This high-resolution image captured by NASA’s New Horizons spacecraft.
New Horizons flies by Pluto
NASA's New Horizons gave Pluto its first close-up. The spacecraft flew within 7,800 miles (12,550 kilometers) of Pluto's surface, capturing spectacular images of towering water-ice mountains and flowing fields of nitrogen glaciers, among other features.
New Horizons' observations showed that a large ice plain on Pluto harbors no discernible craters, indicating that the area has been resurfaced in the very recent past. This came as a big surprise to mission scientists, who have since been trying to figure out how tiny, icy Pluto managed to stay geologically active 4.5 billion years after its birth.
Water on Mars
Liquid water existing on the surface of Mars, in the here and now, has been the holy grail of Martian exploration for some time, but in October 2015 NASA announced that the orbiting Mars Reconnaissance Orbiter (MRO) had turned water-diviner to find compelling evidence that water is bursting out onto the red surface and trickling down the slopes of crater walls and hillsides.
Historic rocket landings
Spaceflight is an expensive proposition, in large part because rockets are used just once. But a sea change may soon be coming to the field.
On Nov. 23, the spaceflight company Blue Origin, successfully landed its New Shepard rocket after a brief flight to suborbital space. Then, on Dec. 21, SpaceX brought the first stage of its Falcon 9 rocket back for a soft touchdown during a mission that lofted 11 satellites to Earth orbit.
On March 6, NASA's Dawn spacecraft slipped into orbit around 590-mile-wide (950 km) Ceres, the largest object in the asteroid belt between Mars and Jupiter. In the process, Dawn became the first probe ever to visit a dwarf planet, as well as the first to orbit two different celestial bodies beyond the Earth-moon system. (Dawn circled the asteroid belt's second-largest denizen, Vesta, from July 2011 through September 2012.)
Dawn recently descended to its final and closest orbit, which takes the probe just 240 miles (385 km) from Ceres' heavily cratered surface.
ISS Astronauts -- A year living in space
In March 2015, NASA astronaut Scott Kelly and cosmonaut Mikhail Kornienko began the first-ever yearlong mission aboard the International Space Station, seeking to gauge just what this experience will do to their bodies and minds. (Crewmembers generally live in orbit for 5.5-month stints.)
They even have a control for some of this work — Scott's identical twin brother Mark, himself a former NASA astronaut, who remained on the ground. (Because Scott and Mark Kelly share the same set of genes.)
Second chance at Venus
Japan's Akatsuki probe was supposed to begin circling Venus on Dec. 6, 2010, but its main engine conked out during the crucial orbit-insertion burn, and the spacecraft went sailing off into deep space.
A second chance finally came on Dec. 6 of this year — exactly five years after the first opportunity. Akatsuki succeeded this time, using its small attitude-control thrusters to enter Venus orbit.
Rosetta goes around the sun
The European Space Agency's Rosetta spacecraft and its host comet, known as 67P/Churyumov-Gerasimenko, made their closest approach to the sun on Aug. 12, coming within 116 million miles (186 million km) of our star. spacecraft made its historic arrival at a comet in August 2014, and a year later, the probe and its icy companion zipped around the sun.
Rosetta, which also dropped a lander called Philae onto the comet's surface in November 2014, is now following 67P out into the depths of space. The spacecraft's mission will end in September 2016.
Curiosity celebrates 3 years on Mars
NASA's Curiosity rover celebrated an anniversary this past Aug. 5 — 3 years on Mars.
Curiosity is currently climbing through these foothills, reading the rocks for clues about Mars' shift from a relatively warm and wet world to the cold and dry place it is today.