Astronomy Archives

August 8, 2017 by Matt Williams

Standford Team Creates mDOT, a Mini-Starshade for Exoplanet Research

The new DARKNESS camera developed by an international team of researchers will allow astronomers to directly study nearby exoplanets. Credit: Stanford/SRL

NASA has turned a lot of heads in recent years thanks to its New Worlds Mission concept – aka. Starshade. Consisting of a giant flower-shaped occulter, this proposed spacecraft is intended to be deployed alongside a space telescope (most likely the James Webb Space Telescope). It will then block the glare of distant stars, creating an artificial eclipse to make it easier to detect and study planets orbiting them.

The only problem is, this concept is expected to cost a pretty penny – an estimated $750 million to $3 billion at this point! Hence why Stanford Professor Simone D’Amico (with the help of exoplanet expert Bruce Macintosh) is proposing a scaled down version of the concept to demonstrate its effectiveness. Known as mDot, this occulter will do the same job, but at a fraction of the cost.

The purpose behind an occulter is simple. When hunting for exoplanets, astronomers are forced to rely predominantly on indirected methods – the most common being the Transit Method. This involves monitoring stars for dips in luminosity, which are attributed to planets passing between them and the observer. By measuring the rate and the frequency of these dips, astronomers are able to determine the sizes of exoplanets and their orbital periods.

As Simone D’Amico, whose lab is working on this eclipsing system, explained in a Stanford University press statement:

“With indirect measurements, you can detect objects near a star and figure out their orbit period and distance from the star. This is all important information, but with direct observation you could characterize the chemical composition of the planet and potentially observe signs of biological activity – life.”

However, this method also suffers from a substantial rate of false positives and generally requires that part of the planet’s orbit intersect a line-of-sight between the host star and Earth. Studying the exoplanets themselves is also quite difficult, since the light coming from the star is likely to be several billion times brighter than the light being reflected off the planet.

The ability to study this reflected light is of particular interest, since it would yield valuable data about the exoplanets’ atmospheres. As such, several key technologies are being developed to block out the interfering light of stars. A spacecraft equipped with an occulter is one such technology. Paired with a space telescope, this spacecraft would create an artificial eclipse in front of the star so objects around it (i.e. exoplanets) can be clearly seen.

But in addition to the significant cost of building one, there is also the issue of size and deployment. For such a mission to work, the occulter itself would need to be about the size of a baseball diamond – 27.5 meters (90 feet) in diameter. It would also need to be separated from the telescope by a distance equal to multiple Earth diameters and would have to be deployed beyond Earth’s orbit. All of this adds up to a rather pricey mission!

Artist’s impression of the mDOT system. Much like the moon in a solar eclipse, one spacecraft would block the light from the star, allowing the other to observe objects near that star. Credit: Space Rendezvous Laboratory/Stanford University

As such, D’Amico – an assistant professor and the head of the Space Rendezvous Laboratory (SRL) at Stanford – and and Bruce Macintosh (a Stanford professor of physics) teamed up to create a smaller version called the Miniaturized Distributed Occulter/Telescope (mDOT). The primary purpose of mDOT is to provide a low-cost flight demonstration of the technology, in the hopes of increasing confidence in a full-scale mission.

As Adam Koenig, a graduate student with the SRL, explained:

“So far, there has been no mission flown with the degree of sophistication that would be required for one of these exoplanet imaging observatories. When you’re asking headquarters for a few billion dollars to do something like this, it would be ideal to be able to say that we’ve already flown all of this before. This one is just bigger.”

Consisting of two parts, the mDOT system takes advantage of recent developments in miniaturization and small satellite (smallsat) technology. The first is a 100-kg microsatellite that is equipped with a 3-meter diameter starshade. The second is a 10-kg nanosatellite that carries a telescope measuring 10 cm (3.937 in) in diameter. Both components will be deployed in high Earth orbit with a nominal separation of less than 1,000 kilometers (621 mi).

With the help of colleagues from the SRL, the shape of mDOT’s starshade was reformulated to fit the constraints of a much smaller spacecraft. As Koenig explained, this scaled down and specially-designed starshade will be able to do the same job as the large-scale, flower-shaped version – and on a budget!

Simone D’Amico’s Space Rendezvous Laboratory, pictured inside the room where they test space navigation in highly realistic illumination conditions. Credit: Space Rendezvous Laboratory/Stanford University

“With this special geometric shape, you can get the light diffracting around the starshade to cancel itself out,” he said. “Then, you get a very, very deep shadow right in the center. The shadow is deep enough that the light from the star won’t interfere with observations of a nearby planet.”

However, since the shadow created by mDOT’s starshade is only tens of centimeters in diameter, the nanosatellite will have do some careful maneuvering to stay within it. For this purpose, D’Amico and the SRL also designed an autonomous system for the nanosatellite, which would allow it to conduct formation maneuvers with the starshade, break formation when needed, and rendezvous with it again later.

An unfortunate limitation to the technology is the fact that it won’t be able to resolve Earth-like planets. Especially where M-type (red dwarf) stars are concerned, these planets are likely to orbit too close to their parent stars to be observed clearly. However, it will be able to resolve Jupiter-sized gas giants and help characterize exozodiacal dust concentrations around nearby stars – both of which are priorities for NASA.

In the meantime, D’Amico and his colleagues will be using the Testbed for Rendezvous and Optical Navigation (TRON) to test their mDOT concept. This facility was specially-built by D’Amico to replicate the types of complex and unique illumination conditions that are encountered by sensors in space. In the coming years, he and his team will be working to ensure that the system works before creating an eventual prototype.

*Artist’s concept of the prototype starshade, a giant structure designed to block the glare of stars so that future space telescopes can take pictures of planets. Credit: NASA/JPL*

As D’Amico said of the work he and his colleagues at the SNL perform:

“I’m enthusiastic about my research program at Stanford because we’re tackling important challenges. I want to help answer fundamental questions and if you look in all current direction of space science and exploration – whether we’re trying to observe exoplanets, learn about the evolution of the universe, assemble structures in space or understand our planet – satellite formation-flying is the key enabler.”

Other projects that D’Amico and the SNL are currently engaged in include developing larger formations of tiny spacecraft (aka. “swarm satellites”). In the past, D’Amico has also collaborated with NASA on such projects as GRACE – a mission that mapped variations in Earth’s gravity field as part of the NASA Earth System Science Pathfinder (ESSP) program – and TanDEM-X, an SEA-sponsored mission which yielded 3D maps of Earth.

These and other projects which seek to leverage miniaturization for the sake of space exploration promise a new era of lower costs and greater accessibility. With applications ranging from swarms of tiny research and communications satellites to nanocraft capable of making the journey to Alpha Centauri at relativistic speeds (Breakthrough Starshot), the future of space looks pretty promising!

Be sure to check out this video of the TRON facility too, courtesy of Standford University:

Further Reading: Standford University

August 7, 2017August 7, 2017 by Tammy Plotner

Messier 53 – the NGC 5024 Globular Cluster

Messier 53, as imaged by the Hubble Space Telescope. Credit: ESA/Hubble & NASA

Welcome back to Messier Monday! In our ongoing tribute to the great Tammy Plotner, we take a look at globular cluster known as Messier 53!

During the 18th century, famed French astronomer Charles Messier noted the presence of several “nebulous objects” in the night sky. Having originally mistaken them for comets, he began compiling a list of these objects so others would not make the same mistake he did. In time, this list (known as the Messier Catalog) would come to include 100 of the most fabulous objects in the night sky.

One of these objects is Messier 53, a globular cluster located in the northern Coma Berenices constellation. Located about 58,000 light years from the Solar System, it is almost equidistant from Galactic Center (about 60,000 light years). As Messier Objects go, it is relatively easy to find since it lies in the same area of the sky as Arcturus, the fourth brightest star in the night sky.

