Posted on by Fraser Cain

Glitch Delays X-43 Test

Image credit: NASA
The flight of NASA’s X-43A has been postponed, due to an incident with the rudder actuator on the booster. On Feb 11, during setup at Orbital Sciences Corporation for testing of the rudder and its actuator, an anomaly caused the actuator to go hard over and hit its mechanical stop, exceeding the torque to which the units were qualified.

Although the actuator may still function normally, it will have to be replaced. A joint government/contractor incident investigation is under way to determine the cause and corrective actions.

Before this incident, the program was considering a delay of the flight to late March to retune the booster autopilot, to optimize its performance based on the latest test data. With the requirement for a replacement actuator, the two activities will now be done in parallel. Planning is now focused on a late-March to early-April flight.

The X-43A is a high-risk, high-payoff flight research program. Designed to fly at seven and 10 times the speed of sound, and use scramjet engines instead of traditional rocket power, the small, 12-foot-long X-43A could represent a major leap forward toward the goal of providing faster, more reliable and less expensive access to space.

The stack, consisting of the X-43A and its modified Pegasus booster, will be air-launched by NASA’s B-52 carrier aircraft at 40,000 feet altitude. The booster will accelerate the experimental vehicle to Mach 7 at approximately 95,000 feet altitude. At booster burnout, the X-43 will separate and fly under its own power on a preprogrammed path. The flight will take place over a restricted Navy Pacific Ocean test range off the coast of Southern California.

Original Source: NASA News Release

Posted on by Fraser Cain

Venus Blazes Beside the Moon

Image credit: Sky and Telescope
Treat yourself to an eye-catching celestial treat on Monday evening, February 23, 2004. At dusk, just look to the west. There you’ll find Venus, the magnificently brilliant “Evening Star,” blazing to the right of the crescent Moon. Provided it’s clear, you can’t miss this celestial splendor. Venus will outshine every star in the sky and may even appear about as bright as the 3?-day-old Moon itself.

The Moon will have only about 15 percent of its disk illuminated by the Sun. But look closer and you will likely make out the rest of the lunar disk glowing faintly ? you may even see the Man in the Moon. This effect is known as earthshine. What you are seeing is reflected sunlight from Earth shining onto the Moon’s night landscape, providing a dull illumination.

Venus is so brilliant for two reasons: it’s closer to the Sun than Earth so it gets lit more brightly, and its white clouds reflect sunlight very well. Although the Moon and Venus look close together, they’re actually at very different distances. On the night of the 23rd, the Moon is 244,000 miles (392,000 kilometers) from Earth, but Venus is 370 times farther: 90 million miles (145 million km) away. Venus is sometimes called our sister planet because it is similar in size to Earth.

For members of the broadcast media, the timing of this celestial pairing will make for a perfect opportunity to take your cameras outside for a live shot during the evening news. Be sure to take advantage.

Original Source: Sky and Telescope News Release

Posted on by Fraser Cain

Opportunity Digs Out a Trench

Image credit: NASA/JPL
If you’re a geologist, you always keep a shovel handy. One of the best ways to understand the geologic history of an area is to dig down and examine the layers of material. NASA’s rovers couldn’t bring a shovel to Mars, but they still have a way to get a look down under the surface – they can dig a trench with their wheels.

Engineers perfected a technique here on Earth where the twin Mars Exploration Rovers lock up five of their six wheels and turn the sixth to excavate a trench down into the Martian soil. Depending on the kind of dirt, this “shovel” can get down more than 10 cm, and reveal the deeper layers.

And today, NASA’s Opportunity rover did just that.

The rover used its right front wheel to dig a trench into the soil at an area called Hematite ridge. After the rover completed the operation, engineers were able to confirm that it had scooped out dirt approximately 8 to 10 cm deep and 20 cm wide. The rover’s hazard cameras confirmed that the subsurface soil is much brighter than the dark-red topsoil.

The area was selected because it’s rich in hematite; a mineral on Earth which usually forms in the presence of liquid water (although, it can be created through volcanic processes as well).

With the deeper soil on the surface, the rover can now use its suite of scientific instruments to measure the soil, to help scientists get a better idea of what could have deposited the hematite.

Once Opportunity completes its analysis of the trenched soil, it will make its way to a site called El Capitan, which is part of a rock outcrop on the side of the crater that the rover landed inside.

