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Democritus, ancient Greek philosopher who is credited with the birth of atomic theory. Credit: phil-fak.uni-duesseldorf.de
As the philosopher Nietzsche famously said “He who would learn to fly one day must first learn to stand and walk and run and climb and dance; one cannot fly into flying.” This is certainly true when it comes to humanity’s understanding of the universe, something which has evolved over many thousands of years and been the subject of ongoing discovery.
And along the way, many names stand out as examples of people who achieved breakthroughs and helped lay the foundations of our modern understanding. One such person is Democritus, an ancient Greek philosopher who is viewed by many as being the “father of modern science”. This is due to his theory of universe that is made up of tiny “atoms”, which bears a striking resemblance to modern atomic theory.
Though he is typically viewed as one of Greece’s many pre-Socratic natural philosopher, many historians have argued that he is more rightly classified as a scientist, at least when compared to his contemporaries. There has also been significant controversy – particularly in Germany during the 19th century – over whether or not Democritus deserves credit for atomic theory.
This argument is based on the relationship Democritus had with contemporary philosopher Leucippus, who is renowned for sharing his theory about atoms with him. However, their theories came down to a different basis, a distinction that allows Democritus to be given credit for a theory that would go on to become a staple of the modern scientific tradition.
Democritus, by Hendrik ter Brugghen – Heraclitus, 1628. Credit: rijksmuseum.nl
Birth and Early Life:
The precise date and location of Democritus birth is the subject the debate. While most sources claim he was born in Abdera, located in the northern Greek province of Thrace, around 460 BCE. However, other sources claim he was born in Miletus, a coastal city of ancient Anatolia and modern-day Turkey, and that he was born in 490 BCE.
It has been said that Democritus’ father was from a noble family and so wealthy that he received the Persian king Xerxes on the latter’s march through Abdera during the Second Persian War (480–479 BC). It is further argued that as a reward for his service, the Persian monarch gave his father and other Abderites gifts, and left several Magi among them. Democritus was apparently instructed by these Magi in astronomy and theology.
After his father had died, Democritus used his inheritance to finance a series of travels to distant countries. Desiring to feed his thirst for knowledge, Democritus traveled extensively across the known world, traveling to Asia, Egypt and (according to some sources) venturing as far as India and Ethiopia. His writings include descriptions of the the cities of Babylon and Meroe (in modern-day Sudan).
Upon returning to his native land, he occupied himself with the study of natural philosophy. He also traveled throughout Greece to acquire a better knowledge of its cultures and learned from many of Greece’s famous philosophers. His wealth allowed him to purchase their writings, and he wrote of them in his own works. In time, he would become one of the most famous of the pre-Socratic philosophers.
The ruins of the ancient Greek city of Abdera, with the west gate shown. Credit: Wikipedia Commons/Marysas
Leucippus of Miletus had the greatest influence on him, becoming his mentor and sharing his theory of atomism with him. Democritus is also said to have known Anaxagoras, Hippocrates and even Socrates himself (though this remains unproven). During his time in Egypt, he learned from Egyptian mathematicians, and is said to have become acquainted with the Chaldean magi in Assyria.
In the tradition of the atomists, Democritus was a thoroughgoing materialists who viewed the world in terms of natural laws and causes. This differentiated him from other Greek philosophers like Plato and Aristotle, for whom philosophy was more teleological in nature – i.e. more concerned with the purpose of events rather than the causes, as well things like essence, the soul, and final causes.
According to the many descriptions and anecdotes about Democritus, he was known for his modesty, simplicity, and commitment to his studies. One story claims he blinded himself on purpose in order to be less distracted by worldly affairs (which is believed to be apocryphal). He was also known for his sense of humor and is commonly referred to as the “Laughing Philosopher” – for his capacity to laugh at human folly. To his fellow citizens, he was also known as “The Mocker”.
Scientific Contributions:
Democritus is renowned for being a pioneer of mathematics and geometry. He was among the first Greek philosophers to observe that a cone or pyramid has one-third the volume of a cylinder or prism with the same base and height. While none of his works on the subject survived the Middle Ages, his mathematical proofs are derived from other works with contain extensive citations to titles like On Numbers, On Geometrics, On Tangencies, On Mapping, and On Irrationals.
Right circular and oblique circular cones. Credit: Dominique Toussaint
Democritus is also known for having spent much of his life experimenting with and examining plants and minerals. Similar to his work in mathematics and geometry, citations from existing works are used to infer the existence of works on the subject. These include On the Nature of Man, the two-volume collection On Flesh, On Mind, On the Senses, On Flavors, On Colors, Causes concerned with Seeds and Plants and Fruits, and to the three-volume collection Causes concerned with Animals.
From his examination of nature, Democritus developed what could be considered some of the first anthropological theories. According to him, human beings lived short lives in archaic times, forced to forage like animals until fear of wild animals then drove them into communities. He theorized that such humans had no language, and only developed it through the need to articulate thoughts and ideas.
Through a process of trial and error, human beings developed not only verbal language, but also symbols with which to communicate (i.e. written language), clothing, fire, the domestication of animals, and agriculture. Each step in this process led to more discoveries, more complex behaviors, and the many things that came to characterize civilized society.
In terms of astronomy and cosmology, Democritus was a proponent of the spherical Earth hypothesis. He believed that in the original chaos from which the universe sprang, the universe was composed of nothing but tiny atoms that came together to form larger units (a theory which bears a striking resemblance to The Big Bang Theory and Nebular Theory). He also believed in the existence of many worlds, which were either in state of growth or decay.
In a similar vein, Democritus advanced a theory of void which challenged the paradoxes raised by his fellow Greek philosophers, Parmenides and Zeno – the founders of metaphysical logic. According to these men, movement cannot exist because such a thing requires there to be a void – which is nothing, and therefore cannot exist. And a void cannot be termed as such if it is in fact a definable, existing thing.
To this, Democritus and other atomists argued that since movement is an observable phenomena, there must be a void. This idea previewed Newton’s theory of absolute space, in which space exists independently of any observer or anything external to it. Einstein’s theory of relativity also provided a resolution to the paradoxes raised by Parmenides and Zeno, where he asserted that space itself is relative and cannot be separated from time.
Democritus’ thoughts on the nature of truth also previewed the development of the modern scientific method. According to Democritus, truth is difficult, because it can only be perceived through senses-impressions which are subjective. Because of this, Aristotle claimed in his Metaphysicsthat Democritus was of the opinion that “either there is no truth or to us at least it is not evident.”
However, as Diogenes Laertius quoted in his 3rd century CE tract, Lives and Opinions of Eminent Philosophers: “By convention hot, by convention cold, but in reality atoms and void, and also in reality we know nothing, since the truth is at bottom.”
Diogenes Laertius, Lives and Opinions of Eminent Philosophers, makes mention of Democritus and his theories. Credit: Public Domain
Ultimately, Democritus’ opinion on truth came down to a distinction between two kinds of knowledge – “legitimate” (or “genuine”) and bastard (or “secret”). The latter is concerned with perception through the senses, which is subjective by nature. This is due to the fact that our sense-perception are influence by the shape and nature of atoms as they flow out from the object in question and make an impression on our senses.
“Legitimate” knowledge, by contrast, is achieved through the intellect, where sense-data is elaborated through reasoning. In this way, one can get from “bastard” impressions to the point where things like connections, patterns and causality can be determined. This is consistent with the inductive reasoning method later elaborated by Renee Descartes, and is a prime example of why Democritus is considered to be an early scientific thinker.
Atomic Theory:
However, Democritus greatest contribution to modern science was arguably the atomic theory he elucidated. According to Democritus’ atomic theory, the universe and all matter obey the following principles:
Everything is composed of “atoms”, which are physically, but not geometrically, indivisible
Between atoms, there lies empty space
Atoms are indestructible
Atoms have always been, and always will be, in motion
There are an infinite number of atoms, and kinds of atoms, which differ in shape, and size.
He was not alone in proposing atomic theory, as both his mentor Leucippus and Epicurus are believed to have proposed the earliest views on the shapes and connectivity of atoms. Like Democritus, they believed that the solidity of a material corresponded to the shape of the atoms involved – i.e. iron atoms are hard, water atoms are smooth and slippery, fire atoms are light and sharp, and air atoms are light and whirling.
