Posted on by Fraser Cain

Valentine’s Day Greeting from Envisat

Image credit: ESA
Especially for Valentine’s Day, Envisat picks out a heart from the arid landscape of Africa’s Sahara.

This is a multi-temporal Advanced Synthetic Aperture Radar (ASAR) image of the central coast of Mauritania in West Africa, perched on the edge of the Sahara Desert.

The heart-shaped image seen at the centre of the picture is actually a land feature called the Sebkha Te-n-Dghamcha ? a large depression covering an area about 70 by 50 km across. ‘Sebkha’ is the Arabic for dry lake, and it was indeed once covered by water ? the area’s lowest point is more than three metres below sea level.

Most of the water evaporated, leaving behind layers of salt and other minerals including gypsum ? today supporting a thriving mining industry. What remains are shallow ponds of salty water, visible in the image.

While optical images are based on reflected light, radar images like this one show surface roughness, recording how radar pulses were scattered back from the ground towards a space-based detector.

Radar images are ordinarily in black and white. The colours come from combining three different image acquisitions into a single multi-temporal image, useful for highlighting changes occurring over time.

The first acquisition was on 23 November 2002, matching to red; the second on 23 March 2003, corresponding to green; and the last on 24 April 2003, shown as blue. The areas of whiteness in the final image represent areas of high surface reflectivity unchanged between acquisitions.

The saltpan surface of Sebkha Te-n-Dghamcha returns more radar backscatter than surrounding rock and desert sand. In the same way, the roofs and walls of Mauritania’s capital city Nouakchott reflect radar well, and so show up as the white area on the coast at the base of the image.

The different amounts of colours from each acquisition combine in the final image to form other hues that can be interpreted by experienced image processors ? for example, the magenta tint of the Atlantic Ocean shows it was at its calmest during the March acquisition.

Original Source: ESA News Release

Posted on by Fraser Cain

Oldest Quasars Give Clues About Cosmic Dark Age

Image credit: SDSS
The most distant known quasars show that some supermassive black holes formed when the universe was merely 6 percent of its current age, or about 700 million years after the big bang.

How black holes of several billion solar masses formed so rapidly in the very early universe is one mystery raised by astronomers with the Sloan Digital Sky Survey (SDSS). They have discovered 13 of the oldest, most distant quasars yet found.

“We hope to at least double that number in the next three years,” said Xiaohui Fan of the University of Arizona?s Steward Observatory in Tucson.

Fan led the SDSS team that discovered the distant quasars, which are compact but luminous objects thought to be powered by supermassive black holes. The most distant quasar, in the constellation Ursa Major, is roughly 13 billion light years away.

The most ancient quasars raise other tantalizing questions about the early universe. Fan talked about it today (Feb. 13) at the American Association for the Advancement of Science annual meeting in Seattle.

The infant universe was hydrogen and helium.

“But we see a lot of other elements around those early quasars,” Fan said. “We see evidence of carbon, nitrogen, iron and other elements, and it?s not clear how these elements got there. There is as much iron, proportionate to the population of those early systems, as there is in mature galaxies nearby.”

Astronomers estimate the current age of the universe at 13.7 billion years. Quasars in the early universe looked as mature as nearby galaxies that, like the Milky Way, formed a couple of billion years after the big bang.

Also, radio astronomers collaborating with SDSS researchers detected carbon monoxide, a key component of molecular clouds, near the ancient quasars.

All this evidence suggests that the first mature galaxies formed right along with the ancient supermassive black holes in the very early universe.

Although cosmologists aren?t panicked, they need to refine theory to clarify what?s going on.

Fan and his colleagues believe the oldest quasars can be used to probe the end of the Cosmic Dark Ages and the beginning of the Cosmic Renaissance.

In so-called Cosmic Dark Ages, the universe was a cold, opaque place without stars. Then came a critical phase where the universe went through a rapid transition. The first galaxies and quasars formed in the Cosmic Renaissance, heating the universe so it became the place we see today.

