Nancy Atkinson, Author at Universe Today

November 4, 2008December 24, 2015 by Nancy Atkinson

5 Years At Mars: The Best of Mars Express

Water ice in a North Pole crater. Credit: ESA/DLR/FU Berlin (G. Neukum).

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In December, the Mars Express spacecraft will celebrate the fifth anniversary of its arrival at Mars. In observation of this milestone the German Aerospace Center DLR has put together a collection of some of the best images from the High-Resolution Stereo Camera (HRSC), the main camera on board the spacecraft. The stunning, high resolution images this instrument has produced of Mars’ surface are nothing short of jaw dropping, and they have provided new perspectives and new discoveries about our neighboring planet. One of the iconic images from Mars Express is the image above of water ice inside a crater near Mars North Pole.

And here’s more from The Best of Mars Express:

Echus Chasma mosaic. Credits: ESA/DLR/ FU Berlin (G. Neukum)

My personal favorite is the image above of Echus Chasma, located in the Lunae Planum high plateau, north of Valles Marineris the ‘Grand Canyon’ of Mars. It doesn’t take much imagination to consider the possibility that once, gigantic water falls may have plunged over these 4,000 meter high cliffs on to the valley floor. See more of Echus Chasma here.

Here’a another of my favorites, this perspective color view of Coprates Chasma and the “Grabenkette” (a chain of depressions or rifts in Mars’ surface) Coprates Catena in an eastern section of Valles Marineris.

The ability of the HRSC to provide “perspective” views — images that are not just straight down camera shots — are what sets the Mars Express mission apart from all the other orbiting spacecraft. When seen in full resolution (please, go download the biggie image here) these 3-D perspective views, are mind blowing!

In March of this year, Ian wrote about these high resolution and 3-D images from Hebes Chasma, one of the deepest canyons on Mars, so see more images there, along with links to additional images and information.

Hebes Chasma Credit: ESA/DLR/FU Berlin (G. Neukum).

The HRSC is imaging the entire planet in full color, 3-D and with a resolution of about 10 meters. Selected areas will be imaged at two-meter resolution. One of the camera’s greatest strengths is he unprecedented pointing accuracy achieved by combining images at the two different resolutions. Another is its ability for 3-D imaging which reveals the topography of Mars in full color.

Mars North Pole. Credit: ESA/DLR FU Berlin (G. Neukum)

Here’s another look at Mars north arctic region, with water ice visible in Chasma Boreale.

Below is a view of Aureum Chaos, located in the eastern part of Valles Marineris. This “chaotic” landscape is dominated by randomly oriented, large-scale mesas and knobs that are heavily eroded. These mesas range from a few kilometres to tens of kilometers wide.

Perspective colour view of Aureum Chaos, northerly direction. Credit: ESA/DLR/FU Berlin (G. Neukum).

For a little more history on Mars Express, the spacecraft was launched on June 2, 2003 from Baikonur Cosmodrome on a Soyuz-Fregat rocket. The goal of Mars Express is to search for water and the possibility of Martian life. Mars Express is a European Space Agency (ESA) mission to the Red Planet involving a consortium of countries (primarily France, Germany, Great Britain, Ireland, Italy, Japan, the Netherlands, Norway, Russia, Sweden, Spain, and the United States). The mission consisted of the orbiter and the Beagle lander, which unfortunately crash landed on Christmas Day 2003. Mars Express is currently in its second mission extension, which goes until May 2009.

Phobos from Mars Express. Credit: ESA/DLR/FU Berlin (G. Neukum).

And finally, Mars Express not only takes images the surface of the Red Planet, but also of Mars’ moon Phobos. On July 23 of this year, the spacecraft flew only 93 kilometers from Mars’ moon Phobos, and took the most detailed images ever of the small, irregular moon. Read more about the flyby here.

That’s just a taste of all the wonderful images taken in the last five years by Mars Express. Check out more images at the DLR site.

