Tag: earth

A NASA Spacecraft Is About To Slingshot Around Earth To Meet Up With An Asteroid

On Friday, a spacecraft the size of an SUV will slingshot around Earth’s South Pole, altering its trajectory through space.

The probe is NASA’s OSIRIS-REx, and its upcoming maneuver around our planet is known as a gravity assist — a way to harness Earth’s gravity to alter its orbit.

The move is critical, since it will put OSIRIS-REx on course to meet up with an asteroid in the fall of 2018.

OSIRIS-REx launched last year with a relatively straightforward purpose: grab a sample of rocks from an asteroid and bring them back to Earth.

If all goes well, the vehicle should retrieve the largest sample ever collected from an asteroid, and give scientists the chance to study the space rock components in more detail than ever before.

But first, the probe has to reach its target — a nearby asteroid named Bennu.




NASA picked Bennu partly because the asteroid’s orbit is similar to Earth’s orbit, and that makes it an easier target to reach.

But their paths aren’t the exact same: Bennu’s orbit is tilted by about six degrees compared to Earth’s. In the past year, OSIRIS-REx has been orbiting in the same plane as Earth, traveling slightly ahead of our planet.

And now it’s time for OSIRIS-REx to match Bennu’s orbit in space.

There are two main options to change a spacecraft’s trajectory: one is to use the vehicle’s onboard engines to propel the spacecraft in a certain direction.

The problem with this option is that it uses up the spacecraft’s finite amount of fuel. And OSIRIS-REx would have needed a lot of fuel to alter its course to reach Bennu in time — more than the vehicle is carrying.

So instead, the probe’s navigators opted to use the second option — a gravity assist. “This was the only option to reach Bennu, launching in 2016,” Michael Moreau, a flight engineer at NASA’s Goddard Space Flight Center said.

This maneuver has been used on many previous space missions, to increase or decrease a spacecraft’s speed and course. It’s essentially an exchange of energy, similar to when a roller coaster speeds up while going down a hill.

When OSIRIS-REx swings by Earth, it will steal a little bit of our planet’s momentum in order to change its orbit. Earth is so massive that the maneuver won’t really affect our planet.

But OSIRIS-REx will change its speed and course by more than 8,400 miles per hour. That’s nearly twice the amount the spacecraft would get if it used up all its fuel.

OSIRIS-REx will approach the Earth at a speed of 19,000 miles per hour, flying over Australia first. It will then make its closest approach to Earth at 12:52PM ET, coming within 11,000 miles of Antarctica.

Around that time, the vehicle will lose contact with NASA since it will be out of range with the space agency’s closest tracking stations.

The blackout should last just 50 minutes, though, and NASA expects to regain communications around 1:40PM ET.

The vehicle is also supposed to come into areas dominated by satellites, but NASA says it has taken steps to make sure no collisions happen during the assist.

After Friday’s maneuver, OSIRIS-REx will cruise through space for another year, reaching Bennu in October.

At that point, the vehicle is supposed to fly around the asteroid for two years, surveying the rock’s surface, before actually grabbing the coveted sample and returning to Earth.

The gravity assist is the first step to getting there, and it’ll allow the mission team to meet up with Bennu exactly when they needed to, while saving on fuel.

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Why It Is So Hard To Predict Where And When Earthquakes Will Strike?

Can earthquakes ever be predicted? This question is timely after the magnitude 7.8 earthquake that struck Nepal recently. If authorities had more warning that the earthquake was coming, they may have been able to save more lives.

While Nepal is a documented area of previous seismic activity, at the moment there is no technique that provides predictions of sufficient clarity to allow for evacuations at short notice.

So if we cannot predict these events now, are there avenues of research to provide useful predictions in the future?

The key word here is “useful”. It is possible to make long-term forecasts about future earthquake activity, partly by using the past record of earthquakes as a guide.

There is no reason to believe that a region of the Earth is going to behave differently in the next few thousands of years from its pattern over the same range back in time.




In the short term, seismologists can draw on data from recording stations, with records going back roughly 40 years on a global scale.