Posted on by Fraser Cain

Titan Could Help the Study of Oceanography

Image credit: Mark Robertson-Tessi
After a 7-year interplanetary voyage, NASA?s Cassini spacecraft will reach Saturn this July and begin what promises to be one of the most exciting missions in planetary exploration history.

After years of work, scientists have just completed plans for Cassini?s observations of Saturn?s largest moon, Titan.

“Of course, no battle plan survives contact with the enemy,” said Ralph Lorenz, an assistant research scientist at the University of Arizona?s Lunar and Planetary Laboratory in Tucson.

The spacecraft will deploy the European Space Agency?s Huygens probe to Titan for a January 2005 landing. Nearly half the size of Earth, frigid Titan is the only moon in the solar system with a thick atmosphere. Smog has prevented scientists from getting more than a tantalizing hint of what may be on the moon?s amazing surface.

“Titan is a completely new world to us, and what we learn early on will likely make us want to adjust our plans. But we have 44 flybys of Titan in only four years, so we have to have a basic plan to work to.”

Scientists have long thought that, given the abundant methane in Titan’s atmosphere, there might be liquid hydrocarbons on Titan. Infrared maps taken by the Hubble Space Telescope and ground-based telescopes show bright and dark regions on Titan’s surface. The maps indicate the dark regions are literally pitch-black, suggesting liquid ethane and methane.

Last year, data from the Arecibo telescope showed there are many regions on Titan that are both fairly radar-dark and very smooth. One explanation is that these areas are seas of methane and ethane. These two compounds, present in natural gas on Earth, are liquid at Titan’s frigid surface temperature, 94 degrees Kelvin (minus 179 degrees Celsius).

Titan will be an outstanding laboratory for oceanography and meteorology, Lorenz predicts.

“Many important oceanographical processes, like the transport of heat from low to high latitudes by ocean currents, or the generation of waves by wind, are known only empirically on Earth,” Lorenz said. “If you want to know how big waves get for a given windspeed, you just go out and measure both of them, get a lot of datapoints, and fit a line through them.

“But that’s not the same as understanding the underlying physics and being able to predict how things will be different if circumstances change. By giving us a whole new set of parameters, Titan will really open our understanding of how oceans and climates work.”

Cassini/Huygens will answer many questions, among them:

Are the winds strong enough to whip up waves that will cut cliffs in the lakesides? Will they form steep beaches, or will the strong tides caused by Saturn’s gravity be a bigger effect, forming wide, shallow tidal flats?

How deep are Titan’s seas? This question bears on the history of Titan’s atmosphere, which is the only other significant nitrogen atmosphere in the solar system, apart from the one you’re breathing now.

And do the oceans have the same composition everywhere? Just as there are salty seas and freshwater lakes on Earth, some seas on Titan may be more ethane-rich than others.

Lorenz began working on the Huygens project as an engineer for the European Space Agency in 1990, then earned his doctorate from the University of Kent at Canterbury, England, while building one of the probe’s experiments. He joined the University of Arizona in 1994 where he started work on Cassini’s Radar investigation. He is a co-author of the book, “Lifting Titan’s Veil” published in 2002 by Cambridge University Press.

Original Source: UA News Release

Posted on by Fraser Cain

Why is Mars So Dry?

Image credit: NASA/JPL
The MER rovers Spirit and Opportunity, now traveling on the surface of Mars, are exploring a geography drier than the driest desert on Earth. Despite the polar ice caps and suspected pockets of liquid water beneath the martian surface, the amount of water on Mars is but a teaspoon compared to the vast watery reserves of Earth. Why is Mars so dry?

The inner planets of our solar system – Mars, Earth, Venus and Mercury – formed by the accumulation of small rocks and dust that swirled around the sun in its earliest years. If the Earth and Mars are made of the same stardust, they should have been born with about the same ratio of water.

Many scientists think Mars once was very watery, but lost its oceans due to the low mass of the planet. This, combined with a thin atmosphere, allowed most of the water on Mars to evaporate out into space.

But according to a study by Jonathan Lunine of the Lunar and Planetary Laboratory at the University of Arizona, the Red Planet was dry from the very beginning.

