ESA Rosetta Mission: ROSINA water vapour discovery

ESA announced the latest important discovery regarding comet 67P/Churyumov–Gerasimenko.

Rosetta spacecraft orbiting the comet has found the water vapour from its target to be significantly different to that found on Earth.

The discovery made by Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA) fuels the debate on the origin of our planet's oceans.

That's not all, ESA's Rosetta project scientist, Matt Taylor, believes that ROSINA will make more key findings for our understanding of the origin of life. "ROSINA is continuing to take measurements and will for the rest of the mission," Taylor told reporters.

"It is making and will make invaluable detections of the composition of the comets atmosphere, as well as monitoring its density."

ROSINA is a combination of two mass spectrometers and a pressure sensor. The mass spectrometers determine the composition of the comet's atmosphere and ionosphere, measure the temperature and bulk velocity of the gas and ions, and investigate reactions in which they take part.

The ROSINA pressure sensor is capable of measuring both total and ram pressure, and will be used to determine the gas density and rate of radial gas flow.

"It can detect many different kinds of molecules and get to the heart of the constituents of the ancient comet, giving us unprecedented insight into what the conditions were at the beginning of the solar system," Taylor revealed.

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No single instrument could have the capabilities required to accomplish the ROSINA science objectives, so a three-sensor approach has been adopted.

Each sensor is optimized for a part of the scientific objectives, while at the same time complementing the other sensors.

The latest results were the most anticipated, because the origin of Earth's water is still an open question.

Taylor noticed that those findings have put recent Herschel results into context and agree with results from the Giotto mission.

"It is a very important result and was of the most anticipated, if only that it was one of the first we would be able to make," he said.

In January 2014, ESA's Herschel mission discovered water vapor around dwarf planet Ceres, and in 1986, ESA's Giotto was the first spacecraft to make close up observations of a comet.

Comets in particular are unique tools for probing the early Solar System. They harbor material left over from the protoplanetary disc out of which the planets formed, and therefore should reflect the primordial composition of their places of origin.

Hubble maps temperature, water vapour on wild exoplanet

An artist's conception of exoplanet WASP-43b orbiting an orange dwarf star roughly 260 light-years from Earth. 

About twice as massive as Jupiter, WASP-43b heats up to about 3,000 degrees Fahrenheit during its closest passes by its star, a temperature hot enough to melt steel. 

Credit: NASA, ESA

A team of scientists including a University of Colorado Boulder professor used NASA's Hubble Space Telescope to make the most detailed global map yet of the glow from a giant, oddball planet orbiting another star, an object twice as massive as Jupiter and hot enough to melt steel.

The Hubble observations show that the planet, called WASP-43b, is no place to call home.

It's a world of extremes, where winds howl at the speed of sound from a 3,000-degree-Fahrenheit dayside to a pitch-black nightside when temperatures plunge to a relatively cool 1,000 degrees Fahrenheit, still hot enough to melt silver.

The map provides information about temperatures at different layers of the planet's atmosphere and traces the amount and distribution of water present.

The findings have ramifications for understanding the atmospheric dynamics and the formation of giant planets like Jupiter, said team leader Jacob Bean of the University of Chicago.

"These measurements have opened the door for a new kind of comparative planetology."

A paper on the subject was published online Oct. 9 in Science Express.

As a ball of predominately hot hydrogen gas, there are no surface features on WASP-43b like oceans or continents that can be used to track its rotation, said CU-Boulder Assistant Professor Jean-Michel Désert, second author on the new study.

Only the drastic temperature difference between the dayside and nightside can be used by remote observers to mark the passage of a day on the strange, gaseous planet, he said.

"WASP-43b is extreme in many ways," said Désert. "It's the size of Jupiter with twice its mass. Its orbit around its host star, called an orange dwarf, takes only about 19 hours – the blink of an eye compared to the 365 days it takes Earth to orbit the sun."

Désert said the study is compelling to those trying to understand planetary formation. "Basically it is like taking a planet like Jupiter into a giant laboratory, then warming it at such a high temperature that all of the atoms and molecules comprising its atmosphere are in a gas phase."

Another bizarre thing about WASP-43b is its orbit. It orbits so close to its host star it always "shows" the same hemisphere, a phenomena similar to the orbit of the moon around Earth that is known as known as "tidal locking."

Discovered in 2011, WASP-43b is 260 light-years away, too distant to be photographed, but because its orbit is observed "edge-on" to Earth, astronomers detected it by observing regular dips in the light of its parent star as the planet passed in front of it, said Désert of CU-Boulder's Department of Astrophysical and Planetary Sciences.

