At the height of our adoration of atomic energy, space agencies experimented with launching nuclear-powered spacecraft into orbit around the earth.

It makes sense if you think about it.

Radioactive materials, like uranium-235, can power a tiny satellite for years. They're more reliable than batteries and provide more energy than solar panels.

But back then, space-faring nations weren't as concerned with radioactive waste. Nuclear disasters like Three Mile Island and Chernobyl hadn't happened yet, and now we're much more worried about radiation exposure.

That's why the last nuclear-powered satellite, launched by the Soviet Union, blasted into orbit in 1988.

More than 30 different nuclear-reactor-powered satellites still orbit the earth. The US launched only one while the USSR launched all the rest.

Those nuclear reactors are similar to the ones in nuclear power plants on the ground. Uranium-235 undergoes fission, where its nucleus splits, giving off energy. This energy can be converted into electricity to power satellite instruments, or your house.

America's uranium-fueled SNAP-10A entered into an orbit of 575 miles above the earth in 1965. It operated for 43 days before it stopped responding. It's now in a slow trajectory to hit the ground in about 3,000 years. By then, hopefully, its radioactive cargo will be mostly harmless.

But if any of these nuclear-reactor-powered satellites collide with another object in space, or suddenly crash to the ground, they could release radioactivity.

The Soviet Union had a few such mishaps since it launched all those nuclear satellites. In 1978, its spy satellite, Kosmos 954, crashed into the Northwest Territories, scattering radioactivity across almost 48,000 square miles. The USSR had to pay Canada $10 million for the damage.

And in 1995, NASA scientists found a cloud of liquid, radioactive sodium and potassium coolant in orbit. The space agency eventually figured out that it came from the Soviet satellite Kosmos 1900. Something else in space crashed into it, causing the nuclear reactor to leak. The cloud of radioactive fluids is still floating up there, and space agencies continue to monitor it.

The good news is that all of these dead nuclear-reactor-powered satellites are in orbits higher than 430 miles. There's barely any air molecules at that height to slow down the satellites, so it should take them hundreds or thousands of years to wind their way back to the earth — at which point much of their radioactive contents will have significantly decayed.

But NASA and Roscosmos, Russia's space agency, are reportedly looking into building nuclear engines again. This time, they want to build hyperefficient rockets that might one day take humans to Mars.

If this sounds like science-fiction, it's not. NASA built several perfectly functional nuclear rocket engines from 1955 through 1973.

Here's one called NERVA being test-fired in the desert:

Those programs ended abruptly, however, because of environmental and budget concerns.

It remains to be seen if NASA or Roscosmos can keep funding, public support, and safety moving in its favor.

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NASA's Jet Propulsion Laboratory just released some amazing new footage of their recent fly-bys of Mars.

Produced by Emmanuel Ocbazghi

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NASA's Deep Space Climate Observatory (DSCOVR) captured these amazing images of the moon's shadow crossing the western Pacific during Wednesday's total solar eclipse.

The GIF above was compiled from 13 images taken by the Earth Polychromatic Imaging Camera (EPIC) and Cassegrain telescope aboard the satellite.

DSCOVR is parked in space a million miles away, positioned between the Earth and the Sun to get a constant, sunlit view of our planet.

The satellite normally takes a shot every 108 minutes, but for the March 8-9 eclipse, the EPIC team snapped one every 20 minutes, capturing the entire four-hour-and-20-minute eclipse in 13 images.

NASA also uses the DSCOVR satellite to monitor how much solar energy is emitted off of the Earth into space. In the coming weeks, scientists will analyze this data, collected by the National Institute of Standards and Technology Advanced Radiometer (NISTAR) aboard the satellite.

Until then, we'll be watching this over and over and over again.

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NOW WATCH: Watch stunning footage of last night’s solar eclipse

Imagine a spacecraft propelled by nothing but light.

A massive aluminum-coated sail stretches wide, capturing the momentum from photons when they reflect off the surface. The photons' energy is transferred to the sail, slowly but surely propelling it forward. The continuous momentum allows it to soar through space, no rocket required.

Novelists, poets, and scientists have envisioned spacecraft powered by solar sails since the 1600s.

But now this fanciful concept is actually entering into reality.

NASA, the European Space Agency (ESA), the Japanese Aerospace Exploration Agency (JAXA), and The Planetary Society have all either deployed solar sail-powered spacecraft or are looking into it.

Here's how they could revolutionize space exploration.

Solar sails use light to move just like sailboats use wind.

Eliminating the need for rocket thrusters to position the satellite or spacecraft, solar sails can be much smaller and lighter. The Planetary Society's LightSail is about the size of a loaf of bread.

But its sail, which deploys once it's in space, stretches 344 square feet.

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Source: The Planetary Society

"You are here to help humanity become a spacefaring species."

So said the opening line of a brochure for a workshop that took place in August 2014.

It was a meeting of some of the greatest scientists and professionals in the space business and beyond, including gene editing maverick George Church and Peter Diamandis from the XPrize Foundation.

The workshop's goal: to explore and develop low-cost options for building a human settlement on the moon.

"You are here to make this moonshot a reality," said the brochure.

NASA astrobiologist Chris McKay helped organize the meeting, and then he edited a special issue in the journal New Space to publish the papers that came out of the workshop. Those papers just came online this morning, and Popular Science had exclusive pre-publication access.

Together, the 9 papers help to build momentum for an idea that's growing throughout the planetary science and commercial space communities. The details differ between papers, they all say roughly the same thing: that we can set up a permanent, inhabited base on the moon, soon, and without breaking the bank.

Of course, this isn't the first time scientists have talked about returning to the moon.

"The reason all the previous plans for going back to the moon have failed is that they're just way too expensive," says McKay. "The space program is living in a delusion of unlimited budgets, which traces back to Apollo."

