The 2010s saw the end of the missions of twin Mars rovers Spirit and Opportunity.

On Earth and in space, NASA had a busy decade in the 2010s.

In its human spaceflight program, the agency retired the space shuttle and is now close to launching humans to space again, this time on commercial crew vehicles. NASA also changed its long-term destination for humans a few times; currently the agency is targeting the moon and Mars.

Meanwhile, NASA robots flew through interstellar space, imaged thousands of planets and sent reams of scientific data back to researchers. Here are some of the agency's milestones over the last 10 years.

2010

The decade started with turmoil for NASA's human spaceflight program when President Barack Obama's administration canceled the plans from President W. George Bush's administration to bring astronauts to the moon under the Constellation program. (In 2009, a NASA advisory commission that had gathered to evaluate Constellation noted that the then-5-year-old program was over cost and behind schedule.)

Also in this year, the space shuttle program began its last full year of operations, focusing on large payloads such as the cupola, a large window for Earth observations. NASA requested one last extra shuttle flight, which was approved in 2011.

Meanwhile, the Deep Impact spacecraft flew by Comet Hartley, becoming the first spacecraft to visit two comets. The Spirit rover on Mars fell silent about six years past its initial 90-day expiration date. The scientists behind the orbital Mars Odyssey mission released a global map of the Red Planet based on eight years of data from the spacecraft, which is still operating today.

2011

The shuttle program made its final bow this year carrying cargo to the International Space Station. One of the last shuttle flights delivered a $2 billion astrophysics experiment called the Alpha Magnetic Spectrometer in May. (Astronauts have been conducting spacewalks in 2019 to repair that instrument, which studies dark matter.) Finally, in July, the space shuttle made its last flight, wrapping up 30 years of operations and 131 flights (including two fatal accidents, in 1986 and 2003).

From then on, NASA astronauts would fly to space aboard Russian Soyuz capsules; discussions about how many seats to buy, and how often, would dominate much of the 2010s. The Obama administration chose to retain the planned Orion spacecraft, originally envisioned for the now-defunct Constellation program, recruiting it for other planned deep-space missions, including to an asteroid around 2025 and Mars in the 2030s.

Meanwhile, because of the soaring cost and numerous launch delays of the James Webb Space Telescope, which was then slated to launch in 2018, NASA said that the instrument would need to pull money from other planned science missions. But the ongoing NASA/European Hubble Space Telescope mission discovered a previously unknown moon around Pluto, Kerberos. (When the same instrument found a second, Styx, in 2012, NASA personnel began to worry that these moons meant the New Horizons probe might run into unexpected debris during its flyby of the dwarf planet in 2015.)

NASA also braved the inner solar system, as the Messenger spacecraft successfully entered orbit around Mercury after a seven-year journey. In the other direction, the Juno spacecraft launched toward Jupiter on Aug. 5, 2011. In Earth orbit, NASA's Glory observatory failed to reach orbit during launch, in an issue eventually traced back to the instrument's aluminum manufacturer. NASA launched the National Polar-orbiting Operational Environmental Satellite System Preparatory Project (NPP) to examine Earth weather and climate.

2012

The International Space Station entered a new era of cargo support when SpaceX's Dragon spacecraft made the first private flight to the space station. NASA began construction on the massive Space Launch System rocket to bring astronauts across the solar system. (That craft's first flight, originally expected in 2017, was delayed until at least 2021.

NASA survived 7 minutes of terror when the Curiosity rover safely landed on Mars in August, stepping up the agency's search for habitability on the Red Planet; within weeks of landing, the spacecraft had found an ancient streambed and evidence that water had flowed in the craft's landing area. Meanwhile, the Dawn probe bid goodbye to the large asteroid Vesta in September 2012, after characterizing the object's iron core and finding large craters on its surface.

2013

At the space station, Italian astronaut Luca Parmitano (who will ring in the new year in space) nearly drowned during a spacewalk when a water leak in the cooling system filled his helmet with fluid. Parmitano made it safely back to the space station, and NASA soon redesigned spacewalk procedures to improve astronaut safety. NASA began to contemplate extending the space station's tenure beyond its believed expiration date of 2020.

