Exploring the Solar Connection to Earth's Water Origins
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Chapter 1: The Cosmic Origins of Earth's Water
Previously, I discussed how asteroids and comets played a pivotal role in delivering water to our planet around 4.5 billion years ago. Our planet, often referred to as the "blue planet," owes its water to space debris captured by Earth's gravitational pull during its formation. A recent article in The Conversation has expanded on this topic, suggesting a potential relationship between solar flares and the generation of water on the outer surfaces of asteroids. This implies that solar activity may continually refresh the water supply found within celestial bodies in our solar system.
The latest asteroid sampling conducted by JAXA (Japan Aerospace Exploration Agency) has yielded fresh insights into the origins of Earth's water. The primary conclusion drawn from these studies is that water is a prevalent element in the cosmic debris scattered throughout our solar system, indicating that it originated from asteroids and comets. Asteroids typically have a solid core comprised mainly of rocky materials and metals, whereas comets are largely composed of ice, dust, and some rocky substances.
Asteroids can be categorized into three distinct types: - C-type (chondrite): The most abundant asteroid type, made up of silica rock and carbonaceous materials. - S-type (stony): Comprised mainly of silicate materials and nickel-iron. - M-type (Metallic): Exclusively made of nickel-iron.
Even though the water found in asteroids closely resembles that of Earth, we encounter a dilemma: Earth’s water exhibits a lower deuterium to hydrogen (DH) ratio compared to most cosmic bodies. Many common water-rich C-type asteroids contain deuterium-enriched water, complicating the attribution of Earth’s water solely to these bodies. Moreover, cometary water tends to have a significantly higher DH ratio than that of Earth.
Section 1.1: Surprising Discoveries from the Itokawa Asteroid
One of the remarkable aspects of scientific research is its capacity to yield unexpected results. Recently, JAXA provided a group of researchers with access to three rare samples from the Itokawa asteroid, collected during the 2010 Hayabusa mission. The team aimed to explore the effects of space weathering on the asteroid's outer dust particles. Utilizing advanced technology, they employed a cutting-edge analytical technique known as atom probe tomography, which enables the examination of individual atoms and molecules, establishing their positions in a three-dimensional structure.
During their investigation, the researchers stumbled upon a surprising finding: a layer near the asteroid's surface rich in both hydroxide (OH) and water (H2O). This observation raised questions, as prior studies had suggested that this area should be "dry as a bone." The presence of water indicated that the asteroid was acquiring new hydrogen atoms from an external source. The sun, known to be the most substantial supplier of hydrogen in the solar system, appeared to be the answer.
Solar phenomena, such as coronal mass ejections, release bursts of protons and electrons traveling at speeds exceeding a million miles per hour. This process leads to the formation of solar winds. A hydrogen atom, the simplest atomic structure consisting of one proton and one electron, can be generated when some protons in solar winds capture an electron during their journey. NASA’s Imager for Magnetopause to Aurora Global Exploration (IMAP) spacecraft provided data confirming that roughly one in ten thousand protons in a solar wind collects an electron, thus forming hydrogen.
The first video discusses how some of Earth's water may have originated from the sun, exploring the implications of solar activity on our planet's water supply.
Section 1.2: The Formation Timeline of Earth's Oceans
The findings from the Itokawa asteroid analysis have led to a novel theory: water is continuously generated on the surfaces of asteroids due to the impacts of hydrogen-rich solar winds. Notably, these newly formed water molecules consist of light hydrogen, which may clarify why Earth’s water is lighter than expected if it were derived solely from asteroids. However, this theory does not specify when Earth's oceans formed.
Geological evidence, such as the Jack Hills zircons, suggests that liquid water existed approximately 100 million years after Earth's formation (around 4.4 billion years ago). Additionally, theoretical models of the early solar system indicate that water with varying DH ratios was present in the protoplanetary disc during the initial million years following the sun's formation. Therefore, water was accessible to Earth when it formed, and zircon studies indicate that standing water was present a century later. The closest we may come to determining when significant liquid water appeared on Earth is by identifying when the planet's surface temperature fell below the boiling point.
Regrettably, no temperature measurements were taken during that era. Geologists have labeled the first 500 million years of Earth's history as the Hadean Eon, believing it was "extremely hot" during this period. However, thermodynamic calculations suggest that Earth's crust may have solidified as early as ten million years post-formation. Essentially, it appears that water has been present on Earth since its inception, creating conditions conducive for life to emerge quickly on a planet abundant with water and favorably positioned to avoid extreme temperatures. All that remained was for life to miraculously come into existence.
The second video delves into the intriguing idea that there may be water on the sun, highlighting the unexpected sources of water in our solar system.