Source: DLR

November 3, 2008December 24, 2015 by Nancy Atkinson

Rover Sand Traps Provide Clues on Mars Climate

Opportunity's self portrait while stuck in the sand in 2005. Credit: NASA/JP

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If you watched the “Five Years on Mars” documentary on the National Geographic channel about the Mars Exploration Rovers, you probably saw how both rovers have gotten stuck in some of the small sand dunes on Mars surface. These dune fields on Mars are a bit of a mystery to planetary geologists, and in fact, there is nothing like them on Earth. The fields of rippled sand on Mars, called Transverse Aeolian Ridges (TARs), are found over large areas across Mars. The dunes themselves are smaller than the gigantic dunes also found on Mars, but the fields are bigger than any sand ripple fields found on Earth. TARs hold clues to past and present climate processes, and since they can be death traps for rovers, scientists want to know more about these unusual features.

TARS are formed by the wind. If you frequently peruse the website for the HiRISE Camera on the Mars Reconnaissance Orbiter, you’ll see the word “aeolian” quite often in science themes and descriptions. Aeolian refers to any phenomena involving air movement.

TARS in the northern lowlands on Mars, as seen by HiRISE. Credit: NASA/JPL/U of AZ

The ridges assume many shapes, such as simple ripples, forked ripples, snake-like sinuous waves, barchan-like (crescent-shaped) forms or complex, overlapping networks.

In 2005, the Opportunity rover got stuck in a small dune, called Purgatory Dune for six weeks with its wheels firmly mired in what planetary geologists believe was a small TAR. After the rover was finally freed, from images the rover took of the surrounding area, mission scientists noticed they were surrounded by dunes. (See this link for movies of the rover wheels turning in the sand.) They had to carefully drive around all the dunes, which slowed the progress down considerably. So it’s important to know where TARs are located to avoid landing among them on future rover missions.

One of the people studying TARs is Matt Balme, a research scientist with the the Planetary Science Institute. Balme and his colleagues have conducted a pole-to-pole planet survey of more than 10,000 images taken by the Mars Orbiter Camera, which was (is) on board the Mars Global Surveyor spacecraft.

Here’s what they found about TARs:

-They are more common in the southern hemisphere than in the northern.

-They are found in an equatorial belt between 30 degrees north and 30 degrees south latitude.

-They exist in two distinct environments: near layered terrain or adjacent to Large Dark Dunes (LLDs). Those adjacent to dunes have formed recently, while those near layered terrain are millions of years old.

-They are abundant in the Meridiani Planum region and in southern-latitude craters.

The Opportunity rover’s TAR encounter provided additional data, showing that at least that TAR was composed of an outer layer of granule-sized material ranging from about 2mm to 5 mm in diameter, Balme said. Beneath this was a mixed mass of fine and coarse particles.

Opportunity looks back at Purgatory Dune after escape. See the other dunes in the surrounding area. Credit: NASA/JPL

TARs need two things to form, Balme explained: a supply of sediment and strong winds. The sediment requirement helps explain why they’re found near dunes and layered terrain and why they’re confined to a central belt around the planet, Balme said.

“My theory is that the very young TARs are found near the Large Dark Dunes, which are also very young, because the sand blowing off the dunes provides the energy needed to form TARs,” Balme said. “Meanwhile you have areas near layered landforms that used to have active sediment transport, but no longer. This shows a dynamic environment that has changed, and we might be able to use TARs as paleo markers to help decipher ancient climates.”

Current Martian circulation models don’t provide much evidence that wind patterns and atmospheric densities on Mars were significantly different in the past than from what they are today. “But I think the geology we are seeing suggests that there might have been different patterns and densities,” Balme said. “The observations we’re getting now from Mars Global Surveyor and the HiRISE camera are giving us really good data to drive the models.”

Although Blame and his team have discovered much about TARs, they still don’t know what materials compose the various TAR fields or why they’re seeing these large features on Mars but not on Earth.

“Over the next couple of years we should be seeing many more images from HiRISE that can give us more information, for example, about the heights versus spacing and whether TARs have more in common with dunes or the ripple fields found on Earth,” Balme said. “And they could provide insights into present and past climate patterns as we learn more about them and use that data to help drive general circulation models.”

