Archives

September 2013


Chemical disequilibrium has recently become a relevant topic in the study of the atmospheres of of transiting extrasolar planets, brown dwarfs, and directly imaged exoplanets. We present a new way of assessing whether or not a Jovian-like atmosphere is in chemical disequilibrium from observations of detectable or inferred gases such as H$_2$O, CH$_4$, CO, and H$_2$.

The quest for evidence of life on Mars could be more difficult than scientists previously thought. A scientific paper published today details the investigation of a chemical in the Martian soil that interferes with the techniques used by the Curiosity rover to test for traces of life. The chemical causes the evidence to burn away during the tests.

During the Archean eon, between about 3.8 billion years ago and 2.5 billion years ago, the Sun was about 20 to 25 percent fainter than it is today. With less sunlight to warm the Earth, the oceans should have been frozen over, but geological evidence suggests that this was not the case.

The National Aeronautics and Space Administration (NASA) Science Mission Directorate (SMD) is releasing a Cooperative Agreement Notice (NNH13ZDA017C) entitled NASA Astrobiology Institute (NAI) - Cycle 7.

Earth's Habitable Lifetime

Findings published today in the journal Astrobiology reveal the habitable lifetime of planet Earth - based on our distance from the sun and temperatures at which it is possible for the planet to have liquid water.

The John W. Kluge Center at the Library of Congress is now accepting applications for the Baruch S. Blumberg NASA/Library of Congress Chair in Astrobiology. The deadline is December 1.

Recent simulations have shown that the formation of planets in circumbinary configurations (such as those recently discovered by Kepler) is dramatically hindered at the planetesimal accretion stage.

The Voyager 1 flyby of Titan in 1980 gave a first glimpse of the chemical complexity of Titan's atmosphere, detecting many new molecules with the infrared spectrometer (IRIS). These included propane (C3H8) and propyne (CH3C2H), while the intermediate-sized C3Hx hydrocarbon (C3H6) was curiously absent. Using spectra from the Composite Infrared Spectrometer (CIRS) on Cassini, we show the first positive detection of propene (C3H6) in Titan's stratosphere (5-sigma significance), finally filling the three-decade gap in the chemical sequence.

Astrobiology: An Astronomer's Perspective

In this review we explore aspects of the field of astrobiology from an astronomical viewpoint. We therefore focus on the origin of life in the context of planetary formation, with additional emphasis on tracing the most abundant volatile elements, C, H, O, and N that are used by life on Earth.

Glimpses of the events that nurtured life on Earth more than 3.5 billion years ago are coming from an unlikely venue almost 1 billion miles away, according to the leader of an effort to understand Titan, one of the most unusual moons in the solar system.

Scientists have discovered a 'cosmic factory' for producing the building blocks of life, amino acids, according to research.

Astrobiology Strategic Plan Milestone

The NASA Astrobiology Strategy process has reached an important milestone. The concept documents, which were created at the Wallops Island workshop, are now ready for public comment.

Could Life Have Survived a Fall to Earth?

It sounds like science fiction, but the theory of panspermia, in which life can naturally transfer between planets, is considered a serious hypothesis by planetary scientists. The suggestion that life did not originate on Earth but came from elsewhere in the universe (for instance, Mars), is one possible variant of panspermia. a.

Detecting Biomarkers on Faraway Planets

On Earth, life leaves telltale signals in the atmosphere. Photosynthesis is ultimately responsible for the high oxygen levels and the thick ozone layer. Microbes emit methane and nitrous oxide into the atmosphere, and seaweeds emit chloromethane gas.

Evidence of diverse life forms dating back nearly a hundred thousand years has been found in subglacial lake sediments by a group of British scientists.

A novel, hybrid part-human, part-machine visual system that uses a simple mobile phone camera has been developed to search for evidence of past or present life in planetary analogue sites on Earth. Patrick McGuire from the Freie Universitaet, Berlin, will present results from this Cyborg Astrobiologist at the European Planetary Science Congress in London on Monday 9th September.

An instrument similar to those used on Earth by art detectives and to sense explosives at airports will be taken into space for the first time by ExoMars, the European Space Agency's mission to Mars in 2018. This Raman spectrometer will help space scientists to hunt for traces of Martian life.

New research has revealed that chemical reactions previously thought to be 'impossible' in space actually occur 'with vigour,' a discovery that could ultimately change our understanding of how alcohols are formed and destroyed in space - and which could also mean that places like Saturn's moon Titan, once considered too cold for life to form, may have a shortcut for biochemical reactions.

The field of exoplanetary science has experienced a recent surge of new systems that is largely due to the precision photometry provided by the Kepler mission. The latest discoveries have included compact planetary systems in which the orbits of the planets all lie relatively close to the host star, which presents interesting challenges in terms of formation and dynamical evolution.

We describe and report first results from PALM-3000, the second-generation astronomical adaptive optics facility for the 5.1-m Hale telescope at Palomar Observatory.

With most planets and planetary candidates detected in the stellar habitable zone being super-Earths and gas giants, rather than Earth-like planets, we naturally wonder if their moons could be habitable.

Habitable Worlds With No Signs of Life

'Most habitable worlds in the cosmos will have no remotely detectable signs of life' is proposed as a biological hypothesis to be tested in studies of exoplanets. Habitable planets could be discovered elsewhere in the Universe, yet there are many hypothetical scenarios whereby the search for life on them could yield negative results.

How many different molecules can be created when you release one of the universe's most reactive substances, hydrogen cyanide, in the lab? And will the process create some particularly interesting molecules?

In today's mailing, Hogg et al. propose image modeling techniques to maintain 10-ppm-level precision photometry in Kepler data with only two working reaction wheels.

A large fraction of white dwarfs (WDs) may host planets in their habitable zones. These planets may provide our best chance to detect bio-markers on a transiting exoplanet, thanks to the diminished contrast ratio between the Earth-sized WD and its Earth-sized planets.

Observations of the Earth as a planet using the earthshine technique (i.e. looking at the light reflected from the darkside of the Moon), have been used for climate and astrobiology studies.

Astrometry is a powerful technique to study the populations of extrasolar planets around nearby stars. It gives access to a unique parameter space and is therefore required for obtaining a comprehensive picture of the properties, abundances, and architectures of exoplanetary systems.

We report our spectroscopic investigation of the transiting ice giant GJ 3470b's atmospheric transmission, and the first results of extrasolar planet observations from the new Keck/MOSFIRE spectrograph.

The Blue Sky of GJ3470b

GJ3470b is a rare example of a "hot Uranus" transiting exoplanet orbiting a nearby M1.5 dwarf. It is of crucial interest for atmospheric studies because it is one of the most inflated low-mass planets known, bridging the boundary between "super-Earths" and Neptunian planets.