2015 was a big year for space — living in it, travelling through it, and unraveling its many mysteries. Here are a few of the year's biggest advances and events, starting from our neck of the solar system and moving outward.
Going to space is no longer only possible for national organizations — commercial spaceflight is making great progress in getting off the ground. NASA has commissioned both Boeing and SpaceX to create crew capsules — which the companies call the Starliner and Dragon, respectively — and ongoing tests are proving the reliability of U.S.-built launch platforms like the Falcon 9.
That said, 2015 was notable not just for successes, but some highly visible failures. The tragic breakup of Virgin Galactic's SpaceShipTwo reminded the world that spaceflight is a difficult and high-risk endeavor — the company is still moving forward with its space tourism plans, but with a renewed caution. A SpaceX rocket carrying supplies and schoolkids' experiments to the International Space Station exploded at launch in June, and an attempt to land a SpaceX rocket on a drone ship at sea failed — somewhat expectedly, but still spectacularly.
Fortunately, SpaceX succeeded near the end of the year with a flawless orbital launch and automated return of the Falcon 9's first stage, which landed on target near its Cape Canaveral launch pad to the cheers of thousands. This came shortly after Jeff Bezos' private space company Blue Origin also made a successful rocket landing after going to the edge of space and back — a suborbital trip, as SpaceX founcer Elon Musk was quick to point out, but clearly still a feat worth celebrating.
Meanwhile, in theaters, "The Martian" thrilled moviegoers with its tale of interplanetary isolation. And as unlikely as the story seemed, there was actually a lot of solid science behind it. ("Star Wars: The Force Awakens"? Not so much, say laser experts and Neil Degrasse Tyson.)
Just don't try any of Mark Watney's life-preserving but highly explosive experiments at home.
The space station was busy during its 15th consecutive year of human residence. Cosmonaut Mikhail Korniyenko and America's Scott Kelly began a historic yearlong stay on the ISS in March, while longtime resident Samantha Cristoforetti set records for women (and coffee lovers) in space before returning to Earth.
New cameras mean views of both the Earth and the ISS's occupants come down to the planet in glorious 4K, making for even more compelling viewing than before. And greens and veggies grown on the station will contribute to both science and astronauts' healthy eating.
Astronauts weren't the only things coming down from orbit. A mysterious object known as WT1190F captured the world's attention as it made a fiery descent at 24,000 mph — and though conspiracy theories abounded, it was probably just space junk.
In the Solar System
A relatively rare cosmic coincidence made for a beautiful "supermoon lunar eclipse" and lent a vivid red color to the moon in September. If you missed it, you'll have a long wait: the next one is scheduled for 2033.
On the Red Planet in 2015, the Curiosity rover spent its 1,000th sol on Mars and reached a full marathon in distance traveled. But that's nothing compared with the news from NASA researchers that Mars may have salty liquid water flowing on it right now.
Between there and Jupiter lies the dwarf planet Ceres, which attracted attention this year with a handful of extremely bright spots on its surface that scientists struggled to explain — prompting the usual theories of alien cities. Recent research may disappoint them, though: The spots are probably just salt.
A few million miles farther out, the New Horizons probe completed its 9-year journey, making a successful rendezvous with Pluto and its moons and giving Earth its first views of these distant bodies. The resulting pictures — the best were only just arriving in December — have fascinated astronomers and ordinary folks alike. Pluto is a colorful, varied world, it turns out — and the data flowing in from the probe will keep scientists occupied for years.
No little green men or women were found this year, though there were hopes, as always. The mysterious dimming pattern of the KIC 8462852 system had the tinfoil hat crowd talking about alien-built "megastructures" interposing themselves between us and the star. The reality is probably a huge cloud of rocks like our own Oort cloud, which is very cool in its own right.
Meanwhile, in the deepest reaches of space, astronomers in 2015 spotted the most distant known galaxy (13 billion light-years away), the brightest known galaxy (300 trillion times brighter than our sun), and may have spotted some of the first stars ever to have been created.
Stay tuned in 2016 for more fascinating discoveries from the final frontier.