Category: Deep Space

Enceladus’s subsurface ocean harbors complex organic molecules

Saturn moon is now the only solar system location other than Earth to meet all requirements for microbial life.

Analysis of mass spectroscopy data returned by NASA’s Cassini spacecraft indicates Saturn’s moon Enceladus harbors complex organic molecules in its subsurface ocean, which are ejected through cracks in surface ice.

Cassini made several close flybys of Enceladus, one of the solar system’s top contenders for hosting microbial life, before the spacecraft was plunged into Saturn in September 2017. These flybys found evidence for a subsurface ocean above the moon’s rocky core and detected molecular hydrogen in plumes coming from that ocean.

Scientists believe molecular hydrogen is produced by geochemical interactions between water and rocks in hydrothermal environments, according to a paper on the findings published in the journal Nature.

“Hydrogen provides a source of chemical energy supporting microbes that live in the Earth’s oceans near hydrothermal vents. Once you have identified a potential food source for microbes, the next question to ask is, ‘what is the nature of the complex organics in the ocean?’ This paper represents the first step in that understanding–complexity in the organic chemistry beyond our expectations!” stated Hunter Waite of the Southwest Research Institute (SwRI), who served as principal investigator for Cassini’s Ion and Neutral Mass Spectrometer (INMS).

Both INMS and Cassini’s Cosmic Dust Analyzer (CDA) measured the contents of Enceladus’s plumes and of material in Saturn’s E ring, which is composed of ice grains from those plumes.

“Previously, we’d only identified the simplest organic molecules containing a few carbon atoms, but even that was intriguing,” Christoper Glenn, also of SwRI and a specialist in extraterrestrial chemical oceanography, noted. “Now, we’ve found organic molecules with masses above 200 atomic mass units. That’s over 10 times heavier than methane.  With complex organic molecules emanating from its liquid water ocean, this moon is the only body besides Earth known to simultaneously satisfy all of the basic requirements for life as we know it.”

By working together, each with their own data set, the CDA and INMS teams achieved a better understanding of the organic chemistry in Enceladus’s ocean than either of the teams would have done with just their own data set, Glenn noted.

In their paper, the researchers recommend a future mission fly through Enceladus’s plumes and use a high-resolution mass spectrometer to analyze the complex organic molecules, with the goal of learning the process by which they formed.

 

Humans likely alone in universe, study reports

A new study shows that humans are likely the only intelligent life in the observable universe.

A team of international researchers have found evidence that humans are the only intelligent life in the known universe, according to a new study published online.

For the research, the team analyzed the so-called Fermi paradox that shows, while there are millions of celestial bodies throughout the cosmos, there is no concrete evidence of alien life. 

They broke down the equation initially proposed by Frank Drake in the 1960’s that states the vast size of the universe inherently suggests other intelligent life must exist.

However, when the team behind the recent study incorporated new elements into the equation they found it is open to both uncertainties and bias. As a result, it is likely not as accurate as previously believed.

“When the model is recast to represent realistic distributions of uncertainty, we find a substantial ex ante probability of there being no other intelligent life in our observable universe, and thus that there should be little surprise when we fail to detect any signs of it,” wrote the team in the research, according to Fox News. “This result dissolves the Fermi paradox, and in doing so removes any need to invoke speculative mechanisms by which civilizations would inevitably fail to have observable effects upon the universe.”

Their research revealed there is a 30 percent chance that humans are alone in the Milky Way galaxy. In addition, the team also found evidence that, should extraterrestrial life exist, it is likely less advanced that what we have on Earth.

”One can answer the Fermi Paradox by saying intelligence is very rare, but then it needs to be tremendously rare,” explained lead author Anders Sandberg, a researcher at Oxford University, according to International Business Times. “Another possibility is that intelligence doesn’t last very long, but it is enough that one civilization survives for it to become visible.”

While this suggests humans are alone, the study is not definitive. Many more processes need to be analyzed before that idea can be fully confirmed in one way or another.

