NASA's NuStar: The 'black hole hunter' heads to the skies

A NASA illustration of NuSTAR, a sophisticated orbiting telescope that uses high-energy X-rays to hunt for black holes, poised to launch on June 13, 2012.

A sophisticated orbiting telescope that uses high-energy X-ray vision to hunt for black holes in the universe took off Wednesday in the first part of a two stage jet-to-rocket launch, NASA said.

The Nuclear Spectroscopic Telescope Array (NuSTAR) was carried into the skies Orbital Sciences' L-1011 aircraft, carrying a rocket on its underbelly that will launch the satellite from the air at 12:00 pm (1600 GMT), NASA said.

"Plane-assisted launches are less expensive than those that take place from the ground. Less fuel is needed to boost cargo away from the pull of Earth's gravity," the US space agency said in a statement.

The project aims to study energetic phenomena such as black holes and the explosions of massive stars.

Orbital Sciences Corporation designed and manufactured the telescope and will send it into orbit from its own Pegasus air-launched rocket, which is attached to the underside of the company's L-1011 Stargazer aircraft.

The jet took off from Kwajalein Atoll in the Marshall Islands.

The aircraft is scheduled to drop the Pegasus rocket 117 nautical miles south of Kwajalein, at an altitude of 39,000 feet over the Pacific Ocean, quite close to the equator.

The spacecraft should separate from the rocket 13 minutes later.

"NuSTAR will open a whole new window on the universe," said Fiona Harrison, who is a professor at the California Institute of Technology in Pasadena and is the principal investigator on NuSTAR.

It will be the "first telescope to focus high energy X-rays. As such it will make images that are 10 times crisper and 100 times more sensitive than any telescope that has operated in this region of the spectrum."

The mission aims to work in concert with other telescopes in space, including NASA's Chandra X-ray Observatory, which observes lower-energy X-rays, NASA said.

NuSTAR is more potent than its predecessors because of the way it focuses high-energy X-ray light by using nested shells of mirrors to prevent the light from reflecting off.

With 133 nested mirrors in each of two optical units, the telescope also uses state-of-the-art detectors and a long mast that connects the optical units to the detectors and allows enough distance for a sharp focus.

The 33-foot (10-meter) mast will launch in a folded-up position but will extend about a week after launch, bringing it to about the length of a school bus.

"It used to be thought that black holes were rare and exotic -- that was just 20 years ago," Harrison told reporters.

"Today we know that every massive galaxy, like our Milky Way, has a massive black hole at its heart."

The new observatory aims to give a better view of the workings of a black hole, since the dust and gas that gets sucked into the gravity of a black hole becomes quite hot from speed and friction created as it circulates around the edge.

Paul Hertz, NASA's Astrophysics Division director, described NuSTAR as "a small space telescope that will provide world-class science in an important but relatively unexplored band of the electromagnetic spectrum."

New German scope will study the Sun

One of the major centres for solar studies is on the holiday island of Tenerife, high on the Moon-like landscape of the plateau surrounding Mount Teide called Las Canadas.

I remember this already being an important observatory with way back in the early Seventies when I was a young site-tester on the plateau checking sky conditions for another planned observatory that ended up being built on the neighbouring island of La Palma.

Now a new German solar telescope has been added to the mushrooming number of solar instruments at the site, called the Spanish Observatorio del Teide of the Instituto de Astrofísica de Canarias at Izaña. Called GREGOR, it is the largest solar telescope in Europe and the third biggest in the world.

This telescope, which will be inaugurated on May 21, is unusual because it will also be used at night to observe bright stars and compare their cycle of activity changes with the Sun.

GREGOR has a mirror 1.5 metres across (5ft) and will observe the Sun’s visible surface, called the photosphere, and the lower region of its atmosphere called the chromosphere, in the visible and infrared regions of the spectrum.

A range of instruments in neighbouring laboratory rooms will examine the light to study how these solar regions interact with the Sun’s magnetic field and movement of hot plasma.

Like many telescopes nowadays, a system of adaptive optics will compensate for atmospheric disturbances. Together with the large diameter this will allow observation of the Sun in great detail, down to features just 70km across, which the German team claim will be similar to what can be achieved in space.

Another unusual aspect of GREGOR is that it will operate in the open rather than a dome to allow the wind to cool the telescope’s structure and its mirrors. Its protective housing slides away to allow this.

The main mirror, or primary, is relatively lightweight and made from a material that does not change its shape under the heat of the brilliant Sun. It is also has a cooling mechanism added to the back of the primary to prevent it from heating up and producing image-distorting turbulence.

