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Can sound help us detect ‘earthquakes’ on Venus?

Seismic waves radiating from a Venus quake propagate as Rayleigh waves in the Venus surface layers and generate infrasonic waves traveling upwards through the dense Venus atmosphere. These low frequency sound waves can be detected by a balloon (upper left) floating within the Venus clouds at an altitude of 55 km where temperatures are similar to those on the Earth's surface. As the infrasonic waves penetrate the clouds and enter the upper atmosphere they produce thermal variations and molecular excitations. These signals can be viewed from space by infrared imaging sensors as an expanding pattern of concentric circles by on the orbiting spacecraft (upper right). Credit: Keck Institute for Space Studies (KISS)

Seismic waves radiating from a Venus quake propagate as Rayleigh waves in the Venus surface layers and generate infrasonic waves traveling upwards through the dense Venus atmosphere. These low frequency sound waves can be detected by a balloon (upper left) floating within the Venus clouds at an altitude of 55 km where temperatures are similar to those on the Earth’s surface. As the infrasonic waves penetrate the clouds and enter the upper atmosphere they produce thermal variations and molecular excitations. These signals can be viewed from space by infrared imaging sensors as an expanding pattern of concentric circles by on the orbiting spacecraft (upper right). Credit: Keck Institute for Space Studies (KISS)

Detecting an “earthquake” on Venus would seem to be an impossible task. The planet’s surface is a hostile zone of crushing pressure and scorching temperatures–about 874 degrees F, hot enough to melt lead–that would destroy any of the normal instruments used to gauge seismic activity.

But conditions in Venus’ atmosphere are much more hospitable, and it is here that researchers hope to deploy an array of balloons or satellites that could detect Venusian seismic activity–using sound.

These kinds of low frequency or infrasonic sound waves, much lower than an audible voice, are already measured on Earth. The rumbling or “hum” can be generated by sources as diverse as volcanoes, earthquakes, ocean storms and meteor air blasts.

In recent years, says Los Alamos National Laboratory researcher Stephen Arrowsmith, infrasonic observations have undergone a renaissance of sorts, especially as a relatively inexpensive way to monitor atmospheric nuclear weapons tests. But last year, a team of experts convened by the Keck Institute for Space Studies began thinking of ways to use infrasonic observations to get a better look at the geological dynamics of Venus.

At about 50-60 kilometers above Venus’ surface, the temperature and pressure conditions are much more like those on Earth, albeit with a denser atmosphere. This dense atmosphere helps translate any seismic waves into infrasonic waves that can be detected with instruments floating above the planet’s surface, says Jim Cutts, a Jet Propulsion Laboratory researcher who participated in the Keck conference. Infrasonic waves can be “felt” as either fluctuations in pressure, or as light emissions called airglow, or electron disruptions in Venus’ upper atmosphere.

Arrowsmith and colleagues say that barometric pressure changes might be detected with a series of balloons in the Venus cloud layer at 55 kilometers above the surface, such as those launched by the Soviet Union in Venus’ atmosphere in the 1980s.

In a second talk, Philippe Lognonné and colleagues discuss a complementary way to analyze the planet’s infrasonic waves, using orbiting satellites to detect airglow. In both cases, the first goal will be determine what the noise-to-signal ratio might be for these two techniques. The researchers want to know if the instruments onboard a balloon or satellite will be sensitive enough to detect and identify a seismic signal in the midst of other infrasonic waves, and how large of a seismic event might be detected by these observations.

If these techniques can help scientists get a better sense of seismic activity on the planet, it could tell them more about the history and current state of Venus’ interior, the researchers say. Venus’ inner evolution would be especially interesting to compare with Earth’s, to discover more about the diversity of planet formation and why certain features–such as tectonic plates and a dynamo mechanism in the core–exist on Earth but not on Venus.

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Tau Ceti: The next Earth? Probably not

How would an alien world like this look? That’s the question that undergraduate art major Joshua Gonzalez attempted to answer. He worked with Professor Patrick Young’s group to learn how to analyze stellar spectra to find chemical abundances, and inspired by the scientific results, he created two digital paintings of possible unusual extrasolar planets, one being Tau Ceti for his Barrett Honors Thesis. Credit: Joshua Gonzalez

How would an alien world like this look? That’s the question that undergraduate art major Joshua Gonzalez attempted to answer. He worked with Professor Patrick Young’s group to learn how to analyze stellar spectra to find chemical abundances, and inspired by the scientific results, he created two digital paintings of possible unusual extrasolar planets, one being Tau Ceti for his Barrett Honors Thesis. Credit: Joshua Gonzalez

As the search continues for Earth-size planets orbiting at just the right distance from their star, a region termed the habitable zone, the number of potentially life-supporting planets grows. In two decades we have progressed from having no extrasolar planets to having too many to search.

Narrowing the list of hopefuls requires looking at extrasolar planets in a new way. Applying a nuanced approach that couples astronomy and geophysics, Arizona State University researchers report that from that long list we can cross off cosmic neighbor Tau Ceti.

The Tau Ceti system, popularized in several fictional works, including Star Trek, has long been used in science fiction, and even popular news, as a very likely place to have life due to its proximity to Earth and the star’s sun-like characteristics. Since December 2012 Tau Ceti has become even more appealing, thanks to evidence of possibly five planets orbiting it, with two of these – Tau Ceti e and f – potentially residing in the habitable zone.

Using the chemical composition of Tau Ceti, the ASU team modeled the star’s evolution and calculated its habitable zone. Although their data confirms that two planets (e and f) may be in the habitable zone it doesn’t mean life flourishes or even exists there.

“Planet e is in the habitable zone only if we make very generous assumptions. Planet f initially looks more promising, but modeling the evolution of the star makes it seem probable that it has only moved into the habitable zone recently as Tau Ceti has gotten more luminous over the course of its life,” explains astrophysicist Michael Pagano, ASU postdoctoral researcher and lead author of the paper appearing in the Astrophysical Journal. The collaboration also included ASU astrophysicists Patrick Young and Amanda Truitt and mineral physicist Sang-Heon (Dan) Shim.

Based upon the team’s models, planet f has likely been in the habitable zone much less than 1 billion years. This sounds like a long time, but it took Earth’s biosphere about 2 billion years to produce potentially detectable changes in its atmosphere. A planet that entered the habitable zone only a few hundred million years ago may well be habitable and even inhabited, but not have detectable biosignatures.

According to Pagano, he and his collaborators didn’t pick Tau Ceti “hoping, wanting, or thinking” it would be a good candidate to look for life, but for the idea that these might be truly alien new worlds.

Tau Ceti has a highly unusual composition with respect to its ratio of magnesium and silicon, which are two of the most important rock forming minerals on Earth. The ratio of magnesium to silicon in Tau Ceti is 1.78, which is about 70% more than our sun.

The astrophysicists looked at the data and asked, “What does this mean for the planets?”

Building on the strengths of ASU’s School of Earth and Space Exploration, which unites earth and space scientists in an effort to tackle research questions through a holistic approach, Shim was brought on board for his mineral expertise to provide insights into the possible nature of the planets themselves.

“With such a high magnesium and silicon ratio it is possible that the mineralogical make-up of planets around Tau Ceti could be significantly different from that of Earth. Tau Ceti’s planets could very well be dominated by the mineral olivine at shallow parts of the mantle and have lower mantles dominated by ferropericlase,” explains Shim.

Considering that ferropericlase is much less viscous, or resistant to flowing, hot, yet solid, mantle rock would flow more easily, possibly having profound effects on volcanism and tectonics at the planetary surface, processes which have a significant impact on the habitability of Earth.

“This is a reminder that geological processes are fundamental in understanding the habitability of planets,” Shim adds.

“Tau Ceti has been a popular destination for science fiction writers and everyone’s imagination as somewhere there could possibly be life, but even though life around Tau Ceti may be unlikely, it should not be seen as a letdown, but should invigorate our minds to consider what exotic planets likely orbit the star, and the new and unusual planets that may exist in this vast universe,” says Pagano.

This work was supported by funding from the NASA Astrobiology Institute and NASA Nexus for Exoplanet System Science.

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Titan’s Atmosphere Useful In Study Of Hazy Exoplanets

Sunset on Saturn's moon Titan reveals the atmosphere around the moon as seen from the night side with NASA's Cassini spacecraft. Credit: NASA/JPL-Caltech/SSI

Sunset on Saturn’s moon Titan reveals the atmosphere around the moon as seen from the night side with NASA’s Cassini spacecraft.
Credit: NASA/JPL-Caltech/SSI

With more than a thousand confirmed planets outside of our solar system, astronomers are attempting to identify the atmospheres of these distant bodies to determine if they could possibly host life.

Yet, viewing a body so far away remains a challenge. Astronomers are honing their technique in exoplanet observation with an object we know much more about in our own solar system — Saturn’s moon, Titan. The process should help scientists better understand what a signal from a hazy planet that is similar to Titan would look like.

