Saturday, 24 September 2016

Where will the out-of-control Chinese space station land?
Scientists have admitted that they have no way of safely guiding Tiangong-1 back to Earth, and say it is moving too fast to accurately predict where debris from the 8.5-tonne module will crash

What is happening with the Chinese space station?

The nation’s first prototype space station, Tiangong-1, or “Heavenly Palace”, launched into orbit in September 2011. The module reached the end of its service life earlier this year and was due to splashdown – eventually – in the Pacific Ocean. But at a recent press conference, the Chinese space agency admitted it had lost contact with the station. They did not explain what had gone wrong.

Does losing contact matter?

It depends what the Chinese planned to do next. If the agency was going to let the spacecraft simply fall to Earth in an uncontrolled way and burn up in the atmosphere, then the loss of contact means little. But if they had intended to perform a controlled de-orbit, that option is now gone. Controlled de-orbits tend to be reserved for spacecraft that pose a potential risk to people when they fall back to Earth. If the chances of someone being injured by components that survive the fireball of re-entry is greater than one in 10,000, then the spacecraft should be actively steered into a region of the South Pacific known in the business as the “spacecraft graveyard”. The module is already below the altitude of the International Space Station (ISS) and so there is no risk of a collision on its way down.

What was Tiangong-1 for?

Unlike the massive ISS, which is the size of a football field and has the living space of a five-bedroom house, Tiangong-1 is a mere 10 metres long and 3 metres wide. The Chinese used the module to practise rendezvous and docking procedures, and several taikonauts, including two women, spent time aboard after catching a ride on the Shenzhou spacecraft. Losing control of the module is more of an embarrassment to the Chinese space agency than a blow to their space programme. Two weeks ago, in a long-scheduled launch, the Chinese put another space station module, Tiangong-2, into orbit, and a crew of at least two taikonauts is expected to visit as early as next month. The agency still hopes to build a 55-tonne space station by 2020.

Will the stricken module survive re-entry?

Satellite tracking radar show the Chinese module at 380km high and travelling at 27,500km per hour. At that speed and altitude, it could lap the planet 5,000 more times before it starts to feel the drag of the upper atmosphere and begin its final descent. Most of the 8.5-tonne module will burn up from aerodynamic heating in the Earth’s atmosphere. But the Chinese space agency has conceded that some heat-resistant components may survive. “The module is predominantly a hollow shell, so there’s a good chance a significant portion will burn up in the atmosphere. But there’s also a chance some elements will survive down to surface,” said Hugh Lewis, a space debris expert at University of Southampton.

Where will it come down?

No one knows. And the vagaries of re-entry mean it will be impossible to predict with accuracy, even in its final moments. Computer simulations cannot tell far in advance on which orbit a spacecraft will re-enter. The Tiangong-1 is moving fast, at a shallow angle relative to the atmosphere, and the height of the atmosphere at any point depends on the regional temperature. But even when an object has begun its descent through the atmosphere, the final resting place of debris is still hard to predict. How the spacecraft tumbles through the atmosphere has an influence on how it breaks up. The most space agencies can do is calculate a debris ellipse where fragments are expected to land.

Are we in danger?

Pieces of space debris fall to Earth every day, but most of these are small fragments. Now and again, whole satellites or rocket stages tumble out of orbit and break apart in the sky. The most dangerous uncontrolled re-entry happened in 1979 when Nasa’s 85-tonne Skylab space station came down over Australia. In 2001, when the Russian Mir space station had reached the end of its life, Roscosmos de-orbited the 135-tonne outpost into the Pacific. But even with so much hardware raining from the skies, no one is known to have been hurt by falling space junk. “It is luck, but it proves that luck is on our side,” said Lewis. The odds are wildly in favour of not being hit because most of the Earth’s surface is covered with water, and most of the world’s population is crammed into a small percentage of land. The chances of a specific individual being struck by falling debris is trillions to one, making death by lightning far more likely.

Friday, 23 September 2016

Alien Planet Has 2 Suns Instead of 1, Hubble Telescope Reveals

An artist's illustration shows an exoplanet named OGLE-2007-BLG-349. It orbits a binary pair of red dwarf stars

Imagine looking up and seeing more than one sun in the sky. Astronomers have done just that, announcing today (Sept. 22) that they have spotted a planet orbiting two stars instead of one, as previously thought, using the Hubble Space Telescope.

Several planets that revolve around two, three or more stars are known to exist. But this is the first time astronomers have confirmed such a discovery of a so-called "circumbinary planet" by observing a natural phenomenon called gravitational microlensing, or the bending of light caused by strong gravity around objects in space. You can see how researchers found the planet in this video.

In binary-star systems, the two stars orbit a common center of mass. When one star passes in front of the other from our perspective on Earth, gravity from the closer star bends and magnifies the light coming from the star in the background. Astronomers can study this distorted light to find clues about the star in the foreground and any potential planets orbiting the star system.

The exoplanet in this study, named OGLE-2007-BLG-349, is located 8,000 light-years from Earth toward the center of the Milky Way. It was first spotted in 2007 by ground-based observations from telescopes around the world. At first, astronomers identified the system as a planet orbiting one star. Their data suggested that there was a third object, too, but the researchers weren't able to identify it at the time.

"The ground-based observations suggested two possible scenarios for the three-body system: a Saturn-mass planet orbiting a close binary star pair or a Saturn-mass and an Earth-mass planet orbiting a single star," David Bennett of NASA's Goddard Space Flight Center in Greenbelt, Maryland, and the paper's first author, said in a statement.

