February 13, 2019

— Opportunity has reached its end.

One of NASA's two twin Mars Exploration Rovers that landed on the red planet in 2004, and the record holder for the longest off-Earth drive, Opportunity's mission was declared complete on Wednesday (Feb. 13), after 15 years on Mars' surface.

"I declare the Opportunity mission as complete," said Thomas Zurbuchen, NASA's associate administrator for science, speaking at a press conference held at the Jet Propulsion Laboratory (JPL) in Pasadena, California on Wednesday.

Opportunity ceased communicating with Earth on June 10, 2018, when a Mars-wide dust storm blanketed its location at "Perseverance Valley," a shallow channel incised from the rim's crest of Endeavour crater's floor. After sending more than a thousand commands in an attempt to restore contact, engineers in JPL's Space Flight Operations Facility made their last go at reviving Opportunity on Tuesday to no avail.

"Back in June, we were afflicted by a historic global dust storm on Mars, it just blackened the skies over the rover and starved the [solar-powered] rover for energy and the rover went silent," explained John Callas, the manager of the Mars Exploration Rover (MER) project at JPL. "We tried valiantly over these last eight months to recover the rover, to get some signal from it. We listened every single day."

"We needed a historic dust storm to finish this historic mission," added Abigail Fraeman, MER deputy project scientist at JPL.

Opportunity landed in the Meridiani Planum region of Mars on Jan. 24, 2004, seven months after its launch from Cape Canaveral in Florida. Designed to last just 90 Martian days (or sols) and travel 1,100 yards (1,000 meters), Opportunity vastly surpassed all expectations in its endurance, scientific value and longevity.

In addition to exceeding its life expectancy by 60 times, the rover traveled more than 28 miles (45 kilometers), more than any previous wheeled rover in history.

Opportunity completes Mars mission. Click to view video in a new, pop-up window. (NASA/JPL)

From the day Opportunity landed, a team of mission engineers, rover drivers and scientists collaborated to get the rover from one geologic site on Mars to the next. They plotted workable avenues over rugged terrain so that the 384-pound (174-kilogram), six-wheeled rover could maneuver around and, at times, over rocks and boulders, climb gravel-strewn slopes as steep as 32-degrees (an off-Earth record), probe crater floors, summit hills and traverse possible dry riverbeds.

All of Opportunity's moves were in service of its mission's primary objective: To seek out historical evidence of Mars' climate and water at sites where conditions may once have been favorable for life. Because liquid water is required for life (as we know it), Opportunity's discoveries implied that conditions at Meridiani Planum may have been habitable for some period of time in Mars' history.

"From the get-go, Opportunity delivered on our search for evidence regarding water," said Steve Squyres, principal investigator of the MER science payload at Cornell University in Ithaca, New York. "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."

Spirit, Opportunity's twin, landed 20 days earlier on Jan. 4, 2004, in Gusev Crater on the other side from Opportunity on Mars. Spirit logged almost 5 miles (8 kilometers) before it became stuck in a sand trap. Its mission ended in May 2011.

Over the course of its 15 years, Opportunity lost steering to one of its front wheels, a stuck heater threatened to severely limit the rover's available power, and it was almost immobilized by its own encounter with a sand trap. In 2015, Opportunity developed "amnesia," loosing use of its flash memory and, in 2017, it lost steering to its other front wheel.

Despite its impediments and in addition to its other feats, Opportunity set a one-day driving record on Mars, traveling 721 feet (220 meters) on March 20, 2005. It returned more than 217,000 images, including 15 360-degree color panoramas, and exposed the surfaces of 52 rocks to reveal fresh mineral surfaces for analysis. It also brushed off 72 more geological targets, preparing them to be inspected by spectrometers and a microscopic imager.

"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, the 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."