The Last Survivors on Earth

The Last Survivors on Earth:

The world's most indestructible species, the tardigrade, an eight-legged micro-animal, also known as the water bear, will survive until the Sun dies, according to a new Oxford University collaboration. The new study published in Scientific Reports, has shown that the tiny creatures, will survive the risk of extinction from all astrophysical catastrophes, and be around for at least 10 billion years - far longer than the human race.

Although much attention has been given to the cataclysmic impact that an astrophysical event would have on human life, very little has been published around what it would take to kill the tardigrade, and wipe out life on this planet.

The research implies that life on Earth in general, will extend as long as the Sun keeps shining. It also reveals that once life emerges, it is surprisingly resilient and difficult to destroy, opening the possibility of life on other planets.

Tardigrades are the toughest, most resilient form of life on earth, able to survive for up to 30 years without food or water, and endure temperature extremes of up to 150 degrees Celsius, the deep sea and even the frozen vacuum of space. The water-dwelling micro animal can live for up to 60 years, and grow to a maximum size of 0.5mm, best seen under a microscope. Researchers from the Universities of Oxford and Harvard, have found that these life forms will likely survive all astrophysical calamities, such as an asteroid, since they will never be strong enough to boil off the world's oceans.

Three potential events were considered as part of their research, including; large asteroid impact, and exploding stars in the form of supernovae or gamma ray bursts.

There are only a dozen known asteroids and dwarf planets with enough mass to boil the oceans (2x10^18 kg), these include (Vesta 2x10^20 kg) and Pluto (10^22 kg), however none of these objects will intersect the Earth's orbit and pose a threat to tardigrades.

In order to boil the oceans an exploding star would need to be 0.14 light-years away. The closest star to the Sun is four light years away and the probability of a massive star exploding close enough to Earth to kill all forms of life on it, within the Sun's lifetime, is negligible.

Gamma-ray bursts are brighter and rarer than supernovae. Much like supernovas, gamma-ray bursts are too far away from earth to be considered a viable threat. To be able to boil the world's oceans the burst would need to be no more than 40 light-years away, and the likelihood of a burst occurring so close is again, minor.

Dr Rafael Alves Batista, Co-author and Post-Doctoral Research Associate in the Department of Physics at Oxford University, said: 'Without our technology protecting us, humans are a very sensitive species. Subtle changes in our environment impact us dramatically. There are many more resilient species' on earth. Life on this planet can continue long after humans are gone.

'Tardigrades are as close to indestructible as it gets on Earth, but it is possible that there are other resilient species examples elsewhere in the universe. In this context there is a real case for looking for life on Mars and in other areas of the solar system in general. If Tardigrades are earth's most resilient species, who knows what else is out there.'

Dr David Sloan, Co-author and Post-Doctoral Research Associate in the Department of Physics at Oxford University, said: 'A lot of previous work has focused on 'doomsday' scenarios on Earth - astrophysical events like supernovae that could wipe out the human race. Our study instead considered the hardiest species - the tardigrade. As we are now entering a stage of astronomy where we have seen exoplanets and are hoping to soon perform spectroscopy, looking for signatures of life, we should try to see just how fragile this hardiest life is. To our surprise we found that although nearby supernovae or large asteroid impacts would be catastrophic for people, tardigrades could be unaffected. Therefore it seems that life, once it gets going, is hard to wipe out entirely. Huge numbers of species, or even entire genera may become extinct, but life as a whole will go on.'

In highlighting the resilience of life in general, the research broadens the scope of life beyond Earth, within and outside of this solar system. Professor Abraham Loeb, co-author and chair of the Astronomy department at Harvard University, said: 'It is difficult to eliminate all forms of life from a habitable planet. The history of Mars indicates that it once had an atmosphere that could have supported life, albeit under extreme conditions. Organisms with similar tolerances to radiation and temperature as tardigrades could survive long-term below the surface in these conditions. The subsurface oceans that are believed to exist on Europa and Enceladus, would have conditions similar to the deep oceans of Earth where tardigrades are found, volcanic vents providing heat in an environment devoid of light. The discovery of extremophiles in such locations would be a significant step forward in bracketing the range of conditions for life to exist on planets around other stars.'

Credit: ox.ac.uk

More to Life Than the Habitable Zone

More to Life Than the Habitable Zone:

Two separate teams of scientists have identified major challenges for the development of life in what has recently become one of the most famous exoplanet systems, TRAPPIST-1. The teams, both led by researchers at the Harvard-Smithsonian Center for Astrophysics (CfA) in Cambridge, Mass., say the behavior of the star in the TRAPPIST-1 system makes it much less likely than generally thought, that planets there could support life.

The TRAPPIST-1 star, a red dwarf, is much fainter and less massive than the Sun. It is rapidly spinning and generates energetic flares of ultraviolet (UV) radiation.

The first team, a pair of CfA theorists, considered many factors that could affect conditions on the surfaces of planets orbiting red dwarfs. For the TRAPPIST-1 system they looked at how temperature could have an impact on ecology and evolution, plus whether ultraviolet radiation from the central star might erode atmospheres around the seven planets surrounding it. These planets are all much closer to the star than the Earth is to the Sun, and three of them are located well within the habitable zone.

"The concept of a habitable zone is based on planets being in orbits where liquid water could exist," said Manasvi Lingam, a Harvard researcher who led the study. "This is only one factor, however, in determining whether a planet is hospitable for life."

Lingam and his co-author, Harvard professor Avi Loeb, found that planets in the TRAPPIST-1 system would be barraged by UV radiation with an intensity far greater than experienced by Earth.

"Because of the onslaught by the star's radiation, our results suggest the atmosphere on planets in the TRAPPIST-1 system would largely be destroyed," said Loeb. "This would hurt the chances of life forming or persisting."

