#Baby model cosmos grows up to look like the real thing A supercomputer simulation has tracked the evolution of the universe from a mere 12 million years after the big bang until the present day.
It is the first to produce realistic-looking galaxies by the thousands and a triumph for our current understanding of the history of the universe.
If you take 40000 galaxies from the simulation and compare them to 40000 real galaxies you would have a very hard time distinguishing them says one of the simulation's creators Mark Vogelsberger of the Massachusetts institute of technology.
This tells you that our understanding of galaxy evolution is so complete now that we can make models that predict a universe that just looks like ours.
Previous simulations had focused on the properties of individual galaxies or on the weblike scaffold of dark matter that connects groups of galaxies.
Recent advances in supercomputing and a fresh computational approach let the recent simulation called Illustris do both at once.
Our main goal was to have a statistical sample of galaxies but also be able to say something about the characteristics of each galaxy says Vogelsberger.
He and his colleagues modelled a cube of space with sides that stretched to 347 million light years a fraction of the size of the observable universe today.
They divided it up into 12 billion smaller units and used equations that describe ordinary matter's behaviour in cosmic structures to calculate what should happen in each unit.
Instead of forcing the units to stay in a rigid grid the team allowed them to shift making the simulation more accurate as well as more computationally efficient than previous ones.
The simulation handles ordinary matter as well as enigmatic dark matter and dark energy. It also accounts for complex phenomena such as cooling gas star formation supernova explosions
and supermassive black holes pulling in material that gets too Close to run the simulation the team used several supercomputers in Europe and the US each
of which contained many central processing units or CPUS. By contrast an ordinary computer might have just one.
The entire simulation took 16 million CPU hours which means that running it on a single normal computer would take nearly 2000 years.
The resulting cosmos was almost indistinguishable from the real one we see today. As a demonstration the team compared a simulated version of the Hubble Ultra Deep Field observation to the real thing
which was made when the Hubble space telescope stared at one spot in the sky for nearly 12 days.
The code also managed to reproduce different types of galaxies including spiral galaxies like the Milky way and blob-shaped elliptical galaxies.
This is like simulating the whole US where previously it was like just simulating your neighbourhood says Michael Boylan-Kolchin at the University of Maryland in College Park who led one of the largest previous simulations called Millennium-II.
Some details weren't perfect however. For instance small galaxies in the simulation produced stars too early so they appeared older than we observe them to be today.
This is one of the failures of the model Vogelsberger says. What's more Boylan-Kolchin notes that some of the processes through which galaxies grow up such as star formation
and black hole radiation are still not very well understood making it difficult to tell whether the simulation gets them right.
However models like Illustris can also help elucidate these processes he says. The more we can get at these processes by trying to make realistic galaxies and seeing what works and
what doesn't that will give us information about how these processes work on smaller scales.
Journal reference: Nature DOI: 10.1038/nature1331 1
#Sun's fractal surprise could help fusion On earth THE sun has thrown us a fractal surprise.
An unexpected pattern has been glimpsed in the solar wind the turbulent plasma of charged particles that streams from the sun. It offers clues for handling plasmas that roil inside nuclear fusion reactors On earth.
Composed of charged particles such as protons and electrons the solar wind streams from the sun and pervades the solar system.
Its flow is turbulent containing eddies and moving at different speeds in different directions. It was thought that this turbulence was similar to that in a fluid behaving like mixing ocean currents
or the air flows that make aeroplane flights bumpy. Now Sandra Chapman of the University of Warwick UK and her colleagues have examined the solar wind's behaviour using NASA's twin STEREO spacecraft.
One flies just within Earth's orbit around the sun the other just outside it allowing the pair to obtain unique measurements of solar wind behaviour.
STEREO revealed that when the movement of the wind's particles is perpendicular to the sun's magnetic field they resemble a fluid with sections that are smooth interrupted by bursts of violence.
If you look out of a plane window you see mountain ranges and then long rolling plains.
This is what the perpendicular fluid turbulence is like says Chapman. But when the particles move in parallel with the field lines they behave very differently with the turbulence evenly spread like crinkly mountains that extend as far as the eye can see (see diagram.