Democritus’ model of an atom was one of an inert solid that interacted mechanically with other atoms. Credit: .science.edu.sg
However, Democritus is credited with illustrating and popularizing the concept, and for his descriptions of atoms which survived classical antiquity to influence later philosophers. Using analogies from our sense experiences, Democritus gave a picture or an image of an atom that distinguished them from each other by their shape, size, and the arrangement of their parts.
In essence, this model was one of an inert solid that excluded other bodies from its volume, and which interacted with other atoms mechanically. As such, his model included physical links (i.e. hooks and eyes, balls and sockets) that explained how connections occurred between them. While this bears little resemblance to modern atomic theory (where atoms are not inert and interact electromagnetically), it is more closely aligned with that of modern science than any other theory of antiquity.
While there is no clear explanation as to how scholars of classical antiquity came to theorize the existence of atoms, the concept proved to be influential, being picked up by Roman philosopher Lucretius in the 1st century CE and again during the Scientific Revolution. In addition to being indispensable to modern molecular and atomic theory, it also provided an explanation as to why the concept of a void was necessary in nature.
If all matter was composed of tiny, indivisible atoms, then there must also be a great deal of open space between them. This reasoning has also gone on to inform out notions of cosmology and astronomy, where Einstein’s theory of special relativity was able to do away with the concept of a “luminiferous aether” in explaining the behavior of light.
Early atomic theory stated that different materials had differently shaped atoms. Credit: github.com
Diogenes Laertius summarized Democritus atomic theory as follows in Lives and Opinions of Eminent Philosophers:
“That atoms and the vacuum were the beginning of the universe; and that everything else existed only in opinion. That the worlds were infinite, created, and perishable. But that nothing was created out of nothing, and that nothing was destroyed so as to become nothing. That the atoms were infinite both in magnitude and number, and were borne about through the universe in endless revolutions. And that thus they produced all the combinations that exist; fire, water, air, and earth; for that all these things are only combinations of certain atoms; which combinations are incapable of being affected by external circumstances, and are unchangeable by reason of their solidity.”
Death and Legacy:
Democritus died at the age of ninety, which would place his death at around 370 BCE; though some writers disagree, with some claiming he lived to 104 or even 109. According to Marcus Aurelius’ book Meditations, Democritus was eaten by lice or vermin, although in the same passage he writes that “other lice killed Socrates”, implying that this was meant metaphorically. Since Socrates died at the hands of the Athenian government who condemned him, it is possible that Aurelius attributed Democritus death to human folly or politics.
While Democritus was highly esteemed amongst his contemporaries, there were also those who resented him. This included Plato who, according to some accounts, disliked him so much that he wished that all his books would be burned. However, Plato’s pupil Aristotle was familiar with the works of Democritus and mentioned him in both Metaphysics and Physics, where he described him as a “physicist” who did not concern himself with the ideals of form or essence.
Democritus meditating on the seat of the soul, by Léon-Alexandre Delhomme (1868). Credit: Pubic Domain
Ultimately, Democritus is credited as being one of the founders of the modern science because his methods and theories closely resemble those of modern astronomers and physicists. And while his version of the atomic model differs greatly from our modern conceptions, his work was of undoubted value, and was a step in an ongoing process that included such scientists as John Dalton, Neils Bohr and even Albert Einstein.
As always, science is an process of continuing discovery, where new breakthroughs are built upon the foundations of the old and every generations attempts to see a little farther by standing on the shoulders of those who came before.
The Earth's layers, showing the Inner and Outer Core, the Mantle, and Crust. Credit: discovermagazine.com
There is more to the Earth than what we can see on the surface. In fact, if you were able to hold the Earth in your hand and slice it in half, you’d see that it has multiple layers. But of course, the interior of our world continues to hold some mysteries for us. Even as we intrepidly explore other worlds and deploy satellites into orbit, the inner recesses of our planet remains off limit from us.
However, advances in seismology have allowed us to learn a great deal about the Earth and the many layers that make it up. Each layer has its own properties, composition, and characteristics that affects many of the key processes of our planet. They are, in order from the exterior to the interior – the crust, the mantle, the outer core, and the inner core. Let’s take a look at them and see what they have going on.
Modern Theory:
Like all terrestrial planets, the Earth’s interior is differentiated. This means that its internal structure consists of layers, arranged like the skin of an onion. Peel back one, and you find another, distinguished from the last by its chemical and geological properties, as well as vast differences in temperature and pressure.
Our modern, scientific understanding of the Earth’s interior structure is based on inferences made with the help of seismic monitoring. In essence, this involves measuring sound waves generated by earthquakes, and examining how passing through the different layers of the Earth causes them to slow down. The changes in seismic velocity cause refraction which is calculated (in accordance with Snell’s Law) to determine differences in density.
Model of a flat Earth, with the continents modeled in a disk-shape and Antarctica as an ice wall. Credit: Wikipedia Commons
These are used, along with measurements of the gravitational and magnetic fields of the Earth and experiments with crystalline solids that simulate pressures and temperatures in the Earth’s deep interior, to determine what Earth’s layers looks like. In addition, it is understood that the differences in temperature and pressure are due to leftover heat from the planet’s initial formation, the decay of radioactive elements, and the freezing of the inner core due to intense pressure.
History of Study:
Since ancient times, human beings have sought to understand the formation and composition of the Earth. The earliest known cases were unscientific in nature – taking the form of creation myths or religious fables involving the gods. However, between classical antiquity and the medieval period, several theories emerged about the origin of the Earth and its proper makeup.
Most of the ancient theories about Earth tended towards the “Flat-Earth” view of our planet’s physical form. This was the view in Mesopotamian culture, where the world was portrayed as a flat disk afloat in an ocean. To the Mayans, the world was flat, and at it corners, four jaguars (known as bacabs) held up the sky. The ancient Persians speculated that the Earth was a seven-layered ziggurat (or cosmic mountain), while the Chinese viewed it as a four-side cube.
By the 6th century BCE, Greek philosophers began to speculate that the Earth was in fact round, and by the 3rd century BCE, the idea of a spherical Earth began to become articulated as a scientific matter. During the same period, the development of a geological view of the Earth also began to emerge, with philosophers understanding that it consisted of minerals, metals, and that it was subject to a very slow process of change.
Illustration of Edmond Halley’s model of a Hallow Earth, one that was made up of concentric spheres. Credit: Wikipedia Commons/Rick Manning
However, it was not until the 16th and 17th centuries that a scientific understanding of planet Earth and its structure truly began to advance. In 1692, Edmond Halley (discoverer of Halley’s Comet) proposed what is now known as the “Hollow-Earth” theory. In a paper submitted to Philosophical Transactions of Royal Society of London, he put forth the idea of Earth consisting of a hollow shell about 800 km thick (~500 miles).
Between this and an inner sphere, he reasoned there was an air gap of the same distance. To avoid collision, he claimed that the inner sphere was held in place by the force of gravity. The model included two inner concentric shells around an innermost core, corresponding to the diameters of the planets Mercury, Venus, and Mars respectively.
Halley’s construct was a method of accounting for the values of the relative density of Earth and the Moon that had been given by Sir Isaac Newton, in his Philosophiæ Naturalis Principia Mathematica (1687) – which were later shown to be inaccurate. However, his work was instrumental to the development of geography and theories about the interior of the Earth during the 17th and 18th centuries.
Another important factor was the debate during the 17th and 18th centuries about the authenticity of the Bible and the Deluge myth. This propelled scientists and theologians to debate the true age of the Earth, and compelled the search for evidence that the Great Flood had in fact happened. Combined with fossil evidence, which was found within the layers of the Earth, a systematic basis for identifying and dating the Earth’s strata began to emerge.
The growing importance of mining in the 17th and 18th centuries, particularly for precious metals, led to further developments in geology and Earth sciences. Credit: minerals.usgs.gov
The development of modern mining techniques and growing attention to the importance of minerals and their natural distribution also helped to spur the development of modern geology. In 1774, German geologist Abraham Gottlob Werner published Von den äusserlichen Kennzeichen der Fossilien (On the External Characters of Minerals) which presented a detailed system for identifying specific minerals based on external characteristics.
In 1741, the National Museum of Natural History in France created the first teaching position designated specifically for geology. This was an important step in further promoting knowledge of geology as a science and in recognizing the value of widely disseminating such knowledge. And by 1751, with the publication of the Encyclopédieby Denis Diderot, the term “geology” became an accepted term.