Fan and his colleagues believe some of their oldest known quasars may span the critical transition.

“Our observations suggest that what we may be seeing during this transition is atomic hydrogen becoming completely ionized. This ionization process was one of the important processes going on during the first one billion years.”

Current observations have just begun to reveal when and how this ionization process occurred. Data from distant quasars combined with other evidence, such as from the cosmic microwave background, which is relict radiation from the big bang, will begin to test theory of how the first galaxies appeared in the universe, Fan said.

It may take the large-aperture space telescope, NASA’s 6.5-meter James Webb Space Telescope, to really explore what happened between the Cosmic Dark Ages and the Cosmic Renaissance, Fan said.

Optical/infrared ground-based telescopes cannot detect objects red-shifted much beyond 6.5, Fan noted. Water vapor in Earth?s atmosphere absorbs longer infrared wavelengths, so it will take a space-based telescope, probably with an aperture larger than that of the NASA Spitzer Telescope now orbiting Earth, to study objects at redshift 7, 8, or 10 in detail, Fan said.

(So-called redshift is a phenomenon proportional to the velocity of a a celestial object speeding away from Earth. The lines in its spectrum shift toward longer, red wavelengths. Astronomers now believe that the most distant objects recede from Earth at the highest velocities, so the farther away an object is, the greater its redishift.)

Original Source: UA News Release

Posted on by Fraser Cain

Interplanetary Network Connects Rovers, Orbiters, Agencies and Earth

Image credit: ESA
A pioneering demonstration of communications between the European Space Agency’s Mars Express orbiter and NASA’s Mars exploration rover, Spirit, has succeeded.

On 6 February, while Mars Express was flying over the area that Spirit is examining, the orbiter transferred commands from Earth to the rover and relayed data from the rover back to Earth.

“This was the first in-orbit communication between ESA and NASA spacecraft, and we have also created the first working international communications network around another planet,” said Rudolf Schmidt, ESA’s Project Manager for Mars Express. “Both are significant achievements, two more ‘firsts’ for Mars Express and the Mars exploration rovers.”

Jennifer Trosper, Spirit Mission Manager at NASA’s Jet Propulsion Laboratory, California, USA, said, “We have an international interplanetary communications network established at Mars.”

ESA and NASA planned this demonstration as part of continuing efforts to cooperate in space.

The commands for the rover were first transferred from Spirit’s operations team at JPL to ESA’s European Space Operations Centre in Darmstadt, Germany, where they were translated into commands for Mars Express. The translated commands were transmitted to Mars Express, which used them to command Spirit. Spirit used its ultra-high-frequency antenna to transmit telemetry information to Mars Express, and the orbiter then relayed the data back to JPL via the European Space Operations Centre.

“This is excellent news,” said JPL’s Richard Horttor, project manager for NASA’s roles in Mars Express. “The communication sessions between Mars Express and Spirit were pristine. Not a single bit of data was missing or added, and there were no duplications.”

This exercise demonstrates the increased flexibility and capabilities of inter-agency cooperation and highlights the close mutual support that is essential when undertaking international space exploration.

More information on the ESA Mars Express mission can be found at http://mars.esa.int

Original Source: ESA News Release

Posted on by Fraser Cain

Spirit Sees Rising Pockets of Warm Air

Image credit: Cornell
An instrument on the NASA rover Spirit in Gusev crater on the surface of Mars has detected billows of warm air — called thermals — which rise from the planet’s surface into the thin atmosphere. Thermal changes create wind, and this was the first time these pockets of warm air have been detected on the planet.

“We now can see them (thermals) on Mars and learn how quickly they rise, giving us a better understanding of the wind dynamics there,” said Donald Banfield, Cornell senior research associate in space sciences, at a press briefing today (Feb. 12) at the Jet Propulsion Laboratory in Pasadena, Calif.