The Apollo program that put the first men on the moon would have cost $150 billion by today's standards. For reference, NASA's entire budget for the year of 2016 is $19.3 billion.

The New Space papers, by contrast, conclude that we could set up a small lunar base for $10 billion or less, and we could do it by 2022.

"The big takeaway," says McKay, "is that new technologies, some of which have nothing to do with space--like self-driving cars and waste-recycling toilets--are going to be incredibly useful in space, and are driving down the cost of a moon base to the point where it might be easy to do."

Why go back to the moon?

Currently, NASA has no plans to send humans back to the moon--instead it's focusing on getting to Mars in the 2030s. But McKay and others think we can't possibly go hiking on Mars if we don't first learn to camp in our own backyard.

"My interest is not the moon. To me the moon is as dull as a ball of concrete," says the astrobiologist. "But we're not going to have a research base on Mars until we can learn how to do it on the Moon first. The moon provides a blueprint to Mars."

A lunar base would provide a valuable opportunity to test out new propulsion systems, habitats, communications, and life support systems before astronauts bring them to Mars--a 9-month trip away, versus just a few days to the moon.

The trouble is, NASA tends to think it can only afford to go to either the moon, or Mars. If McKay and his colleagues are right, we can afford to do both--it just takes a new way of thinking about it.

There are other reasons to go back. We've explored only a tiny portion of the lunar surface, and a permanent base would certainly fuel some interesting science.

Plus, everyone else is doing it. China, Russia, and the European Space Agency have all expressed interest in setting up a base on the moon. Instead of getting left behind, cooperating with other nations on building a lunar station would lower NASA's costs, much like in building the International Space Station.

Private space companies are also ready and raring to go back to the moon. Many hope to extract water from the moon and split it into hydrogen and oxygen--i.e. rocket fuel--that can be used to top off the gas tanks of spacecraft headed for Mars. Lunar tourism could also become a hot market.

"And if private industry goes, NASA's going to go just to establish the rule of law," says McKay. "The fastest way to get NASA to the moon is to get other people to go."

How do we do it?

The exact strategy for building a lunar base differs depending on who you ask.

Many of the proposals start with robotic exploration to scope out the perfect site for a permanent dwelling. "MoonCats" (like a Bobcat, but adapted for lunar excavation) could then level the terrain for landing pads and the habitat,suggests one paper, while other robots set up solar power panels.

After the habitat modules arrive, robotic "Lunar Surface Mules" could help set them up so they'll be ready when the humans arrive.

Human occupation of the moon would likely begin slowly, with a few short stays by a small crew. The missions would get longer and larger over time, until you have a permanently occupied station, much like the International Space Station. Eventually the station could evolve into a complex, multi-use settlement with hundreds of people, and their children, living there permanently.

Some teams imagine the lunar station as a scientific base, while others picture it evolving into something more commercial.

"Some of the possible export options include: water from the permanently shadowed craters, precious metals from asteroid impact sites, and even [helium-3] that could fuel a pollution-free terrestrial civilization for many centuries,"writes one team. "As transportation to and from the Moon becomes more frequent and cheaper, the lunar tourism mark should begin to emerge and could become a significant source of income in the future."

What technologies do we need to survive?

At a basic level, we already know how to survive on the Moon, because humans have been living on the International Space Station for years.

"PLSS technologies have been proved in space for the past 14 years on the International Space Station,"writes one group, referring to the life support system that recycles the water on the space station and balances out the oxygen and carbon dioxide levels. "[W]e have access to sufficient life support technologies to support implementation of the first human settlement on the Moon today."

With those essentials taken care of, the team estimates that at today's launch prices, SpaceX could deliver the rest of the food and essential supplies for a crew of 10 for $350 million or less per year.

Other technologies could be adapted to lower the costs of a moon base. Virtual reality, for example, could aid in the planning efforts.

A lunar VR environment, incorporating the data sets knowledge bases, could be a powerful tool for prospecting, operational scenario development, and refinement of designs from various teams. A further integration of real world engineering software for thermal environmental testing, structures, CAD/CAM, additive manufacturing and 3D printing could be a template for building a Tony Stark style (the VR environment from the first Iron Man movie) prototyping environment that could greatly advance the design of a lunar development as well identifying and solving some of the problems before we get there.

3D printing could replace small components that break on the lunar station, shaving down launch costs.

The era of NASA's spinoff technologies may be coming to an end. Instead of developing highly specialized (and expensive) technologies for spaceflight that later turn out to be everyday products, everyday products could be adapted for spaceflight, says McKay. "One of my favorites is the Gates Foundation's Reinvent the Toilet Challenge." The program encourages new ways to clean human waste and recycle it into energy, clean water, and nutrients that could be used in farming.

"NASA could spend billions developing a space-rated toilet," says McKay, "or we could just buy the blue toilet developed by the Gates Foundation."

Many of the proposals for an affordable moon base rely on technologies that don't quite exist yet. But neither are they far from reality.

SpaceX's Falcon 9 rocket should be able to carry small payloads to the moon for a pretty good price, but it'll take a heavier rocket--such as the Falcon Heavy, set to debut later this year--to carry larger payloads, like lunar habitats, to the moon. Other strategies involve refueling rockets in orbit--a technique that's as yet untested.

Next generation technologies

Many of the proposals for an affordable moon base rely on technologies that don't quite exist yet. But neither are they far from reality.

SpaceX's Falcon 9 rocket should be able to carry small payloads to the moon for a pretty good price, but it'll take a heavier rocket--such as the Falcon Heavy, set to debut later this year--to carry larger payloads, like lunar habitats, to the moon. Other strategies involve refueling rockets in orbit--a technique that's as yet untested.

