China to land space probe on the Moon’s far side

China will launch the Chang'e-4 lunar probe around 2018 to achieve mankind's first soft landing on the far side of the moon, said a white paper released by the State Council Information Office on Tuesday.
The Chang'e-4 lunar probe will "conduct in situ and roving detection and relay communications at earth-moon L2 point," said the document titled "China's Space Activities in 2016."

China will continue its lunar exploration project in the next five years, and strive to attain the automated extra-terrestrial sampling and returning technology by space explorers.

It plans to fulfil the three strategic steps of "orbiting, landing and returning" for the lunar exploration project by launching the Chang'e-5 lunar probe by the end of 2017 and realizing regional soft landing, sampling and return, according to the white paper.

Through the lunar exploration project, topographic and geological surveys will be implemented and laboratory research conducted on lunar samples, it said.

"Geological survey and research as well as low-frequency radio astronomy observation and research will be carried out targeting the landing area on the far side of the moon for a better understanding of the formation and evolution of the moon," it added.

Planets Forming In The Rings Around A Young Star?

As our ability to observe the universe, both near and far in space and time, has grown, astronomers have seen some wonderful things that have helped our understanding of the cosmos. And while we have seen things as brilliant as the birth of stars, we haven’t ever observed the formation of planets.

In fact, it is only in the last two decades that we have been able to find planets outside the solar system, even though we have known for much longer that exoplanets exist. It was difficult to find planets because they don’t have any light of their own, and therefore seeing the process of a planet’s formation, usually shielded by the overbearing light from its parent star, is almost impossible to observe.

LEFT: An ALMA image of the star HD 163296 and its protoplanetary disk as seen in dust. Photo: ALMA (ESO/NAOJ/NRAO)/Andrea Isella/B. Saxton (NRAO/AUI/NSF)

But astronomers from Rice University think they have observed the formation of two planets that orbit HD 163296, a young star (less than 10 million years old, compared to the sun which is about 5 billion years old) roughly twice as massive as the sun and located about 400 light-years away.

Being a star of the Herbig Ae variety, HD 163296 has a circumstellar disk that is made up of gases and dust. Led by Andrea Isella, the Rice astronomers mapped the gases in three dark rings around the star in its surrounding disk.

“Of the material that formed this disk, about 1 percent is dust particles and 99 percent is gas,” Isella said in a statement. “So if you only see the dust, you cannot tell if a ring was formed by a planet or another phenomenon. In order to distinguish and really tell if there are planets or not, you need to see what the gas is doing, and in this study, for the first time, we can see both the dust and the gas.”

The researchers think outer two rings, at distances of 100 and 160 astronomical units (AUs, which is about 150 million kilometres, the distance between the sun and Earth) were created as planets formed at those distances, gathering all the dust and gas in their paths as they formed. They are thought to be gas giants with masses similar to Saturn. The inner ring, at a distance of 60 AUs from the star, however, is not thought to contain a planet — owing to a much higher concentration of carbon monoxide isotopes than the other two rings — and is currently not explained by the researchers.

“The inner gap is mysterious. Whatever is creating the structure is removing the dust but there’s still a lot of gas,” Isella said.

Why must time be a dimension?

“It is old age, rather than death, that is to be contrasted with life. Old age is life’s parody, whereas death transforms life into a destiny: in a way it preserves it by giving it the absolute dimension. Death does away with time.” -Simone de Beauvoir

When we think about how we can move through the Universe, we immediately think of three different directions. Left-or-right, forwards-or-backwards, and upwards-or-downwards: the three independent directions of a Cartesian grid. All three of those count as dimensions, and specifically, as spatial dimensions. But we commonly talk about a fourth dimension of a very different type: time. But what makes time a dimension at all? That’s this week’s Ask Ethan question from Thomas Anderson, who wants to know:

I have always been a little perplexed about the continuum of 3+1 dimensional Space-time. Why is it always 3 [spatial] dimensions plus Time?

Let’s start by looking at the three dimensions of space you’re familiar with.

