Monday, May 2, 2016

Supermassive Black Holes In Distant Galaxies Are Mysteriously Aligned

Supermassive Black Holes In Distant Galaxies Are Mysteriously Aligned:



A supermassive black hole has been found in an unusual spot: an isolated region of space where only small, dim galaxies reside. Image credit: NASA/JPL-Caltech


In 1974, astronomers detected a massive source of radio wave emissions coming from the center of our galaxy. Within a few decades time, it was concluded that the radio wave source corresponded to a particularly large, spinning black hole. Known as Sagittarius A, this particular black hole is so large that only the designation "supermassive" would do. Since its discovery, astronomers have come to conclude that supermassive black holes (SMBHs) lie at the center of almost all of the known massive galaxies.But thanks to a recent radio imaging by a team of researchers from the University of Cape Town and University of the Western Cape, in South Africa, it has been further determined that in a region of the distant universe, the SMBHs are all spinning out radio jets in the same direction. This finding, which shows an alignment of the jets of galaxies over a large volume of space, is the first of its kind, and could tell us much about the early Universe.This research, which appeared recently in the Monthly Notices of the Royal Astronomical Society, was made possible thanks to a three-year deep radio imaging survey conducted by the Giant Metrewave Radio Telescope (GMRT) in India. After examining the radio waves coming from a region of space called ELAIS-N1, the South African research team found that the jets being produced by these galaxies were all in alignment.This finding could only be explained by venturing that the SMBHs creating them were all spinning in the same direction, which in turn reveals something rather interesting about how these black holes came to be. In essence, the only likely reason why multiple SMBHs could be spinning in the same direction over a large volume of space is if they were the result of primordial mass fluctuations in the early universe.

As Prof. Andrew Russ Taylor - the joint UWC/UCT SKA Chair, Director of the recently-launched Inter-University Institute for Data Intensive Astronomy, and principal author of the Monthly Notices study - explained: "Since these black holes don’t know about each other, or have any way of exchanging information or influencing each other directly over such vast scales, this spin alignment must have occurred during the formation of the galaxies in the early universe."

This was rather surprising, and something the research team wasn't prepared for. Initially, the goal of the project was to explore the faintest radio sources in the universe using the latest generation of radio telescopes; which, it was hoped, would provide a preview of what the next-generation of telescopes like South Africa's MeerKAT telescope and the Square Kilometre Array (SKA) will provide once they go online. While previous studies have shown that there are deviations in the orientations of certain galaxies, this was the first time that astronomers were able to use the jets produced by the SMBA holes to reveal their alignments. After noting the symmetry that was apparent between them, the research team considered several options as to why an alignment in galaxies (even on scales larger than galaxy clusters) might be.However, it is important to note that a large-scale spin distribution of this kind has never been predicted by theories. Such an unknown phenomenon certainly presents a challenge when it comes to prevailing theories about the origins of the Universe, which will have to be revised somewhat to account for this. While earlier studies have detected deviations from uniformity in the orientations of galaxies, this was the first time that radio jets were used to measure their alignment. This was made possible thanks to the sensitivity of the radio images used, which also benefitted from the fact that measurements of the intensity of radio emissions are not effected by things like scattering, extinction and Faraday Rotation (which may have effected other studies).

Furthermore, the presence of alignments of this nature could shed light on the orientation and evolution of these galaxies, particularly in relation to large-scale structures. They could also help astronomer to learn more about the motions in the primordial matter fluctuations that gave rise to the current structure of the Universe. As Taylor and the other authors of the paper also note, it will be interesting to compare this with predictions of angular momentum structure from universe simulations.

In recent years, several simulations have been produced to model the large-sale structure of the Universe and how it evolved. These include, but are not limited to, the FastSound project - which has been surveying galaxies in the Universe using the Subaru Telescope’s Fiber Multi-Object Spectrograph (FMOS) - and the DESI Project, which will rely on the Mayall Telescope at the Kitt Peak National Observatory in Arizona to chart the history of the Universe going back 11 billion years and create an extremely precise 3D map.

And then there's the Australian Square-Kilometer Array Pathfinder (ASKAP), a radio telescope currently being commissioned by the Commonwealth Scientific and Industrial Research Organization (CSIRO) at the Murchison Radio-astronomy Observatory (MRO) in Western Australia. When completed, the ASKAP array will combine fast survey speed and high sensitivity to study the early Universe.

In the coming years, these projects, combined with this new information about the alignments of supermassive black holes, are likely to shed some serious light on how the Universe came to be, from creation to the present day. As Taylor puts it, "We’re beginning to understand how the large-scale structure of the universe came about, starting from the Big Bang and growing as a result of disturbances in the early universe, to what we have today, and that helps us explore what the universe of tomorrow will be like."

Further Reading: Royal Astronomical Society

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Posted by Nelio Inacio at 3:28 PM 0 comments

An Earth-like Planet Only 16 Light Years Away?

An Earth-like Planet Only 16 Light Years Away?:



An artistic representation of Gliese 832 c against a stellar nebula background. A new paper says Gliese 832 might be home to another planet similar to this, but in the habitable zone. Credit: Planetary Habitability Laboratory at the University of Puerto Rico, Arecibo, NASA/Hubble, Stellarium.


Earth may have a new neighbour, in the form of an Earth-like planet in a solar system only 16 light years away. The planet orbits a star named Gliese 832, and that solar system already hosts two other known exoplanets: Gliese 832B and Gliese 832C. The findings were reported in a new paper by Suman Satyal at the University of Texas, and colleagues J. Gri?th, and Z. E. Musielak.Gliese 832B is a gas giant similar to Jupiter, at 0.64 the mass of Jupiter, and it orbits its star at 3.5 AU. G832B probably plays a role similar to Jupiter in our Solar System, by setting gravitational equilibrium. Gliese 832C is a Super-Earth about 5 times as massive as Earth, and it orbits the star at a very close 0.16 AU. G832C is a rocky planet on the inner edge of the habitable zone, but is likely too close to its star for habitability. Gliese 832, the star at the center of it all, is a red dwarf about half the size of our Sun, in both mass and radius.The newly discovered planet is still hypothetical at this point, and the researchers put its mass at between 1 and 15 Earth masses, and its orbit at between 0.25 to 2.0 AU from Gliese 582, its host star.The two previously discovered planets in Gliese 832 were discovered using the radial velocity technique. Radial velocity detects planets by looking for wobbles in the host star, as it responds to the gravitational tug exerted on it by planets in orbit. These wobbles are observable through the Doppler effect, as the light of the affected star is red-shifted and blue-shifted as it moves.[embed]https://www.youtube.com/watch?v=t2xTlv_I6ac[/embed]The team behind this study re-analyzed the data from the Gliese 832 system, based on the idea that the vast distance between the two already-detected planets would be home to another planet. According to other solar systems studied by Kepler, it would be highly unusual for such a gap to exist.As they say in their paper, the main thrust of the study is to explore the gravitational effect that the large outer planet has on the smaller inner planet, and also on the hypothetical Super-Earth that may inhabit the system. The team conducted numerical simulations and created models constrained by what's known about the Gliese 832 system to conclude that an Earth-like planet may orbit Gliese 832.This can all sound like some hocus-pocus in a way, as my non-science-minded friends like to point out. Just punch in some numbers until it shows an Earth-like planet, then publish and get attention. But it's not. This kind of modelling and simulation is very rigorous.Putting in all the data that's known about the Gliese 832 system, including radial velocity data, orbital inclinations, and gravitational relationships between the planets and the star, and between the planets themselves, yields bands of probability where previously undetected planets might exist. This result tells planet hunters where to start looking for planets.In the case of this paper, the result indicates that "there is a slim window of about 0.03 AU where an Earth-like planet could be stable as well as remain in the HZ." The authors are quick to point out that the existence of this planet is not proven, only possible.[embed]https://www.youtube.com/watch?v=y6g7c00v_nY[/embed]The other planets were found using the radial velocity method, which is pretty reliable. But radial velocity only provides clues to the existence of planets, it doesn't prove that they're there. Yet. The authors acknowledge that a larger number of radial velocity observations are needed to confirm the existence of this new planet. Barring that, either the transit method employed by the Kepler spacecraft, or direct observation with powerful telescopes, may also provide positive proof.So far, the Kepler spacecraft has confirmed the existence of 1,041 planets. But Kepler can't look everywhere for planets. Studies like these are crucial in giving Kepler starting points in its search for exoplanets. If an exoplanet can be confirmed in the Gliese 832 system, then it also confirms the accuracy of the simulation that the team behind this paper performed.If confirmed, G832 C would join a growing list of exoplanets. It wasn't long ago that we knew almost nothing about other solar systems. We only had knowledge of our own. And even though it was always unlikely that our Solar System would for some reason be special, we had no certain knowledge of the population of exoplanets in other solar systems.Studies like this one point to our growing understanding of the dynamics of other solar systems, and the population of exoplanets in the Milky Way, and most likely throughout the cosmos.

