Astronomy, cosmology and space thread

[Nereus]

NASA gives the thumbs up to the Dream Chaser space plane

https://www.flightsafetyaustralia.com/2 ... ace-plane/

Sending supplies to the International Space Station (ISS) is something that has to happen on a regular basis so that the crew can carry out their work while orbiting Earth. As most missions last about six months, with three to six crew members aboard the ISS at any one time, several tonnes of food and supplies need to be sent to the ISS every few months.

Unlike us earthlings who can pop out to the local supermarket to stock up whenever we want to, the crew of ISS face unique challenges. In a recent book published by NASA, The International Space Station: Operating an Outpost in the New Frontier, chapter 14 ‘Vital Visiting Vehicles–Keeping the Remote Outpost Crewed and Operating’ states, ‘The logistics of keeping such the ISS running are complicated. In space, there are no grocery stores or home improvements stores. The “trash truck” only comes around every few months. Washers and dryers for clothing do not exist, and access to clean attire can take months. Much of the breathable air and drinkable water must be delivered. When supplies (e.g. bathroom tissue) are low, crew members cannot tap a few keys on the computer and wait for resupplies to arrive at the door. They call Mission Control and place their order, and then they wait.’

Now the wait may be quicker and easier. The Sierra Nevada Corporation (SNC) has convinced NASA that they can make cargo deliveries to the ISS with their high-tech space plane called the Dream Chaser and approval has been given to the company to begin full production of the spacecraft.

Dream Chaser program director at SNC, John Curry, says ‘NASA’s approval of full production of the first Dream Chaser spacecraft is a major indication we are on the right path towards increasing vital science return for the industry.’

As reported in Space News, a version of the Dream Chaser was originally in the running for a new spacecraft to take crew to the ISS but NASA ultimately awarded the contracts to SpaceX and Boeing. The SNC tweaked its designs and presented a new version of the Dream Chaser for cargo resupply missions.

The new design of the spacecraft has foldable wings that allows it to be placed inside the payload compartment of a rocket. Once in space, it will dock with the ISS, transfer cargo, then fly back to Earth, jettisoning its cargo module which will be incinerated in the atmosphere as the plane itself flies back down for a runway landing.

The spacecraft will make its debut in late 2020.

[Nereus]

Stratolaunch high-speed taxi test

https://www.flightsafetyaustralia.com/2 ... taxi-test/

Airborne launching of rockets into space has taken a giant leap forward with Stratolaunch having its first high-speed taxi test.

Stratolaunch, the aerospace venture created by Microsoft co-founder Paul Allen, says its twin-fuselage, six-engine aircraft raced as fast as 118 knots (219 kilometres per hour) down the runway at California’s Mojave Air and Space Port last week during its latest taxi test. That’s almost take-off speed for the Stratolaunch, which is the world’s largest plane.

The taxi test also included a brief ‘rotation authority manoeuvre’ where the plane’s nose gear lifted off the runway and is the latest of a series of taxi tests where the plane travels down the runway under its own power but does not get airborne.

As covered in Flight Safety Australia in June 2016, the purpose of the Stratolaunch is to provide a low-cost way of launching commercial satellites. It uses engines, fuel systems, hydraulics, avionics, landing gear and cockpits from two recycled Boeing 747s and has a wingspan of 117 metres (385 feet) which is 47 metres more than an Airbus A380.

It will carry rockets weighing more than 200 tonnes under its centre wing section and when it reaches an altitude around 35,000 feet (10,668 metres), the rockets will be launched.

This recent test suggests that after more than seven years of development and three months after Allen’s death, the plane is getting close to its first flight.

When Stratolaunch is ready to be airborne, it will take 18 to 24 months of test flights before it can receive certification from the Federal Aviation Administration (FAA). Once this stage is complete, the plane can begin its role as a launch platform—probably sometime next year or the year after.

Eventually, the plane could accommodate up to three rockets for separate launches during a single mission.

[Nereus]

Super Moon tonight:

https://www.timeanddate.com/astronomy/m ... -moon.html

Supermoon on Tuesday, February 19, 2019

When the Full Moon occurs during the Moon's closest approach to Earth, its perigee, it appears larger and brighter in the sky. This phenomenon is often called a supermoon.