On the surface of a world like the Earth, two coordinates, like latitude and longitude, are sufficient to define a location. Image credit: Wikimedia Commons user Hellerick.

Here on the surface of the Earth, we normally only need two coordinates to pinpoint our location: latitude and longitude, or where you are along the north-south and east-west axes of Earth. If you’re willing to go underground or above the Earth’s surface, you need a third coordinate — altitude/depth, or where you are along the up-down axis — to describe your location. After all, someone at your exact two-dimensional, latitude-and-longitude location but in a tunnel beneath your feet or in a helicopter overhead isn’t truly at the same location as you. It takes three independent pieces of information to describe your location in space.

Your location in this Universe isn’t just described by spatial coordinates (where), but also by a time coordinate (when). Image credit: Pixabay user rmathews100.

But spacetime is even more complicated than space, and it’s easy to see why. The chair you’re sitting in right now can have its location described by those three coordinates: x, y and z. But it’s also occupied by you right now, as opposed to an hour ago, yesterday or ten years from now. In order to describe an event, knowing where it occurs isn’t enough; you also need to know when, which means you need to know the time coordinate, t. This played a big deal for the first time in relativity, when we were thinking about the issue of simultaneity. Start by thinking of two separate locations connected by a path, with two people walking from each location to the other one.

Two points connected by a 1-dimensional (linear) path. Image credit: Wikimedia Commons user Simeon87.

You can visualize their paths by putting two fingers, one from each hand, at the two starting locations and “walking” them towards their destinations. At some point, they’re going to need to pass by one another, meaning your two fingers are going to have to be in the same spot at the same time. In relativity, this is what’s known as a simultaneous event, and it can only occur when all the space components and all the time components of two different physical objects align.

This is supremely non-controversial, and explains why time needs to be considered as a dimension that we “move” through, the same as any of the spatial dimensions. But it was Einstein’s special theory of relativity that led his former professor, Hermann Minkowski, to devise a formulation that put the three space dimensions and the one time dimension together.

Whether flat or curved, moving through space has implications for moving through time as well. Image credit: Pixabay user Johnson Martin.

We all realize that to move through space requires motion through time; if you’re here, now, you cannot be somewhere else now as well, you can only get there later. In 1905, Einstein’s special relativity taught us that the speed of light is a universal speed limit, and that as you approach it you experience the strange phenomena of time dilation and length contraction. But perhaps the biggest breakthrough came in 1907, when Minkowski realized that Einstein’s relativity had an extraordinary implication: mathematically, time behaves exactly the same as space does, except with a factor of c, the speed of light in vacuum, and a factor of I, the imaginary number √(-1).

An example of a light cone, the three-dimensional surface of all possible light rays arriving at and departing from a point in spacetime. Image credit: Wikimedia Commons user MissMJ.

Putting all of these revelations together yielded a new picture of the Universe, particularly as respects how we move through it.

• If you’re completely stationary, remaining in the same spatial location, you move through time at its maximal rate.
• The faster you move through space, the slower you move through time, and the shorter the spatial distances in your direction-of-motion appear to be.
• And if you were completely massless, you would move at the speed of light, where you would traverse your direction-of-motion instantaneously, and no time would pass for you.

A stationary observer sees time pass normally, but an observer moving rapidly through space will have their clock run slower relative to the stationary observer. Image credit: Michael Schmid of Wikimedia Commons.

From a physics point of view, the implications are astounding. It means that all massless particles are intrinsically stable, since no time can ever pass for them. It means that an unstable particle, like a muon created in the upper atmosphere, can reach the Earth’s surface, despite the fact that multiplying its lifetime (2.2 µs) by the speed of light yields a distance (660 meters) that’s far less than the distance it must travel. And it means that if you had a pair of identical twins and you left one on Earth while the other took a relativistic journey into space, the journeying twin would be much younger upon return, having experienced the passage of less time.

Mark and Scott Kelly at the Johnson Space Center, Houston Texas; one spent a year in space (and aged slightly less) while the other remained on the ground. Image credit: NASA.