GREGOR, which will be open to use by astronomers from all over the world, was built by a German consortium led by the Kiepenheuer-Institut für Sonnenphysik in Freiburg with partners the Leibniz-Institut für Astrophysik Potsdam and the Max-Planck-Institut für Sonnensystemforschung in Katlenburg/Lindau.

Other contributions were made by the Instituto de Astrofísica de Canarias, the Institut für Astrophysik Göttingen, and the Astronomical Institute of the Academy of Sciences of the Czech Republic.

Plastic Space Telescopes: Photon sieves make super-cheap viewers

FLEXIBLE plastic telescopes launched from microsatellites could serve as quick replacements for space observatories taken out by solar flares, or spy satellites downed by military action.

The telescopes, which are being developed by Geoff Andersen and colleagues at the US Air Force Academy in Colorado Springs, rely on an imaging device called a photon sieve. 

Traditional telescopes use lenses or mirrors to focus light by refraction or reflection, but the photon sieve uses diffraction instead. 

The sieve is an ultra-thin plastic disc perforated by millions of microscopic holes, each of which bends light at different angles to create a focal point.

Less light reaches the focal point compared with traditional lenses or mirrors, making it hard to image dim objects, and the device can only take black-and-white pictures. 

But the sieve is cheap, lightweight and easy to manufacture at large sizes. It can also be tightly folded and unfurled without being damaged. "You can't do that with mirrors or lenses," says Andersen, who hopes to launch a device into orbit in 2014.

The planned 20-centimetre-diameter telescope will be scrunched up inside a CubeSat, a microsatellite just 10 × 10 × 30 cm, designed for cheaply carrying small payloads. 

Andersen's team aims to take pictures of the sun to prove that the concept works. A similar device could also help the search for Earth-like planets, Andersen says, though such images would require a big telescope, and would likely be just a few pixels wide.

The US Defense Advanced Research Projects Agency is also interested in using the concept to build a 20-metre version of the photon sieve for imaging objects on the ground at sub-metre resolutions.

Andersen says the design is partly a response to China's demonstration in 2007 of an anti-satellite missile. "That showed a billion-dollar national asset could be shot down at any time," he says.

He will present the research at the Defense, Security and Sensing conference in Baltimore, Maryland, next month.

Marek Kukula of the Royal Observatory Greenwich in London says that while the devices won't replace the likes of the Hubble or James Webb space telescopes, a "cheap and cheerful" alternative to smaller telescopes would have many applications.

Explosive Stars with Good Table Manners

These images from Swift's Ultraviolet/Optical Telescope (UVOT) show the nearby spiral galaxy M101 before and after the appearance of SN 2011fe (circled, right), which was discovered on Aug. 24, 2011.

At a distance of 21 million light-years, it was the nearest Type Ia supernova since 1986. Left: View constructed from images taken in March and April 2007.

Right: The supernova was so bright that most UVOT exposures were short, so this view includes imagery from August through November 2011 to better show the galaxy.

Credit: NASA/Swift/Peter Brown, Univ. of Utah.

An exploding star known as a Type Ia supernova plays a key role in our understanding of the universe. Studies of Type Ia supernovae led to the discovery of dark energy, which garnered the 2011 Nobel Prize in Physics. Yet the cause of this variety of exploding star remains elusive.

All evidence points to a white dwarf that feeds off its companions star, gaining mass, growing unstable, and ultimately detonating. But does that white dwarf draw material from a Sun-like star, an evolved red giant star, or from a second white dwarf? Or is something more exotic going on? Clues can be collected by searching for "cosmic crumbs" left over from the white dwarf's last meal.

In two comprehensive studies of SN 2011fe - the closest Type Ia supernova in the past two decades - there is new evidence that indicates that the white dwarf progenitor was a particularly picky eater, leading scientists to conclude that the companion star was not likely to be a Sun-like star or an evolved giant.

"It's hard to understand how a white dwarf could eat itself to death while showing such good table manners," said Alicia Soderberg of the Harvard-Smithsonian Center for Astrophysics (CfA).

Soderberg and her colleagues examined SN 2011fe with a suite of instruments in wavelengths ranging from X-rays to radio.

They saw no sign of stellar material recently devoured by the white dwarf. Instead, the explosion occurred in a remarkably clean environment.

"This white dwarf was a tidy eater," said Laura Chomiuk of the CfA, lead author of one of the two papers.

Additional studies using NASA's Swift satellite, which examined a large number of more distant Type Ia supernovae, appear to rule out giant stars as companions for the white-dwarf progenitors. Those results were described in a NASA press release.

