Selasa, 30 April 2019

Astronomers witness 'one of the most extraordinary black hole systems' - CNN

The black hole, known as V404 Cygni, doesn't behave like others. The jets shoot out possibly within minutes of each other and in all different directions. And while the researchers admit that black holes are some of the most extreme objects in the universe, this one is different.
"This is one of the most extraordinary black hole systems I've ever come across," study author James Miller-Jones said in a statement. Miller-Jones is also an associate professor at Curtin University's International Centre for Radio Astronomy Research.
The study published Monday in the journal Nature.
This is the first photo of a black hole
"Like many black holes, it's feeding on a nearby star, pulling gas away from the star and forming a disk of material that encircles the black hole and spirals towards it under gravity," he said. "What's different in V404 Cygni is that we think the disk of material and the black hole are misaligned. This appears to be causing the inner part of the disk to wobble like a spinning top and fire jets out in different directions as it changes orientation."
The black hole was first discovered in 1989 because it released jets and radiation. Previous outbursts associated with this black hole were noted in 1938 and 1956 and found on archival photographic plates.
V404 Cygni caught the attention of astronomers around the world when it unleashed another bright outburst that lasted for two weeks in 2015. Telescopes everywhere trained on the event, which led to a wealth of observational data.
Normally, jets shoot out from the poles of black holes. These jets were firing off in different directions at different rates over a couple of hours.
Astronomers have found the fastest-growing black hole ever seen, and it's got a monster appetite
The black hole itself is rotating and the gravitational pull is so strong, it's actually pulling nearby space and time around with it. This is called frame-dragging.
The material in the jets is blasted out from the black hole's rotating accretion disk. The disk forms when material from a nearby star is pulled into a circle around the black hole.
For scale, the black hole is nine times more massive than our sun and V404 Cygni's disk is 10 million kilometers across. The jets shoot out material at 60% of the speed of light.
Because the spin axis of the black hole is misaligned, frame-dragging also warps part of the disk, causing an intense wobbling that is responsible for the jets shooting off in different directions.
These are the first massive black holes from the early universe
"This is the only mechanism we can think of that can explain the rapid precession we see in V404 Cygni," Miller-Jones said. "You can think of it like the wobble of a spinning top as it slows down, only in this case, the wobble is caused by Einstein's general theory of relativity."
The researchers had to use a different technique to capture what was happening in the black hole. Normally, they use long exposures.
"These jets were changing so fast that in a four-hour image we saw just a blur," said Alex Tetarenko in a statement, another of the study authors and East Asian Observatory Fellow.
Instead, 70-second-long individual exposures were combined to make a film of the action the astronomers were witnessing.
"We were gobsmacked by what we saw in this system — it was completely unexpected," said Greg Sivakoff in a statement, study author and associate professor at the University of Alberta's department of physics. "Finding this astronomical first has deepened our understanding of how black holes and galaxy formation can work. It tells us a little more about that big question: 'How did we get here?'"

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https://www.cnn.com/2019/04/30/world/spinning-black-hole-jets-scn/index.html

2019-04-30 17:20:00Z
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NASA Eyes Space Station Power Glitch Ahead of SpaceX Dragon Launch - Space.com

NASA engineers are troubleshooting a power glitch on the International Space Station that might affect plans for a SpaceX Dragon capsule's cargo delivery mission this week.

The power issue isn't a concern for the six astronauts currently living and working onboard the space station, according to a NASA statement released yesterday (April 29). But it has affected the Canadarm2 robotic arm, which worries NASA when the agency looks ahead to the scheduled SpaceX Dragon launch tomorrow (May 1).

NASA spokesperson Dan Huot told Space.com the power issue has affected one of two power systems on the station's robotic arm, leaving it without a backup. The Canadarm2 robot arm is vital to SpaceX's Dragon mission, since astronauts will use the appendage to capture Dragon when it arrives at the orbiting lab.

Related: How SpaceX's Dragon Space Capsule Works (Infographic)

A pair of astronauts worked on the robotic arm's power supply during a spacewalk conducted earlier this month, but that work focused on jumper cables along the arm's length. The current problem, instead, is with the station equivalent of a circuit-breaker, basically.

"An issue is being worked with a Main Bus Switching Unit (MBSU) that distributes electrical power to two of the eight power channels on the station," NASA officials said in the statement released yesterday. "Flight controllers have been working to route power through the remaining six power channels."

The launch currently scheduled for early tomorrow morning has already been hit by two delays, which pushed the launch first from April 26 to April 30 on account of "station and orbital mechanics constraints," then to May 1. The rocket will lift off from Space Launch Complex 40 at Cape Canaveral Air Force Station in Florida.

When it does launch, the capsule will set off on a leisurely three-day journey to the space station, where astronauts will unpack the more than 5,550 lbs. (2,495 kilograms) of supplies it carried. That includes fresh supplies and new science experiments.

Space.com managing editor Tariq Malik contributed to this report.

Email Meghan Bartels at mbartels@space.com or follow her @meghanbartels. Follow us on Twitter @Spacedotcom and on Facebook.

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2019-04-30 13:48:00Z
CBMiQmh0dHBzOi8vd3d3LnNwYWNlLmNvbS9zcGFjZXgtZHJhZ29uLW5hc2Etc3RhdGlvbi1wb3dlci1nbGl0Y2guaHRtbNIBRmh0dHBzOi8vd3d3LnNwYWNlLmNvbS9hbXAvc3BhY2V4LWRyYWdvbi1uYXNhLXN0YXRpb24tcG93ZXItZ2xpdGNoLmh0bWw

NASA chief warns asteroid threat is real: ‘It’s about protecting the only planet we know to host life' - Fox News

NASA Administrator Jim Bridenstine is sounding the alarm that an asteroid strike is not something to be taken lightly and is perhaps Earth's biggest threat.

Speaking at the International Academy of Astronautics' 2019 Planetary Defense Conference in College Park, Md., on Monday, Bridenstine said the space agency and other asteroid scientists need to make sure people understand that the threat is very real and not just the imagination of big-budget blockbuster movie directors.

"We have to make sure that people understand that this is not about Hollywood, it's not about movies," Bridenstine said at the conference, according to Space.com. "This is about ultimately protecting the only planet we know right now to host life, and that is the planet Earth."

NASA GAMEPLANS MASSIVE ASTEROID STRIKE

"We know for a fact that the dinosaurs did not have a space program. But we do, and we need to use it," Bridenstine added, attempting to portray planetary defense on the same level as a return trip to the Moon. The Trump administration wants to see astronauts return to the Moon by 2024, with or without the help of NASA.