More information: "Thermal structure of an exoplanet atmosphere from phase-resolved emission spectroscopy," by K.B. Stevenson et al. Science, 2014. www.sciencemag.org/lookup/doi/… 1126/science.1256758

NASA TRMM: Tropical Storm losing its strength

When TRMM passed over Tropical Storm Karina on August 19, there was an isolated area of heavy rain (red) in the western quadrant where rain was falling at a rate of 2 inches/40 mm per hour. 

Credit: NASA /SSAI, Hal Pierce

Tropical Storm Karina continues to weaken in the Eastern Pacific over open waters, and NASA data shows there's not much punch left in the storm.

NASA's Tropical Rainfall Measuring Mission (TRMM) satellite can measure the rate of rainfall from its orbit in space and when it passed over Tropical Storm Karina in the Eastern Pacific it saw an isolated area of heavy rain remaining in the storm.

Tropical Storm Karina weakened during the overnight hours and by Tuesday, August 19, maximum sustained winds had decreased to near 60 mph (95 kph).

When TRMM passed overhead at 03:04 UTC (11:04 p.m. EDT, Aug. 18) on August 19, TRMM Precipitation Radar showed that there was an isolated area of heavy rain in the western quadrant where rain was falling at a rate of 2 inches/50 mm per hour.

Cloud heights in the area of the heaviest rainfall were just under 10 kilometers indicating that the uplift in the storm is weakening, as clouds reached greater heights earlier in the week.

Forecaster Berg at NOAA's National Hurricane Center (NHC) noted today "Water vapour imagery suggests that the outflow from Tropical Storm Lowell may be helping to produce southeasterly shear over Karina, and the low-level center is now exposed to the east of a small area of deep convection."

At 5 a.m. EDT on August 19, the center of Tropical Storm Karina was located near latitude 15.7 north and longitude 134.0 west, about 1,415 miles (2,275 km) east of Hilo, Hawaii. Karina is moving toward the west-southwest near 7 mph (11 kph) and is forecast to turn westward and slow down soon. The estimated minimum central pressure is 999 millibars.

Two computer models used by the NHC to forecast tropical cyclones: the Florida State Super ensemble and HWRF models, weaken Karina to a tropical depression in about 72 hours.

NASA Cassini: The geyser basin of Saturn's moon Enceladus

This view looks across the geyser basin of Saturn's moon Enceladus, along fractures spewing water vapour and ice particles into space. 

Cassini scientists have pinpointed the source locations of about 100 geysers and gained new insights into what powers them. 

Credit: NASA/JPL-Caltech/SSI

Scientists using mission data from NASA's Cassini spacecraft have identified 101 distinct geysers erupting on Saturn's icy moon Enceladus.

Their analysis suggests it is possible for liquid water to reach from the moon's underground sea all the way to its surface.

These findings, and clues to what powers the geyser eruptions, are presented in two articles published in the current online edition of the Astronomical Journal.

Over a period of almost seven years, Cassini's cameras surveyed the south polar terrain of the small moon, a unique geological basin renowned for its four prominent "tiger stripe" fractures and the geysers of tiny icy particles and water vapour first sighted there nearly 10 years ago.

The result of the survey is a map of 101 geysers, each erupting from one of the tiger stripe fractures, and the discovery that individual geysers are coincident with small hot spots.

These relationships pointed the way to the geysers' origin.

After the first sighting of the geysers in 2005, scientists suspected that repeated flexing of Enceladus by Saturn's tides as the moon orbits the planet had something to do with their behaviour.

One suggestion included the back-and-forth rubbing of opposing walls of the fractures generating frictional heat that turned ice into geyser-forming vapour and liquid.

Alternate views held that the opening and closing of the fractures allowed water vapor from below to reach the surface.

This artist's rendering shows a cross-section of the ice shell immediately beneath one of Enceladus' geyser-active fractures, illustrating the physical and thermal structure and the processes ongoing below and at the surface.

Image Credit: NASA/JPL-Caltech/Space Science Institute

Before this new study, it was not clear which process was the dominating influence.

Nor was it certain whether excess heat emitted by Enceladus was everywhere correlated with geyser activity.

To determine the surface locations of the geysers, researchers employed the same process of triangulation used historically to survey geological features on Earth, such as mountains.

When the researchers compared the geysers' locations with low-resolution maps of thermal emission, it became apparent the greatest geyser activity coincided with the greatest thermal radiation.

Comparisons between the geysers and tidal stresses revealed similar connections. However, these correlations alone were insufficient to answer the question, "What produces what?"

The answer to this mystery came from comparison of the survey results with high-resolution data collected in 2010 by Cassini's heat-sensing instruments.

Individual geysers were found to coincide with small-scale hot spots, only a few dozen feet (or tens of meters) across, which were too small to be produced by frictional heating, but the right size to be the result of condensation of vapor on the near-surface walls of the fractures.