One of the problems with reading signals from the atmosphere on other planets is the difficulty in sorting out the differences between a thick cloud of smog-like haze from pockets of gas. At the same time, observers must contend with what astronomers call noise, extraneous signals not related to the planet they are studying. Whether it comes from material the light encounters along the way from the planet to Earth or from mechanical issues with the instruments, noise serves as static that may blur the actual readings.

“Observers struggle with trying to distinguish haze signals from gas signals from noise,” Tyler Robinson, of NASA Ames Research Center, told Astrobiology Magazine by email.

Robinson served as lead author on a study that used NASA’s Cassini spacecraft to examine Titan in a new way. His results were published in the journal Proceedings of the National Academy of Sciences and presented at the winter meeting of the American Astronomical Society in Seattle, Washington.

“We’ve provided an almost noise-free dataset to help exoplanet observers better interpret their observations.”

A haze-dominated ‘planet’

As a distant planet passes in front of its star, light passes through the atmosphere. By studying that passage with a variety of wavelengths using a method known as transit spectroscopy, scientists can see how the signal changes with each observation and determine the composition of the atmosphere.

Some planets have returned featureless readings, with no signs indicating atmospheric composition. To scientists, this suggests a high layer of clouds, or haze, in the atmosphere that absorbs the light from the star, blocking readings of the lower atmosphere that can tell scientists more about the planet’s atmosphere and its potential habitability.

An artist's concept of the 'hot Jupiter' Hat-P-7b. The Hubble Space Telescope studied the planet's atmospheric structure. Credit: NASA/ESA/G. Bacon, STScI

An artist’s concept of the ‘hot Jupiter’ Hat-P-7b. The Hubble Space Telescope studied the planet’s atmospheric structure. Credit: NASA/ESA/G. Bacon, STScI

“There is no problem detecting high-altitude cloud layers in the atmospheres of exoplanets — in fact they’re usually quite obvious,” Heather Knutson of the California Institute of Technology told Astrobiology Magazine.

Knutson, who was not involved in the research, studies the physics and chemistry of exoplanet atmospheres.

“The real problem is that these cloud layers are hiding the atmospheric absorption signals we are trying to measure. In some cases, high-altitude clouds can make a small planet with a puffy, hydrogen-rich atmosphere look like it has a much more compact atmosphere made of heavier gasses, such as water or carbon dioxide.”

To understand how high-altitude hazes can affect the passage of light through the atmosphere, Robinson and his team used the spacecraft Cassini-Huygens to study Saturn’s moon, Titan. Using Cassini, they observed the Sun rising and setting through the moon’s atmosphere, a process known as occultation. For this setup, the spacecraft is located fairly close to the moon, while the source of light—the Sun—was relatively far away. For exoplanet studies, the situation is reversed. The host star is relatively close to the planet, while observers on Earth are far away from the system.

“Occultations in the Solar System and in the transits of exoplanets are perfectly complementary,” Robinson said. “In both cases, the light that is transmitted through the atmosphere carries with it the spectral signatures of whatever gases, hazes, and clouds might be present in the planet’s atmosphere.”

Saturn’s moon Titan makes a perfect target for understanding hazy worlds. The satellite is the haziest body in the Solar System, with a nitrogen-rich upper atmosphere and clouds of methane that rain down on the surface of the planet.

An artist's concept of a Neptune-size planet with a clear atmosphere shown crossing in front of its star. Credit: NASA/JPL-Caltech

An artist’s concept of a Neptune-size planet with a clear atmosphere shown crossing in front of its star. Credit: NASA/JPL-Caltech

“Although other Solar System bodies have photochemical hazes, Titan is a great example of a body whose observable atmosphere is dominated by hazes,” Knutson said. “It’s also a nice object to study because it has a solid surface and a relatively thin atmosphere, and therefore might be a good analogue for a terrestrial exoplanet with a photochemical haze layer.”

The team found that the haze did a better job of blocking out blue light than red, rather than blocking all light equally as hazes were assumed to do. This means that exoplanets which were assumed to have Titan-like hazes but returned flat, featureless spectra actually have atmospheres dissimilar to that of Saturn’s moon.

“For the worlds where our current best explanation for their flat spectra is a planet-wide haze layer, though, our observations show that Titan’s haze isn’t a good analogy for whatever makes up the haze on these distant worlds,” Robinson said.

“Some other kind of haze, with different properties for interacting with light, could explain the flat spectrum.”

Another look

The Solar System is filled with many types of worlds, and scientists have used them in the past to attempt to understand exoplanets. Frequently, however, they have done so by modeling the planets from a great distance, so that it appears only as a small point of light. This method models how more exoplanets may be studied in the future, using a method known as direct imaging. Although most exoplanets today are studied using transit spectroscopy, no one had previously observed the transit spectra of Solar System objects as points of comparison.Titan may be the best solar system example of a hazy body, but other worlds can offer insight into the variety of exoplanets scientists are likely to discover.

“Most Solar System worlds have clouds or hazes of some types in their atmosphere,” Robinson said. “By studying occultations—by, say, Venus or Saturn’s atmosphere—in the Solar System, we have an exciting opportunity to explore the variety of ways hazes and clouds can sculpt transit spectra.”

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First Exoplanet Visible Light Spectrum

Artist’s impression of the exoplanet 51 Pegasi b. Credit: ESO/M. Kornmesser/Nick Risinger

Artist’s impression of the exoplanet 51 Pegasi b. Credit: ESO/M. Kornmesser/Nick Risinger

Astronomers using the HARPS planet-hunting machine at ESO’s La Silla Observatory in Chile have made the first-ever direct detection of the spectrum of visible light reflected off an exoplanet.

These observations also revealed new properties of this famous object, the first exoplanet ever discovered around a normal star: 51 Pegasi b. The result promises an exciting future for this technique, particularly with the advent of next generation instruments, such as ESPRESSO, on the VLT, and future telescopes, such as the E-ELT.

The exoplanet 51 Pegasi b lies some 50 light-years from Earth in the constellation of Pegasus. It was discovered in 1995 and will forever be remembered as the first confirmed exoplanet to be found orbiting an ordinary star like the Sun. It is also regarded as the archetypal hot Jupiter — a class of planets now known to be relatively commonplace, which are similar in size and mass to Jupiter, but orbit much closer to their parent stars.

Since that landmark discovery, more than 1900 exoplanets in 1200 planetary systems have been confirmed, but, in the year of the twentieth anniversary of its discovery, 51 Pegasi b returns to the ring once more to provide another advance in exoplanet studies.

The star 51 Pegasi in the constellation of Pegasus. Credit: ESO, IAU and Sky & Telescope

The star 51 Pegasi in the constellation of Pegasus. Credit: ESO, IAU and Sky & Telescope

The team that made this new detection was led by Jorge Martins from the Instituto de Astrofísica e Ciências do Espaço (IA)and the Universidade do Porto, Portugal, who is currently a PhD student at ESO in Chile. They used the HARPS instrument on the ESO 3.6-metre telescope at the La Silla Observatory in Chile.

Currently, the most widely used method to examine an exoplanet’s atmosphere is to observe the host star’s spectrum as it is filtered through the planet’s atmosphere during transit — a technique known as transmission spectroscopy. An alternative approach is to observe the system when the star passes in front of the planet, which primarily provides information about the exoplanet’s temperature.

The new technique does not depend on finding a planetary transit, and so can potentially be used to study many more exoplanets. It allows the planetary spectrum to be directly detected in visible light, which means that different characteristics of the planet that are inaccessible to other techniques can be inferred.

The host star’s spectrum is used as a template to guide a search for a similar signature of light that is expected to be reflected off the planet as it describes its orbit. This is an exceedingly difficult task as planets are incredibly dim in comparison to their dazzling parent stars.

The signal from the planet is also easily swamped by other tiny effects and sources of noise. In the face of such adversity, the success of the technique when applied to the HARPS data collected on 51 Pegasi b provides an extremely valuable proof of concept.

Jorge Martins explains: “This type of detection technique is of great scientific importance, as it allows us to measure the planet’s real mass and orbital inclination, which is essential to more fully understand the system. It also allows us to estimate the planet’s reflectivity, or albedo, which can be used to infer the composition of both the planet’s surface and atmosphere.”

Wide-field view of the sky around the star 51 Pegasi. Credit: ESO/Digitized Sky Survey 2

Wide-field view of the sky around the star 51 Pegasi. Credit: ESO/Digitized Sky Survey 2

51 Pegasi b was found to have a mass about half that of Jupiter’s and an orbit with an inclination of about nine degrees to the direction to the Earth. The planet also seems to be larger than Jupiter in diameter and to be highly reflective. These are typical properties for a hot Jupiter that is very close to its parent star and exposed to intense starlight.

