The tell-tale signature of the molecule methane in the atmosphere of the Jupiter-sized extrasolar planet HD 189733b has been found with the Hubble Space Telescope. Under the right circumstances methane can play a key role in prebiotic chemistry -- the chemical reactions considered necessary to form life as we know it. Although methane has been detected on most of the planets in our Solar System, this is the first time any organic molecule has been detected on a world orbiting another star.

 

This discovery proves that Hubble and upcoming space missions, such as the NASA/ESA/CSA James Webb Space Telescope, can detect organic molecules on planets around other stars by using spectroscopy, which splits light into its components to reveal the "fingerprints" of various chemicals.

"This is a crucial stepping stone to eventually characterising prebiotic molecules on planets where life could exist", said Mark Swain of NASA's Jet Propulsion Laboratory (JPL), Pasadena, USA, who led the team that made the discovery. Swain is lead author of a paper in the 20 March issue of Nature.

The discovery comes after extensive observations made in May 2007 with Hubble's Near Infrared Camera and Multi-Object Spectrometer (NICMOS). It also confirms the existence of water molecules in the planet's atmosphere, a discovery made originally by NASA's Spitzer Space Telescope in 2007. "With this observation there is no question whether there is water or not -- water is present", said Swain.

The planet, HD 189733b, now known to have methane and water vapour is located 63 light-years away in the constellation Vulpecula, the little fox. HD 189733b, a "hot Jupiter"-type extrasolar planet, is so close to its parent star that it takes just over two days to complete an orbit. "Hot Jupiters" are the size of Jupiter but orbit closer to their stars than the tiny innermost planet Mercury in our Solar System. HD 189733b's atmosphere swelters at 900 degrees C, about the same temperature as the melting point of silver.

The observations were made as the planet HD 189733b passed in front of its parent star in what astronomers call a transit. As the light from the star passed briefly through the atmosphere along the edge of the planet, the gases in the atmosphere imprinted their unique signatures on the starlight from the star HD 189733. According to co-author Giovanna Tinetti from the University College London and the European Space Agency: "Water alone could not explain all the spectral features observed. The additional contribution of methane is necessary to fit the Hubble data".

Methane, composed of carbon and hydrogen, is one of the main components of natural gas, a petroleum product. On Earth, methane is produced by a variety of sources: natural sources such as termites, the oceans and wetland environments, but also from livestock and manmade sources like waste landfills and as a by-product of energy generation. Tinetti is however quick to rule out any biological origin of the methane found on HD 189733b. "The planet's atmosphere is far too hot for even the hardiest life to survive -- at least the kind of life we know from Earth. It's highly unlikely that cows could survive here!"

The astronomers were surprised to find that the planet has more methane than predicted by conventional models for "hot Jupiters". This type of hot planet should have much more carbon monoxide than methane but HD 189733b doesn't. Tinetti explains: "A sensible explanation is that the Hubble observations were more sensitive to the dark night side of this planet where the atmosphere is slightly colder and the photochemical mechanisms responsible for methane destruction are less efficient than on the day side".

Though the star-hugger planet is too hot for life as we know it, "this observation is proof that spectroscopy can eventually be done on a cooler and potentially habitable Earth-sized planet orbiting a dimmer red dwarf-type star", Swain said. The ultimate goal of studies like these is to identify prebiotic molecules in the atmospheres of planets in the "habitable zones" around other stars, where temperatures are right for water to remain liquid rather than freeze or evaporate away.

"These measurements are an important step to our ultimate goal of determining the conditions, such as temperature, pressure, winds, clouds, etc., and the chemistry on planets where life could exist. Infrared spectroscopy is really the key to these studies because it is best matched to detecting molecules", said Swain.

 

From:http://www.sciencedaily.com/releases/2008/03/080319140759.htm

 

Researchers at the National Institute of Standards and Technology (NIST) and the Joint Quantum Institute (NIST/University of Maryland) have developed a new method for creating pairs of entangled photons, particles of light whose properties are interlinked in a very unusual way dictated by the rules of quantum physics. The researchers used the photons to test fundamental concepts in quantum theory.

 

In the experiment, the researchers send a pulse of light into both ends of a twisted loop of optical fiber. Pairs of photons of the same color traveling in either direction will, every so often, interact in a process known as "four-wave mixing," converting into two new, entangled photons, one that is redder and the other that is bluer than the originals.

