Man has always been curious to explore the space. Exploration of space is the greatest adventure in the history of mankind. Space travel has been possible with the invention of satellites, probes, rockets, spacecrafts and space shuttles. Conditions in space are different to those on the earth. There is no atmosphere, no gravity and there is tremendous variation of temperature.

SATELLITES- Satellites orbit the earth like moon. They send information to the earth by radio signals. They produce photographs and make measurements, which help the meteorologists. Satellites help in weather forecasting, relay telephone, radio and television broadcasting. The information sent by satellite can be helpful for the scientists, army and for agriculture.

SPACE PROBES- They are the unmanned spacecraft. It carries cameras and other measuring equipments and send back pictures and other data back to the earth as radio signals. Pioneer 10 probe flew by Jupiter in 1973 and Mariner 10 probe visited Venus and Mercury in 1974. The Cassini-Huygens probe is orbiting around Saturn.

SPACECRAFT- It is a space vehicle and it can be used only once.

SPACE SHUTTLE- They can be reused many times. It cuts the cost of spaceflight by 90%. NASA explains space shuttle as a craft which could be “ launched like a rocket, houl like a truck and land like an aircraft”. It can carry satellites, spacecrafts into the orbit. The satellites can also be brought back to earth for repair.

• On October 4 1958, the first satellite was launched. It was called Sputnik. It orbited the earth for 92 days and then burned up as it entered the atmosphere.
• On July 20 1969, American astronaut Neil Armstrong became the first person to walk on the moon. As he stepped down from the space craft he said these words, “ That’s one small step for a man, one giant leap for mankind”.
• The first human being on space was Yuri Gagarin on April 12, 1961.
• Alan Shepard in American Freedom 7 spacecraft, made the next trip into space on May 5, 1961.
• The first space shuttle called THE ENTERPRISE was launched in April, 1981. There have been more than 70 missions since then.

The latest development in recent years is the setting up of space laboratories in the orbit around the earth. It is equipped with all kinds of instruments and apparatus foe scientific experiments. It is re-usable.

• The Russians launched the first laboratory in April 1971 and in 1984 the crew spent 8 months in space.
• The American Skylab was launched in May 1973. Three teams of astronauts visited it and the last team spent 84 days in it.
• On 28th November 1983, SPACELAB, a space laboratory was launched in the space shuttle. The scientists were than carried to conduct the experiments in the laboratory.