Lunine, writing in the journal Icarus in 2003 with colleagues John Chambers, Alessandro Morbidelli, and Laurie Leshin, says that Mars was originally a planetary embryo. In essence, a planetary embryo is a very large asteroid that can be as massive as Mercury or Mars. This pre-Mars embryo existed in the asteroid belt, which at the time was more widely dispersed in the solar system, spread out between 0.5 to 4 AU from the sun. Today the main asteroid belt is roughly at 2 to 4 AU, located between Mars (1.5 AU) and Jupiter (5.2 AU).

Lunine says that Mars grew to its present size from accumulations of smaller asteroids and comets. He says that the more massive Earth, in comparison, mostly formed from large planetary embryos colliding into each other.

“By chance Mars was not struck by giant asteroids while Earth was – the lucky versus unlucky pedestrian,” says Lunine. “But Mars was struck by much smaller bodies because these are so numerous.”

The Earth currently orbits the sun at 1 AU. Lunine says that planetary embryos in this orbit would not have had much water. Early in the sun’s evolution, during planetary formation, the dusty disk that surrounded the young star was very hot. Water-bearing compounds would not have been able to form in this disk at 1 AU.

Since Mars is further away from the sun than Earth, and closer to the cooler, “moist” regions of the asteroid belt, it would seem logical that Mars would have been born with more water. Yet Lunine says that Mars probably acquired only 6 to 27 percent of an Earth’s ocean (1 Earth ocean =1.5 ?1021 kg).

That’s because some of the planetary embryos that eventually constituted the Earth were saturated with water. While 90 percent of the embryos that formed the Earth were from the 1 AU region, and therefore dry, 10 percent were from 2.5 AU and beyond. Embryos coming from this distance would’ve had large supplies of water. Smaller asteroids coming from this distance would’ve contributed to the Earth’s water supply as well. At most, Lunine says that only 15 percent of Earth’s water came from comets.

Mars, meanwhile, had the bad luck to be born as a single dry rock. Mars eventually received some water late in the formation game, after its core had already formed and it had nearly reached its present mass. According to Lunine’s scenario, Jupiter also gained its present day mass around this time. Jupiter’s gravity then either sucked in nearby asteroids or caused them to scatter outwards. The proto-Mars somehow escaped being shifted by Jupiter’s gravity, but was bombarded by the outward-bound asteroids.

“The impacts of small asteroids and comets constituted a “late veneer” which added water to Mars, in contrast to the picture for Earth where water was added through collisions with Mercury-sized embryos throughout a growth period of some tens of millions of years,” the scientists write.

Although Mars doesn’t form in their computer model, the scientists think that may reflect the chaotic nature of planetary formation, where the directions of planetary embryos and asteroids are unpredictable and many outcomes are possible.

“There is a fair amount of randomness involved in building the terrestrial planets, so ending up with a Mars that did not happen to accrete many water-rich planetesimals is a possible occurrence,” says Alan Boss of the Carnegie Institution of Washington. “This may well help explain the paucity of water on modern-day Mars.”

Such differences in planetary formation also could occur among the inner planets of other solar systems. So far, astronomers know of 104 stars that have planets orbiting them. All of the extrasolar planets found so far are gas giants, but it seems likely that terrestrial planets like Mars and the Earth also could orbit distant stars, even though we do not yet have the technology to detect them.

If some inner terrestrial planets are formed by collisions of several planetary embryos, while others are embryos that only gather up moist comets and asteroids, then planets around these other stars could have very different amounts of water. Lunine suggests that the timing and formation of the gas giant planets in each solar system will play an important role in this process, just as Jupiter has influenced the character of our own solar system.

Lunine currently has a paper in Icarus, with Tom Quinn and Sean Raymond of the University of Washington, on the possible variation in water abundance for terrestrial planets around other stars. In addition, he is carefully watching the data collected by the MER rovers Spirit and Opportunity, as well as the satellites currently orbiting Mars.

“Odyssey, MER, and Mars Express will determine how much water exists at present, hopefully, and provide better constraints on past water abundance,” says Lunine. “I am particularly interested in the MARSIS radar results, and those of its successor – SHARAD.”

MARSIS is a radar device on the Mars Express satellite that can look through the top five kilometers of martian crust to search for layers of water and ice. The Italian space agency is planning to fly a shallow subsurface radar, called SHARAD, on NASA’s Mars Reconnaissance Orbiter to see if water ice is present at depths greater than one meter. While MARSIS has a higher penetration capability, it has much lower resolution than SHARAD will have.

