The history of dust, through space and time

What is dust?

It is ridiculous to ask this question in India. Dust is everywhere. On the roads, in the nose, in the lungs. You lock your house, go on vacation for a month, you come back and you will notice a beautiful patina on the table. It is inside your laptop that the cooling fan nuts are driven.

It constitutes nightmarish storms on Mars. Philip Pullman and Steven Erikson have written fantasy books about him. Dust is ubiquitous. (The only dust-free places I've seen are in archival photos on the Internet.)

But what exactly is it and where does it come from? he?

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Earth

Dust is fine particles. It comes from a wide variety of sources. Atmospheric dust – or wind – that we know so much is composed of small particles sheared on solid objects. For example, rapidly blowing winds sweep particles of loose, dry soil into the air, giving rise to what is called fugitive dust. The smoke from the exhaust pipes is another source.

Another source is mites of the Pyroglyphidae family. They eat skin flakes, including those excreted by humans, and digest them with enzymes that remain in their poop. In your home, exposure to their poop (considered a dust) can trigger asthma attacks.

Winds lift particles off the surface of the Earth and carry them into the troposphere. Once the dust rises, it acts as an aerosol. It retains heat and warms the surface of the Earth. Once they are collected in sufficient quantities, they begin to affect the weather conditions of the regions below, including rainfall patterns.

Dust particles smaller than 10 microns penetrate your lungs and affect your respiratory health. They conspire with other pollutants and, taking advantage of the slow winds, stagnate in the National Capital Region of India during the winter. Particles smaller than 2.5 microns "increase the risk of mortality by age" (source) and significantly increase the number of hospital admissions.

There are also dusts that travel thousands of kilometers to reach very remote areas of the world. The Sahara is the largest source of desert dust in the world, according to a study. In June of this year, the tropical region of the Atlantic Ocean experienced its most dusty period in 15 years, with a huge wave that devastated north-eastern Chad to the center of the Americas. According to NASA's Earth Observatory, Saharan dust "contributes to beach development in the Caribbean and soil fertilization in the Amazon."

This is not a thin note on your screen this morning #GOESEast captured a full disc view of the Saharan Major Earth #dust blowing through l & # 39; Atlantic. https://t.co/P1F11zXUHI pic.twitter.com/JzwebkGibx

– NOAA Satellites (@NOAASatellites) June 27, 2018

But speaking of dust that migrate to at great distances, the transatlantic plume seems much less a journey than the dust brought to Earth by meteorites that have traveled hundreds of thousands of kilometers in space. When these rocks move towards the ground, the atmosphere burns dust in the form of dust, leaving them suspended in the upper atmosphere.

The atoms released by these particles in the mesosphere drift into the planet's circulation system, moving from one pole to the other. pole over several months. They interact with other particles to leave a trail of charged particles. Scientists then use a radar to track these particles and learn more about the circulation itself. Some extraterrestrial dust particles also reach the surface of the Earth over time. They could carry imprints of physical and chemical reactions that they could have encountered in space, even for billions of years.

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Orbit

In the mid-twentieth century, researchers used optical data and mathematical arguments to demonstrate that about four million tonnes of meteorite hit the atmosphere of our planet every year. This situation is alarming: the figure suggests that the number of meteorites in the space is much higher than expected. In turn, the threat to our satellites could have been underestimated. More careful badessments subsequently lowered the figure. A 2013 report indicates that 10 to 40 tons of meteoric dust enter the Earth's atmosphere each day.

Yet this figure is not small – and its effects are exacerbated by debris that humans themselves orbit around the Earth. The Wikipedia article on "Space Debris" carefully notes: "As of … July 2016, the US Strategic Command has detected a total of 17,852 artifacts in orbit over the Earth, of which 1 419 operational satellites. "But a single line later, the number The amount of objects less than 1 cm explodes up to 170 million.

If a dust of 0.00001 kg carried by a breeze of 1.4 m / s hits your face, you will not feel anything. Indeed, its momentum – the product of its mbad and its speed – is very weak. But when a particle weighing one hundredth of a gram hits a satellite at a relative speed of 1.5 km / s, its speed is a thousand times higher. Suddenly, it is able to damage critical components and fine study surfaces, ending millions of dollars in multi-year missions in seconds. One study suggests that such particles, if they travel fast enough, can also generate tiny shock waves.

Before our next stop on Dust Voyage, let's take a break in science fiction. The mid-century overestimation of the flow of meteoric dust may have prompted Arthur C. Clarke to write his 1961 novel, A Fall of Moondust . In the narrative, a cruise ship called Selene takes tourists over a basin of ultrafine dust, apparently of meteoric origin. But one day, a natural disaster sank the Selene in the dust, preventing its pbadengers from living in conditions putting their lives in danger. After much desperation, a rescue mission is organized when an astronomer landmarks from space a thermal trail indicating the location of Selene, aboard a spaceship called Lagrange II .

This name is a reference to the famous Lagrange Points. As the Earth rotates around the Sun and the Moon turns around the Earth, their combined gravitational fields give rise to five points in the space where the force acting on an object is perfectly suited to maintaining its relative position. to the Earth and the Sun. They are called L1, L2, L3, L4 and L5.

The Indian Space Research Organization (ISRO) plans to launch its Aditya satellite for the study of the Sun at N1. This is useful because in L1, the vision of the Sun Aditya will not be blocked by the Earth. However, objects in L1, L2 and L3 have an unstable equilibrium. Without maintenance measures from time to time, they tend to disengage from their positions.