Source: Planetary Science Institute

November 3, 2008December 24, 2015 by Nancy Atkinson

Phoenix Lander Weak But Responsive

The view from Phoenix. Credit: NASA/JPL/Caltech/U of AZ

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After re-establishing communications with the Phoenix Mars Lander late last week, engineers have been able to communicate each day with the weakening spacecraft through relays with the Mars orbiters. But each day, Phoenix runs out of power by late afternoon or early evening. It is able to reawaken the next day after its solar arrays catch morning sunlight. Via Twitter, the lander said it is resting a lot, and hoping to get some strength back in order to do some more science. But each day the amount of time the sun is above the horizon at Mars north polar region diminishes. Additionally, dust raised by a storm last week continues to block some of the sunshine.

“This is exactly the scenario we expected for the mission’s final phase, though the dust storm brought it a couple weeks sooner than we had hoped,” said Phoenix Project Manager Barry Goldstein of NASA’s Jet Propulsion Laboratory, Pasadena, Calif. “We will be trying to gain some additional science during however many days we have left. Any day could be our last.”

Mission controllers at JPL and Lockheed Martin Space Systems are attempting this week to upload commands to be stored in the lander’s flash memory for science activities to be conducted when the lander wakes up each day.

“Weather observations are our top priority now,” said Phoenix Principal Investigator Peter Smith. “If there’s enough energy, we will try to get readings from the conductivity probe that has been inserted into the soil, and possibly some images to assess frost buildup.”

Source: JPL

November 3, 2008December 24, 2015 by Nancy Atkinson

Mars Methane Mystery Still Beckons

Discoveries of methane on Mars suggest it is actively being replenished. (Image: ESA/DLR/FU Berlin, G Neukum)

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We’ve known about the methane in Mars’ atmosphere for over four years now. But we don’t know where it is coming from. On Earth, methane is produced from biological agents: rotting vegetation or flatulence from large animals like cows. But, of course, with our extensive explorations of Mars with rovers and high-resolution orbiting cameras, we’re fairly sure there are no Martian bovine equivalents chewing cud from the foliage on the Red Planet. Even if life existed in the past on Mars, methane is broken down quite quickly by sunlight, and scientists have calculated that methane should only exist for a few hundred years in the Martian atmosphere. The only possibility is that somehow, either chemically or biologically, the methane is being replaced on a regular basis. And now, two recent reports outlining separate discoveries on Mars make this methane mystery even more intriguing.

Methane was discovered on Mars by three independent groups in 2003 – 2004. One detection was made using the Mars Express spacecraft, another used observations from the Keck II and Gemini South telescopes, and the third used the Canada-France-Hawaii telescope.

And the mystery of how methane on Mars is being replenished has scientists continuing their observations in an effort to understand what’s happening on Mars. Michael Mumma of NASA’s Goddard Space Flight Center in Greenbelt, Maryland was one of the original methane discoverers. Observations he and his team have made over the last four years show methane is not spread evenly around Mars, but concentrated in a few “hotspots.” They have seen that methane clouds spanning hundreds of kilometers form over these hotspots and dissipate within a year – much shorter than the 300 – 600 years it was thought to take for atmospheric methane to be destroyed by sunlight. If methane is being destroyed so quickly, it also must be created at far higher rates than previously thought. Mumma reported these results at a planetary science conference last month.

Nili Fossae region on Mars, a methane "hotspot: Credit: NASA/JPL/U of AZ

One of the hotspots is Nili Fossae a fissure that has been eroded and partly filled in by sediments and clay-rich ejecta from a nearby crater. Could a living ecosystem be hidden here under the Martian surface? On Earth, subterranean microbes survive without sunlight, free oxygen, or contact with the surface. Additionally, the prospect becomes more intriguing when it is known on Earth, most deep-surface microbes are primitive, single-celled organisms that power their metabolism with chemical energy from their environment. These microbes are called “methanogens” because they make methane as a waste product.