By the 1770s, chemistry was starting to play a pivotal role in the theoretical foundation of geology, and theories began to emerge about how the Earth’s layers were formed. One popular idea had it that liquid inundation, like the Biblical Deluge, was responsible for creating all the geological strata. Those who accepted this theory became known popularly as the Diluvianists or Neptunists.
Another thesis slowly gained currency from the 1780s forward, which stated that instead of water, strata had been formed through heat (or fire). Those who followed this theory during the early 19th century referred to this view as Plutonism, which held that the Earth formed gradually through the solidification of molten masses at a slow rate. These theories together led to the conclusion that the Earth was immeasurably older than suggested by the Bible.
HMS Beagle in the Galapagos Islands, painted by John Chancellor. Credit: hmsbeagleproject.otg
In the early 19th century, the mining industry and Industrial Revolution stimulated the rapid development of the concept of the stratigraphic column – that rock formations were arranged according to their order of formation in time. Concurrently, geologists and natural scientists began to understand that the age of fossils could be determined geologically (i.e. that the deeper the layer they were found in was from the surface, the older they were).
During the imperial period of the 19th century, European scientists also had the opportunity to conduct research in distant lands. One such individual was Charles Darwin, who had been recruited by Captain FitzRoy of the HMS Beagle to study the coastal land of South America and give geological advice.
Darwin’s discovery of giant fossils during the voyage helped to establish his reputation as a geologist, and his theorizing about the causes of their extinction led to his theory of evolution by natural selection, published in On the Origin of Species in 1859.
During the 19th century, the governments of several countries including Canada, Australia, Great Britain and the United States began funding geological surveys that would produce geological maps of vast areas of the countries. Thought largely motivated by territorial ambitions and resource exploitation, they did benefit the study of geology.
The Earth’s Tectonic Plates. Credit: msnucleus.org
By this time, the scientific consensus established the age of the Earth in terms of millions of years, and the increase in funding and the development of improved methods and technology helped geology to move farther away from dogmatic notions of the Earth’s age and structure.
By the early 20th century, the development of radiometric dating (which is used to determine the age of minerals and rocks), provided the necessary the data to begin getting a sense of the Earth’s true age. By the turn of the century, geologists now believed the Earth to be 2 billion years old, which opened doors for theories of continental movement during this vast amount of time.
In 1912, Alfred Wegener proposed the theory of Continental Drift, which suggested that the continents were joined together at a certain time in the past and formed a single landmass known as Pangaea. In accordance with this theory, the shapes of continents and matching coastline geology between some continents indicated they were once attached together.
The super-continent Pangea during the Permian period (300 – 250 million years ago). Credit: NAU Geology/Ron Blakey
Research into the ocean floor also led directly to the theory of Plate Tectonics, which provided the mechanism for Continental Drift. Geophysical evidence suggested lateral motion of continents and that oceanic crust is younger than continental crust. This geophysical evidence also spurred the hypothesis of paleomagnetism, the record of the orientation of the Earth’s magnetic field recorded in magnetic minerals.
Then there was the development of seismology, the study of earthquakes and the propagation of elastic waves through the Earth or through other planet-like bodies, in the early 20th century. By measuring the time of travel of refracted and reflected seismic waves, scientists were able to gradually infer how the Earth was layered and what lay deeper at its core.
For example, in 1910, Harry Fielding Ried put forward the “elastic rebound theory”, based on his studies of the 1906 San Fransisco earthquake. This theory, which stated that earthquakes occur when accumulated energy is released along a fault line, was the first scientific explanation for why earthquakes happen, and remains the foundation for modern tectonic studies.
Earth viewed from the Moon by the Apollo 11 spacecraft. Credit: NASA
Then in 1926, English scientist Harold Jeffreys claimed that below the crust, the core of the Earth is liquid, based on his study of earthquake waves. And then in 1937, Danish seismologist Inge Lehmann went a step further and determined that within the earth’s liquid outer core, there is a solid inner core.
By the latter half of the 20th century, scientists developed a comprehensive theory of the Earth’s structure and dynamics had formed. As the century played out, perspectives shifted to a more integrative approach, where geology and Earth sciences began to include the study of the Earth’s internal structure, atmosphere, biosphere and hydrosphere into one.
This was assisted by the development of space flight, which allowed for Earth’s atmosphere to be studied in detail, as well as photographs taken of Earth from space. In 1972, the Landsat Program, a series of satellite missions jointly managed by NASA and the U.S. Geological Survey, began supplying satellite images that provided geologically detailed maps, and have been used to predict natural disasters and plate shifts.
Earth’s Layers:
The Earth can be divided into one of two ways – mechanically or chemically. Mechanically – or rheologically, meaning the study of liquid states – it can be divided into the lithosphere, asthenosphere, mesospheric mantle, outer core, and the inner core. But chemically, which is the more popular of the two, it can be divided into the crust, the mantle (which can be subdivided into the upper and lower mantle), and the core – which can also be subdivided into the outer core, and inner core.
The inner core is solid, the outer core is liquid, and the mantle is solid/plastic. This is due to the relative melting points of the different layers (nickel–iron core, silicate crust and mantle) and the increase in temperature and pressure as depth increases. At the surface, the nickel-iron alloys and silicates are cool enough to be solid. In the upper mantle, the silicates are generally solid but localized regions of melt exist, leading to limited viscosity.
In contrast, the lower mantle is under tremendous pressure and therefore has a lower viscosity than the upper mantle. The metallic nickel–iron outer core is liquid because of the high temperature. However, the intense pressure, which increases towards the inner core, dramatically changes the melting point of the nickel–iron, making it solid.
The differentiation between these layers is due to processes that took place during the early stages of Earth’s formation (ca. 4.5 billion years ago). At this time, melting would have caused denser substances to sink toward the center while less-dense materials would have migrated to the crust. The core is thus believed to largely be composed of iron, along with nickel and some lighter elements, whereas less dense elements migrated to the surface along with silicate rock.
Earth’s Crust:
The crust is the outermost layer of the planet, the cooled and hardened part of the Earth that ranges in depth from approximately 5-70 km (~3-44 miles). This layer makes up only 1% of the entire volume of the Earth, though it makes up the entire surface (the continents and the ocean floor).
The Earth’s layers (strata) shown to scale. Credit: pubs.usgs.gov
The thinner parts are the oceanic crust, which underlies the ocean basins at a depth of 5-10 km (~3-6 miles), while the thicker crust is the continental crust. Whereas the oceanic crust is composed of dense material such as iron magnesium silicate igneous rocks (like basalt), the continental crust is less dense and composed of sodium potassium aluminum silicate rocks, like granite.
The uppermost section of the mantle (see below), together with the crust, constitutes the lithosphere – an irregular layer with a maximum thickness of perhaps 200 km (120 mi). Many rocks now making up Earth’s crust formed less than 100 million (1×108) years ago. However, the oldest known mineral grains are 4.4 billion (4.4×109) years old, indicating that Earth has had a solid crust for at least that long.
Upper Mantle:
The mantle, which makes up about 84% of Earth’s volume, is predominantly solid, but behaves as a very viscous fluid in geological time. The upper mantle, which starts at the “Mohorovicic Discontinuity” (aka. the “Moho” – the base of the crust) extends from a depth of 7 to 35 km (4.3 to 21.7 mi) downwards to a depth of 410 km (250 mi). The uppermost mantle and the overlying crust form the lithosphere, which is relatively rigid at the top but becomes noticeably more plastic beneath.
Compared to other strata, much is known about the upper mantle, thanks to seismic studies and direct investigations using mineralogical and geological surveys. Movement in the mantle (i.e. convection) is expressed at the surface through the motions of tectonic plates. Driven by heat from deeper in the interior, this process is responsible for Continental Drift, earthquakes, the formation of mountain chains, and a number of other geological processes.
Computer simulation of the Earth’s field in a period of normal polarity between reversals. Credit: science.nasa.govThe mantle is also chemically distinct from the crust, in addition to being different in terms of rock types and seismic characteristics. This is due in large part to the fact that the crust is made up of solidified products derived from the mantle, where the mantle material is partially melted and viscous. This causes incompatible elements to separate from the mantle, with less dense material floating upward and solidifying at the surface.
The crystallized melt products near the surface, upon which we live, are typically known to have a lower magnesium to iron ratio and a higher proportion of silicon and aluminum. These changes in mineralogy may influence mantle convection, as they result in density changes and as they may absorb or release latent heat as well.