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Posted by Nelio Inacio at 3:28 PM 0 comments

Landslides and Bright Craters on Ceres Revealed in Marvelous New Images from Dawn

Landslides and Bright Craters on Ceres Revealed in Marvelous New Images from Dawn:



Ceres' Haulani Crater, with a diameter of 21 miles (34 kilometers), shows evidence of landslides from its crater rim. Credits: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA


Now in orbit for just over a year at dwarf planet Ceres, NASA’s Dawn spacecraft continues to astound us with new discoveries gleaned from spectral and imagery data captured at ever decreasing orbits as well as since the probe arrived last December at the lowest altitude it will ever reach during the mission.Mission scientists have just released marvelous new images of Haulani and Oxo craters revealing landslides and mysterious slumps at several of the mysterious bright craters on Ceres - the largest asteroid in the main Asteroid Belt between Mars and Jupiter.The newly released image of oddly shaped Haulani crater above, shows the crater in enhanced color and reveals evidence of landslides emanating from its crater rim.“Rays of bluish ejected material are prominent in this image. The color blue in such views has been associated with young features on Ceres,” according to the Dawn science team.“Enhanced color allows scientists to gain insight into materials and how they relate to surface morphology.” Look at the image closely and you’ll see its actually polygonal in nature - meaning it resembles a shape made of straight lines - unlike most craters in our solar system which are nearly circular.”The straight edges of some Cerean craters, including Haulani, result from pre-existing stress patterns and faults beneath the surface,” says the science team.Haulani Crater has a diameter of 21 miles (34 kilometers) and apparently was formed by an impacting object relatively recently in geologic time and is also one of the brightest areas on Ceres.“Haulani perfectly displays the properties we would expect from a fresh impact into the surface of Ceres. The crater floor is largely free of impacts, and it contrasts sharply in color from older parts of the surface," said Martin Hoffmann, co-investigator on the Dawn framing camera team, based at the Max Planck Institute for Solar System Research, Göttingen, Germany, in a statement.The enhanced color image was created from data gathered at Dawn’s High Altitude Mapping Orbit (HAMO), while orbiting at an altitude of 915 miles (1,470 kilometers) from Ceres.Data from Dawn’s VIR instrument shows that Haulani’s surface is comprised of different materials than its surroundings."False-color images of Haulani show that material excavated by an impact is different than the general surface composition of Ceres. The diversity of materials implies either that there is a mixed layer underneath, or that the impact itself changed the properties of the materials," said Maria Cristina de Sanctis, the VIR instrument lead scientist, based at the National Institute of Astrophysics, Rome.Since mid-December, Dawn has been orbiting Ceres in its Low Altitude Mapping Orbit (LAMO), at a distance of 240 miles (385 kilometers) from Ceres, resulting in the most stunning images ever of the dwarf planet.By way of comparison the much higher resolution image of Haulani crater below, is a mosaic of views assembled from multiple images taken from LAMO at less than a third of the HAMO image distance - at only 240 miles (385 kilometers) above Ceres.Dawn has also been busy imaging Oxo Crater, which despite its small size of merely 6-mile-wide (10-kilometer-wide) actually counts as a “hidden treasure” on Ceres - because it’s the second-brightest feature on Ceres!Only the mysterious bright region comprising a multitude of spots inside Occator Crater shine more brightly on Ceres.Most importantly, Oxo Crater is the only place on Ceres where Dawn has detected water at the surface so far. Via VIR, Dawn data indicate that the water exists either in the form of ice or hydrated minerals. Scientists speculate that the water was exposed either during a landslide or an impact."Little Oxo may be poised to make a big contribution to understanding the upper crust of Ceres," said Chris Russell, principal investigator of the mission, based at the University of California, Los Angeles.The signatures of minerals detected on the floor of Oxo crater appears to be different from the rest of Ceres.Furthermore Oxo is “also unique because of the relatively large "slump" in its crater rim, where a mass of material has dropped below the surface.”Dawn is Earth’s first probe in human history to explore any dwarf planet, the first to explore Ceres up close and the first to orbit two celestial bodies.The asteroid Vesta was Dawn’s first orbital target where it conducted extensive observations of the bizarre world for over a year in 2011 and 2012.The mission is expected to last until at least later into 2016, and possibly longer, depending upon fuel reserves.Dawn will remain at its current altitude at LAMO for the rest of its mission, and indefinitely afterward, even when no further communications are possible.Stay tuned here for Ken's continuing Earth and planetary science and human spaceflight news.Ken Kremer

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Posted by Nelio Inacio at 3:27 PM 0 comments

How Do We Know There’s a Planet 9?

How Do We Know There’s a Planet 9?:

At this point, I think the astronomy textbook publishers should just give up. They’d like to tell you how many planets there are in the Solar System, they really would. But astronomers just can’t stop discovering new worlds, and messing up the numbers.

Things were simple when there were only 6 planets. The 5 visible with the unaided eye, and the Earth, of course. Then Uranus was discovered in 1781 by William Herschel, which made it 7. Then a bunch of asteroids, like Ceres, Vesta and Pallas pushed the number into the teens until astronomers realized these were probably a whole new class of objects. Back to 7.

Then Neptune in 1846 by Urbain Le Verrier and Johann Galle, which makes 8. Then Pluto in 1930 and we have our familiar 9.

But astronomy marches onward. Eris was discovered in 2005, which caused astronomers to create a whole new classification of dwarf planet, and ultimately downgrading Pluto. Back to 8.

It seriously looked like 8 was going to be the final number, and the textbook writers could return to their computers for one last update.

A predicted consequence of Planet Nine is that a second set of confined objects should also exist. These objects are forced into positions at right angles to Planet Nine and into orbits that are perpendicular to the plane of the solar system. Five known objects (blue) fit this prediction precisely. Credit: Caltech/R. Hurt (IPAC) [Diagram was created using WorldWide Telescope.]
A predicted consequence of Planet Nine is that a second set of confined objects should also exist. These objects are forced into positions at right angles to Planet Nine and into orbits that are perpendicular to the plane of the solar system. Five known objects (blue) fit this prediction precisely.
Credit: Caltech/R. Hurt (IPAC) [Diagram was created using WorldWide Telescope.]
Astronomers, however, had other plans. In 2014, Chad Trujillo and Scott Shepard were studying the motions of large objects in the Kuiper Belt and realized that a large planet in the outer Solar System must be messing with orbits in the region.

This was confirmed and fine tuned by other astronomers, which drew the attention of Mike Brown and Konstantin Batygin. The name Mike Brown might be familiar to you. Perhaps the name, Mike “Pluto Killer” Brown? Mike and his team were the ones who originally discovered Eris, leading to the demotion of Pluto.