Bigelow Aerospace's inflatable habitat is a top contender for future moon lodgings. These flexible living modules could be folded up to fit in a rocket's cargo bay, then expand like a pop-up tent on the lunar surface. The company plans to launch a test version of the habitat to the International Space Station this year. However, the larger, pill-shaped "BA-330" modules won't launch until 2018. And since Bigelow is mainly focused on using these habitats to set up commercial space stations in Earth orbit, the design might have to be adapted to operate on the moon, where radiation levels are considerably higher.

Where should we live on the moon?

There are four fundamental things to consider when choosing real estate on the moon, according to one paper: power availability; communications; proximity to resources; and surface mobility.

The sun will likely be the primary source of power for future lunar stations. Trouble is, most places on the moon have "nights" that are 354 hours (about 15 days) long. That's a long time to rely on battery power. By comparison, the poles receive much more sunlight, with nights lasting closer to 100 hours (4 days). So the first lunar station will probably have to be at one of the poles.

Communications would be easier from the moon's near-side, which constantly faces Earth, compared to the poles, but a relay station on the moon or in orbit should provide a reliable connection.

And it's lucky the poles receive so much sunlight, because they're also expected to contain large amounts of frozen water in their deep, dark craters. That water could be extracted to provide water and oxygen to the lunar station, or to turn into rocket fuel for a profit.

And although the lunar north and the south poles receive similar amounts of light, the north pole came out ahead of the south in this survey because it has a smoother terrain that's easier to travel across.

In particular, the paper singles out the rim of Peary crater as being the top spot to develop a low-cost lunar station. Radar and remote sensing indicate it may contain water or other hydrogen-bearing molecules, and it has a relatively smooth floor, making it easier for robots to roll through its icy depths to extract resources.

Some upcoming missions--including NASA's Lunar Flashlight and IceCube aim to map the distribution of water on the moon, which could help to further refine the lunar real estate options.

How much would it cost?

Overall the consensus in these papers is that NASA could build a lunar base for $10 billion, with upkeep costs of about $2 billion or less per year, which is about as much as NASA puts toward the International Space Station every year. These are estimates that, with a little rearranging, could fit inside NASA's current budget.

And NASA wouldn't have to foot the bill alone.

"The cost is getting so low, maybe we don't even need to think of NASA doing it," says McKay. "It could be a private company."

A study from last year estimated that if water exists in large deposits on the moon, a base could pay for itself, generating $40 billion in rocket propellant per year.

What's more, such a base could potentially be up and running within the next decade.

Actually making it happen will certainly take longer than that, requiring political changes and technological developments. But McKay thinks the psychological barrier is the most significant.

"The biggest obstacle is getting everybody together, and getting a vision of a low-cost base as the starting point. If people think it's going to kill the budget, that just stops the conversation and brainstorming. If we can change the mindset, that starts the conversation and gets people thinking about how to make it a reality."

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NOW WATCH: Epic footage of SpaceX’s gutsy rocket landings

Astronaut Scott Kelly is back on American soil after an eventful year. 

Kelly spent 340 days aboard the International Space Station before making it back to Earth on Tuesday. During his time up there, he grew plants, conducted experiences, took breathtaking pictures and... grew two inches taller.

In large part, Kelly's year in space was meant to see how our bodies handle that much time in microgravity. One of the things that can happen? Astronauts aboard the ISS grow up to 3% taller, likely because the spine has a chance to elongate with less pressure from gravity.

But, unfortunately for Kelly's newfound height, the effect is only temporary. Once he's back on Earth for a long enough time, gravity will bring him back to his normal height. On Friday, NASA's ISS research group said it only took a few minutes for Kelly to go back to his original height:

 In 2013, NASA launched a study that wanted to figure out what it was that caused astronauts to elongate by focusing on the spine. There are still some ongoing studies on the topic.

Now that he's back, Kelly will be studied by scientists to look for other changes that may have happened to his body while in space, including any changes to his vision, bones, and brain. Knowing what happens to the body when it's in microgravity for a long time will give researchers clues for how they should prepare astronauts for even longer missions (like a trip to Mars, for instance). 

Watch Kelly arrive back to Houston, Texas:

RELATED: Mind-blowingly beautiful photos from Astronaut Scott Kelly's record-breaking year in space will make you fall in love with Earth all over again

SEE ALSO: An astronaut just returned to Earth after a record-breaking trip — and scientists can't wait to see him

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NOW WATCH: Watch astronaut Scott Kelly’s epic journey back to Earth in 60 seconds

The European Space Agency (ESA) launched its ExoMars spacecraft on March 14, 2016. The ESA hopes the rover onboard will find signs of life on Mars.

Produced by Zach Wasser. Video courtesy of Reuters/ESA.

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Paris - Europe and Russia are set to launch an unmanned spacecraft Monday to smell Mars' atmosphere for gassy evidence that life once existed on the Red Planet, or may do so still.

ExoMars 2016, the first of a two-phase Mars exploration, will see an orbiter hoisted from Kazakhstan at 0931 GMT Monday on a Russian Proton rocket.

With its suite of high-tech instruments, the Trace Gas Orbiter or TGO, should arrive at the Red Planet on October 19 after a journey of 496 million kilometers (308 million miles).

Its main mission to photograph the Red Planet and analyze its air, the TGO will also piggyback a Mars lander dubbed Schiaparelli.

"Rocket rollout — our #ExoMars 2016 mission is at the launch pad!" the European Space Agency (ESA) tweeted Friday.

ExoMars is a two-step collaboration between ESA and Russia's Roscosmos space agency.

The second phase, a Mars rover due for launch in 2018, seems likely to be delayed over money worries.

But the first phase is going ahead as planned, and with high expectations: "Determining whether Mars is 'alive' today", according to an ESA document.

A key goal is to analyze methane, a gas which on Earth is created in large part by living microbes, and traces of which were observed by previous Mars missions.