To get a better view, the team decided to use the Hubble Space Telescope, because space telescopes take better photos of deep space than land-based telescopes. Hubble's high-resolution images revealed that the system has the brightness expected of two closely orbiting red dwarf stars.

A two-planet, single-star model is not possible in this scenario, "because a two-planet model with a main sequence host would appear to be too bright to match the [Hubble Space Telescope] data, while a two-planet system orbiting a white dwarf would be too faint," the study's authors wrote in The Astronomical Journal.

"So, the model with two stars and one planet is the only one consistent with the Hubble data," Bennett said in the same statement. With Hubble now shown to be useful for identifying circumbinary exoplanets, the space telescope could become an important resource in the search for exoplanets.

Alien Planet Has 2 Suns Instead of 1, Hubble Telescope Reveals

An artist's illustration shows an exoplanet named OGLE-2007-BLG-349. It orbits a binary pair of red dwarf stars

Tuesday, 20 September 2016

What happened after the lights came on in the universe?

An experiment to explore the aftermath of cosmic dawn, when stars and galaxies first lit up the universe, has received nearly $10 million in funding from the National Science Foundation to expand its detector array in South Africa.

The experiment, an international collaboration called the Hydrogen Epoch of Reionization Array, or HERA, currently has 19 14-meter (42-foot) radio dishes aimed at the southern sky near Carnarvon, South Africa, and will soon up that to 37. The $9.5 million in new funding will allow the array to expand to 240 radio dishes by 2018.

Led by the University of California, Berkeley, HERA will explore the billion-year period after hydrogen gas collapsed into the first stars, perhaps 100 million years after the Big Bang, through the ignition of stars and galaxies throughout the universe. These first brilliant objects flooded the universe with ultraviolet light that split or ionized all the hydrogen atoms between galaxies into protons and electrons to create the universe we see today.

"The first galaxies lit up and started ionizing bubbles of gas around them, and soon these bubbles started percolating and intersecting and making bigger and bigger bubbles," said Aaron Parsons, a UC Berkeley associate professor of astronomy and principal investigator for HERA. "Eventually, they all intersected and you got this über bubble, leaving the universe as we observe it today: Between galaxies the gas is essentially all ionized."

That's the theory, anyway. HERA hopes for the first time to observe this key cosmic milestone and then map the evolution of reionization to about 1 billion years after the Big Bang.

"We have leaned a ton about the cosmology of our universe from studies of the cosmic microwave background, but those experiments are observing just the thin shell of light that was emitted from a bunch of protons and electrons that finally combined into neutral hydrogen 380,000 years after the Big Bang," he said. "We know from these experiments that the universe started out neutral, and we know that it ended ionized, and we are trying to map out how it transitioned between those two."

"Before the cosmic dawn, the universe glowed from the cosmic microwave background radiation, but there weren't stars lighting up the universe," said David DeBoer, a research astronomer in UC Berkeley's Radio Astronomy Laboratory. "At some point the neutral hydrogen seeded the stars and black holes and galaxies that relit the universe and led to the epoch of reionization."

The HERA array, which could eventually expand to 350 telescopes, consists of radio dishes staring fixedly upwards, measuring radiation originally emitted at a wavelength of 21 centimeters – the hyperfine transition in the hydrogen atom – that has been red-shifted by a factor of 10 or more since it was emitted some 13 billion years ago. The researchers hope to detect the boundaries between bubbles of ionized hydrogen – invisible to HERA – and the surrounding neutral or atomic hydrogen.

Monday, 19 September 2016

Chinese Space Station

Three Words: Chinese. Space. Station.

China just put another small space station into orbit—and by the 2020s they may replace the International Space Station. But private companies are the future of space exploration.

China has just launched its second small Tiangong space station into orbit, more or less catching up to what the United States’ and Russia’s own space programs achieved starting in the 1970s.
Riding atop a Long March rocket, the 34-foot-long, 10-ton Tiangong-2 blasted off from the Jiuquan Satellite Launch Center in northwest China on Sept. 15, aiming for an orbit 240 miles over Earth’s surface.
While Beijing’s effort to establish a long-term human presence in orbit is impressive on a political level, on a technological level it’s decades behind the curve. In the United States and elsewhere, private companies are poised to establish a long-term presence in space that doesn’t depend on big, government-run orbital structures.
“China is currently doing nothing in space that the U.S. hasn’t done already, much sooner, and often with a much higher level of technological sophistication,” Joan Johnson-Freese, a professor at the U.S. Naval War College and a space expert, told The Daily Beast.
In the race to build orbital habitations, Russia actually beat the United States by a few years when it launched the first of several Salyut stations beginning in 1971. America’s first space station was Skylab, which lasted six years starting in 1973. Today Russia and the United States work together on the International Space Station, which began operation in 1998 and has expanded to include dozens of modules capable of supporting six crew in total, year-round.
Compared to the International Space Station, the single-module Tiangong stations are tiny.
The plan is for a pair of Chinese astronauts to visit Tiangong-2 in October and stay for a month or so—an improvement over the Tiangong-1 station, which managed to support two crew for just eight days in 2012 and 12 days in 2013.
Tiangong-1, China’s first space station, launched in 2011 and decommissioned back in March amid rumors of a technical malfunction. Chances are the older station will plummet back to Earth sometime in 2017 as its orbit decays.
Like its predecessor, Tiangong-2 is supposed to last just a few years. Its replacement could be a third Tiangong station that, like Tiangong-1 and -2, will be temporary. The Chinese space agency is planning to loft a fourth and much larger station in 2020 or later. Assuming the project succeeds, the fourth craft could become the basis of a large, long-lasting space station similar in scale to the International Space Station.
But don’t hold your breath. “The Chinese have quite a bit more work to do before they are ready to start assembling their space station,” Gregory Kulacki, a space expert with the Union of Concerned Scientists, told The Daily Beast. “It is possible they could complete that work by 2020, but my guess is that they will need more time.”