NASA Administrator Jim Bridenstine testifies before the House Committee on Science, Space and Technology on April 2, 2019, during a hearing to review NASA's fiscal year 2020 budget request.

NASA Administrator Jim Bridenstine testifies before the House Committee on Science, Space and Technology on April 2, 2019, during a hearing to review NASA's fiscal year 2020 budget request.

Bridenstine knows the perils of asteroid strikes all too well. In February 2013, he had been a Congressman in Oklahoma for just a month when a devastating asteroid streaked across the Russian sky.

Known as the Chelyabinsk Event, it was the largest known meteor strike in over a century and it injured more than 1,600 people. It "released the energy equivalent of around 440,000 tons of TNT," according to NASA.

"I wish I could tell you these events are exceptionally unique," Bridenstine said during the presentation, noting they have occurred three times in the past 100 years. "But they are not."

Currently, there are two asteroid-centric missions going on around the world —  NASA's OSIRIS-REx probe, which reached the Bennu asteroid in December 2018, and the Japanese Hayabusa2 spacecraft, which recently "bombed" the Ryugu asteroid in an effort to learn more about it.

HOW AMERICA CAN GET ITS SLICE OF THE $1 TRILLION SPACE ECONOMY

Bridenstine highlighted the scientific importance of both of these missions but added that planetary defense is also an important component. "Yes, it's about science, it's about discovery, it's about exploration, but one of the reasons we do those missions is so that we can characterize those objects to protect, again, the only planet we know to host life."

"We have to use our systems, use our capabilities to ultimately get a lot more data, and we have to do it faster," Bridenstine said.

Planetary defense

When it comes to planetary defense, NASA is not sitting on its haunches, having taken several steps to protect Earth by detecting and tracking near-Earth Objects, also known as NEOs.

Last June, NASA unveiled a 20-page plan that details steps the U.S. should take to be better prepared for NEOs, asteroids and comets that come within 30 million miles of Earth. Lindley Johnson, the space agency's planetary defense officer, said at the time that the country "already has significant scientific, technical and operational capabilities" to help with NEOs, but implementing the new plan would "greatly increase our nation’s readiness and work with international partners to effectively respond should a new potential asteroid impact be detected.”

There are approximately 18,000 known NEOs and that number is constantly growing.

MYSTERIOUS INTERSTELLAR METEOR MAY HAVE SLAMMED INTO EARTH IN 2014

In 2016, NASA formalized the agency’s prior program for detecting and tracking NEOs and put it inside its Science Mission Directorate.

NASA will launch its first asteroid defense mission, the Double Asteroid Redirection Test (DART) mission, in 2022. Earlier this month, NASA awarded a $69 million contract to SpaceX, the space exploration company led by Elon Musk, to help with DART.

Currently, asteroid scientists from around the world are conducting a drill showing what the various global agencies would do about a potential asteroid collision. For the first time, the drill is being played out over social media. Updates of the hypothetical event are being shared on the ESA Operations Twitter account until May 3.

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2019-04-30 13:28:01Z
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What if an asteroid was about to hit Earth? Scientists ponder question - Phys.org

A Nasamosaic image of asteroid Bennu, composed of 12 PolyCam images
A Nasamosaic image of asteroid Bennu, composed of 12 PolyCam images

Here's a hypothetical: a telescope detects an asteroid between 100 and 300 meters in diameter racing through our solar system at 14 kilometers per second, 57 million kilometers from Earth.

Astronomers estimate a one percent risk the will collide with our planet on April 27, 2027. What should we do?

It's this potentially catastrophic scenario that 300 astronomers, scientists, engineers and emergency experts are applying their collective minds to this week in a Washington suburb, the fourth such international effort since 2013.

"We have to make sure people understand this is not about Hollywood," said NASA Administrator Jim Bridenstine as he opened the sixth International Planetary Defense Conference at the University of Maryland's campus in College Park.

Countries represented include China, France, Germany, Israel, Italy, Russia and the United States.

The idea that the planet Earth may one day have to defend itself against an asteroid used to elicit what experts call a "giggle factor."

But a meteor that blew up in the atmosphere over Russia on February 15, 2013, helped put an end to the sneers.

On that morning, a 65-foot (20-meter) asteroid appear out of nowhere over the southern Urals, exploding 14 miles (23 kilometers) above the town of Chelyabinsk with such force that it shattered the windows of thousands of buildings.

A thousand people were injured by the shards.

But "the positive aspect of Chelyabinsk is that it made the public aware, it made the political decision makers aware," Detlef Koschny, co-manager of the Planetary Defence Office of the European Space Agency (ESA) told AFP.

A meteorite trail is seen above a residential apartment block in the Urals city of Chelyabinsk, on February 15, 2013
A meteorite trail is seen above a residential apartment block in the Urals city of Chelyabinsk, on February 15, 2013

How many?

Only those asteroids whose orbit around our Sun brings them within 31 million miles of our planet—defined as "near Earth"—are of interest.

Astronomers are finding new ones each day: more than 700 so far this year, for a total of 20,001, said Lindley Johnson of NASA's Planetary Defense Coordination Office, which was created in 2016.

Among the most risky is a rock named 2000SG344: 165 feet in diameter, with a one in 2,096 chance in striking the Earth within a hundred years, according to the ESA.

The majority are very small, but 942 are more than 0.6 miles across, estimates astronomer Alan Harris.

The scientist told an audience that some large ones are probably still out there: "A fair fraction of the biggest ones are hiding... basically parked behind the Sun."

They are found mainly by two US telescopes, one in Arizona and the other in Hawaii.

The ESA has built a telescope for this purpose in Spain and is planning others in Chile and Sicily.

Many astronomers are demanding a space telescope because terrestrial telescopes are unable to detect objects on the other side of the Sun.

A view of the facade of a local paint and varnish plant damaged by a shockwave from a meteor in the Urals city of Chelyabinsk on
A view of the facade of a local paint and varnish plant damaged by a shockwave from a meteor in the Urals city of Chelyabinsk on February 15, 2013

Deflecting an asteroid

This week's exercise seeks to simulate global response to a catastrophic meteorite. The first step is aiming telescopes at the threat to precisely calculate its speed and trajectory, following rough initial estimates.

Then it boils down to two choices: try to deflect the object, or evacuate.

If it is less than 165 feet, the international consensus is to evacuate the threatened region. According to Koschny, it is possible to predict the country it will strike two weeks ahead. Days away from impact, it can be narrowed down to within hundreds of kilometers.