"TGO will be like a big nose in space," according to Jorge Vago, ExoMars project scientist.

Methane, the ESA said, is normally destroyed by ultraviolet radiation within a few hundred years, which implied that in Mars' case "it must still be produced today."

The question is: By what? 

Methane can either be generated in a biological process, such as microbes decomposing organic matter, or geological ones involving chemical processes in hot liquid water under the surface.

TGO will analyze Mars' methane in more detail than any previous mission, said ESA, to try and determine its likely origin.

 Anybody out there? 

Another key element of the ExoMars 2016 mission is Schiaparelli, named after a 19th century Italian astronomer whose discovery of "canals" on Mars caused people to believe, for a while, that there was intelligent life on our neighboring planet.

Schiaparelli is a "demonstrator" module to test heat shields and parachutes in preparation for a subsequent rover landing on Mars, a feat ESA said "remains a significant challenge".

During its few live days on the surface of Mars, Schiaparelli will also measure atmospheric particles, wind speed and temperatures.

The TGO's main science mission is scheduled to last until December 2017, but it has enough fuel to continue operations for years after, if all goes well.

As for the next phase, ESA director general Jan Woerner has mooted a possible two-year delay, saying in January: "We need some more money" due to cost increases.

The rover has been designed to drill up to two meters (2.2 yards) into the Red Planet in search of organic matter, a key indicator of life past or present.

Scientists widely accept that liquid water, an essential ingredient for life, once flowed on Mars.

Last September, researchers unveiled "the strongest evidence yet" the planet may still host water in the form of super-salty streaks of brine.

Today's Martian surface is considered too dry and radiation-blasted for living organisms to survive, but conditions would have been much more comfortable -- warmer and wetter -- some 3.5 billion years ago.

"Establishing whether life ever existed on Mars, even at a microbial level, remains one of the outstanding scientific questions of our time," said ESA, "and one that lies at the heart of the ExoMars programme".

The mission derives its name from the scientific term for the search for life beyond Earth — exobiology.

SEE ALSO: Eerie images of the ruins of America's Space Race will give you chills

MORE: NASA just released a jaw-dropping 360 degree photo that makes you feel like you're on Mars

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NOW WATCH: How NASA is revolutionizing our understanding of Mars

As if staring up at the night sky didn’t make us feel small already, astronomers have recently announced the discovery of the BOSS Great Wall, a group of superclusters that span roughly 1 billion light-years across and represents the largest structure ever found in space.

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

According to Joshua Sokol at New Scientist, the megastructure discovered by a team from the Canary Islands Institute of Astrophysics is composed of 830 separate galaxies and has a mass 10,000 times greater than the Milky Way. To put the scale of this structure into perspective, we orbit one single star, the Sun. Our galaxy, the Milky Way, has over 200 billion stars, just like our Sun, in it alone with an unknown amount of planets orbiting them.

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

However, not everyone agrees that the super structure should even be considered a structure at all. The argument is that these superclusters are not actually connected. Instead, they have dips and gaps between them that are sort of linked by clouds of gas and dust.

This loose connection causes a debate every time 'great wall-like' structures are found. In the end, the arguments seem to boil down to personal definitions of what constitutes a single structure with most researchers agreeing that they are one.

Despite the debate, the BOSS Great Wall is so far the largest object ever found in space. Even more mind-boggling is the fact that there are a lot of 'great walls' of superclusters floating around thousands and millions of light-years away.

Besides being straight-up awesome, the web of galaxies is also helping researchers better understand how the Universe was structured after the Big Bang. The crazy thing is that this newly found king of the skies will likely get dethroned in the very near future as our ability to see further and further into the Universe increases.

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NOW WATCH: Stunning new photos of the Milky Way give us the most detailed look of our galaxy yet

Way up in the constellation Cancer there's a 14th-magnitude speck of light you can claim in a 10-inch or larger telescope.

If you saw it, you might sniff at something so insignificant, yet it represents the final farewell of chewed up stars as their remains whirl down the throat of an 18 billion solar mass black hole, one of the most massive-known in the universe.

Astronomers know the object as OJ 287, a quasar that lies 3.5 billion light years from Earth. Quasars or quasi-stellar objects light up the centers of many remote galaxies.

If we could pull up for a closer look, we'd see a brilliant, flattened accretion disk composed of heated star-stuff spinning about the central black hole at extreme speeds.

As matter gets sucked down the hole, jets of hot plasma and energetic light shoot out perpendicular to the disk. And if we're so privileged that one of those jet happens to point directly at us, we call the quasar a "blazar". Variability of the light streaming from the heart of a blazar is so constant, the object practically flickers.

A recent observational campaign involving more than two dozen optical telescopes and NASA's space based SWIFT X-ray telescope allowed a team of astronomers to measure very accurately the rotational rate the black hole powering OJ 287 at one third the maximum spin rate — about 56,000 miles per second (90,000 kps) — allowed in General Relativity.

A careful analysis of these observations show that OJ 287 has produced close-to-periodic optical outbursts at intervals of approximately 12 years dating back to around 1891. A close inspection of newer data sets reveals the presence of double-peaks in these outbursts.

To explain the blazar's behavior, Prof. Mauri Valtonen of the University of Turku (Finland) and colleagues developed a model that beautifully explains the data if the quasar OJ 287 harbors not one but two unequal mass black holes — an 18 billion mass one orbited by a smaller black hole.

OJ 287 is visible due to the streaming of matter present in the accretion disk onto the largest black hole. The smaller black hole passes through the larger's accretion disk during its orbit, causing the disk material to briefly heat up to very high temperatures.

This heated material flows out from both sides of the accretion disk and radiates strongly for weeks, causing the double peak in brightness.

The orbit of the smaller black hole also precesses similarly to Mercury's orbit. This changes when and where the smaller black hole passes through the accretion disk.

