Animation of Venus' southern polar vortex made from VIRTIS thermal infrared images; white is cooler clouds at higher altitudes.
Our neighboring planet Venus really is a world of extremes; searing surface temperatures, crushing air pressure, sulfuric acid clouds…Venus pretty much pushes the envelope on every aspect of rocky-planet existence. And now here’s one more thing that made scientists do a double-take: a shape-shifting vortex swirling around Venus’ south pole!
The presence of a cyclonic storm around Venus’ poles – both north and south – has been known since Mariner 10’s pass in 1974 and then afterwards during the Pioneer Venus mission when a downwardly-spiraling formation of clouds over the planet’s north pole was imaged in infrared. It wasn’t until ESA’s Venus Express orbiter arrived in 2006 that the cyclone at the south pole was directly observed via the Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) instrument…and it proved to be much stranger than anything previously expected. Continue reading “A Varying Venusian Vortex”
Mars volcanoes Ceraunius Tholus and Uranius Tholus, as seen by Mars Express. Credits: ESA/DLR/FU Berlin (G. Neukum). Click for larger version.
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Looking like Mars’ version of Land of the Lost, these two mist-capped volcanoes are located in the Tharsis region in Mars’ northern hemisphere. In this latest set of images released by the Mars Express team, a desolate looking landscape is softened by icy clouds drifting past the summit of Ceraunius Tholus, with the smaller Uranius Tholus to the right. No dinosaurs or Sleestaks are visible, but it looks like Uncle Jack could show up any minute!
The image was created from three different passes over the region by the spacecraft, and – surprisingly – during the middle orbit the clouds showed up. By the time Mars Express crossed again and took the final strip of data needed for this image, the clouds had long since dispersed and so there is a sharp line across them in the finished mosaic.
See below for a 3-D, perspective view of these two volcanoes.
Mars' volcanoes Ceraunius Tholus and Uranius Tholus in 3-D. Credits: ESA/DLR/FU Berlin (G. Neukum). Click for larger version.
Tharsis region — often called the Tharsis Bulge — is a continent-size volcanic plateau in Mars’ western hemisphere. The region is home to the largest volcanoes in the solar system, including the three enormous shield volcanoes Arsia Mons, Pavonis Mons, and Ascraeus Mons. The tallest volcano on the planet, Olympus Mons, is way off to the western side of the Tharsis plateau.
The ATV Johannes Kepler docked at the International Space Station. Credit: NASA
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ESA’s Automated Transfer Vehicle Johannes Kepler is more than just a cargo carrier for the International Space Station, it is also an on-orbit refueling station and orbit booster. On May 17-19, 2011 the Kepler ATV is scheduled to conduct its first refueling of the ISS, as it will transfer about 850.6 liters (225 gallons) of propellant for the station’s own thrusters for future boosts in orbit.
Preparations for the ISS refueling began on March 22 with a leak test of the propellant transfer lines, to ensure the connections between the ISS and ATV-2 were completely sealed; the test was a success, meaning that as of now, everything is go for the station’s refueling.
The Johannes Kepler ATV-2 approaches the International Space Station. Docking of the two spacecraft occurred on Feb. 24, 2011. Credit: NASA
In mid-March, the ATV increased the ISS’s orbit with a 882-second (14 and a half minutes) burn, giving the ISS an extra push of about 2.1 m/s. In all, Kepler brought nearly 10,000 pounds (4,500 kilograms) of propellant that has been used by its thrusters to boost the space station to a new altitude of 400 kilometers (248 miles) above the Earth. This will be the new “normal” for the station’s orbit. Previously, the ISS orbited about 350 km (220 miles) up.
The main benefit of raising the station’s altitude is to cut the amount of fuel needed to keep it there by more than half. This also means that visiting vehicles will not be able to carry as much cargo as they could if they were launching to the station at a lower altitude since they will need more fuel to reach the station, but it also means that not as much of that cargo needs to be propellant.
The orbit of the ISS degrades because Earth’s atmosphere — though tenuous at those altitudes – expands and contracts through the Sun’s influence, and there are enough molecules that contact the surfaces of its large solar array panels, the large truss structure, and pressurized modules to change its speed, or velocity, which is about 28,000 kilometers an hour (17,500 mph).
At the ISS’s old altitude, the space station uses about 19,000 pounds of propellant a year to maintain a consistent orbit. At the new, slightly higher altitude, the station is expected to expend about 8,000 pounds of propellant a year. And that will translate to a significant amount of food, water, clothing, research instruments and samples, and spare parts that can be flown on the cargo vehicles that will keep the station operational until 2020 and beyond.