Within hours of a major earthquake there are estimates of its epicentre, magnitude (the amount of energy released), the depth at which it originated, the orientation of the geological fault that caused it and the direction in which it moved.

The event in Nepal was a thrust fault, meaning that the upper part of the Earth was shortened by a few metres, with the rock lying above the fault plane moving southwards over the rock lying beneath it.

Gathering the data

Information about past earthquakes comes from a number of sources, not least historical records. But such records are incomplete, even in earthquake-prone countries with long traditions of documenting natural disasters, such as China and Iran.

Other lines of evidence are available, including measuring and dating the offsets of man-made or natural features that can be accurately dated, such as the walls of a castle or a city. Faults cutting the Great Wall of China have been documented in this way.

Seismologists also dig trenches across faults known or suspected to be active, and can recover rocks and sediments affected by earthquakes.

These events can dated, for example by radiocarbon analysis of plant remains disturbed by the faulting.

By combining the earthquake ages with the size of the damaged areas, it is possible to understand earthquake patterns over hundreds or even thousands of years.

Scientists use this information as a guideline for future behaviour, but it is clear that the faults do not slip after the same period of time between earthquakes.

Nor does a fault necessarily rupture in the same place in successive earthquakes.

An earthquake releasing stress along one fault segment may place more stress on an adjacent region, thereby increasing the earthquake likelihood in that area.

This may occur soon after the original event, which explains the phenomenon of aftershocks. Nepal has already seen aftershocks of a magnitude greater than six, and is likely to see more.

Global hotspots

Instrumental and historical records combine to make a global picture of earthquake activity. There are, unfortunately, many danger areas.

Eurasia bears the brunt, because of the collision of the Indian and Arabian plates with the rest of Eurasia. Therefore China, Iran, Pakistan and India all share Nepal’s susceptibility to large earthquakes.

Other danger areas lie along the margins of the Pacific and Indian oceans, where one plate slides under another in a process called subduction. Earthquakes at such plate boundaries can cause devastating tsunamis, like in Japan in 2011.

Newer lines of research include precise measurements of the movement of a fault during earthquakes and the motion of the Earth’s surface between earthquakes.

Across the Himalayas there is around 20mm of convergence (shortening) every year, roughly half of the overall convergence between the Indian and Eurasian plates.

The remainder is accommodated further north, in ranges such as the Tian Shan and the Tibetan Plateau.

In other words, every year a person in Siberia becomes roughly 40 mm closer to a person in central India, as the Earth’s crust deforms across the broad region between them.

This strain builds up over time and is released in an earthquake like the snapping of an elastic band.

Faster strain, longer faults and greater strength in the upper part of the Earth in a particular region can all lead to larger earthquakes.

The Himalayas feature a deadly combination of these factors, leading to very large events of the kind experienced on April 25.

It is not sensible to be naively optimistic about improvements in earthquake prediction, but all research on the past and present behaviour of active faults is to be welcomed.

It is timely that the UK’s Natural Environment Research Council has just announced funding for research into earthquakes and resilience to earthquakes.

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Detecting Magnetic Fields On Brown Dwarfs And Exoplanets

Mysterious objects called brown dwarfs are sometimes called “failed stars.

They are too small to fuse hydrogen in their cores, the way most stars do, but also too large to be classified as planets.

But a new study in the journal Nature suggests they succeed in creating powerful auroral displays, similar to the kind seen around the magnetic poles on Earth.

This is a whole new manifestation of magnetic activity for that kind of object,” said Leon Harding, a technologist at NASA’s Jet Propulsion Laboratory, Pasadena, California, and co-author on the study.

On Earth, auroras are created when charged particles from the solar wind enter our planet’s magnetosphere, a region where Earth’s magnetic field accelerates and sends them toward the poles.

There, they collide with atoms of gas in the atmosphere, resulting in a brilliant display of colors in the sky.




As the electrons spiral down toward the atmosphere, they produce radio emissions, and then when they hit the atmosphere, they excite hydrogen in a process that occurs at Earth and other planets,” said Gregg Hallinan, assistant professor of astronomy at the California Institute of Technology in Pasadena, who led the team.

