A dramatic, fresh impact crater dominates this image taken by the HiRISE camera on NASA's Mars Reconnaissance Orbiter on November 19, 2013.
  • NASA's Mars Reconnaissance Orbiter has taken nearly 7 million pictures of the red planet since leaving Earth 15 years ago. 
  • From dust storms to avalanches, the images reveal details of Mars' surface and weather patterns. 
  • Here are 12 of the most beautiful visuals the orbiter has captured so far. 
  • Visit Business Insider's homepage for more stories.

NASA's Mars Reconnaissance Orbiter left Earth on August 12, 2005 — almost exactly 15 years ago. The satellite began circling the red planet on March 10, 2006, and since then it has studied Martian temperatures, detected minerals on the planet's surface, and taken nearly 7 million images of our closest planetary neighbor.

The orbiter's main goal is to help scientists understand the role water has played on Mars throughout the planet's history, and the degree to which water still exists on the planet as liquid, vapor, or ice. 

In honour of the orbiter's 15th anniversary, here are some highlights from its massive portfolio of photos, and what each image reveals about Mars.

Mars is full of dust devils — millions form and die on the planet each day.
A towering dust devil casts a serpentine shadow over the Martian surface in this image from the HiRISE camera on NASA's Mars Reconnaissance Orbiter on February 16, 2012.

The dust devil in this photo snakes 185 miles above Mars' surface. Such dust devils hurl heat-trapping dust into the air, which impacts the planet's weather patterns.

A giant, once-in-a-decade dust storm swept over Mars in the summer of 2018. The dust clouded the solar panels of NASA's Opportunity rover, cutting off its power. Nobody has heard from the rover since June 10, 2018.
Side-by-side movies shows how dust enveloped Mars, thanks to the Mars Colour Imager (MARCI) camera on NASA's Mars Reconnaissance Orbiter.

Most dust storms on Mars occur on isolated sections of the planet. But every 10 years or so, regional storms combine into a huge one that covers the entire surface. 

The animated graphic above shows the planet in May 2018, before the dust storm began, then in June, when it hit full force. 

The orbiter captured the journey of the Opportunity rover, which was originally designed for a 90 day mission. The rover explored Mars for more than 14 years.
This final traverse map for NASA's Opportunity rover shows where the rover was located within Perseverance Valley the last date it made contact with its engineering team on June 10, 2018.

This illustrated image shows the entire 28-mile path of Opportunity, from its landing site in the Eagle Crater to Perseverance Valley, the site of its final transmission.

Mars' Curiosity rover, meanwhile, is still alive. The orbiter has watched Curiosity traverse the Gale Crater — it has traveled more than 14 miles since it landed in August 2012.
An animation shows the position of the Curiosity rover as it journeyed 1,106 feet (337 meters) through an area of Mount Sharp between May 31 and July 20, 2019.

This animated image shows the rover before and after it made a journey of 1,106 feet across Mount Sharp, a mountain within the Gale Crater.

Mars' surface is covered in giant ripples and dunes.
The High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter captured these sand ripples and large dune on February 9, 2009. Blue colour has been added to make textures easier to see.

This photo, taken by the orbiter's High Resolution Imaging Science Experiment (HiRISE) camera, captures huge, cresting waves of sand called megaripples, along with a large dune. 

Warmer weather brings giant avalanches to the red planet. The 2019 avalanche shown here plummeted down a 500m cliff.
The Hi-RISE camera aboard NASA's Mars Reconnaissance Orbiter captured this avalanche plunging down a 1,640-foot (500-meter) cliff on May 29, 2019.

In the Martian spring, warmer air vaporises ice chunks in Mars' North Pole, causing these giant avalanches. 

Known as brain terrain, this kind of pockmarked land on Mars remains a scientific mystery.
This surface texture of interconnected ridges and troughs is found throughout the mid-latitude regions of Mars.

Stretches of brain terrain can be found throughout mid-latitude regions of Mars. Some scientists think that these land areas sit on top of an icy core, so when chunks of underground ice vaporise, they cause sections of land above them to collapse. 

Dark sands streak across Mars' surface in its summer, then fade by winter. Scientists used to think flowing water caused these streaks, but most now believe they're caused by dark sand sliding down slopes.
This animated image series from the HiRISE camera on NASA's Mars Reconnaissance Orbiter show dark markings on a Martian slope changing with the seasons.

Some scientists think salty sand grains might pull water vapor from the atmosphere as it warms, causing those grains to darken and tumble downward. The phenomenon is known as recurrent slope lineae.

Large, pitted mounds on the red planet may contain methane.
Relatively bright mounds scattered throughout darker and diverse surfaces on Mars, May 15, 2018.

These large mounds contain craters at their center that resemble the collapsed centers of volcanoes on Earth. The pitted mounds may contain methane — a topic of interest for researchers, since it's not yet known whether Mars' methane comes from geologic events, microbial life, or both.

Because Mars' atmosphere is much thinner than Earth's, it doesn't burn up meteors as efficiently. So many large chunks of rock blast the planet's surface, creating large craters.
A dramatic, fresh impact crater dominates this image taken by the HiRISE camera on NASA's Mars Reconnaissance Orbiter on November 19, 2013.

The crater in this photo is roughly 100 feet wide, with a much larger blast zone around it.

The orbiter has also photographed Mars' two moons. The larger, Phobos, is just 13 miles across.
The HiRISE camera on NASA's Mars Reconnaissance Orbiter took two images of Phobos on March 23, 2008.

Scientists still don't know whether Phobos is an asteroid that entered the red planet's orbit or a chunk of Mars that broke off and became a moon millions of years ago.

Mars's other moon, Deimos, is even tinier than Phobos: It's only 9 miles across.

Occasionally, the orbiter's camera also turns back toward Earth.
This composite image of Earth and the moon as seen from Mars combines the best Earth image with the best moon image from four sets acquired by the HiRISE camera on NASA's Mars Reconnaissance Orbiter on November 20, 2016.

This composite photo was taken when Mars was about 127 million miles from Earth. Photo processors brightened the moon so to be visible next to our much brighter home planet. 

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