In any event, it’s possible the Chinese could have a large, sustainable space station up and running by the time International Space Station finally reaches the end of the line in the mid- to late 2020s. At that point, prolonging the International Space Station’s useful life would take a sizable injection of expensive new technology requiring significant political will. With NASA’s budgets flattening and U.S.-Russian relations at a low point, the space station could begin to look like a pricey liability in Washington and Moscow.
And that’s where China holds an advantage. Sure, the Tiangong stations are small and somewhat archaic—and the larger station they’re meant to support will merely duplicate what the International Space Station achieved in 1998. What’s impressive is that Beijing has managed to plug away steadily at its space stations, year after year, calmly weathering economic crises and political turnover.
Such stability is vital for space programs costing tens or hundreds of billions of dollars and requiring years or even decades of research and development. And in space the Chinese Communist Party has proved remarkably stable. “As many members of the Chinese space community have told me, China is not in a hurry,” Kulacki explained. “They are not racing anyone, and safety is a higher priority than meeting an arbitrary deadline.”
Indeed, the enduring domestic political support for China’s space stations could prove more important than the stations themselves for China’s future as a space power. By contrast, the United States—and, to a lesser extent, other spacefaring countries—is virtually assuming that political will for its own space program will collapse, and private companies such as SpaceX, Blue Origin, and Virgin Galactic will fill the vacuum.
There’s even a company building space stations. In April, Las Vegas space startup Bigelow Aerospace announced an ambitious plan to build at least two inflatable space stations and lob them into orbit starting in 2020. The B330 stations—each featuring its own power, life-support systems, and maneuvering thrusters arranged around a central metal frame—could function as space hotels, orbital factories, and zero-gravity research labs.

CEO Robert Bigelow said he wants to attach the first B330 to the International Space Station in order to expand the station’s volume by as much as a third and, perhaps, help extend its usefulness beyond its planned mid-2020s decommissioning date. “We are hoping we can get the permissions necessary from NASA to say, ‘Yes, let’s attach it,’” Bigelow said.
But even if NASA says no, Bigelow said he will continue developing his inflatable stations. There’s plenty of incentive to do so. Asteroid- and moon-mining—and the associated orbital manufacturing—could mean hefty profits for any company willing to make a big investment in space technology andassume a significant financial risk.
“The new space players such as Bigelow, SpaceX, and Virgin Galactic are the future,” Johnson-Freese told The Daily Beast. “The new space players aren’t reliant on political will. They operate on business plans, a much sounder practice and one that will eventually ‘normalize’ space as an area of industrial and geographic development.”
While China tinkers with old school, government-funded orbital stations, the United States—via private enterprise—is laying the foundation for a whole new approach to space exploration.

Saturday, 17 September 2016

China’s atomic clock

China’s atomic clock in space will stay accurate for a billion years

China’s new space laboratory has an atomic clock which, Chinese engineers say, is more accurate than the best timepiece operated by America’s National Institute of Standards and Technology.

The device, called Cacs, or Cold Atomic Clock in Space, was launched this weak along with other instruments of the Tiangong-2, China’s second orbital lab. According to the South China Morning Post, it will slow down by only one second in a billion years. In comparison, the NIST-F2 atomic clock, which serves as the United States’ primary time and frequency standard, loses a second every 300 million years.
“It is the world’s first cold atomic clock to operate in space... it will have military and civilian applications,” said Professor Xu Zhen from the Shanghai Institute of Optics and Fine Mechanics, who was involved in the Cacs project.
An atomic clock uses vibrations of atoms to measure time, which are very consistent as long as the atoms are held at constant temperature. In fact, since 1967 the definition of second has been “9,192,631,770 vibrations of a cesium-133 atom.”
In a cold atomic clock, the atoms are cooled down with a laser to decrease the effect of atom movement on the measurements. Cacs goes even further and eliminates the pull of Earth’s gravity by being based in orbit.
Chinese engineers had to miniaturize their device so that it could be sent into space. It can fit in a car trunk, while the NIST-F2, along with all its support equipment, is about the size of a room.
Cacs was launched before the European Space Agency could place their atomic clock, the Pharao, in orbit, which is scheduled to be launched next year. The US abandoned a similar project due to budgetary cuts.
Unlike Pharao, which uses the traditional design with cesium atoms, the Chinese clock uses rubidium atoms. Developers say the element offers better performance in terms of accuracy and reliability.
Cacs is not the most accurate timepiece in the world. German researchers at Physikalisch-Technische Bundesanstalt have built an experimental atomic clock, which uses ytterbium ions and is two orders of magnitude more accurate than regular cesium clocks. The device, however, is used only for demonstration purposes, while Cacs is meant for practical applications.
The Chinese plan to improve their BeiDou Navigation Satellite System with synchronization signals from the new orbital atomic clock.

Thursday, 15 September 2016

Earth Vulnerable to Major Asteroid Strike

Earth Vulnerable to Major Asteroid Strike, White House Science Chief Says

Artist's concept of an asteroid striking Earth.

Credit: NASA/Don Davis

The world is still vulnerable to a potentially catastrophic asteroid strike, according to President Barack Obama's chief science adviser.

NASA has made substantial progress in finding the asteroids that pose the biggest threat to Earth, but there's still a lot of work to do, said John Holdren, director of the White House's Office of Science and Technology Policy.

