Archives

September 2020


The matter between the stars in a galaxy - called the interstellar medium - consists not only of gas, but also of a great deal of dust.

NASA's Mars 2020 Perseverance rover has a challenging road ahead: After having to make it through the harrowing entry, descent, and landing phase of the mission on Feb. 18, 2021, it will begin searching for traces of microscopic life from billions of years back.

University of Warwick astronomers have shown that water vapour can potentially be detected in the atmospheres of exoplanets by peering literally over the tops of their impenetrable clouds.

Recently, phosphine was discovered in the atmosphere of Venus as a potential biosignature.

Direct imaging of widely separated exoplanets from space will obtain their reflected light spectra and measure atmospheric properties.

New composite images made from NASA's Cassini spacecraft are the most detailed global infrared views ever produced of Saturn's moon Enceladus. And data used to build those images provides strong evidence that the northern hemisphere of the moon has been resurfaced with ice from its interior.

M dwarf stars are excellent candidates around which to search for exoplanets, including temperate, Earth-sized planets. To evaluate the photochemistry of the planetary atmosphere, it is essential to characterize the UV spectral energy distribution of the planet's host star.

Recent miniaturization of electronics in very small, low-cost and low-power configurations suitable for use in spacecraft have inspired innovative small-scale satellite concepts, such as ChipSats, centimeter-scale satellites with a mass of a few grams.

The disequilibrium combination of abundant methane and carbon dioxide has been proposed as a promising exoplanet biosignature that is readily detectable with upcoming telescopes such as the James Webb Space Telescope.

Small organic molecules are thought to provide building blocks for the formation of complex interstellar polycyclic aromatic hydrocarbons (PAHs).

The putative detection of phosphine in the atmosphere of Venus at an abundance of ∼20 ppb suggests that this gas is being generated by either indeterminate abiotic pathways or biological processes.

In a little more than a decade, samples of rover-scooped Martian soil will rocket to Earth.

The near-term search for life beyond the solar system currently focuses on transiting planets orbiting small M dwarfs, and the challenges of detecting signs of life in their atmospheres.

When stars like our sun die, all that remains is an exposed core - a white dwarf. A planet orbiting a white dwarf presents a promising opportunity to determine if life can survive the death of its star, according to Cornell University researchers.

Although Earth is uniquely situated in the solar system to support creatures that call it home, different forms of life could have once existed, or might still exist, on other planets. But finding traces of past or current lifeforms on other worlds is challenging.

For terrestrial exoplanets with thin atmospheres or no atmospheres, the surface contributes light to the reflected light signal of the planet.

A new planet has been recently discovered around Proxima Centauri. With an orbital separation of ∼1.44 au and a minimum mass of about 7 M⊕, Proxima c is a prime direct imaging target for atmospheric characterization.

We revisit the hypothesis that there is life in the Venusian clouds to propose a life cycle that resolves the conundrum of how life can persist aloft for hundreds of millions to billions of years.

The recent candidate detection of 20 ppb of phosphine in the middle atmosphere of Venus is so unexpected that it requires an exhaustive search for explanations of its origin. Phosphorus-containing species have not been modelled for Venusian atmosphere before and our work represents the first attempt to model phosphorus species in Venusian atmosphere.

Measurements of trace-gases in planetary atmospheres help us explore chemical conditions different to those on Earth. Our nearest neighbor, Venus, has cloud decks that are temperate but hyper-acidic. We report the apparent presence of phosphine (PH3) gas in Venusian atmosphere, where any phosphorus should be in oxidized forms.

An international team of astronomers today announced the discovery of a rare molecule -- phosphine -- in the clouds of Venus. On Earth, this gas is only made industrially or by microbes that thrive in oxygen-free environments.

Keith's note: There is a big press release coming out tomorrow (Monday, 14 September) morning at the Royal Astronomical Society. They want you to know its big news. The press release has been issued in advance to some journalists under embargo - but not others (like us). We have not seen the press release. But according to several sources knowledgeable with the details of the announcement (who are not under embargo) phosphine has been discovered in the atmosphere of Venus. Its presence suggests - suggests - some strange chemistry going on since phosphine is something you'd only expect to see if life (as we know it) was involved.

