M7G-677 is a planet in the Pegasus galaxy. Five hundred years before the Atlantis expedition reached Pegasus, an electromagnetic field generator, powered by a Zero Point Module, was constructed as a means of protection against the Wraith. Because it could only cover a small area of the planet, a suicide pact was made as a measure of population control. To prevent overpopulation, each individual would kill themselves at the age of twenty five. As such, the planet was inhabited almost exclusively by children, with only a few teens and some twenty year olds leading the planet. Over time, they came to forget about the original purpose of the pact, believing that they chose to die at this time because the Wraith would be uninterested in harvesting an immature 'crop'.
Major John Sheppard's team, while exploring the planet, discovered the truth about their protection, and Dr. Rodney McKay, having determined that the ZPM was too depleted to power Atlantis for more than a few hours, was able to expand the field without a significant power loss. Later, Dr. Radek Zelenka was sent to help repair the field, and appeared to have been accepted into the tribe. In 2008, the device had further troubles. (SGA: "Childhood's End", "Critical Mass", "Outcast")