After carefully observing eight outbursts of the black hole, the team was able to determine not only the black holes' masses but also the precession rate of the orbit. Based on Valtonen's model, the team predicted a flare in late November 2015, and it happened right on schedule.

The timing of this bright outburst allowed Valtonen and his co-workers to directly measure the rotation rate of the more massive black hole to be nearly 1/3 the speed of light. I've checked around and as far as I can tell, this would make it the fastest spinning object we know of in the universe. Getting dizzy yet?

CHECK OUT: The first discovery of 2 colliding black holes just fundamentally changed our perception of the universe

NOW READ: A groundbreaking first in astronomy found that black holes can be spotted with backyard telescopes

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NOW WATCH: A nearby black hole is doing something unexpected in the midst of a cataclysmic galaxy collision

Physicists in Switzerland are using new code called 'gevolution' together with Einstein's theory of general relativity to map the expansion of the early Universe more accurately than ever before.

The new model factors in the rotation of space-time and the amplitude of gravitational waves — the existence of which was confirmed just last month.

It's more accurate than previous software simulations, its developers say, because it takes into account the high-speed movements of particles and the fluctuations of dark energy.

In line with Einstein's general relativity theory, the aim was to predict the amplitude and impact of gravitational waves, and the unique rotation of space-time to map the growth of the Universe.

To achieve their target, the University of Geneva team analyzed a cubic portion in space, consisting of 60 billion zones, each containing a particle (a portion of a galaxy). This enabled them to study the way these particles moved in relation to their close neighbors.

By plugging in data from Einstein's equations, and using the UNIGE LATfield2 library and a Swiss supercomputer, the model could measure the metric of distances and time between two galaxies in the Universe.

Previously, scientists have studied the formation of large-scale cosmological structures using the gravitational law set down by Isaac Newton: that the attraction between two bodies is directly related to their mass and the distance between them.

While Einstein's general relativity theory has since superseded it, linking gravity with acceleration and providing a more accurate method of tracking a constantly changing Universe, the ideas set down by Newton are still extensively used to model the effects of gravity and large masses.

And that brings us back to the gevolution model, which is able to map the latest theories in scientific thinking and celestial movements against Newtonian codes.

What comes out the other end is a mathematical model that provides a more accurate and more complex look at how the Universe expanded at the beginning of its history – it should also help us understand more about gravitational waves and dark energy (thought to be responsible for up to 70 percent of the Universe).

"This conceptually clean approach is very general and can be applied to various settings where the Newtonian approximation fails or becomes inaccurate, ranging from simulations of models with dynamical dark energy or warm/hot dark matter to core collapse supernova explosions," explains the new paper,published in the journal Nature Physics.

The new code is also going to make it possible for the theory of general relativity to be tested on a larger scale than ever before, and to help foster further research, the team plans to make the gevolution code open to the public in the near future.

SEE ALSO: Most of the universe is missing — here are 5 ambitious experiments that might find the rest

MORE: 4 cosmic phenomena that travel faster than the speed of light

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NOW WATCH: Here's a 3-minute animation that will completely change the way you see the universe

On January 20th, 2016, researchers Konstantin Batygin and Michael E. Brown of Caltech announced that they had found evidence that hinted at the existence of a massive planet at the edge of the Solar System.

Based on mathematical modeling and computer simulations, they predicted that this planet would be a super-Earth, two to four times Earth’s size and 10 times as massive.

They also estimated that, given its distance and highly elliptical orbit, it would take 10,000 – 20,000 years to orbit the Sun.

Since that time, many researchers have responded with their own studies about the possible existence of this mysterious “Planet 9”.

One of the latest comes from the University of Arizona, where a research team from the Lunar and Planetary Laboratory have indicated that the extreme eccentricity of distant Kuiper Belt Objects (KBOs) might indicate that they crossed paths with a massive planet in the past.

For some time now, it has been understood that there are a few known KBOs who’s dynamics are different than those of other belt objects. Whereas most are significantly controlled by the gravity of the gas giants planets in their current orbits (particularly Neptune), certain members of the scattered disk population of the Kuiper Belt have unusually closely-spaced orbits.

When Batygin and Brown first announced their findings back in January, they indicated that these objects instead appeared to be highly clustered with respect to their perihelion positions and orbital planes. What’s more, their calculation showed that the odds of this being a chance occurrence were extremely low (they calculated a probability of 0.007%).

Instead, they theorized that it was a distant eccentric planet that was responsible for maintaining the orbits of these KBOs. In order to do this, the planet in question would have to be over ten times as massive as Earth, and have an orbit that lay roughly on the same plane (but with a perihelion oriented 180° away from those of the KBOs).

Such a planet not only offered an explanation for the presence of high-perihelionSedna-like objects – i.e. planetoids that have extremely eccentric orbits around the Sun. It would also help to explain where distant and highly inclined objects in the outer Solar System come from, since their origins have been unclear up until this point.

In a paper titled “Coralling a distant planet with extreme resonant Kuiper belt objects“, the University of Arizona research team – which included Professor Renu Malhotra, Dr. Kathryn Volk, and Xianyu Wang – looked at things from another angle. If in fact Planet 9 were crossing paths with certain high-eccentricity KBOs, they reasoned, it was a good bet that its orbit was in resonance with these objects.

To break it down, small bodies are ejected  from the Solar System all the time due to encounters with larger objects that perturb their orbits. In order to avoid being ejected, smaller bodies need to be protected by orbital resonances. While the smaller and larger objects may pass within each others’ orbital path, they are never close enough that they would able to exert a significant influence on each other.

This is how Pluto has remained a part of the Solar System, despite having an eccentric orbit that periodically cross Neptune’s path. Though Neptune and Pluto cross each others orbit, they are never close enough to each other that Neptune’s influence would force Pluto out of our Solar System. Using this same reasoning, they hypothesized that the KBOs examined by Batygin and Brown might be in an orbital resonance with the Planet 9.