Lingam and Loeb estimate that the chance of complex life existing on any of the three TRAPPIST-1 planets in the habitable zone is less than 1% of that for life existing on Earth.

In a separate study, another research team from the CfA and the University of Massachusetts in Lowell found that the star in TRAPPIST-1 poses another threat to life on planets surrounding it. Like the Sun, the red dwarf in TRAPPIST-1 is sending a stream of particles outwards into space. However, the pressure applied by the wind from TRAPPIST-1's star on its planets is 1,000 to 100,000 times greater than what the solar wind exerts on the Earth.

The authors argue that the star’s magnetic field will connect to the magnetic fields of any planets in orbit around it, allowing particles from the star’s wind to directly flow onto the planet’s atmosphere. If this flow of particles is strong enough, it could strip the planet's atmosphere and perhaps evaporate it entirely.

"The Earth's magnetic field acts like a shield against the potentially damaging effects of the solar wind," said Cecilia Garraffo of the CfA, who led the new study. "If Earth were much closer to the Sun and subjected to the onslaught of particles like the TRAPPIST-1 star delivers, our planetary shield would fail pretty quickly."

While these two studies suggest that the likelihood of life may be lower than previously thought, it does not mean the TRAPPIST-1 system or others with red dwarf stars are devoid of life.

"We're definitely not saying people should give up searching for life around red dwarf stars," said Garraffo's co-author Jeremy Drake, also from CfA. "But our work and the work of our colleagues shows we should also target as many stars as possible that are more like the Sun."

The paper by Lingam and Loeb was published in the International Journal of Astrobiology and is available online. The paper by Garraffo et al, also available online, has been published by The Astrophysical Journal Letters.

Headquartered in Cambridge, Mass., the Harvard-Smithsonian Center for Astrophysics (CfA) is a joint collaboration between the Smithsonian Astrophysical Observatory and the Harvard College Observatory. CfA scientists, organized into six research divisions, study the origin, evolution and ultimate fate of the universe.

Credit: cfa.harvard.edu

New Horizons Unveils New Maps of Pluto, Charon on Flyby Anniversary

New Horizons Unveils New Maps of Pluto, Charon on Flyby Anniversary:

On July 14, 2015, NASA's New Horizons spacecraft made its historic flight through the Pluto system – providing the first close-up images of Pluto and its moons and collecting other data that has transformed our understanding of these mysterious worlds on the solar system's outer frontier. Scientists are still analyzing and uncovering data that New Horizons recorded and sent home after the encounter. On the two-year anniversary of the flyby, the team is unveiling a set of detailed, high-quality global maps of Pluto and its largest moon, Charon.

"The complexity of the Pluto system — from its geology to its satellite system to its atmosphere— has been beyond our wildest imagination," said Alan Stern, New Horizons principal investigator from the Southwest Research Institute in Boulder, Colorado. "Everywhere we turn are new mysteries. These new maps from the landmark exploration of Pluto by NASA's New Horizons mission in 2015 will help unravel these mysteries and are for everyone to enjoy."

The new maps include global mosaics of Pluto and Charon, assembled from nearly all of the highest-resolution images obtained by New Horizons' Long-Range Reconnaissance Imager (LORRI) and the Multispectral Visible Imaging Camera (MVIC). These mosaics are the most detailed and comprehensive global views yet of the Pluto and Charon surfaces using New Horizons data.

The new collection also includes topography maps of the hemispheres of Pluto and Charon visible to New Horizons during the spacecraft's closest approach. The topography is derived from digital stereo-image mapping tools that measure the parallax – or the difference in the apparent relative positions – of features on the surface obtained at different viewing angles during the encounter. Scientists use these parallax displacements of high and low terrain to estimate landform heights.

Both the new Pluto and the new Charon global mosaics have been overlain with transparent, colorized topography data wherever on their surfaces stereo data is available.

The Johns Hopkins University Applied Physics Laboratory, Laurel, Maryland, manages the New Horizons mission for NASA's Science Mission Directorate. Stern, of the Southwest Research Institute (SwRI), is the principal investigator and leads the mission; SwRI leads the science team, payload operations, and encounter science planning. New Horizons is part of the New Frontiers Program managed by NASA's Marshall Space Flight Center in Huntsville, Alabama. APL designed, built and operates the New Horizons spacecraft.

Credit: pluto.jhuapl.edu

AIDA Mission to Validate Crucial Asteroid Deflection Technology

AIDA Mission to Validate Crucial Asteroid Deflection Technology:

While there is currently no imminent asteroid threat and none of known near-Earth objects (NEOs) is on collision course with our planet, humanity should be prepared for the worst. With that thought in mind NASA and ESA are developing the Asteroid Impact and Deflection Assessment (AIDA) mission, which main goal is to demonstrate the kinetic impact technique that could change the motion of a potentially hazardous asteroid.

The AIDA mission will consist of two spacecraft sent to the binary asteroid called Didymos. Built by ESA, the Asteroid Impact Mission (AIM) will be launched in October 2020 and is expected to be injected into the orbit of the larger asteroid. NASA’s contribution to this endeavor, the Double Asteroid Redirection Test (DART), will be launched into space nearly one year later and slated to crash into the smaller asteroid in October 2022. AIM will be just in place to observe the impact and study its aftermath.

“This mission, in partnership with ESA and NASA, will allow us to validate the technology of the kinetic impactor and also to improve our understanding of threatening asteroids,” Patrick Michel, AIM/AIDA investigator at the Côte d'Azur Observatory (OCA), told Astrowatch.net.

