Archives

July 2020


The methane cycle is a key component of the Earth system that links planetary climate, biological metabolism, and the global biogeochemical cycles of carbon, oxygen, sulfur, and hydrogen.

Understanding the total flux and polarization signals of Earth-like planets and their spectral and temporal variability is essential for the future characterization of such exoplanets.

NASA Launched the Mars 2020 rover Perseverance today. As Perseverance departs it leaves a troubled world behind to explore a new one in search of life. At the Perseverance post-launch media event I asked NASA Administrator Jim Bridenstine and Science Mission Directorate Associate Administrator Thomas Zurbuchen about exploring a new world during such difficult times.

NASA's Mars 2020 will land in Jezero Crater, pictured here. The image was taken by instruments on NASA's Mars Reconnaissance Orbiter, which regularly takes images of potential landing sites for future missions.

For decades, scientists have gathered ancient sediment samples from below the seafloor to better understand past climates, plate tectonics and the deep marine ecosystem. In a new study published in Nature Communications, researchers reveal that given the right food in the right laboratory conditions, microbes collected from sediment as old as 100 million years can revive and multiply, even after laying dormant since large dinosaurs prowled the planet.

We advocate for the realization of volatile sample return from various destinations including: small bodies, the Moon, Mars, ocean worlds/satellites, and plumes. As part of recent mission studies (e.g., Comet Astrobiology Exploration SAmple Return (CAESAR) and Mars Sample Return), new concepts, technologies, and protocols have been considered for specific environments and cost.

When the Shewanella oneidensis bacterium "breathes" in certain metal and sulfur compounds anaerobically, the way an aerobic organism would process oxygen, it produces materials that could be used to enhance electronics, electrochemical energy storage, and drug-delivery devices.

Scientists from the UK are playing a vital role in a NASA mission to Mars set to launch this Thursday (30 July).

At least twice in Earth's history, nearly the entire planet was encased in a sheet of snow and ice. These dramatic "Snowball Earth" events occurred in quick succession, somewhere around 700 million years ago, and evidence suggests that the consecutive global ice ages set the stage for the subsequent explosion of complex, multicellular life on Earth.

Although no life has been detected on the Martian surface, a new study from astrophysicist and research scientist at the Center for Space Science at NYU Abu Dhabi, Dimitra Atri finds that conditions below the surface could potentially support it.

ESA's ExoMars Trace Gas Orbiter has spotted new gas signatures at Mars. These unlock new secrets about the martian atmosphere, and will enable a more accurate determination of whether there is methane, a gas associated with biological or geological activity, at the planet.

Photometric variability of a directly imaged exo-Earth conveys spatial information on its surface and can be used to retrieve a two-dimensional geography and axial tilt of the planet (spin-orbit tomography).

Using radial-velocity data from the Habitable-zone Planet Finder, we have measured the mass of the Neptune-sized planet K2-25b, as well as the obliquity of its M4.5-dwarf host star in the 600-800MYr Hyades cluster.

The greatest hazard for humans on deep-space exploration missions is radiation. To protect astronauts venturing out beyond Earth's protective magnetosphere and sustain a permanent presence on Moon and/or Mars, advanced passive radiation protection is highly sought after.

Perennially ice-covered lakes that host benthic microbial ecosystems are present in many regions of Antarctica. Lake Untersee is an ultra-oligotrophic lake that is substantially different from any other lakes on the continent as it does not develop a seasonal moat and therefore shares similarities to sub-glacial lakes where they are sealed to the atmosphere.

The discovery of the first active methane seep in Antarctica is providing scientists new understanding of the methane cycle and the role methane found in this region may play in warming the planet.

Living under a translucent rock can be quite comfortable -- if you're a moss in the Mojave Desert.

AbGradE has canceled in-person meetings for 2020 but will hold a "Virtual AbGradE 2020" on 26th August, 2020, immediately preceding the virtual EANA 2020 meeting.

Hydrogen in rocky planet atmospheres has been invoked in arguments for extending the habitable zone via N2-H2 and CO2-H2 greenhouse warming, and providing atmospheric conditions suitable for efficient production of prebiotic molecules.

