(CNN) It's time to say goodbye to Opportunity. The Mars rover's team made its last attempt to contact Opportunity on Tuesday night, and it went unanswered. On Wednesday, NASA confirmed that the mission is over.

The agency held a news conference to detail the results of recovery efforts since a dust storm encircled Mars last year.

"For more than a decade, Opportunity has been an icon in the field of planetary exploration, teaching us about Mars' ancient past as a wet, potentially habitable planet and revealing uncharted Martian landscapes," said Thomas Zurbuchen, associate administrator for NASA's Science Mission Directorate. "Whatever loss we feel now must be tempered with the knowledge that the legacy of Opportunity continues, both on the surface of Mars with the Curiosity rover and InSight lander and in the clean rooms of [NASA's Jet Propulsion Laboratory], where the upcoming Mars 2020 rover is taking shape."

NASA's Opportunity rover appears as a blip in the center of this square. This image taken by HiRISE, a high-resolution camera on board NASA's Mars Reconnaissance Orbiter, showed the dust storm over Perseverance Valley had substantially cleared.

NASA's Opportunity rover appears as a blip in the center of this square. This image taken by HiRISE, a high-resolution camera on board NASA's Mars Reconnaissance Orbiter, showed the dust storm over Perseverance Valley had substantially cleared.

These two views from NASA's Curiosity rover -- from June 7, left, and June 10 2018 -- show how dust increased over three days from a major Martian dust storm that became planet-encircling on June 20, 2018. Opportunity was stranded in the middle of the storm and wasn't heard from afterward.

These two views from NASA's Curiosity rover -- from June 7, left, and June 10 2018 -- show how dust increased over three days from a major Martian dust storm that became planet-encircling on June 20, 2018. Opportunity was stranded in the middle of the storm and wasn't heard from afterward.

The Mars Spirit rover was Opportunity's twin, and it's mission ended in 2011. Both rovers featured a piece of metal with the American flag on the side. They are made of aluminum recovered from the site of the World Trade Center towers in New York City.

The Mars Spirit rover was Opportunity's twin, and it's mission ended in 2011. Both rovers featured a piece of metal with the American flag on the side. They are made of aluminum recovered from the site of the World Trade Center towers in New York City.

In 2010, Opportunity took this panorama of the eastward horizon view of Endeavour Crater's rim.

In 2010, Opportunity took this panorama of the eastward horizon view of Endeavour Crater's rim.

These pointy features were called "Razorback." They're only a few centimeters tall, but the chunks of rock were found sticking up at the edge of flat rocks in Endurance Crater. They may have formed when fluids moved through rock fractures.

These pointy features were called "Razorback." They're only a few centimeters tall, but the chunks of rock were found sticking up at the edge of flat rocks in Endurance Crater. They may have formed when fluids moved through rock fractures.

Endurance Crater and its tendrils of sand presented a beautiful photo chance for the rover in 2004. Mars is full of dunes, and this is just one example Opportunity encountered.

Endurance Crater and its tendrils of sand presented a beautiful photo chance for the rover in 2004. Mars is full of dunes, and this is just one example Opportunity encountered.

This iron meteorite was the first meteorite of any type ever found on another planet. The basketball-sized meteorite is rich in iron and nickel, and Opportunity found it in 2005.

This iron meteorite was the first meteorite of any type ever found on another planet. The basketball-sized meteorite is rich in iron and nickel, and Opportunity found it in 2005.

Opportunity made an impact. A panoramic image shows the heat shield impact site when it landed in 2004.

Opportunity made an impact. A panoramic image shows the heat shield impact site when it landed in 2004.

A shadow selfie. On July 26, 2004, the rover took this photo commemorating its 90 days on Mars -- the amount of time the mission was supposed to last. Instead, it continued for 15 years.

A shadow selfie. On July 26, 2004, the rover took this photo commemorating its 90 days on Mars -- the amount of time the mission was supposed to last. Instead, it continued for 15 years.

Opportunity's panoramic camera took this photo of outcrop rocks that it encountered on its journey in 2005. Cracks and other features are obvious. The two holes visible were drilled by the rover to expose the underlying material.

Opportunity's panoramic camera took this photo of outcrop rocks that it encountered on its journey in 2005. Cracks and other features are obvious. The two holes visible were drilled by the rover to expose the underlying material.