In the upper mantle, temperatures range between 500 to 900 °C (932 to 1,652 °F). Between the upper and lower mantle, there is also what is known as the transition zone, which ranges in depth from 410-660 km (250-410 miles).
Lower Mantle:
The lower mantle lies between 660-2,891 km (410-1,796 miles) in depth. Temperatures in this region of the planet can reach over 4,000 °C (7,230 °F) at the boundary with the core, vastly exceeding the melting points of mantle rocks. However, due to the enormous pressure exerted on the mantle, viscosity and melting are very limited compared to the upper mantle. Very little is known about the lower mantle apart from that it appears to be relatively seismically homogeneous.
The internal structure of Earth. Credit: Wikipedia Commons/Kelvinsong
Outer Core:
The outer core, which has been confirmed to be liquid (based on seismic investigations), is 2300 km thick, extending to a radius of ~3,400 km. In this region, the density is estimated to be much higher than the mantle or crust, ranging between 9,900 and 12,200 kg/m3. The outer core is believed to be composed of 80% iron, along with nickel and some other lighter elements.
Denser elements, like lead and uranium, are either too rare to be significant or tend to bind to lighter elements and thus remain in the crust. The outer core is not under enough pressure to be solid, so it is liquid even though it has a composition similar to that of the inner core. The temperature of the outer core ranges from 4,300 K (4,030 °C; 7,280 °F) in the outer regions to 6,000 K (5,730 °C; 10,340 °F) closest to the inner core.
Because of its high temperature, the outer core exists in a low viscosity fluid-state that undergoes turbulent convection and rotates faster than the rest of the planet. This causes eddy currents to form in the fluid core, which in turn creates a dynamo effect that is believed to influence Earth’s magnetic field. The average magnetic field strength in Earth’s outer core is estimated to be 25 Gauss (2.5 mT), which is 50 times the strength of the magnetic field measured on Earth’s surface.
Inner Core:
Like the outer core, the inner core is composed primarily of iron and nickel and has a radius of ~1,220 km. Density in the core ranges between 12,600-13,000 kg/m³, which suggests that there must also be a great deal of heavy elements there as well – such as gold, platinum, palladium, silver and tungsten.
Artist’s illustration of Earth’s core, inner core, and inner-inner core. Credit: Huff Post Science
The temperature of the inner core is estimated to be about 5,700 K (~5,400 °C; 9,800 °F). The only reason why iron and other heavy metals can be solid at such high temperatures is because their melting temperatures dramatically increase at the pressures present there, which ranges from about 330 to 360 gigapascals.
Because the inner core is not rigidly connected to the Earth’s solid mantle, the possibility that it rotates slightly faster or slower than the rest of Earth has long been considered. By observing changes in seismic waves as they passed through the core over the course of many decades, scientists estimate that the inner core rotates at a rate of one degree faster than the surface. More recent geophysical estimates place the rate of rotation between 0.3 to 0.5 degrees per year relative to the surface.
Recent discoveries also suggest that the solid inner core itself is composed of layers, separated by a transition zone about 250 to 400 km thick. This new view of the inner core, which contains an inner-inner core, posits that the innermost layer of the core measures 1,180 km (733 miles) in diameter, making it less than half the size of the inner core. It has been further speculated that while the core is composed of iron, it may be in a different crystalline structure that the rest of the inner core.
What’s more, recent studies have led geologists to conjecture that the dynamics of deep interior is driving the Earth’s inner core to expand at the rate of about 1 millimeter a year. This occurs mostly because the inner core cannot dissolve the same amount of light elements as the outer core.
The freezing of liquid iron into crystalline form at the inner core boundary produces residual liquid that contains more light elements than the overlying liquid. This in turn is believed to cause the liquid elements to become buoyant, helping to drive convection in the outer core. This growth is therefore likely to play an important role in the generation of Earth’s magnetic field by dynamo action in the liquid outer core. It also means that the Earth’s inner core, and the processes that drive it, are far more complex than previously thought!
Yes indeed, the Earth is a strange and mysteries place, titanic in scale as well as the amount of heat and energy that went into making it many billions of years ago. And like all bodies in our universe, the Earth is not a finished product, but a dynamic entity that is subject to constant change. And what we know about our world is still subject to theory and guesswork, given that we can’t examine its interior up close.
As the Earth’s tectonic plates continue to drift and collide, its interior continues to undergo convection, and its core continues to grow, who knows what it will look like eons from now? After all, the Earth was here long before we were, and will likely continue to be long after we are gone.
Earth rotates through an entire day as captured in this animation of 22 still images taken on Sept. 17, 2015 by NASA’s Earth Polychromatic Imaging Camera (EPIC) camera on the Deep Space Climate Observatory (DSCOVR) spacecraft. Credits: NASA
The EPIC camera, which stands for Earth Polychromatic Imaging Camera (EPIC), is located a million miles away on the DSCOVR real time space weather monitoring satellite and is designed to take full disk color images of the sunlit side of our home planet multiple times per day.
The EPIC NASA images are literally just a finger tip away, after a 17 year wait to get the satellite into the launch queue since it was first proposed by former VP Al Gore. They are all easily viewed at NASA’s new EPIC camera website which went online today, Monday, October 19, 2015.
This EPIC image was taken on Oct.17 and shows the Australian continent and a portion of Asia.
EPIC image taken on Oct. 17, 2015 showing the continent of Australia and a portion of Asia. Credit: NASA
An annotated guide map illustration identifying the visible land masses accompanies each EPIC image and follows along as the Earth rotates daily.
What a great geography learning tool for student classrooms worldwide!
Annotated guide map identifying the visible land masses accompanies each EPIC image. Credit: NASA
DSCOVR is a joint mission between NOAA, NASA, and the U.S Air Force (USAF) that is managed by NOAA. The satellite and science instruments were provided by NASA and NOAA.
EPIC is a four megapixel CCD camera and telescope mounted on DSCOVR and orbiting around the L1 Lagrange Point – a neutral gravity point that lies on the direct line between Earth and the sun.
NASA says that once per day they will post “at least a dozen new color images of Earth acquired from 12 to 36 hours earlier” taken by the agency’s EPIC camera. The EPIC images will be stored in an archive searchable by date and continent.
The image sequence will show “the Earth as it rotates, thus revealing the whole globe over the course of a day.”
“The effective resolution of the DSCOVR EPIC camera is somewhere between 6.2 and 9.4 miles (10 and 15 kilometers),” said Adam Szabo, DSCOVR project scientist at NASA’s Goddard Space Flight Center, Greenbelt, Maryland, in a statement.
“The color Earth images are created by combining three separate single-color images to create a photographic-quality image equivalent to a 12-megapixel camera. The camera takes a series of 10 images using different narrowband filters — from ultraviolet to near infrared — to produce a variety of science products. The red, green and blue channel images are used to create the color images. Each image is about 3 megabytes in size.”
EPIC will capture “a constant view of the fully illuminated Earth as it rotates, providing scientific observations of ozone, vegetation, cloud height and aerosols in the atmosphere.”
Technician works on NASA Earth science instruments and Earth imaging EPIC camera (white circle) housed on NOAA/NASA Deep Space Climate Observatory (DSCOVR) inside NASA Goddard Space Flight Center clean room in November 2014. Credit: Ken Kremer/kenkremer.com
The couch sized probe was launched atop a SpaceX Falcon 9 on Feb. 11, 2015 from Cape Canaveral, Florida, to start the million mile journey to its deep space observation post at L1. The rocket was funded by the USAF.
The primary goal of the $340 million DSCOVR satellite is to monitor the solar wind and aid very important forecasts of space weather at Earth from L1.
L1 is located 1.5 million kilometers (932,000 miles) sunward from Earth. At L1 the gravity between the sun and Earth is perfectly balanced and the DSCOVR satellite orbits about that spot just like a planet.
The mission is vital because its solar wind observations are crucial to maintaining accurate space weather forecasts to protect US infrastructure such as power grids, aviation, planes in flight, all types of Earth orbiting satellites for civilian and military needs, telecommunications, ISS astronauts and GPS systems.