HARPS was essential to the team’s work, but the fact that the result was obtained using the ESO 3.6-metre telescope, which has a limited range of application with this technique, is exciting news for astronomers. Existing equipment like this will be surpassed by much more advanced instruments on larger telescopes, such as ESO’s Very Large Telescope and the future European Extremely Large Telescope.

“We are now eagerly awaiting first light of the ESPRESSO spectrograph on the VLT so that we can do more detailed studies of this and other planetary systems,” concludes Nuno Santos, of the IA and Universidade do Porto, who is a co-author of the new paper.

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NASA’s NExSS Coalition to Lead Search for Life on Distant Worlds

The search for life beyond our solar system requires unprecedented cooperation across scientific disciplines. NASA's NExSS collaboration includes those who study Earth as a life-bearing planet (lower right), those researching the diversity of solar system planets (left), and those on the new frontier, discovering worlds orbiting other stars in the galaxy (upper right). Credits: NASA

The search for life beyond our solar system requires unprecedented cooperation across scientific disciplines. NASA’s NExSS collaboration includes those who study Earth as a life-bearing planet (lower right), those researching the diversity of solar system planets (left), and those on the new frontier, discovering worlds orbiting other stars in the galaxy (upper right). Credits: NASA

NASA is bringing together experts spanning a variety of scientific fields for an unprecedented initiative dedicated to the search for life on planets outside our solar system.

The Nexus for Exoplanet System Science, or “NExSS”, hopes to better understand the various components of an exoplanet, as well as how the planet stars and neighbor planets interact to support life.

“This interdisciplinary endeavor connects top research teams and provides a synthesized approach in the search for planets with the greatest potential for signs of life,” says Jim Green, NASA’s Director of Planetary Science. “The hunt for exoplanets is not only a priority for astronomers, it’s of keen interest to planetary and climate scientists as well.”

The study of exoplanets – planets around other stars – is a relatively new field. The discovery of the first exoplanet around a star like our sun was made in 1995. Since the launch of NASA’s Kepler space telescope six years ago, more than 1,000 exoplanets have been found, with thousands of additional candidates waiting to be confirmed. Scientists are developing ways to confirm the habitability of these worlds and search for biosignatures, or signs of life.

The key to this effort is understanding how biology interacts with the atmosphere, geology, oceans, and interior of a planet, and how these interactions are affected by the host star. This “system science” approach will help scientists better understand how to look for life on exoplanets.

NExSS will tap into the collective expertise from each of the science communities supported by NASA’s Science Mission Directorate:

  • Earth scientists develop a systems science approach by studying our home planet.
  • Planetary scientists apply systems science to a wide variety of worlds within our solar system.
  • Heliophysicists add another layer to this systems science approach, looking in detail at how the Sun interacts with orbiting planets.
  • Astrophysicists provide data on the exoplanets and host stars for the application of this systems science framework.

 

NExSS will bring together these prominent research communities in an unprecedented collaboration, to share their perspectives, research results, and approaches in the pursuit of one of humanity’s deepest questions: Are we alone?

The team will help classify the diversity of worlds being discovered, understand the potential habitability of these worlds, and develop tools and technologies needed in the search for life beyond Earth.

Dr. Paul Hertz, Director of the Astrophysics Division at NASA notes, “NExSS scientists will not only apply a systems science approach to existing exoplanet data, their work will provide a foundation for interpreting observations of exoplanets from future exoplanet missions such as TESS, JWST, and WFIRST.” The Transiting Exoplanet Survey Satellite (TESS) is working toward a 2017 launch, with the James Webb Space Telescope (JWST) scheduled for launch in 2018. The Wide-field Infrared Survey Telescope is currently being studied by NASA for a launch in the 2020’s.

NExSS will be led by Natalie Batalha of NASA’s Ames Research Center, Dawn Gelino with NExScI, the NASA Exoplanet Science Institute, and Anthony del Genio of NASA’s Goddard Institute for Space Studies. The NExSS project will also include team members from 10 different universities and two research institutes. These teams were selected from proposals submitted across NASA’s Science Mission Directorate.

The Berkeley/Stanford University team is led by James Graham. This “Exoplanets Unveiled” group will focus on this question: “What are the properties of exoplanetary systems, particularly as they relate to their formation, evolution, and potential to harbor life?”

Daniel Apai leads the “Earths in Other Solar Systems” team from the University of Arizona. The EOS team will combine astronomical observations of exoplanets and forming planetary systems with powerful computer simulations and cutting-edge microscopic studies of meteorites from the early solar system to understand how Earth-like planets form and how biocritical ingredients  — C, H, N, O-containing molecules — are delivered to these worlds.

http://otherearths.org

The Arizona State University team will take a similar approach. Led by Steven Desch, this research group will place planetary habitability in a chemical context, with the goal of producing a “periodic table of planets”. Additionally, the outputs from this team will be critical inputs to other teams modeling the atmospheres of other worlds.

Researchers from Hampton University will be exploring the sources and sinks for volatiles on habitable worlds. The “Living, Breathing Planet Team,” led by William B. Moore, will study how the loss of hydrogen and other atmospheric compounds to space has profoundly changed the chemistry and surface conditions of planets in the solar system and beyond. This research will help determine the past and present habitability of Mars and even Venus, and will form the basis for identifying habitable and eventually living planets around other stars.

http://sol.hamptonu.edu/project/the-living-breathing-planet/

The team centered at NASA’s Goddard Institute for Space Studies will investigate habitability on a more local scale. Led by Tony Del Genio, it will examine the habitability of solar system rocky planets through time, and will use that foundation to inform the detection and characterization of habitable exoplanets in the future.

http://www.giss.nasa.gov/projects/astrobio/

The NASA Astrobiology Institute’s Virtual Planetary Laboratory, based at the University of Washington, was founded in 2001 and is a heritage team of the NExSS network. This research group, led by Dr. Victoria Meadows, will combine expertise from Earth observations, Earth system science, planetary science, and astronomy to explore factors likely to affect the habitability of exoplanets, as well as the remote detectability of global signs of habitability and life.

Five additional teams were chosen from the Planetary Science Division portion of the Exoplanets Research Program (ExRP).  Each brings a unique combination of expertise to understand the fundamental origins of exoplanetary systems, through laboratory, observational, and modeling studies.

A group led by Neal Turner at NASA’s Jet Propulsion Laboratory, California Institute of Technology, will work to understand why so many exoplanets orbit close to their stars. Were they born where we find them, or did they form farther out and spiral inward? The team will investigate how the gas and dust close to young stars interact with planets, using computer modeling to go beyond what can be imaged with today’s telescopes on the ground and in space.

A team at the University of Wyoming, headed by Hannah Jang-Condell, will explore the evolution of planet formation, modeling disks around young stars that are in the process of forming their planets. Of particular interest are “transitional” disks, which are protostellar disks that appear to have inner holes or regions partially cleared of gas and dust. These inner holes may be caused in part by planets inside or near the holes.

A Penn State University team, led by Eric Ford, will strive to further understand planetary formation by investigating the bulk properties of small transiting planets and implications for their formation.

A second Penn State group, with Jason Wright as principal investigator, will study the atmospheres of giant planets that are transiting hot Jupiters with a novel, high-precision technique called diffuser-assisted photometry. This research aims to enable more detailed characterization of the temperatures, pressures, composition, and variability of exoplanet atmospheres.

http://science.psu.edu/news-and-events/2015-news/FordWright4-2015

The University of Maryland and NASA’s Goddard Space Flight Center team, with Wade Henning at the helm, will study tidal dynamics and orbital evolution of terrestrial class exoplanets. This effort will explore how intense tidal heating, such as the temporary creation of magma oceans, can actually save Earth-sized planets from being ejected during the orbital chaos of early solar systems.

Another University of Maryland project, led by Drake Deming, will leverage a statistical analysis of Kepler data to extract the maximum amount of information concerning the atmospheres of Kepler’s planets.

The group led by Hiroshi Imanaka from the SETI Institute will be conducting laboratory investigation of plausible photochemical haze particles in hot, exoplanetary atmospheres.

The Yale University team, headed by Debra Fischer, will design new spectrometers with the stability to reach Earth-detecting precision for nearby stars. The team will also make improvements to Planet Hunters, www.planethunters.org, a web interface that allows citizen scientists to search for transiting planets in the NASA Kepler public archive data. Citizen scientists have found more than 100 planets not previously detected; many of these planets are in the habitable zones of host stars.

A group led by Adam Jensen at the University of Nebraska-Kearney will explore the existence and evolution of exospheres around exoplanets, the outer, ‘unbound’ portion of a planet’s atmosphere. This team previously made the first visible light detection of hydrogen absorption from an exoplanet’s exosphere, indicating a source of hot, excited hydrogen around the planet. The existence of such hydrogen can potentially tell us about the long-term evolution of a planet’s atmosphere, including the effects and interactions of stellar winds and planetary magnetic fields.

