Mars is one of the planets in our solar system that humans know most about, and for good reason. The “Red Planet” has been lauded by scientists because of its similarity to Earth. The similarity convinces many that humans may be able to fashion a second home out of it. Especially considering near-apocalyptic warnings about the devastation of climate change, the idea of a possible escape plan seems tantalizing. And nothing has taught us more about Mars than visiting it ourselves … in the form of rovers.
Opportunity (nicknamed “Oppy”) launched July 07, 2003, and from the outset, it wasn’t expected to last long. The original mission length was just 90 Martian days, but the little rover has stayed alive for more than 15 years. NASA is expected to make a big announcement concerning the fate of the rover this Wednesday at 11 am. But first, let’s talk about what makes Mars so special.
The Red Planet
According to Universe Today, it’s impossible to know when Mars was “discovered.” People have observed it for over 4,000 years, since it is bright enough to be seen by the naked eye. You don’t need a telescope or even binoculars. In Roman mythology, it is the god of war, borrowed from the Greek god Ares. And ancient Mesopotamian texts refer to Mars as “the “star of judgment for the fate of the dead.”
However, Nicolaus Copernicus is credited with a wholesale shift in science in 1543. Because of his published findings, astronomers seriously considered that the Earth might not be the center of the solar system. And that was the beginning of discovering Mars as a planet.
Later down the line, Galileo Galilei was the first person to see Mars via telescope in 1610. Dutch astronomer Christiaan Huygens was first to draw a map of Mars that displayed terrain features in 1659.
He also observed light and dark spots on the surfaces of Mars and Jupiter, and thought it to be evidence of water and ice (we now know that he was very correct about that).
According to NASA, Opportunity scored a “hole-in-one” by landing in a crater where it found hematite, a mineral that usually forms in water. However, the water was acidic, and therefore made it more difficult for life to thrive.
Reddish Tint
Mars is known for its reddish tint, and according to Space.com, there’s a good reason for that:
“The simple explanation for the Red Planet’s color is that its regolith, or surface material, contains lots of iron oxide — the same compound that gives blood and rust their hue.”
However, the more complex answer is that during the formation of the planet, iron, a heavy element, would have naturally gravitated toward’s the planet’s core. But given Mars’s small size (and therefore weaker gravity) much of it would also stay up top, mixed with gas and dust. As it was exposed to oxygen, it would gain its famous reddish color. So if you wind the clock back a couple 4.5 billion years, you might see a more charcoal color.
Water
Water is the signature feature we look for in a potentially habitable planet is water. And no planet gives us hope for water like Mars.
PBS Nova explains that scientists used radar from orbital spacecraft to penetrate Mars’s polar ice caps with electromagnetic waves. These waves provide a reading, and every material reflects back with varying brightness. Knowing what water looks like on radar, scientists believe they found it underneath those ice caps — a mile beneath Mars’s surface. High salt content can keep the water liquid even at -90 degrees Fahrenheit, and NASA’s research suggests Mars once had more water than the Earth’s Arctic Ocean.
The presence of water is the linchpin in three main questions about Mars:
- Could we live there?
- Did something else live there?
- Does something else live there?
And questions like that are exactly what the Mars rovers were sent to the planet to explore.
The Little Rovers That Could
The Mars Exploration program began in 1993. The program was spearheaded by NASA with the intent to explore as much of Mars as possible. Specifically, the mission was the investigate Mars’ habitability. To accomplish this, they’ve used orbital spacecraft, landers, and of course, the lovable rovers.
How Opportunity survived this long is something of a mystery, with a combination of luck and engineering genius. Opportunity’s twin, Spirit, got caught in a sand trap in 2009 and couldn’t recharge its batteries, putting it out of commission. But Opportunity has traveled more than 28 miles in its time on Mars. However, scientists argue that the important thing is not how long it lasted, but what it did with its time.
In an oddly emotional Twitter thread, science reporter Jacob Margolis laid out the last moments of the rover’s life. The team had lost communication with Opportunity since June 2018, and hadn’t received word since. NASA says that since the loss of signal, over 835 recovery commands have been radiated to Opportunity.
The last message they received was basically, ‘My battery is low and it’s getting dark.’ — Jacob Margolis
In its life, Opportunity was responsible for taking more than 217,594 raw images of Mars. According to Margolis, it shares credit with all the rovers for expanding our understanding of water on Mars, and of environments that could be hospitable to life.
With Opportunity and Spirit gone, that leaves only Curiosity to explore the Red Planet. Launched in 2012, its design will serve as a basis for a planned Mars 2020 rover. However, it might be wiser to base your design on a rover that outperformed your expectations nearly 60 times over.
Cheers to Oppy, and may its mission lead to many more explorations of our vast cosmos.
Feature image provided via Jacob Margolis