This animation shows images of the far side of the moon, illuminated by the sun, as it crosses between the DISCOVR spacecraft’s Earth Polychromatic Imaging Camera (EPIC) camera and telescope, and the Earth – one million miles away. Credit: NASA/NOAA
DSCOVR was first proposed in 1998 by then US Vice President Al Gore as the low cost ‘Triana’ satellite to take near continuous views of the Earth’s entire globe to feed to the internet as a means of motivating students to study math and science.
It was also dubbed “Goresat.”
The probe was eventually resurrected and partially rebuilt at NASA Goddard Space Flight Center as a much more capable Earth science satellite that would also conduct the space weather observations.
But Triana was shelved for purely partisan political reasons and the satellite was placed into storage at NASA Goddard.
Thus the practical and teachable science and daily scenes of the gorgeously rotating Earth were lost – until now!
Former VP Al Gore was clearly delighted with today’s launch of NASA’s EPIC website in this pair of tweets:
“Today @NASA launched its site for #DSCOVR’s daily images. I look forward to seeing more from #DSCOVR,” tweeted Al Gore.
“DSCOVR’s site displaying new daily images of Earth from L1 was launched today! Congratulations to all those who made this happen!”
Stay tuned here for Ken’s continuing Earth and planetary science and human spaceflight news.
NOAA/NASA Deep Space Climate Observatory (DSCOVR) undergoes processing in NASA Goddard Space Flight Center clean room. Solar wind instruments at right. DSCOVER launched in February 2015 atop SpaceX Falcon 9 rocket. Credit: Ken Kremer/kenkremer.comNOAA/NASA/USAF Deep Space Climate Observatory (DSCOVR) undergoes processing in NASA Goddard Space Flight Center clean room. Probe launched in February 2015 atop SpaceX Falcon 9 rocket. Credit: Ken Kremer/kenkremer.com
NOAA's DSCOVR satellite launches from Cape Canaveral Air Force Station on Feb. 11, 2015. DSCOVR will provide NOAA space weather forecasters more reliable measurements of solar wind conditions, improving their ability to monitor potentially harmful solar activity. Credit: Alan Walters/AmericaSpace
After a 17 year long wait, a new American mission to monitor intense solar storms and warn of impeding space weather disruptions to vital power grids, telecommunications satellites and public infrastructure was launched atop a SpaceXFalcon 9 on Wednesday, Feb. 11, from Cape Canaveral, Florida, to start a million mile journey to its deep space observation post.
The third time proved to be the charm when the Deep Space Climate Observatory, or DSCOVR science satellite lifted off at 6:03 p.m. EST Wednesday from Space Launch Complex 40 at Cape Canaveral Air Force Station in Florida.
The spectacular sunset blastoff came after two scrubs this week forced by a technical problem with the Air Force tracking radar and adverse weather on Sunday and Tuesday.
The $340 million DSCOVR has a critical mission to monitor the solar wind and aid very important forecasts of space weather at Earth at an observation point nearly a million miles from Earth. It will also take full disk color images of the sunlit side of Earth at least six times per day that will be publicly available and “wow” viewers.
Launch of NOAA DSCOVR satellite from Cape Canaveral Air Force Station on Feb. 11, 2015 to monitor solar storms and space weather. Credit: Julian Leek
The couch sized probe was targeted to the L1 Lagrange Point, a neutral gravity point that lies on the direct line between Earth and the sun located 1.5 million kilometers (932,000 miles) sunward from Earth. At L1 the gravity between the sun and Earth is perfectly balanced and the satellite will orbit about that spot just like a planet.
L1 is a perfect place for the science because it lies outside Earth’s magnetic environment. The probe will measure the constant stream of solar wind particles from the sun as they pass by.
The DSCOVR spacecraft (3-axis stabilized, 570 kg) will be delivered to the Sun-Earth L1 point, 1.5 million km (1 million miles) from the Earth, directly in front of the Sun. A Halo (Lissajous) orbit will stabilize the craft’s position around the L1 point while keeping it outside the radio noise emanating from the Sun. (Illustratin Credit: NASA)
DSCOVR is a joint mission between NOAA, NASA, and the U.S Air Force (USAF) that will be managed by NOAA. The satellite and science instruments are provided by NASA and NOAA. The rocket was funded by the USAF.
The mission is vital because its solar wind observations are crucial to maintaining accurate space weather forecasts to protect US infrastructure such as power grids, aviation, planes in flight, all types of Earth orbiting satellites for civilian and military needs, telecommunications, ISS astronauts and GPS systems.
It will take about 150 days to reach the L1 point and complete satellite and instrument checkouts.
DSCOVR will then become the first operational space weather mission to deep space and function as America’s primary warning system for solar magnetic storms.
It will replace NASA’s aging Advanced Composition Explorer (ACE) satellite which is nearly 20 years old and far beyond its original design lifetime.
“DSCOVR is the latest example of how NASA and NOAA work together to leverage the vantage point of space to both understand the science of space weather and provide direct practical benefits to us here on Earth,” said John Grunsfeld, associate administrator of NASA’s Science Mission Directorate in Washington.
DSCOVR was first proposed in 1998 by then US Vice President Al Gore as the low cost ‘Triana’ satellite to take near continuous views of the Earth’s entire globe to feed to the internet as a means of motivating students to study math and science. It was eventually built as a much more capable Earth science satellite that would also conduct the space weather observations.
But Triana was shelved for purely partisan political reasons and the satellite was placed into storage at NASA Goddard and the science was lost until now.
DSCOVR mission logo. Credit: NOAA/NASA/U.S. Air Force
DSCOVR is equipped with a suite of four continuously operating solar science and Earth science instruments from NASA and NOAA.
It will make simultaneous scientific observations of the solar wind and the entire sunlit side of Earth.
The 750-kilogram (1250 pound) DSCOVR probe measures 54 inches by 72 inches.
Technician works on NASA Earth science instruments and Earth imaging EPIC camera (white circle) housed on NOAA/NASA Deep Space Climate Observatory (DSCOVR) inside NASA Goddard Space Flight Center clean room in November 2014. Credit: Ken Kremer/kenkremer.com/AmericaSpace
The two Earth science instruments from NASA are the Earth Polychromatic Imaging Camera (EPIC) and the National Institute of Standards and Technology Advanced Radiometer (NISTAR).
EPIC will provide true color spectral images of the entire sunlit face of Earth at least six times per day, as viewed from an orbit around L1. They will be publically available within 24 hours via NASA Langley.
It will view the full disk of the entire sunlit Earth from sunrise to sunset and collect a variety of science measurements including on ozone, aerosols, dust and volcanic ash, vegetation properties, cloud heights and more.
Listen to my post launch interview with the BBC about DSCOVR and ESA’s successful IXV launch on Feb. 11.
NOAA/NASA Deep Space Climate Observatory (DSCOVR) undergoes processing in NASA Goddard Space Flight Center clean room. Solar wind instruments at right. DSCOVER will launch in February 2015 atop SpaceX Falcon 9 rocket. Credit: Ken Kremer/kenkremer.com/AmericaSpaceLaunch of NOAA DSCOVR satellite from Cape Canaveral Air Force Station on Feb. 11, 2015 to monitor solar storms and space weather. Credit: John StudwellPrelaunch view of SpaceX rocket on Cape Canaveral launch pad taken from LC-39 at the Kennedy Space Center. Credit: Chuck Higgins
NASA's Soil Moisture Active Passive (SMAP) observatory, on a United Launch Alliance Delta II rocket, is seen after the mobile service tower was rolled back Friday, Jan. 30 at Space Launch Complex 2, Vandenberg Air Force Base, Calif.
Image Credit: NASA/Bill Ingalls
NASA’s Soil Moisture Active Passive (SMAP) observatory, on a United Launch Alliance Delta II rocket, is seen after the mobile service tower was rolled back Friday, Jan. 30 at Space Launch Complex 2, Vandenberg Air Force Base, Calif. Image Credit: NASA/Bill Ingalls
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At dawn this morning (Jan. 31) NASA launched an advanced Earth science satellite aimed at making measurements of our planet’s surface soil moisture and freeze/thaw states from space that will revolutionize our understanding of the water, energy, and carbon cycles driving all life on Earth, aid weather forecasting and improve climate change models.
NASA’s new Soil Moisture Active Passive (SMAP) observatory thundered off the pad at 6:22 a.m. PST (9:22 a.m. EST) Saturday atop a two stage United Launch Alliance Delta II rocket from Space Launch Complex 2 on Vandenberg Air Force Base, California.
