Space investigation

The conditions in space are hostile to life and travelling in spacecraft is difficult and expensive. So scientists are using different methods to see if there is life on planets other than the Earth. Space probes can explore other planets without needing astronauts.

NASA Spirit robot on the surface of Mars.
NASA Spirit robot vehicle

Some of the missions undertaken by space probes include:

  • Viking 1 and Viking 2 - landed on Mars in the 1970s, took photographs and analysed soil samples
  • Mars Global Surveyor - went into orbit around Mars in 1996/1997 and mapped the surface in 3D
  • Spirit and Opportunity - two robot vehicles that landed on Mars in 2004

Life on other planets

The Earth's atmosphere contains about 21 per cent oxygen as a result of photosynthesis by plants and single-celled organisms. If we found evidence of oxygen in the atmosphere of another planet, it could indicate the presence of life forms. It is possible to detect oxygen and other gases on other planets by studying the light reflected from planets.

It is thought possible that alien civilisations, which are capable of transmitting radio signals, may exist. The Search for Extra-Terrestrial Intelligence (SETI) is a programme that uses radio telescopes to look for non-natural signals coming from space. It should be possible to even detect alien TV programmes, if they exist!

Space probes and landers are also looking for extra-terrestrial life. Space probes photograph planets, looking for evidence of life. We have photographs of channels on Mars that may have been created by flowing water. Landers touch down on planets and take a soil sample, which is analysed for evidence of life.