What about bigger objects? Trying to nuke them to smithereens like in the movie Armageddon would be bad idea, because it could just create smaller but still dangerous pieces.

The plan, instead, is to launch a device toward the asteroid to divert its trajectory—like a cosmic bumper car.

NASA plans to test this idea out on a real asteroid 492 feet across, in 2022, with the Double Asteroid Redirection Test (DART) mission.

One issue that remains is politics, says Romana Kofler, of the United Nations Office for Outer Space Affairs.

"Who would be the decision making authority?" she asked. "The consensus was to leave this aspect out."

The United Nations Security Council would likely be convened, but it's an open question as to whether rich countries would finance an operation if they themselves weren't in the sights of 2000SG344 or another celestial rock.


Explore further

The day the asteroid might hit

© 2019 AFP

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This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.

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2019-04-30 07:15:51Z
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'These events are not rare': NASA exercise highlights existential threat of asteroid impacting Earth - New Zealand Herald

It's the doomsday scenario fit for a Hollywood blockbuster — and NASA scientists are about to see it go down.

This week researchers will run an exercise at the 2019 Planetary Defence Conference that will play out a "realistic scenario" of an asteroid flying through space on an impact trajectory with Earth, reports news.com.au

NASA's Planetary Defence Co-ordination Office (PDCO) is running the simulation exercise as part of a recently announced federal "action plan" for defending our planet against asteroid impact.

The hypothetical asteroid is thought to be about 100 to 300 metres in size and only has a very small likelihood of smashing into Earth on April 29, 2027, according to a NASA web page dedicated to the highly detailed scenario.

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Global astronomers are always on the lookout for near-Earth objects (NEOs), which are classified as asteroids and comets that orbit the Sun and come within 50 million kilometres of Earth's orbit.

Along with the NASA unit, the European Space Agency's Space Situational Awareness-NEO Segment and the International Asteroid Warning Network (IAWN) are tasked with hunting the skies for potentially dangerous space rocks.

These "tabletop exercises" are not uncommon and are about walking through the steps that will need to be taken along with governments and emergency agencies to mitigate the risk to society should the unthinkable happen.

"These exercises have really helped us in the planetary defence community to understand what our colleagues on the disaster management side need to know," said Lindley Johnson, NASA's planetary defence officer. "This exercise will help us develop more effective communications with each other and with our governments."

NASA has been tasked with the goal of identifying and tracking 90 per cent of near-Earth meteors that are larger than 140 metres by the year 2020. But the task could end up taking nearly three decades, experts claim. And even then we're far from protected.


Last month, it was revealed a relatively small and undetected meteor blew up over the Bering Sea, off Russia's Kamchatka Peninsula on December 18. The explosion — which happened 25.6 kilometres above the Earth's surface — released 10 times the energy produced by the atomic bomb dropped on Hiroshima in World War II.

Six years ago, a meteor exploded over the Russian city of Chelyabinsk and released a shockwave that shattered thousands of windows and injured more than 1600 people. That meteor was only 19 metres wide.

A meteor streaks through the sky over Chelyabinsk, Russia, in 2013. Photo / AP
A meteor streaks through the sky over Chelyabinsk, Russia, in 2013. Photo / AP

"The thing is the one over Chelyabinsk and this latest one (in December) are about 10 times smaller" that the ones targeted by the NASA mandate, astronomer Alan Duffy explained to news.com.au last month. "It's far harder to detect those, and we still haven't found all the larger asteroids yet."

He has called for more funding to be allocated to monitoring systems, asserting "it is just a matter of time before one of these blasts occur over a city and cause incredible damage".

During a keynote address at the opening of the Planetary Defence Conference, NASA administrator Jim Bridenstine warned preparing for an asteroid impact is something that needs to be taken very seriously.

"We have to make sure that people understand that this is not about Hollywood, it's not about movies. This is about ultimately protecting the only planet we know, right now, to host life, and that is the planet Earth," he said.
"These events are not rare, they happen."

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https://www.nzherald.co.nz/world/news/article.cfm?c_id=2&objectid=12226623

2019-04-30 06:24:32Z
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Senin, 29 April 2019

What if a killer asteroid were headed toward Earth? NASA plans to find out this week - NBC News

By David Freeman

Think of it as a crash course in averting asteroid crashes.

As part of the 2019 Planetary Defense Conference, NASA, the Federal Emergency Management Agency and their international partners will conduct a so-called tabletop exercise designed to show how they would react to the discovery of a fictional asteroid heading our way.

The exercise is being conducted as part of a federal "action plan" for defending Earth against asteroids that was announced last June. It will play out over the five days of the conference, which begins in College Park, Maryland, on Monday and runs through May 3. You can watch it live in the player below.

"Exercises like this have been run at several conferences over the years, and government agencies have also ​had them," Andrew Rivkin, a planetary astronomer at Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland, and an expert on asteroids, told NBC News MACH in an email. "It's definitely worth doing, if only so people are aware of the issues and how complex some of them are."

Rivkin, who said he was participating in the exercise, likened it to a fire drill but added that the consequences of a major asteroid strike "could be very bad (just ask the dinosaurs)," referring to the impact of a six-mile-wide asteroid that is believed to have caused the dinosaurs' demise some 65 million years ago.

According to the loosely scripted scenario, astronomers discover that a make-believe space rock dubbed 2019 PDC has a one-in-100 chance of smashing into Earth in 2027. Participants in the exercise, including the European Space Agency and the International Asteroid Warning Network, as well as NASA and FEMA, will consider how they might mount space missions to investigate and possibly deflect the asteroid — and how the effects of an impact might be mitigated.

Even though 2019 PDC is fictitious, the threat posed by asteroid strikes is all too real. As of the start of 2019, more than 19,000 near-Earth objects (NEOs) had been discovered — and 30 more are discovered each week as astronomers continue to search for them.

"We've only found about one-third of NEOs large enough to cause severe regional damage, so we have a lot of work left to do," Amy Mainzer, an astronomer and asteroid expert at NASA's Jet Propulsion Laboratory in Pasadena, California, said in an email. "We need to build and operate more capable space- and ground-based telescopes, in my opinion," she added.

The animation depicts a mapping of the positions of known near-Earth objects (NEOs) at points in time over the past 20 years. There are more than 18,000 known NEOs, with new ones being discovered at the rate of about 40 per week.NASA/JPL-Caltech

So far, experts haven't identified any large objects on a collision course with Earth.

