it states that if an object pushes in one direction, an equal force arises in the opposite direction.

For a rocket, this means it must push something backward in order to move forward. You can compare it to the recoil of a firearm, or imagine standing on a skateboard and throwing a heavy bowling ball away from you. As the ball moves forward, you begin to roll backward. The same thing happens in a rocket: instead of bowling balls, it shoots enormous quantities of small particles out through its engine at extreme speed, pushing the entire rocket in the opposite direction.

From Chinese fireworks to Moon landings

Humans actually understood this principle long before Newton described it. As far back as ancient China around the year 1000, simple rockets made from bamboo tubes filled with gunpowder were already in use, primarily for warfare and fireworks. So next time you watch New Year's fireworks, you are looking at a technology with more than 1,000 years of history.

The next major step came during the Second World War with the German V-2 rocket, the largest rocket ever built at the time. Its purpose was to bomb London from long range, but it also marked something entirely new: for the first time, a rocket had enough range to leave Earth's atmosphere, making it the first human-made object to reach outer space. After the war, the two new superpowers, the USA and the Soviet Union, began developing ever larger rockets. An arms race was underway, but it quickly became clear that the competition was also about something else: space.

On 4 October 1957, the Soviet Union succeeded in placing an object in orbit around Earth: Sputnik 1, a simple metal sphere with four antennas and a radio transmitter, but the world's first satellite. The news came as an enormous shock to much of the Western world. The next step was sending humans into space. Again the Soviet Union got there first: on 12 April 1961, Yuri Gagarin completed one orbit of Earth and became the first human in space.

Shortly afterwards, the USA set an ambitious goal. President Kennedy announced that an American astronaut would walk on the Moon before the end of the decade. It happened in 1969 with Apollo 11, just months before the decade ended.

Being in orbit

The basic idea behind being in orbit is surprisingly simple: it is like falling around Earth.

Imagine standing on top of a very high mountain with a cannon loaded with as much gunpowder as you like (See illustration below). With a normal amount, the cannonball lands at the foot of the mountain. With more, it flies further toward the horizon. With even more, it might reach halfway around Earth. But if you fire it at around 8 kilometres per second, something special happens: the ball falls so fast sideways that Earth's surface curves away beneath it. It never hits the ground. It keeps going around the planet, and it is now in orbit.

This is exactly what satellites and space stations do, they are not hovering in place but constantly falling toward Earth, moving so fast horizontally that by the time they have fallen a little, Earth's surface has curved away beneath them by exactly the same amount. The International Space Station, for example, orbits at about 400 kilometres above Earth's surface and travels at roughly 28,000 kilometres per hour, completing a full orbit every 90 minutes. Astronauts aboard the station experience 16 sunrises and 16 sunsets every single day!

Space stations and space shuttles

In the years after the Moon landings, attention turned back toward Earth, and new technologies were developed for use in low orbit. Small space stations were built, and the USA developed the Space Shuttle as the first partly reusable spaceflight system. With it, astronauts could service satellites and even bring them back to Earth for repair, often far cheaper than building a new one.

In the Soviet Union, the modular space station Mir was developed, consisting of several modules docked together in space. After the Soviet Union's collapse, the USA and Russia began working more closely together. The Space Shuttle Atlantis visited Mir several times, and this collaboration eventually led to the construction of the International Space Station (ISS).

Russian modules originally designed for Mir-2 and American modules were assembled in a joint project, later joined by European and Japanese modules. More than 20 countries have contributed to the ISS. In its completed form, the station is roughly the size of a football pitch and is the largest human-made object in space, assembled through more than 40 rocket launches.

Researchers aboard the ISS conduct a wide range of experiments, both inside and on its exterior, many of which can only be carried out in weightlessness. Since November 2nd  2000, there have always been people aboard the station. If you were born after that date, you have never lived in a world where all humans were on Earth!

After the Space Shuttle retired in 2011, astronauts flew to the station using the Russian Soyuz capsule. Since 2020, it has also been possible to travel to the ISS using SpaceX's Dragon capsule, and China has had its own space station, Tiangong, since 2021, where Chinese astronauts, called taikonauts, conduct experiments on missions typically lasting around six months.

 Space Junk

The more we launch into space, the more we leave behind. Every rocket stage, defunct satellite, and fragment from a collision adds to a growing cloud of debris orbiting Earth at speeds of up to 7 kilometres per second. At that speed, even a tiny fleck of paint can cause serious damage to a spacecraft.

Today there are an estimated 1.2 million pieces of debris larger than 1 cm in orbit, and over 50,000 objects larger than 10 cm. The ISS performs collision avoidance manoeuvres multiple times a year, and in 2025 a Chinese crewed spacecraft had its window cracked by a debris impact. 

The greatest long-term concern is the Kessler Syndrome, a scenario where collisions between objects create more fragments, which cause more collisions, in a cascading chain reaction that could eventually make certain orbits completely unusable. Space agencies are now working on solutions, from guidelines requiring satellites to have end-of-life disposal plans, to active debris removal missions that will physically capture and deorbit junk for the first time. A healthy orbital environment is not just a scientific concern, it is essential for the satellites that our modern world depends on every day.

Reusable rockets

Over the past few decades, private companies have become an increasingly important part of spaceflight. SpaceX in particular has transformed the industry, now responsible for a large share of the world's rocket launches. A key part of their success is reusable rockets: their Falcon 9 rocket's first stage can land itself after launch and be flown again, making launches both faster and cheaper, inspiring other companies and countries to develop similar technology. SpaceX is also developing an even larger rocket called Starship, which is designed to be fully reusable, meaning both the upper and lower stages can be recovered and flown again. Starship is central to NASA's plans for returning to the Moon and is also being developed with Mars in mind as the eventual vehicle for crewed interplanetary travel.

The Moon and Mars

Several space programs have turned their attention back to the Moon in recent years. Artemis II launched on 1 April 2026, sending four astronauts on a 10-day journey around the Moon, the first crewed lunar mission since Apollo 17 in 1972. The next mission, Artemis IV, aims to land humans on the Moon's surface, currently targeted for around 2028. China is also working toward landing taikonauts on the Moon around 2029.

The goal of the Artemis programme is not just to visit the Moon again, but to build a lasting presence there, with a space station in lunar orbit and bases on the surface. This will help us learn to live further from Earth and prepare for the next great destination: Mars. You can read much more about the plans and challenges of sending humans to Mars in our section on Mission to Mars.