Previous studies have shown that sea-ice drift effectively promote the onset of a globally ice-covered snowball climate for paleo Earth and for tidally locked planets around low-mass stars.

Astrochemical modeling is needed for understanding the formation and evolution of interstellar molecules, and for extracting physical information from spectroscopic observation of molecular lines.

The surface of Europa is geologically young and shows signs of current activity. Studying it from a photometric point of view gives us insight on its physical state.

Most electrical activity in vertebrates and invertebrates occurs at extremely low frequencies, and the origin -- and medical potential -- of these frequencies have eluded scientists.

Our sister planet Venus could serve as a model for many exoplanets soon to be discovered in the upcoming era of new space telescopes, such as James Webb and others.

The rediscovery of a lost planet could pave the way for the detection of a world within the habitable 'Goldilocks zone' in a distant solar system.

Bioinformatics and big data analyses can reap great rewards for biologists, but it takes a lot of work to generate the datasets necessary to begin.

Many exoplanets known today are "super-Earths", with a radius 1.3 times that of Earth, and "mini-Neptunes", with 2.4 Earth radii.

Icy satellites represent compelling astrobiological targets, but their rocky interiors must be better characterized.

Several exoplanets have been discovered to date, and the next step is the search for extraterrestrial life.

Scientists have found the interstellar organic matter could produce an abundant supply of water by heating, suggesting that organic matter could be the source of terrestrial water.

Microbial life is known to survive in all sorts of extreme environments by going into a dormant state. Could they have survived long trips around our galaxy to seed life on Earth? Astrobiologist Nicol Caplin talks extreme life in this episode of Meet The Experts.

Nuclear spectroscopy is the only instrumentation that provides bulk geochemical constraints at depth (up to one meter in the surface). These instruments identify and quantify water and other key elements relevant to planetary exploration, including assessing planetary processes, context in the search for life, and in-situ resource utilization.

The search for exoplanetary life must encompass the complex geological processes reflected in an exoplanet's atmosphere, or we risk reporting false positive and false negative detections.

Aims: The secondary atmospheres of terrestrial planets form and evolve as a consequence of interaction with the interior over geological time. We aim to quantify the influence of planetary bulk composition on interior--atmosphere evolution to aid the interpretation of future observations of terrestrial exoplanet atmospheres.

Caltech microbiologists have discovered bacteria that feed on manganese and use the metal as their source of calories. Such microbes were predicted to exist over a century ago, but none had been found or described until now.

Since mRNAs play a key role in protein synthesis in vivo, the use of mRNAs as medicines and for in vitro protein synthesis has been desired.

Despite the fact that the majority of current models assume that interstellar complex organic molecules (iCOMs) are formed on dust-grain surfaces, there is some evidence that neutral gas-phase reactions play an important role.

The impact event that formed the Chicxulub crater (Yucatán Peninsula, México) caused the extinction of 75% of species on Earth 66 million years ago, including non-avian dinosaurs.

We study whether polycyclic aromatic hydrocarbons (PAHs) can be a weighty source of small hydrocarbons in photo-dissociation regions (PDRs).

We discuss the results of a remote sensing study that has revealed new details about an important rock unit dominated by two minerals that can be associated with volcanism (olivine) and life (carbonate).

We combine analytical understanding of resonant dynamics in two-planet systems with machine learning techniques to train a model capable of robustly classifying stability in compact multi-planet systems over long timescales of 109 orbits.

Step aside, skeletons -- a new world of biochemical "signatures" found in all kinds of ancient fossils is revealing itself to paleontologists, providing a new avenue for insights into major evolutionary questions.

Observations suggest an abundance of water and paucity of methane in the majority of observed exoplanetary atmospheres. We isolate the effect of atmospheric processes to investigate possible causes.

Microbial cells are found in abundance in marine sediments beneath the ocean and make up a significant amount of the total microbial biomass on the planet.

Enceladus is believed to have a saltwater global ocean with a mean depth of at least 30~km, heated from below at the ocean-core interface and cooled at the top, where the ocean loses heat to the icy lithosphere above.