Snowflakes shorelines and most recently black holes (see Turbulent black holes grow fractal skins as they feed) also exhibit such fractal behaviour.
These create energy in the same way as the sun by fusing a superheated plasma of hydrogen nuclei to form helium.
Enter the solar wind. Though less dense and cooler than the hydrogen of a fusion reactor the wind is a plasma
The great thing about solar wind turbulence is that the satellites sit right inside so it can be observed in exquisite detail says Steve Cowley of the Culham Centre for Fusion energy UK.
#Canada uses satellite to scold Russia over Ukraine Canada has blocked the launch of a satellite aboard a Russian rocket as a result of tensions over Russia's actions in Ukraine.
The move is a step up from a largely symbolic US ban on cooperating with Russia in space earlier this month.
The M3m satellite was built by Com Dev of Cambridge Ontario under contract for the Canadian space agency (CSA)
It was scheduled for launch on a Russian Soyuz rocket in June and was due to be shipped to the launch site in Baikonur Kazakhstan.
and the CSA meanwhile plan to launch the M3m satellite on another rocket. We are confident that the mitigations will be in place prior to the originally planned M3m in service date of September 2014 said Pley.
But unlike the US Canada doesn't have its own vehicles capable of launching a satellite into orbit
and so must hitch a ride on rockets launched by others. It isn't yet clear who might provide an alternative
Earlier this month NASA announced it was suspending cooperation with Russia although the International space station was excluded from the ban.
NASA only has a few smaller-scale joint activities with Russia such as an instrument aboard its Curiosity Mars rover
but there are no signs these have been affected by the boycott t
#Supernova found aligned with galactic magnifying glass A perfectly arranged exploding star and distant galaxy have created together a cosmic magnifying glass that could improve our understanding of the universe's expansion and dark matter.
Sometimes when a white dwarf star dies it explodes as a type 1a supernova. All supernovae in this class reach a very specific colour and peak brightness creating
what astronomers call a standard candle. As a result any deviations from this standard brightness and colour indicate
whether and by how much the light from the supernova is being messed with by other things like nearby galaxies or the expansion of the universe.
For example the gravity from a massive object like a galaxy can magnify light from another object like a supernova bending its light waves
and focusing them like a lens. We can only see this effect from Earth if the two objects are aligned perfectly.
Now a team led by Robert Quimby at the University of Tokyo Japan has confirmed the first case of this lensing effect in a type 1a supernova:
its light is being lensed by a galaxy in front of it. The supernova PS1-10afx was discovered in 2010 using the Pan starrs telescope in Hawaii.
Because it was so much brighter than normal it sparked controversy over whether it was a new type of supernova
or was being magnified by a gravitational lens. Quimby thought it must be lensing but nobody could see an intervening galaxy that could be doing the job.
There were good data taken before during and after the supernova and none of these showed obvious signs of a foreground object says Quimby.
Now his team has found a galaxy full of dim old stars that was hard to see against the bright background of the galaxy holding the supernova.
They calculate that it is the right size to make a normal type 1a supernova look about 30 times brighter about the same as the apparent brightness of PS1-10afx.
It's quite remarkable. I'm impressed they could find this thing says Brian Schmidt at the Australian National University in Canberra.
Schmidt used type 1a supernovae to deduce that the universe's expansion was accelerating a finding that won him the 2011 Nobel prize in physics along with Adam Riess and Saul Perlmutter.
The finding could help investigate dark matter the stuff thought to make up over 80 per cent of our universe's matter.
Since we know what the light from PS1-10afx should look like without gravitational lensing a standard candle any differences can be attributed to the mass of the galactic lens
and how that mass is distributed. And that in turn may depend on the galaxy's dark matter content
and distribution since massive dark matter halos are thought to cocoon galaxies making up most of a galaxy's mass.
We have these numerical simulations of dark matter that make pretty strong predictions of what dark matter halos should look like Schmidt says.
So if you could get a really good measurement of how dark matter is distributed within a bunch of galaxies one can essentially test the dark matter model better than we can at present.
Such systems could also help in the search to understand dark energy the mysterious entity thought to be behind the acceleration of the universe's expansion.