As Dr.  Malhotra, Volk and Wang told Universe Today via email:

“The extreme Kuiper belt objects we investigate in our paper are distinct from the others because they all have very distant, very elliptical orbits, but their closest approach to the Sun isn’t really close enough for them to meaningfully interact with Neptune. So we have these six observed objects whose orbits are currently fairly unaffected by the known planets in our Solar System. But if there’s another, as yet unobserved planet located a few hundred AU from the Sun, these six objects would be affected by that planet.”

After examining the orbital periods of these six KBOs – Sedna, 2010 GB174, 2004 VN112, 2012 VP113, and 2013 GP136 – they concluded that a hypothetical planet with an orbital period of about 17,117 years (or a semimajor axis of about 665 AU), would have the necessary period ratios with these four objects. This would fall within the parameters estimated by Batygin and Brown for the planet’s orbital period (10,000 – 20,000 years).

Their analysis also offered suggestions as to what kind of resonance the planet has with the KBOs in question. Whereas Sedna’s orbital period would have a 3:2 resonance with the planet, 2010 GB174 would be in a 5:2 resonance, 2994 VN112 in a 3:1, 2004 VP113 in 4:1, and 2013 GP136 in 9:1. These sort of resonances are simply not likely without the presence of a larger planet.

“For a resonance to be dynamically meaningful in the outer Solar System, you need one of the objects to have enough mass to have a reasonably strong gravitational effect on the other,” said the research team. “The extreme Kuiper belt objects aren’t really massive enough to be in resonances with each other, but the fact that their orbital periods fall along simple ratios might mean that they each are in resonance with a massive, unseen object.”

But what is perhaps most exciting is that their findings could help to narrow the range of Planet 9’s possible location. Since each orbital resonance provides a geometric relationship between the bodies involved, the resonant configurations of these KBOs can help point astronomers to the right spot in our Solar System to find it.

But of course, Malhotra and her colleagues freely admit that several unknowns remain, and further observation and study is necessary before Planet 9 can be confirmed:

“There are a lot of uncertainties here. The orbits of these extreme Kuiper belt objects are not very well known because they move very slowly on the sky and we’ve only observed very small portions of their orbital motion. So their orbital periods might differ from the current estimates, which could make some of them not resonant with the hypothetical planet. It could also just be chance that the orbital periods of the objects are related; we haven’t observed very many of these types of objects, so we have a limited set of data to work with.”

Ultimately, astronomers and the rest of us will simply have to wait on further observations and calculations. But in the meantime, I think we can all agree that the possibility of a 9th Planet is certainly an intriguing one! For those who grew up thinking that the Solar System had nine planets, these past few years (where Pluto was demoted and that number fell to eight) have been hard to swallow.

But with the possible confirmation of this Super-Earth at the outer edge of the Solar System, that number could be pushed back up to nine soon enough!

Further Reading: arXiv.org

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After flying a space probe by Pluto for the first time last summer, NASA discovered an unusual "bite mark" feature on the surface.

Produced by Jenner Deal. Original Reporting by Jessica Orwig.

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Space is expensive.

To generate more power and more thrust, rockets need to carry more fuel, increasing the amount of weight the same rocket engine needs to lift.

It’s a vexing equation, which might explain why much of recent spaceflight is about putting objects into orbit, where they can earn their keep by relaying communications on the ground below.

Maybe what interplanetary travel needs is just a better engine to take people there.

Rosatom State Atomic Energy Corporation, Russia’s nuclear agency, thinks nuclear engines are just the ticket to get to Mars.

“A nuclear power unit makes it possible to reach Mars in a matter of one to one and a half months, providing capability for maneuvering and acceleration,” the head of Rosatom Sergey Kirienko told RT, a Russian state-owned media company.

“Today's engines can only reach Mars in a year and a half, without the possibility of return,” Kirienko said.

Rosatom says that that they expect to have a prototype engine ready for testing in 2018.

While both the RT story and the announcement from Rosatom are vague on specifics, it looks like it will be a thermal fission engine, like the ones that generate electricity in nuclear power plants. From Wired:

Nuclear thermal is but one flavor of nuclear propulsion. Rosatom did not respond to questions about their system’s specs, but its announcement hints at some sort of thermal fission. Which is to say, the engine would generate heat by splitting atoms and use that heat to burn hydrogen or some other chemical. Burning stuff goes one direction, spaceship goes the other.

NASA has contemplated similar engines for Mars missions. The biggest obstacle facing Russia is not the science of the engine, but the cost of developing it on Russia’s shoestring space budget. And then there’s also the small matter that if it doesn’t quite escape Earth’s gravitational pull, we’ll get a nuclear reactor crashing from space to Earth.

This article originally appeared on Popular Science.

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NOW WATCH: A robot was just sent to find life on Mars

There are a few places in the Universe that defy comprehension.

And supernovae have got to be the most extreme places you can imagine.

We’re talking about a star with potentially dozens of times the size and mass of our own Sun that violently dies in a fraction of a second.

Faster than it takes me to say the word supernova, a complete star collapses in on itself, creating a black hole, forming the denser elements in the Universe, and then exploding outward with the energy of millions or even billions of stars.

But not in all cases. In fact, supernovae come in different flavors, starting from different kinds of stars, ending up with different kinds of explosions, and producing different kinds of remnants.

There are two main types of supernovae, the Type I and the Type II. I know this sounds a little counter intuitive, but let’s start with the Type II first.

These are the supernovae produced when massive stars die.

We’ve done a whole show about that process, so if you want to watch it now, you can click here.

But here’s the shorter version.