Therefore, the mission would be essential for the most one of the most important asteroid deflection technology – the kinetic impactor. In particular, AIDA will demonstrate the feasibility of this technique based on the data gathered by observing DART’s crash into the Didymos’ moon with a velocity of about six km/s. AIM will orbit the asteroid in order to perform detailed before-and-after observations of the structure of the space rock itself, as well as its orbit, to thoroughly characterize the kinetic impact and the consequences.

“To make sure a technique is valid and that we know how to use it, we need a test. Otherwise, we can talk but it will remain on paper and we cannot guarantee anything. And this is why we still push for the AIDA space mission to happen,” Michel said.

He noted that the success of AIDA will have many implications for planetary defense, science and asteroid mining because the knowledge needed for these three aims is essentially the same. According to him, it will prove that asteroids are the only natural risk that we can predict and prevent by making the necessary steps.

“AIDA, if done, will accomplish the step that will allow us to tell the future generations: we did our duty, we have now a validated tool to prevent the risk! And it will also come with science and technology returns, which contributes to inspire young generations,” Michel noted.

The AIM spacecraft is still in its conceptual phase. When it comes to DART, the probe was recently moved by NASA from concept development to preliminary design phase.

A New Search for Extrasolar Planets from the Arecibo Observatory

A New Search for Extrasolar Planets from the Arecibo Observatory:

The National Science Foundation’s Arecibo Observatory and the Planetary Habitability Laboratory of the University of Puerto Rico at Arecibo joined the Red Dots project using the ESO’s exoplanet-hunter in the search for new planets around our nearest stars. This new collaboration will simultaneously observe in both the optical and radio spectrum Barnard’s Star, a popular star in the science fiction literature.

Barnard's star is a low-mass red dwarf almost six light-years away and the second-closest stellar system to our Sun after the Alpha Centauri triple-star system. There are hints of a possible super-Earth mass planet in a cold orbit around this star. 

The Arecibo Observatory has a new campaign to observe nearby red dwarf stars with planets. The purpose of this campaign is to detect radio emissions from these stars, such as from flares, to help characterize their radiation and magnetic environment and any potential perturbations due to other bodies. These perturbations might reveal the presence of new sub-stellar objects including planets.

Barnard’s Star will be the eighth red dwarf star to be recently observed by the Arecibo Observatory. Results from Gliese 436, Ross 128, Wolf 359, HD 95735, BD +202465, V* RY Sex, and K2-18 are currently being analyzed. These observations are led by Prof. Abel Méndez, Director of the Planetary Habitability Laboratory of the University of Puerto Rico at Arecibo in collaboration with Dr. Jorge Zuluaga from the Universidad de Antioquia in Colombia.

The Red Dots team will be joining the observations with the Arecibo Observatory of Barnard’s Star in coordination with other observatories. They are planning simultaneous photometric and spectral observations from SNO, LCO, TJO, and CARMENES from Spain, and earlier with ASH2 from Chile. All these observations will be used to understand the star but more observations using the ESO’s exoplanet-hunter by the Red Dots team will be necessary for the detection and confirmation of any new planet.

The first extrasolar planets were discovered from the Arecibo Observatory in 1992. They were three small planets named Draugr, Poltergeist, and Phobetor around the Lich Pulsar, a fast rotating neutron star that emits a beam of electromagnetic radiation. The first planet around a sun-like star was later discovered in 1995 and today we know of more than 3,500 of them. Recent observations by the Arecibo Observatory have been able to detect brown dwarfs, but no new planet yet.

The first and only time that Barnard’s Star was observed from the Arecibo Observatory was during the SETI Institute’s Phoenix Project (1998-2004). The new observations are in a different frequency (4 to 5 GHz) where radio emission from stellar flares have been observed in other similar or cooler objects. This is the first time Barnard’s Star is seen with such frequencies and sensitivity.

The observations of Barnard’s Star will take place on Sunday, July 16. Another star, Ross 128, will be observed again later that day because it showed potential radio emissions that require follow-up. Results from these observations will be available later that week. The Red Dots team keeps an open journal of their observational campaign.

Credit: phl.upr.edu

Planets Like Earth May Have Had Muddy Origins

Planets Like Earth May Have Had Muddy Origins:

Scientists have long held the belief that planets – including Earth – were built from rocky asteroids, but new research challenges that view. Published in Science Advances, a journal of the American Association for the Advancement of Science, the research suggests that many of the original planetary building blocks in our solar system may actually have started life, not as rocky asteroids, but as gigantic balls of warm mud.

Phil Bland, Curtin University planetary scientist, undertook the research to try and get a better insight into how smaller planets, the precursors to the larger terrestrial planets we know today, may have come about. 

Planetary Science Institute Senior Scientist Bryan Travis is a co-author on the paper “Giant convecting mud balls of the early Solar System” that appears in Science Advances. 

“The assumption has been that hydrothermal alteration was occurring in certain classes of rocky asteroids with material properties similar to meteorites,” Travis said. “However, these bodies would have accreted as a high-porosity aggregate of igneous clasts and fine-grained primordial dust, with ice filling much of the pore space. Mud would have formed when the ice melted from heat released from decay of radioactive isotopes, and the resulting water mixed with fine-grained dust.” 

Travis used his Mars and Asteroids Global Hydrology Numerical Model (MAGHNUM) to carry out computer simulations, adapting MAGHNUM to be able to simulate movement of a distribution of rock grain sizes and flow of mud in carbonaceous chondrite asteroids. 

The results showed that many of the first asteroids, those that delivered water and organic material to the terrestrial planets, may have started out as giant convecting mud balls and not as consolidated rock. 

The findings could provide a new scientific approach for further research into the evolution of water and organic material in our solar system, and generate new approaches to how and where we continue our search for other habitable planets. 