Nili Fossae is one of the possible landing sites for the Mars Science Laboratory, the next generation of rover currently set to head off the Red Planet next year.

A pair of pit caves on Mars. Could life exist inside? Credit: NASA/JPL/University of Arizona

But astrobiologists aren’t ruling out the possibility of some type of ongoing chemical process on Mars, which could be producing the methane. But even this is intriguing, because it means there are active processes going on inside Mars. One idea proposed in a recent paper is that methane clathrates are near the Martian surface, and are constantly releasing small amounts of methane as temperatures and pressure near the surface change.
Methane clathrates are solid forms of water that contain a large amount of methane within its crystal structure.

Caroline Thomas and her colleagues at the Universite de Franche-Comte say the clathrates could only exist near the surface of Mars if the atmosphere had once been methane rich. Otherwise the clathrates could never have formed. One possibility is that the atmosphere was once temporarily enriched by a comet impact. Also, the discovery of gray crystalline hematite deposits on the surface could be a proof of an early methane-rich Martian atmosphere.

Otherwise, the researchers say, the only other possibility is a biological source.

“Our results show that methane enriched clathrate hydrates could be stable in the subsurface of Mars only if a primitive CH4-rich atmosphere has existed or if a subsurface source of CH4 has been (or is still) present,” the researchers write.

So what does all this mean? The Mars Science Laboratory rover might have the ability to find out, or at least bring us closer to solving this mystery. Otherwise it will take a fairly large breakthrough from the other spacecraft and telescopes observing Mars. But it’s possible we might not fully understand why Mars has methane until humans actually go there themselves to find out.

Sources: arXiv, arXiv blog, New Scientist, Nature

November 3, 2008December 24, 2015 by Nancy Atkinson

Cassini’s ‘Skeet Shoot’ of Enceladus Produces Spectacular Images

Baghdad Sulcus on Enceladus. Credit: CICLOPS

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The Cassini spacecraft performed another ‘skeet shoot’ over Enceladus’ south pole on Friday, and returned some absolutely stunning images. Or as Carolyn Porco, the imaging team leader for the spacecraft said, “a bounty of positively glorious views of one of the most fabulous places in the solar system.” The resolution of the mosaic shown here is just 12.3 meters per pixel! Visible are large house-sized boulders, and the deep “tiger stripes” from which the plumes of material are being produced. One source of the jets producing the plumes is identified in the upper right on this image. Enjoy these great images now because the next flyby of Enceladus won’t be for another year. And at that time, the sun won’t be shining as predominantly on moon’s south pole, so next year the view of this region of Enceladus will be much dimmer. Here’s more…

This Cassini image was the first and highest resolution ‘skeet shoot’ narrow angle image captured during the October 31st flyby of Enceladus.

The image was taken with the Cassini spacecraft narrow-angle camera on October 31, 2008 at a distance of approximately 1691 kilometers (1056 miles) from Enceladus and at a Sun-Enceladus-spacecraft, or phase, angle of 78 degrees. Image scale is 9 meters (30 feet).

Here’s the 8th image from the flyby using the narrow angle camera The source region for jets II and III are identified. To identify jet source locations on the surface, imaging scientists carefully measured the locations and orientations of individual jets observed along the moon’s limb in Cassini images taken from multiple viewing angles. For each jet measurement, the researchers then computed a curve, or ground track, on the surface of Enceladus along which that jet might lie. The researchers were able to isolate eight areas as jet sources.

The image was taken with the Cassini spacecraft narrow-angle camera at a distance of approximately 5568 kilometers (3480 miles) from Enceladus and at a Sun-Enceladus-spacecraft, or phase, angle of 75 degrees. Image scale is 32 meters (105 feet) per pixel.