The $916 million satellite successfully separated from the rocket’s second stage some 57 minutes after the flawless liftoff and was injected into an initial 411- by 425-mile (661- by 685-kilometer) orbit. The spacecraft then deployed its solar arrays and telemetry indicated it was in excellent health.
“We’re in contact with SMAP and everything looks good right now,” NASA Launch Manager Tim Dunn said.
“Deployment of the solar arrays is underway. We just couldn’t be happier.”
SMAP separated from the second stage while pointed toward the sun as seen in the video below from a rocket mounted camera:
Video Caption: A camera on the second stage of the Delta II rocket captured this footage as the SMAP spacecraft pushed itself away from the rocket to complete the delivery of the Earth-observing spacecraft to its proper orbit following Jan. 31, 2015 liftoff. Credit: NASA TV/ULA
SMAP is NASA’s 1st Earth observing satellite designed to make high resolution global observations of Earth’s vital surface soil moisture content and freeze/thaw cycle just below your feet. It will aid global forecasting and have broad applications for science and society.
SMAP’s combined radar and radiometer instruments will peer into the top 2 inches (5 centimeters) of soil, through clouds and moderate vegetation cover, day and night, to produce the highest-resolution, most accurate soil moisture maps ever obtained from space, says NASA.
The blastoff of SMAP successfully concluded NASA’s ambitious plans to launch a record breaking total of five Earth science satellites in less than a year’s time.
“The launch of SMAP completes an ambitious 11-month period for NASA that has seen the launch of five new Earth-observing space missions to help us better understand our changing planet,” said NASA Administrator Charles Bolden.
“Scientists and policymakers will use SMAP data to track water movement around our planet and make more informed decisions in critical areas like agriculture and water resources.”
Artist’s rendering of the Soil Moisture Active Passive satellite. The width of the region scanned on Earth’s surface during each orbit is about 620 miles (1,000 kilometers). Image credit: NASA/JPL-Caltech
SMAP is projected to last for at least a three year primary mission.
The prior NASA Earth science instrument launched was the Cloud Aerosol Transport System (CATS) payload hauled to space by the SpaceX CRS-4 Dragon on Jan. 10, 2015 and recently installed on the exterior of the ISS. Read my CATS installation story – here.
“Congratulations to the NASA Launch Services Program team, JPL and all of our mission partners on today’s successful launch of the SMAP satellite,” said Jim Sponnick, ULA vice president, Atlas and Delta Programs.
“It is our honor to launch this important Earth science mission to help scientists observe and predict natural hazards, and improve our understanding of Earth’s water, energy and carbon cycles.”
SMAP will provide high-resolution, space-based measurements of soil moisture and its state — frozen or thawed — a new capability that will allow scientists to better predict natural hazards of extreme weather, climate change, floods and droughts, and help reduce uncertainties in our understanding of Earth’s water, energy and carbon cycles, according to a NASA description.
The mission will map the entire globe every two to three days for at least three years and provide the most accurate and highest-resolution maps of soil moisture ever obtained. The spacecraft’s final circular polar orbit will be 426 miles (685 kilometers), at an inclination of 98.1 degrees. The spacecraft will orbit Earth once every 98.5 minutes and repeat the same ground track every eight days.
“All subsystems are being powered on and checked out as planned,” Kent Kellogg, the SMAP project manager, during a post-launch press conference.
“Communications, guidance and control, computers and power are all operating nominally.”
The observatory is in excellent health. Its instruments will be turned on in 11 days.
Today’s blastoff of SMAP marks ULA’s second successful launch this month as well as the second of 13 planned for 2015. ULA’s first launch of 2015 was MUOS-3 from Cape Canaveral on Jan. 20.
ULA’s next launch involves NASA’s Magnetospheric Multiscale Mission (MMS) to study Earth’s magnetic reconnection. It is scheduled for launch on an Atlas V 421 booster on March 12 from Cape Canaveral. See my up close visit with MMS and NASA Administrator Charles Bolden at NASA Goddard Space Flight Center detailed in my story – here.
Stay tuned here for Ken’s continuing Earth and planetary science and human spaceflight news.
ISS-RapidScat data on a North Atlantic extratropical cyclone, as seen by the National Centers for Environmental Prediction Advanced Weather Interactive Processing System used by weather forecasters at the National Oceanic and Atmospheric Administration's Ocean Prediction Center.
Image Credit:
NASA/JPL-Caltech/NOAA
Barely two months after being launched to the International Space Station (ISS), NASA’s first science payload aimed at conducting Earth science from the station’s exterior has started its ocean wind monitoring operations two months ahead of schedule.
Data from the ISS Rapid Scatterometer, or ISS-RapidScat, payload is now available to the world’s weather and marine forecasting agencies following the successful completion of check out and calibration activities by the mission team.
Indeed it was already producing high quality, usable data following its power-on and activation at the station in late September and has monitored recent tropical cyclones in the Atlantic and Pacific Oceans prior to the end of the current hurricane season.
RapidScat is designed to monitor ocean winds for climate research, weather predictions, and hurricane monitoring for a minimum mission duration of two years.
“RapidScat is a short mission by NASA standards,” said RapidScat Project Scientist Ernesto Rodriguez of JPL.
“Its data will be ready to help support U.S. weather forecasting needs during the tail end of the 2014 hurricane season. The dissemination of these data to the international operational weather and marine forecasting communities ensures that RapidScat’s benefits will be felt throughout the world.”
ISS-RapidScat instrument, shown in this artist’s rendering, was launched to the International Space Station aboard the SpaceX CRS-4 mission on Sept. 21, 2014, and attached at ESA’s Columbus module. It will measure ocean surface wind speed and direction and help improve weather forecasts, including hurricane monitoring. Credit: NASA/JPL-Caltech/Johnson Space Center.
The 1280 pound (580kilogram) experimental instrument was developed by NASA’s Jet Propulsion Laboratory. It’s a cost-effective replacement to NASA’s former QuikScat satellite.
The $26 million remote sensing instrument uses radar pulses reflected from the ocean’s surface at different angles to calculate the speed and direction of winds over the ocean for the improvement of weather and marine forecasting and hurricane monitoring.
The RapidScat, payload was hauled up to the station as part of the science cargo launched aboard the commercial SpaceX Dragon CRS-4 cargo resupply mission that thundered to space on the company’s Falcon 9 rocket from Space Launch Complex-40 at Cape Canaveral Air Force Station in Florida on Sept. 21.
ISS-RapidScat is NASA’s first research payload aimed at conducting near global Earth science from the station’s exterior and will be augmented with others in coming years.
ISS-RapidScat viewed the winds within post-tropical cyclone Nuri as it moved parallel to Japan on Nov. 6, 2014, 05:30 UTC. Image Credit: NASA/JPL-Caltech
It was robotically assembled and attached to the exterior of the station’s Columbus module using the station’s robotic arm and DEXTRE manipulator over a two day period on Sept 29 and 30.
Ground controllers at Johnson Space Center intricately maneuvered DEXTRE to pluck RapidScat and its nadir adapter from the unpressurized trunk section of the Dragon cargo ship and attached it to a vacant external mounting platform on the Columbus module holding mechanical and electrical connections.
The nadir adapter orients the instrument to point its antennae at Earth.
The couch sized instrument and adapter together measure about 49 x 46 x 83 inches (124 x 117 x 211 centimeters).
“The initial quality of the RapidScat wind data and the timely availability of products so soon after launch are remarkable,” said Paul Chang, ocean vector winds science team lead at NOAA’s National Environmental Satellite, Data and Information Service (NESDIS)/Center for Satellite Applications and Research (STAR), Silver Spring, Maryland.
“NOAA is looking forward to using RapidScat data to help support marine wind and wave forecasting and warning, and to exploring the unique sampling of the ocean wind fields provided by the space station’s orbit.”
A SpaceX Falcon 9 rocket carrying a Dragon cargo capsule packed with science experiments and station supplies blasts off from Space Launch Complex 40 at Cape Canaveral Air Force Station, Florida, at 1:52 a.m. EDT on Sept. 21, 2014, bound for the ISS. Credit: Ken Kremer/kenkremer.com
This has been a banner year for NASA’s Earth science missions. At least five missions will be launched to space within a 12 month period, the most new Earth-observing mission launches in one year in more than a decade.
ISS-RapidScat is the third of five NASA Earth science missions scheduled to launch over a year.