As Minkowski said in 1908,

The views of space and time which I wish to lay before you have sprung from the soil of experimental physics, and therein lies their strength. They are radical. Henceforth, space by itself, and time by itself, are doomed to fade away into mere shadows, and only a kind of union of the two will preserve an independent reality.

Today, the formulation of spacetime is even more generic, and encompasses the curvature inherent to space itself, which is how special relativity got generalized. But the reason time is just as good a dimension as space is because we’re always moving through it, and the reason it’s sometimes written as a “1″ in “3+1″ (instead of just treated as another “1″ of the “4″) is because increasing your motion through space decreases your motion through time, and vice versa. (Mathematically, this is where the I comes in.)

Having your camera anticipate the motion of objects through time is just one practical application of the idea of time-as-a-dimension. The remarkable thing is that anyone, regardless of their motion through space relative to anyone else, will see these same rules, these same effects and these same consequences. If time weren’t a dimension in this exact way, the laws of relativity would be invalid, and there might yet be a valid concept such as absolute space. We need the dimensionality of time for physics to work the way it does, and yet our Universe provides for it oh so well. Be proud to give it a “+1” in all you do.

Alien life could thrive in the clouds of failed stars

There’s an abundant new swath of cosmic real estate that life could call home – and the views would be spectacular. Floating out by themselves in the Milky Way galaxy are perhaps a billion cold brown dwarfs, objects many times as massive as Jupiter but not big enough to ignite as a star. According to a new study, layers of their upper atmospheres sit at temperatures and pressures resembling those on Earth, and could host microbes that surf on thermal updrafts.

The idea expands the concept of a habitable zone to include a vast population of worlds that had previously gone unconsidered. “You don’t necessarily need to have a terrestrial planet with a surface,” says Jack Yates, a planetary scientist at the University of Edinburgh in the United Kingdom, who led the study.

Atmospheric life isn’t just for the birds. For decades, biologists have known about microbes that drift in the winds high above Earth’s surface. And in 1976, Carl Sagan envisioned the kind of ecosystem that could evolve in the upper layers of Jupiter, fueled by sunlight. You could have sky plankton: small organisms he called “sinkers.” Other organisms could be balloon-like “floaters,” which would rise and fall in the atmosphere by manipulating their body pressure. In the years since, astronomers have also considered the prospects of microbes in the carbon dioxide atmosphere above Venus’s inhospitable surface.

Yates and his colleagues applied the same thinking to a kind of world Sagan didn’t know about. Discovered in 2011, some cold brown dwarfs have surfaces roughly at room temperature or below; lower layers would be downright comfortable. In March 2013, astronomers discovered WISE 0855-0714, a brown dwarf only seven light years away that seems to have water clouds in its atmosphere. Yates and his colleagues set out to update Sagan’s calculations and to identify the sizes, densities, and life strategies of microbes that could manage to stay aloft in the habitable region of an enormous atmosphere of predominantly hydrogen gas. Sink too low and you are cooked or crushed. Rise too high and you might freeze.

On such a world, small sinkers like the microbes in Earth’s atmosphere or even smaller would have a better chance than Sagan’s floaters, the researchers will report in an upcoming issue of the Astrophysical Journal. But a lot depends on the weather: if upwelling winds are powerful on free-floating brown dwarfs, as seems to be true in the bands of gas giants like Jupiter and Saturn, heavier creatures can carve out a niche. In the absence of sunlight, they could feed on chemical nutrients. Observations of cold brown dwarf atmospheres reveal most of the ingredients Earth life depends on: carbon, hydrogen, nitrogen, and oxygen, though perhaps not phosphorous.

The idea is speculative but worth considering, says Duncan Forgan, an astrobiologist at the University of St. Andrews in the United Kingdom, who did not participate in the study but says he is close to the team. “It really opens up the field in terms of the number of objects that we might then think, well, these are habitable regions.”