Taken together, these studies suggest that Type Ia supernovae likely originate from a more exotic scenario, possibly the explosive merger of two white dwarfs.

"This is an exciting time in Type Ia supernova research since it brings us closer to solving one of the longest-standing mysteries in the life cycles of stars," said Raffaella Margutti of the CfA, lead author of the second paper.

NASA UARS: Debris may never be recovered

A six-ton NASA science satellite crashed to Earth on Saturday, leaving a mystery about where a ton of space debris may have landed.

The U.S. space agency said it believes the debris ended up in the Pacific Ocean, but the precise time of the bus-sized satellite's re-entry and the location of its debris field have not been determined.

The Upper Atmosphere Research Satellite, or UARS, ended 20 years in orbit with a suicidal plunge into the atmosphere sometime between 11:23 p.m. on Friday and 1:09 a.m. EDT on Saturday (0323 to 0509 GMT Saturday), NASA said.

The satellite would have been torn apart during the fiery re-entry, but about 26 pieces, the largest of which was estimated to have weighed 330 pounds (150 kg), likely survived the fall, officials said.

As it fell to Earth, UARS passed from the east coast of Africa over the Indian Ocean, then the Pacific Ocean, across northern Canada and the northern Atlantic Ocean to a point over West Africa. Most of the transit was over water, with some flight over northern Canada and West Africa, NASA said.

"Because we don't know where the re-entry point actually was, we don't know where the debris field might be," said Nicholas Johnson, chief orbital debris scientist at NASA's Johnson Space Center in Houston. "We may never know."

Stretching 35 feet long and 15 feet in diameter, UARS was among the largest spacecraft to plummet uncontrollably through the atmosphere, although it is a slim cousin to NASA's 75-tonne (68,000 kilogram) Skylab station, which crashed to Earth in 1979.

Russia's last space station, the 135-tonne (122,000 kilogram) Mir, crashed into the Pacific Ocean in 2001, but it was a guided descent.

NASA now plans for the controlled re-entry of large spacecraft, but it did not when UARS was designed.

The 13,000-pound (5,897 kg) satellite was dispatched into orbit by a space shuttle crew in 1991 to study ozone and other chemicals in Earth's atmosphere.

It completed its mission in 2005 and has been slowly losing altitude ever since.

With most of the planet covered in water and vast uninhabited deserts and other land directly beneath the satellite's flight path, the chance that someone would be hit by falling debris was 1-in-3,200, NASA said.
"The risk to public safety is very remote," it said.

The satellite flew over most of the planet, traveling between 57 degrees north and 57 degrees south of the equator.

UARS was one of about 20,000 pieces of space debris in orbit around Earth. Something the size of UARS falls back into the atmosphere about once a year.

Saturn-lookalike galaxy has a mysterious pastNew Scientist

Centuries before telescopes revealed galaxies to us, philosopher Immanuel Kant suggested that "island universes" – agglomerations of stars and gas – existed.

It's a fitting description for the peculiar galaxy pictured right. Consisting of a bright yellow spherical core surrounded by a symmetrical luminous ring of blue-tinged stars, Hoag's object looks like it's doing an impression of the planet Saturn.

This is unlike any other galaxy – and so perplexing to astronomers that it might as well exist in another universe.

"It's one of these weird little objects you point at without fully understanding what they mean," explains François Schweizer of the Carnegie Observatories in Pasadena, California.

He has done his bit in a 60-year struggle to pin down the forces and events that might have created the enigmatic galaxy. Recent observations suggest the core came first and the ring added in later – but the details are still puzzling.

Funhouse mirror
Galaxies come in a variety of shapes, but most fit into one of just a few categories – simple spheroids or ellipses, flattened discs, elegant spirals like the Milky Way or irregularly shaped blobs. But Hoag's object is so bizarre that when astronomer Arthur Hoag first spotted it in 1950, he wasn't even sure it was a galaxy.

Instead he thought it might be a ring-shaped puff of gas given off by a dying star: a type of object called a planetary nebula that is commonly found in the Milky Way. But Hoag himself was unsatisfied with that explanation, noting that the ring was not emitting light at the wavelengths characteristic of the hot gas in such clouds.

He further speculated that the ring could be an optical illusion, the result of a phenomenon called gravitational lensing, in which a foreground galaxy's gravity bends the light of a more distant galaxy, giving it a peculiar shape – like looking at it in a funhouse mirror.

But that explanation failed, too. In 1974, observations of the core of Hoag's object showed it weighs far too little to cause the extreme gravitational lensing needed to turn a background galaxy into a ring.