Brown and Batygin were looking to find flaws in the research of Trujillo and Shepard, and they painstakingly analyzed the movement of various Kuiper Belt Objects. They found that six different objects all seem to follow a very similar elliptical orbit that points back to the same region in space.

All these worlds are inclined at a plane of about 30-degrees from pretty much everything else in the Solar System. In the words of Mike Brown, the odds of these orbits all occurring like this are about 1 in 100.

Animated diagram showing the spacing of the Solar Systems planet’s, the unusually closely spaced orbits of six of the most distant KBOs, and the possible “Planet 9”. Credit: Caltech/nagualdesign
Animated diagram showing the spacing of the Solar Systems planet’s, the unusually closely spaced orbits of six of the most distant KBOs, and the possible “Planet 9”. Credit: Caltech/nagualdesign
Instead of a random coincidence, Brown and Batygin think there’s a massive planet way out beyond the orbit of Pluto, about 200 times further than the distance from the Sun to the Earth. This planet would be Neptune-sized, roughly 10 times more massive than Earth.

But why haven’t they actually observed it yet? Based on their calculations, this planet should be bright enough to be visible in mid-range observatories, and definitely within the capabilities of the world’s largest telescopes, like Keck, Palomar, Gemini, and Hubble, of course.

The trick is to know precisely where to look. All of these telescopes can resolve incredibly faint objects, as long as they focus in one tiny spot. But which spot. The entire sky has a lot of tiny spots to look at.

Artist's impression of Planet Nine, blocking out the Milky Way. The Sun is in the distance, with the orbit of Neptune shown as a ring. Credit: ESO/Tomruen/nagualdesign
Artist’s impression of Planet Nine, blocking out the Milky Way. The Sun is in the distance, with the orbit of Neptune shown as a ring. Credit: ESO/Tomruen/nagualdesign
Based on the calculations, it appears that Planet 9 is hiding in the plane of the Milky Way, camouflaged by the dense stars of the galaxy. But astronomers will be scanning the skies, and hope a survey will pick it up, anytime now.

But wait a second, does this mean that we’re all going to die? Because I read on the internet and saw some YouTube videos that this is the planet that’s going to crash into the Earth, or flip our poles, or something.

Nope, we’re safe. Like I just said, the best astronomers with the most powerful telescopes in the world and space haven’t been able to turn anything up. While the conspiracy theorists have been threatening up with certain death from Planet X for decades now – supposedly, it’ll arrive any day now.

But it won’t. Assuming it does exist, Planet 9 has been orbiting the Sun for billions of years, way way out beyond the orbit of Pluto. It’s not coming towards us, it’s not throwing objects at us, and it’s definitely not going to usher in the Age of Aquarius.

Once again, we get to watch science in the making. Astronomers are gathering evidence that Planet 9 exists based on its gravitational influence. And if we’re lucky, the actual planet will turn up in the next few years. Then we’ll have 9 planets in the Solar System again.

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Posted by Nelio Inacio at 3:26 PM 0 comments

How Do We Terraform Jupiter’s Moons?

How Do We Terraform Jupiter’s Moons?:



Surface features of the four members at different levels of zoom in each row


Fans of Arthur C. Clarke may recall how in his novel, 2010: Odyssey Two (or the movie adaptation called 2010: The Year We Make Contact), an alien species turned Jupiter into a new star. In so doing, Jupiter's moon Europa was permanently terraformed, as its icy surface melted, an atmosphere formed, and all the life living in the moon's oceans began to emerge and thrive on the surface.As we explained in a previous video ("Could Jupiter Become a Star") turning Jupiter into a star is not exactly doable (not yet, anyway). However, there are several proposals on how we could go about transforming some of Jupiter's moons in order to make them habitable by human beings. In short, it is possible that humans could terraform one of more of the Jovians to make it suitable for full-scale human settlement someday.

The Jovian Moons:

Within the Jupiter system, there are 67 confirmed moons of varying size, shape and composition. In honor of Jupiter's namesake, they are sometimes collectively referred to as the Jovians. Of these, the four largest - Io, Europa, Ganymede and Callisto - are known as the Galileans (in honor of their founder, Galileo Galilei). These four moons are among the largest in the Solar System, with Ganymede being the largest of them all, and even larger than the planet Mercury.In addition, three of these moons - Europa, Ganymede and Callisto - are all believed or known to have interior oceans at or near their core-mantle boundary. The presence of warm water oceans is not only considered an indication of potential life on these moons, but is also cited as a reason for possible human habitation.https://youtu.be/ZErO1MCTj_kOf the Galilean Moons, Io, Europa and Ganymede are all in orbital resonance with each other. Io has a 2:1 mean-motion orbital resonance with Europa and a 4:1 resonance with Ganymede, which means that it completes two orbits of Jupiter for every one orbit of Europa, and four orbits for every orbit Ganymede. This resonance helps maintain these moons' orbital eccentricities, which in turn triggers tidal flexing their interiors.Naturally, each moon presents its own share of advantages and disadvantages when it comes to exploration, settlement, and terraforming. Ultimately, these come down to the particular moon's structure and composition, its proximity to Jupiter, the availability of water, and whether or not the moon in question is dominated by Jupiter's powerful magnetic field.

Possible Methods:

The process of converting Jupiter's Galilean moons is really quite simple. Basically, its all about leveraging the indigenous resources and the moons' own interactions with Jupiter's magnetic field to create a breathable atmosphere. The process would begin by heating the surface in order to sublimate the ice, a process which could involve orbital mirrors to focus sunlight onto the surface, nuclear detonators, or crashing comets/meteors into the surface.Once the surface ice begins to melt, it would form dense clouds of water vapor and gaseous volatiles (such as carbon dioxide, methane and ammonia). These would in turn create a greenhouse effect, warming the surface even more, and triggering a process known as radiolysis (the dissociation of molecules through exposure to nuclear radiation). Basically, the exposure of water vapor to Jupiter's radiation would result in the creation of hydrogen and oxygen gas, the former of which would escape into space while the latter remained closer to the surface. This process already takes place around Europa, Ganymede and Callisto, and is responsible for their tenuous atmospheres (which contain oxygen gas).And since ammonia is predominantly composed of nitrogen, it could be converted into nitrogen gas (N²) through the introduction of certain strains of bacteria. These would include members of the Nitrosomonas, Pseudomonas and Clostridium species, which would convert ammonia gas into nitrites (NO²-), and then nitrites into nitrogen gas. With nitrogen acting as a buffer gas, a nitrogen-oxygen atmosphere with sufficient air pressure to sustain humans could be created.Another option falls under the heading of "paraterraforming" - a process where a world is enclosed (in whole or in part) in an artificial shell in order to transform its environment. In the case of the Jovians, this would involve building large "Shell Worlds" to encase them, keeping the atmospheres inside long enough to effect long-term changes.Within this shell, Europa, Ganymede and Callisto could have their temperatures slowly raised, the water-vapor atmospheres could be exposed to ultra-violet radiation from internal UV lights, bacteria could then be introduced, and other elements added as needed. Such a shell would ensure that the process of creating of an atmosphere could be carefully controlled and none would be lost before the process was complete.