Astronomers find galaxy cluster obscured by quasar

Search is on for more galaxy clusters hidden by very bright, active supermassive black holes.

Astronomers have discovered a large galaxy cluster with a mass of approximately 690 trillion suns that until now was obscured by an extremely bright quasar, an active supermassive black hole feeding on material surrounding it.

Composed of several hundred individual galaxies, the cluster is located about 2.4 billion light years from Earth and surrounds the quasar.

Designated PKS1353-341, the quasar, which is 46 billion times brighter than our Sun, was long thought to be alone in its region of space. It is surrounded by a huge disk of swirling material, of which large chunks are falling into it and in the process radiating high levels of energy as light.

“This might be a short-lived phase that clusters go through, where the central black hole has a quick meal, gets bright, and then fades away again. This could be a blip that we just happened to see. In a million years, this might look like a diffuse fuzzball,” explained Michael McDonald of MIT‘s Kavli Institute for Astrophysics and Space Research.

The discovery of the galaxy cluster suggests other, similar clusters could be hiding behind extremely bright objects. Such clusters provide important information about the amount of matter in the universe and the rate at which the universe is expanding, which is why astronomers are now searching for them.

One reason scientists missed this large cluster is their assumption that clusters appear “fluffy” and give off diffuse X-ray signals, very unlike quasars, which are bright, single-point sources.

“This idea that you could have a rapidly accreting black hole at the center of a cluster–we didn’t think that was something that happened in nature,” McDonald said.

To find more hidden clusters, he and fellow researchers set up a survey titled Clusters Hiding in Plain Sight (CHiPS), which involved looking at archival X-ray images of very bright objects. They then followed up by studying these objects using the Magellan Telescope, an optical observatory in Chile.

If the Magellan observations revealed more galaxies than expected surrounding the bright object, they then observed the point source using the space-based Chandra X-ray Observatory.

“Some 90 percent of these sources turned out not to be clusters,” McDonald said.

The CHiPS survey did find one new galaxy cluster obscured by a very bright supermassive black hole.

Findings of the study have been published in the Astrophysical Journal.

 

Most asteroids come from a few ancient planetesimals

Eighty-five percent of inner main belt asteroids come from five or six ancient objects.

Most asteroids in the belt between Mars and Jupiter as well as meteorites on Earth are the remnants of five or six planetesimals that broke apart in the ancient solar system, according to a new study published in the journal Nature Astronomy.

The asteroid belt is home to about 400,000 asteroids, with those posing the greatest possible threat to Earth located mostly in the inner main belt.

Understanding the origin and evolution of asteroids is important to protecting the Earth from potential impactors, noted study lead author Stanley Dermott of the University of Florida.

“These large bodies whiz by the Earth, so of course we’re very concerned about how many of these there are and what types of materials are in them. If ever one of these comes toward the Earth, and we want to deflect it, we need to know what its nature is.”

In earlier studies, scientists found that many asteroids have very similar compositions and orbits, which they labeled “asteroid families.” Each family likely originated from one larger body broken apart in a long ago impact.

Prior to this study, scientists believed just 44 percent of inner main belt asteroids to belong to five asteroid families.

Dermott and his research team studied asteroids never assigned to any families, specifically focusing on whether their orbits are circular or eccentric along with their tilt or inclination to the Sun’s equator. Their findings indicated 85 percent of inner main belt asteroids come from just five asteroid families. The remaining 15 percent either come from these same families or come from “ghost families,” most of whose asteroids have since been destroyed.

Meteorites on Earth, all of which are somewhat different from one another, also came from the same initial, ancient objects. “We’re saying these meteorites generally come from a small number of objects that were fairly large, hundreds of kilometers in diameter or more,” Dermott added.

Asteroids in the middle and outer main belt likely come from a different, but equally small number of larger parent bodies.

As a next step, Dermott plans to research the process by which asteroids leave the main belt and travel inward to become Near-Earth Objects.

A better understanding of ancient solar system bodies will also help scientists better understand the processes that shaped Earth and provide insight as to where to look for Earth-like exoplanets, he said.