So far, only a few dozen cold brown dwarfs have been discovered, though statistics suggest there should be about ten within thirty light-years of Earth. These should be ripe targets for the James Webb Space Telescope (JWST), which is sensitive in the infrared where brown dwarfs shine brightest. After it launches in 2018, JWST should reveal the weather and the composition of their atmospheres, says Jackie Faherty, an astronomer at the Carnegie Institution for Science in Washington, D.C. “We’re going to start getting gorgeous spectra of these objects,” she says. “This is making me think about it.”

Testing for life would require anticipating a strong spectral signature of microbe byproducts like methane or oxygen, and then differentiating it from other processes, Faherty says. Another issue would be explaining how life could arise in an environment that lacks the water-rock interfaces, like hydrothermal vents, where life is thought to have begun on Earth. Perhaps life could develop through chemical reactions on the surfaces of dust grains in the brown dwarf’s atmosphere, or perhaps it gained a foothold after arriving as a hitchhiker on an asteroid. “Having little microbes that float in and out of a brown dwarf atmosphere is great,” Forgan says. “But you’ve got to get them there first.”

Indian astrophysicist wins 10-year-old bet on dark energy

David Wiltshire has gifted a decorative lamp worth $200 to Thanu Padmanabham.

An Indian astrophysicist, named Thanu Padmanabham, who extended Albert Einstein’s theory on Dark Energy has won a 10-year-old bet with a New Zealand-based astrophysicist who had challenged him for the theory.

On December 1, the New Zealand astrophysicist, David Wiltshire, from the University of Canterbury, announced that he had conceded the wager to India’s astrophysicist Thanu Padmanabham on the nature of dark energy.

During a planetary talk on December 15, 2006 at the t an international physics symposium in Australia in 2006, Padmanabham challenged the audience stating that in the next ten years there will be no evidence to contradict the hypothesis that dark energy (cosmological constant) is the root cause of accelerated expansion of the universe. That is, dark energy is a mathematical term called the "cosmological constant" that Einstein had initially proposed in his equations, but abandoned.

It was Witlshire who accepted the challenge to disproof Padmanabham’s dark energy theory.

Dark energy was discovered in late 1990s by observing distant exploding stars that are said to push everything in the universe away from everything else. Studies suggest that Dark matter makes up about 72 per cent of the all the matter-energy in the universe, while the visible- matter in the universe including stars, planet and galaxies make up only 4 per cent.

Over the past decade, Padmanabham continued with his calculations, and four years ago Padmanabham with his daughter co-authored a paper in which they derived the numerical value of the cosmological constant.

Under the written terms of the wager, Wiltshire has gifted a decorative lamp worth $200, whose colour output can be altered using a mobile app, to Padmanabham.

Tags: astrophysicist, dark energy, albert einstein

This 6-foot wide asteroid is the smallest ever found Read

Astronomers have obtained observations of the smallest asteroid ever characterized in detail. At 2 meters (6 feet) in diameter, the tiny space rock is small enough to be straddled by a person in a hypothetical space-themed sequel to the iconic bomb-riding scene in the movie "Dr. Strangelove."

Interestingly, the asteroid, named 2015 TC25, is also one of the brightest near-Earth asteroids ever discovered. Using data from four different telescopes, a team of astronomers led by Vishnu Reddy, an assistant professor at the University of Arizona's Lunar and Planetary Laboratory, reports that 2015 TC25 reflects about 60 percent of the sunlight that falls on it.

Discovered by the UA's Catalina Sky Survey last October, 2015 TC25 was studied extensively by Earth-based telescopes during a close flyby that saw the micro world sailing past Earth at 128,000 kilometers, a mere third of the distance to the moon.

In a paper published in The Astronomical Journal, Reddy argues that new observations from the NASA Infrared Telescope Facility and Arecibo Planetary Radar show that the surface of 2015 TC25 is similar to a rare type of highly reflective meteorite called an aubrite. Aubrites consist of very bright minerals, mostly silicates, that formed in an oxygen-free, basaltic environment at very high temperatures. Only one out of every 1,000 meteorites that fall on Earth belong to this class.

"This is the first time we have optical, infrared and radar data on such a small asteroid, which is essentially a meteoroid," Reddy said. "You can think of it as a meteorite floating in space that hasn't hit the atmosphere and made it to the ground — yet."