Description:

Heading towards us at a speed of 112 kilometers per second, globular cluster M53 is one of the furthest distant globular clusters in our Milky Way halo and lay almost equally distant between our solar system and the galactic center. This 220 light year diameter ball of stars in tightly compacted towards its core – where low metal is the name of the game and RR Lyra type variable stars once ruled. But recent studies have found that there are some new kids on the block. The blue stragglers…

According to G. Beccari (et al) the population of these definitely appears to violate standard theories of stellar evolution. And there not just a few blues… There’s a whole host of them. As Beccari noted in a 2008 study:

“We used a proper combination of high-resolution and wide-field multiwavelength observations collected at three different telescopes (HST, LBT, and CFHT) to probe the blue straggler star (BSS) population in the globular cluster M53. Almost 200 BSSs have been identified over the entire cluster extension. We have also used this database to construct the radial star density profile of the cluster; this is the most extended and accurate radial profile ever published for this cluster, including detailed star counts in the very inner region. A deviation from the model is noted in the most external region of the cluster. This feature needs to be further investigated in order to address the possible presence of a tidal tail in this cluster.”

Is this possible? Then take a closer look into this research. One where a millisecond pulsar was discovered inside. As S.R. Kulkarni (et al) indicated in a 1991 study:

“Millisecond pulsars are conventionally assumed to be spun up through the action of binary companions, although some subsequently lose their companions and appear as isolated pulsars. Such objects should therefore be more numerous in dense stellar systems. We report here the surprising discovery of two pulsars in low-density globular clusters: one is a single 10-ms pulsar (1639+36) in M13 (NGC 6205), the other a 33-ms pulsar (1310+18) in a 256-d binary in M53 (NGC 5024). Their ages, inferred from their luminosities and constraints on their period derivatives, seem to be 10 9 years, significantly greater than previously reported ages ( ! 10 8 years) of cluster pulsars. The implied birth rate is inconsistent with the conventional two-body tidal capture model, suggesting that an alternative mechanism such as tidal capture between primordial binaries and a reservoir of (hundreds of) primordial neutron stars may dominate the production of tidal binaries in such clusters. The period derivative of PSR1639+36 is surprisingly small, and may be corrupted by acceleration due to the mean gravitational potential of the cluster.”

*The Messier 53 globular star cluster. Credit: Ole Nielsen*

History of Observation:

This globular cluster was first discovered on February 3, 1775 by Johann Elert Bode, but independently recovered on February 26, 1777 by Charles Messier who writes:

“Nebula without stars discovered below & near Coma Berenices, a little distant from the star 42 in that constellation, according to Flamsteed. This nebula is round and conspicuous. The Comet of 1779 was compared directly with this nebula, & M. Messier has reported it on the chart of that comet, which will be included in the volume of the Academy for 1779. Observed again April 13, 1781: It resembles the nebula which is below Lepus [M79].”

Sir William Herschel would revisit M53, but he did not publish his findings when studying Messier objects. Very seldom did Herschel wax poetic in his writings, but of this particular object he said: “A cluster of very close stars; one of the most beautiful objects I remember to have seen in the heavens. The cluster appears under the form of a solid ball, consisting of small stars, quite compressed into one blaze of light, with a great number of loose ones surrounding it, and distinctly visible in the general mass.”

He would return again in later years to include in his notes: “From what has been said it is obvious that here the exertion of a clustering power has brought the accumulation and artificial construction of these wonderful celestial objects to the highest degree of mysterious perfection.”

*The Messier 53 globular cluster. Credit: NASA/ESA/Hubble*

Although it did not touch Sir John Herschel quite so much, M53 also engaged Admiral Smyth who wrote:

“A globular cluster, between Berenice’s tresses and the Virgin’s left hand, with a coarse pair of telescopic stars in the sf [south following, SE] quadrant, and a single one in the sp [south preceding, SW]. This is a brilliant mass of minute stars, from the 11th to the 15th magnitude, and from thence to gleams of star-dust, with stragglers to the np [north preceding, NW], and pretty diffused edges. From the blaze at the centre, it is evidently a highly compressed ball of stars, whose law of aggregation into so dense and compact a mass, is utterly hidden from our imperfect senses. It was enrolled by Messier in 1774 as No. 53, and resolved into stars by Sir W. Herschel. The contemplation of so beautiful an object, cannot but set imagination to work, though the mind may be soon lost in astonishment at the stellar dispositions of the great Creator and Maintainer. Thus, in reasoning by analogy, these compressed globes of stars confound conjecture as to the models in which the mutual attractions are prevented from causing the universal destruction of their system. Sir John Herschel thinks, that no pressure can be propagated through a cluster of discrete stars; whence it would follow, that the permanence of its form must be maintained in a way totally different from that which our reasoning suggest. Before quitting this interesting ball of innumerable worlds, I may mention that it was examined by Sir John Herschel, with Mr. Baily, in the 20-foot reflector; and that powerful instrument showed the cluster with curved appendages of stars, like the short claws of a crab running out from the main body. A line through Delta and Epsilon Virginis, northward, meeting another drawn from Arcturus to Eta Bootis, unite upon this wonderful assemblage; or it is also easily found by its being about 1 deg northeast of 42 Comae Berenices, the alignment of which is already given.”

Locating Messier 53:

M53 can be easily found just about a degree northeast of 42 Alpha Comae Berenices, a visual binary star. To located Alpha, draw a mental line from Arcturus via Eta Bootis where you’ll see it about a fist width west. Alternately you can starhop from Gamma Viginis to Delta and on to Epsilon where you can locate M53 approximately 4 fingerwidths to the north/northeast.

To see this small globular cluster in binoculars will require dark skies and it will appear very small, like a large, out of focus star. In small telescopes it will appear almost cometary – and thus why Messier cataloged these objects! However, with telescopes approaching the 6″ range, resolution will begin and larger telescopes will shatter this gorgeous globular cluster. Requires dark skies.

*The location of Messier 53 in the northern Coma Berenices constellation. Credit: IAU and Sky & Telescope magazine (Roger Sinnott & Rick Fienberg)*

A ball of worlds… What a unique description! May you enjoy your observations as well!

And here are the quick facts on this Messier Object to help you get started!

Object Name: Messier 53
Alternative Designations: M53, NGC 5024
Object Type: Class V Globular Cluster
Constellation: Coma Berenices
Right Ascension: 13 : 12.9 (h:m)
Declination: +18 : 10 (deg:m)
Distance: 58.0 (kly)
Visual Brightness: 7.6 (mag)
Apparent Dimension: 13.0 (arc min)

We have written many interesting articles about Messier Objects here at Universe Today. Here’s Tammy Plotner’s Introduction to the Messier Objects, , M1 – The Crab Nebula, M8 – The Lagoon Nebula, and David Dickison’s articles on the 2013 and 2014 Messier Marathons.

Be to sure to check out our complete Messier Catalog. And for more information, check out the SEDS Messier Database.

Sources:

August 4, 2017August 20, 2017 by Matt Williams

NASA Voyager Probes Still Going Strong After 40 Years

Earth's Greatest Hits: the Golden Record attached to the Voyager 1 and 2 spacecraft. Credit: NASA/JPL.

Forty years ago, the Voyager 1 and 2 missions began their journey from Earth to become the farthest-reaching missions in history. In the course of their missions, the two probes spent the next two decades sailing past the gas giants of Jupiter and Saturn. And while Voyager 1 then ventured into the outer Solar System, Voyager 2 swung by Uranus and Neptune, becoming the first and only probe in history to explore these worlds.

This summer, the probes will be marking the fortieth anniversary of their launch – on September 5th and August 20th, respectively. Despite having traveled for so long and reaching such considerable distances from Earth, the probes are still in contact with NASA and sending back valuable data. So in addition to being the most distant missions from Earth, they are the longest-running mission in history.