"We are confident that searches have found anything big enough to be a worldwide problem," Rivkin said in the email. "The space agencies of the world are working together to complete the search programs to make sure the neighborhood is safe, and NASA is planning a mission called DART [for Double Asteroid Redirection Test] to practice deflecting an asteroid just in case we ever need to do so. We don't anticipate having to do so any time in the foreseeable future, but it's good to be prepared!"

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2019-04-29 16:00:00Z
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Weird Black Hole Is Shooting Out Wobbly Jets Because It's Dragging Spacetime - ScienceAlert

Some 7,800 light-years away, in the constellation of Cygnus, lies a most peculiar black hole. It's called V404 Cygni, and in 2015, telescopes around the world stared in wonder as it woke from dormancy to devour material from a star over the course of a week.

That one event provided such a wealth of information that astronomers are still analysing it. And they have just discovered an amazing occurrence: relativistic jets wobbling so fast their change in direction can be seen in mere minutes.

And, as they do so, they puff out high-speed clouds of plasma.

"This is one of the most extraordinary black hole systems I've ever come across," said astrophysicist James Miller-Jones of the International Centre for Radio Astronomy Research (ICRAR) at Curtin University in Australia.

V404 Cygni is a binary microquasar system consisting of a black hole about nine times the mass of the Sun and a companion star, an early red giant slightly smaller than the Sun.

The black hole is slowly devouring the red giant; the material siphoned away from the star is orbiting the black hole in the form of an accretion disc, a bit like water circling a drain. The closest regions of the disc are incredibly dense and hot, and extremely radiant; and, as the black hole feeds, it shoots out powerful jets of plasma, presumably from its poles.

Scientists don't know the precise mechanism behind jet production. They think material from the innermost rim of the accretion disc is funnelled along the black hole's magnetic field lines, which act as a synchrotron to accelerate the particles before launching them at tremendous velocities.

But V404 Cygni's wobbly jets, shooting out in different directions at different times, on such rapidly changing timescales, and at velocities up to 60 percent of the speed of light, are in a class of their own.

"We think the disc of material and the black hole are misaligned," Miller-Jones said. "This appears to be causing the inner part of the disc to wobble like a spinning top and fire jets out in different directions as it changes orientation."

It's a bit like a spinning top that starts to wobble as it's slowing down, the researchers said. This change in the rotational axis of a spinning body is called precession. In this particular instance, we have a handy explanation for it courtesy of Albert Einstein.

In his theory of general relativity, Einstein predicted an effect called frame-dragging. As it spins, a rotating black hole's gravitational field is so intense that it essentially drags spacetime with it. (This is one of the effects scientists hoped to observe when they took a picture of Pōwehi.)

In the case of V404 Cygni, the accretion disc is about 10 million kilometres (6.2 million miles) across. The misalignment of the black hole's rotational axis with the accretion disc has warped the inner few thousand kilometres of said disc.

The frame-dragging effect then pulls the warped part of the disc along with the black hole's rotation, which sends the jet careening off in all directions. In addition, that inner section of the accretion disc is puffed up like a solid doughnut that also precesses.

"This is the only mechanism we can think of that can explain the rapid precession we see in V404 Cygni," Miller-Jones said.

It's so fast that the usual method radio telescopes use for imaging space were practically useless. Usually, these devices rely on long exposures, observing a region for several hours at a time, moving across the sky to track their target. But in this case, the method produced images too blurred to be of use.

So the team had to use a different method, taking 103 separate images with exposure times of just 70 seconds and stitching them together to create a movie - and sure enough, there were the wibbly wobbly spacetimey jets.

"We were gobsmacked by what we saw in this system - it was completely unexpected," said physicist Greg Sivakoff of the University of Alberta.

"Finding this astronomical first has deepened our understanding of how black holes and galaxy formation can work. It tells us a little more about that big question: 'How did we get here?'"

The research has been published in Nature.

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https://www.sciencealert.com/extraordinary-black-hole-shoots-out-wobbling-jets-as-it-devours-a-star

2019-04-29 15:18:21Z
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Scientists find ‘alien’ grain of dust in Antarctica that could challenge our understanding of the solar system - The Independent

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Scientists find ‘alien’ grain of dust in Antarctica that could challenge our understanding of the solar system  The Independent

A tiny, "alien" grain of dust that was created as a long-gone star died has been found by scientists. The tiny speck of stardust was found inside of a chondritic ...


https://www.independent.co.uk/life-style/gadgets-and-tech/news/alien-grain-of-dust-antarctica-solar-system-life-a8891486.html

2019-04-29 15:00:48Z
CAIiEC0uISdWkkk595TLCRQ3wFAqFwgEKg4IACoGCAowzdp7ML-3CTCRx_0F

Asteroid collision impact drill set for this week - Fox News

World governments have been concerned for decades about a potential asteroid collision and the chaos that would ensue upon Earth. Now, the actions of what agencies around the world would do about it are being shared with the public for the first time ever on social media.

Though the drill is run every two years by asteroid scientists around the world, the European Space Agency has decided to share the event publicly so everyone can see what would happen and what actions might be taken to mitigate the damage.

“The first step in protecting our planet is knowing what’s out there,” says Rüdiger Jehn, ESA’s Head of Planetary Defense, in a statement. “Only then, with enough warning, can we take the steps needed to prevent an asteroid strike altogether, or to minimize the damage it does on the ground.”

Graphic showing the hypothetical impact risk corrdior of asteroid 2019 PDC, when its orbit is still not fully known. (Credit: Google Earth, ESA)

Graphic showing the hypothetical impact risk corrdior of asteroid 2019 PDC, when its orbit is still not fully known. (Credit: Google Earth, ESA)

ELON MUSK IS GOING TO HELP NASA SAVE EARTH FROM AN ASTEROID COLLISION

Updates from the drill will be shared on the ESA Operations Twitter account, starting Monday, April 29 and running until May 3.

The first tweet has already been written, with the ESA writing: "A hypothetical asteroid has been 'discovered', and worryingly looks set to impact Earth. Follow the progress of fictional asteroid #2019PDC and the response on the ground, over the next few days of the #PlanetaryDefense Conference. #FictionalEvent🌍☄️"

The asteroid scientists who take part in the drill are doing so as part of the 2019 Planetary Defense Conference, which is put on by NASA's Planetary Defense Coordination Office and the U.S. Federal Emergency Management Agency. The scientists will be assigned different roles, such as "space agency," "astronomer" or "national government," and will work off what each other is doing, the ESA added in the statement.

