2016 has earned notoriety as a relentlessly unpredictable year marked by the passing of many beloved icons, including David Bowie and Muhammad Ali. The space community was not exempt from this trend; we were forced to bid farewell to several influential luminaries, including Apollo 14 astronaut Edgar Mitchell and Mercury Seven pioneer John Glenn.
But the past 12 months were also packed with astronomical discoveries and spaceflight victories, many of which will yield more exciting research in years to come. There's much to mourn, no doubt, but also plenty to celebrate in our roundup of the year's biggest stories from outer space, from the birth of a new field of astronomy to the death of a lonely comet orbiter.
10. Moon Express Cleared for a Lunar Landing
In August, the American spaceflight company Moon Express became the first private entity to receive permission to land on the Moon. Having secured this historic greenlight from the Federal Aviation Administration (FAA), the company is aiming to send a lander to the lunar surface sometime in 2017, with the long-term goal of extracting resources from the Moon and other celestial bodies. Off-Earth mining has been talked about for years, but in 2016, it took a major step towards reality.
9. The Return of the One Year Crew
On March 2, American astronaut Scott Kelly and Russian cosmonaut Mikhail Kornienko arrived safely back on Earth after 340 days on the International Space Station (ISS). Dubbed the One Year Crew, Kelly and Kornienko jointly broke the record for the longest single spaceflight on the ISS (though Mir cosmonaut Valeri Polyakov still holds the top spot on the all-time high score with 437 days). The yearlong mission included nearly 400 experiments geared towards understanding the effects of long duration spaceflight on the human body.
The success of the One Year Crew was not the only cause for celebration on the ISS. The station also received its first expandable module, the Bigelow Expandable Activity Module (BEAM), and astronaut Kate Rubins successfully sequenced DNA for the first time in space.
8. The Age of Reusable Rockets Is Nigh
For the majority of spaceflight history, rockets have been one-way vehicles. After delivering their payloads to orbit, boosters normally deorbit and burn up in the atmosphere.
Expendable launch systems are wasteful of time, money, and resources, not to mention they contribute to space debris. For private spaceflight companies SpaceX and Blue Origin, the answer is to build reusable rocket stages that can travel to space, then circle back to the launchpad for a new trip. Executing such a maneuver is a daunting task, but at the tail-end of 2015, both companies pulled off test landings of rocket stages for the first time. (Blue Origin is wants to corner the market on suborbital flights for tourists, while SpaceX is chasing the trickier goal of reusable orbital rockets).
If 2015 was the hallmark for demonstrating that rocket landings are possible, 2016 marks when they started to become commonplace, with SpaceX nailing several landings on floating drone ships (despite some explosive missteps here and there) and Blue Origin continuing to practice on land. Welcome to the era of round-trip rocketry.
7. Mars Fever
Human exploration of Mars has been speculated about for centuries, but it became a particularly hot topic in late September 2016, when Elon Musk outlined his plan for an Interplanetary Transport System that could ferry hundreds of passengers to and from Mars, and eventually, other locations in the solar system.
President Barack Obama shared Musk's optimism in a CNN op-ed on October 11, calling for America to take "the next giant leap" in spaceflight by sending humans to Mars by the 2030s. But though there is no lack of volunteers willing to journey to the Red Planet, it remains to be seen whether these new goals will actually materialize into crewed missions within that timeframe.
6. Juno, Meet Jupiter
After five years of interplanetary travel, NASA's Juno spacecraft finally arrived at Jupiter in the twilight hours of Independence Day, scooting itself into an elliptical polar orbit around the gas giant. In the months since, the orbiter has been busy calibrating its instruments and snapping gorgeous images, including the above shot of the planet's sunlit side. Juno is projected to study the enormous world until February 2018, when it will throw itself into Jupiter's gassy embrace and perish.
5. Pack Your Bags for Proxima b
We're lucky enough to live in an era when thousands of exoplanets (planets outside the solar system) have been catalogued. Still, the discovery of Proxima b, an Earth-scale world orbiting Proxima Centauri—the closest star to the Sun—was something special.
For starters, it's cool to know that there is a tantalizing planet around the same scale as Earth hanging out only 4.2 light years away, which is a stone's throw in cosmic terms. But the timing was also perfect, considering it came just a few months after celebrated physicist Stephen Hawking and billionaire entrepreneur Yuri Milner announced the Breakthrough Starshot initiative—a concept mission for traveling to the Alpha/Proxima Centauri system. Interstellar synergy at its finest.
4. Planet Nine (From Outer Space)
There has been much controversy over Pluto's official demotion as the solar system's ninth planet to a mere dwarf world of the Kuiper belt. But there's some kind of beautiful cosmic justice to the fact that astronomer Mike Brown, who led the charge to recategorize Pluto, has amassed compelling evidence that the solar system actually does have a ninth planet.
In January, Brown and his team published research that identified small objects in the outer solar system that are being gravitationally tugged by this hypothetical Neptune-sized planet with an orbit hundreds of times more distant than the one between Earth and the Sun. While astronomers haven't snagged a visual of this far-flung world yet, Brown expects it to be officially imaged in 2017. "I think that there'll be enough people looking for it that [...] somebody's actually going to track this down," he said in October, according to Space.com.
3. ExoMars Successes and Failures
The ExoMars 2016 spacecraft, a joint mission between the European Space Agency (ESA) and the Russian space agency Roscosmos, launched from Kazakhstan in March and arrived at Mars on October 19. Though the Trace Gas Orbiter successfully inserted itself into Mars orbit, the Schiaparelli landing module was destroyed after an explosive impact with the Martian surface, caused by a software glitch.
Naturally, it was a disappointing outcome for the ExoMars team, but mission leads have emphasized that the orbiter is the more important and expensive component, and it is operating perfectly.
2. RIP Rosetta
The Schiaparelli lander wasn't the only European spacecraft to fatally impact with its host world this year. The ESA Rosetta spacecraft, which had been orbiting comet 67P/Churyumov–Gerasimenko since November 2014, deliberately crashed into the comet's surface on September 30, ending its historic mission on a high note.
It was a heartfelt goodbye to one of Europe's most ambitious spaceflight endeavors, which succeeded in landing a probe on a comet for the first time. The finale was made all the more retrospectively bittersweet by the subsequent passing of Ukrainian astronomer Klim Churyumov, the co-discoverer of the comet and its partial namesake, on October 16. So farewell to Rosetta, and all who made the mission possible.
1. First Detection of Gravitational Waves
As evidenced by this roundup, 2016 was filled with juicy space stories. But despite all that competition, we reserved the top spot for the birth of an entire new field of science—gravitational-wave astronomy.
First predicted by Albert Einstein in 1916, gravitational waves are ripples in the fabric of spacetime, created by extreme cosmic events like the collision of black holes. Because these waves are extremely subtle, Einstein and many other experts doubted that human-made instruments would ever be precise enough to pick them up.
But on February 11, the visionaries of the Laser Interferometer Gravitational-Wave Observatory (LIGO) achieved this lofty and much-anticipated goal. Capable of detecting oscillations that are 1,000 times smaller than the width of a proton, LIGO picked up an ancient tremor created by two black holes that merged 1.3 billion years ago.
"This detection is the beginning of a new era," said Louisiana State University physicist Gabriela González, a LIGO collaborator, in a statement. "The field of gravitational wave astronomy is now a reality."
2016 was a ruthless year in a lot of ways, but the LIGO achievement—along with much of this roundup—shows it also had plenty of room left over for feats of wonder and curiosity. Here's to continuing with that spirit in 2017.
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