A Farewell to “Oppy”…Maybe You Loved Us too

On February 12, NASA announced Mars rover Opportunity, which they haven’t been able to communicate for about eight months, officially dead. We wanted to remember the challenges overcome and the discoveries made that expanded our vision since 2004 by this robot lovingly nicknamed “Oppy”, on its long and successfully-finished mission.

About 6 months after their launch in 2003, Opportunity and its twin rover Spirit successfully landed at different points on the red planet 20 days apart in January 2004. Their main mission was to examine the rock and soil structures around their landing zones, to try and understand the water activity in Mars’s past, and to seek traces that can support the formation of life in the geological structure of this planet. The mission of these two rovers was planned to last for 90 days, with approximately 1000 meters to cover.

When Oppy stopped responding in June 2018, it was on the 5250th day of its mission and had travelled about 45 kilometres. But how did Opportunity achieve that? NASA engineers predicted that the dust on the surface of Mars would cover the solar panels of the rover within 3 months, rendering it inoperable. What they couldn’t estimate was that the reliably-periodical winds on the planet would clean these panels and help recharge the batteries. These seasonal winds helped with the mission and allowed Oppy to spend 14 winters on the Martian surface. Mars rovers’ batteries can be seen as technological masterpieces. Considered to be the best batteries in the solar system, Opportunity’s power supplies were still operating at 85% capacity after more than 5000 recharging cycles.

Oppy landed in a previously unknown crater in its planned landing site in Meridiani plains on January of 2004. This 22-meter radius impact crater was later given the name Eagle. The darkness here prevented Oppy to properly see around for 2 weeks. Even the first observations in its immediate surroundings revealed scientifically interesting rock formations.

In January 2004, Opportunity landed on a previously unknown 22-meter crater, which was later called Eagle (Eagle), in the planned landing site of Meridiani Planum. Because of the darkness in the crater, it took Oppy two weeks before he could properly see around. In the first investigations of the landing area, it viewed interesting rock formations. In the pictures sent by Oppy, scientists identified layers of sediment that were thought to be formed by the wind or, more importantly, by water. Closer investigation conducted with diamond-tipped abrasives on the Oppy’s robotic arm revealed cavities indicating the formation of hematite mineral and crystal. Later, the rounded hematite stones called “blueberries” and gypsum layers proved that the Martian history experienced an intensive surface water activity in a short time.

After hardly making it out of the Eagle crater, scientists decided that Oppy would land in the Endurance Crater. Rock and soil formations similar to the previous regions were investigated in this crater, which was tough to get in and out. The layers of clay viewed here constituted an important finding that increased the possibility of life in Mars since these could only form in non-acidic, neutral waters.

Opportunity crossed the Endurance crater, whose inclined reached up to 30 degrees, and provided NASA with invaluable experience not only with its geological findings, but also about the use of robotic vehicles on an alien planet. For example, in order to save a sand-struck Oppy in 2005, a series of experiments were carried out with on similar sand dunes on Earth. With this knowledge, NASA managed to rescue the Mars rover five weeks later.

Traveling from the Endurance crater to the area where his heat shield fell, Oppy made another very significant exploration here. An interesting stone was found in the immediate vicinity of the heat shield. Soon, this stone was identified as a meteorite. For the first time, a meteorite was found on an alien planet. During his 14-year research at Mars, Oppy would meet other meteorites containing rock and iron.

During its mission, Oppy broke the record of travelling on a different planet by covering a total of 45 kilometres, and broke another new ground by moving 220 meters in one day.

In 2007, while exploring the Victoria crater, the rover’s energy dropped down to critical levels due to a massive sandstorm. About a month later, when the atmosphere got clear, the panels were wiped clean and Oppy recharged to move on. It also found formations thought to be shaped by water in this crater.

Scientists then decided that Oppy would go to the Endeavour crater, which was 21 kilometres away, and the rover completed this journey in approximately three years. On the way, it examined many formations of scientific significance. When it reached his new destination in 2011, its twin, Spirit, was already disabled.

Another challenge Opportunity faced was a heater in its robot arm constantly remained open due to a malfunction. In order to prevent energy loss during heavy stormy weather and at night, the rover had to be turned off almost completely and turned on again every morning. In 2013 and 2014, NASA tried several ways to solve the issue in the flash memory that Oppy used to store information during the time it was turned off. When they failed, it was decided that the Mars rover should continue its mission with RAM. This brought the necessity of direct transmission of important data to the world before the device was shut down. The photographs it took from the Endeavour crater displayed the Siding Spring comet.

While viewing the Marathon valley from its way out of this crater, Oppy detected high amounts of silicon and aluminum in some stones. It was the first time such stones were recorded from Mars. Finally, while it was moving away from the Marathon valley, Oppy studied soil samples containing high sulfur content and magnesium sulfate, which could be related to the existence of water.

Due to the sandstorm, which began in May 2018 and took over the whole planet in a short time, Oppy remained in the dark and lost its energy up to a point where it became unable to communicate.

The high rate of dust in Martian storms prevents sunlight from reaching the planet surface. In order for the rover to charge, the atmosphere permeability level specified as “Tau” must be below 2.0. The surface value, which is around 0.5 Tau under normal conditions, was 10.8 Tau on June 10, 2018, the last day Oppy transmitted data.

Over the last eight months, NASA attempted to communicate with Opportunity more than 1000 times but failed. After endless efforts, they finally reported that Oppy’s mission, which exceeded the planned duration approximately 60 times, successfully ended.

Oppy provided us unique and unmatched knowledge on the geological past of Mars, its formation, and the possibility of finding water and life. It also provided information for future expeditions with rovers on other planets and gave us 217,594 photos and 15 panoramas with 360^o view.