Cassini Testing Part of Its Radio System

NASA / ESA - Cassini Mission to Saturn logo.

Jan. 14, 2012

Cassini Mission Status Report

Engineers with NASA's Cassini mission are conducting diagnostic testing on a part of the spacecraft's radio system after its signal was not detected on Earth during a tracking pass in late December. The spacecraft has been communicating with Earth using a backup part.

The issue occurred with the ultra-stable oscillator, which is used for one type of radio science experiment and also as a means of sending data back to Earth. The spacecraft is currently using an auxiliary oscillator, whose frequency stability is adequate for transmitting data from the spacecraft to Earth. Tests later this month will help mission managers decide whether it will be possible to bring the ultra-stable oscillator back into service.

Artist concept of Cassini at Saturn

Some of the data collected for the radio science experiment using the auxiliary oscillator will be of lesser quality than that from the ultra-stable oscillator. Signals used for occultation experiments – where scientists analyze how radio signals are affected as they travel through Saturn's rings or the atmospheres of Saturn and its moons back to Earth – will be of lesser quality. A second kind of radio science investigation using gravity measurements to probe the internal structure of Saturn or its moons will not be affected. Cassini carries 12 science experiments.

The cause is still under investigation, but age may be a factor. The spacecraft launched in 1997 and has orbited Saturn since 2004. Cassini completed its prime mission in 2008 and has had two additional mission extensions. This is the first time its ultra-stable oscillator has had an issue.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. NASA's Jet Propulsion Laboratory in Pasadena manages the mission for the agency's Science Mission Directorate in Washington.

Welcome Disruption

The line of Saturn's rings disrupts the Cassini spacecraft's view of the moons Tethys and Titan

Larger Titan (3,200 miles, or 5,150 kilometers across) is on the left. Tethys (660 miles, or 1,062 kilometers across) is near the center of the image. This view looks toward the Saturn-facing sides of Tethys and Titan. The angle also shows the northern, sunlit side of the rings from less than one degree above the ring plane. The image was taken in visible red light with the Cassini spacecraft narrow-angle camera on Dec. 7, 2011. The view was acquired at a distance of approximately 1.4 million miles (2.2 million kilometers) from Tethys and 1.9 million miles (3.1 million kilometers) from Titan. Image scale is 8 miles (13 kilometers) per pixel on Tethys and 12 miles (19 kilometers) on Titan.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two on-board cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo.

For more information about the mission, visit: http://www.nasa.gov/cassini and http://saturn.jpl.nasa.gov

Images, Text, Credit: NASA / JPL-Caltech / Space Science Institute.

Best regards, Orbiter.ch

Spacecraft Completes Biggest Maneuver

NASA - Mars Science Laboratory (MSL) patch.

Jan. 12, 2012

Mission Status Report

NASA's Mars Science Laboratory spacecraft successfully refined its flight path Wednesday with the biggest maneuver planned for the mission's journey between Earth and Mars.

"We've completed a big step toward our encounter with Mars," said Brian Portock of NASA's Jet Propulsion Laboratory, Pasadena, Calif., deputy mission manager for the cruise phase of the mission. "The telemetry from the spacecraft and the Doppler data show that the maneuver was completed as planned."

The Mars Science Laboratory mission will use its car-size rover, Curiosity, to investigate whether the selected region on Mars inside Gale Crater has offered environmental conditions favorable for supporting microbial life and favorable for preserving clues about whether life existed.

Engineers had planned today's three-hour series of thruster-engine firings to accomplish two aims: to put the spacecraft's trajectory about 25,000 miles (about 40,000 kilometers) closer to encountering Mars and to advance the time of the encounter by about 14 hours, compared with the trajectory following the mission's Nov. 26, 2011, launch.

Artist's concept illustrations show (left) the Mars Science Laboratory spacecraft during its voyage from Earth to Mars and (right) the mission's rover, Curiosity, working on Mars after landing. Image credit: NASA / JPL-Caltech.

"The timing of the encounter is important for arriving at Mars just when the planet's rotation puts Gale Crater in the right place," said JPL's Tomas Martin-Mur, chief navigator for the mission.