From the University of California, Santa Cruz, Jonathan Fortney’s team will investigate how novel statistical methods can be used to extract information from light which is emitted and reflected by planetary atmospheres, in order to understand their atmospheric temperatures and the abundance of molecules.

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NASA GISS to Help Lead Search For Habitable Exoplanets

Left to right: Mars surface air temperatures; hypothetical tidally locked planet; Neoproterozoic Snowball Earth cloud cover; Neoproterozoic Snowball Earth surface wind speed and directions. Credits: NASA GISS and Columbia University

Left to right: Mars surface air temperatures; hypothetical tidally locked planet; Neoproterozoic Snowball Earth cloud cover; Neoproterozoic Snowball Earth surface wind speed and directions. Credits: NASA GISS and Columbia University

NASA announced this week the creation of the Nexus for Exoplanet Systems Science (NExSS) network that will study planets beyond our solar system for habitability and other features tapping the expertise of researchers at NASA’s Goddard Institute for Space Studies (GISS), Goddard Space Flight Center and other locations.

The goal is to take a comprehensive look at known exoplanets and lay the groundwork for interpretation of data from future missions. This includes studies on how chemicals critical to habitability are delivered to planets, how these chemicals are processed by planetary interiors, how the chemicals are released into a planetary atmosphere and escape, how the chemicals combine with the physical and astronomical properties of a planet and the star it orbits to produce a habitable climate, and what we can learn about these processes based on current and future observations.

One team will focus on habitability from a more local perspective by examining the climates of solar system rocky planets through time. That foundation will help inform the detection and characterization of habitable exoplanets in the future. The team is a collaborative effort, led by principal investigator Tony Del Genio of NASA GISS, Shawn Domagal-Goldman of Goddard, Caleb Scharf of Columbia University, and 25 other researchers.

“Our overall guiding question for the project is ‘What is the history of planetary surface habitability in the solar system, and what does this tell us about the potential habitability of planets orbiting other stars?’” said Del Genio.

The heart of the project is the adaptation of the GISS Earth global climate model to simulate other planets, informed by simulations of the orbit histories of the planets to be calculated at Columbia. The model will be used to explore questions about how habitable several planets in our solar system were at different points in their distant past.

“We also plan to use the model to simulate the climates of a wide variety of possible exoplanets to determine which combinations of planetary and planetary system characteristics – atmospheric composition, size, gravity, rotation, orbit, star – are most likely to produce a habitable climate,” Del Genio said.

Team members at Goddard will tie the simulations to data from current NASA missions including the Mars Science Laboratory, Curiosity rover and Kepler space observatory, and incorporate model results into the design of possible future Mars rovers and space-based exoplanet telescopes.

“This research will advance significantly our ability to simulate these worlds in detail, using state-of-the-art tools maintained by the Earth sciences community,” said Shawn Domagal-Goldman, the Goddard lead. “It also will help validate those models by applying them to other solar system planets.”

Additional teams were chosen from the Planetary Science Division portion of the Exoplanets Research Program. One of them is a team from the University of Maryland and Goddard, led by Wade Henning, which will study tidal dynamics and orbital evolution of terrestrial exoplanets. The NExSS network will bring together researchers from different research communities to share their perspectives, research results and approaches. This unprecedented collaboration will help classify the diversity of worlds being discovered, understand the potential habitability of these worlds, and inform the development of tools and technologies needed in the search for life beyond Earth.

NASA GISS is a laboratory in the Earth Sciences Division of NASA’s Goddard Space Flight Center in Greenbelt, Maryland and is affiliated with the Earth Institute and School of Engineering and Applied Science at Columbia University in New York.

For more information on NASA’s Exoplanet Exploration Program, visit: http://science.nasa.gov/about-us/smd-programs/ExEP/

For more information about NASA GISS, visit: http://www.giss.nasa.gov/

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Iron-Rich Rocks Could Hold Signs of Life

The first holes drilled by NASA's Mars Curiosity Rover revealed significant amounts of hematite, an iron-oxide mineral. Credit: NASA

The first holes drilled by NASA’s Mars Curiosity Rover revealed significant amounts of hematite, an iron-oxide mineral. Credit: NASA

A robotic mission’s search for life on Mars may seem worlds away from human scientists wandering around hot springs in Yellowstone National Park. But a study of the Yellowstone hot springs has revealed new clues about how organic materials might get preserved in similar environments on the Red Planet, bettering our chances of finding possible signs of life.

Most studies have focused on the preservation of organic material in silica-rich rocks — the primary source of tiny fossils on Earth that can only be seen with a microscope. But some researchers have begun looking at how iron-rich rocks can also contain possible signs of life. Their Yellowstone hot springs study found that iron could either preserve or react with organic material in a way that helps form a fossil record. Such findings counter previous assumptions that iron-rich rocks would destroy organic material through the chemical reaction known as oxidation.

“In general, many microbes like to ‘eat’ organic compounds, especially certain lipids, for lunch, and can destroy the bulk of the organics before they have a chance to get preserved,” said Mary Parenteau, a research scientist at the SETI Institute, who is also in the exobiology branch of the NASA Ames Research Center. “Iron can rapidly entomb or bind to the organics and make them unavailable to ‘eat,’ similar to encasing a sandwich in cement.”

Parenteau and her colleagues focused on searching for preserved signs of lipids, which are organic molecules that typically form the cell walls and other parts of living organisms on a microscopic scale. They detailed their results in the June 2014 issue of the journal Astrobiology. Funding for the study came in large part from the NASA Exobiology Program.

The route of NASA's Mars Curiosity Rover includes Hematite Ridge, an iron-rich location within the Gale Crater on Mars. Credit: NASA

The route of NASA’s Mars Curiosity Rover includes Hematite Ridge, an iron-rich location within the Gale Crater on Mars. Credit: NASA

Lipids don’t provide as much identifying information about organisms compared to the genetic information of DNA. On the other hand, unlike fragile DNA, lipids have the advantage of potentially leaving their mark for billions of years. Lipids can also hold clues about how microorganisms responded to environmental changes.

The researchers collected samples from both the active Chocolate Pots hot springs in Yellowstone Park and an “extinct” iron-silica hot spring nearby that had long since dried up. They had to tread lightly on the steep slope surrounding the hot springs to avoid disturbing any loose iron sediment that might slide into the water and kill photosynthetic communities of microbes by blocking their access to sunlight. That often required a “delicate balancing act” of stepping carefully on stones strewn across the slope, said Parenteau.

“Often you’re balancing on one foot with both hands full of meters and collecting gear,” Parenteau said. “I practice ‘leave no trace’ sampling, and I care a great deal about minimizing impact at the site.”

The careful sampling paid off. In a sediment core from the active hot spring, researchers found preserved lipid molecules called 2-methylhopanoids belonging to cyanobacteria, a group of bacteria capable of converting sunlight into energy. They even found preserved fragile lipids, such as fatty acids from the cyanobacteria that typically serve as food for other microbes, or are otherwise rapidly destroyed after the cells die.

“When we discovered that the cyanobacterial fatty acids were being preserved in the iron deposits — and were not produced by a deeper chemotrophic community — that forced us to consider ways in which iron may preserve rather than destroy the lipids,” Parenteau explained.

A Chocolate Pots hot spring sampling site in Yellowstone National Park.

A Chocolate Pots hot spring sampling site in Yellowstone National Park.

The iron-rich hot springs may have helped preserve organic molecules such as lipids in several ways. First, iron reacts chemically with oxygen and lowers oxygen levels in the water, which prevents oxygen-dependent bacteria from consuming all the organic material such as lipids. Secondly, iron may block certain enzymes that help break down organic material after the death of microorganisms. Thirdly, iron can even chemically bind with organic molecules to help preserve them.

Robotic missions to Mars have not found signs of active hot springs. But the Spirit Rover discovered evidence of hydrothermal deposits in the Home Plate region that indicated an active hydrothermal system when the dry, dusty Red Planet was younger and held more water. The Mars Science Laboratory Rover, a robot nicknamed Curiosity, has spent time exploring iron-rich rocks located on Hematite Ridge within Gale Crater, the mission’s landing site on Mars.

Parenteau and her colleagues hope that their study’s findings could eventually help future Mars missions — such as NASA’s proposed Mars 2020 rover — hone in on iron-rich rocks that could hold clues to any organic molecules that once existed on the planet. But they also see relevance to studies of ancient life on Earth.

“This work may support a renewed interest in sampling ancient iron deposits on Earth (e.g., Precambrian iron formations) to search for evidence of microbial life, regardless of their low organic carbon content, and may support analysis of organics in iron deposits on Mars, such as Hematite Ridge in Gale Crater,” Parenteau said.