Small near-Earth asteroids such as 2015 TC25 are in the same size range as meteorites that fall on Earth. Astronomers discover them frequently, but not very much is known about them as they are difficult to characterize. By studying such objects in more detail, astronomers hope to better understand the parent bodies from which these meteorites originate.

Asteroids are remaining fragments from the formation of the solar system that mostly orbit the sun between the orbits of Mars and Jupiter today. Near-Earth asteroids are a subset that cross Earth's path. So far, more than 15,000 near-Earth asteroids have been discovered.

Scientists are interested in meteoroids because they are the precursors to meteorites impacting Earth, Reddy said.

"If we can discover and characterize asteroids and meteoroids this small, then we can understand the population of objects from which they originate: large asteroids, which have a much smaller likelihood of impacting Earth," he said. "In the case of 2015 TC25, the likelihood of impacting Earth is fairly small."

The discovery also is the first evidence for an asteroid lacking the typical dust blanket — called regolith — of most larger asteroids. Instead, 2015 TC25 consists essentially of bare rock. The team also discovered that it is one of the fastest-spinning near-Earth asteroids ever observed, completing a rotation every two minutes.

Probably, 2015 TC25 is what planetary scientists call monolithic, meaning it is more similar to a "solid rock" type of object than a "rubble pile" type of object like many large asteroids, which often consist of many types of rocks held together by gravity and friction. Bennu, the object of the UA-led OSIRIS-REx sample return mission, is believed to be the latter type.

As far as the little asteroid's origin is concerned, Reddy believes it probably was chipped off by another impacting rock from its parent, 44 Nysa, a main-belt asteroid large enough to cover most of Los Angeles.

"Being able to observe small asteroids like this one is like looking at samples in space before they hit the atmosphere and make it to the ground," Reddy say. "It also gives us a first look at their surfaces in pristine condition before they fall through the atmosphere."

The telescope consortium used in this project includes University of Hawaii/NASA IRTF, USRA/Arecibo Planetary Radar, New Mexico Institute of Mining and Technology/Magdalena Ridge Observatory, Northern Arizona University and Lowell Observatory/Discovery Channel Telescope. Reddy's research on 2015 TC25 is funded by NASA's Near-Earth Object Observations program.

'Shockingly' cold gas cloud surrounding early giant galaxy surprises scientists

The discovery of an enormous reservoir of ultra-cold gas surrounding a distant galaxy has reshaped our scientific understanding of how stars and galaxies formed in the early universe.

An international team of scientists detected the huge halo of gas, 100 billion times the mass of our Sun, surrounding the Spider web galaxy, a massive galaxy surrounded by smaller galaxies about 10 billion light-years from Earth.

Until now, it was thought early galaxies were formed by the merging of smaller galaxies, but the growth of the Spiderweb galaxy appears to be fuelled by the cold cloud, scientists reported today in the journal Science.

"This completely changes the way we think that clusters of galaxies form," said Professor Ray Norris, an astrophysicist at CSIRO and Western Sydney University and co-author of the study.

"We're realising that lots of things we thought we knew about the universe are really based on what's going on in the modern universe.

"As we learn more and more about the early universe, we're realising there's quite a few things that are pretty different back there."

The research team expected the cluster of galaxies they were looking at, which formed about 3 billion years after the Big Bang, to be hot and violent as galaxies collided and merged.

But instead, they found that the central, larger galaxy was surrounded by an "enormous halo" of very cold gas with stars forming inside it.

"Nobody expected to see that," Professor Norris said.

The gas cloud, which had a temperature of about -200 degrees Celsius and was made up largely of carbon monoxide was a "major component" of star creation, he said, though the cannibalisation of small galaxies also played a part.

The discovery was made using Australia's Compact Array, a five-dish radio telescope in New South Wales, and the Very Long Array in New Mexico, to detect the carbon monoxide in the cold gas cloud.

While several telescopes around the world can detect carbon monoxide, Professor Norris said the wavelength range of the Compact Array made it the only one able to detect it at such a large distance from Earth.