"We are not fully prepared, but we are on a trajectory to get much more so," Holdren said today (Sept. 14) at NASA's Goddard Space Flight Center, during a discussion of the agency's planned Asteroid Redirect Mission (ARM). [Images: Potentially Dangerous Asteroids]

Holdren cited the February 2013 meteor explosion over the Russian city of Chelyabinsk and the 1908 Tunguska airburst as reasons to take the asteroid threat seriously.

The Chelyabinsk strike, which injured about 1,200 people, was caused by an object that is thought to be about 65 feet (20 meters) wide. The Tunguska event was much more powerful; a space rock perhaps 130 feet wide (40 m) exploded over a mostly unpopulated region of Siberia, flattening 800 square miles (2,070 square kilometers) of forest. Both strikes caught the world completely by surprise.

"We know that this does happen," Holdren said.

Strikes such as the Chelyabinsk impact are thought to happen once every hundred years, he added, while Tunguska is regarded as a once-in-1,000-years event.

But, Holdren said, "if we are going to be as capable a civilization as our technology allows, we need to be prepared for even those rare events, because they could do a lot of damage to the Earth."

"This is a hazard that, 65 million years ago, the dinosaurs succumbed to," he added. "We have to be smarter than the dinosaurs."

ARM can help educate us, Holdren said. In late 2021, NASA aims to launch a robotic probe toward a near-Earth asteroid; the current target is a 1,300-foot-wide (400 m) rock called 2008 EV5, but that’s not set in stone, agency officials said.

After it arrives at the asteroid, the spacecraft will pluck a boulder off its surface and then fly along with the space rock for a while, investigating the potential of a deflection strategy known as the "enhanced gravity tractor." (The standard gravity-tractor method calls for nudging a potentially hazardous asteroid off course over the course of years or decades, using the subtle gravitational tug of a tag-along robotic probe; this effect will be "enhanced" by the addition of the boulder's mass.)

The probe will then head back toward Earth, eventually placing the boulder in orbit around the moon. Astronauts aboard NASA's Orion space capsule will visit the purloined rock in the mid-2020s, agency officials have said.

The $1.25 billion ARM mission should help researchers learn more about asteroids and the resources they possess; demonstrate many of the technologies needed to get astronauts to Mars (which NASA aims to do before the end of the 2030s); help the agency practice human operations in deep space; and hone some of the skills that will be needed to deflect a potentially dangerous asteroid one day, Holdren said.

"The asteroid-retrieval mission makes sense in about five different ways," he said.

While smaller asteroids can do great damage on a local scale, experts think that space rocks must be at least 0.6 miles (1 km) wide or so to threaten human civilization. NASA scientists estimate that they have found at least 90 percent of these mountain-size, near-Earth asteroids, and none of them pose a threat for the foreseeable future.

Gravity tractors aren't the only possible defense against incoming asteroids. For example, dangerous space rocks could also be knocked off course by "kinetic impactors" (a series of spacecraft that slam into them). Some researchers have also proposed destroying asteroids with nuclear bombs; this is usually regarded as a last-resort strategy, to be used with space rocks that are discovered too late to deflect via gravity tractors and/or kinetic impactors.

Wednesday, 14 September 2016

China to launch second space laboratory

China to launch second space laboratory: report

China is pouring billions into its space programme and working to catch up with the US and Europe

China will launch its second space lab on Thursday, official media said Wednesday, as the Communist country works towards setting up its own space station, among several ambitious goals.

The Tiangong-2, or Heavenly Palace-2, will be sent into orbit from the Jiuquan Satellite Launch Centre in the Gobi desert, the official news agency Xinhua reported.
Engineers had begun injecting propellant into the Long March-2F rocket that would carry it aloft, it cited Wu Ping, deputy director of China's manned space engineering office, as saying.
Once it is in place the Shenzhou-11 mission will take two astronauts to the facility, where they will stay for 30 days, she added.
China is pouring billions into its space programme and working to catch up with the US and Europe.
It announced in April it aims to send a spacecraft "around 2020" to orbit Mars, land and deploy a rover to explore the surface.
Beijing sees the military-run programme as symbolising the country's progress and a marker of its rising global stature.
The nation's first lunar rover was launched in late 2013, and while it was beset by mechanical troubles it far outlived its expected lifespan, finally shutting down only last month.
But for the most part China has so far replicated activities that the US and Soviet Union pioneered decades ago.
It intends to build a Chinese space station, and eventually put one of its citizens on the surface of the moon.
China's first space lab, Tiangong-1, was launched in September 2011 and ended transmissions in March this year, when it had "comprehensively fulfilled its historical mission", Xinhua quoted Wu as saying.
It is expected to fall back to Earth in the second half of next year, she added

Tuesday, 13 September 2016

moon's birth

Moon's Birth May Have Vaporized Most of Earth, Study Shows

This artist's conception shows the giant impact that created Earth's moon. New research suggests the impact was powerful enough to vaporize a large portion of the young Earth.

Credit: Dana Berry/SwRI

The massive collision that created the moon may have vaporized most of the early Earth, according to a new analysis of samples collected during the Apollo moon missions.In the early days of planet formation, a grazing collision between the newborn Earth and a Mars-size rock named Theia (named after the mother of the moon in Greek myth) may have led to the birth of the moon, according to a prevailing hypothesis. Debris from the impact later coalesced into the moon. This "giant-impact hypothesis" seemed to explain many details about Earth and the moon, such as the large size of the moon compared with Earth and the rotation rates of the two bodies. But in the last 15 years, evidence has arisen that has challenged scientists to alter the details of this hypothesis. [How the Moon Evolved: A Timeline in Images]

Forming the moon

The moon is Earth's nearest

neighbor, but its origins date

back to a violent birth billions

of years ago. See how the

moon was made in this

Space.com infographic.