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Astronomers probe inner region of young star and its planets

The planetary system of HR 8799. Most of the light of the star has been erased by the processing of the images and the four planets, identified from b to e in the order of their discovery, are easily detected. A.-L. Maire / LBTO

The planetary system of HR 8799. Most of the light of the star has been erased by the processing of the images and the four planets, identified from b to e in the order of their discovery, are easily detected. A.-L. Maire / LBTO

Astronomers have probed deeper than before into a planetary system 130 light-years from Earth. The observations mark the first results of a new exoplanet survey called LEECH (LBT Exozodi Exoplanet Common Hunt), and are published today in the journal Astronomy and Astrophysics.

The planetary system of HR8799, a young star only 30 million years old, was the first to be directly imaged, with three planets found in in 2008 and a fourth one in 2010.

“This star was therefore a target of choice for the LEECH survey, offering the opportunity to acquire new images and better define the dynamical properties of the exoplanets orbiting,” said Christian Veillet, director of the Large Binocular Telescope Observatory (LBTO).

The LEECH survey began at the Large Binocular Telescope (LBT) in southeastern Arizona in February 2013 to search for and characterize young and adolescent exoplanets in the near-infrared spectrum (specifically, at a wavelength of 3.8 micrometers that astronomers call the L’ band). LEECH exploits the superb performance of the LBT adaptive optics system to image exoplanets with the L/M-band infrared camera (LMIRCam) installed in the LBT Interferometer (LBTI).

“The LBT enables us to look at those planets at a wavelength that nobody else is really using,” Veillet explained. “Because they are gas giants and still very young, they glow nicely at the L’ band, and because they appear so bright there, they stand out, allowing us to observe closer to the star. This has allowed us to nail down the orbits of this system, which is pretty far away.”

“Normally the problem with this approach would be that at 4 microns, telescope optics glow themselves,” said Andy Skemer, a Hubble Fellow at the University of Arizona’s Department of Astronomy and Steward Observatory and the lead of the survey. “However, with LBT, everything about the telescope, its adaptive optics system and science camera have been optimized to minimize this glow. As a result, LEECH is more sensitive than previous exoplanet imaging surveys, and this new image of HR 8799 is proof.”

The study was dedicated to studying the planet architecture of the HR 8799 system, according to the leading author, Anne-Lise Maire, a postdoctoral fellow at INAF-Padova Observatory in Padova, Italy. The team sought to constrain the orbital parameters of the four known giant planets and the physical properties of a putative fifth planet inside the known planets.

The LBTI (green structure in the center of the frame) between the two 8.4m mirrors of the LBT. Credit: LBTO - Enrico Sacchetti

The LBTI (green structure in the center of the frame) between the two 8.4m mirrors of the LBT. Credit: LBTO – Enrico Sacchetti

“To address the first point, we investigated in particular the types of resonances between the planet orbits,” Maire explained. “From the resonances, we learn not only about the overall architecture of the planetary system, but also about the mass range of the planets.”

“They cannot be too massive, or else the system would be dynamically unstable, as previous studies have suggested. Moreover, the presence of resonances between the planets indicates that they gravitationally interact with each other, which gives us a lower limit on their masses.”

The results of this study favor an architecture for the system based on multiple double resonances, in other words, each of the three outer planets takes about twice as long to complete an orbit around the star as its neighbor closer to the star.

“LEECH’s unique sensitivity enabled us to probe the inner region of this planetary system,” added Wolfgang Brandner, a scientist at the Max Planck Institute for Astronomy in Heidelberg, Germany. “A fifth massive giant planet in an inner resonant orbit was excluded. This could mean that the HR 8799 planetary system has an architecture similar to the solar system, with four massive planets at larger distances, and potentially lower mass planets – which haven’t been detected, yet – in the inner planetary system.”

“Our observations give us good idea that this system is pretty stable,” Veillet added, “in other words, there is no indication those planets are going to collide with each other in a few million years.”

In its current configuration, the inner planet LEECH can see approaches the star to about 15 Astronomical Units (AU), Veillet explained, or fifteen times the average distance between the earth and our sun.

“If there were planets of similar brightness closer to the star, we should see it as close as 10 AU,” he said, “which corresponds to the orbit of Saturn.”

According to Veillet, the LEECH survey is an exemplary project in two ways.

“It takes full advantage of the adaptive optics performance offered by our adaptive secondary mirrors, and it combines resources from most of the LBTO partners – four U.S. universities, two institutes in Germany, and the Italian community – to build a large program of more than 100 observing nights. This would not be possible for a single partner on a reasonable time scale.”

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NASA Spacecraft Achieves Unprecedented Success Studying Mercury

NASA’s MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft traveled more than six and a half years before it was inserted into orbit around Mercury on March 18, 2011. Image Credit: NASA/JHU APL/Carnegie Institution of Washington

NASA’s MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft traveled more than six and a half years before it was inserted into orbit around Mercury on March 18, 2011. Image Credit: NASA/JHU APL/Carnegie Institution of Washington

After extraordinary science findings and technological innovations, a NASA spacecraft launched in 2004 to study Mercury will impact the planet’s surface, most likely on April 30, after it runs out of propellant.

NASA’s MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft will impact the planet at more than 8,750 miles per hour (3.91 kilometers per second) on the side of the planet facing away from Earth. Due to the expected location, engineers will be unable to view in real time the exact location of impact.

On Tuesday, mission operators in mission control at the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Maryland, completed the fourth in a series of orbit correction maneuvers designed to delay the spacecraft’s impact into the surface of Mercury. The last maneuver is scheduled for Friday, April 24.

“Following this last maneuver, we will finally declare the spacecraft out of propellant, as this maneuver will deplete nearly all of our remaining helium gas,” said Daniel O’Shaughnessy, mission systems engineer at APL. “At that point, the spacecraft will no longer be capable of fighting the downward push of the sun’s gravity.”

Although Mercury is one of Earth’s nearest planetary neighbors, little was known about the planet prior to the MESSENGER mission.

“For the first time in history we now have real knowledge about the planet Mercury that shows it to be a fascinating world as part of our diverse solar system,” said John Grunsfeld, associate administrator for the Science Mission Directorate at NASA Headquarters in Washington. “While spacecraft operations will end, we are celebrating MESSENGER as more than a successful mission. It’s the beginning of a longer journey to analyze the data that reveals all the scientific mysteries of Mercury.”

The spacecraft traveled more than six and a half years before it was inserted into orbit around Mercury on March 18, 2011. The prime mission was to orbit the planet and collect data for one Earth year. The spacecraft’s healthy instruments, remaining fuel, and new questions raised by early findings resulted in two approved operations extensions, allowing the mission to continue for almost four years and resulting in more scientific firsts.

One key science finding in 2012 provided compelling support for the hypothesis that Mercury harbors abundant frozen water and other volatile materials in its permanently shadowed polar craters.

Data indicated the ice in Mercury’s polar regions, if spread over an area the size of Washington, would be more than two miles thick. For the first time, scientists began seeing clearly a chapter in the story of how the inner planets, including Earth, acquired water and some of the chemical building blocks for life.

A dark layer covering most of the water ice deposits supports the theory that organic compounds,  as well as water, were delivered from the outer solar system to the inner planets and may have led to prebiotic chemical synthesis and, thusly, life on Earth.

“The water now stored in ice deposits in the permanently shadowed floors of impact craters at Mercury’s poles most likely was delivered to the innermost planet by the impacts of comets and volatile-rich asteroids,” said Sean Solomon, the mission’s principal investigator, and director of Columbia University’s Lamont-Doherty Earth Observatory in Palisades, New York. “Those same impacts also likely delivered the dark organic material.”

In addition to science discoveries, the mission provided many technological firsts, including the development of a vital heat-resistant and highly reflective ceramic cloth sunshade that isolated the spacecraft’s instruments and electronics from direct solar radiation – vital to mission success given Mercury’s proximity to the sun. The technology will help inform future designs for planetary missions within our solar system.

“The front side of the sunshade routinely experienced temperatures in excess of 300° Celsius (570° Fahrenheit), whereas the majority of components in its shadow routinely operated near room temperature (20°C or 68°F),” said Helene Winters, mission project manager at APL. “This technology to protect the spacecraft’s instruments was a key to mission success during its prime and extended operations.”

 

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NASA’s Curiosity Rover Making Tracks and Observations

NASA's Curiosity Mars rover used its Navigation Camera (Navcam) to capture this scene toward the west just after completing a drive that took the mission's total driving distance on Mars past 10 kilometers (6.214 miles). Image Credit: NASA/JPL-Caltech

NASA’s Curiosity Mars rover used its Navigation Camera (Navcam) to capture this scene toward the west just after completing a drive that took the mission’s total driving distance on Mars past 10 kilometers (6.214 miles). Image Credit: NASA/JPL-Caltech

NASA’s Curiosity Mars rover is continuing science observations while on the move this month. On April 16, the mission passed 10 kilometers (6.214 miles) of total driving since its 2012 landing, including about a fifth of a mile (310 meters) so far this month.