The combined use of the VLA (which imaged individual galaxies in the cluster) and the Compact Array (which detected the gas) formed a picture of what was going on in the distant cluster.

"It's actually a combination of using these two telescopes together that really finally showed us what's going on," Professor Norris said.

More questions than answers

The discovery raises further questions about the nature of the early universe and the formation of stars.

Professor Norris said it was not yet clear exactly how the cold gas cloud came to be around the Spiderweb galaxy, but that it couldn't have come from the Big Bang because of its high carbon monoxide content.

"This gas has to have come from galaxies, even if it's early in the lifetime of the universe. So we really don't know [where it came from]. This is another really good question," he said.

The next step will be to image other clusters of galaxies from a similar time period to see whether they're also surrounded by vast gaseous reservoirs.

The Spiderweb galaxy, seen here in the centre of the galaxy cluster, as captured by the Hubble Space Telescope. Supplied: NASA/ESA/G. Miley/R. Overzier/ACS Science Team

"The impetus will be to look for other examples of this. I'm sure we, and other groups, will start looking at other clusters and my guess is we'll probably see similar things in other clusters now," Professor Norris said.

He said the discovery deepens our scientific understanding of those first billions of years after the Big Bang, when the universe was still forming.

"There's a number of ideas that, if you asked astronomers 10 years ago, they'd tell you it's this or that, and we've had to abandon some of those ideas in the early universe," he said.

"So this new discovery, it fits into the context of things we're seeing.

Tangled threads weave through cosmic oddity

New observations from the NASA/ESA Hubble Space Telescope have revealed the intricate structure of the galaxy NGC 4696 in greater detail than ever before. The elliptical galaxy is a beautiful cosmic oddity with a bright core wrapped in system of dark, swirling, thread-like filaments.

NGC 4696 is a member of the Centaurus galaxy cluster, a swarm of hundreds of galaxies all sitting together, bound together by gravity, about 150 million light-years from Earth and located in the constellation of Centaurus.

Right ascension 12h 48m 49.3s | Declination −41° 18′ 40″ | Mag +11.4

Despite the cluster’s size, NGC 4696 still manages to stand out from its companions — it is the cluster’s brightest member, known for obvious reasons as the Brightest Cluster Galaxy . This puts it in the same category as some of the biggest and brightest galaxies known in the Universe.

Even if NGC 4696 keeps impressive company, it has a further distinction: the galaxy’s unique structure. Previous observations have revealed curling filaments that stretch out from its main body and carve out a cosmic question mark in the sky (heic1013), the dark tendrils encircling a brightly glowing centre.

An international team of scientists, led by astronomers from the University of Cambridge, UK, have now used new observations from the NASA/ESA Hubble Space Telescope to explore this thread-like structure in more detail. They found that each of the dusty filaments has a width of about 200 light-years, and a density some 10 times greater than the surrounding gas. These filaments knit together and spiral inwards towards the centre of NGC 4696, connecting the galaxy’s constituent gas to its core.

In fact, it seems that the galaxy’s core is actually responsible for the shape and positioning of the filaments themselves. At the centre of NGC 4696 lurks an active supermassive black hole. This floods the galaxy’s inner regions with energy, heating the gas there and sending streams of heated material outwards.

It appears that these hot streams of gas bubble outwards, dragging the filamentary material with them as they go. The galaxy’s magnetic field is also swept out with this bubbling motion, constraining and sculpting the material within the filaments.

At the very centre of the galaxy, the filaments loop and curl inwards in an intriguing spiral shape, swirling around the supermassive black hole at such a distance that they are dragged into and eventually consumed by the black hole itself.

Understanding more about filamentary galaxies such as NGC 4696 may help us to better understand why so many massive galaxies near to us in the Universe appear to be dead; rather than forming new-born stars from their vast reserves of gas and dust, they instead sit quietly, and are mostly populated with old and aging stars. This is the case with NGC 4696. It may be that the magnetic structure flowing throughout the galaxy stops the gas from creating new stars.