The Mars Reconnaissance Orbiter took this photo of Victoria Crater, about a half-mile in diameter. It was Opportunity's home for 14 of the first 46 months it spent on Mars.

The Mars Reconnaissance Orbiter took this photo of Victoria Crater, about a half-mile in diameter. It was Opportunity's home for 14 of the first 46 months it spent on Mars.

Sometimes, when Opportunity's solar power was limited, it would stop between treks to different features on Mars. This 2010 photo of its tracks on the surface show it "hopping from lily pad to lily pad."

Sometimes, when Opportunity's solar power was limited, it would stop between treks to different features on Mars. This 2010 photo of its tracks on the surface show it "hopping from lily pad to lily pad."

The rover took a selfie to show how much dust it had accumulated in 2011 before the windy season helped knock some of it off.

The rover took a selfie to show how much dust it had accumulated in 2011 before the windy season helped knock some of it off.

Oppy's panoramic camera gathered this mosaic in 2014 of Wdowiak Ridge, as well as the rover's tracks to the right. This is about 70 degrees from north/northwest to east/northeast, showing the 500-feet ridge that rises 40 feet tall.

Oppy's panoramic camera gathered this mosaic in 2014 of Wdowiak Ridge, as well as the rover's tracks to the right. This is about 70 degrees from north/northwest to east/northeast, showing the 500-feet ridge that rises 40 feet tall.

More blueberries! Opportunity took this photo in 2004 of a rock called "Last Chance." The spherules embedded in the rock reminded the researchers of berries in muffins. The textures in the rock actually helped researchers determine that Mars had wet environmental conditions in the past.

More blueberries! Opportunity took this photo in 2004 of a rock called "Last Chance." The spherules embedded in the rock reminded the researchers of berries in muffins. The textures in the rock actually helped researchers determine that Mars had wet environmental conditions in the past.

Opportunity photographed its tracks in the soft sand between the Endurance and Victoria craters on the Meridiani Plains.

Opportunity photographed its tracks in the soft sand between the Endurance and Victoria craters on the Meridiani Plains.

While traversing on and around the ancient volcanic feature called Home Plate, Spirit took many images of finely layered and more frothy looking volcanic rocks.

While traversing on and around the ancient volcanic feature called Home Plate, Spirit took many images of finely layered and more frothy looking volcanic rocks.

From its perch high on a ridge, Opportunity recorded this image of a Martian dust devil twisting through the valley below. Just as on Earth, a dust devil is created by a rising, rotating column of hot air. When the column whirls fast enough, it picks up tiny grains of dust from the ground, making the vortex visible.

From its perch high on a ridge, Opportunity recorded this image of a Martian dust devil twisting through the valley below. Just as on Earth, a dust devil is created by a rising, rotating column of hot air. When the column whirls fast enough, it picks up tiny grains of dust from the ground, making the vortex visible.

Are those Martian blueberries? These tiny spherules pepper the sandy surface in this 3-centimeter (1.2-inch) square view of the Martian surface. Opportunity took this image while the target was shadowed by the rover's instrument arm.

Are those Martian blueberries? These tiny spherules pepper the sandy surface in this 3-centimeter (1.2-inch) square view of the Martian surface. Opportunity took this image while the target was shadowed by the rover's instrument arm.

This image is a cropped version of the last 360-degree panorama taken by the Opportunity rover's panoramic camera from May 13 through June 10, 2018. The view is presented in false color to make some differences between materials easier to see.

This image is a cropped version of the last 360-degree panorama taken by the Opportunity rover's panoramic camera from May 13 through June 10, 2018. The view is presented in false color to make some differences between materials easier to see.

Solar-powered Opportunity hasn't communicated with engineers since June 10. Dust has blocked out sunlight, and even the expected winds from November through January haven't helped clear Opportunity's sensors and panels. Engineers tried different things to revive Opportunity, sending repeated signals and commands to attempt to fix other potential issues. They've sent more than 835 recovery commands that remain unanswered.

"We have made every reasonable engineering effort to try to recover Opportunity and have determined that the likelihood of receiving a signal is far too low to continue recovery efforts," said John Callas, manager of the Mars Exploration Rover project at NASA's Jet Propulsion Laboratory.