Credit: By Karl Tate, Infographics Artist

In 2001, scientists began discovering that terrestrial and lunar rocks had a lot in common: the two bodies possess many of the same chemical isotopes. (Isotopes of an element have different numbers of neutrons from each other. These subvarieties are identified by different numbers; for example, potassium-39 or potassium-40). Isotopes can act as geologic fingerprints, because prior work has suggested that planetary bodies that formed in different parts of the solar system generally have different isotopic compositions. These discoveries threw the giant-impact hypothesis into crisis because previous computer simulations of the collision predicted that 60 to 80 percent of the material that coalesced into the moon came from Theia rather than Earth. The likelihood that Theia happened to have virtually the same isotopic composition as Earth seemed extremely unlikely.At first, scientists thought more precise isotopic analyses might help resolve this "isotopic crisis." However, more accurate measurements of oxygen isotopes reported in 2016 only helped confirm this problem, said study lead author Kun Wang, a geochemist now at Washington University in St. Louis.
"Now we need to rethink the ideas that we had about the giant impact," Wang told Space.com. New ideasNew models of the giant impact seek to explain how the moon could have formed from mostly the same material that makes up the Earth, rather than mostly from Theia.
"There are many new models — everyone is trying to come up with one — but two have been very influential," Wang said in a statement. [How the Moon Formed: 5 Wild Lunar Theories]

A diagram showing two recent models for how

the moon formed from a collision between

the early Earth and another massive body.

One model (top) allows for an exchange

of material between the Earth and the

moon through a silicate atmosphere,

while the other model creates a more

thoroughly mixed sphere of a supercritical

fluid (bottom). Each of these models

leads to a different prediction for

potassium isotope ratios in lunar

and terrestrial rocks (right).
Credit: Kun Wang

The original giant-impact model suggested that a relatively low-energy collision melted part of Earth and the whole of Theia, flinging some of the molten debris outward. One relatively new model, proposed in 2007, starts with a low-energy impact just like the original model, but adds an atmosphere of silicate vapor around Earth and the disk of debris that ends up forming the moon. This model suggests that this vapor shroud helps Earth and the disk exchange material before the moon emerges from the debris.

One drawback of this low-energy impact model is that it would take a long time to exchange material through an atmosphere, Wang said. This scenario would make it difficult to achieve the mix of material seen in terrestrial and lunar rocks, he said.

Another model, proposed in 2015, suggests that a high-energy impact created the moon, one so violent that it vaporized Theia as well as most of Earth, including the young planet's mantle region (the layer just above the core). This dense vapor then formed an atmosphere that filled a space more than 500 times bigger than today's Earth. Much of this material would fall back onto the Earth as it cooled, but in addition, some of the debris formed the moon.

In this high-energy model, the atmosphere would behave like a "supercritical fluid," without a distinct separation between liquids and gases. Material could mix thoroughly in such an atmosphere, which could help explain the identical isotopic compositions of Earth and the moon, Wang said.

To see which model might best explain how the moon formed, Wang and his colleague Stein Jacobsen at Harvard University focused on potassium isotope data from terrestrial rocks and lunar samples gathered during the Apollo missions. Potassium is volatile, or easy to evaporate, and previous research suggested that analyzing potassium isotopes could shed light on the conditions during the event that formed the moon.

The scientists analyzed seven moon rocks collected during the Apollo 11, 12, 14 and 16 missions. They compared their potassium isotope ratios with those of eight rocks representative of Earth's mantle.

The researchers developed a method to analyze potassium isotopes with a level of precision 10 times better than the best previous technique. Potassium has three stable isotopes, but only two of them, potassium-39 and potassium-41, are abundant enough to be measured with sufficient precision for this research.

The scientists discovered that lunar rocks were richer by about 0.4 parts per thousand compared with Earth rocks when it came to potassium-41, the heavier stable isotope of potassium.

These findings support the high-energy impact model, which predicted that lunar rocks would possess more of the heavier isotope than terrestrial rocks. In contrast, the low-energy impact model suggested that lunar rocks would contain less of the heavier isotope.

The best explanation for how the heavier isotope came to dominate was that the moon condensed in a cloud with a pressure of more than 10 bar, or about 10 times the atmospheric pressure on Earth at sea level.

"I'm kind of surprised that the new model fits the data the best," Wang said. Still, "we had no expectation which model we were going to support," he said.

Future research should conduct follow-up studies to test these new findings. "We're definitely hoping more people will follow up and try to confirm our results," Wang said.

Wang and Jacobsen detailed their findings online Sept. 12 in the journal Nature.

Monday, 12 September 2016

Exoplanets

How Space Scientists Turn Exoplanets Into Places We Can ‘See’

Artist’s impression showing the plant Proxima b orbiting the red dwarf star Proxima Centauri, the closest star to the Solar System.

DO A GOOGLE image search for “exoplanet.” You’ll find awesome stuff: golden worlds like almond cookies, outsized maroon crags, marbly surfaces, hyperclose suns, clouds obscuring unfamiliar continents.

On August 24, astronomers got a new planet to make pictures of: one orbiting the nearest star to our solar system, Proxima Centauri. The planet, Proxima b, orbits closely enough that its water might not be frozen (if it has water) and far enough away that it may not have baked off (maybe). The European Space Agency shared a surface view of a suns-set on Proxima b, with three stars near the horizon illuminating jutting rocks, rounded rocks, arcing rocks, and possibly some fog in the foreground.