NASA has already launched the of the Global Precipitation Measurement (GPM) Core Observatory, a joint mission with the Japan Aerospace Exploration Agency, in February and the Orbiting Carbon Observatory-2 (OCO-2) carbon observatory in July 2014.
Stay tuned here for Ken’s continuing Earth and Planetary science and human spaceflight news.
ISS-RapidScat instrument, shown in this artist's rendering, was launched to the International Space Station aboard the SpaceX CRS-4 mission on Sept. 21, 2014 and attached at ESA’s Columbus module. It will measure ocean surface wind speed and direction and help improve weather forecasts, including hurricane monitoring. Credit: NASA/JPL-Caltech/Johnson Space Center.
NASA inaugurated a new era of research for the International Space Station (ISS) as an Earth observation platform following the successful installation and activation of the ISS-RapidScat science instrument on the outposts exterior at Europe’s Columbus module.
The ISS Rapid Scatterometer, or ISS-RapidScat, is NASA’s first research payload aimed at conducting near global Earth science from the station’s exterior and will be augmented with others in coming years.
RapidScat is designed to monitor ocean winds for climate research, weather predictions, and hurricane monitoring.
The 1280 pound (580 kilogram) experimental instrument is already collecting its first science data following its recent power-on and activation at the station.
“Its antenna began spinning and it started transmitting and receiving its first winds data on Oct.1,” according to a NASA statement.
The first image from RapidScat was released by NASA on Oct. 6, shown below, and depicts preliminary measurements of global ocean near-surface wind speeds and directions.
Launched Sept. 21, 2014, to the International Space Station, NASA’s newest Earth-observing mission, the International Space Station-RapidScat scatterometer to measure global ocean near-surface wind speeds and directions, has returned its first preliminary images. Credit: NASA-JPL/Caltech
The $26 million remote sensing instrument uses radar pulses to observe the speed and direction of winds over the ocean for the improvement of weather forecasting.
“Most satellite missions require weeks or even months to produce data of the quality that we seem to be getting from the first few days of RapidScat,” said RapidScat Project Scientist Ernesto Rodriguez of NASA’s Jet Propulsion Laboratory, Pasadena, California, which built and manages the mission.
“We have been very lucky that within the first days of operations we have already been able to observe a developing tropical cyclone.
“The quality of these data reflect the level of testing and preparation that the team has put in prior to launch,” Rodriguez said in a NASA statement. “It also reflects the quality of the spare QuikScat hardware from which RapidScat was partially assembled.”
RapidScat, payload was hauled up to the station as part of the science cargo launched aboard the commercial SpaceX Dragon CRS-4 cargo resupply mission that thundered to space on the company’s Falcon 9 rocket from Space Launch Complex-40 at Cape Canaveral Air Force Station in Florida on Sept. 21.
Dragon was successfully berthed at the Earth-facing port on the station’s Harmony module on Sept 23, as detailed here.
It was robotically assembled and attached to the exterior of the station’s Columbus module using the station’s robotic arm and DEXTRE manipulator over a two day period on Sept 29 and 30.
Ground controllers at Johnson Space Center intricately maneuvered DEXTRE to pluck RapidScat and its nadir adapter from the unpressurized trunk section of the Dragon cargo ship and attached it to a vacant external mounting platform on the Columbus module holding mechanical and electrical connections.
Fascinating: #Canadarm & Dextre installed the #RapidScat Experiment on Columbus! @ISS_Research @NASAJPL @csa_asc. Credit: ESA/NASA/Alexander Gerst
The nadir adapter orients the instrument to point at Earth.
The couch sized instrument and adapter together measure about 49 x 46 x 83 inches (124 x 117 x 211 centimeters).
Engineers are in the midst of a two week check out process that is proceeding normally so far. Another two weeks of calibration work will follow.
Thereafter RapidScat will begin a mission expected to last at least two years, said Steve Volz, associate director for flight programs in the Earth Science Division, NASA Headquarters, Washington, at a prelaunch media briefing at the Kennedy Space Center.
RapidScat is the forerunner of at least five more Earth science observing instruments that will be added to the station by the end of the decade, Volz explained.
The second Earth science instrument, dubbed CATS, could be added by year’s end.
The Cloud-Aerosol Transport System (CATS) is a laser instrument that will measure clouds and the location and distribution of pollution, dust, smoke, and other particulates in the atmosphere.
CATS is slated to launch on the next SpaceX resupply mission, CRS-5, currently targeted to launch from Cape Canaveral, FL, on Dec. 9.
A SpaceX Falcon 9 rocket carrying a Dragon cargo capsule packed with science experiments and station supplies blasts off from Space Launch Complex 40 at Cape Canaveral Air Force Station, Florida, at 1:52 a.m. EDT on Sept. 21, 2014, bound for the ISS. Credit: Ken Kremer/kenkremer.com
This has been a banner year for NASA’s Earth science missions. At least five missions will be launched to space within a 12 month period, the most new Earth-observing mission launches in one year in more than a decade.
ISS-RapidScat is the third of five NASA Earth science missions scheduled to launch over a year.
NASA managers show installed location of ISS-RapidScat instrument on the ESA Columbus module on an ISS scale model at the Kennedy Space Center press site during launch period for the SpaceX CRS-4 Dragon cargo mission. Posing are Steve Volz, associate director for flight programs in the Earth Science Division, NASA Headquarters, Washington, and Howard Eisen, RapidScat Project Manager. Credit: Ken Kremer – kenkremer.com
Stay tuned here for Ken’s continuing Earth and Planetary science and human spaceflight news.
Learn more about Commercial Space Taxis, Orion and NASA Human and Robotic Spaceflight at Ken’s upcoming presentations:
Oct 14: “What’s the Future of America’s Human Spaceflight Program with Orion and Commercial Astronaut Taxis” & “Antares/Cygnus ISS Rocket Launches from Virginia”; Princeton University, Amateur Astronomers Assoc of Princeton (AAAP), Princeton, NJ, 7:30 PM
Oct 23/24: “Antares/Cygnus ISS Rocket Launch from Virginia”; Rodeway Inn, Chincoteague, VA
The NASA-ISRO Synthetic Aperture Radar (NISAR) mission, targeted to launch in 2020, will make global measurements of the causes and consequences of a variety of land surface changes on Earth. Image Credit: NASA
ISRO and NASA have inked a deal to collaborate on future missions to jointly explore the Red Planet and our Home Planet hot on the heels of ISRO’s wildly successful Mars Orbiter Mission (MOM), India’s first ever interplanetary voyager to explore Mars.
NASA Administrator Charles Bolden and K. Radhakrishnan, chairman of the Indian Space Research Organisation (ISRO), signed an agreement to collaborate on future science missions to explore Mars as well as to build and launch a joint NASA-ISRO mission to observe Earth.
The leaders of NASA and ISRO met in Toronto, Canada on Tuesday, Sept. 30 and “signed two documents to launch a NASA-ISRO satellite mission to observe Earth and establish a pathway for future joint missions to explore Mars,” according to a NASA statement.
Bolden and Rao met at the International Astronautical Congress underway in Toronto.
ISRO’s Mars Orbiter Mission captures the limb of Mars with the Mars Color Camera from an altitude of 8449 km soon after achieving orbit on Sept. 23/24, 2014. . Credit: ISRO
They signed one agreement defining each agency’s responsibilities for the joint NASA-ISRO Synthetic Aperture Radar (NISAR) mission, targeted to launch in 2020. NISAR will make global measurements of the causes and consequences of land surface changes.
The second agreement “establishes a NASA-ISRO Mars Working Group to investigate enhanced cooperation between the two countries in Mars exploration.”
“The signing of these two documents reflects the strong commitment NASA and ISRO have to advancing science and improving life on Earth,” said NASA Administrator Charles Bolden, in a NASA statement.
“This partnership will yield tangible benefits to both our countries and the world.”
NISAR will be the first Earth observing mission to be equipped two different synthetic aperture radar (SAR) frequencies (L-band and S-band) – one each from NASA and ISRO.
NASA will also provide “the high-rate communication subsystem for science data, GPS receivers, a solid state recorder, and a payload data subsystem.”
ISRO will provide the spacecraft bus and launch vehicle.
The radars will be able to measure subtle changes in Earth’s surface of less than a centimeter across stemming from the flow of glaciers and ice sheets as well as earthquakes and volcanoes.