Io:

With a mean radius of 1821.6 ± 0.5 km, and an average distance (semi-major axis) of 421,700 km from Jupiter, Io is the innermost of the Galileans. Because of this, Io is completely enveloped by Jupiter's powerful magnetic field, which also why the surface is exposed to significant amounts of harmful radiation. In fact, Io receives an estimated 3,600 rem (36 Sv) of ionizing radiation per day, whereas living organisms here on Earth experience an average of 24 rem per year! The moon has the shortest orbital period of any of the Galileans, taking roughly 42.5 hours to complete a single orbit around the gas giant. The moon's 2:1 and 4:1 orbital resonance with Europa and Ganymede (see below) also contributes to its orbital eccentricity of 0.0041, which is the primary reason for Io's geologic activity.With a mean density of 3.528 ± 0.006 g/cm3, Io has the highest density of any moon in the Solar System, and is significantly denser than the other Galilean Moons. Composed primarily of silicate rock and iron, it is closer in bulk composition to the terrestrial planets than to other satellites in the outer Solar System, which are mostly composed of a mix of water ice and silicates.Unlike its Jovian cousins, Io has no warm-water ocean beneath its surface. In fact, based on magnetic measurements and heat-flow observations, a magma ocean is believed to exist some 50 km below the surface, which itself is about 50 km thick and makes up 10% of the mantle.  It is estimated that the temperature in the magma ocean reaches 1473 K (1200 °C/2192 °F).The main source of internal heat that allows for this comes from tidal flexing, which is the result of Io’s orbital resonance with Europa and Ganymede. The friction or dissipation produced in Io’s interior due to this varying tidal pull creates significant tidal heating within Io’s interior, melting a significant amount of Io’s mantle and core.https://youtu.be/08X9tET-d2kThis heat is also responsible for Io’s volcanic activity and its observed heat flow, and periodically causes lava to erupt up to 500 km (300 mi) into space. Consistently, the surface of is covered in smooth plains dotted with tall mountains, pits of various shapes and sizes, and volcanic lava flows. It’s colorful appearance (a combination of orange, yellow, green, white/grey, etc.) is also indicative of volcanic activity which has covered the surface in sulfuric and silicate compounds and leads to surface renewal.Io contains little to no water, though small pockets of water ice or hydrated minerals have been tentatively identified, most notably on the northwest flank of the mountain Gish Bar Mons. In fact, Io has the least amount of water of any known body in the Solar System, which is likely due to Jupiter being hot enough early in the evolution of the Solar System to drive volatile materials like water off its surface.Taken together, all of this adds up to Io being a total non-starter when it comes to terraforming or settlement. The planet is far too hostile, far too dry, and far too volcanically active to ever be turned into something habitable!

Europa:

Europa, by contrast, has a lot of appeal for proponents of terraforming. If Io could be characterized as hellish, lava-spewing place (and it certainly can!), then Europa would be calm, icy and watery by comparison. With a mean radius of about 1560 km and a mass of 4.7998 ×1022 kg, Europa is also slightly smaller than Earth’s Moon, which makes it the sixth-largest moon and fifteenth largest object in the Solar System.https://youtu.be/m25i1edwiKsIt’s orbit is nearly circular, with a eccentricity of 0.09, and lies at an average distance of 670 900 km from Jupiter. The moon takes 3.55 Earth days to complete a single orbit around Jupiter, and is tidally locked with the planet (though some theories say that this may not be absolute). At this distance from Jupiter, Europa still experiences quite a bit of radiation, averaging about 540 rem per day. Europa is significantly more dense than the other Galilean Moons (except for Io), which indicates that its interior is differentiated between a rock interior composed of silicate rock and a possible iron core. Above this rocky interior is layer of water ice that is estimated to be around 100 km (62 mi) thick, likely differentiated between a frozen upper crust and  a liquid water ocean beneath.If present, this ocean is likely a warm-water, salty ocean that contains organic molecules, is oxygenated, and heated by Europa’s geologically-active core. Given the combination of these factors, it is considered a strong possibility that organic life also exists in this ocean, possibly in microbial or even multi-celled form, most likely in environments similar to Earth’s deep-ocean hydrothermal vents.Because of its abundant water, which comes in both liquid and solid form, Europa is a popular candidate for proponents of colonization and terraforming. Using nuclear devices, cometary impacts, or some other means to increase the surface temperature, Europa's surface ice could be sublimated and form a massive atmosphere of water vapor.https://youtu.be/GqTaDCt_F1YThis vapor would then undergo radiolysis due to exposure to Jupiter’s magnetic field, converting it into oxygen gas (which would stay close to the planet) and hydrogen that would escape into space. The resulting planet would be an ocean world, where floating settlements could be built that floated across the surface (due to oceans depths of ~100 km, they could not be anchored). Because Europa is tidally-locked, these colonies could move from the day-side to the night-side in order to create the illusion of a diurnal cycle.

Ganymede:

Ganymede’s is the third most distant moon from Jupiter, and orbits at an average distance (semi-major axis) of 1,070,400 km – varying from 1,069,200 km at periapsis to at 1,071,600 km apoapsis. At this distance, it takes seven days and three hours to completes a single revolution. Like most known moons, Ganymede is tidally locked, with one side always facing toward the planet.With a mean radius of 2634.1 ± 0.3 kilometers (the equivalent of 0.413 Earths), Ganymede is the largest moon in the Solar System, even larger than the planet Mercury. However, with a mass of 1.4819 x 10²³ kg (the equivalent of 0.025 Earths), it is only half as massive, which is due to its composition, which consists of water ice and silicate rock.Ganymede is considered another possible candidate for human settlement - and even terraforming - for several reasons. For one, as Jupiter's largest moon, Ganymede has a gravitational force of 1.428 m/s2 (the equivalent of 0.146 g) which is comparable to Earth's Moon. Sufficient enough to limit the effects of muscle and bone degeneration, this lower gravity also means that the moon has a lower escape velocity - which means it would take considerably less fuel for rockets to take off from the surface.What's more, the presence of a magnetosphere means that colonists would be better shielded from cosmic radiation than on other bodies, and more shielded from Jupiter's radiation than Europa or Io. All told, Ganymede receives about 8 rem of radiation per day - a significant reduction from Europa and Io, but still well above human tolerances. The prevalence of water ice means that colonists could also produce breathable oxygen, their own drinking water, and would be able to synthesize rocket fuel. Like Europa, this could be done by heating up the surface through various means, sublimating the water ice, and allowing radiolysis to convert it into oxygen. Again, the result would be an ocean world, but one with significantly deeper oceans (~800 km).And then there is the distinct possibility that Ganymede, like Europa, has an interior ocean due to the heat created by tidal flexing in its mantle. This heat could be transferred into the water via hydrothermal vents, which could provide the necessary heat and energy to sustain life. Combined with oxygenated water, life forms could exist at the core-mantle boundary in the form of extremophiles, much like on Europa.

Callisto:

Callisto is the outermost of the Galileans, orbiting Jupiter at an average distance (semi-major axis) of 1,882,700 km. With a mean radius of 2410.3 ± 1.5 km (0.378 Earths) and a mass of 1.0759 × 1023 kg (0.018 Earths), Callisto is the second largest of  Jupiter’s moons (after Ganymede) and the third largest satellite in the solar system. It is similarly comparable in size to Mercury – being 99% as large – but due to its mixed composition, it has less than one-third of Mercury mass.Compared to the other Galileans, Callisto presents numerous advantages as far as colonization is concerned. Much like the others, the moon has an abundant supply of water in the form of surface ice (but also possibly liquid water beneath the surface). But unlike the others, Callisto's distance from Jupiter means that colonists would have far less to worry about in terms of radiation. In fact, with a surface exposure of about  0.01 rem a day, Callisto is well within human tolerances.Much like Europa and Ganymede, and Saturn’s moons of Enceladus, Mimas, Dione, Titan, the possible existence of a subsurface ocean on Callisto has led many scientists to speculate about the possibility of life. This is particularly likely if the interior ocean is made up of salt-water, since halophiles (which thrive in high salt concentrations) could live there.However, the environmental conditions necessary for life to appear (which include the presence of sufficient heat due to tidal flexing) are more likely on Europa and Ganymede. The main difference is the lack of contact between the rocky material and the interior ocean, as well as the lower heat flux in Callisto’s interior. In essence, while Callisto possesses the necessary pre-biotic chemistry to host life, it lacks the necessary energy.Like Europa and Ganymede, the process of terraforming Callisto would involve heating up the surface in order to sublimate the surface ice and create an atmosphere, one which produces oxygen through radiolysis. The resulting world would be an ocean planet, but with oceans that reached to depths of between 130 and 350 km.https://youtu.be/NGjK_UQbkLI