The rover is trekking through a series of shallow valleys between the “Pahrump Hills” outcrop, which it investigated for six months, and the next science destination, “Logan Pass,” which is still about 200 yards, or meters, ahead toward the southwest.

“We’ve not only been making tracks, but also making important observations to characterize rocks we’re passing, and some farther to the south at selected viewpoints,” said John Grant of the National Air and Space Museum, Washington. Grant is a Curiosity science team member who has been the team’s long-term planner in recent days.

A drive of 208 feet (63.5 meters) during the mission’s 957th Martian day, early Thursday, took Curiosity past a cumulative 10 kilometers of total Martian ground-distance covered. This is based on mapped distance covered by each drive; by wheel odometery, the rover reached 10 kilometers last week, but the mapped tally is considered a more precise measure of distance covered, excluding wheel slippage.

Curiosity is examining the lower slopes of a layered mountain, Mount Sharp, to investigate how the region’s ancient environment evolved from lakes and rivers to much drier conditions. Sites at Pahrump Hills exposed the mountain’s basal geological layer, named the Murray formation. Nearby, high-standing buttes are examples of terrain called the Washboard unit, from its corrugated appearance as seen from orbit.

A green star marks the location of NASA's Curiosity Mars rover after a drive on the mission's 957th Martian day, or sol, (April 16, 2015). The map covers an area about 1.25 miles (2 kilometers) wide. Image Credit: NASA/JPL-Caltech/Univ. of Arizona

A green star marks the location of NASA’s Curiosity Mars rover after a drive on the mission’s 957th Martian day, or sol, (April 16, 2015). The map covers an area about 1.25 miles (2 kilometers) wide. Image Credit: NASA/JPL-Caltech/Univ. of Arizona

“The trough we’re driving through is bounded by exposures of the Washboard unit, with gaps at some places that allow us to see farther south to higher exposures of it,” Grant said. “At Logan Pass, we hope to investigate the relationship between the Murray formation and the Washboard unit, to help us understand the ancient depositional setting and how environmental conditions were changing. The observations we’re making now help establish the context for what we’ll see there.”

“The rover’s mobility has been crucial, because that’s what allows us to get to the best sites to investigate,” Grant said. “The ability to get to different sections of the rock record builds more confidence in your interpretation of each section.”

From observations made by NASA’s Mars Reconnaissance Orbiter, topographically ridged terrain that has beenategorized as the Washboard unit has been mapped at many locations around Mount Sharp — on the south flank of the mountain as well as the northern flank Curiosity is climbing — and on the surrounding plains.

“Understanding the Washboard unit and what processes formed it could put what we’ve been studying into a wider context,” Grant said.

Curiosity spent much of its first 12 months on Mars investigating locations close to its landing site north of Mount Sharp. Findings during that period included evidence for ancient rivers and a lakebed environment that offered conditions favorable for microbial life, if Mars has ever hosted life. After leaving the landing vicinity, Curiosity drove to reach Mount Sharp, with a few extended stops at science waypoints along the route before arriving in September 2014.

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Dawn Glimpses Ceres’ North Pole

This animation shows the north pole of dwarf planet Ceres as seen by the Dawn spacecraft on April 10, 2015. Dawn was at a distance of 21,000 miles (33,000 kilometers) when its framing camera took these images. Image Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

This animation shows the north pole of dwarf planet Ceres as seen by the Dawn spacecraft on April 10, 2015. Dawn was at a distance of 21,000 miles (33,000 kilometers) when its framing camera took these images.
Image Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

After spending more than a month in orbit on the dark side of dwarf planet Ceres, NASA’s Dawn spacecraft has captured several views of the sunlit north pole of this intriguing world. These images were taken on April 10 from a distance of 21,000 miles (33,000 kilometers), and they represent the highest-resolution views of Ceres to date.

Subsequent images of Ceres will show surface features at increasingly better resolution.

Dawn arrived at Ceres on March 6, marking the first time a spacecraft has orbited a dwarf planet. Previously, the spacecraft explored giant asteroid Vesta for 14 months from 2011 to 2012. Dawn has the distinction of being the only spacecraft to orbit two extraterrestrial targets.

Ceres, with an average diameter of about 590 miles (950 kilometers), is the largest body in the main asteroid belt between Mars and Jupiter. Dawn has been using its ion propulsion system to maneuver to its first science orbit at Ceres, which it will reach on April 23.  The spacecraft will remain at a distance of 8,400 miles (13,500 kilometers) from the dwarf planet until May 9. Afterward, it will make its way to lower orbits.

Dawn’s mission is managed by NASA’s Jet Propulsion Laboratory, Pasadena, California, for NASA’s Science Mission Directorate in Washington. Dawn is a project of the directorate’s Discovery Program, managed by NASA’s Marshall Space Flight Center in Huntsville, Alabama. UCLA is responsible for overall Dawn mission science. Orbital ATK, Inc., in Dulles, Virginia, designed and built the spacecraft. The German Aerospace Center, the Max Planck Institute for Solar System Research, the Italian Space Agency and the Italian National Astrophysical Institute are international partners on the mission team. For a complete list of acknowledgements, visit: http://dawn.jpl.nasa.gov/mission

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Search for advanced civilizations beyond Earth finds nothing obvious in 100,000 galaxies

This is a false-color image of the mid-infrared emission from the Great Galaxy in Andromeda, as seen by Nasa's WISE space telescope. The orange color represents emission from the heat of stars forming in the galaxy's spiral arms. The G-HAT team used images such as these to search 100,000 nearby galaxies for unusually large amounts of this mid-infrared emission that might arise from alien civilizations. Credit: NASA/JPL-Caltech/WISE Team

This is a false-color image of the mid-infrared emission from the Great Galaxy in Andromeda, as seen by Nasa’s WISE space telescope. The orange color represents emission from the heat of stars forming in the galaxy’s spiral arms. The G-HAT team used images such as these to search 100,000 nearby galaxies for unusually large amounts of this mid-infrared emission that might arise from alien civilizations. Credit: NASA/JPL-Caltech/WISE Team

After searching 100,000 galaxies for signs of highly advanced extraterrestrial life, a team of scientists using observations from NASA’s WISE orbiting observatory has found no evidence of advanced civilizations in them.

“The idea behind our research is that, if an entire galaxy had been colonized by an advanced spacefaring civilization, the energy produced by that civilization’s technologies would be detectable in mid-infrared wavelengths — exactly the radiation that the WISE satellite was designed to detect for other astronomical purposes,” said Jason T. Wright, an assistant professor of astronomy and astrophysics at the Center for Exoplanets and Habitable Worlds at Penn State University, who conceived of and initiated the research.

The research team’s first paper about its Glimpsing Heat from Alien Technologies Survey (G-HAT), will be published in the Astrophysical Journal Supplement Series on April 15, 2015. Also among the team’s discoveries are some mysterious new phenomena in our own Milky Way galaxy.

“Whether an advanced spacefaring civilization uses the large amounts of energy from its galaxy’s stars to power computers, space flight, communication, or something we can’t yet imagine, fundamental thermodynamics tells us that this energy must be radiated away as heat in the mid-infrared wavelengths,” Wright said. “This same basic physics causes your computer to radiate heat while it is turned on.”

Theoretical physicist Freeman Dyson proposed in the 1960s that advanced alien civilizations beyond Earth could be detected by the telltale evidence of their mid-infrared emissions. It was not until space-based telescopes like the WISE satellite that it became possible to make sensitive measurements of this radiation emitted by objects in space.

Roger Griffith, a postbaccalaureate researcher at Penn State and the lead author of the paper, scoured almost the entire catalog of the WISE satellite’s detections — nearly 100 million entries — for objects consistent with galaxies emitting too much mid-infrared radiation. He then individually examined and categorized around 100,000 of the most promising galaxy images.

Wright reports, “We found about 50 galaxies that have unusually high levels of mid-infrared radiation. Our follow-up studies of those galaxies may reveal if the origin of their radiation results from natural astronomical processes, or if it could indicate the presence of a highly advanced civilization.”

This artist's concept shows the Wide-field Infrared Survey Explorer, or WISE spacecraft, in its orbit around Earth. In September of 2013, engineers will attempt to bring the mission out of hibernation to hunt for more asteroids and comets in a project called NEOWISE. Image credit: NASA/JPL-Caltech

This artist’s concept shows the Wide-field Infrared Survey Explorer, or WISE spacecraft, in its orbit around Earth.  Image credit: NASA/JPL-Caltech

In any case, Wright said, the team’s non-detection of any obvious alien-filled galaxies is an interesting and new scientific result. “Our results mean that, out of the 100,000 galaxies that WISE could see in sufficient detail, none of them is widely populated by an alien civilization using most of the starlight in its galaxy for its own purposes. That’s interesting because these galaxies are billions of years old, which should have been plenty of time for them to have been filled with alien civilizations, if they exist. Either they don’t exist, or they don’t yet use enough energy for us to recognize them,” Wright said.