The ultimate fate of the universe is thought to depend on whether the acceleration is changing. Type 1a supernovae are used already to measure the rate of expansion over time
but having a gravitational lens offers a way to improve the measurements particularly if scientists can find more examples at different distances.
To assist with that Quimby's team offers advice on how to find lensed type 1a supernovae:
#Star dust casts doubt on recent big bang wave result An imprint left on ancient cosmic light that was attributed to ripples in spacetime
and hailed by some as the discovery of the century may have been caused by ashes from an exploding star.
when researchers report new results from the European space agency's Planck satellite. On 17 march researchers led by John Kovac of Harvard university announced that gravitational waves from the early universe had been found by a telescope called BICEP2 at the South pole.
The waves were said to be the smoking gun evidence for the theory of inflation which suggests that space expanded faster than the speed of light in the first moments after the universe's birth.
The announcement sent shock waves through the physics world. I was excited so recalls Philipp Mertsch of Stanford university in California.
or align the electromagnetic fields of photons they came into contact with in the infant universe.
ever since appear in every direction in the sky as the cosmic microwave background (CMB) radiation. But other things apart from gravitational waves such as dust can emit polarised photons.
To minimise the chances of this effect causing a false signal the BICEP 2 team pointed their telescope at a patch of sky far away from the Milky way's dusty disc.
A handful of nearby dust shells can be seen by radio telescopes appearing as giant loops looming above the Milky way's galactic disc.
and the giant loops detected by radio telescopes (blue lines). The effect of this finding on the BICEP2 result is not clear
because no thorough measurements have yet been made of how much polarised light the dust in our galaxy produces.
if you take the dust into account along with emissions from charged particles in the galaxy
For sure this BICEP2 result will put even more pressure on Planck's next release says Fabio Finelli a Planck team leader at Italy's National Institute for Astrophysics in Bologna.
#NASA'flying saucer'for Mars to land in Hawaii In June while beachgoers in Hawaii sit blissfully unaware a flying saucer will descend over the island of Kauai.
This is not a trailer for an alien invasion movie NASA is gearing up to conduct the first test flight of a disc-shaped spacecraft designed to safely land heavy loads
and one day people on the surface of Mars. The Low density supersonic decelerator (LDSD) will be lofted into the stratosphere from the US NAVY's Pacific Missile Range Facility on Kauai.
The inflatable technology is intended to help slow down vehicles after they enter the thin Martian atmosphere at supersonic speeds.
and crashing is stopping says Allen Chen at NASA's Jet propulsion laboratory in Pasadena California who oversaw the successful landing of the one-tonne Curiosity rover in 2012.
We really only have two options for stopping at Mars: rockets and aerodynamic drag. Until recently NASA had used parachutes and airbags for most robotic landings on Mars starting with the Viking mission in 1976.
But the heavier the load the harder it is to come in softly. For the car-sized Curiosity NASA invented an ambitious system called the sky crane
which combined parachutes with landing gear powered by retrorockets that could lower the rover to the surface on tethers.
However Curiosity pushed the weight limits of that technology and future human missions could require 40 to 100 metric tonnes per mission.
Such weight can't be slowed adequately by parachutes in the Martian air which is just 1 per cent as dense as Earth's. Unfortunately rocket-powered landings are out of the question too as the atmosphere is still just thick enough to buffet incoming spacecraft with more turbulence than thrusters can accommodate.
The LDSD design solves this quandary using a balloon-like decelerator and a giant parachute twice the size of Curiosity's. The decelerator would attach to the outer rim of a capsule-like entry vehicle.
To simulate Mars's thin atmosphere On earth the team in Hawaii will first lift a test vehicle fitted with the LDSD system to about 37 kilometres above the Pacific ocean using a high-altitude balloon.
and fire a small rocket to reach a height of 55 kilometres about halfway to the edge of space.
As it falls back to Earth the system will inflate and moments later the parachute will fire.
NASA has three more test flights in Hawaii planned for the LDSD and mission managers will review the results before deciding on next steps.
In addition to landing human missions on Mars the system could help robotic craft safely land in Martian mountains or highlands.