Kepler also sent a breath of fresh air to the station by transferring about 8kg of oxygen to the ISS in March, which was the first re-pressurization of the ISS’s internal atmosphere conducted by Kepler.
A view the space station as Discovery approaches for docking. Credit: NASA
In this GOCE image, gravity is strongest in yellow areas; it is weakest in blue ones. Credit: ESA
Although they aren’t particularly fond of the comparison, scientists from the GOCE satellite team had to admit that new data showing Earth’s gravity field – or geoid — makes our planet look like a rotating potato. After just two years in orbit, ESA’s sleek and sexy GOCE satellite (Gravity Field and Steady-State Ocean Circulation Explorer) has gathered sufficient data to map Earth’s gravity with unrivalled precision. While our world certainly doesn’t look like a spinning tuber, this exaggerated view shows the most accurate model of how gravity varies across the planet.
The geoid is nothing more than how the oceans would vary if there were no other forces besides gravity acting on our planet.
“If we had an homogeneous sphere, it would be a boring sphere,” said GOCE scientist Roland Pail from Technical University in Munich, speaking at the press briefing today. “But due to rotation, you get a flattening of the Earth, and we have topography such as mountains, and irregular mass distribution in Earth’s interior. What we are showing you here, in principle, is the gravity field by any deviations due to inhomogeneous mass distributions on the Earth and the Earth’s interior.”
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While a previous gravity satellite, the Gravity Recovery And Climate Experiment (GRACE) operated for 8 years, most of the new data from GOCE was gathered in about 14 months, and provides data where there was none before.
GOCE is able to sense tiny variations in the pull of gravity over Earth, and the data is used to construct an idealized surface, which traces gravity lumps and bumps, and is the shape the oceans would take without winds, currents, Earth’s rotation and other forces.
By comparing sea level and geoid data, GOCE is revealing data on ocean currents and circulation, sea-level change, ice dynamics, said Rory Bingham, from the University of Newcastle, which helps understand heat transport and the changing climate.
But also of interest is how GOCE data reveals shifting tectonic plates in earthquakes and magma movements under volcanoes. Following the earthquakes in Japan, scientists are looking closely, as the data should reveal a three-dimensional view of what was going on inside the Earth. Even though the motion cannot be observed directly from space, earthquakes create signatures in gravity data, which could be used to understand the processes leading to these natural disasters and ultimately help to predict them.
“Even though these quakes resulted from big movements in the Earth, at the altitude of the satellite the signals are very small. But we should still seem them in the data,” said Dr. Johannes Bouman from the German Geodetic Research Institute.
GOCE in orbit. Credit: ESA
“GOCE will give us dynamic topography and circulation patterns of the oceans with unprecedented quality and resolution,” said professor Reiner Rummel, former Head of the Institute for Astronomical and Physical Geodesy at the Technische Universität München. “I am confident that these results will help improve our understanding of the dynamics of world oceans.”
“You could say that, at its early conception, GOCE was more like science fiction,” said Volker Liebig, Director of ESA’s Earth Observation Program. “GOCE has now clearly demonstrated that it is a state-of-the-art mission.”
Artist's impression of the Cygnus-X1 binary. Credit: NASA / Honeywell Max-Q Digital Group / Dana Berry
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Using the IBIS telescope onboard the European Space Agency’s INTEGRAL satellite, researchers have reported the first measurements of polarization from a black hole binary system, which comprises a black hole and a normal star orbiting around a common center of mass.
The new observations reveal that the chaotic region is threaded by magnetic fields, and represent the first time magnetic fields have been identified so close to a black hole. Most importantly, Integral shows they are highly structured magnetic fields that are forming an escape tunnel for hot matter that would otherwise plunge into the black hole within milliseconds.
Credit: ESA, courtesy of Philippe Laurent
Philippe Laurent is a researcher with the Institute for Research into the Fundamental Laws of the Universe (IRFU), of the CEA in France. He is lead author on the paper, which appears today in Science Express.
Laurent and his colleagues detected polarized gamma-ray photons coming from Cygnus X-1 (19h 58m 21.6756s +35° 12′ 05.775″), a well-known black hole X-ray binary system in the constellation Cygnus. They suggest the polarized emission is originating from a jet of relativistic particles in close proximity to the black hole.