In addition to their distance and longevity, the Voyager spacecraft have also set numerous other records for robotic space missions. For example, in 2012, the Voyager 1 probe became the first and only spacecraft to have entered interstellar space. Voyage 2, meanwhile, is the only probe that has explored all four of the Solar System’s gas/ice giants – Jupiter, Saturn, Uranus and Neptune.

Voyager 2 Mission — The launch of the Voyager 2 probe, which took place on August 20th, 1977. Credit: NASA

Their discoveries also include the first active volcanoes beyond Earth – on Jupiter’s moon Io – the first evidence of a possible subsurface ocean on Europa, the dense atmosphere around Titan (the only body beyond Earth with a dense, nitrogen-rich atmosphere), the craggy surface of Uranus’ “Frankenstein Moon” Miranda, and the ice plume geysers of Neptune’s largest moon, Triton.

These accomplishments have had immeasurable benefits for planetary science, astronomy and space exploration. They’ve also paved the way for future missions, such as the Galileo and Juno probes, the Cassini-Huygens mission, and the New Horizons spacecraft. As Thomas Zurbuchen, the associate administrator for NASA’s Science Mission Directorate (SMD), said in a recent press statement:

“I believe that few missions can ever match the achievements of the Voyager spacecraft during their four decades of exploration. They have educated us to the unknown wonders of the universe and truly inspired humanity to continue to explore our solar system and beyond.”

But what is perhaps most memorable about the Voyager missions is the special cargo they carry. Each spacecraft carries what is known as the Golden Record, a collection of sounds, pictures and messages that tell of Earth, human history and culture. These records were intended to serve as a sort of time capsule and/or message to any civilizations that retrieved them, should they ever be recovered.

*Each of the two Voyager spacecraft launched in 1977 carry a 12-inch gold-plated phonograph record with images and sounds from Earth. Credit: NASA*

As noted, both ships are still in contact with NASA and sending back mission data. The Voyager 1 probe, as of the writing of this article, is about 20.9 billion km (13 billion mi; 140 AU) from Earth. As it travels northward out of the plane of the planets and into interstellar space, the probe continues to send back information about cosmic rays – which are about four times as abundant in interstellar space than around Earth.

From this, researchers have learned that the heliosphere – the region that contains the Solar System’s planets and solar wind – acts as a sort of radiation shield. Much in the say that Earth’s magnetic field protects us from solar wind (which would otherwise strip away our atmosphere), the heliopause protects the Solar planets from atomic nuclei that travel at close to the speed of light.

Voyager 2, meanwhile, is currently about 17.7 billion km (11 billion mi; 114.3 AU) from Earth. It is traveling south out of the plane of the planets, and is expected to enter interstellar space in a few years. And much like Voyager 1, it is also studying how the heliosphere interacts with the surroundings interstellar medium, using a suite of instruments that measure charged particles, magnetic fields, radio waves and solar wind plasma.

Once Voyager 2 crosses into interstellar space, both probes will be able to sample the medium from two different locations simultaneously. This is expected to tell us much about the magnetic environment that encapsulates our system, and will perhaps teach us more about the history and formation of the Solar System. On top of that, it will let us know what kinds of hazards a possible interstellar mission will have to contend with.

Illustration showing how NASA’s Hubble Space Telescope is looking along the paths of NASA’s Voyager 1 and 2 spacecraft as they journey through the solar system and into interstellar space. Credit: NASA/ESA/Z. Levy (STScI)

The fact that the two probes are still active after all this time is nothing short of amazing. As Edward Stone – the David Morrisroe Professor of Physics at Caltech, the former VP and Director of NASA’s Jet Propulsion Laboratory, and the Voyager project scientist – said:

“None of us knew, when we launched 40 years ago, that anything would still be working, and continuing on this pioneering journey. The most exciting thing they find in the next five years is likely to be something that we didn’t know was out there to be discovered.”

Keeping the probes going has also been a challenge since the amount of power they generate decreases at a rate of about four watts per year. This has required that engineers learn how to operate the twin spacecraft with ever-decreasing amounts of power, which has forced them to consult documents that are decades old in order to understand the probes’ software and command functions.

Luckily, it has also given former NASA engineers who worked on the Voyager probes the opportunity to offer their experience and expertise. At present, the team that is operating the spacecraft estimate that the probes will run out of power by 2030. However, they will continue to drift along their trajectories long after they do so, traveling at a speed of 48,280 km per hour (30,000 mph) and covering a single AU every 126 days.

*The Voyager 1 spacecraft has started to transverse what JPL has dubbed as a “cosmic purgatory” between our solar system – and interstellar space. Credit: NASA/JPL*

At this rate, they will be within spitting distance of the nearest star in about 40,000 years, and will have completed an orbit of the Milky Way within 225 million years. So its entirely possible that someday, the Golden Records will find their way to a species capable of understanding what they represent. Then again, they might find their way back to Earth someday, informing our distant, distant relatives about life in the 20th century.

And if the craft avoid any catastrophic collisions and can survive in the interstellar medium of space, it is likely that they will continue to be emissaries for humanity long after humanity is dead. It’s good to leave something behind!

Further Reading: NASA

August 4, 2017February 7, 2021 by Matt Williams

Bad News For Proxima b: An Earth-Like Atmosphere Might Not Survive There

Artist’s impression of Proxima b, which was discovered using the Radial Velocity method. Credit: ESO/M. Kornmesser

Back in of August of 2016, the existence of an Earth-like planet right next door to our Solar System was confirmed. To make matters even more exciting, it was confirmed that this planet orbits within its star’s habitable zone too. Since that time, astronomers and exoplanet-hunters have been busy trying to determine all they can about this rocky planet, known as Proxima b. Foremost on everyone’s mind has been just how likely it is to be habitable.

However, numerous studies have emerged since that time that indicate that Proxima b, given the fact that it orbits an M-type (red dwarf), would have a hard time supporting life. This was certainly the conclusion reached in a new study led by researchers from NASA’s Goddard Space Flight Center. As they showed, a planet like Proxima b would not be able to retain an Earth-like atmosphere for very long.

Red dwarf stars are the most common in the Universe, accounting for an estimated 70% of stars in our galaxy alone. As such, astronomers are naturally interested in knowing just how likely they are at supporting habitable planets. And given the distance between our Solar System and Proxima Centauri – 4.246 light years – Proxima b is considered ideal for studying the habitability of red dwarf star systems.

*This infographic compares the orbit of the planet around Proxima Centauri (Proxima b) with the same region of the Solar System. Credit: Pale Red Dot*

On top of all that, the fact that Proxima b is believed to be similar in size and composition to Earth makes it an especially appealing target for research. The study was led by Dr. Katherine Garcia-Sage of NASA’s Goddard Space Flight Center and the Catholic University of America in Washington, DC. As she told Universe Today via email:

“So far, not many Earth-sized exoplanets have been found orbiting in the temperate zone of their star. That doesn’t mean they don’t exist – larger planets are found more often because they are easier to detect – but Proxima b is of interest because it’s not only Earth-sized and at the right distance from its star, but it’s also orbiting the closest star to our Solar System.”

For the sake of determining if Proxima b could be habitable, the research team sought to address the chief concerns facing rocky planets that orbit red dwarf stars. These include the planet’s distance from its stars, the variability of red dwarfs, and the presence (or absence) of magnetic fields. Distance is of particular importance since habitable zones (aka. temperate zones) around red dwarfs are much closer and tighter.

“Red dwarfs are cooler than our own Sun, so the temperate zone is closer to the star than Earth is to the Sun,” said Dr. Garcia-Sage. “But these stars may be very magnetically active, and being so close to a magnetically active star means that these planets are in a very different space environment than what the Earth experiences. At those distances from the star, the ultraviolet and x-ray radiation may be quite large. The stellar wind may be stronger. There could be stellar flares and energetic particles from the star that ionize and heat the upper atmosphere.”