Sources: CICLOPS (here and here)

November 3, 2008April 26, 2016 by Nancy Atkinson

Chandrayaan-1 Tests Out Camera; Target: Earth

Image of Earth from Chandrayaan-1. Credit: ISRO

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While the Chandrayaan-1 spacecraft wends its way to the Moon with gradually longer elliptical loops around the Earth, mission scientists decided to test out the main camera on board, the Terrain Mapping camera (TMC). The camera snapped this picture of Earth on October 29, 2008, at a distance of 70,000 km, showing Australia. If you’re having a hard time making out the image, it might be because the image is flipped, as though looking at it in a mirror. Emily Lakdawalla over at the Planetary Society blog figured this out and has flipped the image for us (see below). Why is the original image backwards? Emily explains, “Data doesn’t come down from spacecraft in familiar formats like JPEG or TIFF; it’s a stream of ones and zeroes, with a format unique to the science instrument, and scientists and engineers write their own software for translating that into raw image data. There are varying conventions for whether bits are written right or left, and if you take that raw image data and open it up in a piece of off-the-shelf image processing software, the image might be backwards.” As Emily says, the error is not really important. The image is beautiful, and gives reason for great anticipation of the first images it will return of the moon.

In the meantime, there’s another, closer image of Earth from 9,000 km, too…

Here’s the image from 9,000 km:

Chandrayaan-1: Earth from 9,000 km. Credit: ISRO

TMC is one of the eleven scientific instruments on Chandrayaan-1. The camera can take black and white pictures of an object by recording the visible light reflected from it. The instrument has a resolution of about 5 metres.

And here’s Emily’s “visually correct” version of the original Chandrayaan-1 image:

Chandrayaan-1 will execute one more maneuver to raise its orbit, and send the spacecraft to the vicinity of the moon at a distance of about 384,000 km from the Earth. Once the Chandrayaan-1 spacecraft reaches the vicinity of the Moon, the spacecraft will be slowed sufficiently to enable the gravity of the moon capture it into an elliptical orbit. The spacecraft will make observations from the initial orbit, and then the orbit will be lowered a 100 km circular polar orbit. Following this, the Moon Impact Probe (MIP) will be ejected, impacting the lunar surface. Then the main mission will commensce, with Chandrayaan-1 exploring the moon from orbit with its array of instruments for two years.

More about Chandrayaan-1.

Source: ISRO

October 31, 2008December 24, 2015 by Nancy Atkinson

TV Alert: Five Years on Mars

On Sunday evening Nov. 2, at 7 pm CST,(in the US; check your local listings) the National Geographic channel will be showing a special documentary on the Mars Exploration Rovers. It’s called “Five Years on Mars,” and dramatizes the trials and tribulations of the rovers Spirit and Opportunity and highlights new scientific information on the planet’s geology and water history.

If you saw the “Mars: Dead or Alive” and “Welcome to Mars” shows, this one should be even better. The show will feature photo-realistic animation based on the actual landscape as captured by the rovers’ cameras, and interviews with MER PI Steve Squyres and others on the rover team.

Check out the National Geographic channel’s website that has some very spiffy downloadable wallpapers (like the one above), videos and other information about the show and about the rovers and their mission. Robert Pearlman at CollectSPACE.com also has a great overview of the show and an interview with Steve Squyres.

When the landed on Mars in 2004, they were expected to collect data over 90 Martian days, or “sols.” But ninety days have stretched into almost five years, and a short-term science mission searching for evidence of ancient water has turned into one of the greatest adventures of the space age. The rovers have trekked miles across hostile plains, climbed mountains, ventured in and out of deep craters, gotten stuck in sand dunes, and survived dust storms and mechanical failures.

Mark Davis, who also served as writer/producer/director of the award winning “Mars Dead or Alive” and “Welcome to Mars,” teams with legendary animator Dan Maas (IMAX “Roving Mars”)

Don’t miss it!

October 31, 2008December 24, 2015 by Nancy Atkinson

Chandra Telescope Searches for Antimatter

The Bullet Cluster is another of several gigantic galaxy clusters challenging the Lambda-cold dark matter theory of struc ture formation in the early Universe. Credit: X-ray: NASA/CXC/CfA/M.Markevitch et al.; Optical: NASA/STScI; Magellan/U.Arizona/D.Clowe et al.

