A PLANET-HUNTING orbital telescope designed to detect worlds beyond our solar system has discovered two distant planets this week, five months after its launch from Cape Canaveral, Florida.

NASA’s Transiting Exoplanet Survey Satellite, made an early discovery of “super-Earth” and “hot Earth” planets in solar systems at least 49 light-years away, marking the satellite’s first discovery since its April launch.

TESS is on a two-year, $US337 million ($A463 million) mission to expand astronomers’ known catalogue of so-called exoplanets, worlds circling distant stars.

While the two planets are too hot to support life, TESS Deputy Science Director Sara Seager expects many more such discoveries.

“We will have to wait and see what else TESS discovers,” Seager said.

“We do know that planets are out there, littering the night sky, just waiting to be found.”

TESS is designed to build on the work of its predecessor, the Kepler space telescope, which discovered the bulk of some 3700 exoplanets documented during the past 20 years and is running out of fuel.

NASA expects to pinpoint thousands more previously unknown worlds, perhaps hundreds of them Earth-sized or “super-Earth” sized — no larger than twice as big as our home planet.

Those are believed the most likely to feature rocky surfaces or oceans and are thus considered the best candidates for life to evolve.

MIT researchers on Wednesday announced the discovery of Pi Mensae c, a “super- earth” planet 60 light-years away orbiting its sun every 6.3 days.

The discovery of LHS 3844 b, a “hot-earth” planet 49 light-years away that orbits its sun every 11 hours, was announced on Thursday.

The two newest planets, which still need to be reviewed by other researchers, offer the chance for follow-up study, officials said.

With four special cameras, TESS uses a detection method called transit photometry, which looks for periodic dips in the visible light of stars caused by planets passing, or transiting, in front of them.