These areas have even less air available for slowing down a spacecraft via drag and so have been inaccessible with current technology.
Think about it like a bridge for humans to Mars. This is the next step in a sequence of technologies that would need to be developed d
#Squirting moons face off in race to find alien life Icebound seas just keep getting hotter at least as candidates for life beyond Earth.
Fresh discoveries have put two moons in our solar system neck and neck in the race.
In December astronomers announced hints of watery plumes spurting from Jupiter's large moon Europa potentially giving us a peek into a vast ocean likely to exist beneath its ice.
Saturn's moon Enceladus stole back the limelight last week when NASA reported firm evidence of an ocean linked to geysers at its south pole (see diagram below.
NASA's Cassini spacecraft flew through the geysers and detected water salts and carbon-based molecules.
Cassini scientist Luciano Iess at the Sapienza University of Rome Italy and colleagues have mapped now Enceladus's gravity
The constantly gushing geysers would let us easily sample those seas making Enceladus a prime target for a life-seeking mission says Cassini scientist Carolyn Porco.
and scoop up some of the plume for analysis avoiding a tricky landing on the moon's surface.
The habitable zone of Enceladus remains the most well studied well understood and accessible of all the destinations for finding life
Models suggest that the moon can host geothermal vents which would be hotspots for marine life
Data from NASA's Galileo probe which orbited Jupiter from 1995 to 2003 show clay-like minerals on Europa's surface probably debris from meteor impacts
And Jupiter's strong magnetic field means that intense radiation surrounds the moon which makes it difficult for spacecraft to operate.
For now Europa is slightly ahead in terms of funding. NASA's budget for next year includes $15 million to design possible missions there
and the agency is inviting proposals for instruments a probe could carry. Could Cassini yet yield insights that would swing things in favour of Enceladus?
The craft is in its twilight years and will end its mission in 2017. But first it will fly by Enceladus one more time
and the team will be watching for any molecular hydrogen in the plumes. Hydrogen is very short-lived
Europa is sized a good moon but Enceladus is tiny. That thing should be frozen solid and dead as a doorbell says NASA program scientist Curt Niebur who heads the committee that will evaluate science instruments for a Europa mission.
Instead it's incredibly lively. That's amazing. They're both unbelievably good candidates which is the shocking thing:
that we have not just one but two candidates for seeking life beyond Earth h
#NASA's Russia boycott may revitalise US space leadership So NASA has been dragged into the fallout over Russia's seizure of Crimea from Ukraine.
An internal memo made public this week revealed the space agency has suspended contact with Russia except for that concerning International space station (ISS) operations.
The memo stated that the suspension includes NASA travel to Russia and visits by Russian government representatives to NASA facilities bilateral meetings email and teleconferences or videoconferences.
This was confirmed in an official statement from NASA yesterday. Will this action influence Vladimir Putin
and his apparent dream of geographically reassembling parts of the Soviet union as a new Russian empire?
That's highly unlikely. So why do it? Space has a long history of serving as a surrogate for demonstrating US displeasure about foreign or domestic policy actions in other countries.
Though examples date back to the cold war the most recent case relates to China. China has been banned for years from participating in the ISS
In addition NASA has been banned legislatively from having bilateral relations with China since 2011. While ostensibly that ban relates to concerns about technology transfer the underlying reason has as much or more to do with Chinese restrictions on religious freedom.
or its relative isolation from meeting with NASA officials nor is it likely to. In fact China has pushed ahead with its own robotic lunar programme
and human spaceflight programme and works with many other countries including Russia in space. When the Soviet union collapsed
and the cold war ended the US pragmatically merged its human spaceflight programme specifically the ISS programme with the Soviet Mir space station programme inherited by the new Russian state.
The pragmatic intent was to keep lots of otherwise potentially unemployed Russian scientists and engineers from taking jobs in countries with dubious space programmes.
After all space technology is largely dual use of value to both military and civilian communities. The basics of rocket technology and missile technology are largely symbiotic.
It seemed a good idea at the time. Then after spending decades building the ISS the US cancelled the space shuttle the vehicle originally intended for transport to the ISS as part of its post-Apollo programme.