The graph above refers to the team’s results: “whereas the low energy photons seem not to be polarized (the inset line at the left is merely flat), the higher energy ones are strongly polarized (the inset line in the right seems to be sinusoidal), and thus should related to the jet,” Laurent wrote in an email.
The authors reveal more detail through the paper: “Spectral modeling of the data reveals two emission mechanisms: The 250-400 keV data are consistent with emission dominated by Compton scattering on thermal electrons and are weakly polarized,” they write. “The second spectral component seen in the 400keV-2MeV band is by contrast strongly polarized, revealing that the MeV emission is probably related to the jet first detected in the radio band.”
Their evidence points to the black hole’s magnetic field being strong enough to tear away particles from the black hole’s gravitational clutches and funnel them outwards, creating jets of matter that shoot into space, according to an ESA press release. The particles in the jets are being drawn into spiral trajectories as they climb the magnetic field to freedom and this is affecting a property of their gamma-ray light known as polarization.
A gamma ray, like ordinary light, is a kind of wave, and the orientation of the wave is known as its polarization. When a fast particle spirals in a magnetic field it produces a kind of light, known as synchrotron emission, which displays a characteristic pattern of polarization. It is this polarization that the team have found in the gamma rays. It was a difficult observation to make.
“We had to use almost every observation Integral has ever made of Cygnus X-1 to make this detection,” says Laurent.
Amassed over seven years, these repeated observations of the black hole now total over five million seconds of observing time, the equivalent of taking a single image with an exposure time of more than two months. Laurent’s team added them all together to create just such an exposure.
“We still do not know exactly how the infalling matter is turned into the jets. There is a big debate among theoreticians; these observations will help them decide,” says Laurent.
Jets around black holes have been seen before by radio telescopes but such observations cannot see the black hole in sufficient detail to know exactly how close to the black hole the jets originate. That makes these new observations invaluable. Such polarization measurements can provide direct insights into the nature of many astrophysical processes and the researchers say that, in the future, their discovery could further our understanding of the emission mechanisms of Cygnus X-1, a model for other black-hole binaries in the universe.
Source: Science. The paper appears today, at the Science Express website.
Hubble has edged in close to the Tarantula Nebula, peering into its bright center of ionized gases, dust and still-forming stars. The Tarantula is already a go-to celestial marvel, because its hydrogen-fueled young stars shine with such intense ultraviolet light that they ionize and redden the surrounding gas — making the nebula visible without a telescope for Earth-bound observers 170,000 light-years away. The new image may make this popular beacon, in our neighboring galaxy the Large Magellanic Cloud, even more famous.
Credit: NASA, ESA
The wispy arms of the Tarantula Nebula (RA 05h 38m 38s dec -69° 05.7?) were originally thought to resemble spindly spider legs, giving the nebula its unusual name. The part of the nebula visible in the new image is criss-crossed with tendrils of dust and gas churned up by recent supernovae. These remnants include NGC 2060, visible above and to the left of the center of the image, which contains the brightest known pulsar.
The tarantula’s bite goes beyond NGC 2060. Near the edge of the nebula, outside the frame, below and to the right, lie the remains of supernova SN 1987a, the closest supernova to Earth to be observed since the invention of telescopes in the 17th century. Hubble and other telescopes have been returning to spy on this stellar explosion regularly since it blew up in 1987, and each subsequent visit shows an expanding shockwave lighting up the gas around the star, creating a pearl necklace of glowing pockets of gas around the remains of the star. SN 1987a is visible in wide field images of the nebula, such as that taken by the MPG/ESO 2.2-meter telescope.
A compact and extremely bright star cluster called RMC 136 lies above and to the left of this field of view, providing much of the radiation that powers the multi-coloured glow. Until recently, astronomers debated whether the source of the intense light was a tightly bound cluster of stars, or perhaps an unknown type of super-star thousands of times bigger than the sun. It is only in the last 20 years, with the fine detail revealed by Hubble and the latest generation of ground-based telescopes, that astronomers have been able to conclusively prove that it is, indeed, a star cluster.
But even if the Tarantula Nebula doesn’t contain this hypothetical super-star, it still hosts some extreme phenomena, making it a popular target for telescopes. Within the bright star cluster lies star RMC 136a1, which was recently found to be the heaviest ever discovered: the star’s mass when it was born was around 300 times that of the sun. This heavyweight is challenging astronomers’ theories of star formation, smashing through the upper limit they thought existed on star mass.