We now know that this kind of auroral behavior is extending all the way from planets up to brown dwarfs.

Brown dwarfs are generally cool, dim objects, but their auroras are about a million times more powerful than auroras on Earth, and if we could somehow see them, they’d be about a million times brighter, Hallinan said.

Additionally, while green is the dominant color of earthly auroras, a vivid red color would stand out in a brown dwarf’s aurora because of the higher hydrogen content of the object’s atmosphere.

The foundation for this discovery began in the early 2000s, when astronomers began finding radio emissions from brown dwarfs.

This was surprising because brown dwarfs do not generate large flares and charged-particle emissions the way the sun and other kinds of stars do. The cause of these radio emissions was a big question.

Harding, working as part of Hallinan’s group while pursuing his doctoral studies, found that there was also periodic variability in the optical wavelength of light coming from brown dwarfs that pulse at radio frequencies.

He published these findings in the Astrophysical Journal.

Harding built an instrument called an optical high-speed photometer, which looks for changes in the light intensity of celestial objects, to examine this phenomenon.

In this new study, researchers examined brown dwarf LSRJ1835+3259, located about 20 light-years from Earth.

Scientists studied it using some of the world’s most powerful telescopes the National Radio Astronomy Observatory’s Very Large Array, Socorro, New Mexico, and the W.M. Keck Observatory’s telescopes in Hawaii in addition to the Hale Telescope at the Palomar Observatory in California.

Given that there’s no stellar wind to create an aurora on a brown dwarf, researchers are unsure what is generating it on LSRJ1835+3259.

An orbiting planet moving through the magnetosphere of the brown dwarf could be generating a current, but scientists will have to map the aurora to figure out its source.

The discovery reported in the July 30, 2015 issue of Nature could help scientists better understand how brown dwarfs generate magnetic fields.

Additionally, brown dwarfs will help scientists study exoplanets, planets outside our solar system, as the atmosphere of cool brown dwarfs is similar to what astronomers expect to find at many exoplanets.

It’s challenging to study the atmosphere of an exoplanet because there’s often a much brighter star nearby, whose light muddles observations. But we can look at the atmosphere of a brown dwarf without this difficulty,” Hallinan said.

Hallinan also hopes to measure the magnetic field of exoplanets using the newly built Owens Valley Long Wavelength Array, funded by Caltech, JPL, NASA and the National Science Foundation.

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How Do We Know That Global Warming Is Real?

The Earth’s climate has changed throughout history.

Just in the last 650,000 years there have been seven cycles of glacial advance and retreat, with the abrupt end of the last ice age about 7,000 years ago marking the beginning of the modern climate era and of human civilization.

Most of these climate changes are attributed to very small variations in Earth’s orbit that change the amount of solar energy our planet receives.

The current warming trend is of particular significance because most of it is extremely likely to be the result of human activity since the mid-20th century and proceeding at a rate that is unprecedented over decades to millennia.




Earth-orbiting satellites and other technological advances have enabled scientists to see the big picture, collecting many different types of information about our planet and its climate on a global scale.

This body of data, collected over many years, reveals the signals of a changing climate.

The heat-trapping nature of carbon dioxide and other gases was demonstrated in the mid-19th century.

Their ability to affect the transfer of infrared energy through the atmosphere is the scientific basis of many instruments flown by NASA.

There is no question that increased levels of greenhouse gases must cause the Earth to warm in response.

Ice cores drawn from Greenland, Antarctica, and tropical mountain glaciers show that the Earth’s climate responds to changes in greenhouse gas levels.

Ancient evidence can also be found in tree rings, ocean sediments, coral reefs, and layers of sedimentary rocks.This ancient, or paleoclimate, evidence reveals that current warming is occurring roughly ten times faster than the average rate of ice-age-recovery warming.

This ancient, or paleoclimate, evidence reveals that current warming is occurring roughly ten times faster than the average rate of ice-age-recovery warming.