Potential Challenges:

Okay, we've covered the potential methods and targets, which means its time for the bad news. To break it down, converting one or more of the Galileans into something habitable to humans presents many difficulties, some of which may prove to be insurmountable. These include, but are are not limited to:

  1. Distance
  2. Resources/Infrastructure
  3. Natural Hazards
  4. Sustainability
  5. Ethical Considerations
Basically, the Jovian system is pretty far from Earth. On average, the distance between Jupiter and Earth is 628,411,977 million km (4.2 AU), roughly four times the distance between the Earth and the Sun. To put that into perspective, it took the Voyager probes between 18 months and two years to reach Jupiter from Earth. Ships designed to haul human passengers (with enough supplies and equipment to sustain them) would be much larger and heavier, which would make the travel time even longer.In addition, depending on the method used, transforming the surfaces of Europa, Ganymede, and/or Callisto could require harvesting comets and iceteroids from the edge of the Solar System, which is significantly farther. To put that in perspective, it took the New Horizons mission over eight years to reach Pluto and the Kuiper Belt. And since any mission to this region of space would need to haul back several tons of icy cargo, the wait time involved would be on the order of decades.Ergo, any vessels transporting human crews to the Jovian system would likely have to rely on cryogenics or hibernation-related technology in order to be smaller, faster and more cost-effective. While this sort of technology is being investigated for crewed missions to Mars, it is still very much in the research and development phase.As for transport missions to and from the Kuiper Belt, these ships could be automated, but would have to come equipped with advanced propulsion systems in order to make the trips in a decent amount of time. This could take the form of Nuclear-Thermal Propulsion (NTP), Fusion-drive systems, or some other advanced concept. So far, no such drive systems exist, with some being decades or more away from feasibility.An alternative to this last item could be to harvest asteroids from near Earth, the Asteroid Belt, or Jupiter's Trojans. However, this brings up the second aspect of this challenge, which is the problem of infrastructure. In order to mount multiple crewed missions to the Jovian system, as well as asteroid/iceteroid retrieval missions, a considerable amount of infrastructure would be needed that either does not exist or is severely lacking.This includes having lots of spaceships, which would also need advanced propulsion systems. Just as important is the need for refueling and supply stations between Earth and the Jovian System - like an outpost on the Moon, a permanent base on Mars, and bases on Ceres and in the Asteroid Belt. Harvesting resources from the Kuiper Belt would require more outposts between Jupiter and most likely Pluto.Where "Shell Worlds" are concerned, the challenge remains the same. Building an enveloping structure big enough for an entire moon - which range from 3121.6 km to 5262.4 km in diameter - would require massive amounts of material. While these could be harvested from the nearby Asteroid Belt, it would require thousands of ships and robot workers to mine, haul, and assemble the minerals into large enough shells.Third, radiation would be a significant issue for humans living on Europa or Ganymede. As noted already, Earth organisms are exposed to an average of 24 rem per year, which works out to 0.0657 rem per day. An exposure of approximately 75 rems over a period of a few days is enough to cause radiation poisoning, while about 500 rems over a few days would be fatal. Of all the Galileans, only Callisto falls beneath this terminal limit.As a result, any settlements established on Europa or Ganymede would require radiation shielding, even after the creation of viable atmospheres. This in turn would require large shields to be built in orbit of the moons (requiring another massive investment in resources), or would dictate that all settlements built on the surfaces include heavy radiation shielding.On top of that, as the surfaces of Europa, Ganymede and Callisto (especially Callisto!) will attest, the Jovian system is frequented by space rocks. In fact, most of Jupiter's satellites are asteroids it picked up as they sailed through the system. These satellites are lost on a regular basis, and new ones are added all the time. So colonists would naturally have to worry about space rocks slamming into their ocean world, causing massive waves and blotting out the sky with thick clouds of water vapor.Fourth, the issue of sustainability, has to do with the fact that all of the Jovian moons either do not have a magnetosphere or, in the case of Ganymede, are not powerful enough to block the effects of Jupiter's magnetic field. Because of this, any atmosphere created would be slowly stripped away, much as Mars' atmosphere was slowly stripped away after it lost its magnetosphere about 4.3 billion years ago. In order to maintain the effects of terraforming, colonists would need to replenish the atmosphere over time.Another aspect of sustainability, one which is often overlooked, has to do with the kinds of planets that would result from terraforming. While estimates vary, transforming Europa, Ganymede and Callisto would result in oceans that varied in depth - from 100 km (in the cae of Europa) to extreme depths of up to 800 km (in the case of Ganymede). In contrast, the greatest depth ever measured here on Earth was only about 10 km (6 miles) deep, in the Pacific's Mariana Trench.With oceans this deep, all settlements would have to take the form of floating cities that could not be anchored to solid ground. And in the case of Ganymede, the oceans would account for a considerable portion of the planet. What the physicals effects of this would be are hard to imagine. But it is a safe bet that they would result in tremendously high tides (at best) to water being lost to space.And finally, there is the issue of the ethics of terraforming. If, as scientists currently suspect, there is in fact indigenous life on one or more of the Jovian moons, then the effects of terraforming could have severe consequences or them. For instance, if bacterial life forms exist on the underside of Europa's icy surface, then melting it would mean death for these organisms, since it would remove their only source of protection from radiation.Life forms that exist close to the core-mantle boundary, most likely around hydrothermal vents, would be less effected by the presence of humans on the surface. However, any changes to the ec0logical balance could lead to a chain reaction that would destroy the natural life cycle. And the presence of organisms introduced by humans (i.e. germs), could have a similarly devastating effect.So basically, if we choose to alter the natural environment of one or more of the Jovian moons, we will effectively be risking the annihilation of any indigenous life forms. Such an act would be tantamount to genocide (or xenocide, as the case may be), and exposure to alien organisms would surely pose health risks for human colonists as well.

Conclusions:

All in all, it appears that terraforming the outer Solar System might be a bit of a non-starter. While the prospect of doing it is certainly exciting, and presents many interesting opportunities, the challenges involved do seem to add up. For starters, it doesn't seem likely or practical for us to contemplate doing this until we've established a presence on the Moon, Mars, and in the Asteroid Belt.Second, terraforming any of Jupiter's moons would involve a considerable amount of time, energy and resources. And given that a lot of these moon's resources could be harvested for terraforming other worlds (such as Mars and Venus), would it not make sense to terraform these worlds first and circle back to the outer Solar System later?Third, a terraformed Europa, Ganymede and Callisto would all be water worlds with extremely deep oceans. Would it even be possible to build floating cities on such a world? Or would they be swallowed up by massive tidal waves; or worse, swept off into space by waves so high, they slipped the bonds of the planet's gravity? And how often would the atmosphere need to be replenished in order to ensure it didn't get stripped away?https://youtu.be/kKeenzOsB8UAnd last, but not least, any act of terraforming these moons would invariably threaten any life that already exists there. And the threat caused by exposure wouldn't exactly be one-way. Under all of these circumstances, would it not be better to simply establish outposts on the surface, or perhaps within or directly underneath the ice?

