Photos: Delta 4-Heavy launch gallery

Data from the encounter of NASA’s New Horizons spacecraft with a frozen reddish snowman-shaped object a billion miles beyond Pluto last year suggest the building blocks of planets may have formed less violently than many scientists expected, officials said Thursday.

The New Horizons spacecraft has captured its last view of mysterious dark blotches strung across Pluto’s equator, and the spots will likely keep scientists guessing about their origin for decades to come.

A speedy space probe barreled past Pluto for a one-shot flyby Tuesday, becoming the first spacecraft to ever visit the frozen, reddish world at the solar system’s distant frontier.