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NASA’s Cassini Spacecraft Will Meet Its Fiery End In Saturn’s Atmosphere On Friday

After 13 years of zooming around Saturn and its many moons, NASA’s Cassini spacecraft has less than four days left at the planetary system before the probe is lost forever. Early Friday morning, Cassini will dive into Saturn’s atmosphere, eventually melting and breaking apart.

The death plunge will put an end to the spacecraft’s mission, one that has taught us more about Saturn and its moons than we ever thought possible.

This final step has long been planned by the Cassini mission team, and it’s meant to protect the Saturn system.

Two of the planet’s moons — Enceladus, with its subsurface ocean, and Titan, with lakes of methane — may have the right conditions to harbor life.




By destroying Cassini, NASA ensures the spacecraft will never accidentally wander near the moons and contaminate them with microbes that may have hitched a ride from Earth.

In April, NASA maneuvered Cassini into its final stage, known as the “Grand Finale” — a path that takes the vehicle between Saturn and its famous rings, and closer to the planet than ever before.

During these week-long orbits, the probe has been gathering some of its most crucial data yet. But the planet’s gravity will eventually get the best of Cassini after the 22nd Grand Finale orbit, pulling the spacecraft into the planet at 6:31AM ET on Friday.

The navigators have no more maneuvers to do,” Scott Edgington, the deputy project scientist for Cassini, tells The Verge. We’re guaranteed to go into Saturn, no matter what happens.

Once Cassini enters Saturn’s atmosphere, it will only be five or six minutes before the probe is taken apart. During the plunge, its instruments will be getting up-close measurements that will be sent back to Earth in real time.

All that data will probably keep researchers busy for awhile. “Some of these analyses will take years for scientists to figure out,” says Edgington. “I would expect to still hear a lot more from in the coming years.

Cassini’s destruction has been in the making for nearly a decade now. The spacecraft was launched in 1997, and it was the first probe intended to orbit and thoroughly study the Saturn system.

After arriving at the planet in 2004, Cassini dropped a probe that landed on Titan, and began mapping out Saturn’s rings and moons, among many other science tasks.

After four years, Cassini’s primary mission ended. But the spacecraft was still fully operational, and the mission team wanted to come up with ways to extend Cassini’s time at Saturn while preserving Enceladus and Titan.

It couldn’t last forever: the spacecraft only has a limited amount of fuel, and eventually the team would lose the ability to maneuver Cassini in space.

So the team came up with a number of different options: one idea was to eject Cassini from the Saturn system.

So far, those orbits have been fruitful. The mission team has learned that the gap between Saturn and its rings is relatively free of large particles, something they didn’t expect.

Plus, the researchers have gotten more in-depth measurements of the structure of Saturn’s magnetic field.

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A Really, Really Big Asteroid Is Going To Fly Past Earth Today!

Today, a three-mile-wide asteroid is going to fly past Earth – the biggest space rock to pass our planet this close in a century.

Asteroid 1981 ET3 – also known as 3122 Florence – will fly past safely today, September 1, 18 times further away than the moon.

While many known asteroids have passed by closer to Earth than Florence will on September 1, all of those were estimated to be smaller,” said Paul Chodas, manager of NASA’s Center for Near-Earth Object Studies (CNEOS) at the agency’s Jet Propulsion Laboratory.




Florence is the largest asteroid to pass by our planet this close since the NASA program to detect and track near-Earth asteroids began.

The asteroid, named for Florence Nightingale, was first spotted in 1981, and the flyby in September will be the closest it’s come to Earth since 1890.

Asteroid Florence was discovered by Schelte “Bobby” Bus at Siding Spring Observatory in Australia in March 1981.

It is named in honor of Florence Nightingale (1820-1910), the founder of modern nursing.

The 2017 encounter is the closest by this asteroid since 1890 and the closest it will ever be until after 2500.

This relatively close encounter provides an opportunity for scientists to study this asteroid up close.

Florence is expected to be an excellent target for ground-based radar observations – and will also be visible to amateur astronomers via telescopes.

