Archives

April 2017


DGIST research team led by Professor CheolGi Kim has developed a biosensor platform which has 20 times faster detection capability than the existing biosensors using magnetic patterns resembling a spider web.

I am currently attending the Astrobiology Science Conference where the world's astrobiologists all meet to showcase their results and share ideas. There was a time, barely 20 years ago, when there were no astrobiologists. I was one of the lucky people to be present as this amazing 21st century discipline came into existence.

When it comes to exploring exoplanets, it may be wise to take a snorkel along. A new study, published in a paper in the journal Monthly Notices of the Royal Astronomical Society, has used a statistical model to predict that most habitable planets may be dominated by oceans spanning over 90% of their surface area.

Keith's note: This coming week I will be at the Astrobiology Science Conference (AbSciCon). I will be tweeting about the meeting from @NASAWatch and @Astrobiology and posting updates at astrobiology.com. AbSciCon Sessions will be streamed live at http://astrobiology.nasa.gov/livestream

Day Two of Breakthrough Discuss opened with Michaƫl Gillon describing the discovery of TRAPPIST-1, which has seven temperate planets, including three in the habitable zone.

The first day of Breakthrough Discuss 2017 explored planets around nearby stars and their potential for life. Charles Alcock opened the conference with the statement that, "The far-fetched ideas of today are the discoveries of tomorrow," and Peter Michelson emphasized that the last century of scientific investigation has transformed questions about origins from the realm of metaphysics to a place where they can be investigated observationally.

Earth-like, potentially habitable exoplanets are prime targets in the search for extraterrestrial life. Information about their atmosphere and surface can be derived by analyzing light of the parent star reflected by the planet.

H2O is a key molecule in characterizing atmospheres of temperate terrestrial planets, and observations of transmission spectra are expected to play a primary role in detecting its signatures in the near future.

Few places are as hostile to life as Chile's Atacama Desert. It's the driest place on Earth, and only the hardiest microbes survive there. Its rocky landscape has lain undisturbed for eons, exposed to extreme temperatures and radiation from the sun.

Cosmic rays are an important factor of space weather determining radiation conditions near the Earth and it seems to be essential to clarify radiation conditions near extrasolar planets too. Last year a terrestrial planet candidate was discovered in an orbit around Proxima Centauri.

Breakthrough Listen - the initiative to find signs of intelligent life in the universe - has released its 11 events ranked highest for significance as well as summary data analysis results.

Breakthrough Initiatives today announced its second annual Breakthrough Discuss scientific conference, which will bring together leading astronomers, engineers, astrobiologists and astrophysicists to advance discussion surrounding recent discoveries of potentially habitable planets in nearby star systems. The conference will take place on Thursday, April 20 and Friday, April 21, at Stanford University and will be webcast live.

Current protoplanetary dust coagulation theory does not predict dry silicate planetesimals, in tension with the Earth. While remedies to this predicament have been proposed, they have generally failed numerical studies, or are in tension with the Earth's (low, volatility dependent) volatile and moderately volatile elemental abundances.

M dwarf stars, which have masses less than 60 per cent that of the Sun, make up 75 per cent of the population of the stars in the Galaxy [1]. The atmospheres of orbiting Earth-sized planets are observationally accessible via transmission spectroscopy when the planets pass in front of these stars [2,3].

An exoplanet orbiting a red dwarf star 40 light-years from Earth may be the new holder of the title "best place to look for signs of life beyond the Solar System". Using ESO's HARPS instrument at La Silla, and other telescopes around the world, an international team of astronomers discovered a "super-Earth" orbiting in the habitable zone around the faint star LHS 1140.

The recent discovery of seven potentially habitable Earth-size planets around the ultra-cool star TRAPPIST-1 has further fueled the hunt for extraterrestrial life. Current methods focus on closely monitoring the host star to look for biomarkers in the transmission signature of exoplanet's atmosphere. However, the outcome of these methods remain uncertain and difficult to disentangle with abiotic alternatives.

The newly detected TRAPPIST-1 system, with seven low-mass, roughly Earth-sized planets transiting a nearby ultra-cool dwarf, is one of the most important exoplanet discoveries to date.

It has recently been proposed that Earth-like planets in the outer regions of the habitable zone experience unstable climates, repeatedly cycling between glaciated and deglaciated climatic states (Menou 2015).

