Archives

March 2020


In Jessica Barnes' palm is an ancient, coin-sized mosaic of glass, minerals and rocks as thick as a strand of wool fiber. It is a slice of Martian meteorite, known as Northwest Africa 7034 or Black Beauty, that was formed when a huge impact cemented together various pieces of Martian crust.

The available models of global climate evolution in habitable earthlike planets do not consider the effect of salt content in oceans, which affects water evaporation.

Based on numbers of stars, supernova rates, and metallicity, a prior study (Dayal et al. 2015) concluded that large elliptical galaxies contain up to 10,000 times more habitable planets than the Milky Way and are thus the "cradles of life".

In the present chapter we present the results of evolutionary studies of exoplanetary atmospheres. We mostly focus on the sub- to super-Earth domain, although these methods are applicable to all types of exoplanets.

The mass extinction at the end of the Permian Peri od 252 million years ago -- one of the great turnovers of life on Earth -- appears to have played out differently and at different times on land and in the sea, according to newly redated fossils beds from South Africa and Australia.

Cornell University astronomers have created five models representing key points from our planet's evolution, like chemical snapshots through Earth's own geologic epochs.

Transmission spectroscopy is a powerful technique widely used to probe exoplanet terminators. Atmospheric retrievals of transmission spectra are enabling comparative studies of exoplanet atmospheres.

Since the launch of Kepler and Hubble more than a decade ago, we have come a long way in the quest to find a potentially habitable exoplanet. To date, we have already discovered more than 4000 exoplanets most of which are not suitable for sustaining life.

In this work is investigated the possibility of close-binary star systems having Earth-size planets within their habitable zones.

While exoplanets are now routinely detected, the detection of small bodies in extrasolar systems remains challenging. Since the discovery of sporadic events interpreted as exocomets (Falling Evaporating Bodies) around β Pic in the early 80s, only ∼20 stars have been reported to host exocomet-like events.

We propose several descriptive measures to characterize the arrangements of planetary masses, periods, and mutual inclinations within exoplanetary systems. These measures are based in complexity theory and capture the global, system-level trends of each architecture.

The composition of an atmosphere has integrated the geological history of the entire planetary body. However, the long-term evolutions of the atmospheres of the terrestrial planets are not well documented.

Shungite, a unique carbon-rich sedimentary rock from Russia that deposited 2 billion years ago, holds clues about oxygen concentrations on Earth's surface at that time.

Polycyclic Aromatic Hydrocarbon (PAH) molecules have been long adjudged to contribute to the frequently detected distinct emission features at 3.3, 6.2, 7.7, 8.6, 11.2 and 12.7 {\mu}m with weaker and blended features distributed in the 3-20 {\mu}m region.

Polycyclic aromatic hydrocarbon (PAH) molecules, as revealed by the distinctive set of emission bands at 3.3, 6.2, 7.7, 8.6, 11.3 and 12.7 μm characteristic of their vibrational modes, are abundant and widespread throughout the Universe.

Solar system materials are variably depleted in moderately volatile elements (MVEs) relative to the proto-solar composition.

From modeling the evolution of disks of planetesimals under the influence of planets, it has been shown that the mass of water delivered to the Earth from beyond Jupiter's orbit could be comparable to the mass of terrestrial oceans.

The discovery of ubiquitous habitable extrasolar planets, combined with revolutionary advances in instrumentation and observational capabilities, has ushered in a renaissance in the search for extra-terrestrial intelligence (SETI).

Context: In the laboratory, hydrogen peroxide (HOOH) was proven to be an intermediate product in the solid-state reaction scheme that leads to the formation of water on icy dust grains. When HOOH desorbs from the icy grains, it can be detected in the gas phase.

Assuming our Solar System as typical, exomoons may outnumber exoplanets. If their habitability fraction is similar, they would thus constitute the largest portion of habitable real estate in the Universe.

Aims. Formamide (HCONH2) is the simplest molecule containing the peptide bond first detected in the gas phase in Orion-KL and SgrB2. In recent years, it has been observed in high temperature regions such as hot corinos, where thermal desorption is responsible for the sublimation of frozen mantles into the gas phase.

After hydrogen, oxygen, and carbon, nitrogen is one of the most chemically active species in the interstellar medium (ISM). Nitrogen bearing molecules have great importance as they are actively involved in the formation of biomolecules.