*At one time, Mars had a magnetic field similar to Earth, which prevented its atmosphere from being stripped away. Credit: NASA*

In addition, red dwarf stars are known for being unstable and variable in nature when compared to our Sun. As such, planets orbiting in close proximity would have to contend with flare ups and intense solar wind, which could gradually strip away their atmospheres. This raises another important aspect of exoplanet habitability research, which is the presence of magnetic fields.

To put it simply, Earth’s atmosphere is protected by a magnetic field that is driven by a dynamo effect in its outer core. This “magnetosphere” has prevented solar wind from stripping our atmosphere away, thus giving life a chance to emerge and evolve. In contrast, Mars lost its magnetosphere roughly 4.2 billion years ago, which led to its atmosphere being depleted and its surface becoming the cold, desiccated place it is today.

To test Proxima b’s potential habitability and capacity to retain liquid surface water, the team therefore assumed the presence of an Earth-like atmosphere and a magnetic field around the planet. They then accounted for the enhanced radiation coming from Proxima b. This was provided by the Harvard Smithsonian Center for Astrophysics (CfA), where researchers determined the ultraviolet and x-ray spectrum of Proxima Centauri for this project.

From all of this, they constructed models that began to calculate the rate of atmospheric loss, using Earth’s atmosphere as a template. As Dr. Garcia-Sage explained:

“At Earth, the upper atmosphere is ionized and heated by ultraviolet and x-ray radiation from the Sun. Some of these ions and electrons escape from the upper atmosphere at the north and south poles. We have a model that calculates how fast the upper atmosphere is lost through these processes (it’s not very fast at Earth)… We then used that radiation as the input for our model and calculated a range of possible escape rates for Proxima Centauri b, based on varying levels of magnetic activity.”

Artist’s impression of the surface of the planet Proxima b orbiting the red dwarf star Proxima Centauri. The double star Alpha Centauri AB is visible to the upper right of Proxima itself. Credit: ESO

What they found was not very encouraging. In essence, Proxima b would not be able to retain an Earth-like atmosphere when subjected to Proxima Centauri’s intense radiation, even with the presence of a magnetic field. This means that unless Proxima b has had a very different kind of atmospheric history than Earth, it is most likely a lifeless ball of rock.

However, as Dr. Garcia-Sage put it, there are other factors to consider which their study simply can’t account for:

“We found that atmospheric losses are much stronger than they are at Earth, and the for high levels of magnetic activity that we expect at Proxima b, the escape rate was fast enough that an entire Earth-like atmosphere could be lost to space. That doesn’t take into account other things like volcanic activity or impacts with comets that might be able to replenish the atmosphere, but it does mean that when we’re trying to understand what processes shaped the atmosphere of Proxima b, we have to take into account the magnetic activity of the star. And understanding the atmosphere is an important part of understanding whether liquid water could exist on the surface of the planet and whether life could have evolved.”

So it’s not all bad news, but it doesn’t inspire a lot of confidence either. Unless Proxima b is a volcanically-active planet and subject to a lot of cometary impacts, it is not likely be temperate, water-bearing world. Most likely, its climate will be analogous to Mars – cold, dry, and with water existing mostly in the form of ice. And as for indigenous life emerging there, that’s not too likely either.

These and other recent studies have painted a rather bleak picture about the habitability of red dwarf star systems. Given that these are the most common types of stars in the known Universe, the statistical likelihood of finding a habitable planet beyond our Solar System appears to be dropping. Not exactly good news at all for those hoping that life will be found out there within their lifetimes!

But it is important to remember that what we can say definitely at this point about extra-solar planets is limited. In the coming years and decades, next-generation missions – like the James Webb Space Telescope (JWST) and the Transiting Exoplanet Survey Satellite (TESS) – are sure to paint a more detailed picture. In the meantime, there’s still plenty of stars in the Universe, even if most of them are extremely far away!

Further Reading: The Astrophysical Journal Letters

August 3, 2017August 3, 2017 by Matt Williams

Hubble Eyes Stratosphere Around a Very Hot, Watery Jupiter!

Artist's concept of the hot Jupiter WASP-121b, which presents the best evidence yet of a stratosphere on an exoplanet - generated using Engine House VFX. Credit: Bristol Science Centre/University of Exeter

Extra-solar planet discoveries have been exploding in recent years. In fact, as of Aug. 1st, 2017, astronomers have identified 3,639 exoplanets in 2,729 planetary systems and 612 multiple planetary systems. And while the majority of these have been discovered by Kepler – which has detected a total of 5,017 candidates and confirmed the existence of 2,494 exoplanets since 2009 – other instruments have played an important role in these discoveries as well.

This includes the Hubble Space Telescope, which in recent years has been dedicated to the detection of atmospheres around distant planets. Most recently, it was used in a survey that produced the strongest evidence to date for the existence of a stratosphere – a layer of atmosphere in which temperature increases with altitude – around a gas giant located about 900 light-years from our Solar System.

The study, titled “An ultrahot gas-giant exoplanet with a stratosphere“, recently appeared in the journal Nature. Led by Thomas Evans, a Research Fellow from the Astrophysics Group at the University of Exeter, the team relied on data provided by NASA’s Hubble Space Telescope to study a planet known as WASP-121b, a gas giant that orbits a yellow-white star that is slightly larger than our own.

*The top of the planet’s atmosphere is heated to a blazing 2,500 °C (4,600 °F), hot enough to boil some metals. Credit: NASA/ESA/G. Bacon (STSci)*

The planet itself has roughly 1.2 times the mass of Jupiter, has a radius that is about 1.9 times that of Jupiter, and has an orbital period of just 1.3 days. This is due to its close proximity to its sun, which makes it a particularly “Hot Jupiter”. In fact, if this exoplanet were any closer to its star, it is estimated that WASP-121’s gravity would begin to tear it apart.

It is also this close proximity that super-heats the planet’s atmosphere, driving temperatures up to 2,500 °C (4,600 °F). As Mark Marley, a researcher with NASA’s Ames Research Center and a co-author on the study, indicated in a NASA press statement:

“This result is exciting because it shows that a common trait of most of the atmospheres in our solar system — a warm stratosphere — also can be found in exoplanet atmospheres. We can now compare processes in exoplanet atmospheres with the same processes that happen under different sets of conditions in our own solar system.”

Whereas Hubble has found possible signs of stratospheres around WASP-33b and other hot Jupiters in the past, this new study presents the strongest evidence to date for the existence of an exoplanet stratosphere. The reason for this has to do with the spectrographic data obtained by Hubble of WASP-121b’s atmosphere, which indicated the presence of water vapor – which is a first as far as hot-Jupiter’s are concerned.

As Tom Evans – also a Research Fellow at the University of Exeter and the lead author on the paper – explained, these findings confirmed something that astronomers have suspected for some time. “Theoretical models have suggested stratospheres may define a distinct class of ultra-hot planets, with important implications for their atmospheric physics and chemistry,” he said. “Our observations support this picture.”

To study WASP-121b’s stratosphere, the team relied on spectroscopic data gathered by Hubble’s Wide Field Camera 3. After analyzing the different wavelengths that were part of WASP-121b’s light cure, they noted that certain wavelengths were glowing rather brightly in the infrared band. This, they concluded, was due to the presence of water vapor at the top of the planet’s atmosphere.

“The emission of light from water means the temperature is increasing with height,” Tiffany Kataria, one of the co-authors on the study from NASA’s Jet Propulsion Laboratory, said. “We’re excited to explore at what longitudes this behavior persists with upcoming Hubble observations.”

Beyond being the most convincing case so far of an exoplanet having a stratosphere, WASP-121b is also interesting because of just how hot this hot Jupiter is. Based on their data, the team concluded that temperatures in the atmosphere increased with altitude – a defining characteristic of a stratosphere. In Earth’s stratosphere, this process is driven by ozone, which traps the Sun’s ultraviolet light and raises the temperature of the surrounding molecules.