The team is grateful for the long mission but sad to say goodbye. "Science is an emotional affair. It's a team sport, and that's what we're celebrating today," Zurbuchen said.

To the robot who turned 90 days into 15 years of exploration:



You were, and are, the Opportunity of a lifetime.



Rest well, rover. Your mission is complete.



(2004-2019)https://t.co/POzRmYauHo#ThanksOppy pic.twitter.com/oZLBc7XMJD — Spirit and Oppy (@MarsRovers) February 13, 2019

When Opportunity's twin, Spirit, became mired in soft soil in 2009 and its five working wheels couldn't free the rover, NASA held a "service" to commemorate the end of the mission in May 2011.

"Oppy," as the rover is affectionately known, has well outlasted her original 90-day mission. Instead, the rover has persisted for 15 years, sending back incredible data and photos from Mars to help uncover the Red Planet's secrets.

Opportunity and Spirit launched in 2003 and landed on Mars in 2004, searching for signs of ancient life.

Opportunity found hematite at its landing site: little round things all over the ground that looked like blueberries. These features form in water, a definitive sign to NASA that liquid water had been on the surface of Mars.

Opportunity was expected to travel 1,100 yards over 90 days on Mars. Instead, it traveled 28 miles.

It landed in Eagle Crater, moved on to Endurance Crater and planned to visit Victoria Crater. But the rover got stuck in the dunes of windblown material on the Martian surface. The engineers put it in reverse and "gunned it" to free the rover.

Opportunity was able to visit Victoria and spend two years driving around it and inside it before moving on to Endeavour Crater and ending in Perseverance Valley.

Opportunity's mission has led to many discoveries about the Red Planet, but perhaps the most exciting was when the rover found evidence that Mars once had water and supported conditions for sustaining microbial life.

"From the get-go, Opportunity delivered on our search for evidence regarding water," said Steve Squyres, principal investigator of the rovers' science payload at Cornell University. "And when you combine the discoveries of Opportunity and Spirit, they showed us that ancient Mars was a very different place from Mars today, which is a cold, dry, desolate world. But if you look to its ancient past, you find compelling evidence for liquid water below the surface and liquid water at the surface."