Credit: psi.edu

Gamma-ray Telescopes Reveal a High-energy Trap in Our Galaxy's Center

Gamma-ray Telescopes Reveal a High-energy Trap in Our Galaxy's Center:

A combined analysis of data from NASA's Fermi Gamma-ray Space Telescope and the High Energy Stereoscopic System (H.E.S.S.), a ground-based observatory in Namibia, suggests the center of our Milky Way contains a "trap" that concentrates some of the highest-energy cosmic rays, among the fastest particles in the galaxy.

"Our results suggest that most of the cosmic rays populating the innermost region of our galaxy, and especially the most energetic ones, are produced in active regions beyond the galactic center and later slowed there through interactions with gas clouds," said lead author Daniele Gaggero at the University of Amsterdam. "Those interactions produce much of the gamma-ray emission observed by Fermi and H.E.S.S." 

Cosmic rays are high-energy particles moving through space at almost the speed of light. About 90 percent are protons, with electrons and the nuclei of various atoms making up the rest. In their journey across the galaxy, these electrically charged particles are affected by magnetic fields, which alter their paths and make it impossible to know where they originated.

But astronomers can learn about these cosmic rays when they interact with matter and emit gamma rays, the highest-energy form of light.

In March 2016, scientists with the H.E.S.S. Collaboration reported gamma-ray evidence of the extreme activity in the galactic center. The team found a diffuse glow of gamma rays reaching nearly 50 trillion electron volts (TeV). That's some 50 times greater than the gamma-ray energies observed by Fermi's Large Area Telescope (LAT). To put these numbers in perspective, the energy of visible light ranges from about 2 to 3 electron volts.

The Fermi spacecraft detects gamma rays when they enter the LAT. On the ground, H.E.S.S. detects the emission when the atmosphere absorbs gamma rays, which triggers a cascade of particles resulting in a flash of blue light. 

In a new analysis, published July 17 in the journal Physical Review Letters, an international team of scientists combined low-energy LAT data with high-energy H.E.S.S. observations. The result was a continuous gamma-ray spectrum describing the galactic center emission across a thousandfold span of energy.

"Once we subtracted bright point sources, we found good agreement between the LAT and H.E.S.S. data, which was somewhat surprising due to the different energy windows and observing techniques used," said co-author Marco Taoso at the Institute of Theoretical Physics in Madrid and Italy's National Institute of Nuclear Physics (INFN) in Turin.

This agreement indicates that the same population of cosmic rays — mostly protons — found throughout the rest of the galaxy is responsible for gamma rays observed from the galactic center. But the highest-energy share of these particles, those reaching 1,000 TeV, move through the region less efficiently than they do everywhere else in the galaxy. This results in a gamma-ray glow extending to the highest energies H.E.S.S. observed.

"The most energetic cosmic rays spend more time in the central part of the galaxy than previously thought, so they make a stronger impression in gamma rays," said co-author Alfredo Urbano at the European Organization for Nuclear Research (CERN) in Geneva and INFN Trieste.

This effect is not included in conventional models of how cosmic rays move through the galaxy. But the researchers show that simulations incorporating this change display even better agreement with Fermi data.

"The same breakneck particle collisions responsible for producing these gamma rays should also produce neutrinos, the fastest, lightest and least understood fundamental particles," said co-author Antonio Marinelli of INFN Pisa. Neutrinos travel straight to us from their sources because they barely interact with other matter and because they carry no electrical charge, so magnetic fields don't sway them.

"Experiments like IceCube in Antarctica are detecting high-energy neutrinos from beyond our solar system, but pinpointing their sources is much more difficult," said Regina Caputo, a Fermi team member at NASA's Goddard Space Flight Center in Greenbelt, Maryland, who was not involved in the study. "The findings from Fermi and H.E.S.S. suggest the galactic center could be detected as a strong neutrino source in the near future, and that's very exciting."

The Fermi mission is an astrophysics and particle physics partnership, developed by NASA in collaboration with the U.S. Department of Energy, along with important contributions from academic institutions and partners in France, Germany, Italy, Japan, Sweden and the United States. The H.E.S.S. Collaboration includes scientists from Germany, France, the United Kingdom, Poland, the Czech Republic, Ireland, Armenia, South Africa and Namibia.

Credit: NASA

New Hot Jupiter Marks the First Collaborative Exoplanet Discovery

New Hot Jupiter Marks the First Collaborative Exoplanet Discovery:

Researchers led by a team at Keele University have discovered a new ‘Hot Jupiter’ exoplanet. The new giant planet was jointly discovered by a WASP/KELT survey collaboration, marking the first time an exoplanet has been discovered between two planet search groups.

The exoplanet, WASP-167b/KELT-13b, is several times more massive than Jupiter and orbits its parent star every two days. Its host star, WASP-176/KELT-13, is one of the hottest and most rapidly rotating stars known to host such a planet.

The Wide Angle Search for Planets (WASP) and the Kilodegree Extremely Little Telescope (KELT) exoplanet surveys observed the host star between 2006 and 2013 using the WASP-South telescope and the KELT-South telescope at the South African Astronomical Observatory (SAAO). A follow-up observation in 2016 at the European South Observatory (ESO) confirmed the presence of the exoplanet.

The astronomy teams were led by Lorna Temple, Astrophysics Researcher at Keele University, who explained:

“Planet-search teams are only just beginning to find hot-Jupiter planets with hot, fast-rotating host stars. This is only the second of what I hope will be many WASP planets that fall into this category. Already we are seeing characteristic properties that contrast those we’ve seen before, and I’m looking forward to filling in this emerging big picture with more new discoveries.”

Lorna continued:

“This is the first planet discovery where two teams have collaborated, pooling all of the data to produce the best possible characterization of the system.”

