Opportunity
After more than a decade since its landing on Mars, the long-serving exploration rover is still scouting the harsh alien terrain
Check out what the longserving rover is up to the surface of Mars
In 2003, NASA decided to capitalise upon a unique circumstance in the orbits of Earth and Mars by sending two rovers to the Mars in a mission called the Mars Exploration Rovers (MER) programme. The orbits of the two planets aligned in a way that only happens once every 26 months, and it meant the spacecraft could use less propulsive thrust to get the same mass to Mars than at any other circumstance. Spirit (MERA), the first rover sent to Mars, was launched on 10 June 2003, however, it ceased communication on 25 May 2011. The Opportunity rover (MER-B), launched on 7 July 2003, is still fully operational, and has travelled the furthest distance along the Red Planet’s surface than any other man-made rover.
Opportunity can also be thought of as a robotic geologist, as it is equipped with an array of adept instruments capable of probing the elusive Martian soil. This rover includes its equipment, six wheels and a set of solar panels that just won’t quit, and all of this is jampacked into a rover that is 1.5 x 2.3 x 1.6-metres (4.9 x 7.5 x 5.2-feet) in size. It was sent to examine and characterise the rocks and soils on Mars, and with much anticipation, it was hoped to unveil the previous presence of water.
The original mission was only planned for three months, which can also be referred to as Sol 90. A ‘Sol’ is a term used by astronomers for the duration of a solar day on Mars, as a Martian day is 40 minutes longer then an Earth day. The initial mission saw Opportunity land within the Eagle Crater at the Meridiani Planum and travel onward towards the Endurance Crater. Before it had even left the Eagle Crater, Opportunity took the time to analyse a layered rock outcrop nicknamed ‘El Capitan’.
This outcrop showed two minerals, hematite and jarosite, that are consistent with the presence of acidic water – Opportunity’s search for water had started well.
Opportunity has since journeyed onward through the Meridiani Planum, running countless geological tests on rocks and soils within many craters. But, after the initial surprise of signs of acidic water in the Eagle crater, the rover found definitive evidence for previous water presence hard to come by. In September 2006, Opportunity reached the Victoria Crater and found evidence for erosion on the bedrock that could have been from a liquid. The Mars Reconnaissance Orbiter’s Compact Reconnaissance Imaging Spectrometer for
Mars (CRISM) worked in partnership with Opportunity at one point in the mission, as the CRISM detected waterbearing minerals in the Santa Maria Crater. In December 2010, Opportunity reached the Santa Maria Crater to analyse further, but, unfortunately, it did not yield any groundbreaking discoveries.
Matthew Golombek, Opportunity’s project scientist based at NASA’s Jet Propulsion Laboratory (JPL), Pasadena, California, expressed what he thought about the rover’s greatest achievement: “Opportunity has documented water-rich environments on Mars. Both an early, ancient environment in which the water was neutral PH, and a subsequent one in which the water was acidic.” After having initially discovered the acidic region at the inception of its mission, Opportunity then arrived at the enormous Endeavour Crater after over seven years of travelling to discover more ancient, life-friendly waterbearing regions.
This came in December 2011, when Opportunity studied the rocks on the rim of the Endeavour Crater.
“Opportunity has documented waterrich environments on Mars”
Matthew Golombek
The unveiled bright veins of minerals known as gypsum were present, and this could only be deposited by water flowing through the underground fractures in the rocks. This discovery was described as a ‘slam-dunk story’ for the theory that water once flowed on the Red Planet.
The Endeavour Crater had more surprises in store – as the rover travelled along the rim it found more compelling signs for a more life-friendly, watery past on Mars. By analysing the clay minerals, Opportunity provided evidence for the idea that the clay minerals were formed in NEUTRAL-PH water.
Opportunity recently approached the fluid-carved valley known as the ‘Perseverance Valley’. Golombek said that the team were, "really jazzed at starting to see this area up close, and looking for clues to help us distinguish among multiple hypotheses about how the valley formed." Although Opportunity is showing clear signs of aging, it still has plenty of exploring left in the tank. This is a testament to the engineering and management by the team at NASA’s JPL, and this mission has provided – and continues to provide – us with vital data on a terrain we are becoming more and more familiar with.