But this is not the case with L4 and L5, objects for which the equilibrium remains more stable. And like everything that's been hanging around for a while, they're picking up dust.

In the 1950s, Polish astronomer Kazimierz Kordylewski claimed to have spotted two clouds of dust at L4 and L5. These nebulous collections of particles have since been called Kordylewski clouds. Other astronomers, however, have disputed their existence. For example, the Hiten satellite did not find any significant dust concentrations in the L4 and L5 regions in 2009. Some argued that Hiten might have missed them because the dust clouds were too scattered.

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Space

Just two weeks ago, Hungarian astronomers claimed to have confirmed the presence of dust clouds in these regions (their papers here and here). Since the L4 and L5 regions are of interest for future space missions, astronomers will now have to validate this result and, if necessary, evaluate the dust density and the threat probabilities that result.

Unlike Kordylewski, who took photographs of At the top of a mountain, the Hungarian group relied on the ability of dust to polarize light. Light is electromagnetic radiation. Each light wave consists of an electric field and a magnetic field oscillating perpendicularly. Imagine different waves of light approaching the dust, their electric fields directed in arbitrary directions. After striking the dust, the particles polarize the waves, forcing all the electric fields to align with a particular orientation.

When astronomers detect such light, they know that she has encountered dust in her path. With the help of different instruments and badytical techniques, they can then map the distribution of dust in the space through which light pbades.

This is how the Planck telescope of the European Space Agency was able to draw a glimpse of the dust around him. the Milky Way.

It's billions and billions of tons. In comparison, are your complaints about dust around the house pale?

And even on this scale, it was a nuisance. We do not know if the galaxy is complaining, but Brian Keating certainly.

In March 2014, Keating and his team at the Center for Astronomy at Harvard University announced they had discovered signs of increasing the volume of the universe. ⁸⁰ in only 10 ^-33 seconds after his birth in the Big Bang. About 380,000 years later, the Big Bang's radiation remnants – known as the Cosmic Microwave Background (CMB) – were created. Keating et al used the BICEP2 detector at the South Pole to find cosmic inflation footprints on the CMB. The smoking gun: light of a certain wavelength polarized by the gravitational waves of the beginning of the universe.

While the announcement was made with great fanfare – as "discovering the decade" and so on, their application quickly became suspect. Data from the Planck telescope and other observatories quickly showed that what Keating's team had discovered was actually light polarized by galactic dust. Just like that, their ambition to win a Nobel Prize has collapsed. From ashes to ashes, from dust to dust.

You probably ask, "Did not he do enough? Can we stop now? "No. We must persevere, because the dust has done even more and we have come so close. For example, look at the map of the Milky Way. Where can all this dust come from?

It is here that the history of dust takes a more favorable turn. We have all heard that we are made of star dust. It would certainly be futile to try to determine where our dust comes from, but to understand the dust itself, we must look to the stars.

Storms on Earth or on Mars that attract dust in the air are only weak blasts against the colossal turbulence of stellar ruin. Stars can die in different ways depending on their size. Supernovae are the most spectacular. In a standard Type 1a supernova, a whole white dwarf star undergoes nuclear fusion, disintegrating completely and throwing material at more than 5,000 km / s. More mbadive stars undergo a collapse of the nucleus, expelling their outermost layers in the space of a fatal sneeze before what remains is involved in a neutron star or a black hole.

In all cases, the material released into space forms giant clouds that disperse slowly. over millions of years. If they are in the presence of a black hole, they are then trapped in an accretion disk, accelerated, heated and excited by radiation and magnetic fields. The lucky ones can float to meet other stars, planets or other objects, or even run into other clouds of dust and gas. These interactions are very difficult to model – but there is no doubt that all these interactions are essentially dictated by the four fundamental forces of nature.

One of them is the force of gravity. When a gas / dust cloud becomes so large that its collective gravitational attraction prevents it from dispersing, it can then collapse to form another star and live in another era.

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Together

Thus, stars are cosmic engines. They keep matter – including dust – moving. They may not be the only ones to do so, but given the presence of stars throughout the (observable) universe, they certainly play a major role. When they do not animate or exit their lives, their gravitational attraction influences the trajectories of other smaller bodies around them, including comets, asteroids, and other space rocks.

It is considered that the solar system itself has been condensed. from a large disk of dirt and dust made up of various elements surrounding a young Sun – a disc of remains of the birth of the star. Different planets have formed depending on the availability of different volumes of different materials at different times. It is believed that Jupiter came first and the inner planets, including the Earth, came last.

But it does not matter; life here had everything she needed to take root. Scientists are still figuring out what these ingredients might have been and where they came from. According to one theory, they included carbon and hydrogen compounds called polycyclic aromatic hydrocarbons, and they first formed – you guessed it – among winding dust across the planet. ;space.

They could then have been transported to Earth by meteors and comets, perhaps tilted to Earth's orbit by the gravity of the Sun. When a comet approaches a star, for example, the material on its surface begins to evaporate, forming a trail of gas and dust. When the Earth crosses an area where the remains of the tail and other small pieces of rock accumulate, they enter the atmosphere in the form of meteorite rain.

Dust is really ubiquitous and the credit due to it is rare. This has been and continues to be a painful part of everyday life. However, contrary to our research up here from the extraterrestrial company, we are not the only ones to feel badaulted by dust.