Although the fiber's twist means that pairs emerging from one end are vertically polarized (having electric fields that vibrate up and down) while pairs from the other end are horizontally polarized (vibrating side to side), the setup makes it impossible to determine which path the newly created photon pairs took. Since the paths are indistinguishable, the weird rules of quantum physics say that the photon pairs actually will be in both states--horizontal and vertical polarization--at the same time. Until someone measures one, at which time both photons must chose one specific, and identical, state.

This "spooky action at a distance" is what caused Einstein to consider quantum mechanics to be incomplete, prompting debate for the past 73 years over the concepts of "locality" and "realism." Decades of experiments have demonstrated that measurements on pairs of entangled particles don't agree with the predictions made by "local realism," the concept that processes occurring at one place have no immediate effect on processes at another place (locality) and that the particles have definite, preexisting properties (called "hidden variables") even without being measured (realism).

Experiments so far have ruled out locality and realism as a combination. But could a theory assuming only one of them be correct" Nonlocal hidden variables (NLHV) theories would allow for the possibility of hidden variables but would concede nonlocality, the idea that a measurement on a particle at one location may have an immediate effect on a particle at a separate location.

Measuring the polarizations of the pairs of entangled particles in their setup, the researchers showed that the results did not agree with the predictions of certain NLHV theories but did agree with the predictions of quantum mechanics. In this way, they were able to rule out certain NLHV theories. Their results agree with other groups that have performed similar experiments.

* J. Fan, M.D. Eisaman and A. Migdall, Bright phase-stable broadband fiber-based source of polarization-entangled photon pairs. Physical Review A 76, 043836 (2007). 

** M.D. Eisaman, E.A. Goldschmidt, J. Chen, J. Fan and A. Migdall. Experimental test of non-local realism using a fiber-based source of polarization-entangled photon pairs. Physical Review A., upcoming.

 

From:http://www.sciencedaily.com/releases/2008/03/080318174941.htm

 

The UK’s national computing grid, along with their counterparts in the US (TeraGrid) and Europe have helped UCL (University College London) scientists shed light on how life on earth may have originated.

 

Deep ocean hydrothermal vents have long been suggested as possible sources of biological molecules such as RNA and DNA but it was unclear how they could survive the high temperatures and pressures that occur round these vents.

Professor Peter Coveney and colleagues at the UCL Centre for Computational Science have used computer simulation to provide insight into the structure and stability of DNA while inserted into layered minerals. Computer simulation techniques have rarely been used to understand the possible chemical pathways to the formation of early biomolecules until now.

Professor Coveney explains, “Computational grids are only now being made easy to use for scientists, enabling simulations of sufficient size to model these large biomolecule and mineral systems”.

Previous experimental studies have shown that molecules such as DNA can be inserted into minerals called layered double hydroxides (LDHs) but no one has thus far been able to show at the level of atoms and molecules how the DNA interacts with the mineral, or how the DNA might look inside the mineral layers. These minerals would have been common in the earliest age of Earth 2500 million years ago.

The simulations reproduced the high temperatures and pressures that occur around hydrothermal vents. It was shown that the structure of DNA inserted into layered minerals becomes stabilized at these conditions and therefore protected from catalytic and thermal degradation.

“Grids of supercomputers are essential for this kind of study”, says Professor Coveney, “The time taken to run these simulations is reduced from the years that a desktop computer would take, to hours by using the many thousands of processors made available across continents”.

Professor Coveney’s group has been researching into the routes to the origin of life for a number of years, studying the way that genetic information may have arisen and been replicated, as well as how small molecules may have formed, working together with colleagues at Nottingham and Durham Universities.

Journal reference: ‘Computer Simulation Study of the Structural Stability and Materials Properties of DNA-Intercalated Layered Double Hydroxides’ by Mary-Ann Thyveetil, Peter Coveney, H. Chris Greenwell and James Suter, is published online in the Journal of the American Chemical Society on Tuesday 18 March 2008.

 

From:http://www.sciencedaily.com/releases/2008/03/080318212430.htm

A team of chemists and physicists at the University of California, San Diego has developed a tiny, inexpensive sensor chip capable of detecting trace amounts of hydrogen peroxide, a chemical used in the most common form of homemade explosives.

 

 

Photo of penny and peroxide sensor The hydrogen peroxide sensor is the size of a penny. (Credit: UCSD)