NASA Kepler: 'Invisible' planet discovered with new technique

The "invisible" world Kepler-19c, seen in the foreground of this artist's conception, was discovered solely through its gravitational influence on the companion world Kepler-19b — the dot crossing the star's face.

Kepler-19b is slightly more than twice the diameter of Earth, and is probably a "mini-Neptune." Nothing is known about Kepler-19c other than that it exists.

For the first time, scientists have definitively discovered an "invisible" alien planet by noticing how its gravity affects the orbit of a neighbouring world, a new study reports.

NASA's Kepler space telescope detected both alien planets, which are known as Kepler-19b and Kepler-19c.

Kepler spotted 19b as it passed in front of, or transited, its host star. Researchers then inferred the existence of 19c after observing that 19b's transits periodically came a little later or earlier than expected. The gravity of 19c tugs on 19b, changing its orbit.

The discovery of Kepler-19c marks the first time this method — known as transit timing variation, or TTV — has robustly found an exoplanet, researchers said. But it almost certainly won't be the last.

"My expectation is that this method will be applied dozens of times, if not more, for other candidates in the Kepler mission," said study lead author Sarah Ballard of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass.

Finding two new planets
The Kepler spacecraft launched in March 2009. It typically hunts for alien worlds by measuring the telltale dips in a star's brightness caused when a planet crosses the star's face from the telescope's perspective, blocking some of its light.

Kepler has been incredibly successful using this so-called transit method, spotting 1,235 candidate alien planets in its first four months of operation. That's the way it detected Kepler-19b, a world 650 light-years away from Earth in the constellation Lyra.

Kepler-19b has a diameter about 2.2 times that of Earth, researchers said, and orbits 8.4 million miles (13.5 million kilometers) from its parent star. The planet likely has a surface temperature around 900 degrees Fahrenheit (482 degrees Celsius).

Kepler-19b transits its host star once every nine days and seven hours. But that number isn't constant, Ballard and her team found; transits can occur up to five minutes early or five minutes late. That variation told them another planet was tugging on 19b, alternately speeding it up and slowing it down.

In our own solar system, scientists used similar methods to predict the existence of the planet Neptune. Astronomers noticed that Uranus did not orbit the sun exactly as expected, and surmised that an unseen planet was pulling on it. This prediction was borne out when telescopes confirmed Neptune's existence in 1846.

Researchers know little about Kepler-19c at the moment. It takes the alien world 160 days or less to zip around its host star, and 19c's mass could range from a few times that of Earth to six times that of Jupiter, researchers said.

But 19c should start coming into clearer focus soon.

"It's a mystery world, but of course we don't expect it to remain a mystery," study co-author David Charbonneau, also of the Harvard-Smithsonian Center for Astrophysics, told Space.com in an email. "Kepler, and large ground-based telescopes, should help us figure out its true identity soon enough!"

The study will be published in The Astrophysical Journal.

SOFIA Airborne telescope: Makes its first observations - New Scientist

Airborne telescope makes its first observations - space - 28 May 2010 - New Scientist

SOFIA snapped this composite infrared image of Jupiter (right) during its first flight as a working observatory. The white stripe shows a region of relatively transparent clouds that reveal the planet's warm interior (Image: NASA)

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A jet with a large telescope built into its side has snapped its first in-flight images of the night sky. The flight begins a new phase for the infrared observatory, called SOFIA, which was once in danger of cancellation due to cost overruns.

The Stratospheric Observatory for Infrared Astronomy (SOFIA) is a Boeing 747 jet that has been modified to carry a 2.5-metre telescope provided by the German Space Agency. The observatory is designed to fly at an altitude of about 12 kilometres.

That altitude is above more than 99 per cent of the atmosphere's water vapour, which obscures the sky at infrared wavelengths. That means SOFIA will receive roughly 80 per cent of the infrared light that hits orbiting space telescopes. It can be used to study phenomena such as star and planet formation in the Milky Way.

The telescope took off on Wednesday from NASA's Dryden Flight Research Center in Palmdale, California, for its first in-flight night observations. Images taken during the six-hour flight are sharp enough for the telescope to perform "front-line astronomical research", SOFIA project scientist Pam Marcum said in a statement.

SOFIA, which cost more than $1 billion to develop, was nearly cancelled due to delays and cost overruns. NASA decided to restore funding to the project in 2006, after criticism from astronomers and a technical review that said the project faced no insurmountable challenges.

NASA aims to fly SOFIA several times a week for about 20 years.