All valid questions, and ones which we will no doubt begin to explore once we start mounting research missions to Europa and the other Jovian moons in the future. And depending on what we find there, we might just choose to put down some roots. And in time, we might even begin thinking about renovating the places so more of our kin can drop by. Before we do any of that, we had better make sure we know what we're doing, and be sure we aren't doing any harm in the process!
We have written many interesting articles about Jupiter's Moons here at Universe Today. Here's What Are Jupiter's Moons?, Io, Jupiter's Volcanic Moon, Jupiter's Moon Europa, Jupiter's Moon Ganymede, and Jupiter's Moon Callisto.To learn more about terraforming, check out The Definitive Guide To Terraforming, How Do We Terraform Mars?, How Do We Terraform Venus?, and How Do We Terraform the Moon? and Could We Terraform Jupiter?For more information, check out NASA's Solar System Exploration page on Jupiter's Moons.

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Stunning Auroras From the Space Station in Ultra HD – Videos

Stunning Auroras From the Space Station in Ultra HD – Videos:



Still image shows a stunning aurora captured from the International Space Station. This frame is from a compilation of ultra-high definition time-lapses of the aurora shot from the space station. Credit: NASA


Stunning high definition views of Earth’s auroras and dancing lights as seen from space like never before have just been released by NASA in the form of ultra-high definition videos (4K) captured from the International Space Station (ISS).Whether seen from the Earth or space, auroras are endlessly fascinating and appreciated by everyone young and old and from all walks of life.The spectacular video compilation, shown below, was created from time-lapses shot from ultra-high definition cameras mounted at several locations on the ISS.It includes HD view of both the Aurora Borealis and Aurora Australis phenomena seen over the northern and southern hemispheres.The video begins with an incredible time lapse sequence of an astronaut cranking open the covers off the domed cupola - everyone’s favorite locale. Along the way it also shows views taken from inside the cupola.The cupola also houses the robotics works station for capturing visiting vehicles like the recently arrived unmanned SpaceX Dragon and Orbital ATK Cygnus cargo freighters carrying science experiments and crew supplies.The video was produced by Harmonic exclusively for NASA TV UHD;https://youtu.be/PBJAR3-UvSQVideo caption: Ultra-high definition (4K) time-lapses of both the Aurora Borealis and Aurora Australis phenomena shot from the International Space Station (ISS). Credit: NASA The video segue ways into multi hued auroral views including Russian Soyuz and Progress capsules, the stations spinning solar panels, truss and robotic arm, flying over Europe, North America, Africa, the Middle East, star fields, the setting sun and moon, and much more.Auroral phenomena occur when electrically charged electrons and protons in the Earth's magnetic field collide with neutral atoms in the upper atmosphere.“The dancing lights of the aurora provide a spectacular show for those on the ground, but also capture the imaginations of scientists who study the aurora and the complex processes that create them,” as described by NASA.Here’s another musical version to enjoy:https://youtu.be/fVMgnmi2D1wThe ISS orbits some 250 miles (400 kilometers) overhead with a multinational crew of six astronauts and cosmonauts living and working aboard.The current Expedition 47 crew is comprised of Jeff Williams and Tim Kopra of NASA, Tim Peake of ESA (European Space Agency) and cosmonauts Yuri Malenchenko, Alexey Ovchinin and Oleg Skripochka of Roscosmos.Some of the imagery was shot by recent prior space station crew members.Here is a recent aurora image taken by flight engineer Tim Peake of ESA as the ISS passed through on Feb. 23, 2016."The @Space_Station just passed straight through a thick green fog of #aurora…eerie but very beautiful,” Peake wrote on social media.A new room was just added to the ISS last weekend when the BEAM experimental expandable habitat was attached to a port on the Tranquility module using the robotic arm.BEAM was carried to the ISS inside the unpressurized trunk section of the recently arrived SpaceX Dragon cargo ship.Stay tuned here for Ken's continuing Earth and planetary science and human spaceflight news.Ken Kremer

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Posted by Nelio Inacio at 3:21 PM 0 comments

NASA Selects Aerojet Rocketdyne to Develop Solar Electric Propulsion for Deep Space Missions

NASA Selects Aerojet Rocketdyne to Develop Solar Electric Propulsion for Deep Space Missions:



This prototype 13-kilowatt Hall thruster was tested at NASA's Glenn Research Center in Cleveland and will be used by industry to develop high-power solar electric propulsion into a flight-qualified system. Credits: NASA


NASA has selected Aerojet Rocketdyne to design and develop an advanced solar electric propulsion (SEP) system that will serve as a critical enabling technology for sending humans and robots on deep space exploration missions to cislunar space, asteroids and the Red Planet.Under the 3 year, $67 million contract award, Aerojet Rocketdyne will develop the engineering development unit for an Advanced Electric Propulsion System (AEPS) with the potential for follow on flight units.NASA hopes that the work will result in a 10 fold increase in “spaceflight transportation fuel efficiency compared to current chemical propulsion technology and more than double thrust capability compared to current electric propulsion systems.”The SEP effort is based in part on NASA’s exploratory work on Hall ion thrusters which trap electrons in a magnetic field and uses them to ionize and accelerate the onboard xenon gas propellant to produce thrust much more efficiently than chemical thrusters.The solar electric propulsion (SEP) system technology will afford benefits both to America’s commercial space and scientific space exploration capabilities.For NASA, the SEP technology can be applied for expeditions to deep space such as NASA’s planned Asteroid Robotic Redirect Mission (ARRM) to snatch a boulder from the surface of an asteroid and return it to cislunar space during the 2020s, as well as to carry out the agency’s ambitious plans to send humans on a ‘Journey to Mars’ during the 2030s.“High power SEP is a perfect example of NASA developing cross cutting technologies to enable both human and robotic deep space missions. Basically it enables high efficiency and better gas mileage,” said Steve Jurczyk, associate administrator of NASA’s Space Technology Mission Directorate (STMD) in Washington, at a media briefing.“The advantage here is the higher power and the higher thrust.”“Our plan right now is to flight test the higher power solar electric propulsion that Aerojet Rocketdyne will develop for us on the Asteroid Redirect Robotic Mission (ARRM), which is going to go out to an asteroid with a robotic system, grab a boulder off of an asteroid, and bring it back to a lunar orbit.”ARRM would launch around 2020 or 2021. Astronauts would blast off several years later in NASA’s Orion crew capsule in 2025 after the robotic probes travels back to lunar orbit.For industry, electric propulsion is used increasingly to maneuver thrusters in Earth orbiting commercial satellites for station keeping in place of fuel.“Through this contract, NASA will be developing advanced electric propulsion elements for initial spaceflight applications, which will pave the way for an advanced solar electric propulsion demonstration mission by the end of the decade,” says Jurczyk.“Development of this technology will advance our future in-space transportation capability for a variety of NASA deep space human and robotic exploration missions, as well as private commercial space missions.”“This is also a critical capability for enabling human missions to Mars, with respect to delivering cargo to the surface to Mars that will allow people to live and work there on the surface. Also for combined chemical and SEP systems on a spacecraft to propel humans to Mars,” elaborated Jurczyk at the briefing.“Another application is round trip robotic science missions to Mars to bring back samples - such as a Mars Sample Return (MSR) mission.”The starting point is NASA’s development and technology readiness testing of a prototype 13-kilowatt Hall thruster and power processing unit at NASA's Glenn Research Center in Cleveland.Under the contract award Aerojet Rocketdyne aims to carry out the industrial development of “high-power solar electric propulsion into a flight-qualified system.”They will develop, build, test and deliver “an integrated electric propulsion system consisting of a thruster, power processing unit (PPU), low-pressure xenon flow controller, and electrical harness,” as an engineering development unit.This engineering development unit serves as the basis for producing commercial flight units.If successful, NASA has an option to purchase up to four integrated flight units for actual space missions. Engineers from NASA Glenn and the Jet Propulsion Laboratory (JPL) will provide technical support.“We could string together four of these engine units to get approximately 50 kilowatts of electrical propulsion capability and with that we can do significant orbital transfer operations. That then becomes the next step in deep space exploration operations that we are trying to do,” said Bryan Smith, director of the Space Flight Systems Directorate at NASA’s Glenn Research Center in Cleveland, at the media briefing.“We hope to buy four of these units for the ARRM mission.”What were some of NASA’s research and development (R&D) activities and further plans for Aerojet Rocketdyne?“NASA is driving out the technology itself for feasibility. So we produced a developmental device to operate at these levels,” Smith told Universe Today during the briefing.“Other key characteristics we were looking for is the ability to do magnetic shielding. The purpose was to allow for a long life thruster operation. We investigated attributes like thermal problems and balancing the erosion mechanisms in developmental units. So we were looking for things to get longer life and feasibility in developmental units.”“Once we were comfortable with the feasibility in developmental units, we are now transferring the information, technology and knowhow into what is a production article, in this contract.”Solar electric ion propulsion is already being used in NASA’s hugely successful Dawn asteroid orbiter mission.Dawn was launched in 2007. It orbited and surveyed Vesta in 2011 and 2012 and then traveled outward to Ceres.Dawn arrived at dwarf planet Ceres in March 2015 and is currently conducting breakthrough science at its lowest planned science mapping orbit.A key part of the Journey to Mars, NASA will be sending cargo missions to the Red Planet to pave the way for human expeditions with the Orion crew module and Space Launch System.Aerojet Rocketdyne states that “Solar Electric Propulsion (SEP) systems have demonstrated the ability to reduce the mission cost for NASA Human Exploration cargo missions by more than 50 percent through the use of existing flight-proven SEP systems.”“Using a SEP tug for cargo delivery, combined with NASA’s Space Launch System and the Orion crew module, provides an affordable path for deep space exploration,” said Aerojet Rocketdyne Vice President, Space and Launch Systems, Julie Van Kleeck.Another near term application of high power solar electric propulsion could be for NASA’s proposed Mars 2022 telecom orbiter, said Smith at the media briefing.Other NASA technology work in progress includes development of more efficient, advanced solar array systems to generate the additional power required for the larger electric thrusters.Orbital ATK was part of the development effort and already used some of its technology development in the ultraflex solar arrays on the recent Cygnus cargo ships delivering supplies to the ISS. Stay tuned here for Ken's continuing Earth and planetary science and human spaceflight news.Ken Kremer