Credit: keele.ac.uk

Ancient, Massive Asteroid Impact Could Explain Martian Geological Mysteries

Ancient, Massive Asteroid Impact Could Explain Martian Geological Mysteries:

The origin and nature of Mars are mysterious. The planet has geologically distinct hemispheres with smooth lowlands in the north and cratered, high-elevation terrain in the south. The red planet also has two small oddly-shaped oblong moons and a composition that sets it apart from that of the Earth.

New research by CU Boulder professor Stephen Mojzsis outlines a likely cause for these mysterious features of Mars: a colossal impact with a large asteroid early in the planet’s history. This asteroid—about the size of Ceres, one of the largest asteroids in the solar system—smashed into Mars, ripped off a chunk of the northern hemisphere and left behind a legacy of metallic elements in the planet’s interior. The crash also created a ring of rocky debris around Mars that may have later clumped together to form its moons, Phobos and Deimos.

The study appeared online in the journal Geophysical Research Letters, a publication of the American Geophysical Union, in June. 

“We showed in this paper—that from dynamics and from geochemistry—that we could explain these three unique features of Mars,” said Mojzsis, a professor in CU Boulder’s Department of Geological Sciences. “This solution is elegant, in the sense that it solves three interesting and outstanding problems about how Mars came to be.”

Astronomers have long wondered about these features. Over 30 years ago, scientists proposed a large asteroid impact to explain the disparate elevations of Mars’ northern and southern hemispheres; the theory became known as the “single impact hypothesis.” Other scientists have suggested that erosion, plate tectonics or ancient oceans could have sculpted the distinct landscapes. Support for the single impact hypothesis has grown in recent years, supported by computer simulations of giant impacts.

Mojzsis thought that by studying Mars’ metallic element inventory, he might be able to better understand its mysteries. He teamed up with Ramon Brasser, an astronomer at the Earth-Life Science Institute at the Tokyo Institute of Technology in Japan, to dig in.

The team studied samples from Martian meteorites and realized that an overabundance of rare metals—such as platinum, osmium and iridium—in the planet’s mantle required an explanation. Such elements are normally captured in the metallic cores of rocky worlds, and their existence hinted that Mars had been pelted by asteroids throughout its early history. By modeling how a large object such as an asteroid would have left behind such elements, Mojzsis and Brasser explored the likelihood that a colossal impact could account for this metal inventory.

The two scientists first estimated the amount of these elements from Martian meteorites, and deduced that the metals account for about 0.8 percent of Mars’ mass. Then, they used impact simulations with different-sized asteroids striking Mars to see which size asteroid accumulated the metals at the rate they expected in the early solar system.

Based on their analysis, Mars’ metals are best explained by a massive meteorite collision about 4.43 billion years ago, followed by a long history of smaller impacts. In their computer simulations, an impact by an asteroid at least 1,200 kilometers (745 miles) across was needed to deposit enough of the elements. An impact of this size also could have wildly changed the crust of Mars, creating its distinctive hemispheres.

In fact, Mojzsis said, the crust of the northern hemisphere appears to be somewhat younger than the ancient southern highlands, which would agree with their findings.

“The surprising part is how well it fit into our understanding of the dynamics of planet formation,” said Mojzsis, referring to the theoretical impact. “Such a large impact event elegantly fits in to what we understand from that formative time.”

Such an impact would also be expected to have generated a ring of material around Mars that later coalesced into Phobos and Deimos; this explains in part why those moons are made of a mix of native and non-Martian material. 

In the future, Mojzsis will use CU Boulder’s collection of Martian meteorites to further understand Mars’ mineralogy and what it can tell us about a possible asteroid impact. Such an impact should have initially created patchy clumps of asteroid material and native Martian rock. Over time, the two material reservoirs became mixed. By looking at meteorites of different ages, Mojzsis can see if there’s further evidence for this mixing pattern and, therefore, potentially provide further support for a primordial collision.

“Good theories make predictions,” said Mojzsis, referring to how the impact theory may predict how Mars’ makeup. By studying meteorites from Mars and linking them with planet-formation models, he hopes to better our understanding of how massive, ancient asteroids radically changed the red planet in its earliest days.

Credit: colorado.edu

Scientists Reveal New Connections Between Small Particles and the Vast Universe

Scientists Reveal New Connections Between Small Particles and the Vast Universe:

Our observable universe is the largest object that physicists study: It spans a diameter of almost 100 billion light years. The density correlations in our universe, for example, correlations between numbers of galaxies at different parts of the universe, indicate that our vast universe has originated from a stage of cosmic inflation.

On the other hand, elementary particles are the smallest object that physicists study. A particle physics Standard Model (SM) was established 50 years ago, describing all known particles and their interactions.

Are density distributions of the vast universe and the nature of smallest particles related? In a recent research, scientists from the Hong Kong University of Science and Technology (HKUST) and Harvard University revealed the connection between those two aspects, and argued that our universe could be used as a particle physics "collider" to study the high energy particle physics. Their findings mark the first step of cosmological collider phenomenology and pave the way for future discovery of new physics unknown yet to mankind.

The research was published in the journal Physical Review Letters on June 29, 2017 (doi:10.1103/PhysRevLett.118.261302) and the preprint is available online (https://arxiv.org/abs/1610.06597).

"Ongoing observations of cosmological microwave background and large scale structures have achieved impressive precision, from which valuable information about primordial density perturbations can be extracted, " said Yi Wang, a co-author of the paper and an assistant professor at HKUST's department of physics. "A careful study of this SM background would be the prerequisite for using the cosmological collider to explore any new physics, and any observational signal that deviates from this background would then be a sign of physics beyond the SM."

The team carried out a two-step task to work out the background of the SM model. The first step was to work out the SM spectrum during inflation, which turned out to be dramatically different from that obtained from the particle physics calculation in flat space. The second one was to figure out how the SM fields entered the cosmological density correlation functions.

