Yesterday, NASA issued a major public announcement that Fox News termed a “massive Mars discovery.”1 What was the discovery? At the announcement NASA spokesman and research scientist at NASA Goddard, Jennifer Eigenbrode, said, “We found organic molecules in rocks from an ancient lake bed.”2 Paul Mahaffy, director of the Solar System Exploration Division at NASA Goddard added, “Organic compounds are fundamental to our search for life.”3 Readers can watch a video recording of the NASA announcement here. Readers can access the peer-reviewed papers on the methane discovered by Curiosity here4 and here.5
When they hear the term “organics” most lay people think proteins, DNA, RNA, or cell membranes. Biochemists, however, define the term much more broadly. All hydrocarbon molecules are considered organic. What the NASA Mars rover Curiosity discovered was methane. Methane, as its chemical designation, CH4, denotes, consists of one carbon atom and four hydrogen atoms. Thus, methane ranks as one of the simplest “organic” molecules.
The word “discovery” also is a bit problematic. Curiosity has been detecting methane on Mars for the past 4.5 years. For the first time, however, Curiosity found methane in one of its core drills. For 18 months Curiosity’s core drill machinery had been out of commission. Once it was back in operation, NASA scientists had Curiosity drill into the mudstone layers of a 3.5-billion-year-old dry lake bed known as Gale Crater. It was in that core drill that Curiosity detected methane.
Likely Source of Martian Methane
NASA scientists see methane as a possible sign of life because there are bacteria (methanogens) on Earth that emit methane and other bacteria that consume methane (methanotrophs). NASA scientists speculate that methane on Mars could make possible the existence of methanotrophs or even that the methane on Mars comes from methanogens.
NASA scientists do recognize, nonetheless, that methane is far from an unambiguous signature of life. Yesterday’s NASA News release cited Jennifer Eigenbrode saying, “Curiosity has not determined the source of the organic molecules.”6
While most methane on Earth has as its source the decay of dead organisms or the dead parts of organisms or methane released by methanogens, geophysicists have known for decades that volcanic and geothermal active regions release methane from Earth’s interior magma. Another recently discovered source of abiotic (non-biological) methane on Earth are gas-water-rock chemical reactions at low temperatures.7
This latter source of abiotic methane is the most likely explanation for the methane detected in Curiosity’s core drill. Mars presently is volcanically and geothermally dormant. Mars is a low-temperature environment. Four billion years ago Mars was warm and wet. Its warm-wet environment was brief. At that time, Mars’s water reacted with carbon dioxide to make carbonates, a reaction that removed nearly all Mars’ carbon dioxide from its atmosphere. Lacking this greenhouse gas and the necessary plate tectonic activity to recycle the carbonates, Mars quickly and permanently became cold and dry. Some of Mars’ primordial water, however, remained as ice.
Except at the poles, Martian surface ice evaporates and escapes to outer space. (On present-day Mars the boiling point of water is the same temperature as the freezing point.) Below the surface of Mars, water ice is stable. Such water ice, when it is close to the surface, can melt and not immediately evaporate when the surface is warmed sufficiently by the Sun. This liquid water can participate in the gas-water-rock chemical reactions to explain the tiny amount of methane that Curiosity detected. The NASA press release stated that Curiosity’s findings were consistent with hydrocarbon concentrations on Mars “on the order of 10 parts per million or more.”8
That the methane detected by Curiosity likely comes from abiotic gas-water-chemical reactions is affirmed by the atmospheric methane Curiosity has been measuring over the past 4.5 years. This methane shows seasonal variations.9 The atmospheric methane concentration is consistently higher in the Martian summer than in the Martian winter. It is in the Martian summer when more subterranean water ice will melt and be available for gas-water-rock chemical reactions.
Coming Discovery of Life’s Remains on Mars
While I do not think the methane found in the Curiosity core drill is a sign of life or of life’s remains on Mars, I have been on public record since the 1980s that if NASA is sufficiently diligent they will find evidence for the remains of life on Mars. I am convinced such a discovery is inevitable because Earth has been so heavily bombarded in the past by meteoroids, asteroids, and comets that a calculated 200 kilograms of Earth soil resides on every 100 square kilometers of Mars’s surface. Two hundred kilograms of Earth soil contains, on average, about 20 quadrillion microbes. Therefore, the remains of Earth life reside everywhere on the Martian surface.
These remains of Earth life on Mars, however, have been subjected to long exposures of short wavelength ultraviolet solar radiation. Such radiation would have so broken down the remains of Earth life on Mars as to make the task of detecting those remains challenging, to say the least. Furthermore, 200 kilograms of Earth soil spread out over 100 square kilometers is an extremely thin layer. Nevertheless, I am convinced that if NASA is somehow able to fund missions of a few more tens of billions of dollars they will find the remains of Earth life on Mars.
Several years ago, I addressed scientists at NASA Space Center Houston. In my talk, I appealed to those scientists that it would be easier and much less expensive to find the remains of Earth life on the Moon than on Mars. The concentration of Earth soil on the Moon averages 20,000 kilograms per 100 square kilometers. Furthermore, the Moon is even more geologically dormant than Mars and calculations show that most of the Earth soil on Mars arrived via low-velocity impacts. Unlike Mars, there is a likelihood that the fossils of Earth’s first life may be found in pristine form. You can read more about finding the remains of life on the Moon in this article I wrote a few years ago.10
Earth’s geological activity has destroyed the fossils of Earth’s first life. I find it exciting that we may find the fossils of Earth’s first life on the Moon and discover who got the origin-of-life model correct—the atheists or the theists. As I reminded my audience at NASA Space Center Houston, atheists and theists make up 100 percent of the U.S. taxpayer base.
Curiosity’s Geophysical Mission
Curiosity, in my opinion, lacks the technology to prove or disprove the existence of life’s remains on Mars. However, I am not down on the Curiosity mission.
As Curiosity continues to probe the chemistry of Mars’s subterranean layers, scientists will learn a lot more about the geochemical and geophysical history of Mars. Such knowledge will not only deepen our understanding of Mars but of the Sun’s other rocky planets, including our planet Earth. Such understanding, I believe, will yield even more evidence for the exquisite fine-tuning design by the Creator that made possible our existence on Earth.