Water and hydroxyl, once thought to be found only in the primitive airless bodies that formed beyond roughly 2.5-3 AU, have recently been detected on the Moon and Vesta, which both have surfaces dominated by evolved, non-primitive compositions. In both these cases, the water/OH is thought to be exogenic, either brought in via impacts with comets or hydrated asteroids or created via solar wind interactions with silicates in the regolith or both.

We have just discovered a transiting terrestrial planet in a small nearby star's habitable zone. Due to the proximity of the host star and the size of the transit depth, possible constituents for this planet's atmosphere can be detected with the Hubble Space Telescope. Here we propose to use STIS to obtain observations of the host star at Lyman-alpha.

Evidence for plumes of water on Europa has previously been found using the Hubble Space Telescope (HST) using two different observing techniques. Roth et al. (2014) found line emission from the dissociation products of water. Sparks et al. (2016) found evidence for off-limb continuum absorption as Europa transited Jupiter.

With two suns in its sky, Luke Skywalker's home planet Tatooine in "Star Wars" looks like a parched, sandy desert world.

On Thursday NASA will announce evidence that hydrothermal activity on the floor of an ice-covered ocean on Saturn's moon Enceladus is most likely creating methane from carbon dioxide. The process is indicative of possible habitable zones within the ocean of Enceladus.

But before we go any further, "habitable" does not mean "inhabited".

We searched high resolution spectra of 5600 nearby stars for emission lines that are both inconsistent with a natural origin and unresolved spatially, as would be expected from extraterrestrial optical lasers.

The Kepler mission has revealed that Earth-sized planets are common, and dozens have been discovered to orbit in or near their host star's habitable zone. A major focus in astronomy is to determine which of these exoplanets are likely to have Earth-like properties that are amenable to follow-up with both ground- and future space-based surveys, with an ultimate goal of probing their atmospheres to look for signs of life. Venus-like atmospheres will be of particular interest in these surveys.

TRAPPIST-1 is a late M-dwarf orbited by seven Earth-sized planets with orbital period ratios near a chain of mean motion resonances. Due to uncertain system parameters, most orbital configurations drawn from the inferred posterior distribution are unstable on short timescales, even when including the eccentricity damping effect of tides.

Earth is the only planet known to harbor life, therefore we may speculate on how the nature of the Sun-Earth interaction is relevant to life on Earth, and how the behavior of other stars may influence the development of life on their planetary systems.

Astronomers have detected an atmosphere around the super-Earth GJ 1132b. This marks the first detection of an atmosphere around a low-mass Super-Earth, in terms of radius and mass the most Earth-like planet around which an atmosphere has yet been detected.

Want to go ice fishing on Jupiter's moon Europa? There's no promising you'll catch anything, but a new set of robotic prototypes could help.

With several short-period, Earth-mass planets in the habitable zone, the TRAPPIST-1 system potentially allows litho-panspermia to take place on very short timescales. We investigate the efficiency and speed of inter-planetary material transfer resulting from impacts onto the habitable zone planets.

UV observations with Cassini ISS Narrow Angle Camera of Titan's detached haze is an excellent tool to probe its aerosols content without being affected by the gas or the multiple scattering. Unfortunately, its low extent in altitude requires a high resolution calibration and limits the number of images available in the Cassini dataset.

Why are the terrestrial planets so different? Venus should be the most Earth-like of all our planetary neighbours. Its size, bulk composition and distance from the Sun are very similar to those of the Earth.

We consider a dynamical shake-up model to explain the low mass of Mars and the lack of planets in the asteroid belt. In our scenario, a secular resonance with Jupiter sweeps through the inner solar system as the solar nebula depletes, pitting resonant excitation against collisional damping in the Sun's protoplanetary disk.

We investigate the feasibility of detecting water molecules (H2O) and water ions (H20+) from the Europa plumes from a flyby mission. A Monte Carlo particle tracing method is used to simulate the trajectories of neutral particles under the influence of Europa's gravity field and ionized particles under the influence of Jupiter's magnetic field and the convectional electric field.

Understanding the limits on what microbial life can endure is important for preventing contamination of the Red Planet with terrestrial microbes when our human and robotic explorers arrive.