Of course, scientists don’t actually know what any exoplanets look like. But imagining how they might be—in a standing-right-there sense—is central to scientists’ perceptions of and interest in them, according to Lisa Messeri, a space anthropologist at the University of Virginia. And people feltso passionate about Proxima b (which is not Earth-like) because its proximity makes it more real. It is a place people could imagine being.

Messeri studies how scientists effect the transformation from random planet to real place. In her new book, Placing Outer Space, she maps that mental shift among scientists at the Mars Desert Research Station, at a Silicon Valley NASA center, at a mountaintop observatory in Chile, and in an MIT exoplanet group.

Messeri immersed herself in that latter cohort during her third year as a doctoral student at MIT , when she met professor Sara Seager. Seager is a celebrity scientist now, profiled by the likes of Cosmo. But back when she met Messeri, around 2009, she was mostly a rock star among scientists. Seager took Messeri into her research group for nine months, letting her orbit, observe, ask questions.

“The first thing you notice when you’re really spending time with exoplanet astronomers is just how little data there actually was to model and play with,” says Messeri. That was especially true when her work began, before Kepler’s heyday. For Seager and her students, a “planet” emerged from just a few data points showing how a star’s brightness changed over time. A dip in the middle showed the star’s light dimming, suggesting an alien globe had passed in front of the star. Over time, Seager and her students learned to see a whole world in that upside-down-omega shape. “That line,” says Messeri, “becomes incredibly evocative.”

They could learn a planet’s radius, the length of its year, its distance from its star. They could infer fuzzy things about its composition, its temperature. They could start to picture the planet, almost as if joining the flat parts of that upside-down-omega at the top to make a circle.
Home Sweet Home

It’s easy enough to imagine an exoplanet—and imagine yourself on it, arm draped against your forehead to shield your eyes from the three suns—that’s “like Earth.” When a scientist finds an Earth-sized or Earth-mass planet, their wild imagination has familiar places to run: variations on the theme of “Earth.” It’s got some water, maybe some Truffula trees, some canyons grander than our planet’s. It’s great!

But what about all those planets very much not like Earth (a category also known as “most”)? “With alien and exotic exoplanets, it struck me as a real puzzle,” says Messeri. “Scientists still manage to take worlds that are zipping around their sun every four days, gas giants larger than Jupiter, planets with molten surfaces with only one side facing their sun and understand that this is what they’re like. And how did it get transformed into a world?”

Part of the key is in the language Messeri herself used in that last sentence: A four-day year is tiny only in reference to ours. She compares huge gas planets to smaller Jupiter. She says planets face and zip around their suns.

It’s all about bringing it back home. We have hot Jupiters, mini-Neptunes, super-Earths. All of these planet categories, by their very definitions, are not like Jupiter, not like Neptune, not like Earth. But to construct a place, scientists have to draw on the worlds within their own experience: and My Very Educated Mother Just Served Us Nine is all we’ve got.

In the book, Messeri cites a paper Seager’s group was writing about the planet GJ 1214b. They explicitly said the planet had no analogs within our solar system. And yet, “each time they tried to get away from solar system analogies, it became apparent that analogy was the only way out of the semantic gap.”

Astronomers have created these comparison terms to conceptualize planets, yes. But the terms also shape the way the astronomical community perceives their discoveries. Researchers must get the people who read their papers—including the reviewers who decide whether a paper gets published at all—to see the same interesting and extant world they see in the data. A little linguistic push in the right direction never hurts.

A NASA Goddard scientist, for instance, told Messeri about a colleague who had theorized a new kind of world: the “volatile-rich planet,” Earth-mass but smothered in liquid. A competitor had come up with the same idea around the same time. But he called them “ocean-planets” in his paper. That second guy—people paid attention to him. People can picture an ocean. They can’t call up a volatile. “You have to make the argument not just that this is a planet but that this is a place worth studying,” says Messeri.

In some ways, then, exoplanet science is world-building of the persuasive variety.
Earth’s Origins

And I’ve been doing it myself this whole piece. Even the word “worlds” is meant to make you think of these spheroids of solid, liquid, and gas in a certain way. I could relentlessly call them “exoplanets,” but that puts a telescope lens between you and them. I could stick to “planets,” which would connect them to the shapes in our solar system.

But “world”: That’s a thing you are (or some other species is) meant to exist on, a thing of the same sort that we exist on. Or, as Messeri wrote more eloquently, it “connotes an inextricable linking between Earth and humanity.”

Of course, we didn’t always think of our own planet as being like all the other ones. It was only after Voyager sent back the image of Earth as a Pale Blue Dot, after astronauts started going up regularly, and especially after they got social media accounts that humans conceived of Earth as a globe in space (and still, actually feeling that this is actually a planet shaped like a planet requires concentration).

Earth has always been a place to us. It’s always been our world. But it’s only recently become our planet.

Today, says Messeri, a new shift is taking place. The image of the Pale Blue Dot at first made humans feel speckish, alone, insignificant. But exoplanet astronomers spend their lives searching for other Pale Blue Dots. And their work has shown us that the universe is teeming with dots, be they quite as blue as ours or not.

And as astronomers gather the data that turns those dots into imaginable planets, the universe begins to feel more friendly and knowable, full of places we can picture.