The search for life on planets beyond our solar system has long been the purview of science fiction, but a UC Santa Barbara team supported by the Heising-Simons Foundation is now building the technology to do just that.

A new study by an international team of scientists has revealed the developmental and evolutionary mechanisms underlying the origin of a major phylum.

Researchers have designed a new camera that could allow hypertelescopes to image multiple stars at once. The enhanced telescope design holds the potential to obtain extremely high-resolution images of objects outside our solar system, such as planets, pulsars, globular clusters and distant galaxies.

Water plumes erupting from the `tiger stripe' features on the south pole of Enceladus are thought to connect to a global subsurface ocean.

Most planets currently amenable to transit spectroscopy are close enough to their host star to exhibit a relatively strong day to night temperature gradient. For hot planets, this leads to cause a chemical composition dichotomy between the two hemispheres.

New research raises the possibility that some parts of Mercury's subsurface, and those of similar planets in the galaxy, once could have been capable of fostering prebiotic chemistry, and perhaps even simple life forms, according to a paper by a team led by Planetary Science Institute Research Scientist Alexis Rodriguez.

Europa's surface reflectance exhibits a pronounced hemispheric dichotomy, which is hypothesized to form due to enhanced irradiation of the trailing hemisphere by energetic particles entrained in the jovian magnetosphere.

Space radiation is a major risk for humans, especially on long-duration missions to outer space, e.g., a manned mission to Mars.

New research lends credence to an unorthodox retelling of the story of early Earth first proposed by a geophysicist at Scripps Institution of Oceanography at UC San Diego.

A key factor in determining the potential habitability of synchronously rotating planets is the strength of the atmospheric boundary layer inversion between the dark side surface and the free atmosphere.

One popular view of Venus' climate history describes a world that has spent much of its life with surface liquid water, plate tectonics, and a stable temperate climate.

Spearheaded by earth scientists of the University of Cologne, an international team of geologists has found evidence that a large proportion of the elements that are important for the formation of oceans and life, such as water, carbon and nitrogen, were delivered to Earth very late in its history.

Comets and asteroids are objects in our solar system that have not developed much since the planets were formed. As a result, they are in a sense the archives of the solar system, and determining their composition could also contribute to a better understanding of the formation of the planets.

We explore the chemistry and observability of nitrogen dominated atmospheres for ultra-short-period super-Earths. We base the assumption, that super-Earths could have nitrogen filled atmospheres, on observations of 55 Cnc e that favour a scenario with a high-mean-molecular-weight atmosphere.

Researchers supported in part by the NASA Astrobiology Program have attempted to better understand global barometric pressure on Earth during the Archaean by studying vesicle sizes in 2.9 billion year-old lavas that erupted near sea level.

Scientists supported in part by the NASA Astrobiology Program have provided new details of how the Hooggeneoeg Formation in South Africa was formed. The Hooggeneoeg Formation is found in the Barberton Greenstone Belt, and holds some of the best-preserved examples of supracrustal rocks from the mid-Archean (3.5 to 3.2 billion years ago).

The behavior of one of nature's humblest creatures is helping astronomers probe the largest structures in the universe. The single-cell organism, known as slime mold (Physarum polycephalum), builds complex filamentary networks in search of food, finding near-optimal pathways to connect different locations.

We present the results of an independent search of all ~200,000 stars observed over the four year Kepler mission (Q1-Q17) for multiplanet systems, using a three-transit minimum detection criteria to search orbital periods up to hundreds of days.

In evaluating the number of technological civilizations N in the Galaxy through the Drake formula, emphasis is mostly put on the astrophysical and biotechnological factors describing the emergence of a civilization and much less on its the lifetime, which is intimately related to its demise.

The NASA Science Mission Directorate is soliciting community feedback and recommendations on the structure and science goals of the NASA Astrobiology Program's Research Coordination Network (RCN) focused on "Early Cells to Multicellularity" (ECM) research. Responses to this Request for Information (RFI) will be used by NASA to further inform planning and development of the ECM RCN and to ensure that this RCN is scoped to advance the big science questions in this research area.

To help answer one of the great existential questions--how did life begin?--a new study combines biological and cosmological models. Professor Tomonori Totani from the Department of Astronomy looked at how life's building blocks could spontaneously form in the universe--a process known as abiogenesis.