In 2016, NASA formalized the agency’s prior program for detecting and tracking near-Earth Objects (NEOs) and put it inside its Science Mission Directorate.

Though there are 20,000 asteroids (and counting) whose orbit brings them near Earth, NASA has been expanding its protocols for how to take action from a potential collision.

HOW AMERICA CAN GET ITS SLICE OF THE $1 TRILLION SPACE ECONOMY

Last June, NASA unveiled a 20-page plan that details steps the U.S. should take to be better prepared for NEOs such as asteroids and comets that come within 30 million miles of the planet.

Lindley Johnson, the space agency's planetary defense officer, said at the time that the country "already has significant scientific, technical and operational capabilities" to help with NEOs, but implementing the new plan would "greatly increase our nation’s readiness and work with international partners to effectively respond should a new potential asteroid impact be detected.”

In addition to enhancing NEO detection, tracking and characterizing capabilities and improving modeling prediction, the plan also aims to develop technologies for deflecting NEOs, increasing international cooperation and establishing new NEO impact emergency procedures and action protocols.

ANCIENT ASTEROID STRIKES ON MARS MAY HAVE 'PRODUCED KEY INGREDIENTS FOR LIFE'

Earlier this month, NASA awarded a $69 million contract to SpaceX, the space exploration company led by Elon Musk, to help it with asteroid deflection via its Double Asteroid Redirection Test (DART) mission.

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2019-04-29 13:43:32Z
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SpaceX readies for early morning launch Wednesday at Cape Canaveral - WFTV Orlando

CAPE CANAVERAL, Fla. - SpaceX is planning to launch thousands of pounds of supplies, research equipment and hardware to the International Space Station early Wednesday.

The launch announcement comes after SpaceX completed a static fire test of its Falcon 9 rocket on Saturday.

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The rocket is set to blast off at Space Launch Complex 40 at Cape Canaveral Air Force Station at 3:59 a.m.


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This launch will mark SpaceX’s 17th mission under NASA's Commercial Resupply Services contract to send cargo to the International Space Station.

WFTV will share coverage of the launch if it happens on Wednesday on Eyewitness News This Morning.


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https://www.wftv.com/news/local/spacex-readies-for-early-morning-launch-wednesday-at-cape-canaveral/944319165

2019-04-28 22:41:15Z
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Minggu, 28 April 2019

The day the asteroid might hit - EarthSky

Line drawing of asteroid orbit in the inner solar system.

Hypothetical orbit for fictional asteroid 2019 PDC, via ESA.

The European Space Agency (ESA) said late last week it’ll be tweeting coverage of a major international asteroid impact exercise live via social media from April 29 to May 3, 2019. You can follow the coverage via the @esaoperations Twitter channel. It’s a drill – much like the tornado drills some of us underwent in elementary school – but in this case conducted by scientists, space agencies and civil protection organizations, all acting as if an asteroid is headed for an impact with Earth. This exercise – simulating a fictional, but plausible, imminent asteroid impact – is conducted every two years by asteroid experts across the globe. It’s being conducted from the Planetary Defense Conference in Washington, D.C. ESA said:

During the week-long scenario, participants – playing roles such as ‘national government’, ‘space agency’, ‘astronomer’ and ‘civil protection office’ – don’t know how the situation will evolve from one day to the next, and must make plans based on the daily updates they are given.

Follow the live coverage April 29 to May 3 via @esaoperations on Twitter

You can also participate, in a more limited way, via ESA’s Facebook page. It will host two livestream videos straight from the Planetary Defense Conference. The first will be today (Sunday, April 28) at 12 UTC (14 CEST, 8 a.m. EDT; translate UTC to your time) with Rüdiger Jehn, ESA’s Head of Planetary Defense. The second will be Thursday, May 2, at around mid-afternoon European time.

Check out livestream videos from the Planetary Defense Conference via ESA’s Facebook page

For daily updates on the asteroid impact scenario, check out “Rolling coverage: Brace for hypothetical asteroid impact,” beginning on the first day of the conference, Monday, April 29.

Follow ESA’s rolling coverage: Daily updates on the asteroid impact scenario.

This year’s hypothetical asteroid has been given the label ‘2019 PDC’. NOTE: Although realistic, all “objects” and “events” described below are completely fictional and do NOT describe an actual asteroid impact. ESA described the fictional scenario this way:

— An asteroid was discovered on March 26 2019, and has been given the name 2019 PDC by the International Astronomical Union‘s (IAU) Minor Planet Center.

— Initial calculations suggest the orbit of 2019 PDC will bring it within 7.5 million km [4.6 million miles] of Earth’s orbit. (Or, within 0.05 AU of Earth’s orbit).

.— 2019 PDC is travelling in an eccentric orbit, extending 2.94 AU at its farthest point from the sun (in the middle of the main asteroid belt), and 0.94 AU at its closest. It completes one full orbit around the sun every 971 days (2.66 years). See its orbit in more detail here.

— The day after 2019 PDC is discovered, ESA and NASA’s impact monitoring systems identify several future dates when the asteroid could hit Earth. Both systems agree that the asteroid is most likely to strike on April 29, 2027 – more than eight years away – with a very low probability of impact of about 1 in 50,000.

— When it was first detected, asteroid 2019 PDC was about 57 million km [35.4 million miles] from Earth, equal to 0.38 astronomical units [0.38 of the average Earth-sun distance]. It was travelling about 14 km/s [8.7 miles/sec], and slowly getting brighter.

— As observations continue, the likelihood of an impact in 2027 increases. Three weeks after discovery, after observations were paused during the full moon (and reduced visibility), the chance of impact has risen to 0.4 percent – that’s a chance of 1 in 250.

Google Earth image of Earth, with a red line shown across the middle of the U.S.: the 'risk corridor.'

View larger. | Graphic showing the hypothetical impact risk corridor of hypothetical asteroid 2019 PDC, when its orbit is still not fully known. ESA said: “The asteroid’s uncertainty region at the time of the potential impact is much longer than the diameter of the Earth, but its width is only about 70 kilometers (45 miles). The intersection of the uncertainty region with the Earth creates a so-called ‘risk corridor’ across the surface of the Earth. The corridor wraps more than halfway around the globe, spanning from Hawaii on the western end, across the U.S. and Atlantic Ocean, and all the way to central and southern Africa on the eastern end. The red dots on the Google Earth image trace the risk corridor.” Image via ESA.

— Very little is known about the asteroid’s physical properties. From its brightness, experts determine that the asteroid’s mean size could be anywhere from 100-300 meters [approximately 300 to 1,000 feet].

