The Brynhild Class Escort and Cobol Class Research Cruiser starships are capable of detecting native life on other planets. This ability is activated by the use of the Bio Scan mission. The range of the native life detection is the same as the sensor sweep range. These bio scanners are able to lock onto about 20% of all planets in range per turn. The planets that you own will not be scanned by the bioscanner.
The Robots have also developed an advanced bioscanner for use on a few of their starships.
The mission report will tell you the type and number of natives that are living on the planet scanned. It will also tell you the climate of a planet with native life. The report will not tell you which race, if any, owns the planet.
Twenty or more defense posts will shield a planet from bio scanners. The Evil Empire is able to cause bio scanners to return false readings to all races except the Rebels, but the reason for this exception is unknown.
See also: Out of Fuel.