"Just like the line pattern of the light you see when observing a mercury lamp through a spectrometer, the mass distribution of the fundamental particles in SM also presents a special pattern, or a 'mass spectrum', which can be viewed as the fingerprint of SM," explained Zhong-Zhi Xianyu, a co-author and physicist at Center for Mathematical Sciences and Applications in Harvard University, "However, this fingerprint is subject to change if we change the ambient conditions. Just like the light spectrum changes when applying strong magnetic field to the lamp, the spectrum of the SM particles turns out to be very different at the time of inflation from it is now due to the inflationary background." The team carefully examined all effects from inflation and showed how the mass spectrum of SM would look like for different inflation models.

"Through inflation, the spectrum of elementary particles is encoded in the statistics of the distribution of the contents of the universe, such as the galaxies and cosmic microwave background, that we observe today", explains Xingang Chen, a co-author and scientist in the Harvard-Smithsonian Center for Astrophysics. "This is the connection between the smallest and largest."

Many problems along this direction remain to be explored. "In our minimal setup, the Standard Model particles interact with the inflaton (the driving force of inflation) rather weakly. But if some new particles can mediate stronger interactions between these two sectors, we would expect to observe a stronger signal of new physics," said Wang. "The cosmological collider is an ideal arena for new physics beyond SM."

Credit: eurekalert.org

Hubble Sees Phobos Orbiting the Red Planet

Hubble Sees Phobos Orbiting the Red Planet:

The sharp eye of NASA's Hubble Space Telescope has captured the tiny moon Phobos during its orbital trek around Mars. Because the moon is so small, it appears star-like in the Hubble pictures. Over the course of 22 minutes, Hubble took 13 separate exposures, allowing astronomers to create a time-lapse video showing the diminutive moon's orbital path. The Hubble observations were intended to photograph Mars, and the moon's cameo appearance was a bonus.

A football-shaped object just 16.5 miles by 13.5 miles by 11 miles, Phobos is one of the smallest moons in the solar system. It is so tiny that it would fit comfortably inside the Washington, D.C. Beltway.

The little moon completes an orbit in just 7 hours and 39 minutes, which is faster than Mars rotates. Rising in the Martian west, it runs three laps around the Red Planet in the course of one Martian day, which is about 24 hours and 40 minutes. It is the only natural satellite in the solar system that circles its planet in a time shorter than the parent planet's day.

About two weeks after the Apollo 11 manned lunar landing on July 20, 1969, NASA's Mariner 7 flew by the Red Planet and took the first crude close-up snapshot of Phobos. On July 20, 1976 NASA's Viking 1 lander touched down on the Martian surface. A year later, its parent craft, the Viking 1 orbiter, took the first detailed photograph of Phobos, revealing a gaping crater from an impact that nearly shattered the moon.

​Phobos was discovered by Asaph Hall on August 17, 1877 at the U.S. Naval Observatory in Washington, D.C., six days after he found the smaller, outer moon, named Deimos. Hall was deliberately searching for Martian moons.

Both moons are named after the sons of Ares, the Greek god of war, who was known as Mars in Roman mythology. Phobos (panic or fear) and Deimos (terror or dread) accompanied their father into battle.

Close-up photos from Mars-orbiting spacecraft reveal that Phobos is apparently being torn apart by the gravitational pull of Mars. The moon is marred by long, shallow grooves that are probably caused by tidal interactions with its parent planet. Phobos draws nearer to Mars by about 6.5 feet every hundred years. Scientists predict that within 30 to 50 million years, it either will crash into the Red Planet or be torn to pieces and scattered as a ring around Mars.

Orbiting 3,700 miles above the Martian surface, Phobos is closer to its parent planet than any other moon in the solar system. Despite its proximity, observers on Mars would see Phobos at just one-third the width of the full moon as seen from Earth. Conversely, someone standing on Phobos would see Mars dominating the horizon, enveloping a quarter of the sky.

From the surface of Mars, Phobos can be seen eclipsing the sun. However, it is so tiny that it doesn't completely cover our host star. Transits of Phobos across the sun have been photographed by several Mars-faring spacecraft.

The origin of Phobos and Deimos is still being debated. Scientists concluded that the two moons were made of the same material as asteroids. This composition and their irregular shapes led some astrophysicists to theorize that the Martian moons came from the asteroid belt.

However, because of their stable, nearly circular orbits, other scientists doubt that the moons were born as asteroids. Such orbits are rare for captured objects, which tend to move erratically. An atmosphere could have slowed down Phobos and Deimos and settled them into their current orbits, but the Martian atmosphere is too thin to have circularized the orbits. Also, the moons are not as dense as members of the asteroid belt.

Phobos may be a pile of rubble that is held together by a thin crust. It may have formed as dust and rocks encircling Mars were drawn together by gravity. Or, it may have experienced a more violent birth, where a large body smashing into Mars flung pieces skyward, and those pieces were brought together by gravity. Perhaps an existing moon was destroyed, reduced to the rubble that would become Phobos.

Hubble took the images of Phobos orbiting the Red Planet on May 12, 2016, when Mars was 50 million miles from Earth. This was just a few days before the planet passed closer to Earth in its orbit than it had in the past 11 years.

The Hubble Space Telescope is a project of international cooperation between NASA and ESA (European Space Agency). NASA's Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore, Maryland, conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, Inc., in Washington, D.C.

Credit: NASA

Asteroid 2017 BS5 to Pass by Earth on Sunday

Asteroid 2017 BS5 to Pass by Earth on Sunday:

An asteroid discovered in January is about to give Earth a close shave on Sunday, July 23. The object, designated 2017 BS5, will pass by our planet at 19:17 UTC at a safe distance of approximately 3.1 lunar distances (LD), or 1.19 million kilometers.