Hubble infrared image showing CL J1449+0856, the most distant mature cluster of galaxies found. Color data was added from ESO’s Very Large Telescope and the NAOJ’s Subaru Telescope. Credit: NASA, ESA, R. Gobat (Laboratoire AIM-Paris-Saclay, CEA/DSM-CNRS–)
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The galaxies above are among the oldest objects astronomers have ever laid eyes — er, telescopes — on, formed when the Universe was less than a quarter of its current age. In a new study out in the journal Astronomy & Astrophysics, a team of researchers has announced that they’ve used a fleet of the world’s most powerful telescopes to measure the distance from here to there.
And things look awfully familiar.
“The surprising thing is that when we look closely at this galaxy cluster it doesn’t look young — many of the galaxies have settled down and don’t resemble the usual star-forming galaxies seen in the early Universe,” said lead author Raphael Gobat of Université Paris Diderot in France.
The Very Large Telescope (VLT) at ESO's Cerro Paranal observing site in the Atacama Desert of Chile, consisting of four Unit Telescopes with main mirrors 8.2-m in diameter and four movable 1.8-m diameter Auxiliary Telescopes. The telescopes can work together, in groups of two or three, to form a giant interferometer, allowing astronomers to see details up to 25 times finer than with the individual telescopes. Credit: Iztok Boncina/ESO
Clusters of galaxies are the largest structures in the Universe that are held together by gravity. Astronomers expect these clusters to grow over time so that massive clusters would be rare in the early Universe. Although even more distant clusters have been seen, they appear to be young clusters in the process of formation, not settled mature systems.
The international team of astronomers used the powerful VIMOS and FORS2 instruments on ESO’s Very Large Telescope (VLT) to measure the distances to some of the blobs in a curious patch of very faint red objects first observed with the Spitzer space telescope. This grouping, named CL J1449+0856 for its position in the sky, had all the hallmarks of being a very remote cluster of galaxies. The results showed that we are indeed seeing a galaxy cluster as it was when the Universe was about three billion years old.
Once the team knew the distance to this very rare object, they looked carefully at the component galaxies using both Hubble and ground-based telescopes, including the VLT. They found evidence suggesting that most of the galaxies in the cluster were not forming stars, but were composed of stars that were already about one billion years old. This makes the cluster a mature object, similar in mass to the Virgo Cluster, the nearest rich galaxy cluster to the Milky Way.
Further evidence that this is a mature cluster comes from observations of X-rays coming from CL J1449+0856 made with ESA’s XMM-Newton space observatory. The cluster is giving off X-rays that must be coming from a very hot cloud of tenuous gas filling the space between the galaxies and concentrated towards the center of the cluster. This is another sign of a mature galaxy cluster, held firmly together by its own gravity, as very young clusters have not had time to trap hot gas in this way.
As Gobat concludes, “These new results support the idea that mature clusters existed when the Universe was less than one quarter of its current age. Such clusters are expected to be very rare according to current theory, and we have been very lucky to spot one. But if further observations find many more then this may mean that our understanding of the early Universe needs to be revised.”
This remarkable photo was taken by ESA astronaut Paolo Nespoli from the ISS on 16 February 2011, just minutes after ATV Johannes Kepler lifted off on board an Ariane 5 from Kourou at 22:50 UTC. It shows the rising exhaust trail of Ariane, still in its initial vertical trajectory. The trail can be seen as a thin streak framed just beneath the Station's remote manipulator arm. Credits: ESA/ NASA
Check out the spectacular launch photo (above) of the Johannes Kepler ATV streaking skyward atop an Ariane 5 rocket as captured by astronaut Paolo Nespoli from his unparalleled vantage point looking out the windows aboard the International Space Station (ISS), in orbit some 350 km above Earth.
The launch photo shows the rising exhaust trail from the rocket just minutes after blast off of the Ariane booster on Feb. 16 from the ESA rocket base in Kourou, French Guiana, South America. The rocket was still on a vertical ascent trajectory to orbit. Additional launch photos below from space and Earth.
Photo captured on 16 February 2011 from the real-time video from the Ariane 5 launcher during the flight V200 during the time of jettisoning the boosters.
The photo vividly illustrates the maturity of the European space effort since the launch base, Ariane booster rocket, Kepler payload and astronaut Nespoli all stem from Europe and are crucial to the future life of the ISS.
Ariane 5 rocket at the Launch pad at Europe's Spaceport in Kourou, French Guiana with Johannes Kepler ATV bolted on top prior to Feb. 16 blast off.