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Posted by Nelio Inacio at 3:20 PM 0 comments

Bayesian Analysis Rains On Exoplanet Life Parade

Bayesian Analysis Rains On Exoplanet Life Parade:



An exoplanet seen from its moon (artist's impression). Via the IAU.


Is there life on other planets, somewhere in this enormous Universe? That's probably the most compelling question we can ask. A lot of space science and space missions are pointed directly at that question.The Kepler mission is designed to find exoplanets, which are planets orbiting other stars. More specifically, its aim is to find planets situated in the habitable zone around their star. And it's done so. The Kepler mission has found 297 confirmed and candidate planets that are likely in the habitable zone of their star, and it's only looked at a tiny patch of the sky.But we don't know if any of them harbour life, or if Mars ever did, or if anywhere ever did. We just don't know. But since the question of life elsewhere in the Universe is so compelling, it's driven people with intellectual curiosity to try and compute the likelihood of life on other planets.[embed]https://www.youtube.com/watch?v=wem9EDPr3p8[/embed]One of the main ways people have tried to understand if life is prevalent in the Universe is through the Drake Equation, named after Dr. Frank Drake. He tried to come up with a way to compute the probability of the existence of other civilizations. The Drake Equation is a mainstay of the conversation around the existence of life in the Universe.The Drake Equation is a way to calculate the probability of extraterrestrial civilizations in the Milky Way that were technologically advanced to communicate. When it was created in 1961, Drake himself explained that it was really just a way of starting a conversation about extraterrestrial civilizations, rather than a definitive calculation. Still, the equation is the starting point for a lot of conversations.But the problem with the Drake equation, and with all of our attempts to understand the likelihood of life starting on other planets, is that we only have the Earth to go by. It seems like life on Earth started pretty early, and has been around for a long time. With that in mind, people have looked out into the Universe, estimated the number of planets in habitable zones, and concluded that life must be present, and even plentiful, in the Universe.But we really only know two things: First, life on Earth began a few hundred million years after the planet was formed, when it was sufficiently cool and when there was liquid water. The second thing that we know is that a few billions of years after life started, creatures appeared which were sufficiently intelligent enough to wonder about life.In 2012, two scientists published a paper which reminded us of this fact. David Spiegel, from Princeton University, and Edwin Turner, from the University of Tokyo, conducted what's called a Bayesian analysis on how our understanding of the early emergence of life on Earth affects our understanding of the existence of life elsewhere.A Bayesian analysis is a complicated matter for non-specialists, but in this paper it's used to separate out the influence of data, and the influence of our prior beliefs, when estimating the probability of life on other worlds. What the two researchers concluded is that our prior beliefs about the existence of life elsewhere have a large effect on any probabilistic conclusions we make about life elsewhere. As the authors say in the paper, "Life arose on Earth sometime in the first few hundred million years after the young planet had cooled to the point that it could support water-based organisms on its surface. The early emergence of life on Earth has been taken as evidence that the probability of abiogenesis is high, if starting from young-Earth-like conditions."A key part of all this is that life may have had a head start on Earth. Since then, it's taken about 3.5 billion years for creatures to evolve to the point where they can think about such things. So this is where we find ourselves; looking out into the Universe and searching and wondering. But it's possible that life may take a lot longer to get going on other worlds. We just don't know, but many of the guesses have assumed that abiogenesis on Earth is standard for other planets.What it all boils down to, is that we only have one data point, which is life on Earth. And from that point, we have extrapolated outward, concluding hopefully that life is plentiful, and we will eventually find it. We're certainly getting better at finding locations that should be suitable for life to arise.What's maddening about it all is that we just don't know. We keep looking and searching, and developing technology to find habitable planets and identify bio-markers for life, but until we actually find life elsewhere, we still only have one data point: Earth. But Earth might be exceptional.As Spiegel and Turner say in the conclusion of their paper, " In short, if we should find evidence of life that arose wholly idependently of us – either via astronomical searches that reveal life on another planet or via geological and biological studies that find evidence of life on Earth with a different origin from us – we would have considerably stronger grounds to conclude that life is probably common in our galaxy."With our growing understanding of Mars, and with missions like the James Webb Space Telescope, we may one day soon have one more data point with which we can refine our probabilistic understanding of other life in the Universe.Or, there could be a sadder outcome. Maybe life on Earth will perish before we ever find another living microbe on any other world.

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Posted by Nelio Inacio at 3:19 PM 0 comments

Dark Moon Discovered Orbiting Dwarf Planet Makemake

Dark Moon Discovered Orbiting Dwarf Planet Makemake:



This Hubble Space Telescope image reveals the first moon ever discovered around the dwarf planet Makemake. The tiny 100 mile-wide moon, nicknamed MK 2, is located just above Makemake in this image, and is barely visible because it is almost lost in the glare of the very bright dwarf planet. Credit: NASA, ESA, A. Parker and M. Buie (Southwest Research Institute), W. Grundy (Lowell Observatory), and K. Noll (NASA GSFC)