Original Source: Astrobiology Magazine

Posted on by Fraser Cain

Titan Launches Defense Satellite

Image credit: Boeing
On the final mission for the program, a Boeing [NYSE:BA] Inertial Upper Stage (IUS) payload booster vehicle successfully deployed a U.S. Air Force Defense Support Program (DSP) satellite today.

The IUS-10 and its integrated payload, DSP-22, were launched aboard a Titan IV B rocket, which also flew with a Boeing-made fairing. Liftoff occurred at 1:50 p.m. EST from Space Launch Complex 40 at Cape Canaveral Air Force Station, Fla.

Upon separation from the rocket, IUS-10 fired its two stages to propel the spacecraft toward its geosynchronous orbit. Following roll maneuvers, the IUS successfully deployed the spacecraft.

?This last IUS mission added a critical asset to our nation?s military space program with the successful launch of DSP-22,? said Bill Benshoof, Boeing IUS program manager. ?The flight of IUS-10 concludes a 22-year journey for one of the most successful upper stages ever built and flown.?

The Boeing IUS program has supported national security, telecommunications and science missions with successful spacecraft deployments for the U.S. Department of Defense, the original Tracking and Data Relay Satellite constellation, and the Magellan, Galileo, Ulysses and Chandra missions for NASA.

Adding to the celebration of today?s successful last flight of the IUS, the Boeing IUS team received honors this week by the Air Force Association at the AFA?s Air Warfare Symposium in Orlando, Fla., for its significant contributions to the advancement of Air Force space activities in the last 50 years.

The Boeing IUS has been launched from the space shuttle and Titan IV rockets. There have been 24 IUS missions flown to date ? 15 launched from the shuttle and nine launched from the Titan IV.

A typical IUS mission launched from a Titan IV involves IUS separation from the rocket?s second stage booster approximately nine minutes into flight. The IUS takes over responsibility for the remainder of the powered portion of the flight.

For the next six hours and 45 minutes, the IUS autonomously performs all functions to place the spacecraft into its proper orbit.

The first IUS engine burn occurs a little over one hour into the IUS booster?s flight. The second solid rocket motor ignites about six-and-a-half hours into flight followed by a coast phase, and then, separation of the spacecraft.

IUS vehicle production was completed at Boeing in Kent, Wash. Spacecraft integration, checkout, ground operations and launch preparation activities were conducted at Cape Canaveral.

Boeing also produces the payload fairing for the Titan IV program. A 56-foot long fairing was used for the DSP-22 mission. Boeing-built fairings have flown on all 37 Titan IV launches to date and will fly aboard the remaining two Titan IV launches.

?This successful launch continues the 100 percent mission success record for the Titan IV payload fairing,? said Richard Peters, program manager and chief engineer, Boeing Titan fairing program.

The fairing for the DSP-22 mission was produced at Boeing in Huntington Beach, Calif., with the fairing?s thermal protection system applied at Boeing in Pueblo, Colo.

The Boeing IUS and Titan fairing programs are managed by Boeing Expendable Launch Systems in Huntington Beach.

The Defense Support Program is a satellite surveillance system providing the United States and its allies with ballistic missile early warning and other information related to missile launches, surveillance and the detonation of nuclear weapons.

A unit of The Boeing Company, Integrated Defense Systems is one of the world?s largest space and defense businesses. Headquartered in St. Louis, Boeing Integrated Defense Systems is a $27 billion business. It provides systems solutions to its global military, government and commercial customers. It is a leading provider of intelligence, surveillance and reconnaissance; the world?s largest military aircraft manufacturer; the world?s largest satellite manufacturer and a leading provider of space-based communications; the primary systems integrator for U.S. missile defense; NASA?s largest contractor; and a global leader in launch services.

Original Source: Boeing News Release

Posted on by Fraser Cain

New Galaxy Beats Distance Record

Image credit: Hubble
An international team of astronomers may have set a new record in discovering what is the most distant known galaxy in the universe. Located an estimated 13 billion light-years away, the object is being viewed at a time only 750 million years after the big bang, when the universe was barely 5 percent of its current age.

The primeval galaxy was identified by combining the power of NASA’s Hubble Space Telescope and CARA’s W. M. Keck Telescopes on Mauna Kea in Hawaii. These great observatories got a boost from the added magnification of a natural “cosmic gravitational lens” in space that further amplifies the brightness of the distant object.