[Nereus]

Super Moon tonight:

https://www.timeanddate.com/astronomy/m ... -moon.html

Supermoon on Tuesday, February 19, 2019

When the Full Moon occurs during the Moon's closest approach to Earth, its perigee, it appears larger and brighter in the sky. This phenomenon is often called a supermoon.

Don't know about Hua Hin, but it is clear tonight in Bangkok and the big moon is up.

[Big Boy]

It was the same here in Hua Hin.

[PeteC]

New Universe map unearths 300,000 more galaxies
Published: 19/02/2019 at 05:45 PM
Online news: https://www.bangkokpost.com/news/world/ ... s#cxrecs_s

PARIS - The known Universe just got a lot bigger.

A new map of the night sky published Tuesday charts hundreds of thousands of previously unknown galaxies discovered using a telescope that can detect light sources optical instruments cannot see.

The international team behind the unprecedented space survey said their discovery literally shed new light on some of the Universe's deepest secrets, including the physics of black holes and how clusters of galaxies evolve.

"This is a new window on the universe," Cyril Tasse, an astronomer at the Paris Observatory who was involved in the project, told AFP.

"When we saw the first images we were like: 'What is this?!' It didn't look anything at all like what we are used to seeing."

More than 200 astronomers from 18 countries were involved in the study, which used radio astronomy to look at a segment of sky over the northern hemisphere, and found 300,000 previously unseen light sources thought to be distant galaxies.

Radio astronomy allows scientists to detect radiation produced when massive celestial objects interact.

The team used the Low Frequency Array (LOFAR) telescope in the Netherlands to pick up traces -- or "jets" -- of ancient radiation produced when galaxies merge. These jets, previously undetected, can extend over millions of light years.

"With radio observations we can detect radiation from the tenuous medium that exists between galaxies," said Amanda Wilber, of the University of Hamburg.

"LOFAR allows us to detect many more of these sources and understand what is powering them."

The discovery of the new light sources may also help scientists better understand the behaviour of one of space's most enigmatic phenomena.

Black holes -- which have a gravitational pull so strong that no matter can escape them -- emit radiation when they engulf other high-mass objects such as stars and gas clouds.

Tasse said the new observation technique would allow astronomers to compare black holes over time to see how they form and develop.

"If you look at an active black hole, the jets (of radiation) disappear after millions of years, and you won't see them at a higher frequency (of light)," he said.

"But at a lower frequency they continue to emit these jets for hundreds of millions of years, so we can see far older electrons."

The Hubble telescope has produced images that lead scientists to believe there are more than 100 billion galaxies in the Universe, although many are too old and distant to be observed using traditional detection techniques.

The map created by the LOFAR observations, part of which was published in the journal Astronomy & Astrophysics, contains data equivalent to ten million DVDs yet charts just two percent of the sky.

The LOFAR telescope is made up of a Europe-wide network of radio antenna across seven countries, forming the equivalent of a 1,300-kilometre diameter satellite dish.

The team plans to create high-resolution images of the entire northern sky, which they say will reveal as many as 15 million as-yet undetected radio sources.

"The oldest objects in the Universe are around 11-12 billion light years old," said Tasse. "So we are going to see lots more of these objects."

[pharvey]

Quite incredible really.....

Japan’s Hayabusa 2 Successfully Touches Down on Ryugu Asteroid

"A Japanese spacecraft has successfully touched down on a speeding asteroid 300 million kilometres from the Earth as it attempts an audacious manoeuvre to collect samples and bring them back for scientists to study.

The Hayabusa 2 probe touched down on the asteroid Ryugu at around 11:30pm GMT on Thursday. Data from the probe showed changes in speed and direction, indicating it had reached the asteroid’s surface, according to officials from the Japan Aerospace Exploration Agency (JAXA).

A live webcast of the control room showed dozens of JAXA staff members nervously monitoring data ahead of the touchdown before exploding into applause after receiving a signal from Hayabusa2 that it had landed.

