NASA has announced plans to launch a pair of missions to Venus between 2028 and 2030 – its first in decades – to study the atmosphere and geologic features of Earth’s so-called sister planet and better understand why the two emerged so differently.

The U.S. space agency said it was awarding about $500 million each to develop the two missions, dubbed DAVINCI+ (short for Deep Atmosphere Venus Investigation of Noble Gases, Chemistry and Imaging) and VERITAS (an acronym for Venus Emissivity, Radio Science, InSAR, Topography and Spectroscopy).

DAVINCI+ will measure the composition of the dense, hothouse atmosphere of Venus to further understand how it evolved, while VERITAS will map the planet’s surface from orbit to help determine its geologic history, NASA said.

DAVINCI+, consisting of a fly-by spacecraft and an atmospheric descent probe, is also expected to return the first high-resolution images of unique geological characteristics on Venus called “tesserae.” Scientists believe those features may be comparable to Earth’s continents and suggest that Venus has plate tectonics, according to NASA’s announcement.