Atmospheric science is critical to understanding the complete Martian environment, explained Banfield. Before this mission, planetary scientists had scarce information on the planet’s surface-temperature structure. Satellites orbiting Mars provided temperature information for the upper portions of the planet’s atmosphere. Until now, the temperatures on the surface could not be measured.

Banfield said that wind is sculpting the geological features on Mars. “Wind is the issue. It creates dunes, dust devils and dust storms, and understanding it is important,” he said.

Before the rover Spirit experienced memory malfunctions in January, its Mini-Thermal Emission Spectrometer device, or MiniTES, gathered one eight-minute block of spectral data by staring at the Martian sky. The data, examined by Michael Smith of NASA’s Goddard Space Flight Center and Banfield, showed pockets of warm air rising every few minutes. Both are members of the Mars Exploration Rover mission’s science team.

The MiniTES instrument can read the temperature by analyzing the infrared spectrum in the lower atmosphere. Banfield explained that since the Martian atmosphere is mostly carbon dioxide, the instrument perceives the infrared light wavelength and translates it into temperature.

“We saw warmer and cooler places in the Mars atmosphere,” Banfield told the media. “There were warm blobs and cold blobs passing over the rover.”

As the sun rises each day on Mars, the surface temperature climbs much like on Earth. “There is an upward trend of warm air, convection,” said Banfield. “This is exciting data?this is novel data.”

Meanwhile on the other side of Mars, the rover Opportunity, now at the rock outcrop Stone Mountain on the Meridiani plain, obtained an extreme close-up of round, blueberry-shaped formations in the soil. The spherically shaped formations are about the size of BB pellets and the mission scientists have begun to study them for clues about the soil’s development.

Original Source: Cornell News Release

Posted on by Fraser Cain

Astronomers Find a Huge Diamond in Space

Image credit: CfA
When choosing a Valentine’s Day gift for a wife or girlfriend, you can’t go wrong with diamonds. If you really want to impress your favorite lady this Valentine’s Day, get her the galaxy’s largest diamond. But you’d better carry a deep wallet, because this 10 billion trillion trillion carat monster has a cost that’s literally astronomical!

“You would need a jeweler’s loupe the size of the Sun to grade this diamond!” says astronomer Travis Metcalfe (Harvard-Smithsonian Center for Astrophysics), who leads a team of researchers that discovered the giant gem. “Bill Gates and Donald Trump together couldn’t begin to afford it.”

When asked to estimate the value of the cosmic jewel, Ronald Winston, CEO of Harry Winston Inc., indicated that such a large diamond probably would depress the value of the market, stating, “Who knows? It may be a self-deflating prophecy because there is so much of it.” He added, “It is definitely too big to wear!”

The newly discovered cosmic diamond is a chunk of crystallized carbon 50 light-years from the Earth in the constellation Centaurus. (A light-year is the distance light travels in a year, or about 6 trillion miles.) It is 2,500 miles across and weighs 5 million trillion trillion pounds, which translates to approximately 10 billion trillion trillion carats, or a one followed by 34 zeros.

“It’s the mother of all diamonds!” says Metcalfe. “Some people refer to it as ‘Lucy’ in a tribute to the Beatles song ‘Lucy In The Sky With Diamonds.'”

The diamond star completely outclasses the largest diamond on Earth, the 530-carat Star of Africa which resides in the Crown Jewels of England. The Star of Africa was cut from the largest diamond ever found on Earth, a 3,100-carat gem.

The huge cosmic gem (technically known as BPM 37093) is actually a crystallized white dwarf. A white dwarf is the hot core of a star, left over after the star uses up its nuclear fuel and dies. It is made mostly of carbon and is coated by a thin layer of hydrogen and helium gases.

For more than four decades, astronomers have thought that the interiors of white dwarfs crystallized, but obtaining direct evidence became possible only recently.

“The hunt for the crystal core of this white dwarf has been like the search for the Lost Dutchman’s Mine. It was thought to exist for decades, but only now has it been located,” says co-author Michael Montgomery (University of Cambridge).