*Artist’s concept of “hot Jupiter” exoplanet, a gas giant that orbits very close to its star. Credit: NASA/JPL-Caltech)*

However, the temperature of Earth’s stratosphere does not exceed 270 K (-3°C; 26.6°F). When one considers other Solar Planets that also have stratosphere’s – like Saturn’s moon Titan, which experiences heating due to the interaction of solar radiation, energetic particles and methane – temperatures don’t change by more than 56 °C (100 °F). But in the case of WASP-121b, temperatures in the stratosphere increase by about 560 °C (1,000 °F).

Not even Venus, the hottest planet in the Solar System, can compete with that! On Earth’s “Sister Planet”, temperatures remain steady at about 735 K (462 °C; 863 °F), which is hot enough to melt lead. But on WASP-121b, temperatures reach over four times as high! This means the planet’s atmosphere is hot enough to melt stainless steel and other metals – like beryllium, platinum and zirconium.

At present, scientists do not now what chemicals are driving this temperature increase. Some possibilities have been suggested though, such as vanadium oxide and titanium oxide. Not only are these compounds believed to be common to brown dwarfs (aka. “failed stars”, which have much in common with gas giants), they also require the hottest temperatures possible in order to keep them in a gaseous state.

In any case, this distant gas giant has proven to be an interesting case study. In the future, research into this and other “super-hot Jupiters” is likely to challenge and expand our current understanding of how atmospheric forms and behave over time.

Further Reading: NASA, Nature

August 3, 2017 by Matt Williams

Need a Job? NASA is Looking for a New Planetary Protection Officer

In the future, planetary protection (where we ensure that missions do not contaminate other words with Earth-borne organisms) will be especially important. Credit: NASA, JPL-Caltech

NASA has always had its fingers in many different pies. This should come as no surprise, since the advancement of science and the exploration of the Universe requires a multi-faceted approach. So in addition to studying Earth and distant planets, the also study infectious diseases and medical treatments, and ensuring that food, water and vehicles are safe. But protecting Earth and other planets from contamination, that’s a rather special job!

For decades, this responsibility has fallen to the NASA Office of Planetary Protection, the head of which is known as the Planetary Protection Officer (PPO). Last month, NASA announced that it was looking for a new PPO, the person whose job it will be to ensure that future missions to other planets don’t contaminate them with microbes that have come along for the ride, and that return missions don’t bring extra-terrestrial microbes back to Earth.

Since the beginning of the Space Age, federal agencies have understood that any and all missions carried with them the risk of contamination. Aside from the possibility that robotic or crewed missions might transport Earth microbes to foreign planets (and thus disrupt any natural life cycles there), it was also understood that missions returning from other bodies could bring potentially harmful organisms back to Earth.

The US won the space race against its adversary, the USSR. The image of the American flag planted on the Moon, being saluted by an American astronaut, must have caused great consternation in the Kremlin. Will SpaceX's mission to Mars cause the same consternation? Will Russia and other nations use the mission to remind the US of their Outer Space Treaty obligations? Image: NASA — *Back when NASA was still in the midst of the Apollo Program, it was decided that steps needed to be taken to ensure that missions to other bodies did not cause contaminated. Credit: NASA*

As such, the Office of Planetary Protection was established in 1967 to ensure that these risks were mitigated using proper safety and sterilization protocols. This was shortly after the United Nation’s Office of Outer Space Affairs (UNOOSA) drafted the Outer Space Treaty, which was signed by the United States, the United Kingdom, and the Soviet Union (as of 2017, 107 countries have become party to the treaty).

The goals of the Office of Planetary Protection are consistent with Article IX of the Outer Space Treaty; specifically, the part which states:

“States Parties to the Treaty shall pursue studies of outer space, including the Moon and other celestial bodies, and conduct exploration of them so as to avoid their harmful contamination and also adverse changes in the environment of the Earth resulting from the introduction of extraterrestrial matter and, where necessary, shall adopt appropriate measures for this purpose.”

The office and its practices are also consistent with NASA’s internal policies. These include NASA Policy Directive (NPR) 8020.12D: “Planetary Protection Provisions for Robotic Extraterrestrial Missions”, and 8020.7: “Biological Contamination Control for Outbound and Inbound Planetary Spacecraft”, which require that all missions comply with protection procedures.

For decades, these directives have been followed to ensure that missions to the Moon, Mars and the Outer Solar System did not threaten these extra-terrestrial environments. For example, after eight years studying Jupiter and its largest moons, the Galileo probe was deliberately crashed into Jupiter’s atmosphere to ensure that none of its moons (which could harbor life beneath their icy surfaces) were contaminated by Earth-based microbes.

*Artist’s concept of the Galileo space probe passing through the Jupiter system. Credit: NASA*

The same procedure will be followed by the Juno mission, which is currently in orbit around Jupiter. Barring a possible mission extension, the probe is scheduled to be deorbited after conducting a total of 12 orbits of the gas giant. This will take place in July of 2018, at which point, the craft will burn up to avoid contaminating the Jovian moons of Europa, Ganymede and Callisto.

The same holds true for the Cassini spacecraft, which is currently passing between Saturn and its system of rings, as part of the mission’s Grand Finale. When this phase of its mission is complete – on September 15th, 2017 – the probe will be deorbited into Saturn’s atmosphere to prevent any microbes from reaching Enceladus, Titan, Dione, moons that may also support life in their interiors (or in Titan’s case, even on its surface!)

To be fair, the position of a Planetary Protection Officer is not unique to NASA. The European Space Agency (ESA), the Japanese Aerospace and Exploration Agency (JAXA) and other space agencies have similar positions. However, it is only within NASA and the ESA that it is considered to be a full-time job. The position is held for three years (with a possible extension to five) and is compensated to the tune of $124,406 to $187,000 per year.

The job, which can be applied for on USAJOBS.gov (and not through the Office of Planetary Protection), will remain open until August 18th, 2017. According to the posting, the PPO will be responsible for:

Leading planning and coordinating activities related to NASA mission planetary protection needs.
Leading independent evaluation of, and providing advice regarding, compliance by robotic and human spaceflight missions with NASA planetary protection policies, statutory requirements and international obligations.
Advising the Chief, SMA and other officials regarding the merit and implications of programmatic decisions involving risks to planetary protection objectives.
In coordination with relevant offices, leading interactions with COSPAR, National Academies, and advisory committees on planetary protection matters.
Recommending and leading the preparation of new or revised NASA standards and directives in accordance with established processes and guidelines.

What’s more, the fact that NASA is advertising the position is partly due to some recent changes to the role. As Catharine Conley*, NASA’s only planetary protection officer since 2014, indicated in a recent interview with Business Insider: “This new job ad is a result of relocating the position I currently hold to the Office of Safety and Mission Assurance, which is an independent technical authority within NASA.”

While the position has been undeniably important in the past, it is expected to become of even greater importance given NASA’s planned activities for the future. This includes NASA’s proposed “Journey to Mars“, a crewed mission which will see humans setting foot on the Red Planet sometime in the 2030s. And in just a few years time, the Mars 2020 rover is scheduled to begin searching the Martian surface for signs of life.

As part of this mission, the Mars 2020 rover will collect soil samples and place them in a cache to be retrieved by astronauts during the later crewed mission. Beyond Mars, NASA also hopes to conduct mission to Europa, Enceladus and Titan to look for signs of life. Each of these worlds have the necessary ingredients, which includes the prebiotic chemistry and geothermal energy necessary to support basic lifeforms.

Given that we intend to expand our horizons and explore increasingly exotic environments in the future – which could finally lead to the discovery of life beyond Earth – it only makes sense that the role of the Planetary Protection Officer become more prominent. If you think you’ve got the chops for it, and don’t mind a six-figure salary, be sure to apply soon!

*According to BI, Conley has not indicated if she will apply for the position again.