Photos: The best moments on Mars Photos: The best moments on Mars This artist's illustration shows the ExoMars Trace Gas Orbiter as it orbits Mars. The orbiter detected a layer of glowing green oxygen in Mars' atmosphere. Hide Caption 1 of 30 Photos: The best moments on Mars NASA's Curiosity Mars rover took a selfie shortly before completing its steepest climb yet on Mars up the Greenheugh Pediment, which tilted the rover 31 degrees. Hide Caption 2 of 30 Photos: The best moments on Mars NASA's Curiosity rover captured its highest-resolution panorama, including more than a thousand images and 1.8 billion pixels, of the Martian surface between November 24 and December 1, 2019. Hide Caption 3 of 30 Photos: The best moments on Mars The cloud in the center of the image is actually a dust tower that occurred in 2010 and was captured by the Mars Reconnaissance Orbiter. The blue and white clouds are water vapor. Hide Caption 4 of 30 Photos: The best moments on Mars This perspective of Mars' Valles Marineris hemisphere from July 9, 2013, is actually a mosaic comprising 102 Viking Orbiter images. At the center is the Valles Marineris canyon system, over 2,000 kilometers long and up to 8 kilometers deep. Hide Caption 5 of 30 Photos: The best moments on Mars NASA's Curiosity rover took this selfie on October 11, 2019, in the "Glen Etive" region. Hide Caption 6 of 30 Photos: The best moments on Mars The InSight lander was imaged from above by the Mars Reconnaissance Orbiter. Hide Caption 7 of 30 Photos: The best moments on Mars Is that cookies and cream on Mars? No, it's just polar dunes dusted with ice and sand. Hide Caption 8 of 30 Photos: The best moments on Mars The European Space Agency's Mars Express mission captured this image of the Korolev crater, more than 50 miles across and filled with water ice, near the north pole. Hide Caption 9 of 30 Photos: The best moments on Mars A recent photo taken by the Curiosity rover shows its current location, known as "Teal Ridge." The rover has been studying the clay-bearing unit in this region. Hide Caption 10 of 30 Photos: The best moments on Mars Cooled lava helped preserve a footprint of where dunes once moved across a southeastern region on Mars. But it also looks like the "Star Trek" symbol. Hide Caption 11 of 30 Photos: The best moments on Mars NASA's InSight lander used a camera on its robotic arm to capture this sunset on Mars on April 25. Hide Caption 12 of 30 Photos: The best moments on Mars InSight's seismometer recorded a "marsquake" for the first time on April 6, 2019. Hide Caption 13 of 30 Photos: The best moments on Mars A photo of a preserved river channel on Mars, taken by an orbiting satellite, with color overlaid to show different elevations. Blue is low and yellow is high. Hide Caption 14 of 30 Photos: The best moments on Mars This is NASA InSight's first selfie on Mars. It displays the lander's solar panels and deck. On top of the deck are its science instruments, weather sensor booms and UHF antenna. Hide Caption 15 of 30 Photos: The best moments on Mars Rovers can take selfies, too. This self-portrait of the Curiosity Mars rover shows the vehicle at the Quela drilling location in the Murray Buttes area on lower Mount Sharp. Hide Caption 16 of 30 Photos: The best moments on Mars Mars is far from a flat, barren landscape. Nili Patera is a region on Mars in which dunes and ripples are moving rapidly. HiRISE, onboard the Mars Reconnaissance Orbiter, continues to monitor this area every couple of months to see changes over seasonal and annual time scales. Hide Caption 17 of 30 Photos: The best moments on Mars What are blueberries doing on Mars? These small, mineral hematite-rich concretions are near Fram Crater, visited by NASA's Opportunity rover in April 2004. The area shown is 1.2 inches across. The view comes from the microscopic imager on Opportunity's robotic arm, with color information added from the rover's panoramic camera. These minerals suggests that Mars had a watery past. Hide Caption 18 of 30 Photos: The best moments on Mars Mars is known to have planet-encircling dust storms. These 2001 images from NASA's Mars Global Surveyor orbiter show a dramatic change in the planet's appearance when haze raised by dust-storm activity in the south became globally distributed. Hide Caption 19 of 30 Photos: The best moments on Mars Curiosity took images on September 9, 2015, of Mount Sharp, a hematite-rich ridge, a plain full of clay minerals to create a composite and rounded buttes high in sulfate minerals. The changing mineralogy in these layers of Mount Sharp suggests a changing environment in early Mars, though all involve exposure to water billions of years ago. Hide Caption 20 of 30 Photos: The best moments on Mars HiRISE captured layered deposits and a bright ice cap at the Martian north pole. Hide Caption 21 of 30 Photos: The best moments on Mars This image, combining data from two instruments aboard NASA's Mars Global Surveyor, depicts an orbital view of the north polar region of Mars. The ice-rich polar cap is 621 miles across, and the dark bands in are deep troughs. To the right of center, a large canyon, Chasma Boreale, almost bisects the ice cap. Chasma Boreale is about the length of the United States' famous Grand Canyon and up to 1.2 miles deep. Hide Caption 22 of 30 Photos: The best moments on Mars Although Mars isn't geologically active like Earth, surface features have been heavily shaped by wind. Wind-carved features such as these, called yardangs, are common on the Red Planet. On the sand, the wind forms ripples and small dunes. In Mars' thin atmosphere, light is not scattered much, so the shadows cast by the yardangs are sharp and dark. Hide Caption 23 of 30 Photos: The best moments on Mars From its perch high on a ridge, Opportunity recorded this image of a Martian dust devil twisting through the valley below. The view looks back at the rover's tracks leading up the north-facing slope of Knudsen Ridge, which forms part of the southern edge of Marathon Valley. Hide Caption 24 of 30 Photos: The best moments on Mars HiRISE took this image of a kilometer-size crater in the southern hemisphere of Mars in June 2014. The crater shows frost on all its south-facing slopes in late winter as Mars is heading into spring. Hide Caption 25 of 30 Photos: The best moments on Mars The Mars Reconnaissance Orbiter used its HiRISE camera to obtain this view of an area with unusual texture on the southern floor of Gale Crater. Hide Caption 26 of 30 Photos: The best moments on Mars A dramatic, fresh impact crater dominates this image taken by the HiRISE camera on November 19, 2013. The crater spans approximately 100 feet and is surrounded by a large, rayed blast zone. Because the terrain where the crater formed is dusty, the fresh crater appears blue in the enhanced color of the image, due to removal of the reddish dust in that area. Hide Caption 27 of 30 Photos: The best moments on Mars Opportunity used its panoramic camera to record this eastward horizon view on October 31, 2010. A portion of Endeavour Crater's eastern rim, nearly 19 miles in the distance, is visible over the Meridiani Planum. Hide Caption 28 of 30 Photos: The best moments on Mars In this artist's concept of NASA's InSight lander on Mars, layers of the planet's subsurface can be seen below and dust devils can be seen in the background. Hide Caption 29 of 30 Photos: The best moments on Mars The two largest quakes detected by NASA's InSight appear to have originated in a region of Mars called Cerberus Fossae. Scientists previously spotted signs of tectonic activity here, including landslides. This image was taken by the HiRISE camera on NASA's Mars Reconnaisance Orbiter. Hide Caption 30 of 30