2017 BS5 was first observed on January 25, 2017 using the Asteroid Terrestrial-Impact Last Alert System (ATLAS) at Haleakala Observatory, Hawaii. It is an astronomical survey system for detection of dangerous asteroids a few weeks to days before their close approaches to Earth.

According to astronomers, 2017 BS5 is an Amor-type asteroid with an absolute magnitude of 24.1 and an estimated diameter between 28 and 90 meters. The object has a semimajor axis of about 1.0 AU and it takes it one year to fully orbit the sun. On Sunday, it will fly by our planet with a relative velocity of 5.8 km/s.

In the coming years 2017 BS5 will make close approaches to Earth twice a year. The next fly-by of this asteroid is expected to take place on January 17, 2018 when it will pass by our planet at a distance of approximately 41 LD.

Currently, there are 1,803 potentially hazardous asteroids (PHAs) detected to date. PHAs are space rocks larger than approximately 100 meters that can come closer to Earth than 19.5 LD. However, none of the known PHAs is on a collision course with our planet.

Ground-Breaking Ground-Based Images of Planets Obtained by Pic-Net Pro-Am Team

Ground-Breaking Ground-Based Images of Planets Obtained by Pic-Net Pro-Am Team:

The first observing run of a collaboration between amateur and professional astronomers to monitor our planetary neighbors has resulted in some of the best planetary images ever taken from the ground. The ‘Pic-Net’ project aims to use the one-meter diameter planetary telescope at the Pic du Midi Observatory in the French Pyrenees to monitor the meteorology of planets in our Solar System, measure global winds in their atmospheres, monitor impact of minor planet bodies producing giant fireballs in planetary atmospheres, and provide observational support for various space missions.

Last month, a small team of amateur astronomers carried out a pilot observing run during a workshop funded by the Europlanet 2020 Research Infrastructure (RI). Superb-quality images of Jupiter, Saturn, Venus and Jupiter’s moon Ganymede were obtained during four nights of observations, as well as images of Uranus and Neptune.

“The key to the success of this project is our highly-experienced team of observers, the optical quality of the telescope, the highly stable atmosphere at the Pic du Midi observatory and cutting-edge instrumentation,” said Francois Colas, astronomer at the Institut de Mécanique Céleste et de Calcul des Ephémérides (IMCCE) and telescope and instrumentation lead of the Pic-Net project. “We believe that these are some of the best planetary observations from the ground to date.”

Repeated observations with ground-based telescopes provide a long-term, global view of planets that can put the detailed, close-up data collected by orbiting space missions into context. Amateur astronomers with relatively small telescopes can make extremely valuable scientific contributions by observing at dates where no equivalent data is available. Several observing runs like those from the Pic-Net pilot are needed over a year to understand the changes in the atmospheres of planets.

“Images obtained through Pic-Net can provide important, ongoing support for space missions,” said Marc Delcroix, an amateur astronomer who has piloted the use of the one-meter diameter telescope and is the organizer of the Europlanet workshop. “For instance, the high quality of Pic-Net observations of Saturn, which show clearly the hexagon feature surrounding the north polar vortex, atmospheric bands and cloud features, will also provide an avenue for continued study of Saturn and build on the legacy of the Cassini mission, which ends in September.”

Over the last 15 years, amateur astronomers have proven their skills, experience and potential in planetary imaging using new fast cameras that ‘freeze’ optical distortions introduced by the atmosphere on high-resolution telescopic observations. Professional astronomers collaborate closely with amateurs in many areas of planetary sciences, including the study of the atmospheres of planets like Venus, Jupiter or Saturn.

The ultimate goal of the Pic-Net project is to provide experienced observers with more access to the Pic-Midi facility in order to extract the full potential of the telescope and the observing site over time. Regular visits with an enlarged team of observers are envisioned as part of the Pic-Net project.

“The Pic-Net program provides invaluable support for the Juno mission and complements other Earth-based observations from professional astronomers,” noted Glenn Orton of Jet Propulsion Laboratory, California Institute of Technology, who is the Juno science team member in charge of coordinating Earth-based observations to extend and enhance the science return from Juno’s investigation of Jupiter and its magnetosphere.

Orton added, “These observations not only provide details on planetary cloud morphology that are close to what we might expect from the Hubble Space Telescope, but also such a program of regular observing allows us to understand the evolution of intermediate- to small-sized features on a variety of time scales, helping Juno scientists to understand the history of features for which the spacecraft only gets one or two ‘snapshots’ on each close approach.”

Javier Peralta, team member of JAXA’s Akatsuki mission commented, “In the case of Venus, the amateur observations have experienced incredible steps forward in the last years. Images in ultraviolet and near-infrared wavelengths permit the study of winds at two altitudes of the dayside clouds, even when Venus is close to being at its furthest point from Earth, while smart combinations of infrared filters for nightside observations now allow us to clearly resolve many surface elevations. These are much needed in support of the Akatsuki mission.”

Credit: europlanet-eu.org

Spiral Arms Allow School Children to Weigh Black Holes

Spiral Arms Allow School Children to Weigh Black Holes:

Astronomers from Swinburne University of Technology, Australia, and the University of Minnesota Duluth, USA, have provided a way for armchair astronomers, and even primary school children, to merely look at a spiral galaxy and estimate the mass of its hidden, central black hole. The research was supported by the Australian Research Council and has been published in the journal Monthly Notices of the Royal Astronomical Society​.

Given that black holes emit no discernible light, they have traditionally been studied via highly technical observations of the stars and gas orbiting around them, which in turn provide a measurement of how massive they must be.

Now, new research based on these pre-existing measurements has shown that a black hole’s mass can be accurately estimated by simply looking at the spiral arms of its host galaxy.