The white dwarf studied by Metcalfe, Montgomery, and Antonio Kanaan (UFSC Brazil), is not only radiant but also harmonious. It rings like a gigantic gong, undergoing constant pulsations.

“By measuring those pulsations, we were able to study the hidden interior of the white dwarf, just like seismograph measurements of earthquakes allow geologists to study the interior of the Earth. We figured out that the carbon interior of this white dwarf has solidified to form the galaxy’s largest diamond,” says Metcalfe.

Our Sun will become a white dwarf when it dies 5 billion years from now. Some two billion years after that, the Sun’s ember core will crystallize as well, leaving a giant diamond in the center of our solar system.

“Our Sun will become a diamond that truly is forever,” says Metcalfe.

A paper announcing this discovery has been submitted to The Astrophysical Journal Letters for publication.

Original Source: CfA News Release

Posted on by Fraser Cain

Space Exploration Commission Holds First Hearing

The commission appointed to investigate the feasibility of US President’s Bush’s new space initiative held its first public hearing on Wednesday, and heard testimony from five aerospace experts. The testimony from Norman Augustine, retired chairman of Lockheed Martin Corp, said that a human mission to Mars would be very expensive, probably on the order of $150 billion over the next 10 years. He urged the commission to make sure this doesn’t get done “on the cheap”; and pointed to NASA’s history of underestimating the costs for major new projects. The commission is expected to deliver its report in approximately 120 days.

Posted on by Fraser Cain

Wallpaper: Spitzer’s Valentine Rose

Image credit: NASA/JPL
Out of the dark and dusty cosmos comes an unusual valentine ? a stellar nursery resembling a shimmering pink rosebud. This cluster of newborn stars, called a reflection nebula, was captured by state-of-the-art infrared detectors onboard NASA’s new Spitzer Space Telescope, formerly known as the Space Infrared Telescope Facility.

The Valentine’s Day image is available online at http://www.spitzer.caltech.edu and http://photojournal.jpl.nasa.gov/catalog/PIA05266.

“The picture is more than just pretty,” said Dr. Thomas Megeath, principal investigator for the latest observations and an astronomer at the Harvard Smithsonian Center for Astrophysics, Cambridge, Mass. “It helps us understand how stars form in the crowded environments of stellar nurseries.”

Located 3,330 light-years away in the constellation Cepheus and spanning 10 light-years across, the rosebud-shaped nebula, numbered NGC 7129, is home to some 130 young stars. Our own Sun is believed to have grown up in a similar family setting.

Previous images of NGC 7129 taken by visible telescopes show a smattering of hazy stars spotted against a luminescent cloud. Spitzer, by sensing the infrared radiation or heat of the cluster, produces a much more detailed snapshot. Highlighted in false colors are the hot dust particles and gases, respectively, which form a nest around the stars. The pink rosebud contains adolescent stars that blew away blankets of hot dust, while the green stem holds newborn stars whose jets torched surrounding gases.

Outside of the primary nebula, younger proto-stars can also be seen for the first time. “We can now see a few stars beyond the nebula that were previously hidden in the dark cloud,” said Megeath.

In addition, the findings go beyond what can be seen in the image. By analyzing the amount and type of infrared light emitted by nearly every star in the cluster, scientists were able to determine which ones support the swirling rings of debris, called circumstellar discs, which eventually coalesce to form planets. Roughly half of the stars observed were found to harbor discs.

These observations will ultimately help astronomers determine how stellar nurseries shape the development of planetary systems similar to our own.

Launched on August 25, 2003, from Cape Canaveral Air Force Station, Florida, the Spitzer Space Telescope is the fourth of NASA?s Great Observatories, a program that also includes the Compton Gamma Ray Observatory, Chandra X-ray Observatory and Hubble Space Telescope.

JPL manages the Spitzer Space Telescope mission for NASA’s Office of Space Science, Washington, D.C. Science operations are conducted at the Spitzer Science Center at the California Institute of Technology in Pasadena. JPL is a division of Caltech.