Observational data suggest that a belt of planetesimals is expected close to the snow line in protoplanetary disks. Assuming there is such a belt in TRAPPIST-1 system, we examine possibilities of water delivery to the planets via planetesimals from the belt.

Habitability has been generally defined as the capability of an environment to support life. Ecologists have been using Habitat Suitability Models (HSMs) for more than four decades to study the habitability of Earth from local to global scales.

We present a new scaling law to predict the loss of atmosphere from planetary collisions for any speed, angle, impactor mass, target mass, and body compositions, in the regime of giant impacts onto broadly terrestrial planets with relatively thin atmospheres.

Protoplanets are able to accrete primordial atmospheres when embedded in the gaseous protoplanetary disk. The formation and structure of the proto-atmosphere are subject to the planet--disk environment and orbital effects.

Synchronously orbiting, tidally-locked exoplanets with a dayside facing their star and a permanently dark nightside orbiting dim stars are prime candidates for habitability. Simulations of these planets often show the potential to maintain an Earth-like climate with a complete hydrological cycle.

It is well known since 2010 that fullerene C60 is widespread through the interstellar space. Also, it is well known that graphene is a source material for synthesizing fullerene. Here, we simply assume the occurrence of graphene in space.

Over 200 molecules have been detected in multiple extraterrestrial environments, including glycolaldehyde (C2(H2O)2, GLA), a two-carbon sugar precursor that has been detected in regions of the interstellar medium.

Geological evidence suggests liquid water near the Earth's surface as early as 4.4 gigayears ago when the faint young Sun only radiated about 70 % of its modern power output.

TRAPPIST-1 is a fantastic nearby (~39.14 light years) planetary system made of at least seven transiting terrestrial-size, terrestrial-mass planets all receiving a moderate amount of irradiation. To date, this is the most observationally favourable system of potentially habitable planets.

The nearby super-Earth 55 Cnc e orbits a bright (V = 5.95 mag) star with a period of ~ 18 hours and a mass of ~ 8 Earth masses. Its atmosphere may be water-rich and have a large scale-height, though attempts to characterize it have yielded ambiguous results.

The authors and co-signers of the Terrestrial Planets Comparative Climatology (TPCC) mission concept white paper advocate that planetary science in the next decade would greatly benefit from comparatively studying the fundamental behavior of the atmospheres of Venus and Mars, contemporaneously and with the same instrumentation, to capture atmospheric response to the same solar forcing, and with a minimum of instrument-related variability.

As dying stars take their final few breaths of life, they gently sprinkle their ashes into the cosmos through the magnificent planetary nebulae. These ashes, spread via stellar winds, are enriched with many different chemical elements, including carbon.

The Late Devonian was a protracted period of low speciation resulting in biodiversity decline, culminating in extinction events near the Devonian-Carboniferous boundary. Recent evidence indicates that the final extinction event may have coincided with a dramatic drop in stratospheric ozone, possibly due to a global temperature rise.

The search for life in the universe is currently focused on Earth-analog planets. However, we should be prepared to find a diversity of terrestrial exoplanets not only in terms of host star but also in terms of surface environment.

Are there hurricanes on exoplanets? Tidally locked terrestrial planets around M dwarfs are the main targets of space missions for finding habitable exoplanets. Whether hurricanes can form on this kind of planet is important for their climate and habitability.

We present Cassini VIMS observations of sun glitter -- wave-induced reflections from a liquid surface offset from a specular point -- on Kraken Mare. Sun glitter reveals rough sea surfaces around Kraken Mare, namely the coasts and narrow straits.

In recent years, a plethora of high spectral resolution observations of sub-mm and FIR transitions of methylidene (CH), have demonstrated this radical to be a valuable proxy for H2, that can be used for characterising molecular gas within the interstellar medium (ISM) on a Galactic scale, including the CO-dark component.

Ancient Venus and Earth may have been similar in crucial ways for the development of life, such as liquid water oceans, land-ocean interfaces, the favorable chemical ingredients and energy pathways.

JWST will provide moderate resolution transit spectra with continuous wavelength coverage from the optical to the mid-infrared for the first time. In this paper, we illustrate how different aerosol species, size-distributions, and spatial distributions encode information in JWST transit spectra.