— Asteroid 2019 PDC continued to approach Earth for more than a month after discovery, reaching its closest point on May 13. Unfortunately, the asteroid was too far away to be detected, and it is not expected to pass close to Earth until 2027 – the year of impact.

— As astronomers continued to track 2019 PDC, the chance of impact continued to rise. By April 2019, the first day of the Planetary Defence Conference, the probability of impact will have risen to 1 in 100.

This exercise is being produced by experts from NASA’s Planetary Defense Coordination Office working together with the U.S. Federal Emergency Management Agency (FEMA) at the 2019 Planetary Defense Conference, Washington, D.C. The conference is strongly supported by ESA, NASA and other agencies, organizations and scientific institutions.

Follow the live tweets April 29 to May 3 via @esaoperations on Twitter

Check out livestream videos from the Planetary Defense Conference via ESA’s Facebook page

Follow ESA’s rolling coverage: Daily updates on the asteroid impact scenario.

Read more from ESA: The day the asteroid might hit

Bottom line: At the Planetary Defense Conference in Washington, D.C. – April 29 to May 3, 2019 – scientists, space agencies and civil protection organizations will be acting as if an asteroid is headed for an impact with Earth. This exercise – simulating a fictional but plausible imminent asteroid impact – is conducted every two years by these asteroid experts. This story tells how to follow the exercise on social media.

Deborah Byrd

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https://earthsky.org/human-world/esa-social-media-hypothetical-impact-scenario-pdc

2019-04-28 13:13:00Z
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SpaceX Delays Next Dragon Cargo Launch to May 1 - Space.com

SpaceX has pushed back the launch of a Dragon cargo mission for NASA this week by 24 hours, with liftoff now targeted for Wednesday (May 1). 

The uncrewed Dragon resupply ship will now launch to the International Space Station Wednesday at 3:59 a.m. EDT (0759 GMT) from Space Launch Complex 40 at Cape Canaveral Air Force Station in Florida, according to SpaceX and NASA. SpaceX test-fired the Falcon 9 rocket that will launch the mission on Saturday (April 27). 

"Static fire test of Falcon 9 complete — targeting May 1 launch from Pad 40 in Florida for Dragon's seventeenth mission to the @Space_Station," SpaceX representatives said in a Twitter update on the mission. 

Related: How SpaceX's Dragon Space Capsule Works (Infographic)

The one-day launch slip follows a four-day delay of the mission (it was initially scheduled to launch April 26) by NASA and SpaceX "due to station and orbital mechanics constraints," NASA officials said at the time. 

SpaceX representatives said the company would use those four extra days for launch vehicle checks and the Falcon 9 static fire test, which fired the booster's first stage engines briefly. Static fire tests are a standard SpaceX activity before every launch.

The upcoming Dragon cargo mission will be SpaceX's 17th delivery flight for NASA. The spacecraft will deliver more than 5,500 lbs. (2,495 kilograms) of fresh supplies, experiment hardware and other gear to the Expedition 59 astronauts currently on the space station.

SpaceX also has a contract to fly astronauts to the station for NASA using the company's new Crew Dragon spacecraft, which made its first uncrewed test flight in March. An in-flight abort system test for Crew Dragon is expected later this year, followed by a crewed test flight by NASA astronauts. 

But before SpaceX can proceed with the in-flight abort test, the company must complete its investigation into an April 20 anomaly during a Crew Dragon abort system test. That anomaly occurred as SpaceX was testing the Crew Dragon's eight SuperDraco abort engines on a test stand at Landing Zone 1, one of the company's two rocket landing pads at Cape Canaveral Air Force Station.

Meanwhile, SpaceX is also gearing up for another big mission: the next launch of its massive Falcon Heavy megarocket

Last week, SpaceX successfully test fired the center core stage of the Falcon Heavy that will be used to launch the Space Test Program-2 mission for the U.S. Air Force. That mission will include a host of different payloads for the U.S. Air Force, NASA, Planetary Society and other customers.

 Email Tariq Malik at tmalik@space.com or follow him @tariqjmalik. Follow us @Spacedotcom and Facebook.  

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https://www.space.com/spacex-dragon-cargo-crs-17-launch-delay.html

2019-04-28 12:35:00Z
52780278599684

Sabtu, 27 April 2019

NASA will simulate an asteroid impact scenario with live tweeting - Mashable

What would happen if an asteroid impacted Earth sorta like a comet did in 1998's 'Deep Impact?"
What would happen if an asteroid impacted Earth sorta like a comet did in 1998's 'Deep Impact?"
Image: Dreamworks/Paramount/Kobal/REX/Shutterstock

If an asteroid were ever to be come hurtling towards Earth, what would be the plan to stop it from impacting the planet?

That's the question NASA and its partners, including the European Space Agency and the U.S.'s Federal Emergency Management Agency (FEMA), are gathering at the 2019 Planetary Defense Conference in early May to investigate.

During the five day conference, NASA and its partners plan to engage in a "tabletop exercise" that simulates what would happen if scientists and authorities were to learn of a near-Earth Object (NEO) impact scenario.

"A tabletop exercise of a simulated emergency commonly used in disaster management planning to help inform involved players of important aspects of a possible disaster and identify issues for accomplishing a successful response," says NASA.

In the exercise (detailed by the ESA here), NASA and its partners have to respond to a "realistic — but fictional — scenario" involving a NEO named "2019 PDC," which has a 1 in 100 chance of impacting Earth in 2027.

Armed with all of the hypothetical information about "2019 PDC," the exercise is intended to see how the various organizations and governments would handle the situation as it unfolds.

"The first step in protecting our planet is knowing what’s out there," said Rüdiger Jehn, the ESA’s Head of Planetary Defence. "Only then, with enough warning, can we take the steps needed to prevent an asteroid strike altogether, or minimize the damage it does on the ground."

In such a situation, the ESA says it would live tweet details "so you’ll find out the ‘news’ as the experts do." And for the hypothetical 2019 PDC asteroid exercise at the conference, the agency will indeed live tweet the series of decided actions as if they are made.

"These exercises have really helped us in the planetary defense community to understand what our colleagues on the disaster management side need to know," said Lindley Johnson, NASA's Planetary Defense Officer. "This exercise will help us develop more effective communications with each other and with our governments."

Despite NASA having participated in six NEO impact exercises before, each scenario is different and the agency says it's learned that the focus is not always on the asteroid details, even though that's still crucial to creating a plan to either deflect it or reduce its impact.