 

Milky Way has merged with numerous galaxies

Studying globular clusters gives scientists insight into galaxy’s history.

Since its formation billions of years ago, the Milky Way has merged with 12 galaxies of similar size and three dwarf galaxies, according to a study by astronomers at the University of Heidelberg in Germany.

The researchers arrived at this conclusion by studying globular clusters, dense clusters comprised of hundreds of thousands of stars, in the Milky Way’s halo.

A galaxy’s halo is spherical region of stars, gas, and dust extending beyond its main structure. It typically contains numerous globular clusters and older, metal-poor stars.

To learn more about the Milky Way’s long history, the research team studied 96 globular clusters orbiting the center of the galaxy, measuring the ages and levels of heavy elements in their stars.

Galaxies with large numbers of stars containing heavy elements are typically older than those with mostly metal-poor stars, as the former have had more time to merge with and devour other galaxies in their neighborhoods.

The Milky Way’s globular clusters were found to contain an abundance of metal-rich stars, indicating the galaxy has been merging with other galaxies for as long as 12 billion years.

In addition to having collided and merged with many galaxies of roughly its size, the Milky Way has also devoured at least two dwarf galaxies, the research team concluded, based on their discovery of 25 globular clusters containing metal-poor stars.

Currently, the galaxy is in the process of merging with the Sagittarius dwarf galaxy, one of nine satellite galaxies in orbit around the Milky Way. Completion of the merger will occur over approximately 100 million years, during which the Milky Way’s powerful gravitational pull will tear the much smaller Sagittarius dwarf galaxy apart.

Suspected to harbor some dark matter, the Sagittarius dwarf galaxy survived several previous collisions with our galaxy, the researchers found.

Remnants of galaxies devoured by the Milky Way exist in the form of stellar streams, which the researchers observed with the 570-megapixel Dark Energy Camera at the Cerro Tololo Inter-American Observatory in Chile.

Based on these stellar streams’ positions and trajectories, the researchers were able to determine they originated in other galaxies that merged with the Milky Way.

A paper on these findings has been accepted for publication in the journal Monthly Notices of the Royal Astronomical Society.

Future humans could overcome expansion of the universe

Dyson spheres could be used to anchor stars within the Milky Way.

Existential threats to humanity range from urgent, to a distant possibility. One such remote threat is the accelerating expansion of the universe. While most wouldn’t consider this a real threat, particle physicist, Dan Hooper, at the Fermi National Accelerator Laboratory, points out why it is a threat we should consider.

He points out that things beyond the cosmic horizon—the maximum distance that light can travel to us within the age of the universe—are beyond our ability to study, or influence. Stars, galaxies, even civilizations are beyond the cosmic horizon, and beyond our ability to contact or see them. According to an article in MIT Technology Review discussing Hooper’s theory, the cosmic horizon is changing and this will affect our neighborhood in the universe, which astronomers call the Local Group. The Local Group (50 nearby galaxies bound to the Milky Way) will be humanity’s home for the foreseeable future. But these galaxies may not always be within our reach to possibly colonize, as the accelerating expansion of the universe sends galaxies over the horizon at a rate that’s increasing.

As Hooper explains, “over the next approximately 100 billion years, all stars residing beyond the Local Group will fall beyond the cosmic horizon and become not only unobservable, but entirely inaccessible.” This eventuality would interfere with humanity’s ability to exploit ever more stars for energy. However, Hooper believes there is a way to mitigate the effects of an expansion. He believes that an advanced civilization could build a Dyson sphere that emits waste radiation in a specific direction to accelerate the sphere—and the star it contains—in the opposite direction of the acceleration. Over time, this technology could be used to gather stars as a source of energy, keeping them inside the cosmic horizon. So, potential problem solved? Well, as the article acknowledges, first the assumption that the expansion of the universe is accelerating would have to be correct.

Up to 35 percent of exoplanets may be ocean worlds

Temperatures and pressures of these worlds may not be conducive to harboring life.