Nearly a century ago, Sir James Jeans and Edwin Hubble noted how spiral galaxies with large central bulges possess tightly wound spiral arms, while spiral galaxies with small bulges display wide open spiral arms. Since then, hundreds of thousands, if not millions, of spiral galaxies have been classified as type Sa, Sb, Sc, Sd, depending on their spiral arms.

Prof Marc Seigar, Associate Dean of the Swenson College of Science and Engineering at the University of Minnesota Duluth, and co-author of the study, discovered a relationship between central black hole mass and the tightness of a galaxy’s spiral arms nearly a decade ago.

Dr Benjamin Davis and Prof Alister Graham, from Swinburne’s Centre for Astrophysics and Supercomputing, led the new research revising this connection between black hole mass and spiral arm geometry.

After carefully analyzing a larger sample of galaxies, imaged by an array of space telescopes, the researchers observed an unexpectedly strong relationship, and one which predicts lower mass black holes in galaxies with open spiral arms (types Sc and Sd).

“The strength of the correlation is competitive with, if not better than, all our other methods used to predict black hole masses,” says Dr Davis. “Anyone can now look at an image of a spiral galaxy and immediately gauge how massive its black hole should be.”

Given that it is the discs of galaxies that host the spiral pattern, the study highlights the poorly-known connection between galaxy discs and black holes. Moreover, the procedure allows for the prediction of black hole masses in pure disc galaxies with no stellar bulge. “This implies that black holes and the discs of their host galaxies must co-evolve,” says Dr Davis.

"It's now as easy as 'a,b,c' to unlock this mystery of our Universe and reveal the black hole masses in spiral galaxies,” says Prof Graham.

“Importantly, the relation will also help searches for the suspected, but currently missing, population of intermediate-mass black holes with masses between 100 and 100,000 times the mass of our Sun. Difficult to pin down, they have masses greater than that of any single star, but are smaller than the supermassive black holes which grow to billions of times the mass of our Sun in giant galaxies,” Prof Graham says.

Working within the Australian Research Council’s OzGrav Centre for Excellence, the astronomers intend to hunt down these elusive black holes, and investigate implications for the production of gravitational waves: those ripples in the fabric of Einstein’s space-time that were first announced by the LIGO and Virgo collaborations in 2016.

Credit: ras.org.uk

Scientists Get Best Measure of Star-forming Material in Galaxy Clusters in Early Universe

Scientists Get Best Measure of Star-forming Material in Galaxy Clusters in Early Universe:

The international Spitzer Adaptation of the Red-sequence Cluster Survey (SpARCS) collaboration based at the University of California, Riverside has combined observations from several of the world’s most powerful telescopes to carry out one of the largest studies yet of molecular gas – the raw material which fuels star formation throughout the universe – in three of the most distant clusters of galaxies ever found, detected as they appeared when the universe was only four billion years old.

Results were recently published in The Astrophysical Journal Letters. Allison Noble, a postdoctoral researcher at the Massachusetts Institute of Technology, led this newest research from the SpARCS collaboration.

Clusters are rare regions of the universe consisting of tight groups of hundreds of galaxies containing trillions of stars, as well as hot gas and mysterious dark matter. First, the research team used spectroscopic observations from the W. M. Keck Observatory on Mauna Kea, Hawai’i, and the Very Large Telescope in Chile that confirmed 11 galaxies were star-forming members of the three massive clusters. Next, the researchers took images through multiple filters from NASA’s Hubble Space Telescope, which revealed a surprising diversity in the galaxies’ appearance, with some galaxies having already formed large disks with spiral arms.

One of the telescopes the SpARCS scientists used is the extremely sensitive Atacama Large Millimeter Array (ALMA) telescope capable of directly detecting radio waves emitted from the molecular gas found in galaxies in the early universe. ALMA observations allowed the scientists to determine the amount of molecular gas in each galaxy, and provided the best measurement yet of how much fuel was available to form stars.

The researchers compared the properties of galaxies in these clusters with the properties of “field galaxies” (galaxies found in more typical environments with fewer close neighbors). To their surprise, they discovered that cluster galaxies had higher amounts of molecular gas relative to the amount of stars in the galaxy, compared to field galaxies. The finding puzzled the team because it has long been known that when a galaxy falls into a cluster, interactions with other cluster galaxies and hot gas accelerate the shut off of its star formation relative to that of a similar field galaxy (the process is known as environmental quenching).

“This is definitely an intriguing result,” said Gillian Wilson, a professor of physics and astronomy at UC Riverside and the leader of the SpARCS collaboration. “If cluster galaxies have more fuel available to them, you might expect them to be forming more stars than field galaxies, and yet they are not.”

Noble, a SpARCS collaborator and the study’s leader, suggests several possible explanations: It is possible that something about being in the hot, harsh cluster environment surrounded by many neighboring galaxies perturbs the molecular gas in cluster galaxies such that a smaller fraction of that gas actively forms stars. Alternatively, it is possible that an environmental process, such as increased merging activity in cluster galaxies, results in the observed differences between the cluster and field galaxy populations.

“While the current study does not answer the question of which physical process is primarily responsible for causing the higher amounts of molecular gas, it provides the most accurate measurement yet of how much molecular gas exists in galaxies in clusters in the early universe,” Wilson said.

The SpARCS team has developed new techniques using infrared observations from NASA’s Spitzer Space Telescope to identify hundreds of previously undiscovered clusters of galaxies in the early universe. In the future, they plan to study a larger sample of clusters. The team has recently been awarded additional time on ALMA, the W. M. Keck Observatory, and the Hubble Space Telescope to continue investigating how the neighborhood in which a galaxy lives determines for how long it can form stars.

Credit: ucr.edu