Sunday, 11 September 2016

Why we turn inanimate spacecraft into lovable explorers

'Cuteness culture' in space: Why we turn inanimate spacecraft into lovable explorers

Philae lander, OSIRIS-REx, Mars Curiosity Rover all have personalities and sometimes, even genders

NASA's Curiosity Mars rover was never assigned a gender, but it has a big personality, tweeting excitedly about its discoveries on the red planet. (NASA/JPL-Caltech/MSSS

They have names and personalities, they go on exciting journeys, and we're sad when they die. And we even create social media accounts just for them.Much like we do with pets, we often assign human characteristics to spacecraft.NASA's Mars Phoenix lander and Curiosity rover, and the European Space Agency's Philae lander and Rosetta spacecraft all cheerfully tweeted their progress as they carried out their missions, to the delight of thousands of fans online.The way we talk about inanimate spacecraft is part of the rise of "cuteness culture," that has been growing since the early 90s, much like the internet's fascination with cat videos, said Teresa Heffernan, an English professor at Saint Mary's University in Halifax.

The Philae lander, seen separating from the Rosetta spacecraft in this animation. The European Space Agency has already permanently ditched the lander on a comet, and the Rosetta will soon follow. (ESA/ATG medialab)

"It appeals to this world that's gentle, that's safe, that's childlike, and you have this warm feeling about the technology," said Heffernan.This can make the science behind the missions more accessible, but it can also distract from the bigger questions behind space exploration. And sometimes, it can encourage stereotypical gender roles.

'w00t!!! Best day ever!!'

One of NASA's first Twitter accounts was for the Mars Phoenix lander mission. The robot was given a fun-loving, adventurous personality.When the lander discovered ice on Mars, NASA broke the news via the account, using the internet-speak of the day."It was one of the most popular Twitter accounts at the time, and it was really in the infancy of Twitter," said John Yembrick, the social media manager for NASA.He said NASA's social media mantra is to make people care about what they do."NASA is sometimes viewed as complex science or engineering and what we want to do is tell a story to people and try to make things accessible," he said.They write in plain language, relate to popular culture when they can, and use storytelling to attract and dazzle.It's an attempt to connect with people in a personal way, said Christine Hoekenga, who's in charge of the social media account for NASA's

OSIRIS-REx mission, which launched Thursday night.

"Hopefully people hear it as a voice and can start to imagine a spacecraft as an explorer who's really out there in space, trying to help answer some of the big questions that we are all wondering about," she said.People engage with these crafts and probes, watching along as they carry out their missions. The spacecraft 'talk' to each other, too."Those tend to be very popular posts," said Hoekenga. "That's a flag that people are absorbing this information … and hopefully people are clicking through to get a little more information about each mission."When its lifespan ends, they often (somewhat morbidly) tweet their own 'deaths'.This tendency to humanize is natural, said Beatrice Priest, a cultural historian at the University of Cambridge in Cambridge, U.K."Stories are everywhere around us in the world. They are how we imagine and interpret the world and the scenarios we face. We are also encouraged from childhood to anthropomorphize inanimate objects. I think that the treatment of spacecraft is an extension of this," she said.

Distracts from complicated issues

This kind of behaviour may be endearing, and beneficial for outreach.Hoekenga and Yambrich from NASA don't see a downside, other than occasionally making some people sad when a spacecraft 'dies.'But Heffernan says it's distracting."I'm not opposed to technology or space exploration, but I think that by encompassing it with this kind of cuteness, it's distracting us from some of the more complicated issues," she said.These issues range from the cost of space exploration, the ethical and practical issues that arise from the concept of colonizing Mars, and environmental concerns like the creation of trash in space (the ESA, for example, has ditched the Philae on a comet forever, and the Rosetta will soon follow).

NASA's latest mission, the OSIRIS-REx, was named after a male Egyptian god and thus has been given a male gender identity. (NASA)

"We should have a discussion about these issues as a society rather than reducing it to this kind of childlike thing," she said.Heffernan called this a kind of propaganda for space exploration, saying it makes these spacecraft seem non-threatening and less destructive than they may actually be.

Gender concerns

Very often, spacecraft and probes are assigned a gender."He is an explorer at heart," said Hoekenga of the OSIRIS-REx. "He loves asteroids and space and science, but he also is kind of a renaissance spacecraft because he likes art and literature and pop culture and even sports."She said it was designated male because of the name, which comes from a male Egyptian god.
The Rosetta spacecraft and its accompanying probe, the Philae lander, were also given genders.
"Philae was represented as a little boy who was going on an adventure and Rosetta was presented like a mother figure who was there to help him," said Kathleen Richardson, who researches the ethics of robotics atDe Montfort University in Leicester, U.K.
But #notallspacecraft; Yembrick pointed out that the Mars Curiosity rover was never a ''he' or a 'she.'
Even so, gendering is common. Richardson said this reinforces traditional stereotypes that males are adventurous and brave, while women are nurturing and caring.
It's an object, but now you've started to represent it through gender roles," she said. "It just reflects the power structures that are present in our society and deeply embedded into our psyche."

NASA's Orion Space Capsule on Course for 2018 Trip Around the Moon

Technicians at NASA’s Kennedy Space Center work to get the Orion crew capsule ready for an unmanned trip around the moon in 2018. Photo taken Sept. 8, 2016.

Credit: Mike Wall, Space.com

CAPE CANAVERAL, Fla. — NASA's next-generation crew-carrying spacecraft remains on track to make a historic journey around the moon in 2018, agency officials say.

The bulk structure of the Orion capsule that will be used for that uncrewed test flight, which is known as Exploration Mission-1 (EM-1), is now mostly complete, NASA officials said. Engineers and technicians have moved on to installing critical systems — for example, welding together the metal tubes that make up the spacecraft's propellant and other fluid lines.

This work is being done inside a large clean room at the Neil Armstrong Operations and Checkout Building here at NASA's Kennedy Space Center (KSC). [The Orion Space Capsule: NASA's Next Spaceship (Photos)]

"It's a very clean environment," Scott Wilson, NASA manager of production operations for the Orion Program, said during a media tour Thursday (Sept. 8).