Regarding Mars, the first subject the joint working group will tackle will be to coordinate observations from each nation’s recently arrived Mars orbiters – ISRO’s MOM and NASA’s MAVEN. They will also examine areas of future collaboration on surface rovers and orbiters.
“NASA and Indian scientists have a long history of collaboration in space science,” said John Grunsfeld, NASA Associate Administrator for Science.
“These new agreements between NASA and ISRO in Earth science and Mars exploration will significantly strengthen our ties and the science that we will be able to produce as a result.”
Stay tuned here for Ken’s continuing Earth and planetary science and human spaceflight news.
MAVEN is NASA’s next Mars orbiter and launched on Nov. 18, 2014, from Cape Canaveral, Florida. It will study the evolution of the Red Planet’s atmosphere and climate. Universe Today visited MAVEN inside the clean room at the Kennedy Space Center. With solar panels unfurled, this is exactly how MAVEN looks when flying through space and circling Mars and observing Comet Siding Spring. Credit: Ken Kremer/kenkremer.com
A SpaceX Falcon 9 rocket carrying a Dragon cargo capsule packed with science experiments and station supplies blasts off from Space Launch Complex 40 at Cape Canaveral Air Force Station, Florida, at 1:52 a.m. EDT on Sept. 21, 2014 bound for the ISS. Credit: Ken Kremer/kenkremer.com
KENNEDY SPACE CENTER, FL – A SpaceX Falcon 9 rocket blazed aloft on a spectacular middle of the night blastoff that turned night into day along the Florida Space coast today, Sept. 21, 2014, boosting a commercial cargo ship for NASA and loaded with 2.5 tons of ground breaking science experiments, 20 ‘mousetronauts’ and critical supplies for the human crew residing aboard the International Space Station (ISS).
The SpaceX Dragon cargo vessel on the CRS-4 mission thundered to space on the company’s Falcon 9 rocket from Space Launch Complex-40 at Cape Canaveral Air Force Station in Florida at 1:52 a.m. EDT Sunday, Sept. 21, just hours after a deluge of widespread rain showers inundated central Florida.
Notably, the Space CRS-4 mission is carrying NASA’s first research payload – RapidScat – aimed at conducting Earth science from the stations exterior.
“There’s nothing like a good launch, it’s just fantastic,” said Hans Koenigsman, vice president of Mission Assurance for SpaceX at the post launch briefing. “From what I can tell, everything went perfectly.”
“We worked very hard yesterday and weather wasn’t quite playing along and today everything was beautiful.”
CRS-4 marks the company’s fourth resupply mission to the ISS under a $1.6 Billion contract with NASA to deliver 20,000 kg (44,000 pounds) of cargo to the ISS during a dozen Dragon cargo spacecraft flights through 2016.
The Dragon spacecraft is loaded with more than 5,000 pounds of science experiments, spare parts, crew provisions, food, clothing, and supplies for the six person crews living and working aboard the ISS soaring in low Earth orbit under NASA’s Commercial Resupply Services (CRS) contract.
“This launch kicks off a very busy time for the space station,” said NASA’s Sam Scimemi, director of the International Space Station, noting upcoming launches of a Soyuz carrying the next three person international crew of the station and launches of other cargo spacecraft including the Orbital Sciences Antares/Cygnus around mid- October.
A SpaceX Falcon 9 rocket carrying a Dragon cargo capsule packed with science experiments and station supplies blasts off from Space Launch Complex 40 at Cape Canaveral Air Force Station, Florida, on Sept. 21, 2014 bound for the ISS. Credit: Ken Kremer/kenkremer.com
Today’s Falcon 9 launch had already been postponed 24 hours by continuing terrible weather all week long at Cape Canaveral which had also forced a more than two hour delay to the target liftoff of a United Launch Alliance Atlas V rocket from the Cape just four days earlier. Read my Atlas V launch story involving the completely clandestine CLIO satellite – here.
Rather amazingly given the awful recent weather, Falcon 9 streaked to orbit under a beautifully star filled nighttime sky.
Sunday’s launch brilliantly affirmed the ability of SpaceX to fire off their Falcon 9 rockets at a rapid pace since it was the second launch in less than two weeks, and the fourth over the past ten weeks. The prior Falcon 9 successfully launched the AsiaSat 6 commercial telecom satellite from the Cape on Sept. 7 – detailed here.
The CRS-4 missions marks the birth of a new era in Earth science aboard the massive million pound orbiting space station. The trunk of the Dragon is loaded with the $30 Million ISS-Rapid Scatterometer to monitor ocean surface wind speed and direction.
RapidScat is NASA’s first research payload aimed at conducting Earth science from the station’s exterior. The station’s robot arm will pluck RapidScat out of the trunk and attach it to an Earth-facing point on the exterior trusswork of ESA’s Columbus science module.
Dragon also carries the first 3-D printer to space for studies by the astronaut crews over at least the next two years.
SpaceX Falcon 9 erect at Cape Canaveral launch pad 40 awaiting launch on Sept. 21, 2014 on the CRS-4 mission. Credit: Ken Kremer – kenkremer.com
The science experiments and technology demonstrations alone amount to over 1644 pounds (746 kg) of the Dragon’s cargo and will support 255 science and research investigations that will occur during the station’s Expeditions 41 and 42 for US investigations as well as for JAXA and ESA.
After a two day orbital chase, Dragon will rendezvous with the station on Tuesday morning, Sept. 23. It will be grappled at 7:04 a.m. by Expedition 41 Flight Engineer Alexander Gerst of the European Space Agency, using the space station’s robotic arm and then berthed at an Earth-facing port on the station’s Harmony module. NASA astronaut Reid Wiseman will support Gerst.
NASA TV is expected to provide live coverage of Dragon’s arrival, grappling, and station berthing.
Dragon was launched aboard the newest, more powerful version of the Falcon 9, dubbed v1.1, powered by a cluster of nine of SpaceX’s new Merlin 1D engines that are about 50% more powerful compared to the standard Merlin 1C engines. The nine Merlin 1D engines’ 1.3 million pounds of thrust at sea level rises to 1.5 million pounds as the rocket climbs to orbit.
The Merlin 1 D engines are arrayed in an octaweb layout for improved efficiency.
Therefore the upgraded Falcon 9 can boost a much heavier cargo load to the ISS, low Earth orbit, geostationary orbit and beyond.
The maiden launch of the Falcon 9 v1.1 took place in December 2013.
The next generation Falcon 9 is a monster. It measures 224 feet tall and is 12 feet in diameter. That compares to a 130 foot tall rocket for the original Falcon 9.
At the 3:30 am NASA post launch news conference it’s all smiles and congratulations on the successful SpaceX launch to the ISS from the Kennedy Space Center Florida. From L/R NASA Kennedy Space Center News Chief Mike Curie, NASA Director International Space Station Sam Scimemi and SpaceX VP of Mission Assurance Dr. Hans Koenigsmann. Credit: Julian Leek
Overall it’s been a great week for SpaceX. The firm was also awarded one of two NASA contracts to build a manned version of the Dragon, dubbed V2, that will ferry astronaut crews to the ISS starting as soon as 2017. Read my story – here.
The second ‘space taxi’ contract was awarded Boeing to develop the CST-100 crew transporter to end the nation’s sole source reliance on Russia for astronaut launches in 2017.
Dragon V2 will launch on the same version of the Falcon 9 launching today’s CRS-4 cargo Dragon.
Stay tuned here for Ken’s continuing SpaceX, Boeing, Sierra Nevada, Orbital Sciences, commercial space, Orion, Mars rover, MAVEN, MOM and more Earth and Planetary science and human spaceflight news.
A SpaceX Falcon 9 rocket carrying a Dragon cargo capsule packed with science experiments and station supplies blasts off from Space Launch Complex 40 at Cape Canaveral Air Force Station, Florida, at 1:52 a.m. EDT on Sept. 21, 2014 bound for the ISS. Credit: Ken Kremer/kenkremer.com
![Computer simulation of the Earth's field in a period of normal polarity between reversals.[1] The lines represent magnetic field lines, blue when the field points towards the center and yellow when away. The rotation axis of the Earth is centered and vertical. The dense clusters of lines are within the Earth's core](https://www.universetoday.com/wp-content/uploads/2010/03/Geodynamo_Between_Reversals-e1449100829326.gif)