“We made a successful touchdown, including firing a bullet” into the Ryugu asteroid, Yuichi Tsuda, Hayabusa 2 project manager, told reporters.

“We made the ideal touchdown in the best conditions,” he said.

JAXA spokeswoman Chisato Ikuta said the control centre had “received data that shows that the probe is working normally and is healthy.”

Scientists are continuing to gather and analyse data from the probe, she said.

The probe was due to fire a bullet at the Ryugu asteroid, to stir up surface matter, which it will then collect for analysis back on Earth. The asteroid is thought to contain relatively large amounts of organic matter and water from some 4.6 billion years ago when the solar system was born.

The complicated procedure took less time than expected and appeared to go without a hitch, said Hayabusa 2 mission manager Makoto Yoshikawa.

“I’m really relieved now. It felt very long until the moment the touchdown happened,” he said.

He said the firing of the bullet - the first of three planned in this mission - “will lead to a leap, or new discoveries, in planetary science.”

The spacecraft is seeking to gather 10g of the dislodged debris with an instrument named the Sampler Horn that hangs from its underbelly.

Whatever material is collected by the spacecraft will be stored onboard until Hayabusa 2 reaches its landing site in Woomera, South Australia, in 2020 after a journey of more than three billion miles."

Full Article: - https://www.theguardian.com/science/201 ... u-asteroid

[Nereus]

Scientists set to reveal first true image of black hole

https://www.bangkokpost.com/news/world/ ... black-hole

PARIS: The world is finally about to see a black hole -- not an artist's impression or a computer-generated likeness, but the real thing.

At six press conferences across the globe scheduled for 1pm GMT (8pm Thailand) on Wednesday, scientists will unveil the first results from the Event Horizon Telescope (EHT), conceived precisely for that purpose.

It has been a long wait.
Of all the forces in the Universe that we cannot see -- including dark energy and dark matter -- none has frustrated human curiosity as thoroughly as the invisible, star-devouring monsters known as black holes.

Yet, the phenomena are so powerful that nothing nearby -- not even light -- can escape their gravitational pull.
"Over the years, we accumulated indirect observational evidence," said Paul McNamara, an astrophysicist at the European Space Agency and project scientist for the LISA mission that will track massive black hole mergers from space.
In September 2015, for example, the LIGO gravitational wave detectors in the United States measured two black holes smashing together.

"X-rays, radio-waves, light -– they all point to very compact objects, and the gravitational waves confirmed that they really are black holes, even if we have never actually seen one," McNamara told AFP.

Two candidates are vying to be in the first-ever image.
Oddsmakers favour Sagittarius A*, the black hole at the centre of our own spiral galaxy, the Milky Way.
Sag A* has four million times the mass of our Sun, and measures about 24 million kilometres across.

That may sound like a big target, but for the telescope array on Earth some 26,000 light years (245 trillion kilometres) away, it's like trying to photograph a golf ball on the Moon.

The other candidate is 1,500 times more massive still, ensconced in a faraway elliptical galaxy known as M87.
Comparing the two, distance and size balance out, making it roughly as easy (or hard) to pinpoint either.

- Ripples in time-space -
A black hole is a celestial object that compresses a huge mass into an extremely small space. The more mass, the larger the black hole.

At the same scale of compression, Earth's mass would fit inside a thimble, while the Sun's would be a mere six kilometres from edge to edge.

There are two types.
Garden-variety black holes -- up to 20 times more massive than the Sun -- form when the centre of a very big star collapses in on itself.

So-called supermassive black holes are at least a million times bigger than the Sun. Both Sag A* and M87 fall into this category.

The EHT is unlike any star-gazing instrument ever devised.
"Instead of constructing a giant telescope we combined several observatories as if they were fragments of a giant mirror," Michael Bremer, an astronomer at the Institute for Millimetric Radio Astronomy in Grenoble, told AFP.
Eight such radio telescopes scattered across the globe -- in Hawaii, Arizona, Spain, Mexico, Chile, and the South Pole -- zeroed in Sag A* and M87 on four different days in April 2017.

Each is at least a big as a football pitch. Together, they form a virtual telescope more than 12,000 kilometres across, the diameter of Earth.