Somewhere between 30 and 35 percent of all exoplanets may be ocean worlds two to four times the size of Earth, according to a team of scientists who presented their findings at the 2018 Goldschmidt Conference of the Geochemical Society.

The researchers analyzed data returned by NASA’s Kepler Space Telescope and Gaia mission and determined that many super-Earths, planets several times larger than our own, likely have compositions that are up to 50 percent water. In contrast, Earth’s composition is just 0.02 percent water.

Two types of super-Earths were identified in the study. Those with 1.5 times Earth’s radius or less are likely to be rocky while those with 2.5 times Earth’s radius are likely to be icy like Uranus and Neptune in our solar system.

Large super-Earths likely have water vapor atmospheres and surface oceans with extreme pressures, whose temperatures may range between 390 and 930 degrees Fahrenheit (200 and 500 degrees Celsius). Structurally, they may resemble gas giants, with cores far beneath their dense atmospheres.

In spite of having high amounts of water, the latter group of planets are not likely to be habitable.

“It was a huge surprise to realize that there must be so many water worlds, said Li Zeng of Harvard University, who led the study.

“This is water, but not as commonly found here on Earth. Their surface temperature is expected to be in the 200 to 500 degree Celsius range. Their surface may be shrouded in a water-vapor-dominated atmosphere, with a liquid water layer underneath. Moving deeper, one would expect to find this water transforms into high-pressure ices before reaching the solid, rocky core,” Zeng said.

He acknowledged that life could develop in layers close to these planets’ surfaces if their pressures, temperatures, and chemical conditions are just right.

The larger water worlds likely formed in processes similar to those that formed the cores of Uranus and Neptune, Zeng added.

NASA’s Transiting Exoplanet Survey Satellite (TESS), which launched earlier this year, and the James Webb Space Telescope (JWST), now scheduled for launch in 2021, will likely find many more water worlds, he noted. Discoveries by space observatories will be followed by ground-based spectroscopic observations.

JWST will enable scientists to identify the components in exoplanets’ atmospheres.

Jets of water vapor found streaming from newborn star

Various complex organic molecules also seen in star-forming region.

Astronomers who observed a turbulent star-forming region using the Atacama Large Millimeter/submillimeter Array’s (ALMA) highest frequency capabilities detected jets of water vapor streaming from a massive newborn star approximately 4,300 light years away.

ALMA uses an array of very precise antennas to study high-frequency radio light waves and was recently equipped with shortwave capabilities, enabling it to see a region in the electromagnetic spectrum at the boundary between infrared and radio wavelengths.

Located in the direction of the constellation Scorpius, the region observed, a section of the Cat’s Paw Nebula or NGC 63341, is an active stellar nursery. Previous ALMA observations of it at lower frequencies revealed it to be an active environment that harbors complex organic molecules.

On April 5, 2018, a team of scientists used ALMA to observe this region with the new, high-frequency technology. The Chilean observatory does this by assigning a series of “bands” designated one through 10, each of which studies a very small part of the spectrum. Band 10, the highest frequency, was used to look at the nebula’s star-forming region.

Two major discoveries were made from these observations–water vapor streaming away from a newborn star in jets and the fingerprints of a variety of molecules.

“High-frequency radio observations like these are normally not possible from the ground. They require the extreme precision and sensitivity of ALMA, along with some of the driest and most stable atmospheric conditions that can be found on Earth,” explained Brett McGuire of the National Radio Astronomy Observatory (NRAO) in Charlottesville, Virginia.

ALMA detected the submillimeter wavelengths that are the fingerprints of light emitted by heavy water, a form of water in which some or all of the hydrogen molecules are replaced by the hydrogen isotope deuterium.

“Normally, we wouldn’t be able to directly see this particular signal at all from the ground. Earth’s atmosphere, even at remarkably arid places, still contains enough water vapor to completely overwhelm this signal from any cosmic source. During exceptionally pristine conditions in the high Atacama Desert, however, ALMA can in fact detect that signal. This is something no other telescope on Earth can achieve,” said Crystal Brogan, also of NRAO.