Planetary scientists using the Hubble Space Telescope have spotted a dark mini-moon orbiting the distant dwarf planet Makemake. The moon, nicknamed MK 2, is roughly 160 km (100 miles) wide and orbits about 20,000 km (13,000 miles) from Makemake. Makemake is 1,300 times brighter than its moon and is also much larger, at 1,400 km (870 miles) across, about 2/3rd the size of Pluto.“Our discovery of the Makemakean moon means that every formally-designated Kuiper Belt dwarf planet has at least one moon!” said Alex Parker on Twitter. Parker, along with Mark Buie, both from the Southwest Research Institute, led the same team that found the small moons of Pluto in 2005, 2011, and 2012, and they used the same Hubble technique to find MK 2. NASA says Hubble's Wide Field Camera 3 has the unique ability to see faint objects near bright ones, and together with its sharp resolution, allowed the scientists to pull the moon out from bright Makemake's glare.Previous searches for moons around Makemake came up empty, but Parker said their analysis shows the moon has a very dark surface and it is also in a nearly edge-on orbit, which made it very hard to find.This moon might be able to provide more details about Makemake, such as its mass and density. For example, when Pluto's moon Charon was discovered in 1978, astronomers were able to measure Charon’s orbit and then calculate the mass of Pluto, which showed Pluto's mass was hundreds of times smaller than originally estimated."Makemake is in the class of rare Pluto-like objects, so finding a companion is important," Parker said. "The discovery of this moon has given us an opportunity to study Makemake in far greater detail than we ever would have been able to without the companion."Parker also said the discovery of a moon for Makemake might solve a long-standing mystery about the dwarf planet. Thermal observations of Makemake by the Spitzer and Herschel space observatories seemed to show the bright world had some darker, warmer material on its surface, but other observations couldn’t confirm this.Parker said perhaps the dark material isn't on Makemake's surface, but instead is in orbit. “I modeled the emission we expect from Makemake's moon, and if the moon is very dark, it accounts for most previous thermal measurements,” he said on Twitter.The researchers will need more Hubble observations to make accurate measurements to determine if the moon's orbit is elliptical or circular, and this could help determine its origin. A tight circular orbit means that MK 2 probably formed from a collision between Makemake and another Kuiper Belt Object. If the moon is in a wide, elongated orbit, it is more likely to be a captured object from the Kuiper Belt. Many KBOs are covered with very dark material, so that might explain the dark surface of MK 2.Read the team's paper. HubbleSite info on the discovery

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Posted by Nelio Inacio at 3:19 PM 0 comments

Into the Red: Our Complete Guide to Mars Opposition 2016

Into the Red: Our Complete Guide to Mars Opposition 2016:



Mars 2014


Ready to explore the Red Planet? Starting in May, Mars invades the evening skies of the Earth, as it heads towards opposition on May 22nd. Not only does this place Mars front and center for prime time viewing, but we're headed towards a cycle of favorable oppositions, with Mars near perihelion, while Earth is near aphelion.As the name implies, Mars rises opposite to the setting Sun near opposition for us terrestrial-bound observers. The technical time of opposition — when a planet reaches a point near 180 degrees opposite to the Sun in right ascension — is, like a Full Moon, an instantaneous moment. For Mars, that moment occurs at around 10:00 Universal Time (UT) on Sunday, May 22nd. Mars makes its closest pass to the Earth eight days later on May 30th, at 75.3 million kilometers distant. This discrepancy is due to the elliptical nature of planetary orbits, as Mars races towards perihelion on October 29th, 2016, while Earth heads towards aphelion on July 4th, 2016.Not all oppositions of Mars are created equal. Mars orbits the Sun once every 687 days, and Earth catches up to Mars about once every 26 months. Mars has a markedly eccentric orbit deviating 0.093 (9.3%) from circular, meaning it can pass anywhere from 54 million to 103 million kilometers from the Earth. The oppositions of Mars follow a roughly 15 year period from one favorable cycle to the next.Opposition 2016 favors the southern hemisphere, as the retrograde loop of Mars crosses from the constellations Ophiuchus, through Scorpius into Libra and back into Scorpius this summer. Though that keeps Mars down around declination -22 degrees south, observers located at 40 degrees north will still see Mars transit about 28 degrees above the southern horizon around local midnight near opposition. Mars will appear 18.6" in size at closest approach, the largest we've seen since 2005. The 2014 opposition only reached 15.2”, and the next one on July 27th, 2018 approaches the historic 2003 opposition within an arc second, featuring Mars as a 24.3” disk.Just over a century ago, oppositions of Mars were a time of frenzied activity, as observers strained to catch fleeting moments of good seeing when details jumped out in crisp relief. Asaph Hall discovered the two tiny moons of Phobos and Deimos using the US Naval Observatory's 26" refractor during the opposition of 1877. In 1894, astronomer Percival Lowell stunned the world during opposition with reports of canals on Mars, representing what Lowell was convinced was a massive construction project undertaken by a dying alien race.Today, the months leading up to opposition represents an optimal time to send spacecraft to the Red Planet. In 2016, only the European Space Agency's ExoMars Trace Gas Orbiter seeks to make the trip.Though often termed 'the Red Planet,' Mars can take on a visual hue spanning pumpkin orange to a sickly yellow, hinting that a planetary wide dust storm is underway. What color does Mars appear to you tonight? A painter's wheel or color swatches ranging from yellow, red and orange are useful for coming up with colorful descriptors at the eyepiece. May sees the northern polar cap of Mars tipped Earthward, as late northern hemisphere summer is currently underway.Mars starts off the month of May rivaling Jupiter (which passed opposition on March 8th) at magnitude -1.5. The planet then reaches a brilliant magnitude -2.1 on the night of opposition, and doesn't drop back down below magnitude -1 until June 28th. Interestingly, Mars is also in the general vicinity of ruddy-orange Antares in 2016, the original +1 magnitude 'anti-Mars' of yore. Mars also passes one degree from Delta Scorpii on May 19th.At the eyepiece, the first surface feature you'll notice at low power is the white dot of the northern polar cap. Crank up the magnification, and dark and light surface features will begin to pop into view. Mars rotates once on its axis every 24 hours and 37 minutes, meaning you'll see about 7.5 degrees of new longitude revealed to you if you're watching at the same time each night. Sky and Telescope's Mars Profiler is an excellent resource to peg a name on just what surface features are currently turned Earthward.Sketching what you see on Mars is also fun, and can serve to sharpen your visual skills as well. Constructing a modified webcam to image the planet is also an easy project. If you've got a webcam, a telescope and a laptop, you can be off and imaging Mars tonight. Several free autostacking programs exist which allow you to select and stack images from a video sequence, the most time honored being Registax.We've modified 20$ webcams for use at the eyepiece by simply removing the lens and attaching a 1 1/12” eyepiece barrel to the front, effectively making the telescope its 'lens'. Smartphone astrophotography is reaching the point where planetary imaging is possible.Stalking the Moons of BarsoomOpposition is also a great time to cross the Martian moons of Phobos and Deimos off of your life list. Phobos and Deimos both shine at magnitude +12 and neither would present much of a problem, were it not for the glare of nearby Mars at 14 magnitudes and 400,000 times brighter. Phobos and Deimos never stray more than 18” and 54” from the limb of Mars, respectively.Phobos orbits Mars once every 7.7 hours, and Deimos takes 30.4 hours to complete one circuit of the Red Planet. A great tool to know just when a particular moon is at greatest elongation is a desktop planetarium program such as Stellarium or Starry Night. Use SETI's Ring-Moon Systems Node tool to generate a handy 'corkscrew chart' of the Martian moons.You'll need to either put Mars just out of the field of view to spy the planet's moons, or use an occulting bar eyepiece to block its glare. A tiny strip of foil attached to an eyepiece will do the job.Finally: Ever seen Mars... in the daytime? We completed this unusual feat of visual athletics with binoculars back in 2005, using the nearby Moon as a guide. Fast forward to 2016, and the waning Moon one day past Full passes seven degrees from Mars... on the night of opposition. Southern hemisphere viewers have the best shot at this on the morning of May 22nd, as Mars and the Moon set to the west, just after the Sun rises in the east.This opposition 2016 ushers in the start of a series of great passes over the next few years, climaxing in 2018. Don't miss it!

The post Into the Red: Our Complete Guide to Mars Opposition 2016 appeared first on Universe Today.

Posted by Nelio Inacio at 3:18 PM 0 comments
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