Data collected by the far-flung array was to be collated by supercomputers at MIT in Boston and in Bonn, Germany.
"The imaging algorithms we developed fill the gaps of data we are missing in order to reconstruct a picture," the team said on their website.

Astrophysicists not involved in the project, including McNamara, are eagerly -- perhaps anxiously -- waiting to see if the findings challenge Einstein's theory of general relativity, which has never been tested on this scale.

The LIGO experiments from 2015 detected signature ripples in the curvatures of time-space during the black hole merger.
"Einstein's theory of general relativity says that this is exactly what should happen," McNamara said.
But those were tiny black holes compared with either of the ones under the gaze of the EHT.
"Maybe the ones that are millions of times more massive are different -- we just don't know yet," McNamara said.

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[pharvey]

India's Chandrayaan-2 Moon Mission Lifts off a Week After Aborted Launch

"India’s mission to the moon has blasted into space one week after a technical glitch forced scientists to abruptly halt its scheduled launch.
Thousands gathered to watch Chandrayaan-2 takeoff at 2.43pm local time (0913 GMT) on Monday from Satish Dhawan space centre in Sriharikota, north of Chennai. It will travel to the little-explored south pole of the moon.
Chandrayaan-2, which will travel to the little-explored south pole of the moon, launched at 2.43pm local time (0913 GMT) on Monday from Satish Dhawan space centre in Sriharikota, north of Chennai.
Chandrayaan-2 aims to become the first mission to conduct a surface landing on the lunar south pole region, where it will collect crucial information about the moon’s composition. It would be India’s first surface landing on the moon – a feat previously achieved by only Russia, the US and China.

The $141m (£113m) mission is a “demonstration of the growing sophistication of India’s space power,” said Dr Rajeswari Pillai Rajagopalan, head of the nuclear and space policy initiative at the Observer Research Foundation thinktank in Delhi."

AND THE UK STILL GIVES MILLIONS IN AID TO INDIA!!

[Nereus]

Scientists discover ‘Terminator’ tsunamis on the Sun's surface

https://www.engadget.com/2019/07/25/sol ... yptr=yahoo

Waves of hot plasma create sunspots and mark the end of a solar cycle.

Our Sun is quite literally a hotbed of activity. Scientists are learning more about our star's solar cycle, in which its magnetic field flips and its north and south poles swap approximately every 11 years. Little is known about what causes this dramatic shift, although it does seem to be related to sunspot activity. A new set of research papers has laid out more about why solar cycles end and how the cycles can trigger a tsunami of hot plasma to cascade through the Sun's interior.

One study identified "terminator events" which indicated that a solar cycle was coming to an end by observing the Sun's magnetic fields, spectral irradiance, radio flux and bright spots. Some of these signs have already been identified, and the scientists predict that the current solar cycle will end in the first half of 2020.

"The evidence for terminators has been hidden in the observational record for more than a century, but until now, we didn't know what we were looking for," said NCAR scientist Scott McIntosh, who worked on both studies. "By combining such a wide variety of observations over so many years, we were able to piece together these events and provide an entirely new look at how the Sun's interior drives the solar cycle."

Another study found that these terminator events could trigger "solar tsunamis" when the Sun's magnetic fields move to the surface and create sunspots. When they move through the Sun, they trap plasma behind them like a dam. And when two such fields meet, they destroy each other and release an epic wave of hot plasma.

The tsunami waves travel at an astonishing 300 meters per second and interact with other magnetic fields within the Sun's interior, lifting these fields and creating bright points on the surface which we know as sunspots.

The scientists will have the chance to see if their theories are correct when this solar cycle ends next year. "In the next year, we should have a unique opportunity to extensively observe a terminator event as it unfolds and then to watch the launch of Sunspot Cycle 25," McIntosh said. "We believe the results, especially if the terminator arrives when predicted, could revolutionize our understanding of the solar interior and the processes that create sunspots and shape the sunspot cycle."