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Say the word “antimatter” and immediately people think of science fiction – anti-universes, fuel for the Enterprise’s warp-speed engines and so forth. But Captain, we can’t change the laws of physics; antimatter is the real deal. Antimatter is made up of elementary particles, each of which has the same mass as their corresponding matter counterparts –protons, neutrons and electrons — but the opposite charges and magnetic properties. When matter and antimatter particles collide, they annihilate each other and produce energy according to Einstein’s famous equation, E=mc2. But antimatter isn’t something that’s available on every corner drugstore (and neither is plutonium, to continue with the movie theme) and there’s not very much of it around, so it seems. But, according to theory, it wasn’t always that way, and scientists are using the Chandra X-ray Observatory to hunt for evidence of antimatter that was present in the very early universe. And it’s not an easy job…

According to the Big Bang model, the Universe was awash in particles of both matter and antimatter shortly after the Big Bang. Most of this material annihilated, but because there was slightly more matter than antimatter – less than one part per billion – only matter was left behind, at least in the local Universe.

Trace amounts of antimatter are believed to be produced by powerful phenomena such as relativistic jets powered by black holes and pulsars, but no evidence has yet been found for antimatter remaining from the infant Universe.

How could any primordial antimatter have survived? Just after the Big Bang there was believed to be an extraordinary period, called inflation, when the Universe expanded exponentially in just a fraction of a second.

“If clumps of matter and antimatter existed next to each other before inflation, they may now be separated by more than the scale of the observable Universe, so we would never see them meet,” said Gary Steigman of The Ohio State University, who conducted the study. “But, they might be separated on smaller scales, such as those of superclusters or clusters, which is a much more interesting possibility.”

Illustration of Antimatter/Matter Annihilation. (NASA/CXC/M. Weiss)

In that case, collisions between two galaxy clusters, the largest gravitationally-bound structures in the Universe, might show evidence for antimatter. X-ray emission shows how much hot gas is involved in such a collision. If some of the gas from either cluster has particles of antimatter, then there will be annihilation and the X-rays will be accompanied by gamma rays.

Steigman used data obtained by Chandra and now de-orbited Compton Gamma Ray Observatory to study the Bullet Cluster, where two large clusters of galaxies have crashed into one another at extremely high velocities. At a relatively close distance and with a favorable side-on orientation as viewed from Earth, the Bullet Cluster provides an excellent test site to search for the signal for antimatter.

Check out this very nifty animation of galaxy clusters crashing into each other.

“This is the largest scale over which this test for antimatter has ever been done,” said Steigman, whose paper was published in the Journal of Cosmology and Astroparticle Physics. “I’m looking to see if there could be any clusters of galaxies which are made of large amounts of antimatter.”

The observed amount of X-rays from Chandra and the non-detection of gamma rays from the Compton data show that the antimatter fraction in the Bullet Cluster is less than three parts per million. Moreover, simulations of the Bullet Cluster merger show that these results rule out any significant amounts of antimatter over scales of about 65 million light years, an estimate of the original separation of the two colliding clusters.

“The collision of matter and antimatter is the most efficient process for generating energy in the Universe, but it just may not happen on very large scales,” said Steigman. “But, I’m not giving up yet as I’m planning to look at other colliding galaxy clusters that have recently been discovered.”

Finding antimatter in the Universe might tell scientists about how long the period of inflation lasted. “Success in this experiment, although a long shot, would teach us a lot about the earliest stages of the Universe,” said Steigman.

Tighter constraints have been placed by Steigman on the presence of antimatter on smaller scales by looking at single galaxy clusters that do not involve such large, recent collisions.

Source: Chandra/Harvard

October 31, 2008December 24, 2015 by Nancy Atkinson

GALEX Spies a Ghost — And It’s Alive!

