All four planets are 20 percent to 50 percent larger than our own, suggesting a rocky surface, and orbit a red dwarf star called K2-72, which is 181 light years away from Earth in the Aquarius constellation. The two life-supporting contenders, K2-72c and K2-72e, appear to be in the "habitable zone" orbiting just far enough from their sun for liquid water to naturally exist, scientists said. The findings were among a report of 104 promising planets first announced in January but only recently published online.

While Kepler still spots exoplanets through a crude light meter, measuring the dip in brightness in distant stars when planets pass in front of them, the K2 mission reconfigured Kepler to spot dimmer stars like red dwarfs.

"An analogy would be to say that Kepler performed a demographic study, while the K2 mission focuses on the bright and nearby stars with different types of planets," said K2 study leader Ian Crossfield in a NASA blog post. "The K2 mission allows us to increase the number of small, red stars by a factor of 20, significantly increasing the number of astronomical 'movie stars' that make the best systems for further study."