The first resident crew arrived at the ISS in 2000 aboard a Russian Soyuz spacecraft
but shuttle missions soon followed. After the shuttle's last flight in 2011 though the US became dependent on Russia for transport to the ISS using Soyuz at a cost of nearly $71 million for each seat it requires.
It would be hypocritical to say the least for the US to ban bilateral space relations with China over general displeasure with its form of government
NASA's suspension of working with the Russians will likely be received in Russia much the same way other sanctions over its actions in Ukraine have been:
or more specifically the keys to the rocket capable of getting crew to the ISS.
and rethinking the propensity of using space as a foreign policy surrogate. The bigger issue however is how to reassert US space leadership.
Without finally dealing with that the US may increasingly find itself being pushed around in space e
#Buried'Lake superior'seen on Saturn's moon Enceladus Saturn's icy moon Enceladus already known for spitting plumes of water into space just got even more interesting.
New gravity readings suggest it hosts a subsurface sea the size of Lake superior at its south pole
-and that this liquid water is in direct contact with the moon's core which is rich in nutrients.
Both findings boost hopes that the sea hosts life. The result comes hot on the heels of the discovery late last year that a second icy moon Europa
which orbits Jupiter also spews plumes of water. Both moons are now among the hottest prospects in the solar system for finding alien life
if only a suitable mission could be arranged NASA's Cassini orbiter first spotted spectacular plumes at Enceladus's south pole in 2005 shortly after arriving at Saturn.
The plumes shoot into space at supersonic speeds feeding one of Saturn's famous rings
and are known to contain both salts and organic compounds. They make an attractive target for exploration as a craft could potentially fly through them to take samples much simpler than landing on a moon.
Most astronomers thought that the plumes force their way out through cracks in an icy crust sitting over a sea of liquid water.
But until now no one knew how deep that sea went. Luciano Iess at the Sapienza University of Rome in Italy and his colleagues used radar On earth to track Cassini on three separate fly-bys of Enceladus
and watched how the spacecraft was accelerated by the moon's gravity. This allowed them to map the distribution of mass in the moon's interior.
They found that Enceladus has a rocky core and an icy crust. Before we knew almost nothing about the core beyond its likely existence.
Now we know roughly how big it is and also that it has a surprisingly low density says team member Francis Nimmo at the University of California Santa cruz. That might be due to open fractures
or low-density hydrated minerals like clays. Either answer suggests that the rock has been in substantial contact with water for instance allowing minerals to dissolve
and explaining the salty ice grains we see coming out of the surface. The team also found that the southern hemisphere has a stronger gravitational pull than its topography would suggest.
Hosting an ocean in contact with rocks boosts the chances that Enceladus hosts life because the rocks could leach elements like potassium sulphur and phosphorus vital for life into the water.
because it wouldn't be in contact with the rock says team member Jonathan Lunine at Cornell University in Ithaca New york. This gravity map hinting at a much larger ocean is a more favourable model for having some sort of life in Enceladus's interior.
and there are no firm plans for future craft to return to Saturn. However Cassini team member Carolyn Porco at the Space science Institute in Boulder Colorado has written a paper (soon to appear in the journal Astrobiology) arguing for a mission to collect samples from Enceladus and return them to Earth.
She says the new results bode well for such an effort. The next mission there can immediately get down to the business of searching for signs of life or its precursor chemistry.
The subsurface-sea idea is just the simplest possible interpretation of the gravity data cautions William Mckinnon at Washington University in St louis who was involved not in the work.
As for the possibility of the sea freezing completely it is true that Enceladus is losing a lot of heat to space
but astronomers suspect that this is an unusual episode. We are looking at Enceladus at a wonderful special time where it's very active
and there's a lot of heat Mckinnon says. Could the plumes deplete the sea completely? Probably not.
Even if they continue at the current rate the moon would only have lost 30 per cent of its water by mass
when the sun becomes a red giant in 6 billion years. A lot of things can happen in 6 billion years
Some future extraterrestrials visiting our solar system will be able to look at the naked rocky core of
what was once an ice moon. Journal reference: Science DOI: 10.1126/science. 125055 5
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