Opportunity not only leaves behind a legacy of discovery, it became the longest-running rover and captured 217,594 raw images.

It will probably stay where it fell silent in Perseverance Valley. There, a historic global dust storm blackened the skies and starved its batteries of energy. The team listened for the rover every day, worrying as the skies continued to darken and the temperatures dropped. But the historic storm proved to be too much for Opportunity.

"I cannot think of a more appropriate place for Opportunity to endure on the surface of Mars than one called Perseverance Valley," said Michael Watkins, director of JPL. "The records, discoveries and sheer tenacity of this intrepid little rover is testament to the ingenuity, dedication and perseverance of the people who built and guided her."

This is the last image the panoramic camera captured before the rover communicated to engineers that its power was running low and that the dusty conditions were making things quite dark.

But Opportunity had shown other signs of age. It had a heater that was draining energy, and the clock was scrambled by loss of power, so it didn't know when to sleep. Then, the flash memory stopped, so the team had to recover the rover's data every day before it "forgot" what it saw.

Meanwhile, the Curiosity rover, which was unaffected by the storm, and the stationary InSight lander continue to study the Red Planet and carry on missions of discovery that were founded by Opportunity and Spirit.

Curiosity tweeted its farewell to Opportunity.

It seems to me you lived your life

like a rover in the wind

never fading with the sunset

when the dust set in.



Your tracks will always fall here,

among Mars' reddest hills;

your candle's burned out long before

your science ever will.#ThanksOppy. I owe you so much. pic.twitter.com/x0i5WqA9sL — Curiosity Rover (@MarsCuriosity) February 13, 2019

On Tuesday, InSight deployed its "mole," or heat flow probe, on the Martian surface, and in the coming weeks, it will be the first probe to go more than 16 feet below the surface. This will determine Mars' subsurface temperature and thermal conductivity.

InSight also shared a fond farewell to Opportunity on Twitter.

Celebrating the Opportunity rover -- a legendary explorer. I've just sent a message to the @MarsRovers and their team on completing their mission.



Send your own message: https://t.co/dljw3vBQYp

Read news: https://t.co/UQj8dMiqNJ pic.twitter.com/Bk4KEmdTaa — NASA InSight (@NASAInSight) February 13, 2019

On Wednesday, Opportunity's team bid her farewell while looking to the foundations the mission laid.

"When I think of Opportunity, I will recall that place on Mars where our intrepid rover far exceeded everyone's expectations," Callas said. "But what I suppose I'll cherish most is the impact Opportunity had on us here on Earth. It's the accomplished exploration and phenomenal discoveries. It's the generation of young scientists and engineers who became space explorers with this mission. It's the public that followed along with our every step. And it's the technical legacy of the Mars Exploration Rovers, which is carried aboard Curiosity and the upcoming Mars 2020 mission

"Farewell, Opportunity, and well done."

And one day, NASA hopes rover tracks will be alongside human footprints on the Red Planet.

"It is because of trailblazing missions such as Opportunity that there will come a day when our brave astronauts walk on the surface of Mars," NASA Administrator Jim Bridenstine said. "And when that day arrives, some portion of that first footprint will be owned by the men and women of Opportunity and a little rover that defied the odds and did so much in the name of exploration."