The mission's second trajectory correction maneuver, expected to be about one-sixth the magnitude of this first one, is scheduled for March 26. Up to four additional opportunities for fine-tuning, as needed, are scheduled before the arrival at Mars on Aug. 5, 2012, PDT (Aug. 6, EDT and Universal Time).

The spacecraft's initial trajectory resulting from the launch included an intentional offset to prevent the upper stage of the launch vehicle from hitting Mars. That upper stage was not cleaned the way the spacecraft itself was to protect Mars from Earth's microbes.

The Mars Science Laboratory spacecraft rotates in flight at about two revolutions per minute. Today's maneuver included two different components: one that changed velocity in the direction of the axis of the spacecraft's rotation, and one that changed velocity in a direction perpendicular to that.

The maneuver used the eight thruster engines on the cruise stage of the spacecraft, grouped into two sets of four. It began with a thrust lasting about 19 minutes, using just one thruster in each set and affecting velocity along the direction of the axis of rotation. Then, to affect velocity perpendicular to that line, each set of thrusters was fired for 5 seconds when the rotation put that set facing the proper direction. These 5-second bursts were repeated more than 200 times during a period of about two hours for a total of about 40 minutes.

Mars Science Laboratory Curiosity Rover Animation

The maneuver was calculated to produce a net change in velocity of about 12.3 miles per hour (5.5 meters per second), combining a slight increase in speed with a small change in direction of travel.

As of 9 a.m. PST (noon EST) on Thursday, Jan. 12, the spacecraft will have traveled 81.2 million miles (130.6 million kilometers) of its 352-million-mile (567-million-kilometer) flight to Mars. It will be moving at about 10,300 mph (16,600 kilometers per hour) relative to Earth, and at about 68,700 mph (110,500 kilometers per hour) relative to the sun.

JPL, a division of the California Institute of Technology in Pasadena, manages the Mars Science Laboratory mission for the NASA Science Mission Directorate, Washington.

More information about Curiosity is online at: http://www.nasa.gov/msl and at http://mars.jpl.nasa.gov/msl

You can follow the mission on Twitter at http://www.twitter.com/marscuriosity and on Facebook at: http://www.facebook.com/marscuriosity

Images (mentioned), Video, Text, Credit: NASA / JPL / Guy Webster.

Greetings, Orbiter.ch

ESA coordinates international satellite reentry campaign

ESA / ESOC logo.

12 January 2012

An international campaign to assess the imminent atmospheric reentry of Russia's Phobos–Grunt Mars craft is being coordinated by experts in ESA's Space Debris Office. Participants include NASA and Roscosmos as part of the 12-member Inter-Agency Space Debris Coordination Committee.

ESA experts are working with international partners in a coordinated prediction campaign focused on Phobos–Grunt, a Russian Mars mission that is expected to largely burn up in Earth's atmosphere in the next few days.

Phobos-Grunt orbiter and lander

Phobos–Grunt was launched on 8 November 2011 into an initial Earth orbit of 206 x 341 km. The injection into an Earth-escape trajectory to Mars failed, and the spacecraft was declared lost by the Russian space agency, Roscosmos, on 13 December.

On 2 January, a comprehensive reentry prediction campaign for Phobos–Grunt was begun by the Inter-Agency Space Debris Coordination Committee (IADC), a technical forum for the worldwide coordination of activities related to human-made and natural debris in space. 

ESOC in Darmstadt hosts reentry database

ESA's Space Debris Office, located at ESOC, the European Space Operations Centre, Darmstadt, Germany, hosts the IADC reentry event database that is used to exchange orbit data and reentry predictions among IADC members.

ESA / ESOC - Main Control Room

Orbit data for Phobos–Grunt are provided mainly by the US Space Surveillance Network and the Russian Space Surveillance System. Based on this, ESA is issuing reentry prediction bulletins to its Members States.

According to its Russian owners, Phobos–Grunt has a mass of 13.5 tonnes, including about 11 tonnes of propellant, and a body size of 3.76 x 3.76 x 6.38 m, with solar wings spanning 7.97 m.

