Exploring the planets

While manned spacecraft have ventured no further than Earth’s Moon, robotic craft have visited all the planets in the Solar System – and more than 100 moons.

Robotic spacecraft can visit places that would prove lethal for astronauts, such as the scalding surface of Venus or the deadly radiation belts around Jupiter. Packed with scientific instruments, telescopes, and cameras, that carry out dozens of experiments during their missions and capture thousands of images, which are sent back to Earth by radio.

Cassini – Hyugens spacecraft

Cassini – Hyugens is the largest spacecraft to visit another planet. It was launched in 1997 and arrived at Saturn in 2004.It had two parts: the Cassini orbiter, designed to orbit Saturn until 2017, and a probe called Hyugens, which touched down on Saturn’s large moon Titan. The main aim of the mission was to discover more about Titan – the only world in the Solar System other than Earth that has a dense, nitrogen – rich atmosphere.

Heat shield

Without a heat shield, the Hyugens probe would have burned up like a shooting star when it entered the atmosphere of Saturn’s moon Titan. The shield was made of silica fibre tiles able to withstand temperatures upto 1,500 degree Celsius.

Plasma spectrometer

This device measures charged particles trapped by Saturn’s powerful magnetic field.

Experiment platform

Huygens carried a range of scientific instruments of study conditions on Saturn’s moon Titan.

Large radio dish

The large radio dish communicate with Earth. It is also used to map Titan, which it does by bouncing radio waves off the surface.

Radio antennae

The three long antennae of the radio and plasma waves science instrument detect radio waves generated by Saturn’s outer atmosphere.

Small radio antennae

This is one of two small radio dishes that serve as backups in case the main dish breaks down.


An 11 metre boom carries instruments to measure Saturn’s magnetic field. The long boom reduces interference from other instruments on Cassini.


Cassini has four thrusters. These small engines adjust the craft’s flight path precisely.

Helium tank

Helium gas from this tank pushes fuel from the fuel tanks to the engine.

Fuel tanks

The fuel tanks carry two different liquids that burst into flame when mixed.

Cosmic dust analyser

This device measures the size and speed of cosmic dust particles in space.

Triple parachute

Packed under Huygens’s back cover were three parachutes that opened in turn to slow the lander’s descent on to Titan.Huygens discovered the world of freezing, orange – brown plains littered with pebbles of ice.

Path to the planets

The parts of spacecraft are often carefully planned to take them close to one or more planets on the way to their final destination. Using the pull of gravity of each world boosts their speed and saves fuel.Cassini – Huygens flow past Venus, Earth, and Jupiter on its way to Saturn.

Landmark missions

Since, the first spacecraft to visit a planet was launched in 1962, about 200 craft have explored the Solar System. Some of the most famous missions are shown here.

Venera 7

The first craft to touch down on another plan Venera 7 landed on Venus in 1970. It lasted 23 minutes before the searing heat destroyed it.

Lunokhod 1

Russian – built Lunokhod 1 was the first lunar rover. It landed on the Moon in 1970 and spent 322 days exploring, travelling a total of 10.5 km.

Voyager 1

Launched in 1977 and still operational, Voyager 1 is the furthest manmade object from Earth. It visited Jupiter in 1979 and Saturn in 1980.

Sojourner rover

The first rover to explore another planet was Sojourner. It reached Mars in 1997 and spent 12 weeka studying the soil and taking photos.


A Rover is a robotic vehicle built to explore the surface of a planet or moon. Four rovers have landed successfully on Mars. They receive radio commands from Earth but find their way around and carry out tasks independently.

Curiosity lands

The Curiosity rover was lowered on to Mars in 2012 by a rocket – powered craft.

References :

Knowledge Encyclopedia, DK Publications.

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