This immediately implicated the hot spots as the signature of the geysering process.

"Once we had these results in hand, we knew right away heat was not causing the geysers, but vice versa," said Carolyn Porco, leader of the Cassini imaging team from the Space Science Institute in Boulder, Colorado, and lead author of the first paper.

"It also told us the geysers are not a near-surface phenomenon, but have much deeper roots."

Thanks to recent analysis of Cassini gravity data, the researchers concluded the only plausible source of the material forming the geysers is the sea now known to exist beneath the ice shell.

They also found that narrow pathways through the ice shell can remain open from the sea all the way to the surface, if filled with liquid water.

In the companion paper, the authors report the brightness of the plume formed by all the geysers, as seen with Cassini's high-resolution cameras, changes periodically as Enceladus orbits Saturn.

Armed with the conclusion that the opening and closing of the fractures modulates the venting, the authors compared the observations with the expected venting schedule due to tides.

They found the simplest model of tidal flexing provides a good match for the brightness variations Cassini observes, but it does not predict the time when the plume begins to brighten.

Some other important effect is present and the authors considered several in the course of their work.

More information: "Tidally Modulated Eruptions on Enceladus: Cassini ISS Observations and Models." Francis Nimmo et al. 2014, Astronomical Journal 148 46. DOI: 10.1088/0004-6256/148/3/46

NRL Scientists detect water around a hot Jupiter

This is an artist's conception of a hot Jupiter extrasolar planet orbiting a star similar to tau Boötis. 

Credit: David Aguilar, CfA, Harvard-Smithsonian Center for Astrophysics

Scientists at the Naval Research Laboratory (NRL) are part of a research team that has detected water vapour in the atmosphere of a planet outside our solar system.

The team, including scientists from California Institute of Technology (CalTech), Harvard-Smithsonian Center for Astrophysics, Pennsylvania State University, and University of Arizona, applied a sophisticated Doppler technique to the infrared to directly detect the planet and demonstrate the presence of water in its atmosphere.

The discovery is described in the March 10, 2014 issue of The Astrophysical Journal Letters.

The planet, named tau Boo b, orbits the nearby star tau Boötis and belongs to a class of exotic planets called "hot Jupiters" that are not found in our solar system.

A hot Jupiter is a massive extrasolar planet that orbits very close to its parent star. Unlike our Jupiter, which is fairly cold and has an orbital period of about 12 years, tau Boo b orbits its star every 3.3 days and is heated to extreme temperatures by its proximity to the star.

Under these conditions, water will exist as a high temperature steam.

While hot Jupiters are found to be relatively common in the Galaxy, the origin and nature of these planets remain the subject of intense research.

The research team studied data collected at the W.M. Keck Observatory in Hawaii, using the Near Infrared Echelle Spectrograph instrument.

Because a hot Jupiter is too close to its star to separate the planet's light from that of the star, the researchers adapted a Doppler technique previously used to detect low mass-ratio spectroscopic binary stars.

Application of this method to tau Boo b, however, posed a huge challenge, because the infrared radiation from the star is more than 10,000 times greater than that of the planet.

The analysis software to extract this minute planetary signal was developed by Chad Bender, a Penn State member of the team, while he was a National Research Council Associate at NRL.

By comparing the molecular signature of water to the combined light spectrum of the planet and star, the scientists were able to measure the motion of the planet as it orbits the star and establish the presence of water vapour in the planet's atmosphere.

The team also determined that the planet is six times more massive than Jupiter.

This work is ongoing, with plans to further examine the physical properties and composition of this hot Jupiter's atmosphere.

The research team is also applying this technique to search for water and other molecules in several other hot Jupiter exoplanets.

More Information: The Astrophysical Journal Letters "Near-IR Direct Detection of Water Vapor in tau Boötis b."

Keck Observatory's NIRSPEC: Water vapour detected in the atmosphere of a hot Jupiter

Simulated data showing the method used for detecting water vapor features detected around the hot Jupiter tau Boo b. 

In this example, the planetary signal has been increased in strength relative by several orders of magnitude relative to the actual signal. 

The dotted lines show the blue- and red-shifts of the planetary and stellar lines in the data, respectively, due to the orbital motion of two bodies in the system. 

Credit: Alexandra Lockwood (CalTech), Background Image David Aguilar (CFA).

California Institute of Technology (Caltech) astronomers using data gathered at the W. M. Keck Observatory have developed a new technique for planetary scientists that could provide insight into how many water planets like Earth exist within our universe.

The results have been published on February 24th by Astrophysical Letters.

