Uncrewed spacecraft

Uncrewed spacecraft, also called robotic spacecraft, are vehicles that travel through space without any people on board. They can be controlled from far away, follow instructions that are set before they launch, or make some decisions by themselves. These spacecraft are used for many missions that are too dangerous, far away, or expensive for humans to handle.

Some places in space, like the planet Venus or faraway worlds such as Saturn, Uranus, and Neptune, are too harsh or distant for humans to reach with today’s technology. Uncrewed spacecraft let scientists study these places safely.

The very first uncrewed mission was Sputnik, launched on October 4, 1957. It became the first human-made object to orbit Earth. Most satellites, landers, and rovers we use today are robotic. Even though many spacecraft meant for humans have robotic parts, true uncrewed spacecraft carry no people at all.

History

The first robotic spacecraft was launched by the Soviet Union in 1951. It carried two dogs on a short flight. The first artificial satellite, Sputnik 1, was launched by the USSR in 1957. It was followed by Sputnik 2, which carried a dog named Laika.

The United States launched its first satellite, Explorer 1, in 1958. This started a race between the US and the USSR to send better probes. These missions studied planets like Venus and Mars and learned more about the Moon. The first probe to reach space beyond our solar system, Voyager 1, was launched in 1977. It entered interstellar space in 2012, followed by Voyager 2 in 2018.

Design

In spacecraft design, the United States Air Force thinks of a vehicle as having two main parts: the payload and the bus. The bus is like the frame that holds everything together and gives the spacecraft power and control.

A spacecraft needs a strong structure to hold all its parts. It also needs systems to send and receive data, to know which way it is facing, and to talk with people on Earth. Spacecraft must be able to land safely, make their own power—often using solar cells—and shield themselves from very hot or cold temperatures and tiny space particles. To move around, spacecraft use rocket engines or other ways to push themselves forward.

Robotic vs. uncrewed spacecraft

Robotic spacecraft are built to work in tough places, and they can be very different from each other. An uncrewed spacecraft is any spacecraft that does not have people on board. It can work by itself or be controlled from Earth. Not all uncrewed spacecraft are robotic.

Robotic spacecraft send information and updates back to Earth using telemetry. Early spacecraft like Sputnik 1 and Explorer 1 did not get commands from Earth. Later, systems were added so people could control them from far away. As spacecraft travel farther from Earth, they need to make their own decisions. This is because it takes too long for signals to travel. Spacecraft like Cassini–Huygens and the Mars Exploration Rovers can work on their own for long times using their own computers.

Space probes

Main article: Space probe

Further information: List of Solar System probes

A space probe is a robotic spacecraft that explores space. These probes carry tools to study the Moon, planets, and faraway places. They send the information back to Earth for scientists. Some probes can collect samples and bring them back to Earth. To reach other planets, probes sometimes fly by the Sun or planets to travel faster.

Space telescopes

Main article: Space telescope

Further information: List of space telescopes

A space telescope or space observatory is a telescope that orbits Earth to study stars, planets, and other objects in space. Unlike telescopes on Earth, space telescopes are not affected by Earth’s atmosphere or light pollution. This gives them clearer and more detailed views. There are two main types of space telescopes. Some scan large areas of the sky. Others focus on specific objects or areas for closer study.

Cargo spacecraft

Further information: Comparison of space station cargo vehicles

Cargo or resupply spacecraft are robots that carry supplies like food, fuel, and tools to space stations where people live. They are different from space probes, which are used for science.

Automated cargo spacecraft have helped space stations since 1978. They have worked on stations like Salyut 6, Salyut 7, Mir, the International Space Station (ISS), and the Tiangong space station. Today, the ISS uses several types of cargo spacecraft, including the Japanese HTV-X, the Russian Progress, the American Cargo Dragon 2, and Cygnus. The European Automated Transfer Vehicle was used from 2008 to 2015. China’s Tiangong space station is supplied only by the Tianzhou.