“This research is a significant expansion of earlier work in this area,” said Brendan Mullan, director of the Buhl Planetarium at the Carnegie Science Center in Pittsburgh and a member of the G-HAT team. “The only previous study of civilizations in other galaxies looked at only 100 or so galaxies, and wasn’t looking for the heat they emit. This is new ground.”

Matthew Povich, an assistant professor of astronomy at Cal Poly Pomona, and a co-investigator on the project, said “Once we had identified the best candidates for alien-filled galaxies, we had to determine whether they were new discoveries that needed follow-up study, or well-known objects that had a lot of mid-infrared emission for some natural reason.” Jessica Maldonado, a Cal Poly Pomona undergraduate, searched the astronomical literature for the best of the objects detected as part of the study to see which were well known and which were new to science. “Ms. Maldonado discovered that about a half dozen of the objects are both unstudied and really interesting looking,” Povich said.

“When you’re looking for extreme phenomena with the newest, most sensitive technology, you expect to discover the unexpected, even if it’s not what you were looking for,” said Steinn Sigurdsson, professor of astronomy and astrophysics at Penn State’s Center for Exoplanets and Habitable Worlds and a co-investigator on the research team. “Sure enough, Roger and Jessica did find some puzzling new objects. They are almost certainly natural astronomical phenomena, but we need to study them more carefully before we can say for sure exactly what’s going on.”

Among the discoveries within our own Milky Way galaxy are a bright nebula around the nearby star 48 Librae, and a cluster of objects easily detected by WISE in a patch of sky that appears totally black when viewed with telescopes that detect only visible light. “This cluster is probably a group of very young stars forming inside a previously undiscovered molecular cloud, and the 48 Librae nebula apparently is due to a huge cloud of dust around the star, but both deserve much more careful study,” Povich said.

“As we look more carefully at the light from these galaxies,” said Wright, “we should be able to push our sensitivity to alien technology down to much lower levels, and to better distinguish heat resulting from natural astronomical sources from heat produced by advanced technologies. This pilot study is just the beginning.”

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Glitter Cloud May Serve as Space Mirror

This image shows laser light reflected off of a glitter mirror onto a camera sensor. Researchers tested this in a laboratory as part of the concept of "Orbiting Rainbows," a low-cost solution for space telescope mirrors. Credit: G. Swartzlander/Rochester Institute of Technology

This image shows laser light reflected off of a glitter mirror onto a camera sensor. Researchers tested this in a laboratory as part of the concept of “Orbiting Rainbows,” a low-cost solution for space telescope mirrors. Credit: G. Swartzlander/Rochester Institute of Technology

What does glitter have to do with finding stars and planets outside our solar system? Space telescopes may one day make use of glitter-like materials to help take images of new worlds, according to researchers at NASA’s Jet Propulsion Laboratory in Pasadena, California.

Standard telescopes use solid mirrors to image far-away objects. But the large, complex mirrors needed for astronomy can be quite expensive and difficult to construct. Their size and weight also add to the challenges of launching a space telescope in the first place.

A concept called Orbiting Rainbows seeks to address these issues. Researchers propose using clouds of reflective glitter-like particles in place of mirrors to enable a telescope to view stars and exoplanets. The technology would enable high-resolution imaging at a fraction of the cost.

“It’s a floating cloud that acts as a mirror,” said Marco Quadrelli from JPL, the Orbiting Rainbows principal investigator. “There is no backing structure, no steel around it, no hinges; just a cloud.”

In the proposed Orbiting Rainbows system, the small cloud of glitter-like grains would be trapped and manipulated with multiple laser beams. The trapping happens because of pressure from the laser light — specifically, the momentum of photons translates into two forces: one that pushes particles away, and another that pushes the particles toward the axis of the light beam. The pressure of the laser light coming from different directions shapes the cloud and pushes the small grains to align in the same direction. In a space telescope, the tenuous cloud would be formed by millions of grains, each possibly as small as fractions of a millimeter in diameter.

Researchers made a mirror surface out of glitter to test the idea of using a cloud of reflective particles as a space telescope mirror. They took images of two light sources using this mirror in a laboratory at Rochester Institute of Technology. Credit: G. Swartzlander/Rochester Institute of Technology

Researchers made a mirror surface out of glitter to test the idea of using a cloud of reflective particles as a space telescope mirror. They took images of two light sources using this mirror in a laboratory at Rochester Institute of Technology. Credit: G. Swartzlander/Rochester Institute of Technology

Such a telescope would have a wide adjustable aperture, the space through which light passes during an optical or photographic measurement; in fact, it might lead to possibly larger apertures than those of existing space telescopes.

It would also be much simpler to package, transport and deploy, than a conventional space telescope.

“You deploy the cloud, trap it and shape it,” Quadrelli said.

Nature is full of structures that have light-scattering and focusing properties, such as rainbows, optical phenomena in clouds, or comet tails. Observations of these phenomena, and recent laboratory successes in optical trapping and manipulation have contributed to the Orbiting Rainbows concept. The original idea for a telescope based on a laser-trapped mirror was proposed in a 1979 paper by astronomer Antoine Labeyrie at the College de France in Paris.

Now, the Orbiting Rainbows team is trying to identify ways to manipulate and maintain the shape of an orbiting cloud of dust-like matter using laser pressure so it can function as an adaptive surface with useful electromagnetic characteristics, for instance, in the optical or radar bands.

Because a cloud of glitter specks is not a smooth surface, the image produced from those specks in a telescope will be noisier — with more speckled distortion — than what a regular mirror would generate. That’s why researchers are developing algorithms to take multiple images and computationally remove the speckle effect from the glitter.

To test the idea, co-investigator Grover Swartzlander, an associate professor at the Rochester Institute of Technology in New York, and his students spread glitter on a concave lens in the laboratory. His team used lasers to represent the light from a double star system. They pointed the speckled mirror at the simulated stars, then used a camera to take pictures. With many exposures and lots of processing, an image of the two “stars” emerged using the glitter mirror.

“This is a major achievement,” Quadrelli said. “This demonstrates a highly controlled experiment in which we were able to do imaging in the visible light spectrum.”

 

The technology could be used more easily for radio-band signals. Because the wavelength is so much longer (about one centimeter, compared to nanometers in visible light), the mirror grains don’t have to be as precisely controlled or aligned. This opens up Earth science applications such as earthquake detection and remote sensing of water and other phenomena. JPL’s Darmindra Arumugam is investigating possible mechanisms for remote sensing with Orbiting Rainbows.

The JPL optical design team, including Scott Basinger and Mayer Rud, has been working on the adaptive optics techniques that would be needed by an Orbiting Rainbows telescope. So far, the team has been exploring reflective, refractive and diffractive versions of a telescope based on Orbiting Rainbows, with maximum sensitivity to one specific frequency.

Orbiting Rainbows has not yet been demonstrated in space. For a test in low-Earth orbit, the researchers would deploy a telescope with a small patch of particles, no larger than a bottle cap, to show that it can be trapped and shaped to reflect light. The next step would be to make many of these patches and synthesize an aperture with which to do imaging.

The project represents a new application of “granular matter,” materials such as dust grains, powders and aerosols. Such materials are very light, can be produced at low-cost and could be useful to the space exploration community. In this particular project, the “glitter” may be tiny granules of metallic-coated plastic, quartz or some other material.

Orbiting Rainbows is currently in Phase II development through the NASA Innovative Advanced Concepts (NIAC) Program. It was one of five technology proposals chosen for continued study in 2014. In the current phase, Orbiting Rainbows researchers are conducting small-scale ground experiments to demonstrate how granular materials can be manipulated using lasers and simulations of how the imaging system would behave in orbit.

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New source of methane discovered in the Arctic Ocean

This image shows the bathymetry of the area of the Arctic Ocean where the new source of methane was found: Knipovich Ridge in the Fram Strait. Credit: CAGE

This image shows the bathymetry of the area of the Arctic Ocean where the new source of methane was found: Knipovich Ridge in the Fram Strait. Credit: CAGE

Methane, a highly effective greenhouse gas, is usually produced by decomposition of organic material, a complex process involving bacteria and microbes.

But there is another type of methane that can appear under specific circumstances: Abiotic methane is formed by chemical reactions in the oceanic crust beneath the seafloor.

New findings show that deep water gas hydrates, icy substances in the sediments that trap huge amounts of the methane, can be a reservoir for abiotic methane. One such reservoir was recently discovered on the ultraslow spreading Knipovich ridge, in the deep Fram Strait of the Arctic Ocean. The study suggests that abiotic methane could supply vast systems of methane hydrate throughout the Arctic.