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Mountain Forest Growth Has Established The Earth’s Climate For Millions Of Years

The Earth’s atmospheric carbon dioxide has remained remarkably stable over the past 24 million years.

And scientists believe they have now solved part of the mystery as to why this has been the case, despite changing geological conditions.

They believe that ancient tree roots in the mountains may play an important role in controlling long-term global temperatures acting as a type of natural ‘thermostat’.

When CO2 levels became too low for plants to grow properly, forests in mountains appear to have kept the climate in check by slowing down the removal of carbon dioxide from the atmosphere.




This study shows how trees can act as brakes on extreme climate change, and the roots of trees in tropical mountains such as the Andes play a disproportionate role,” Yadvinder Malhi, professor of Ecosystem Science at Oxford University said.

However, these responses take thousands to millions of years and cannot do much to slow the rate of global warming we are experiencing this century.

Researchers from Oxford and Sheffield Universities discovered that temperatures affect the thickness of the leaf litter and organic soil layers, as well as the rate at which the tree roots grow.

In a warmer world, this means that tree roots are more likely to grow into the mineral layer of the soil, breaking down rock which will eventually combine with carbon dioxide.

This process, called weathering, draws carbon dioxide out of the atmosphere and cools the planet.

The theory suggests that mountainous ecosystems have acted like the Earth’s thermostat, addressing the risk of ‘catastrophic‘ overheating or cooling over millions of years.

In their research paper, published online in Geophysical Research Letters, the researchers carried out studies in tropical rain forests in Peru.

They measured growth of the tree roots across different sites of varying altitude – from the warm Amazonian Lowlands to the cooler mountain ranges of the Andes- every three months over several years.

At each of the sites, they also measured the thickness of the organic layer above the soil.

This information was then combined with data of monthly temperature, humidity, rainfall, and soil moisture to calculate the likely breakdown process of the basalt and granite rocks found in the mountain ranges of Peru.

Using this model, scientists were able to scale up their results to calculate the likely contribution of mountain forests worldwide to global weathering rates.

The researchers then calculated the likely amount of carbon to be pulled out of the atmosphere through weathering when the Earth became very hot.

They looked at the volcanic eruptions in India 65 million years ago, known as the Deccan traps.

The model also allowed them to calculate the weathering process and carbon feedback after the Earth’s cooling 45 million years ago, when great mountain ranges like the Andes and the Himalayas were first formed.

The paper suggests that mountainous regions may play a particularly important role in drawing carbon out of the atmosphere because they have abundant volcanic rock which is highly reactive to weathering when it disintegrates.

This is a simple process driven by tree root growth and the decomposition of organic material,” said lead researcher Chris Doughty, from Oxford University.

Yet it may contribute to Earth’s long-term climate stability. It seems to act like a thermostat, drawing more carbon dioxide out of the atmosphere when it is warm and less when it is cooler.

A series of climatic events over the last 65 million years ago have resulted in global temperatures rising and falling.

However, the weathering process that regulates carbon dioxide in the atmosphere may be buffered by forests that grow in mountainous parts of the world.

In the past, this natural process may have prevented the planet from reaching temperatures that are catastrophic for life.

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How Climate Change Is Increasing Forest Fires Around The World

WILD FIRE

Have wildfires increased globally over recent years? And if so, is global warming to blame?

Research has illuminated this, along with what wildfires do to us and our environment, and which areas are most vulnerable.

Unusually large wildfires ravaged Alaska and Indonesia in 2015. The following year, Canada, California and Spain were devastated by uncontrolled flames.




In 2017, massive fires devastated regions of Chile and now, a deadly blaze in Portugal has claimed dozens of lives.

Science suggests that over the past few decades, the number of wildfires has indeed increased, especially in the western United States.

According to the Union of Concerned Scientists (UCS), every state in the western US has experienced an increase in the average annual number of large wildfires over past decades.

Extensive studies have found that large forest fires in the western US have been occurring nearly five times more often since the 1970s and 80s. Such fires are burning more than six times the land area as before, and lasting almost five times longer.