Further Reading: Business Insider, USAJOBS

August 2, 2017August 2, 2017 by Matt Williams

Kepler Spots the First Exomoon Candidate 4000 Light Years From Earth

Artist's impression of the view from a hypothetical moon around a exoplanet orbiting a triple star system. Credit: NASA

Ever since it was deployed in March of 2009, the Kepler mission has detected thousands of extra-solar planet candidates. In fact, between 2009 and 2012, it detected a total of 4,496 candidates, and confirmed the existence of 2,337 exoplanets. Even after two of its reaction wheels failed, the spacecraft still managed to turn up distant planets as part of its K2 mission, accounting for another 521 candidates and confirming 157.

However, according to a new study conducted by a pair of researches from Columbia University and a citizen scientist, Kepler may also have also found evidence of an extra-solar moon. After sifting through data from hundreds of transits detected by the Kepler mission, the researchers found one instance where a transiting planet showed signs of having a satellite.

Their study – which recently published online under the title “HEK VI: On the Dearth of Galilean Analogs in Kepler and the Exomoon Candidate Kepler-1625b I” – was by led Alex Teachey, a graduate student at Columbia University and a Graduate Research Fellow with the National Science Foundation (NSF). He was joined by David Kipping, an Assistant Professor of Astronomy at Columbia University and the Principal Investigator of The Hunt for Exomoons with Kepler (HEK) project, and Allan Schmitt, a citizen scientist.

*Artist’s impression of NASA’s Kepler spacecraft. Credit: NASA*

For years, Dr. Kipping has been searching the Kepler database for evidence of exomoons, as part of the HEK. This is not surprising, considering the kinds of opportunities that exomoons present for scientific research. Within our Solar System, the study of natural satellites has revealed important things about the mechanisms that drive early and late planet formation, and moons possess interesting geological features that are commonly found on other bodies.

It is for this reason that extending that research to the hunt for exoplanets is seen as necessary. Already, exoplanet-hunting missions like Kepler have turned up a wealth of planets that challenge conventional ideas about how planet formation and what kinds of planets are possible. The most noteworthy example are gas giants that have observed orbiting very close to their stars (aka. “Hot Jupiters”).

As such, the study of exomoons could yield valuable information about what kinds of satellites are possible, and whether or not our own moons are typical. As Teachey told Universe Today via email:

“Exomoons could tell us a lot about the formation of our Solar System, and other star systems. We see moons in our Solar System, but are they common elsewhere? We tend to think so, but we can’t know for sure until we actually see them. But it’s an important question because, if we find out there aren’t very many moons out there, it suggests maybe something unusual was going on in our Solar System in the early days, and that could have major implications for how life arose on the Earth. In other words, is the history of our Solar System common across the galaxy, or do we have a very unusual origin story? And what does that say about the chances of life arising here? Exomoons stand to offer us clues to answering these questions.”

*A montage of some of the potentially-habitable moons in our Solar System. From top to bottom, left to right, these include Europa, Enceladus, TItan and Ceres. Credit: NASA/JPL*

What’s more, many moons in the Solar System – including Europa, Ganymede, Enceladus and Titan – are thought to be potentially habitable. This is due to the fact that these bodies have steady supplies of volatiles (such as nitrogen, water, carbon dioxide, ammonia, hydrogen, methane and sulfur dioxide) and possess internal heating mechanisms that could provide the necessary energy to power biological processes.

Here too, the study of exomoons presents interesting possibilities, such as whether or not they may be habitable or even Earth-like. For these and other reasons, astronomers want to see if the planets that have been confirmed in distant star systems have systems of moons and what conditions are like on them. But as Teachey indicated, the search for exomoons presents a number of challenges compared to exoplanet-hunting:

“Moons are difficult to find because 1) we expect them to be quite small most of the time, meaning the transit signal will be quite weak to begin with, and 2) every time a planet transits, the moon will show up in a different place. This makes them more difficult to detect in the data, and modeling the transit events is significantly more computationally expensive. But our work leverages the moons showing up in different places by taking the time-averaged signal across many different transit events, and even across many different exoplanetary systems. If the moons are there, they will in effect carve out a signal on either side of the planetary transit over time. Then it’s a matter of modeling this signal and understanding what it means in terms of moon size and occurrence rate.”

To locate signs of exomoons, Teachey and his colleagues searched through the Kepler database and analyzed the transits of 284 exoplanet candidates in front of their respective stars. These planets ranged in size from being Earth-like to Jupiter-like in diameter, and orbited their stars at a distance of between ~0.1 to 1.0 AU. They then modeled the light curve of the stars using the techniques of phase-folding and stacking.

*An artist’s conception of a habitable exomoon. Credit: NASA*

These techniques are commonly used by astronomers who monitor stars for dips in luminosity that are caused by the transits of planets (i.e. the transit method). As Teachey explained, the process is quite similar:

“Basically we cut up the time-series data into equal pieces, each piece having one transit of the planet in the middle. And when we stack these pieces together we’re able to get a clearer picture of what the transit looks like… For the moon search we do essentially the same thing, only now we’re looking at the data outside the main planetary transit. Once we stack the data, we take the average values of all the data points within a certain time window and, if a moon is present, we ought to see some missing starlight there, which allows us to deduce its presence.”

What they found was a single candidate located in the Kepler-1625 system, a yellow star located about 4000 light years from Earth. Designated Kepler-1625B I, this moon orbits the large gas giant that is located within the star’s habitable zone, is 5.9 to 11.67 times the size of Earth, and orbits its star with a period of 287.4 days. This exomoon candidate, if it should be confirmed, will be the first exomoon ever discovered

The team’s results (which await peer review) also demonstrated that large moons to be a rare occurrence in the inner regions of star systems (within 1 AU). This was something of a surprise, though Teachey acknowledges that it is consistent with recent theoretical work. According to what some recent studies suggest, large planets like Jupiter could lose their moons as they migrate inward.

If this should prove to be the case, then what Teachey and his colleagues witnessed could be seen as evidence of that process. It could also be an indication our current exoplanet-hunting missions may not be up to the task of detecting exomoons. In the coming years, next-generations missions are expected to provide more detailed analyses of distant stars and their planetary systems.

*An artist’s conception of a distance exomoon blocking out a star’s light. Credit: Dan*

However, as Teachey indicated, these too could be limited in terms of what they can detect, and new strategies may ultimately be needed:

“The rarity of moons in the inner regions of these star systems suggests that individual moons will remain difficult to find in the Kepler data, and upcoming missions like TESS, which should find lots of very short period planets, will also have a difficult time finding these moons. It’s likely the moons, which we still expect to be out there somewhere, reside in the outer regions of these star systems, much as they do in our Solar System. But these regions are much more difficult to probe, so we will have to get even more clever about how we look for these worlds with present and near-future datasets.”

In the meantime, we can certainly be exited about the fact that the first exomoon appears to have been discovered. While these results await peer review, confirmation of this moon will mean additional research opportunities for Kepler-1625 system. The fact that this moon orbits within the star’s habitable zone is also an interesting feature, though its not likely the moon itself is habitable.

Still, the possibility of a habitable moon orbiting a gas giant is certainly interesting. Does that sound like something that might have come up in some science fiction movies?

Further Reading: arXiv

August 2, 2017 by David Dickinson

A Partial Lunar Eclipse Ushers in Eclipse Season

Live on the wrong continent to witness the August 21^st total solar eclipse? Well… celestial mechanics has a little consolation prize for Old World observers, with a partial lunar eclipse on the night of Monday into Tuesday, August 7/8^th.

A partial lunar eclipse occurs when the Moon just nicks the inner dark core of the Earth’s shadow, known as the umbra. This eclipse is centered on the Indian Ocean region, with the event occurring at moonrise for the United Kingdom, Europe and western Africa and moonset/sunrise for New Zealand and Japan. Western Australia, southern Asia and eastern Africa will see the entire eclipse.