Keith's 14 Sep update: Apparently the RAS has changed its mind about how it is going to do their big announcement and a live stream will be presented at 11:00 am EDT here: https://www.youtube.com/watch?v=5IIj3e5BFp0

Jupiter's moons are hot. Well, hotter than they should be, for being so far from the Sun. In a process called tidal heating, gravitational tugs from Jupiter's moons and the planet itself stretch and squish the moons enough to warm them.

Callisto is thought to possess a subsurface ocean, which will dissipate energy due to obliquity tides. This dissipation should have damped any primordial inclination within 1 Gyr - and yet Callisto retains a present-day inclination.

We have investigated the possible evolutional history of the water ocean on Venus, adopting the one dimensional radiative-convective model, including the parameters as albedo and relative humidity.

Space weather plays an important role in the evolution of planetary atmospheres. Observations have shown that stellar flares emit energy in a wide energy range (10^30-10^38 ergs), a fraction of which lies in X-rays and extreme ultraviolet (XUV).

Chondrites, the building blocks of the terrestrial planets, have mass and atomic proportions of oxygen, iron, magnesium, and silicon totaling ≥90% and variable Mg/Si (∼25%), Fe/Si (factor of ≥2), and Fe/O (factor of ≥3).

Perhaps as far back as the history of research and philosophy goes, people have attempted to unearth how life on earth came to be.

New research led by the American Museum of Natural History and funded by NASA identifies a process that might have been key in producing the first organic molecules on Earth about 4 billion years ago, before the origin of life. The process, which is similar to what might have occurred in some ancient underwater hydrothermal vents, may also have relevance to the search for life elsewhere in the universe. Details of the study are published this week in the journal Proceedings of the National Academy of Sciences.

Following the results of our previous low frequency searches for extraterrestrial intelligence (SETI) using the Murchison Widefield Array (MWA), directed toward the Galactic Centre and the Orion Molecular Cloud (Galactic Anticentre), we report a new large-scale survey toward the Vela region with the lowest upper limits thus far obtained with the MWA.

The identification of extraterrestrial life is one the most exciting and challenging endeavors in space research. The existence of extinct or extant life can be inferred from biogenic elements, isotopes, and molecules, but accurate and sensitive instruments are needed.

In anticipation of future flagship missions focused on the goal of achieving direct imaging of rocky exoplanets, we have developed a database of models to help the community examine the potential spectral characteristics of a broad range of rocky planet atmospheres.

High levels of X-ray and UV activity on young M dwarfs may drive rapid atmospheric escape on temperate, terrestrial planets orbiting within the liquid water habitable zone.

NASA should design missions to Mars for the purpose of generating "Aha!" discoveries to jolt scientists contemplating the molecular origins of life.

Viruses are often thought of as a human problem, however they are the most abundant biological entities on the planet. There are millions of viruses in every teaspoon of river, lake or seawater, they are found everywhere there is life and probably infect all living organisms.

Breakthrough Listen (the initiative to find signs of intelligent life in the universe) and the University of Manchester announced today a reanalysis of existing data that represents a new milestone in the search for extraterrestrial intelligence (SETI).

What if impact craters, long seen as harbingers of death, turned out to be the cradle of life?

When searching for exoplanets and ultimately considering their habitability, it is necessary to consider the planet's composition, geophysical processes, and geochemical cycles in order to constrain the bioessential elements available to life.

The atmospheric circulation of tidally locked planets is dominated by a superrotating eastward equatorial jet.

Several concepts have been brought forward to determine where terrestrial planets are likely to remain habitable in multi-stellar environments. Isophote-based habitable zones, for instance, rely on insolation geometry to predict habitability, whereas Radiative Habitable Zones take the orbital motion of a potentially habitable planet into account.

Comets likely formed in the outer regions of the protosolar nebula where they incorporated and preserved primitive presolar materials, volatiles resident in the outer disk, and more refractory materials from throughout the disk.

NASA Goddard Institute for Space Studies (GISS) scientists leveraged NASA supercomputing resources for several months to model a hypothetical climate history for Venus over the past 4.2 billion years.