NASA/SDO/AIA/HMI/Goddard Space Flight Center

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[PeteC]

Earth's roaming magnetic poles create longer periods of instability, study says

https://edition.cnn.com/2019/08/07/worl ... index.html

Unlike its geographical poles, Earth's magnetic poles that serve as the foundation of our navigation are actively moving.

The north magnetic pole has been slowly moving across the Canadian Arctic toward Russia since 1831, but its swift pace toward Siberia in recent years at a rate of around 34 miles per year has forced scientists to update the World Magnetic Model -- used by civilian navigation systems, the North Atlantic Treaty Organization, and US and British militaries -- a year ahead of schedule.

The magnetic field reverses its polarity every several hundred thousand years, where the magnetic north pole resides at the geographic South Pole. The last reversal took place 770,000 years ago.
In a new study, researchers discovered that the last field reversal took 22,000 years to complete -- much longer than anticipated or expected, the researchers said.

Although some believe reversals could happen over the course of a human life, the findings don't support that theory.

Researchers were able to study the reversal by analyzing a global survey of ocean sediments, Antarctic ice cores and lava flows. The details within those samples revealed how Earth's magnetic field has weakened, shifted partially, stabilized and reversed over a million years.

"Reversals are generated in the deepest parts of the Earth's interior, but the effects manifest themselves all the way through the Earth and especially at the Earth's surface and in the atmosphere," said Brad Singer, study author and University of Wisconsin-Madison geologist. "Unless you have a complete, accurate and high-resolution record of what a field reversal really is like at the surface of the Earth, it's difficult to even discuss what the mechanics of generating a reversal are."

Our planet's magnetic field is created by an interaction between the liquid iron outer core spinning around the solid inner core. When a reversal happens, the normally strong magnetic field weakens.
Rock formation acts as a way to track the changes in the magnetic field. Lava flows and sediments record the state of the magnetic field, marking when they were created. Geologists can use the samples like pieces of a puzzle, reconstructing the history of the magnetic field. The record goes back millions of years, but it's the most clear when looking at the last reversal.

"Lava flows are ideal recorders of the magnetic field. They have a lot of iron-bearing minerals, and when they cool, they lock in the direction of the field," Singer said. "But it's a spotty record. No volcanoes are erupting continuously. So we're relying on careful field work to identify the right records."

Radioisotope dating of lava flows and continuous magnetic readings from the ocean floor and Antarctic ice cores helped recreate a picture of the last reversal for the researchers.

Argon can be measured from the lava flows as the radioactive decay of potassium occurs in the rocks, while beryllium can be measured in the ice cores. A weakened magnetic field allows more cosmic radiation from space to strike our atmosphere, which creates more beryllium.

The actual reversal took less than 4,000 years -- a drop in the bucket when compared to Earth's timeline so far. But leading up to that reversal were 18,000 years of instability, including two temporary and partial reversals. This is twice as long as expected.

The magnetic field decreases in strength about 5% each century and signs of weakening in the field point to an upcoming reversal -- but it's hard to know when that reversal will happen.

If a reversal happened during our lifetime, it could impact navigation, satellites and communications. However, the researchers believe that we would have generations to adapt for long periods of instability in the magnetic field.

"I've been working on this problem for 25 years," Singer said. "And now we have a richer record and better-dated record of this last reversal than ever before."

[Jimbob]

We need Trump to tell the Poles 'go back to where you came from'.

[pharvey]

We need Trump to tell the Poles 'go back to where you came from'.

[PeteC]

Scientists detect biggest explosion since Big Bang

https://www.bbc.com/news/science-environment-51669384

Scientists have detected evidence of a colossal explosion in space - five times bigger than anything observed before.

The huge release of energy is thought to have emanated from a supermassive black hole some 390 million light years from Earth.

The eruption is said to have left a giant dent in the Ophiuchus galaxy cluster.

Researchers reported their findings in The Astrophysical Journal.

They had long thought there was something strange about Ophiuchus galaxy cluster, which is a giant aggregation containing thousands of individual galaxies intermingled with hot gas and dark matter. X-ray telescopes had spied a curious curved edge to it.

The speculation was that this might be the wall of a cavity that had been sculpted in its gas by emissions from a central black hole.