Large number of uncertainties affect reentry

"Right now, due to the large number of uncertainties in the orbit and space environment affecting the satellite, the indications are that Phobos-Grunt could reenter between 13 and 17 January, between 51.4°N and 51.4°S," says Prof. Heiner Klinkrad, Head of ESA's Space Debris Office.

He adds that this window will shorten as we approach reentry.

"Analyses by Roscosmos and NASA indicate that the fuel tanks, filled with unsymmetrical dimethylhydrazine – referred to as UDMH – will burst above 100 km altitude, release the propellant and largely demise thereafter."

H. Klinkrad

"This, combined with a relatively low dry mass of just 2.5 tonnes, means that Phobos–Grunt is not considered to be a high-risk reentry object."

"Roscosmos expects that at most, some 20 to 30 fragments may reach Earth's surface, with a total mass of less than 200 kg."

Since the beginning of the space age, there has been no confirmed report of an injury resulting from reentering space objects.

IADC assesses potentially hazardous reentries

In recent years, IADC members have developed a data exchange network specifically supporting the assessment of potentially hazardous reentries, which allows members to enter and extract orbit data in order to refine reentry predictions.

IADC member agencies include ESA, NASA, European national agencies and the Russian, Chinese, Canadian, Japanese, Ukrainian and Indian space agencies.

Results from the Phobos–Grunt reentry campaign will be used by IADC members to improve reentry models and make future predictions more accurate.

Enhancing Europe's observation capacity

In 2009, ESA launched the Space Situational Awareness Preparatory Programme, which, in part, aims to design a network of surveillance and tracking systems and novel data processing technologies that will enable Europe to build up a complete catalogue of orbiting objects.

This system will provide highly accurate data to reduce the threat from on-orbit collisions and improve predictions of where and when uncontrolled satellite re-entries could occur.

More information:

Phobos-Soil mission: http://sci.esa.int/science-e/www/area/index.cfm?fareaid=122

Inter-Agency Space Debris Coordination Committee (IADC): http://www.iadc-online.org/

Roscosmos: http://www.roscosmos.ru/main.php?lang=en

NPO Lavochkin: http://www.laspace.ru/rus/index.php

Space Debris: http://www.esa.int/SPECIALS/Space_Debris/index.html

Space Situational Awareness: http://www.esa.int/SPECIALS/SSA/index.html

Images, Text, Credits: ESA / P. Shlyaev / J. Mai / Lavochkin Association.

Greetings, Orbiter.ch

Rare Ultra-blue Stars Found in Neighboring Galaxy's Hub

ESA - Hubble Space Telescope logo.

Jan. 11, 2012

Peering deep inside the hub of the neighboring Andromeda galaxy, NASA's Hubble Space Telescope has uncovered a large, rare population of hot, bright stars.

The image at left shows the nearby, majestic Andromeda galaxy. The rectangular box marks the region probed by NASA’s Hubble Space Telescope (a blend of visible and ultraviolet light). The photo (top right) is 7,900 light-years across and reveals the galaxy's crowded central region. The bright area near the center of the image is a grouping of stars nestled around the galaxy's black hole. The blue dots sprinkled throughout the image are ultra-blue stars whose population increases around the crowded hub. The square box shows a close-up view of an area around the core. The detailed image, shown at bottom right, reveals a richer population of blue stars huddled around the core. Dark dust clouds also are visible. The right-hand images, taken with Hubble, are part of a census of stars in M31 called the Panchromatic Hubble Andromeda Treasury survey. (Credit: NASA; ESA; B. Williams and J. Dalcanton, University of Washington, Seattle).

Blue is typically an indicator of hot, young stars. In this case, however, the stellar oddities are aging, sun-like stars that have prematurely cast off their outer layers of material, exposing their extremely blue-hot cores.

Astronomers were surprised when they spotted these stars because physical models show that only an unusual type of old star can be as hot and as bright in ultraviolet light.

While Hubble has spied these ultra-blue stars before in Andromeda, the new observation covers a much broader area, revealing that these stellar misfits are scattered throughout the galaxy's bustling center. Astronomers used Hubble's Wide Field Camera 3 to find roughly 8,000 of the ultra-blue stars in a stellar census made in ultraviolet light, which traces the glow of the hottest stars. The study is part of the multi-year Panchromatic Hubble Andromeda Treasury survey to map stellar populations across the galaxy.