"What emergency managers want to know is when, where and how an asteroid would impact, and the type and extent of damage that could occur," said Leviticus Lewis of the Response Operations Division for FEMA.

Well, you know what they say...it's better to be prepared. At the very least, NASA and friends won't be panicking as hard if an asteroid were ever to really hit Earth.

Uploads%252fvideo uploaders%252fdistribution thumb%252fimage%252f91006%252fbc8be35c 14ed 4e21 9aa4 2e0064c1d0b9.jpg%252foriginal.jpg?signature=eiul1gluktirjpa5mvpdpaxvxjy=&source=https%3a%2f%2fblueprint api production.s3.amazonaws

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https://mashable.com/article/nasa-esa-fema-asteroid-impact-earth-simulation-response/

2019-04-27 17:09:39Z
52780277812415

NASA will simulate an asteroid impact scenario with live tweeting - Mashable

What would happen if an asteroid impacted Earth sorta like a comet did in 1998's 'Deep Impact?"
What would happen if an asteroid impacted Earth sorta like a comet did in 1998's 'Deep Impact?"
Image: Dreamworks/Paramount/Kobal/REX/Shutterstock

If an asteroid were ever to be come hurtling towards Earth, what would be the plan to stop it from impacting the planet?

That's the question NASA and its partners, including the European Space Agency and the U.S.'s Federal Emergency Management Agency (FEMA), are gathering at the 2019 Planetary Defense Conference in early May to investigate.

During the five day conference, NASA and its partners plan to engage in a "tabletop exercise" that simulates what would happen if scientists and authorities were to learn of a near-Earth Object (NEO) impact scenario.

"A tabletop exercise of a simulated emergency commonly used in disaster management planning to help inform involved players of important aspects of a possible disaster and identify issues for accomplishing a successful response," says NASA.

In the exercise (detailed by the ESA here), NASA and its partners have to respond to a "realistic — but fictional — scenario" involving a NEO named "2019 PDC," which has a 1 in 100 chance of impacting Earth in 2027.

Armed with all of the hypothetical information about "2019 PDC," the exercise is intended to see how the various organizations and governments would handle the situation as it unfolds.

"The first step in protecting our planet is knowing what’s out there," said Rüdiger Jehn, the ESA’s Head of Planetary Defence. "Only then, with enough warning, can we take the steps needed to prevent an asteroid strike altogether, or minimize the damage it does on the ground."

In such a situation, the ESA says it would live tweet details "so you’ll find out the ‘news’ as the experts do." And for the hypothetical 2019 PDC asteroid exercise at the conference, the agency will indeed live tweet the series of decided actions as if they are made.

"These exercises have really helped us in the planetary defense community to understand what our colleagues on the disaster management side need to know," said Lindley Johnson, NASA's Planetary Defense Officer. "This exercise will help us develop more effective communications with each other and with our governments."

Despite NASA having participated in six NEO impact exercises before, each scenario is different and the agency says it's learned that the focus is not always on the asteroid details, even though that's still crucial to creating a plan to either deflect it or reduce its impact.

"What emergency managers want to know is when, where and how an asteroid would impact, and the type and extent of damage that could occur," said Leviticus Lewis of the Response Operations Division for FEMA.

Well, you know what they say...it's better to be prepared. At the very least, NASA and friends won't be panicking as hard if an asteroid were ever to really hit Earth.

Uploads%252fvideo uploaders%252fdistribution thumb%252fimage%252f91006%252fbc8be35c 14ed 4e21 9aa4 2e0064c1d0b9.jpg%252foriginal.jpg?signature=eiul1gluktirjpa5mvpdpaxvxjy=&source=https%3a%2f%2fblueprint api production.s3.amazonaws

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https://mashable.com/article/nasa-esa-fema-asteroid-impact-earth-simulation-response/

2019-04-27 17:09:00Z
52780277812415

Important Threshold Crossed in Mystery of the Universe's Expansion Rate - SciTechDaily

Mystery of the Universe’s Expansion Rate Widens

This is a ground-based telescope’s view of the Large Magellanic Cloud, a satellite galaxy of our Milky Way. The inset image, taken by the Hubble Space Telescope, reveals one of many star clusters scattered throughout the dwarf galaxy. The cluster members include a special class of pulsating star called a Cepheid variable, which brightens and dims at a predictable rate that corresponds to its intrinsic brightness. Once astronomers determine that value, they can measure the light from these stars to calculate an accurate distance to the galaxy. When the new Hubble observations are correlated with an independent distance measurement technique to the Large Magellanic Cloud (using straightforward trigonometry), the researchers were able to strengthen the foundation of the so-called “cosmic distance ladder.” This “fine-tuning” has significantly improved the accuracy of the rate at which the universe is expanding, called the Hubble constant. Credits: NASA, ESA, A. Riess (STScI/JHU) and Palomar Digitized Sky Survey

Astronomers using NASA’s Hubble Space Telescope say they have crossed an important threshold in revealing a discrepancy between the two key techniques for measuring the universe’s expansion rate. The recent study strengthens the case that new theories may be needed to explain the forces that have shaped the cosmos.

A brief recap: The universe is getting bigger every second. The space between galaxies is stretching, like dough rising in the oven. But how fast is the universe expanding? As Hubble and other telescopes seek to answer this question, they have run into an intriguing difference between what scientists predict and what they observe.

Hubble measurements suggest a faster expansion rate in the modern universe than expected, based on how the universe appeared more than 13 billion years ago. These measurements of the early universe come from the European Space Agency’s Planck satellite. This discrepancy has been identified in scientific papers over the last several years, but it has been unclear whether differences in measurement techniques are to blame, or whether the difference could result from unlucky measurements.

The latest Hubble data lower the possibility that the discrepancy is only a fluke to 1 in 100,000. This is a significant gain from an earlier estimate, less than a year ago, of a chance of 1 in 3,000.

These most precise Hubble measurements to date bolster the idea that new physics may be needed to explain the mismatch.

“The Hubble tension between the early and late universe may be the most exciting development in cosmology in decades,” said lead researcher and Nobel laureate Adam Riess of the Space Telescope Science Institute (STScI) and Johns Hopkins University, in Baltimore, Maryland. “This mismatch has been growing and has now reached a point that is really impossible to dismiss as a fluke. This disparity could not plausibly occur just by chance.”