Additional information about the Spitzer Space Telescope is available at http://www.spitzer.caltech.edu.

Original Source: NASA/JPL News Release

Posted on by Fraser Cain

Search Ends for Beagle 2

Image credit: ESA
Beagle 2, the British-built element of ESA’s Mars Express mission, has failed to communicate since its first radio contact was missed shortly after it was due to land on Mars on Christmas Day. The Beagle 2 Management Board met in London on Friday 6 February and, following an assessment of the situation, declared Beagle 2 lost.

Today, the UK Science Minister Lord Sainsbury and the European Space Agency (ESA) announced that an ESA/UK inquiry would be held into the failure the Beagle 2 lander.

Lord Sainsbury, of the Department of Trade and Industry, said: “I believe such an inquiry will be very useful. The reasons identified by the Inquiry Board will allow the experience gained from Beagle 2 to be used for the benefit of future European planetary exploration missions.”

The ESA Director General, Jean-Jacques Dordain, said : “ESA is a partnership of its Member States and sharing the lessons learnt from good and bad experiences is fundamental in cooperation.”

The Inquiry Board is to be chaired by the ESA Inspector General, Ren? Bonnefoy. The UK deputy chairman will be David Link MBE.

The inquiry will investigate whether it can be established why Beagle 2 may have failed and set out any lessons which can be learnt for future missions. Such inquiries are routine in the event of unsuccessful space missions and this one will help inform future ESA robotic missions, to Mars and other bodies in the solar system.

The Inquiry Board will be set up under normal ESA procedures by the Inspector General. Because the inquiry is into a British-built lander, it will report to Lord Sainsbury as well as to the Director General of ESA.

Its terms of reference are as follows:

1. Technical Issues

* Assess the available data/documentation pertaining to the in-orbit operations, environment and performance characterisation, and to the on-ground tests and analyses during development;
* Identify possible issues and shortcomings in the above and in the approach adopted, which might have contributed to the loss of the mission.

2. Programmatics

* Analyse the programmatic environment (i.e. decision-making processes, level of funding and resources, management and responsibilities, interactions between the various entities) throughout the development phase;
* Identify possible issues and shortcomings which might have contributed to the loss of the mission.

The Board, made up of people with no direct involvement in the Beagle 2 mission, is expected to begin work shortly and report by the end of March 2004.

The key players in the Beagle 2 mission, including Colin Pillinger, the Open University, the University of Leicester, the National Space Science Centre, EADS-Astrium, and BNSC partners have all welcomed the setting up of the Inquiry Board.

Original Source: ESA News Release

Posted on by Fraser Cain

New Discoveries About Gravitational Lenses

Image credit: Hubble
Many examples are known where a galaxy acts as a gravitational lens, producing multiple images on the sky of a more distant object like a bright quasar hidden behind it. But there has been a persistent mystery for over 20 years: Einstein’s general theory of relativity predicts there should be an odd number of images, yet almost all observed lenses have only 2 or 4 known images. Now, astronomer Joshua Winn of the Harvard-Smithsonian Center for Astrophysics (CfA) and two former CfA colleagues, David Rusin (now at the University of Pennsylvania) and Christopher Kochanek (The Ohio State University), have identified a third, central image of a lensed quasar. Radio observations of the system known as PMN J1632-0033 in the constellation Ophiuchus uncovered a faint central image, which can be used to investigate the properties of the lensing galaxy and the supermassive black hole expected to lie at its center.

“Finding this central image is interesting in its own right, but is even more important for what it can tell us about the lensing galaxy. This offers us a new tool for studying galaxies so far away that, even to the Hubble Space Telescope, they’re just faint smudges,” said Winn.

Quasars are extremely distant and bright objects believed to be powered by supermassive black holes. They shine brightly by converting the gravitational energy of matter falling into the black hole into light and other types of radiation, such as radio waves.