Kepler is set to dock at the ISS on Feb. 24 and an on time arrival is essential because of an impending orbital traffic jam.
Space Shuttle Discovery is due to link up with the ISS just six hous after Kepler if the orbiter launches according to schedule on Feb. 22.
Everything is nominal with Kepler’s spacecraft systems and orbital performance at this time say European Space Agency (ESA) officials, including the deployment of ATV’s four large solar wings.
Ariane 5 liftoff with Johannes Kepler ATV
The ATV, or Automated Transfer Vehicle, is a European built resupply vessel designed to transport essential cargo and provisions to the ISS. It is Europe’s contribution to stocking up the ISS.
Kepler is carrying carries more than seven metric tons of supplies and cargo for the ISS and will be used to reboost the outpost to a higher orbit during its planned four month mission.
“ATV is a truly European spacecraft. Flying it requires experts from ESA, partner agencies and industry across half a dozen countries,” said ESA’s Bob Chesson, Head of the Human Spaceflight Operations Department.
“Getting it built, into orbit and operating it in flight to docking requires a lot of hard work and dedication from hundreds of people.”
The ATV is named after Johannes Kepler (1571-1630), the German astronomer and mathematician who is best known for discovering the laws of planetary motion. NASA also named its powerful new planet hunting space telescope after Kepler, which recently discovered the first earth sized planets orbiting inside the habitable zone.
After the shuttle is forcibly retired later this year in 2011, the very survival and continued use of the ISS will be completely dependent on a steady train of cargo and payloads lofted by unmanned resupply vessels including the ATV from Europe, HTV from Japan, Progress from Russia and commercial carriers such as SpaceX and Orbital Sciences.
Photos of Ariane rockets rising exhaust trail from Feb. 16 ATV launch photographed from the ISS. Credits: ESA/ NASA
European Space Agency (ESA) astronaut Paolo Nespoli, Expedition 26 flight engineer, conducts a test run with the French/CNES neuroscientific research experiment 3D-Space (SAP) in the Columbus laboratory of the International Space Station.
Flocculent Spiral NGC 2841, in the constellation Ursa Major. Credit: NASA, ESA and Hubble
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The Flocculent Spiral NGC 2841, shown above, is known for its profusion of young, blue stars. And yet, until recently, astronomers haven’t been able to use those stars as windows into the still-mysterious phenomenon of star formation.
Hubble’s most recent wide-field camera upgrade is changing that.
The new Wide Field Camera 3 (WFC3) was installed on Hubble in May 2009 during Servicing Mission 4, and replaces the Wide Field and Planetary Camera 2. The new camera is optimized to observe in the infrared and ultraviolet wavelengths emitted by newborn stars, shown by the bright blue clumps in the lead image. Thus, it can peer behind the veil of dust that would otherwise hide those stars from view.
The image shows a lot of hot, young stars in the disc of NGC 2841, but in reality there are just a few sites of current star formation where hydrogen gas is collapsing into new stars. It is likely that these fiery youngsters destroyed the star-forming regions in which they were formed.
Image from NASA's Galaxy Evolution Explorer (GALEX), via the NASA/IPAC Extragalactic Database
NGC 2841 is about 46 million light years away in the constellation Ursa Major. It’s part of a common group of galaxies called flocculent spirals; flocculent means fluffy or wooly-looking. Rather than boasting well-defined spiral arms, these galaxies display patchy stellar distribution.
Star formation is one of the most important processes shaping the Universe; it plays a pivotal role in the evolution of galaxies and it is also in the earliest stages of star formation that planetary systems first appear. Yet there is still much that astronomers don’t understand, such as how the properties of stellar nurseries vary according to the composition and density of the gas present, and what triggers star formation in the first place. The driving force behind star formation is particularly unclear for flocculent spirals.
An international team of astronomers is using Hubble’s WFC3 to study a sample of nearby, but wildly differing, locations where stars are forming. The observational targets include both star clusters and galaxies, and star formation rates range from the baby-booming starburst galaxy Messier 82 to the much more sedate star producer NGC 2841.
Detailed credit information for the lead image: NASA, ESA and the Hubble Heritage (STScI/AURA)-ESA/Hubble Collaboration Acknowledgment: M. Crockett and S. Kaviraj (Oxford University, UK), R. O’Connell (University of Virginia), B. Whitmore (STScI) and the WFC3 Scientific Oversight Committee.