WILD FIRE

What’s more, wildfire season – meaning seasons with higher wildfire potential – has universally become longer over the past 40 years.

This trend is something Jason Funk, senior climate scientist with UCS, is very worried about.

According to Funk, not only US forests are endangered by increasing wildfires – the trend has been that wildfires are burning more area around the world.

Projections by the UCS suggest that wildfires could get four, five and even six times as bad as they currently are within this century.

WILD FIRE

Funk has been researching the impact of climate change on landscapes in the US, and says there is very well documented scientific evidence that climate change has been increasing the length of the fire season, the size of the area burned each year and the number of wildfires.

Wildfires are typically either started accidentally by humans – such as a burning cigarette carelessly tossed out of a window – or by natural causes like lightning.

These “ignition events” don’t have a major effect on the scale of the fire, says Funk. But what does affect scale are prevailing climate conditions. And these have become warmer and drier – due to climate change.

WILD FIRE

Greenhouse gas emissions, via the greenhouse effect, are causing the global temperature to increase and the climate to change. This enhances the likelihood of wildfires.

Why? Because warmer temperatures increase evaporation, which means the atmosphere draws more moisture from soils, making the land drier.

A warmer climate also leads to earlier snowmelt, which causes soils to be drier for longer. And dry soils become more susceptible to fire.

WILD FIRE

Drier conditions and higher temperatures increase not only the likelihood of a wildfire to occur, but also the duration and the severity of the wildfire.

That means when wildfires break out, they expand faster and burn more area as they move in unpredictable ways. “They really take off and get out of control more frequently than in the past,” said Funk.

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NASA Is Hiring A Planetary Protection Officer To Protect Earth From Alien Harm

earth

Want to save planet Earth? You could apply for NASA’s Planetary Protection Officer role.

The National Aeronautics and Space Administration is currently looking for someone with a secret security clearance to ensure alien life, or “organic-constituent and biological contamination” doesn’t make it’s way back in a space ship.




More than that, this person is “responsible for the leadership of NASA’s planetary protection capability, maintenance of planetary protection policies, and oversight of their implementation by NASAs space flight missions,” according to the job listing.

alien

Candidates must have “advanced knowledge of Planetary Protection,” experience overseeing nationally significant space programs and have demonstrated “skills in diplomacy that resulted in win-win solutions during extremely difficult and complex multilateral discussion.” After all, protecting the planet is sure to present challenges.

Requirements include frequent travel. Could business trips include intergalactic travel? That’s a lot of responsibility for one person, which is why the job comes with a six-figure pay: $124,406 to $187,000 annually.

Thanks for keeping us safe, NASA.

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Astronomers Discover The Biggest Object in The Universe So Far

universe

Astronomers have recently announced the discovery of the BOSS Great Wall, a group of superclusters that span roughly 1 billion light-years across and represents the largest structure ever found in space.

The BOSS Great Wall, which sounds aptly named for its size but actually stands for the Baryon Oscillation Spectroscopic Survey, is a string of superclusters connected by gases lying roughly 4.5 to 6.5 billion light-years away from Earth.




Thanks to gravity, these superclusters stay connected and swirl together through the void of space. The megastructure discovered by a team from the Canary Islands Institute of Astrophysics is composed of 830 separate galaxies and has a mass 10,000 times greater than the Milky Way.

To put the scale of this structure into perspective, we orbit one single star, the Sun. Our galaxy, the Milky Way, has over 200 billion stars, just like our Sun, in it alone with an unknown amount of planets orbiting them.

galaxy

Now, multiply that insane thought by 10,000 and you have the BOSS Great Wall. To our limited scope, it is effectively infinite.

However, not everyone agrees that the super structure should even be considered a structure at all. The argument is that these superclusters are not actually connected.

galaxy

Instead, they have dips and gaps between them that are sort of linked by clouds of gas and dust. This loose connection causes a debate every time ‘great wall-like’ structures are found.

In the end, the arguments seem to boil down to personal definitions of what constitutes a single structure with most researchers agreeing that they are one.

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Pass it on: New Scientist