Stars, as you know, convert hydrogen into fusion at their core. This reaction releases energy in the form of photons, and this light pressure pushes against the force of gravity trying to pull the star in on itself.

Our Sun, doesn’t have the mass to support fusion reactions with elements beyond hydrogen or helium. So once all the helium is used up, the fusion reactions stop and the Sun becomes a white dwarf and starts cooling down.

But if you have a star with 8-25 times the mass of the Sun, it can fuse heavier elements at its core. When it runs out of hydrogen, it switches to helium, and then carbon, neon, etc, all the way up the periodic table of elements. When it reaches iron, however, the fusion reaction takes more energy than it produces.

The outer layers of the star collapses inward in a fraction of a second, and then detonates as a Type II supernova. You’re left with an incredibly dense neutron star as a remnant.

But if the original star had more than about 25 times the mass of the Sun, the same core collapse happens. But the force of the material falling inward collapses the core into a black hole.

Extremely massive stars with more than 100 times the mass of the Sun just explode without a trace. In fact, shortly after the Big Bang, there were stars with hundreds, and maybe even thousands of times the mass of the Sun made of pure hydrogen and helium. These monsters would have lived very short lives, detonating with an incomprehensible amount of energy. 

Those are Type II. Type I are a little rarer, and are created when you have a very strange binary star situation. 

One star in the pair is a white dwarf, the long dead remnant of a main sequence star like our Sun. The companion can be any other type of star, like a red giant, main sequence star, or even another white dwarf.

What matters is that they’re close enough that the white dwarf can steal matter from its partner, and build it up like a smothering blanket of potential explosiveness. When the stolen amount reaches 1.4 times the mass of the Sun, the white dwarf explodes as a supernova and completely vaporizes.

Because of this 1.4 ratio, astronomers use Type Ia supernovae as “standard candles” to measure distances in the Universe. Since they know how much energy it detonated with, astronomers can calculate the distance to the explosion.

There are probably other, even more rare events that can trigger supernovae, and even more powerful hypernovae and gamma ray bursts. These probably involve collisions between stars, white dwarfs and even neutron stars.

As you’ve probably heard, physicists use particle accelerators to create more massive elements on the Periodic Table. Elements like ununseptium and ununtrium. It takes tremendous energy to create these elements in the first place, and they only last for a fraction of a second.

But in supernovae, these elements would be created, and many others. And we know there are no stable elements further up the periodic table because they’re not here today. A supernova is a far better matter cruncher than any particle accelerator we could ever imagine.

Next time you hear a story about a supernova, listen carefully for what kind of supernova it was: Type I or Type II. How much mass did the star have? That’ll help your imagination wrap your brain around this amazing event.

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NOW WATCH: NASA can't explain why an island on this mysterious moon has disappeared

Whenever someone strikes up a conversation with me about the universe, I get animated.

No surprise there: I've made a living writing about astronomy, physics, geology, spaceflight, and related areas of science for nearly a decade, and have read obsessively on these topics for much longer than that.

However, people have shared a lot of peculiar "facts" with me over the years that ended up being totally false.

Below are some of the silliest and most common claims I've heard.

No one is perfect — I believed many of these statements at some point in my life — but it's time to put these myths, misconceptions, and inaccuracies to rest. 

MYTH: The sun is yellow.

If you wince and look at the afternoon sun, it might look yellow — but the light it gives off is actually white in color.

The Earth's atmosphere between your eyes and the sun is what makes the star appear yellow.

The gases bend the light in an effect called Rayleigh scattering, which is what also makes the sky appear blue and causes sunsets to blaze into brilliant oranges and reds.

Not helping matters is that astronomers classify the sun as a main-sequence G-type star, or the misnomer "yellow dwarf."

Sources: NASA, NOAA, Washington University, University College London

MYTH: The Sahara is the biggest desert on Earth.

Not all deserts are hot and full of sand. They need only be dry and inhospitable.

Antarctica fits the bill, since it receives only two inches of precipitation a year and has few land animals.

At 5.4 million square miles compared to the Sahara's 3.6 million square miles, the Bottom of the World is a vastly larger desert.

Sources: USGS (1, 2), NASA, Encyclopedia of Earth (1, 2)

MYTH: Astrology can predict your personality or the future.

Wouldn't it be nice to get a glimpse of tomorrow based on something as simple as where the sun, planets, and moon were located when you were born?

That's what astrology claims to do, what 50% the world at least partly believes, and what as much as 2% of the planet strongly buys into.

Yet thorough scientific investigations of astrology have failed, again and again, to back up any predictions from an astrological sign or horoscope.

A 1985 study in Nature is especially notable. In that experiment, scientists used a non-biased, double-blind protocol and worked in conjunction with some of the top astrologers in the US to test the predictive power of astrological signs.

The results? The astrological predictions were no better than chance.

Sources: The Humanist, Comprehensive Psychology, Nature, Proceedings of the Biennial Meeting of the Philosophy of Science Association, Pseudoscience and Deception: The Smoke and Mirrors of Paranormal Claims,

If a huge fire breaks out in an orbiting spacecraft, what would happen?

Turns out NASA doesn't know. But they're going to find out by doing just that.

During the next International Space Station (ISS) resupply mission, NASA is going to intentionally spark a fire inside one of its unmanned resupply vehicles after its mission is complete. The purpose of this test is simply to "see what happens," writer Maddie Stone at Gizmodo reports.

Here's how NASA's Saffire-I fire experiment is going to go do down.

Once empty, NASA's Cygnus resupply container will undock from the ISS and propel itself to a sufficiently safe distance (about 4 hours away, according to Gizmodo) and on a different orbit from the ISS. Then NASA officials on the ground will remotely spark a fire inside a sealed, three-foot long box full of "cotton-fiberglass composite."

