﻿NASA's Curiosity Rover Finds Evidence of Ancient Civilization on Mars
Intro Over the last few decades,
NASA has been at the forefront of Mars exploration with one goal in mind, to search for signs of life
on the red planet and help us better understand all the factors that go into determining if
habitability is possible in the universe or if we humans are truly alone. The Curiosity rover has
arguably done more for the advancement of these studies than any other mission before it. Let's
take a look at this ingenious explorer and all the evidence of life it has found on Mars to date.
The Curiosity Rover The Curiosity rover was the
most ambitious Mars mission of its time flown by NASA. The rover landed on Mars in 2012 with
a primary mission to find out if Mars is, or was, suitable for life. Another objective is to learn
more about the Red Planet's environment. In March 2018, it celebrated 2,000 sols on the planet,
making its way from Gale Crater to Aeolis Mons, also referred to as Mount Sharp,
where it has looked at geological information embedded in the mountain's layers. Along the way,
it also has found extensive evidence of past water and geological change. One thing that makes
Curiosity stand out is its sheer size: Curiosity is about the size of a small SUV. It is 9 feet 10
inches long by 9 feet 1 inch wide and about 7 feet high. It weighs 2,000 lbs. Curiosity's wheels have
a 20-inch diameter that helps it traverse the rough Martian terrain. Engineers at NASA's Jet
Propulsion Laboratory designed the rover to roll over obstacles up to 25 inches high and to travel
about 660 feet per day. The rover's power comes from a multi-mission radioisotope thermoelectric
generator, which produces electricity from the heat of plutonium-238's radioactive decay.
The spacecraft launched from Cape Canaveral, Florida, on Nov. 26, 2011, and arrived on Mars
on Aug. 6, 2012, after a daring landing sequence that NASA dubbed "Seven Minutes of Terror."
Because of Curiosity's weight, NASA determined that the past method of using a rolling method
with land bags would probably not work. Instead, the rover went through an extremely complicated
sequence of maneuvers to land. From a fiery entry into the atmosphere, a supersonic parachute needed
to deploy to slow the spacecraft. NASA officials said the parachute would need to withstand
65,000 lbs. to break the spacecraft's fall to the surface. Despite these mammoth challenges,
the rover successfully touched down on Mars, starting a new era of interplanetary exploration.
The rover has a few tools to search for habitability. Among them is an experiment that
bombards the surface with neutrons, which would slow down if they encountered hydrogen atoms:
one of the elements of water. Curiosity's 7-foot arm can pick up samples from the
surface and cook them inside the rover, sniffing the gasses that come out of there and analyzing
them for clues as to how the rocks and soil formed. The Sample Analysis of Mars instrument,
if it does pick up evidence of organic material, can double-check that. On Curiosity's front,
under foil covers, are several ceramic blocks infused with artificial organic compounds.
Curiosity can drill into each of these blocks and place a sample into its oven to measure its
composition. Researchers will then see if organics appear that were not supposed to be in the block.
If so, scientists will likely determine these are organisms hitchhiking from Earth. High-resolution
cameras surrounding the rover take pictures as it moves, providing visual information that can
be compared to environments on Earth. Looking for Signs of Habitability
It didn’t take long for Curiosity to find what it went to Mars to look
for. Chemical analyses show that a grayish powder taken from the rover’s first drilled rock sample
contains clay minerals formed in water that was slightly salty, and neither too acidic
nor too alkaline for life. Previous missions to Mars have spotted clay minerals. And Curiosity
itself had already found signs that liquid water once flowed across the surface. But the
pinch of powder tested by Curiosity, from a rock nicknamed John Klein, is the first hard evidence
of water-borne clays in a benign pH environment. To date, it was the only definitive habitable
environment that was described and recorded on the Martian surface. X-ray analysis showed that
the ground-up rock comprised mostly igneous minerals such as feldspar, pyroxene, olivine,
and magnetite. But at least 20% of the rock was made up of clay minerals,
such as smectite, that form in the presence of water. The salts in the rock, such as halite,
are of the sort that life tolerates, unlike the iron salts found elsewhere on Mars by other
rovers which indicate an acidic environment. Besides hunting for habitability, Curiosity has
other instruments onboard that are designed to learn more about the environment surrounding it.