In gravitational lensing, light rays from a quasar which pass close to a galaxy are bent by the galaxy’s gravitational field, much as they would be bent when passing through a glass lens. The denser the center of a galaxy, and the stronger its gravity, the fainter the central image will be. Yet this central image, whose light has passed closest to the middle of the lensing galaxy, can tell us much about that galaxy’s core. That opportunity makes finding such central images particularly desirable.

In the system PMN J1632-0033, a radio-loud quasar at redshift z=3.42 (a distance of about 11.5 billion light-years) is being lensed by an elliptical galaxy at redshift z~1 (about 8 billion light-years away). Two images of the quasar were known to exist, and a third, very faint radio source was suspected to be the central image. However, that third source was right on top of the lensing galaxy, and so might have been intrinsic to the lensing galaxy itself.

By observing the radio “color,” or spectrum, of all three images using the National Science Foundation’s Very Large Array and Very Long Baseline Array, Winn and his colleagues provided compelling evidence that the third source is indeed the quasar’s central image. Its spectrum is essentially identical to the other two images, except at low frequencies where some of the radio energy was absorbed by the lensing galaxy.

The geometry and properties of the quasar’s three images already are telling us about the core of the lensing galaxy. For example, its central black hole weighs less than 200 million solar masses. Also, its surface density (amount of matter as projected against the plane of the sky) at the location of the central image is more than 20,000 solar masses per square parsec. (For comparison, the surface density of the Milky Way near our sun is about 50 solar masses per square parsec.) Both figures for the lensing galaxy agree with expectations based on detailed observations of galaxies hundreds of times closer to the Earth.

“Almost all of our knowledge about galaxy centers comes from studying very nearby galaxies. The remarkable thing about central images is that you can get similar information about the cores of galaxies hundreds of times farther away, and billions of years younger than our neighboring galaxies,” said Winn.

This research is available online at http://arxiv.org/abs/astro-ph/0312136 and will be published in the February 12, 2004 issue of the journal Nature.

Headquartered in Cambridge, Mass., the Harvard-Smithsonian Center for Astrophysics is a joint collaboration between the Smithsonian Astrophysical Observatory and the Harvard College Observatory. CfA scientists, organized into six research divisions, study the origin, evolution and ultimate fate of the universe.

Original Source: Harvard CfA News Release

Posted on by Fraser Cain

Rosetta Attached to Its Launch Hardware

Image credit: Arianespace
Preparations for Flight 158 entered a new phase this week as the mission’s Rosetta payload made its initial contact with hardware from the Ariane 5 launcher.

This activity occurred in the Spaceport’s S3B clean room, where Rosetta was positioned on a cone-shaped adapter that serves as the interface structure between the deep-space probe and Ariane 5.

Rosetta is now ready for its transfer to the Ariane 5 Final Assembly building, where the probe will be encapsulated in its protective payload fairing and then installed atop the launch vehicle.

Liftoff of Flight 158 is set for the early morning hours of February 26 from the Spaceport’s ELA-3 launch complex. Instead of a typical launch window used for missions geostationary satellite payloads, Flight 158 has two specific launch slots: one at 49 seconds past 4:16 a.m., and the other at 49 seconds past 4:36 a.m.

Duration of Flight 158 also is unusual for an Ariane 5 mission. After a standard separation of the two solid booster stages and burnout of the central core stage, the Ariane 5’s EPS upper stage will enter a prolonged ballistic phase, followed by its ignition at almost 2 hours after liftoff. Rosetta will be separated from the stage approximately 14 minutes later, embarking on an Earth escape trajectory that will lead to its encounter with comet Churyumov-Gerasimenko in 2014.

Rosetta uses a cubic-shaped spacecraft bus built by Astrium in Germany, and has a liftoff mass of about 3,000 kg. The comet-intercept was under responsibility of the European Space Agency and will include the deployment of a small lander to the surface of Churyumov-Gerasimenko.

Original Source: Arianespace News Release