At Mars, damaged wheels on the Curiosity rover forced NASA to seek smoother terrain. The NASA/European Solar and Heliospheric Observatory mission watched Comet ISON plunge into the sun over Thanksgiving, belying predictions that the comet could be one of the brightest in recent memory.

So many gyroscopes failed on the Kepler space telescope, by now long past its prime planet-hunting mission, that NASA pioneered a new technique that used the pressure of the sun to hold the instrument stable. This allowed Kepler to continue work under an extended mission, known as K2.

In other mission milestones, the Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft launched for the Red Planet on Nov. 18. Meanwhile, NASA announced an Asteroid Redirect Mission to snag a boulder off an asteroid in order to begin testing planetary defense techniques. And NASA launched a Landsat satellite, which continued an Earth-observation program that has been running since the early 1970s.

2014

In September, NASA selected Boeing and SpaceX for multi-billion-dollar contracts to eventually bring astronauts to the International Space Station. Originally, those flights were scheduled to launch by 2017, but programmatic and technical delays have pushed back the first crewed launch to at least 2020. NASA successfully tested the deep-space Orion spacecraft; at the time, the agency thought a second uncrewed launch would follow in 2017; that flight is now scheduled for no earlier than 2020.

NASA extended the space station's scheduled mission to 2024. NASA and Russia's Roscosmos space agency quibbled over their shared human spaceflight plans when a senior Russian official sarcastically suggested that NASA send astronauts to space by trampoline. However, the partnership continued with no delays to human spaceflight.

On Mars, the Curiosity rover arrived at its ultimate destination, Mount Sharp, about two Earth years after landing; critics at NASA had said that controllers were taking too long to reach the destination as the rover sampled other scientific sites en route. Curiosity also spotted its first signs of methane on the Red Planet; in the coming years, the rover found other possible signs of life, including oxygen and organic molecules.

Meanwhile, the NASA/European Cassini mission found signs of 101 water geysers at the Saturn moon Enceladus. Scientists studying the activity wondered whether the plumes could represent the sort of activity that might power microbial life. MAVEN arrived at the Red Planet to study the loss of Martian atmosphere over time.

2015

NASA astronaut Scott Kelly and Russian cosmonaut Mikhail Kornienko began a nearly yearlong mission in space, the first such long-duration flight since the Mir space station missions of the 1990s. Two cargo ships in a row failed to reach the space station, sparking speculation about how long a crew could survive without more supplies, but a third flight arrived as expected.

Two mission arrivals made headlines. The New Horizons spacecraft flew by Pluto in July and revealed a surprisingly complex world of ancient lakes and large mountains, prompting more cries from the astronomical community to give Pluto its planethood status back. The Dawn spacecraft arrived at dwarf planet Ceres in March for several years of investigation, including figuring out the nature of mysterious bright spots visible en route. These turned out to be salts.

Meanwhile, the long-running NASA and European Solar and Heliospheric Observatory discovered its 3,000th comet. The Messenger spacecraft impacted Mercury on April 30, wrapping up a four-year orbital mission that imaged the entire surface of that planet for the first time. NASA received approval to launch a mission to Jupiter's moon Europa, later called Europa Clipper, which is scheduled to launch early next decade.

2016

Astronauts began installing new docking ports for commercial crew vehicles to arrive at the International Space Station. Bigelow Aerospace launched an "inflatable room" to the space station for testing in April that was inflated in May and remains operational as of this writing. President Donald Trump was elected, and his first space priorities after assuming office in January 2017 included canceling the Obama administration's plans to send humans to visit an asteroid.

Meanwhile, on Mars, Curiosity's drill encountered problems that took about two years to address. NASA delayed the launch of the InSight mission to join Curiosity on the Red Planet after a seismometer vacuum leak forced engineers to pull the instrument for a fix. The agency toyed with the idea of canceling the mission, but a subsequent review identified InSight as a high priority for life-seeking missions, and it was rescheduled, launching in 2018.

The Juno spacecraft arrived at Jupiter on July 4, beginning its mission to study the atmosphere of the giant planet to gain more insight into the Jovian weather. NASA's Asteroid Redirect Mission passed a key design milestone.

2017

NASA astronaut Peggy Whitson captured the U.S. record for most overall time in space, landing in September with a total tally of 665 days in orbit.