"We were not looking for these stars. They stood out because they were bright in ultraviolet light and very different from the stars we expected to see," said Julianne Dalcanton of the University of Washington in Seattle, leader of the Hubble survey.

The team's results are being presented today at the American Astronomical Society meeting in Austin, Texas. A paper describing the finding will be published in The Astrophysical Journal.

The telescope spied the stars within 2,600 light-years of the core. After analyzing the stars for nearly a year, Dalcanton's team determined that they were well past their prime. "The stars are dimmer and have a range of surface temperatures different from the extremely bright stars we see in the star-forming regions of Andromeda," said Phil Rosenfield of the University of Washington, the paper's lead author.

As these stars evolved, puffing up to become red giants, they ejected most of their outer layers to expose their blue-hot cores. When normal sun-like stars swell up to become red giants, they lose much less material and therefore never look as bright in the ultraviolet.

"We caught these stars when they're the brightest, just before they become white dwarfs," said team member Leo Girardi of the National Institute for Astrophysics's Astronomical Observatory of Padua. "It is likely that there are many other similarly hot stars in this central part of Andromeda at earlier stages of their lives. But such stars are too dim for Hubble to see because they're mixed in with a crowd of normal stars."

The astronomers have proposed two possible scenarios to explain why these blue stars evolve differently. According to Rosenfield, the most likely scenario is that the stars are rich in chemical elements other than hydrogen and helium. Observations with ground-based telescopes have shown the stars in the galaxy's hub have an abundant supply of "heavy elements," which makes it easier for stars to eject lots of material into space late in life.

Andromeda Galaxy's Double Nucleus

This zoom (video) dives deep into the nucleus of the neighboring spiral galaxy M31, also known as the Andromeda galaxy.

In this scenario radiation from the star is more efficient at pushing on gas laced with heavy elements, which drives away the material, like wind moving a thick sail. Although all the stars in the core are enriched in heavy elements, the bright blue stars may contain especially high amounts, which help trigger the mass loss.

The study also shows that the number of blue stars decreases with distance from the core, tracing the drop in the amount of heavy elements.

Another possible explanation is that the blue stars are in close binary systems and have lost mass to their partners. This mass loss would expose the stars' hot cores. The astronomers were surprised to find that the ultra-blue stars are distributed in the galaxy in the same way as a population of binary stars with similar masses that were found in X-ray observations by NASA's Chandra X-ray Observatory.

The astronomers' next step is to create simulations of these stars to try to determine which scenario is the one that leads them on a different evolutionary path.

The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA's Goddard Space Flight Center manages the telescope. The Space Telescope Science Institute (STScI) conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, Inc., in Washington, D.C.

For images and more information about this study, visit: http://hubblesite.org/news/2012/03

NASA Hubble website: http://hubblesite.org/

ESA Hubble website: http://www.spacetelescope.org/

Image (mentioned), Video, Text, Credits: NASA / ESA.

Cheers, Orbiter.ch

Herschel and Spitzer See Nearby Galaxies' Stardust

ESA - HERSCHEL Mission logo / NASA - Spitzer Space Telescope patch.

Jan. 11, 2012

This new image shows the Large Magellanic Cloud galaxy in infrared light as seen by the Herschel Space Observatory, a European Space Agency-led mission with important NASA contributions, and NASA's Spitzer Space Telescope. Image credit: ESA / NASA / JPL-Caltech / STScI.

The cold dust that builds blazing stars is revealed in new images that combine observations from the Herschel Space Observatory, a European Space Agency-led mission with important NASA contributions; and NASA's Spitzer Space Telescope. The new images map the dust in the galaxies known as the Large and Small Magellanic Clouds, two of the closest neighbors to our own Milky Way galaxy.