Alexandra Lockwood

Scientists have detected water vapour on other planets in the past, but these detections could only take place under very specific circumstances, according to graduate student Alexandra Lockwood, the first author of the study.

"When a planet transits, or passes in orbit, in front of its host star, we can use information from this event to detect water vapour and other atmospheric compounds."

"Alternatively, if the planet is sufficiently far away from its host star, we can also learn about a planet's atmosphere by imaging it."

However, a significant portion of the population of extrasolar planets does not fit either of these criteria and there wasn't really a way to find information about the atmospheres of these planets.

Geoffrey Blake

Looking to resolve this problem, Lockwood and her advisor Geoffrey Blake, Caltech professor of cosmochemistry, planetary sciences and chemistry, were inspired by the recent detection of carbon monoxide in the extrasolar planet, 'Tau Boo b' and they wondered if they could detect water in a similar manner.

The method used to detect carbon monoxide utilized the radial velocity (RV) technique, a technique commonly used in the visible region of the spectrum, to which our eyes are sensitive, for discovering non-transiting exoplanets.

Using the Doppler effect, RV detection traditionally determines the motion of a star due to the gravitational pull of a companion planet; the star moves opposite that of the orbital motion of the planet, and stellar features shift in wavelength. A large planet or a planet closer to its host star provides a larger shift.

An artistic impression of extrasolar planet, 'Tau Boo b' 

The team used the carbon monoxide study as a guide to expand the RV technique into the infrared to determine the orbit of extrasolar planet, 'Tau Boo b' around its star, and added further analysis of the light shifts via spectroscopy, an analysis of the light's spectrum.

Since every molecule emits a different wavelength of light, this unique light signature allows the researchers to analyze molecules that comprise the planet's atmosphere.

Using data of extrasolar planet, 'Tau Boo b' collected with the Near Infrared Echelle Spectrograph (NIRSPEC) instrument at the W. M. Keck Observatory in Hawai'i, the researchers were able to compare the molecular signature of water to the light spectrum emitted by the planet, confirming that the atmosphere did indeed include water vapour.

"The readout we get from Keck Observatory's NIRSPEC is like listening to an orchestra performance; you hear all of the music together, but if you listen carefully, you can pick out a trumpet or a violin or a cello, and you know that those instruments are present," Lockwood said.

"The instrument allows you to pick out different pieces; like this wavelength of light means that there is sodium, or this one means that there's water."

More information: "Near-IR Direct Detection of Water Vapour in Tau Boo b." Alexandra C. Lockwood, John A. Johnson, Chad F. Bender, John S. Carr, Travis Barman, Alexander J.W. Richert, Geoffrey A. Blake. arXiv:1402.0846 [astro-ph.EP].

ESA Herschel: Star Cloud Contains Enough water vapour to fill 2,000 Earth oceans

The discovery marks the first time scientists have detected water vapour in a “pre-stellar core”—the cold, dark clouds of gas and dust from which stars form.

“To produce that amount of vapor, there must be a lot of water ice in the cloud, more than three million frozen Earth oceans’ worth,” says Paola Caselli, a professor at the University of Leeds and the lead author of the paper published in Astrophysical Journal Letters.

Read the original study here

The discovery was made using the European Space Agency’s Herschel Space Observatory, in a pre-stellar core known as Lynds 1544, in the constellation of Taurus.

Water has previously been detected outside of our Solar System as gas and ice coated onto tiny dust grains near sites of active star formation, and in proto-planetary discs capable of forming planetary systems.

More than 2,000 Earth oceans-worth of water vapour were detected, liberated from icy dust grains by high-energy cosmic rays passing through the cloud.

“Before our observations, the understanding was that all the water was frozen onto dust grains because it was too cold to be in the gas phase and so we could not measure it.

“Now we will need to review our understanding of the chemical processes in this dense region and, in particular, the importance of cosmic rays to maintain some amount of water vapour.”

The research also revealed that water molecules are flowing towards the heart of the cloud where a new star is likely to form, indicating that gravitational collapse has just started.

“There is absolutely no sign of stars in this dark cloud today, but by looking at the water molecules, we can see evidence of motion inside the region that can be understood as collapse of the whole cloud towards the center,” says Caselli.

“There is enough material to form a star at least as massive as our Sun, which means it could also be forming a planetary system, possibly one like ours.”

Some of the water vapour detected in L1544 will go into forming the star, but the rest will be incorporated into the surrounding disc, providing a rich water reservoir to feed potential new planets.

“Thanks to Herschel, we can now follow the ‘water trail’ from a molecular cloud in the interstellar medium, through the star formation process, to a planet like Earth where water is a crucial ingredient for life,” says ESA’s Herschel project scientist, Göran Pilbratt.