Photos: Delta 4-Heavy launch gallery

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 fresh image from NASA’s New Horizons spacecraft released Tuesday showed the mission’s distant flyby target a billion miles beyond Pluto — nicknamed Ultima Thule — has an elongated shape like that of a peanut shell or a bowling pin, and the prospect of higher-resolution pictures arriving on Earth later in the day had scientists salivating for more.

In a triumph of deep space navigation and with Pluto shrinking in its wake, NASA’s New Horizons spacecraft has steered on a course to reach a tiny object named 2014 MU69 for a whirlwind visit on New Year’s Day 2019.