The study was conducted by scientists at Centre for Arctic Gas Hydrate, Environment and Climate (CAGE) at UiT The Arctic Univeristy of Norway. The results were recently published in Geology online and will be featured in the journal’s May issue.

Previously undescribed

“Current geophysical data from the flank of this ultraslow spreading ridge shows that the Arctic environment is ideal for this type of methane production. ” says Joel Johnson associate professor at the University of New Hampshire (USA), lead author, and visiting scholar at CAGE.

This is a previously undescribed process of hydrate formation; most of the known methane hydrates in the world are fueled by methane from the decomposition of organic matter.

“It is estimated that up to 15 000 gigatonnes of carbon may be stored in the form of hydrates in the ocean floor, but this estimate is not accounting for abiotic methane. So there is probably much more.” says co-author and CAGE director Jürgen Mienert.

89985_webLife on Mars?

NASA has recently discovered traces of methane on the surface of Mars, which led to speculations that there once was life on our neighboring planet. But an abiotic origin cannot be ruled out yet.

On Earth it forms through a process called serpentinization.

“Serpentinization occurs when seawater reacts with hot mantle rocks exhumed along large faults within the seafloor. These only form in slow to ultraslow spreading seafloor crust. The optimal temperature range for serpentinization of ocean crust is 200 – 350 degrees Celsius.” says Johnson.

Methane produced by serpentinization can escape through cracks and faults, and end up at the ocean floor. But in the Knipovich Ridge it is trapped as gas hydrate in the sediments. How is it possible that relatively warm gas becomes this icy substance?

“In other known settings the abiotic methane escapes into the ocean, where it potentially influences ocean chemistry. But if the pressure is high enough, and the subseafloor temperature is cold enough, the gas gets trapped in a hydrate structure below the sea floor. This is the case at Knipovich Ridge, where sediments cap the ocean crust at water depths up to 2000 meters. ” says Johnson.

Stable for two million years

Another peculiarity about this ridge is that because it is so slowly spreading, it is covered in sediments deposited by fast moving ocean currents of the Fram Strait. The sediments contain the hydrate reservoir, and have been doing so for about 2 million years.

” This is a relatively young ocean ridge, close to the continental margin. It is covered with sediments that were deposited in a geologically speaking short time period -during the last two to three million years. These sediments help keep the methane trapped in the sea floor.” says Stefan Bünz of CAGE, also a co-author on the paper.

Samples of the gas hydrates will provide more knowledge on abiotic methane. But they need to be drilled, as they are 140 meters under the ocean floor. Photo: Wikimedia Commons.

Samples of the gas hydrates will provide more knowledge on abiotic methane. But they need to be drilled, as they are 140 meters under the ocean floor. Photo: Wikimedia Commons.

Bünz says that there are many places in the Arctic Ocean with a similar tectonic setting as the Knipovich ridge, suggesting that similar gas hydrate systems may be trapping this type of methane along the more than 1000 km long Gakkel Ridge of the central Arctic Ocean.

The Geology paper states that such active tectonic environments may not only provide an additional source of methane for gas hydrate, but serve as a newly identified and stable tectonic setting for the long-term storage of methane carbon in deep-marine sediments.

Need to drill

The reservoir was identified using CAGE’s high resolution 3D seismic technology aboard research ressel Helmer Hanssen. Now the authors of the paper wish to sample the hydrates 140 meters below the ocean floor, and decipher their gas composition.

Knipovich Ridge is the most promising location on the planet where such samples can be taken, and one of the two locations where sampling of gas hydrates from abiotic methane is possible.

” We think that the processes that created this abiotic methane have been very active in the past. It is however not a very active site for methane release today. But hydrates under the sediment, enable us to take a closer look at the creation of abiotic methane through the gas composition of previously formed hydrate.” says Jürgen Mienert who is exploring possibilities for a drilling campaign along ultra-slow spreading Arctic ridges in the future.

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Life’s Building Blocks Recreated Under Space-Like Conditions

Credit: NASA/JPL-Caltech

Credit: NASA/JPL-Caltech

Researchers have reproduced a wide array of building blocks for life in a prebiotic scenario involving meteorites and the solar wind.

They began with formamide, a simple organic compound that’s ubiquitous in the universe. Formamide has been detected in galactic centers, star-forming regions, interstellar space, as well as comets and satellites.

They then added meteorite powder as a catalyst, and irradiated the solution with high-energy proton beams to simulate the solar wind. They obtained a rich blend of complex biological molecules including amino acids, carboxylic acids, sugars, and nucleobases (the basic building blocks for DNA and RNA).

Among the products were also the nucleosides cytidine, uridine, adenosine, and thymidine, which are more advanced building blocks consisting of a nucleobase linked to a sugar molecule. Nucleosides are notoriously difficult to recreate under prebiotic conditions.

“We were very surprised to see those,” says Raffaele Saladino of Tuscia University, Italy.

The ingredients for life have previously been recreated under a variety of possible terrestrial scenarios involving lightning, ultraviolet radiation, hydrothermal vents, or meteorite impacts. The new findings expand the range of possibilities to prebiotic environments beyond the early Earth, including to the small, wandering bodies of our solar system.

The results were published this week in the Proceedings of the National Academy of Sciences.

Solar Wind Power

The team had previously synthesized some of the building blocks (but no nucleosides) by subjecting formamide to very high temperatures, simulating conditions near volcanoes or upon meteorite impact on the early Earth.

Formamide, a one-carbon compound that may have served as parent molecule for many of life’s building blocks

Formamide, a one-carbon compound that may have served as parent molecule for many of life’s building blocks

By instead irradiating formamide with high-energy protons, they obtained a higher yield of amino acids and nucleobases, as well as other relevant biomolecules including the nucleosides.

“Proton chemistry goes one step farther than heat chemistry,” says study co-author Ernesto Di Mauro of the University of Rome La Sapienza.“Proton radiation turns out to be amazingly efficient.”

He adds: “Carbon chemistry works the same anywhere in the universe, and every star produces solar wind. This tells us that life could well be universal.”

Interestingly, the scenario produced a high quantity of precursors for both metabolic and genetic pathways (the carboxylic acids and nucleobases respectively.) An ongoing debate with the origin of life is whether metabolism or genetics emerged first. Here, the findings suggest that both processes could have emerged simultaneously.

Meteorites as Reactors

Other findings have also suggested that meteorites may have seeded the ingredient for life on the early Earth, notably during the Late Heavy Bombardment, a period when the inner planets were pummeled by frequent impacts about 4.1 to 3.8 billion years ago. In particular, some simple amino acids, sugars, and nucleobases have been found inside meteorites, albeit in very small proportions.

Here, the researchers wanted to go beyond the idea of meteorites as mere carriers of organic molecules. They tested the catalytic properties of eleven meteorites belonging to the four major classes—iron, stony iron, chondrites, and achondrites—but first treated the rock powder to remove any trace of organics.

They found that the minerals within the meteorites were necessary to catalyze the synthesis of the molecules, with the stony iron, chondrite, and achondrite meteorites more active than the iron meteorites as a general trend. They also tested individual minerals present in the meteorites and found that the full powder was needed for full catalytic effect.

“Meteorites are not merely shuttles for organics, as suggests the common point of view,” Saladino says. “They are also reactors that can synthesize biomolecules during their lives.”

Comets and asteroids pummeled the inner planets of our young solar system during the Late Heavy Bombardment. Credit: NASA/JPL-Caltech

Comets and asteroids pummeled the inner planets of our young solar system during the Late Heavy Bombardment. Credit: NASA/JPL-Caltech

The Catch

The findings come with an important caveat. “I’m extremely enthusiastic about this piece of work because they obtained much more than the nucleobases,” says Steven Benner, an origin-of-life chemist at the Foundation for Applied Molecular Evolution at the Westheimer Institute in Gainesville, Fla. “They combined formamide and rock chemistry and got so many building blocks—that’s what makes this paper important.”

“But the catch is that the total mass of meteorite that’s coming in after the Moon-forming event is negligible,” he adds. “You can’t rely on the Late Heavy Bombardment to bring you much in terms of organics. Besides, that amount of carbon is negligible compared to what’s here on Earth already.”

Indeed, formamide, the starting molecule in their experiment, is readily made from hydrogen cyanide and water — two compounds that were abundant on the early Earth.

“My view is that we have to solve the problem with what’s here on Earth before we go looking at meteorites,” Benner said, “just because of the amount of material that’s coming in.”

Reference: Saladino, et al. 2015. Meteorite-catalyzed syntheses of nucleosides and of other prebiotic compounds from formamide under proton irradiation. PNAS http://www.pnas.org/content/early/2015/04/08/1422225112.abstract

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