"We need that for the reliability of the valves and things that have to work on the vehicle, as well as propulsion — fuel and oxidizers," he added. "If you have contaminants, it could cause contamination to stick valves or cause fires, that kind of thing."

A view of the clean room at NASA’s Kennedy Space Center where the Orion capsule is being readied for a 2018 test flight around the moon. Photo taken Sept. 8, 2016.

Credit: Mike Wall, Space.com

The KSC team will wrap up their work with Orion in February or March of 2018, said Jules Schneider, Orion KSC operations manager with Lockheed Martin, NASA's prime contractor for the vehicle. The space agency will then work to prep Orion for EM-1, which is currently scheduled to lift off in October or November 2018.

EM-1 will mark the maiden flight of the Space Launch System (SLS), the huge rocket NASA is developing to blast astronauts toward Mars and other distant destinations. On EM-1, SLS will send Orion on a three-week flight around the moon designed to test the capsule's performance in deep space.

"We really want to run Orion through its paces and stress those systems as much as we can in an uncrewed configuration to make sure we've got the design and the ability to build the vehicles properly before we put crew on it," Wilson said.

Orion has flown to space once before. In December 2014, the capsule launched on an uncrewed 4-hour orbital jaunt known as Exploration Flight Test-1 (EFT-1). (EM-1 will use a new Orion vehicle.)

Astronauts will ride aboard Orion for the first time on Exploration Mission-2 (EM-2), which NASA has said will take place no later than 2023. But the agency is working to get EM-2 off the ground in 2021, Wilson said.

"We're committed to 2021, and we're on track for that," he said.

Friday, 9 September 2016

Atlas 5 launches NASA asteroid sample return mission

An Atlas 5 launches NASA's OSIRIS-REx asteroid sample return spacecraft from Cape Canaveral on Sept. 8. Credit: SpaceNews/Jeff Foust

KENNEDY SPACE CENTER, Fla. — An Atlas 5 successfully launched a NASA mission to visit a near Earth asteroid and return samples of it to Earth Sept. 8.

The United Launch Alliance Atlas 5 411 lifted off at 7:05 p.m. Eastern from Space Launch Complex 41 at Cape Canaveral, Florida. No significant problems were reported during the countdown, and weather remained favorable throughout the day leading up to launch.

The Atlas 5 launched NASA’s Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer, or OSIRIS-REx, spacecraft. The spacecraft separated from the Atlas nearly one hour after liftoff.

“This was an excellent launch,” said Tim Dunn, NASA launch manager, after spacecraft separation. “Not a single anomaly was worked during the countdown. That’s almost unheard of.”

Initial operations of the spacecraft, including deployment of its solar arrays and initial communications with NASA’s Deep Space Network, also went as planned. “The OSIRIS-REx spacecraft is happy and healthy,” said Rich Kuhns, OSIRIS-REx program manager for Lockheed Martin, at a post-launch press conference. “It is working absolutely as we designed it.”

OSIRIS-REx is the third mission in NASA’s New Frontiers program of medium-sized planetary missions, with an estimated cost of $800 million plus launch and operations. Lockheed Martin built the spacecraft using hardware designs derived from a number of previous planetary missions.

The spacecraft will travel to Bennu, a near Earth asteroid about 500 meters in diameter, arriving there in in August 2018. The spacecraft will study the asteroid for nearly two years before making brief contact with the asteroid’s surface to collect samples of dust and rock.

A collection device, known as the Touch-and-Go Sample Acquisition Mechanism (TAGSAM), will use puffs of nitrogen gas to agitate the surface, collecting material in filters. TAGSAM is designed to collect at least 60 grams of material, but project officials are confident it can collect much more, perhaps up to 2 kilograms.

The spacecraft will deposit the samples collected by TAGSAM into a sample return canister based on the same design used for the Stardust comet dust sample return mission. Collection of the sample will mark the end of the science phase of the mission as the spacecraft moves to a safe distance from the asteroid.

“It’s all about keeping that precious sample safe, doing nothing that can possibly jeopardize it,” said Jason Dworkin, OSIRIS-REx project scientist at NASA’s Goddard Space Flight Center, at a Sept. 6 briefing.

OSIRIS-REx will depart from Bennu in March 2021 and return to Earth two and ahalf years later. The sample return canister will parachute to a landing in the Utah Test and Training Range on Sept. 24, 2023.

Dante Lauretta, the University of Arizona planetary scientist who is the principal investigator for OSIRIS-REx, said at a pre-launch press conference Sept. 6 that he was eager to get the mission started, having worked on the concept for more than a decade. “I am anxious, because I’ve been working on this program for 12 years now and I really want to fly this spacecraft,” he said.

After the launch, he felt relieved. “We hit all of our milestones within seconds,” he said at a post-launch press conference. “We really kicked that field goal right down the center.”

The launch is a highlight in a busy year for NASA’s New Frontiers program. On July 4, the second New Frontiers mission, Juno, entered orbit around Jupiter nearly five years after launch. Juno completed its first orbit around Jupiter Aug. 27 and will enter its primary science orbit in October.

A few days before Juno’s arrival, NASA formally extended the mission for New Horizons, the first New Frontiers mission, which flew past the dwarf planet Pluto in July 2015. The mission extension will allow New Horizons to fly past a small body in the distant Kuiper Belt in January 2019.

NASA is also preparing for the competition for the fourth New Frontiers mission. NASA issued a draft announcement of opportunity for the competition in August for comment, and plans to issue the final announcement in January 2017. NASA expects to select a mission in May 2019 for launch in 2024 or 2025.