Before the Taqba Dam impounded the Euphrates River in northern Syria in the 1970s, an archaeological site named Abu Hureyra bore witness to the moment ancient nomadic people first settled down and started cultivating crops. A large mound marks the settlement, which now lies under Lake Assad

Earth turned faster at the end of the time of the dinosaurs than it does today, rotating 372 times a year, compared to the current 365, according to a new study of fossil mollusk shells from the late Cretaceous. This means a day lasted only 23 and a half hours, according to the new study in AGU's journal Paleoceanography and Paleoclimatology.

Little is known about the interaction between atmospheres and crusts of exoplanets so far, but future space missions and ground-based instruments are expected to detect molecular features in the spectra of hot rocky exoplanets.

The habitability of the surface of any planet is determined by a complex evolution of its interior, surface, and atmosphere. The electromagnetic and particle radiation of stars drive thermal, chemical and physical alteration of planetary atmospheres, including escape.

Organic compounds called thiophenes are found on Earth in coal, crude oil and oddly enough, in white truffles, the mushroom beloved by epicureans and wild pigs.

More than half of the planet's fresh water is in Antarctica. While most of it is frozen in the ice sheets, underneath the ice pools and streams of water flow into one another and into the Southern Ocean surrounding the continent.

Due to its Earth-like minimum mass of 1.27 ME and its close proximity to our Solar system, Proxima Centauri b is one of the most interesting exoplanets for habitability studies.

Are advanced civilizations in our galaxy trying to communicate with us by means of laser blasts? A team of University of California, San Diego, UC Berkeley, Harvard University and California Institute of Technology astronomers are building a pair of fly's-eye observatories to find out.

New research led by scientists from the University of Bristol has revealed new insights into how the microscopic algae that thrives along the edge of the Greenland Ice Sheet causes widespread darkening.

The steady advances in computer performance and in programming raise the concern that the ability of computers would overtake that of the human brain, an occurrence termed "the Singularity".

The detection of complex organic molecules (COMs) toward dense, collapsing prestellar cores has sparked interest in the fields of astrochemistry and astrobiology, yet the mechanisms for COM formation are still debated.

Context. As a building block for amino acids, formamide (NH2CHO) is an important molecule in astrobiology and astrochemistry, but its formation path in the interstellar medium is not understood well.

Earth-Like is an interactive website and twitter bot that allows users to explore changes in the average global surface temperature of an Earth-like planet due to variations in the surface oceans and emerged land coverage, rate of volcanism (degassing), and the level of the received solar radiation.

Recent analysis of the planet K2-18b has shown the presence of water vapour in its atmosphere. While the H2O detection is significant, the Hubble Space Telescope (HST) WFC3 spectrum suggests three possible solutions of very different nature which can equally match the data.

We use a new interdisciplinary approach to study the UV surface habitability of Proxima b under quiescent and flaring stellar conditions. We assumed planetary atmospheric compositions based on CO2 and N2 and surface pressures from 100 to 5000 mbar.

Since the discovery of submarine hydrothermal vents around 40 years ago, these natural chemical reactors have been a focus for evolutionary researchers searching for the origin of life.

Chemical changes in the oceans more than 800 million years ago almost destroyed the oxygen-rich atmosphere that paved the way for complex life on Earth, new research suggests.

New research shows that the early Earth, home to some of our planet's first lifeforms, may have been a real-life "waterworld"-- without a continent in sight. The study, which appears March 2 in Nature Geoscience, takes advantage of a quirk of hydrothermal chemistry to suggest that the surface of Earth was likely covered by a global ocean 3.2 billion years ago.

Researchers from Chalmers University of Technology, Sweden, have made a new contribution to the ongoing search into the possibility of life on Titan, Saturn's largest moon.

Asteroid strikes upset the environment and provide clues via the elements they leave behind.

The search for spectroscopic biosignatures with the next-generation of space telescopes could provide observational constraints on the abundance of exoplanets with signs of life.

The search for different life forms elsewhere in the universe is a fascinating area of research in astrophysics and astrobiology. Currently, according to the NASA Exoplanet Archive database, 3876 exoplanets have been discovered.

H2CO is one of the most abundant organic molecules in protoplanetary disks and can serve as a precursor to more complex organic chemistry. We present an ALMA survey of H2CO towards 15 disks covering a range of stellar spectral types, stellar ages, and dust continuum morphologies.