Among those goals is to have a continuous record of weather and radiation observations
to determine how suitable the site would be for an eventual human mission.
In December 2013, NASA determined the radiation levels measured by Curiosity
were manageable for a crewed Mars mission in the future. A mission with 180 days flying to Mars,
500 days on the surface, and 180 days heading back to Earth would create a
dose of 1.01 sieverts, this is within the acceptable range for a human body to endure.
A Decade of Sample Analysis Curiosity landed inside Mars' 96-mile-wide
Gale Crater on a mission to determine if the area could ever have supported microbial life.
The rover team soon determined that Gale's floor was a potentially habitable environment
billions of years ago, harboring a lake-and-stream system that likely persisted for millions of years
at a time. In a recent study, the research team looked at two dozen powdered rock samples
that Curiosity collected with its percussive drill from a variety of locations between August 2012
and July 2021. The rover fed this material into the SAM instrument to identify and characterize
carbon-containing molecules that are the building blocks of life on Earth. The scientists found that
nearly half of these samples were enriched in carbon-12, the lighter of the two stable carbon
isotopes, compared to previous measurements of Mars meteorites and the Martian atmosphere.
These high-carbon-12 samples came from five different locations within Gale Crater,
all of which featured ancient surfaces that had been preserved well over the eons.
On Earth, organisms preferentially use carbon-12 for their metabolic processes, so enrichment in
this isotope in ancient rock samples here is generally interpreted as a signal of biotic
chemistry. But carbon cycles on Mars aren't understood nearly well enough to make similar
assumptions for finding made on the red planet. The researchers came up with three possible
explanations for the intriguing carbon signal. The first involves Mars microbes producing methane,
which was then converted into more complex organic molecules after interacting with ultraviolet light
in the Red Planet air. These larger organics then fell back to the ground and were incorporated
into the rocks that Curiosity sampled. However, researchers state that similar reactions involving
UV light and non-biological carbon dioxide, by far the most abundant gas in Mars' atmosphere,
could have generated the result as well. It's also possible that the solar system drifted through a
giant molecular cloud rich in carbon-12 long ago. Lack of Data
For now, all three explanations fit the data at hand however researchers agree that more
data is needed to rule these explanations in or out. The new find is especially intriguing
because of the carbon-12 enrichment, but Curiosity has detected organic compounds on Mars before.
For example, the mission team previously reported the detection of organics in powdered
rock samples. The six-wheeled robot has also driven through plumes of methane, the simplest
organic molecule, on multiple occasions. It's unclear what's producing Mars' gaseous
methane or how old it is. For example, the compound may be
generated by microbes busily metabolizing beneath the frigid Martian surface today.
It could alternatively be produced by underground interactions of rock and hot water, with no life
involved. It could also be ancient material, produced either by organisms or abiotically,
that was trapped underground long ago and occasionally "burps" up onto the surface today.
The Curiosity team would love to drive through another methane plume and determine its carbon-12
content, exploring the origins of these organics further. But that would take a lot of luck,
given that researchers cannot predict when and where such plumes will appear. Further data from
NASA's newest rover Perseverance could also come in handy. The rover landed in a different crater
on the planet in February of 2021 and has been hard at work since. Perseverance is hunting for
signs of ancient Mars life and collecting dozens of samples that will be returned to Earth for
analysis, possibly as early as 2031. Outro
If you liked the video, please consider checking out this one which talks about
NASA's newest rover the Perseverance, and how it found signs of water on the Martian surface. Do
you think we should build a colony on Mars? Please share your thoughts in the comments section below.