The path of the Moon through the Earth’s shadow Monday night. Credit: adapted from NASA/GSFC/Fred Espenak

The penumbral phase of the eclipse begins on August 7^th at 15:50 Universal Time (UT), though you probably won’t notice a slight tea colored shading on the face of the Moon until about half an hour in. The partial phases begin at 17:23 UT, when the ragged edge of the umbra becomes apparent on the southeastern limb of the Moon. The deepest partial eclipse occurs at 18:22 UT with 25% of the Moon submerged in the umbra. Partial phase lasts 116 minutes in duration, and the entire eclipse is about five hours long.

The viewing prospects for the partial lunar eclipse. Credit: NASA/GSFC/Fred Espenak.

This also marks the start of the second and final eclipse season for 2017. Four eclipses occur this year: a penumbral lunar eclipse and annular solar eclipse this past February, and this month’s partial lunar and total solar eclipse.

Eclipses always occur in pairs, or very rarely triplets with an alternating lunar-solar pattern. This is because the tilt of the Moon’s orbit is inclined five degrees relative to the ecliptic, the plane of the Earth’s orbit around the Sun. The Moon therefore misses the 30′ wide disk of the Sun and the 80′ – 85′ wide inner shadow of the Earth on most passes.

Fun fact: at the Moon’s 240,000 mile distance from the Earth, the ratio of the apparent size of the Moon and the shadow is approximately equivalent to a basketball and a hoop.

When celestial bodies come into alignment, however, things can get interesting. For an eclipse to occur, the nodes – the point where the Moon’s orbit intersects the ecliptic – need to align with the position of the Moon and the Sun. There are two nodes, one descending with the Moon crossing the ecliptic from north to south, and one ascending. The time it takes for the Moon to return to the same node (27.2 days) is a draconitic month. Moreover, the nodes are moving around the Earth due to drag on the Moon’s orbit mainly by the Sun, and move all the way around the zodiac once every 18.6 years.

Got all that? Let’s put it into practice with this month’s eclipses. First, the Moon crosses its descending node at 10:56 UT on August 8th, just over 16 hours after Monday’s partial eclipse. Two weeks later, however, the Moon crosses ascending node just under eight hours from the central conjunction with the Sun, and a total solar eclipse occurs.

Tales of the Saros

The August 7^th lunar eclipse is member number 62 of the 83 lunar eclipses in saros series 119, which started on October 14^th, 935 AD and will end with a final shallow penumbral eclipse on March 25^th, 2396 AD. If you witnessed the lunar eclipse of July 28^th, 1999, then you saw the last lunar eclipse in the same saros. Saros 119 produced its last total lunar eclipse on June 15^th, 1927.

The next lunar eclipse, a total occurs on January 31^st, 2018, favoring the Pacific rim regions.

Partial lunar eclipses have occasionally work their way into history, usually as bad omens. One famous example is the partial lunar eclipse of May 22^nd, 1453 which preceded the Fall of Constantinople to the Ottoman Turks by a week. Apparently, a long standing legend claimed that a lunar eclipse would be the harbinger of the fall of Byzantium, and the partially eclipsed Moon rising over the besieged city ramparts seemed to fulfill the prophecy.

In our more enlightened age, we can simply enjoy Monday’s partial lunar eclipse as a fine celestial spectacle. You don’t need any special equipment to enjoy a lunar eclipse, just a view from the correct Moonward facing hemisphere of the Earth, and reasonably clear skies.

See the curve of the Earth’s shadow? This is one of the very few times that you can see that the Earth is indeed round (sorry, Flat Earthers) with your own eyes. And this curve is true for observers watching the Moon on the horizon, or high overhead near the zenith.

This month’s lunar eclipse occurs in the astronomical constellation of Capricornus. The Moon will also occult the +5^th magnitude star 29 Capricorni for southern India, Madagascar and South Africa shortly after the eclipse.

The viewing footprint for the 29 Capricorni occultation shortly after the eclipse. Credit: Occult 4.2.

Finally, anyone out there planning on carrying the partial lunar eclipse live, let us know… curiously, even Slooh seems to be sitting this one out.

Update: we have one possible broadcast, via Shahrin Ahmad (@shahgazer on Twitter). Updates to follow!

The final eclipse season for 2017 is now underway, starting Monday night. Nothing is more certain in this Universe than death, taxes and celestial mechanics, as the path of the Moon now sends it headlong to its August 21^st destiny and the Great American Total Solar Eclipse.

-We’ll be posting on Universe Today once more pre-total solar eclipse one week prior, with weather predictions, solar and sunspot activity and prospects for viewing the eclipse from Earth and space and more!

-Read more about this year’s eclipses in our 2017 Guide to 101 Astronomical Events.

-Eclipse… science fiction? Read our original eclipse-fueled tales Exeligmos, Shadowfall, Peak Season and more!

August 1, 2017August 1, 2017 by Matt Williams

Impending Asteroid Flyby Will be a Chance to Test NASA’s Planetary Defense Network!

Artist's concept of a large asteroid passing by the Earth-Moon system. Credit: A combination of ESO/NASA images courtesy of Jason Major/Lights in the Dark.

This coming October, an asteroid will fly by Earth. Known as 2012 TC4, this small rock is believed to measure between 10 and 30 meters (30 and 100 feet) in size. As with most asteroids, this one is expected to sail safely past Earth without incident. This will take place on October 12th, when the asteroid will pass us at a closest estimated distance of 6,800 kilometers (4,200 miles) from Earth’s surface.

That’s certainly good news. But beyond the fact that it does not pose a threat to Earth, NASA is also planning on using the occasion to test their new detection and tracking network. As part of their Planetary Defense Coordination Office (PDCO), this network is responsible for detecting and tracking asteroids that periodically pass close to Earth, which are known as Potentially Hazardous Objects (PHOs)

In addition to relying on data provided by NASA’s Near-Earth Object (NEO) Observations Program. the PDCO also coordinates NEO observations conducted by National Science Foundation (NSF)-sponsored ground-based observatories, as well as space situational awareness facilities run by the US Air Force. Aside from finding and tracking PHOs, the PDCO is also responsible for coming up with ways of deflecting and redirecting them.

*On Oct. 12, 2017, asteroid 2012 TC4 will safely fly past Earth at an estimated distance of 6,800 km (4,200 mi). Credits: NASA/JPL-Caltech*

The PDCO was officially created in response to the NASA Office of Inspector General’s 2014 report, titled “NASA’s Efforts to Identify Near-Earth Objects and Mitigate Hazards.” Citing such events as the Chelyabinsk meteor, and how such events are relatively common, the report indicated that coordination, early warning and mitigation strategies were needed for the future:

“[I]n February 2013 an 18-meter (59 foot) meteor exploded 14.5 miles above the city of Chelyabinsk, Russia, with the force of 30 atomic bombs, blowing out windows, destroying buildings, injuring more than 1,000 people, and raining down fragments along its trajectory… Recent research suggests that Chelyabinsk-type events occur every 30 to 40 years, with a greater likelihood of impact in the ocean than over populated areas, while impacts from objects greater than a mile in diameter are predicted only once every several hundred thousand years.”

The PDCO was established in 2016, which makes this upcoming flyby the first chance they will have to test their network of observatories and scientists dedicated to planetary defense. Michael Kelley is the program scientist and the NASA Headquarters lead for the TC4 observation campaign, which has been monitoring 2012 TC4 for years. As he said in a recent NASA press statement:

“Scientists have always appreciated knowing when an asteroid will make a close approach to and safely pass the Earth because they can make preparations to collect data to characterize and learn as much as possible about it. This time we are adding in another layer of effort, using this asteroid flyby to test the worldwide asteroid detection and tracking network, assessing our capability to work together in response to finding a potential real asteroid threat.”