The new images are available at the following links:
http://www.nasa.gov/mission_pages/herschel/multimedia/pia15254.html
http://www.nasa.gov/mission_pages/herschel/multimedia/pia15255.html

The Large Magellanic Cloud looks like a fiery, circular explosion in the combined Herschel-Spitzer infrared data. Ribbons of dust ripple through the galaxy, with significant fields of star formation noticeable in the center, center-left and top right (the brightest center-left region is called 30 Doradus, or the Tarantula Nebula, for its appearance in visible light). The Small Magellanic Cloud has a much more irregular shape. A stream of dust extends to the left in this image, known as the galaxy's "wing," and a bar of star formation appears on the right.

The colors in these images indicate temperatures in the dust that permeate the Magellanic Clouds. Colder regions show where star formation is at its earliest stages or is shut off, while warm expanses point to new stars heating dust surrounding them. The coolest areas and objects appear in red, corresponding to infrared light taken up by Herschel's Spectral and Photometric Imaging Receiver at 250 microns, or millionths of a meter. Herschel's Photodetector Array Camera and Spectrometer fills out the mid-temperature bands, shown in green, at 100 and 160 microns. The warmest spots appear in blue, courtesy of 24- and 70-micron data from Spitzer.

"Studying these galaxies offers us the best opportunity to study star formation outside of the Milky Way," said Margaret Meixner, an astronomer at the Space Telescope Science Institute, Baltimore, Md., and principal investigator for the mapping project. "Star formation affects the evolution of galaxies, so we hope understanding the story of these stars will answer questions about galactic life cycles."

This new image shows the Small Magellanic Cloud galaxy in infrared light from the Herschel Space Observatory a European Space Agency-led mission with important NASA contributions, and NASA's Spitzer Space Telescope. Image credit: ESA / NASA / JPL-Caltech / STScI.

The Large and Small Magellanic Clouds are the two biggest satellite galaxies of our home galaxy, the Milky Way, though they are still considered dwarf galaxies compared to the big spiral of the Milky Way. Dwarf galaxies also contain fewer metals, or elements heavier than hydrogen and helium. Such an environment is thought to slow the growth of stars. Star formation in the universe peaked around 10 billion years ago, even though galaxies contained lesser abundances of metallic dust. Previously, astronomers only had a general sense of the rate of star formation in the Magellanic Clouds, but the new images enable them to study the process in more detail.

The results were presented today at the 219th meeting of the American Astronomical Society in Austin, Texas.

Herschel is a European Space Agency cornerstone mission, with science instruments provided by consortia of European institutes and with important participation by NASA. NASA's Herschel Project Office is based at NASA's Jet Propulsion Laboratory, Pasadena, Calif. JPL contributed mission-enabling technology for two of Herschel's three science instruments. The NASA Herschel Science Center, part of the Infrared Processing and Analysis Center at the California Institute of Technology in Pasadena, supports the United States' astronomical community.

JPL manages the Spitzer Space Telescope mission for NASA's Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at Caltech. Caltech manages JPL for NASA.

For more information about Herschel, visit http://www.herschel.caltech.edu, http://www.esa.int/SPECIALS/Herschel/index.html

For more information about Spitzer, visit http://spitzer.caltech.edu/ and http://www.nasa.gov/spitzer

Images (mentioned), Text, Credit: NASA / Trent Perrotto / ESA / JPL / Whitney Clavin.

Best regards, Orbiter.ch

Stars Pop Onto the Scene in New WISE Image

NASA - WISE logo.

Jan. 11, 2012

 (Click on the image for enlarge)

This enormous section of the Milky Way galaxy is a mosaic of images from NASA's Wide-field Infrared Survey Explorer, or WISE. Image credit: NASA / JPL-Caltech / UCLA.

A new, large mosaic from NASA's Wide-Field Infrared Survey Explorer (WISE) showcases a vast stretch of cosmic clouds bubbling with new star birth. The region -- a 1,000-square-degree chunk of our Milky Way galaxy -- is home to numerous star-forming clouds, where massive stars have blown out bubbles in the gas and dust.

"Massive stars sweep up and destroy their natal clouds, but they continuously spark new stars to form along the way," said WISE Mission Scientist Dave Leisawitz of NASA Goddard Space Flight Center, Greenbelt, Md. Leisawitz is co-author of a new paper reporting the results in the Astrophysical Journal. "Occasionally a new, massive star forms, perpetuating the sequence of events and giving rise to the dazzling fireworks display seen in this WISE mosaic."