The fire is expected to burn for about 15 to 20 minutes, according to Gizmodo. Meanwhile, special temperature, carbon dioxide, and oxygen sensors will record the whole thing. A camera will also film the blaze, and heat sensors will gather data from both sides of the flame.

All of this data will then be tossed back to Earth inside Cygnus itself eight days later. That is assuming, of course, the spacecraft survives.

Astronauts have intentionally sparked small controlled fires in space before, but this is the first time NASA is attempting an experiment of this size.

Fire behaves differently in space than it does here on Earth. If you lit a match on Earth, the flame would be long and pointy because hot gases rise upward from the flame, keeping it straight and pointing up.

But in space, buoyancy does not exist, and the flame could spread out in all directions.

NASA scientists know that flames can be erratic in space, but they don't fully understand their properties and mechanics. That's because — up until now — experiments like this have been extremely dangerous. They've also (luckily!) never had a large fire on a spacecraft to learn from.

And while they have tested much smaller fires in space, they aren't enough to understand what would happen with a much larger one.

Read more about NASA's Saffire-I experiment here.

[h/t Gizmodo]

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NOW WATCH: NASA has built a 'wall of sound' to put its next spacecraft through hell

Nestled 250 million miles from Earth, between the orbits of Mars and Jupiter, is the largest object in the asteroid belt: Ceres.

It's home to some of the most puzzling features ever observed in our solar system, including a giant pyramid that dwarfs many mountains on Earth and several dazzling bright spots inside a 50-mile-wide crater.

Now, recent research, led by astronomers at the INAF-Trieste Astronomical Observatory in Italy, has discovered that these unique bright spots are doing something unexpected: They're changing.

And it could point to some of the most compelling evidence yet for a huge underground ocean sloshing beneath Ceres' rocky shell.

A misty glow

We first got a good look at Ceres and its perplexing landscape last year, when the Dawn spacecraft fell into orbit around it. But Dawn isn't the only instrument scientists are using to study Ceres.

Using the European Southern Observatory's 3.6-meter telescope, the team noticed that Ceres' spots appear to vary in brightness over time — growing brighter before dimming back down, like a lightning bug on a summer night.

Interestingly, the spots are brightest when they're on the day side of Ceres, facing the sun. This has led the team to suspect that these surprising changes are the result of sublimation, when a solid becomes a gas.

Heat from the sun's light sublimates certain materials, which then forms a visible misty haze above the spots, the team reported in the Monthly Notices of the Royal Astronomical Society.

When additional sunlight then strikes the mist, it scatters the light, giving off a brilliant glow that makes the spots appear brighter.

The mist, however, is only temporary. It seems to evaporate within a few hours after forming. Without any mist hanging over them, the spots then appear to dim, which explains the variable changes the team observed.

But there's one thing the mist doesn't explain: What's fueling it in the first place.

A grand ocean in space

Ceres has been around since the start of our solar system, which makes it roughly 4.6 billion years old.

If these spots have been shooting off mist for that long, then they should have disappeared by now, unless some source was continuously supplying the material.

So what's going on?

The team suspects that a vast underground ocean could be swelling up through cracks in Ceres' crust, which formed after a powerful impact.

"It is assumed that something comes out from [the] interior of the planet where there is a large amount of water and that can evaporate filling the crater and eventually dispersed under the action of solar radiation," the team said in a press release.

If there's liquid water underneath Ceres' surface, then that means that there must also be a heat source.

Ceres is turning out to be a far more interesting world than we thought.

SEE ALSO: NASA scientists can't explain this unusual 'bite mark' on Pluto's surface

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We have now become used to the discovery of new exoplanets, but there are still many unknowns that are yet to be understood.

An international team of astronomers set out to answer one of these unknowns:

What are the more favorable characteristics that stars need to have for the formation of giant planets?

In doing so, they have discovered four new exoplanets orbiting four different stars more massive than the Sun.

The team computed the radial velocity of 166 stars, and discovered four new planets around four of them: HIP95124b, HIP8541b, HIP74890b, and HIP84056b. The results were published in a paper accepted for publication in the journal Astronomy & Astrophysics.

HIP95124b has the shortest orbital period of the four planets (about 560 days) and has 2.9 Jupiter masses. It orbits a star that is almost twice as massive as the Sun and with five times its radius.

HIP8541b, on the other hand, is the one with the furthest orbit (about 1,560 days) and is the largest with a mass of 5.5 Jupiters. Its star is only slightly heavier than the Sun but almost eight times wider.

HIP74890b and HIP84056b are remarkably similar, orbiting stars about 1.7 times the mass of the Sun in about 820 days. Even their mass is pretty similar, 2.4 and 2.6 times the mass of Jupiter, respectively.

The scientists also found an interesting trend. They noticed that giant planets tend to be found more often around stars that are rich in elements like oxygen, carbon, and iron. As giant planets are not necessarily made by heavier elements, this might indicate the need for a rocky core for gas giants to form.

And they also discovered that intermediate mass stars, slightly bigger than the Sun, are more likely to host giant planets.

"We show that the fraction of giant planets increases with the stellar mass in the range between 1 to 2.1 solar masses, despite the fact that planets are more easily detected around less massive stars," the team wrote in the paper.

Although the study was conducted on a relatively small sample of stars, the findings might have a profound impact on our understanding of the Solar System. After all, our Sun has four giant planets.

READ MORE: Astronomers discovered unexpected activity on a giant asteroid that could point to something huge

SEE ALSO: NASA scientists can’t explain this unusual 270-mile-wide ‘bite mark’ on Pluto’s surface

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NOW WATCH: NASA can't explain why an island on this mysterious moon has disappeared

With NASA planning manned missions to Mars, attention has turned to growing food in space. Here's how a crew aboard the International Space Station grew space grown food for the very first time. 

Produced by Matt Stuart. Video courtesy NASA.

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