Black holes are famous for gorging on infalling matter, but they will also expel prodigious amounts of material and energy in the form of jets.

Scientists at first doubted their explanation however, because the cavity was so big; you could fit 15 of our own Milky Way galaxies in a row into the hole.

And that meant any black hole explosion would have to have been unimaginably prodigious.

But new telescope data from the Murchison Widefield Array (MWA) in Australia and the Giant Metrewave Radio Telescope (GMRT) in India seem to confirm it.

"In some ways, this blast is similar to how the eruption of Mount St Helens (volcano) in 1980 ripped off the top of the mountain," said Simona Giacintucci of the Naval Research Laboratory in Washington, DC, and lead author of the study.

[Nereus]

It's a leap year. So why do we need to add another day to our calendar?

https://www.abc.net.au/news/science/202 ... s/12010958

Happy birthday to everyone born on February 29. It's been four years, but today is the day all you leaplings can officially celebrate on your birthday.

For the rest of us it's an extra day of summer (or winter depending upon which hemisphere you're reading this in).
But did you know, you can't count on getting a bonus day every four years.

Why do we need a leap year?
Leap years help keep our calendars in synch with the seasons, said Jonti Horner, an astronomer at the University of Southern Queensland

"We have this idea that ... the year is exactly 365 days,"
"Unfortunately, the universe doesn't actually work like that.

In fact, there are two kinds of years, both of which take a little more than 365 days to complete.

The first, known as a sidereal year, is the time it takes for the Earth to go around the Sun and return to the same place in the sky. It takes 365.256 days to complete.#

But our calendar year is based on the time it takes to get from one vernal equinox to the next.
Known as the 'tropical year' it takes 365.24219 days.

It's a bit shorter than the sidereal year because the Earth wobbles on its axis.

"The seasons are due to which direction the Earth is pointing to in space, so in order to make the seasons align ...you've got a slightly different distance to cover," Dr Horner explained.

If we stuck with the notion a tropical year was only 365 days long, after 100 years our calendars would have shifted forward by 25 days.

Instead of the vernal equinox being on 21 March, it would be around 15 April.

"And that would confuse people because suddenly the seasons are out of whack with your calendar," Dr Horner said.
"So to remedy that we have an extra day almost every four years."

One of the earliest calendars to deal with the differences between time and the seasons was developed under the rule of Julius Caesar in 68 BC.

The Julian calendar added one day every four years to realign with the seasons.
At 365.25 days it was between a sidereal and tropical year.

"They got that wrong a couple of times at first, but they got it all ironed out by about 8 AD," Dr Horner said.
But the Julian calendar was out by a fortnight by the mid-1500s.

So in 1582 Pope Gregory XIII shifted the dates back by 10 days and came up with a new calendar that all countries use today.

Instead of having 100 leap years every 400 years the Gregorian calendar has 97.

This refines the number of days in a year down to 365.2425 days.
"Which is almost, but not exactly the same as 365.24219, but it's close enough that for hundreds, if not thousands, of years it will be bang on before starting to drift."

How is a leap year calculated?
Under the Gregorian calendar a leap year must be able to be divided by 4.

But if the year can be divided by 4 and by 100, it must also be divisible by 400 to count as a leap year.
So, for example, the year 2000 was a leap year, but 1900 was not. Although it can be divided by 4 and 100 (475 and 19) it can't be evenly divided by 400.

That means leap years will continue to happen like clockwork every four years up until 2096.

But 2100 will not be a leap year (apologies in advance to any babies born today but you're going to have to rethink your 80th birthday — or is it your 20th?).

Leap years will not happen on 2200 or 2300 either.

The eastern orthodox church uses another calendar known as the revised Julian calendar.
The maths of this calendar is even more complicated than the Gregorian calendar.

"The revised Julian calendar says when years are divisible by 100 they're not leap years unless years have remainders of 200 or 600 when you divide by 900.

But this calculation is even more precise — a year is 365.24222222 days — than the Gregorian calendar.
Luckily for everyone the two calendars match up until 28 February 2800.

Without leap years our calendar would be out of whack with our seasons. (Wikimedia Commons: Jay8085)

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