The new image is online at: http://www.nasa.gov/mission_pages/WISE/multimedia/pia15256.html .

The WISE space telescope mapped the entire sky two times in infrared light, completing its survey in February of 2011. Astronomers studying how stars form took advantage of WISE's all-encompassing view by studying several star-forming clouds, or nebulae, including 10 pictured in this new view.

The observations provide new evidence for a process called triggered star formation, in which the winds and sizzling radiation from massive stars compress gas and dust, inducing a second generation of stars. The same winds and radiation carve out the cavities, or bubbles, seen throughout the image.

Finding evidence for triggered star formation has proved more difficult than some might think. Astronomers are not able to watch the stars grow and evolve like biologists watching zebras in the wild. Instead, they piece together a history of star formation by looking at distinct stages in the process. It's the equivalent of observing only baby, middle-aged and elderly zebras with crude indicators of their ages. WISE is helping to fill in these gaps by providing more and more "specimens" for study.

"Each region we looked at gave us a single snapshot of star formation in progress," said Xavier Koenig, lead author of the new study at Goddard, who presented the results today in Austin, Texas, at the 219th meeting of the American Astronomical Society. "But when we look at a whole collection of regions, we can piece together the chain of events."

After looking at several of the star-forming nebulae, Koenig and his colleagues noticed a pattern in the spatial arrangement of newborn stars. Some were found lining the blown-out cavities, a phenomenon that had been seen before, but other new stars were seen sprinkled throughout the cavity interiors. The results suggest that stars are born in a successive fashion, one after the other, starting from a core cluster of massive stars and moving steadily outward. This lends support to the triggered star formation theory, and offers new clues about the physics of the process.

The astronomers also found evidence that the bubbles seen in the star-forming clouds can spawn new bubbles. In this scenario, a massive star blasts away surrounding material, eventually triggering the birth of another star massive enough to carve out its own bubble. A few examples of what may be first- and second-generation bubbles can be seen in the new WISE image.

"I can almost hear the stars pop and crackle," said Leisawitz.

The complete WISE catalogue will be released to the public astronomy community in the spring of 2012.

NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages, and operated WISE for NASA's Science Mission Directorate. The spacecraft was put into hibernation mode after it scanned the entire sky twice, completing its main objectives. Edward Wright is the principal investigator and is at UCLA. The mission was selected competitively under NASA's Explorers Program managed by the agency's Goddard Space Flight Center in Greenbelt, Md. The science instrument was built by the Space Dynamics Laboratory in Logan, Utah. The spacecraft was built by Ball Aerospace & Technologies Corp. in Boulder, Colo. Science operations and data processing take place at the Infrared Processing and Analysis Center at the California Institute of Technology in Pasadena. Caltech manages JPL for NASA.

More information is online at http://www.nasa.gov/wise, http://wise.astro.ucla.edu and http://jpl.nasa.gov/wise

Image (mentioned), Text, Credit: NASA / Trent J. Perrotto / JPL / Whitney Clavin.

Greetings, Orbiter.ch

Hubble Breaks New Ground with Discovery of Distant Exploding Star

NASA - Hubble Space Telescope patch.

Jan. 11, 2012

NASA's Hubble Space Telescope has looked deep into the distant universe and detected the feeble glow of a star that exploded more than 9 billion years ago. The sighting is the first finding of an ambitious survey that will help astronomers place better constraints on the nature of dark energy, the mysterious repulsive force that is causing the universe to fly apart ever faster.

These three images taken by NASA's Hubble Space Telescope reveal the emergence of an exploding star, called a supernova. Nicknamed SN Primo, the exploding star belongs to a special class called Type Ia supernovae, which are distance markers used for studying dark energy and the expansion rate of the universe. The top image shows part of the Hubble Ultra Deep Field, the region where astronomers were looking for a supernova blast. The white box shows where the supernova is later seen. The bottom left image is a close-up of the field without the supernova. A new bright object, identified as the supernova, appears in the image at bottom right. Credit: NASA, ESA, A. Riess (Space Telescope Science Institute and The Johns Hopkins University), and S. Rodney (The Johns Hopkins University).