Meanwhile, the NASA/European Cassini spacecraft wrapped up 13 years of investigations at Saturn by conducting a "grand finale" series of sweeps through the planet's rings. Then, controllers deliberately threw the machine into the atmosphere of the planet, to protect icy, potentially habitable moons in the neighborhood from any possibility of contamination.

Two missions faced hurdles: NASA delayed the James Webb Space Telescope launch from 2018 to 2019; that schedule has now slipped even further, to 2021. President Trump's new administration filed a budget request aiming to cancel the planned Asteroid Redirect Mission, which was officially canceled in 2018.

2018

The Trump administration released its first space policy directive in December, ordering NASA to fly astronauts to the moon in 2028. The plans rely on NASA's massive Space Launch System, which was the subject of a report on development and funding issues conducted by NASA's Office of Inspector General.

Two astronauts survived an aborted launch on a Soyuz rocket on Oct. 11. The International Space Station partners successfully adjusted the Expedition 58 launch date three weeks earlier to accommodate the missing crew rotation; a new launch went off without a hitch on Dec. 3.

Voyager 2, a spacecraft launched in 1977 to explore the outer planets, crossed out of the bubble surrounding our sun and into interstellar space, continuing to send back data about its environment.

Two venerable missions ended when they ran out of fuel: Dawn , which had been studying the dwarf planet Ceres, and the Kepler space telescope , which showed that exoplanets are common in our universe.

Three new missions joined the NASA roster. InSight finally launched to Mars in May and made a safe landing in November, accompanied by the first interplanetary cubesats. The Transiting Exoplanet Survey Satellite (TESS) launched to seek planets orbiting nearby, bright stars. The Parker Solar Probe launched in August to get the first close-up views of the sun.

2019

Preparations for NASA's commercial crew program entered the final stretches, with both SpaceX's Crew Dragon and Boeing's Starliner launching their first test flights. NASA's Office of Inspector General, however, warned that ongoing delays in the program are expected to lead to smaller space station crews for at least the first half of 2020.

NASA is also working to send astronauts safely back to the moon in 2024, after Vice President Mike Pence announced a four-year acceleration of the previous deadline. However, critics say the new timeline might not be realistic. NASA also celebrated the 50th anniversary of the Apollo 11 moon landing on July 20, marking the occasion with numerous events.

In space, astronauts began tricky repairs on a dark-matter detector called the Alpha Magnetic Spectrometer. NASA classified the missions as the most difficult spacewalk work since the Hubble Space Telescope upgrade conducted in 2009. NASA astronauts also performed the first all-woman spacewalk, and the agency announced that crewmember Christina Koch would stay in space three extra months, putting her on track to make the second longest spaceflight in NASA history.

NASA and other government agencies began the year during what would become the longest-ever government shutdown, prompting agency concerns about the long-term effects on astronomy.

Also in January, the New Horizons spacecraft flew by Kuiper Belt asteroid 2014 MU69, making that space rock the most distant object ever explored. The object is now formally known as Arrokoth. The New Horizons team began considering yet another, more distant destination to visit later in its mission.

Mars was particularly prominent in the agency's year. The Opportunity mission formally ended in February after the rover stopped responding to commands in 2018, following a dust storm. The InSight lander deployed its instruments on Mars; its seismometer has sent home intriguing results even as the lander's heat probe struggles to dig into the Martian surface. NASA's Mars Reconnaissance Orbiter marked 60,000 laps of the Red Planet; the orbiter's observations have helped with spacecraft landings and for observing change (such as new craters) on the Martian surface. And the agency continued launch preparations for its most advanced Mars rover yet, called Mars 2020, to search out habitable environments.

NASA prepared to say goodbye to the Spitzer Space Telescope, which finished its last year of operations of observing the universe in infrared light. Meanwhile, the NASA Lunar Reconnaissance Orbiter celebrated 10 years at the moon, which included numerous observations of water ice and old spacecraft landing or crash sites. The Chandra X-Ray Observatory marked its 20th anniversary of observing the universe in X-ray wavelengths.

And NASA looked ahead as well, as the ambitious Europa Clipper mission survived its latest funding challenge en route to a launch in the mid 2020s.

Follow Elizabeth Howell on Twitter @howellspace. Follow us on Twitter @Spacedotcom and on Facebook .