*Diagram showing the data gathered from 1994-2013, indicating daytime (orange) and nighttime (blue) impacts of small meteorites. Credit: NASA*

In addition, the flyby will be an opportunity to reacquire 2012 TC4, which astronomers lost track of in 2012 when it moved beyond the range of their telescopes. For this reason, people like Professor Vishnu Reddy of the University of Arizona are also excited. A member of the Lunar and Planetary Laboratory, Reddy also leads the campaign to reacquire the asteroid. As he indicated, this flyby will be a chance for collaborative observation.

“This is a team effort that involves more than a dozen observatories, universities and labs across the globe so we can collectively learn the strengths and limitations of our near-Earth object observation capabilities,” he said. “This effort will exercise the entire system, to include the initial and follow-up observations, precise orbit determination, and international communications.”

2012 TC4 was originally discovered on Oct. 5th, 2012, by the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) at the Haleakala Observatory in Hawaii. After it sped past Earth in that same year, it has not been directly observed since. And while it is slightly larger than the meteor that exploded in Earth’s atmosphere near Chelyabinsk, Russia, in 2013, scientists are certain that it will pass us by at a safe distance.

This is based on tracking data that was collected by scientists from NASA’s Center for Near-Earth Object Studies (CNEOS). After monitoring 2012 TC4 for a period of seven days after it was discovered in 2012, they determined that at its closest approach, the asteroid will pass no closer than 6,800 km (4,200 mi) to Earth. However, it is more likely that it will pass us at distance of about 270,000 km (170,000 mi).

*The Pan-Starrs telescope at dawn. The mountain in the distance is Mauna Kea, about 130 kilometers southeast. Credit: pan-starrs.ifa.hawaii.edu*

This would place it at a distance that is about two-thirds the distance between the Earth and the Moon. The last time this asteroid passed Earth, it did so at a distance that was one-quarter the distance between the Earth and the Moon. Therefore, the odds of it passing by without incident are even greater this time around. So rather than representing a threat, the passage of this asteroid represents a good chance for research.

As Paul Chodas, the manager of the CNEOS at NASA’s Jet Propulsion Laboratory, stated:

“This is the perfect target for such an exercise because while we know the orbit of 2012 TC4 well enough to be absolutely certain it will not impact Earth, we haven’t established its exact path just yet. It will be incumbent upon the observatories to get a fix on the asteroid as it approaches, and work together to obtain follow-up observations than make more refined asteroid orbit determinations possible.”

By monitoring 2012 TC4 as it flies by, astronomers will be able to refine their knowledge about the asteroid’s orbit, which will help them to predict and calculate future flybys with even greater precision. This will further mitigate the risk posed by PHOs down the road, and help the PDCO to develop and test strategies to address possible future impacts.

In short, remain calm! This flyby is a good thing!

Further Reading: NASA

July 31, 2017July 31, 2017 by Matt Williams

NASA Detects More Chemicals on Titan that are Essential to Life

Titan's atmosphere makes Saturn's largest moon look like a fuzzy orange ball in this natural-color view from the Cassini spacecraft. Cassini captured this image in 2012. Image Credit: NASA/JPL-Caltech/Space Science Institute — According to a study from UCLA, Titan experiences severe methane rainstorms, leading to a the alluvial fans found found in both hemispheres. Credit: NASA/JPL-Caltech/Space Science Institute

Saturn’s largest moon Titan may be the most fascinating piece of real-estate in the Solar System right now. Not surprising, given the fact that the moon’s dense atmosphere, rich organic environment and prebiotic chemistry are thought to be similar to Earth’s primordial atmosphere. As such, scientists believe that the moon could act as a sort of laboratory for studying the processes whereby chemical elements become the building blocks for life.

These studies have already led to a wealth of information, which included the recent discovery of “carbon chain anions” – which are thought to be building blocks for more complex molecules. And now, thanks to data from the the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile, a team of NASA researchers have detected the presence of acrylonitrile, another chemical elements that could be the basis for life on that moon.

The study that details their findings – titled “ALMA detection and astrobiological potential of vinyl cyanide on Titan” – was published in the July 28th issue of the journal Science Advances. In it, the team explains how data from the ALMA array indicated that large quantities of acrylonitrile (C₂H₃CN) exist on Titan – most likely within the moon’s stratosphere.

As Maureen Palmer, a researcher with the Goddard Center for Astrobiology and the lead author on the paper, indicated in a NASA press release: “We found convincing evidence that acrylonitrile is present in Titan’s atmosphere, and we think a significant supply of this raw material reaches the surface.”

Also known as vinyl cyanide, acrylonitrile is used here on Earth in the manufacture of plastics. In the past, it has been speculated that this compound could be present in Titan’s atmosphere. However, it was only recently that scientists became aware of the possibility that it be the basis for living creatures within Titan’s rich organic environment – with its steady supply of carbon, hydrogen, and nitrogen.

This is based on a study that was conducted in 2015, where a team of Cornell scientists sought to determine if organic cells could form in Titan’s harsh environment. Given that the moon experiences average surface temperatures of -179 °C (-290 °F) and the atmosphere is predominantly nitrogen and hydrocarbons, lipid bilayer membranes (which are the foundation of life on Earth) could not survive there.

However, after conducting molecular simulations, the team determined that small organic nitrogen compounds would be capable of forming a sheet of material similar to a cell membrane. They also determined that these sheets could form hollow, microscopic spheres that they dubbed “azotosomes”, and that the best chemical candidate for this sheets would be acrylonitrile.

*Artist concept of Methane-Ethane lakes on Titan (Credit: Copyright 2008 Karl Kofoed). Click for larger version.*

Such a material would be capable of surviving in liquid methane and at extremely cold temperatures, and would therefore be the most likely basis for organic life on Titan. As Michael Mumma, the director of the Goddard Center for Astrobiology, explained:

“The ability to form a stable membrane to separate the internal environment from the external one is important because it provides a means to contain chemicals long enough to allow them to interact. If membrane-like structures could be formed by vinyl cyanide, it would be an important step on the pathway to life on Saturn’s moon Titan.”

For the sake of their study, the Goddard team combined 11 high-resolution data sets from ALMA, which they retrieved from an archive of observations that were used to calibrate the array. From the data, Palmer and her team determined that acrylonitrile is relatively abundant in Titan’s atmosphere, reaching concentrations of up to 2.8 parts per billion. They also determined that it would be most common in Titan’s upper atmosphere.

It is here that carbon, hydrogen and nitrogen could chemically bond from exposure to sunlight and energetic particles from Saturn’s magnetic field. Eventually, the acrylonitrile would make its way down through the cold atmosphere and condense to form rain droplets that would fall to the surface. The team also estimated how much of this material would accumulate in Ligeia Mare – Titan’s second-largest methane lake – over time.

Finally, they calculated that within every cubic centimeter (cm³) of its volume, Ligeia Mare could form as many as 10,000,000 azotosomes. That roughly ten times the amount of bacteria that exists in the waters along Earth’s coastal regions. As Martin Cordiner, one of the senior authors on the paper, indicated, these findings are certainly encouraging when it comes to the search for extra-terrestrial life in our Solar System.

“The detection of this elusive, astrobiologically relevant chemical is exciting for scientists who are eager to determine if life could develop on icy worlds such as Titan,” he said. “This finding adds an important piece to our understanding of the chemical complexity of the solar system.”

Granted, the study and the basis for its conclusions are quite speculative. But they do show that within certain established parameters, life could exist within our Solar System well-beyond the limits of our Sun’s “habitable zone”. This study could also have implications in the hunt for life in extrasolar systems. If scientists can say definitively that life does not need warmer temperatures and liquid water to exist, it opens up immense possibilities.

In the coming decades, several missions are expected to go to Titan, ranging from submarines that will explore its methane lakes to drones and aerial platforms that will study its atmosphere and surface. Already, it is expected that they will obtain valuable information about the formation of the Saturn system. But to also discover entirely new forms of life? That would truly be Earth-shattering!

Further Reading: NASA, Science Advances