"For decades, astronomers have harnessed the power of Hubble to unravel the mysteries of the universe," said John Grunsfeld, associate administrator for NASA’s Science Mission Directorate in Washington. "This new observation builds upon the revolutionary research using Hubble that won astronomers the 2011 Nobel Prize in Physics, while bringing us a step closer to understanding the nature of dark energy which drives the cosmic acceleration." As an astronaut, Grunsfeld visited Hubble three times, performing a total of eight spacewalks to service and upgrade the observatory.

The stellar explosion, nicknamed SN Primo, belongs to a special class called Type Ia supernovae, which are bright beacons used as distance markers for studying the expansion rate of the universe. Type Ia supernovae likely arise when white dwarf stars, the burned-out cores of normal stars, siphon too much material from their companion stars and explode.

SN Primo is the farthest Type Ia supernova with its distance confirmed through spectroscopic observations. In these types of observations, a spectrum splits the light from a supernova into its constituent colors. By analyzing those colors, astronomers can confirm its distance by measuring how much the supernova's light has been stretched, or red-shifted, into near-infrared wavelengths because of the expansion of the universe.

The supernova was discovered as part of a three-year Hubble program to survey faraway Type Ia supernovae, opening a new distance realm for searching for this special class of stellar explosion. The remote supernovae will help astronomers determine whether the exploding stars remain dependable cosmic yardsticks across vast distances of space in an epoch when the cosmos was only one-third its current age of 13.7 billion years.

Called the CANDELS+CLASH Supernova Project, the census uses the sharpness and versatility of Hubble's Wide Field Camera 3 (WFC3) to assist astronomers in the search for supernovae in near-infrared light and verify their distance with spectroscopy. CANDELS is the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey and CLASH is the Cluster Lensing and Supernova Survey.

"In our search for supernovae, we had gone as far as we could go in optical light," said Adam Riess, the project's lead investigator, at the Space Telescope Science Institute and The Johns Hopkins University in Baltimore, Md. "But it's only the beginning of what we can do in infrared light. This discovery demonstrates that we can use the Wide Field Camera 3 to search for supernovae in the distant universe."

The new results were presented on Jan. 11 at the American Astronomical Society meeting in Austin, Texas.

The supernova team's search technique involved taking multiple near-infrared images over several months, looking for a supernova's faint glow. After the team spotted the stellar blast in October 2010, they used WFC3's spectrometer to verify SN Primo's distance and to decode its light, finding the unique signature of a Type Ia supernova. The team then re-imaged SN Primo periodically for eight months, measuring the slow dimming of its light.

By taking the census, the astronomers hope to determine the frequency of Type Ia supernovae during the early universe and glean insights into the mechanisms that detonated them.

"If we look into the early universe and measure a drop in the number of supernovae, then it could be that it takes a long time to make a Type Ia supernova," said team member Steve Rodney of The Johns Hopkins University. "Like corn kernels in a pan waiting for the oil to heat up, the stars haven't had enough time at that epoch to evolve to the point of explosion. However, if supernovae form very quickly, like microwave popcorn, then they will be immediately visible, and we'll find many of them, even when the universe was very young. Each supernova is unique, so it's possible that there are multiple ways to make a supernova."

If astronomers discover that Type Ia supernovae begin to depart from how they expect them to look, they might be able to gauge those changes and make the measurements of dark energy more precise. Riess and two other astronomers shared the 2011 Nobel Prize in Physics for discovering dark energy 13 years ago, using Type Ia supernova to plot the universe's expansion rate.

The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA's Goddard Space Flight Center manages the telescope. The Space Telescope Science Institute (STScI) conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, Inc., in Washington, D.C.

For images and more information about Hubble, visit: http://www.nasa.gov/hubble"

NASA Hubble website: http://hubblesite.org/

ESA Hubble website: http://www.spacetelescope.org/

Images (mentioned), Text, Credit: NASA / Space Telescope Science Institute / Donna Weaver / Ray Villard.

Greetings, Orbiter.ch