The newly discovered galaxy is likely to be a young galaxy shining during the end of the so-called “Dark Ages” ? the period in cosmic history which ended with the first galaxies and quasars transforming opaque, molecular hydrogen into the transparent, ionized universe we see today.

The new galaxy was detected in a long exposure of the nearby cluster of galaxies Abell 2218, taken with the Advanced Camera for Surveys on board the Hubble Space Telescope. This cluster is so massive that the light of distant objects passing through the cluster actually bends and is amplified, much as a magnifying glass bends and magnifies objects seen through it. Such natural gravitational “telescopes” allow astronomers to see extremely distant and faint objects that could otherwise not be seen. The extremely faint galaxy is so far away its visible light has been stretched into infrared wavelengths, making the observations particularly difficult.

“As we were searching for distant galaxies magnified by Abell 2218, we detected a pair of strikingly similar images whose arrangement and color indicate a very distant object,” said astronomer Jean-Paul Kneib (Observatoire Midi-Pyrenees and Caltech), who is lead author reporting the discovery in a forthcoming article in the Astrophysical Journal.

Analysis of a sequence of Hubble images indicate the object lies in between a redshift of 6.6 and 7.1, making it the most distant source currently known. However, long exposures in the optical and infrared taken with spectrographs on the 10-meter Keck telescopes suggest that the object has a redshift towards the upper end of this range, around redshift 7.

Redshift is a measure of how much the wavelengths of light are shifted to longer wavelengths. The greater the shift in wavelength toward the redder regions of the spectrum, the more distant the object is.

“The galaxy we have discovered is extremely faint, and verifying its distance has been an extraordinarily challenging adventure,” said Dr. Kneib. “Without the magnification of 25 afforded by the foreground cluster, this early object could simply not have been identified or studied in any detail at all with the present telescopes available. Even with aid of the cosmic lens, the discovery has only been possible by pushing our current observatories to the limits of their capabilities!”

Using the combination of the high resolution of Hubble and the large magnification of the cosmic lens, the astronomers estimate that this object, although very small ? only 2,000 light-years across ? is forming stars extremely actively. However, two intriguing properties of the new source are the apparent lack of the typically bright hydrogen emission line and its intense ultraviolet light which is much stronger than that seen in star-forming galaxies closer by.

“The properties of this distant source are very exciting because, if verified by further study, they could represent the hallmark of a truly young stellar system that ended the Dark Ages,” added Dr. Richard Ellis, Steele Professor of Astronomy at Caltech, and a co-author in the article.

The team is encouraged by the success of their technique and plans to continue the search for more examples by looking through other cosmic lenses in the sky. Hubble’s exceptional resolution makes it ideally suited for such searches.

“Estimating the abundance and characteristic properties of sources at early times is particularly important in understanding how the universe reionized itself, thus ending the Dark Ages,” said Mike Santos, a former Caltech graduate student, now a postdoctoral researcher at the Institute of Astronomy, Cambridge, UK. “The cosmic lens has given us a first glimpse into this important epoch. We are now eager to learn more by finding further examples, although it will no doubt be challenging.”

“We are looking at the first evidence of our ancestors on the evolutionary tree of the entire universe,” said Dr. Frederic Chaffee, director of the W. M. Keck Observatory, home to the twin 10-meter Keck telescopes that confirmed the discovery. “Telescopes are virtual time machines, allowing our astronomers to look back to the early history of the cosmos, and these marvelous observations are of the earliest time yet.”

The Caltech team reporting on the discovery consists of Drs. Jean-Paul Kneib, Richard S. Ellis, Michael R. Santos and Johan Richard. Drs. Kneib and Richard also serve the Observatoire Midi-Pyrenees of Toulouse, France. Dr. Santos also represents the Institute of Astronomy, Cambridge, UK.

Public funding for this project was provided in part by NASA GSRP grant NGT5-50339 and NASA STScI grant HST-GO-09452.01-A.

The W. M. Keck Observatory is managed by the California Association for Research in Astronomy (CARA), a scientific partnership among the California Institute of Technology (Caltech), the University of California, and the National Aeronautics and Space Administration (NASA). The Space Telescope Science Institute (STScI) is operated by the Association of Universities for Research in Astronomy, Inc. (AURA), for NASA, under contract with the Goddard Space Flight Center, Greenbelt, MD. The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency (ESA).

Original Source: Hubble News Release

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