Most of the material in the protoplanetary disks surrounding baby stars falls onto them. However, a small amount of this material, including heavy water, gas, and other  molecules, is instead directed away from these stars in the form of jets traveling in opposite outward directions.

A paper on the findings has been published in Astrophysical Journal Letters.

Aliens may not be travelling through space – new study reveals limitations of life on ‘super-Earths’

Extraterrestrials on super-Earths may be caged by their planets’ strong gravitational pulls.

A new study places limitations on aliens living on “super-Earths” being able to engage in interstellar travel. “Super-Earth” planets can reach sizes ten times the mass of our own. Their greater mass results in stronger gravitational pulls, making it exceedingly difficult for extraterrestrials to ascend into space, writes Charles Q Choi for Space.com.

Michael Hippke, an independent researcher with the Sonneberg Observatory in Germany researched the difficulty of spaceflight for inhabitants of super-Earths, or exoplanets. According to the study, to launch the equivalent of an Apollo mission, a rocket on a super-Earth would need to have a mass of about 444,000 tons, due to fuel requirements—think of the mass of the Great Pyramid of Giza in Egypt. “On more massive planets, spaceflight would be exponentially more expensive,” Hippke explains.

Scientists previously hypothesized that worlds other than Earth-like ones could offer circumstances suitable for life, possibly being even more habitable because their stronger gravitational pulls would hold thicker atmospheres, better shielding life from harmful cosmic rays. However, Hippke limits this “super-habitability” theory, calculating that the strong gravitational pull of such planets could make it more difficult for extraterrestrials to leave their home.

Hippke calculated the rocket sizes needed to escape a super-Earth 70 percent wider than our planet and 10 times more massive. On such a world, the escape velocity is about 2.4 times greater than on Earth. “Civilizations from super-Earths are much less likely to explore the stars,” Hippke concludes. He believes they would make more “use of lasers or radio telescopes for interstellar communication…” He submitted his findings to the International Journal of Astrobiology.

Mercury likely has dense, thin crust, study reports

A new study shows that Mercury’s crust is roughly 25 percent thinner than previously believed.

Astronomers working at the University of Arizona’s Lunar and Planetary Lab have found new evidence that suggests Mercury’s crust is not as thick as previously thought, according to new research set to be published in the journal Planetary Science Letters.

To make this discovery, the team analyzed data from NASA’s Mercury Surface, Space Environment, Geochemistry and Ranging (MESSENGER) craft. That then enabled them to mathematically calculate the width of Mercury’s crust. Such calculations revealed that the rock is likely both thinner and more dense than previously thought.

Initially, scientists believed that Mercury’s crust measured 22 miles deep. However, the recent research shows that the crust is 16 miles thick. It is likely denser than aluminum as well.

“We know what minerals usually form rocks, and we know what elements each of these minerals contain,” said lead author Michael Sori, a researcher at the University of Arizona, in a statement. “We can intelligently divide all the chemical abundances into a list of minerals. We know the densities of each of these minerals. We add them all up, and we get a map of density.”

This finding is important because it gives credence to the theory that Mercury’s crust came about through volcanic activity. Even so, that does not explain how Mercury’s core — which measures 60 percent of the planet’s volume — is bigger than both the mantle and crust.

While the jury is still out on that, the team behind the research believes that Mercury’s thinness may be the result of massive impacts that stripped away many of its rock formations. There is also a chance solar winds may have taken away parts of the crust and left the planet with a larger core.

Either way, now that scientists are aware of the planet’s crust, they can get a better idea as to how it evolved or shifted over time. Many organizations around the world plan to follow up on the findings by taking a closer look into the distant planet.

For example, the European Space Agency’s BepiColombo mission — which will launch later this year — is set to land on the world in 2025.

“It’s been a long and occasionally bumpy road to this point, and there is still plenty to do until we are ready for launch,” said Ulrich Reininghaus, the BepiColombo project manager who was not involved in the research, according to Tech Times. “But we are extremely pleased to finally move our preparations to the launch site, and are grateful to everyone who has made this possible.”