Tightening the bolts on the ‘cosmic distance ladder’

Scientists use a “cosmic distance ladder” to determine how far away things are in the universe. This method depends on making accurate measurements of distances to nearby galaxies and then moving to galaxies farther and farther away, using their stars as milepost markers. Astronomers use these values, along with other measurements of the galaxies’ light that reddens as it passes through a stretching universe, to calculate how fast the cosmos expands with time, a value known as the Hubble constant. Riess and his SH0ES (Supernovae H0 for the Equation of State) team have been on a quest since 2005 to refine those distance measurements with Hubble and fine-tune the Hubble constant.

In this new study, astronomers used Hubble to observe 70 pulsating stars called Cepheid variables in the Large Magellanic Cloud. The observations helped the astronomers “rebuild” the distance ladder by improving the comparison between those Cepheids and their more distant cousins in the galactic hosts of supernovas. Riess’s team reduced the uncertainty in their Hubble constant value to 1.9% from an earlier estimate of 2.2%.

As the team’s measurements have become more precise, their calculation of the Hubble constant has remained at odds with the expected value derived from observations of the early universe’s expansion. Those measurements were made by Planck, which maps the cosmic microwave background, a relic afterglow from 380,000 years after the big bang.

The measurements have been thoroughly vetted, so astronomers cannot currently dismiss the gap between the two results as due to an error in any single measurement or method. Both values have been tested multiple ways.

“This is not just two experiments disagreeing,” Riess explained. “We are measuring something fundamentally different. One is a measurement of how fast the universe is expanding today, as we see it. The other is a prediction based on the physics of the early universe and on measurements of how fast it ought to be expanding. If these values don’t agree, there becomes a very strong likelihood that we’re missing something in the cosmological model that connects the two eras.”

Universe’s Expansion Rate Widens With New Hubble Data

This illustration shows the three basic steps astronomers use to calculate how fast the universe expands over time, a value called the Hubble constant. All the steps involve building a strong “cosmic distance ladder,” by starting with measuring accurate distances to nearby galaxies and then moving to galaxies farther and farther away. This “ladder” is a series of measurements of different kinds of astronomical objects with an intrinsic brightness that researchers can use to calculate distances. Among the most reliable for shorter distances are Cepheid variables, stars that pulsate at predictable rates that indicate their intrinsic brightness. Astronomers recently used the Hubble Space Telescope to observe 70 Cepheid variables in the nearby Large Magellanic Cloud to make the most precise distance measurement to that galaxy. Astronomers compare the measurements of nearby Cepheids to those in galaxies farther away that also include another cosmic yardstick, exploding stars called Type Ia supernovas. These supernovas are much brighter than Cepheid variables. Astronomers use them as “milepost markers” to gauge the distance from Earth to far-flung galaxies. Each of these markers build upon the previous step in the “ladder.” By extending the ladder using different kinds of reliable milepost markers, astronomers can reach very large distances in the universe. Astronomers compare these distance values to measurements of an entire galaxy’s light, which increasingly reddens with distance, due to the uniform expansion of space. Astronomers can then calculate how fast the cosmos is expanding: the Hubble constant. Credits: NASA, ESA and A. Feild (STScI)

How the new study was done

Astronomers have been using Cepheid variables as cosmic yardsticks to gauge nearby intergalactic distances for more than a century. But trying to harvest a bunch of these stars was so time-consuming as to be nearly unachievable. So, the team employed a clever new method, called DASH (Drift And Shift), using Hubble as a “point-and-shoot” camera to snap quick images of the extremely bright pulsating stars, which eliminates the time-consuming need for precise pointing.

“When Hubble uses precise pointing by locking onto guide stars, it can only observe one Cepheid per each 90-minute Hubble orbit around Earth. So, it would be very costly for the telescope to observe each Cepheid,” explained team member Stefano Casertano, also of STScI and Johns Hopkins. “Instead, we searched for groups of Cepheids close enough to each other that we could move between them without recalibrating the telescope pointing. These Cepheids are so bright, we only need to observe them for two seconds. This technique is allowing us to observe a dozen Cepheids for the duration of one orbit. So, we stay on gyroscope control and keep ‘DASHing’ around very fast.”

The Hubble astronomers then combined their result with another set of observations, made by the Araucaria Project, a collaboration between astronomers from institutions in Chile, the U.S., and Europe. This group made distance measurements to the Large Magellanic Cloud by observing the dimming of light as one star passes in front of its partner in eclipsing binary-star systems.

The combined measurements helped the SH0ES Team refine the Cepheids’ true brightness. With this more accurate result, the team could then “tighten the bolts” of the rest of the distance ladder that extends deeper into space.

The new estimate of the Hubble constant is 74 kilometers (46 miles) per second per megaparsec. This means that for every 3.3 million light-years farther away a galaxy is from us, it appears to be moving 74 kilometers (46 miles) per second faster, as a result of the expansion of the universe. The number indicates that the universe is expanding at a 9% faster rate than the prediction of 67 kilometers (41.6 miles) per second per megaparsec, which comes from Planck’s observations of the early universe, coupled with our present understanding of the universe.

So, what could explain this discrepancy?

One explanation for the mismatch involves an unexpected appearance of dark energy in the young universe, which is thought to now comprise 70% of the universe’s contents. Proposed by astronomers at Johns Hopkins, the theory is dubbed “early dark energy,” and suggests that the universe evolved like a three-act play.

Astronomers have already hypothesized that dark energy existed during the first seconds after the big bang and pushed matter throughout space, starting the initial expansion. Dark energy may also be the reason for the universe’s accelerated expansion today. The new theory suggests that there was a third dark-energy episode not long after the big bang, which expanded the universe faster than astronomers had predicted. The existence of this “early dark energy” could account for the tension between the two Hubble constant values, Riess said.

Another idea is that the universe contains a new subatomic particle that travels close to the speed of light. Such speedy particles are collectively called “dark radiation” and include previously known particles like neutrinos, which are created in nuclear reactions and radioactive decays.

Yet another attractive possibility is that dark matter (an invisible form of matter not made up of protons, neutrons, and electrons) interacts more strongly with normal matter or radiation than previously assumed.

But the true explanation is still a mystery.

Riess doesn’t have an answer to this vexing problem, but his team will continue to use Hubble to reduce the uncertainties in the Hubble constant. Their goal is to decrease the uncertainty to 1%, which should help astronomers identify the cause of the discrepancy.

The team’s results have been accepted for publication in The Astrophysical Journal.

The Hubble Space Telescope is a project of international cooperation between NASA and ESA (European Space Agency). NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore, Maryland, conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy in Washington, D.C.

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https://scitechdaily.com/important-threshold-crossed-in-mystery-of-the-universes-expansion-rate/

2019-04-27 13:52:38Z
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