Summarize the following text. Scientists have always wondered if there is life anywhere out in the Space besides us. They have joined together on a major project called the Communication with Extra-Terrestrial Intelligence (CETI) which seeks to establish contact with any other living being in the universe. For this, they are beaming out radio signals into Space in the hope of attracting attention of "others worlds". It was thought that there is life on Mars. But two Viking Spacecrafts that landed on Mars in 1976 did not provide much evidence of life. The pictures sent by them showed Mars having a red sky instead of a blue one like ours and a pinkish coloured iron-rich soil. Its gravity is about half as strong as that of Earth so that the atmosphere is also much thinner than our planet. It has deserts, high mountains, volcanoes, craters, grooves like canals as well as summer and winter seasons. But there are no trees or signs of any life forms. However, a close inspection of a meteorite from Mars that fell on the Earth has revealed tiny fossils like bacteria 3.6 billion years old. This proves that some form of life existed there in the past. But who knows! Space probes have also been sent to planets Jupiter, Saturn, Uranus and Neptune. It will take years of a Space probe to reach a planet and many more years to analyze all the data sent to Earth by these probes.