The Ghost of Mirach. Image credit: NASA/JPL-Caltech/DSS

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Halloween means its time for ghost stories and here’s a mysterious astronomical story about the “Ghost of Mirach.” When viewed in visible light, as in the picture above on the left, the galaxy called NGC 404 appears as just a white blob. Mirach is a red giant star that looms large in visible light, hiding NGC 404 in its glare, and therefore was nicknamed “The Ghost of Mirach” But when the Galaxy Evolution Explorer (GALEX) spied the galaxy in ultraviolet light, a spooky ring materialized and the region came to “life.” This ring, seen in blue in the picture on the right, contains new stars — a surprise considering that the galaxy was previously thought to be dead. “We thought this celestial ghost was essentially dead, but we’ve been able to show that it has an extended ring of new stars. The galaxy has a hybrid character in which the well-known, very old stellar population tells only part of the story,” said David Thilker of Johns Hopkins University in Baltimore. “It’s like the living dead.”

Oooh, spooky!

The eerie creature, called NGC 404, is a type of galaxy known as “lenticular.” Lenticular galaxies are disk-shaped, with little ongoing star formation and no spiral arms. NGC 404 is the nearest example of a lenticular galaxy, and therefore of great interest. But, usually it lies hidden in the glare from a red giant star Mirach.

Thilker and members of the Galaxy Evolution Explorer team spotted the Ghost of Mirach in images taken during the space telescope’s all-sky survey, where it is scanning the entire visible sky in ultraviolet light, a job never before accomplished.

Long exposure observations of this region show that the NGC 404 is surrounded by a clumpy, never-before-seen ring of stars.

What is this mysterious ultraviolet ring doing around an otherwise nondescript lenticular galaxy? As it turns out, previous imaging with the National Science Foundation’s Very Large Array radio telescope in New Mexico had discovered a gaseous ring of hydrogen that matches the ultraviolet ring observed by the Galaxy Evolution Explorer. The authors of this Very Large Array study attributed the gas ring to a violent collision between NGC 404 and a small neighboring galaxy 900 million years ago.

The ultraviolet observations demonstrate that, when the hydrogen from the collision settled into the plane of the lenticular galaxy, stars began to form in a ghostly ring. Young, relatively hot stars forming in stellar clusters sprinkled throughout NGC 404’s ring give off the ultraviolet light that the Galaxy Evolution Explorer was able to see.

“Before the Galaxy Evolution Explorer image, NGC 404 was thought to contain only very old and evolved red stars distributed in a smooth elliptical shape, suggesting a galaxy well into its old age and no longer evolving significantly,” said Mark Seibert of the Observatories of the Carnegie Institution of Washington in Pasadena, Calif. “Now we see it has come back to life, to grow once again.”

“The Ghost of Mirach has been lucky enough to get a new lease on life through the rejuvenating, chance merger with its dwarf companion,” added Thilker.

The findings indicate that the evolution of lenticular galaxies might not yet be complete. They may, in fact, continue to form stars in a slow, piecemeal fashion as they suck the raw, gaseous material for stars from small, neighboring galaxies. It seems the Ghost of Mirach might act more like a vampire than a ghost.

The fields of view are identical in both pictures, and spans 55,000 light years across. The Ghost of Mirach is located 11 million light-years from Earth. The star Mirach is very close in comparison — it is only 200 light-years away and is visible with the naked eye.

Source: NASA

October 30, 2008December 24, 2015 by Nancy Atkinson

Phoenix Not Responding to Communications

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Update: 10/31: Phoenix communicated with NASA’s Mars Odyssey orbiter late Thursday. The communication reinforced a diagnosis that the spacecraft is in a precautionary mode triggered by low energy. Mission engineers are assessing the lander’s condition and steps necessary for returning to science operations.

The Phoenix Lander is not responding to attempts to communicate with it. Earlier today, we reported that Phoenix had gone into safe mode. The lander experienced a low-power fault in the electrical system due to the reduction of solar-electric power to shorter daylight hours and a dust storm, as well as extremely cold weather. Engineers for the mission were able to send a command to restart a battery that had shut off, and were hopeful that further communications would resume without incident. However, Phoenix did not respond to one of the Mars orbiter’s attempt to communicate with it Wednesday night and Thursday morning.

I don’t know about the rest of you, but I’m not ready to say goodbye to Phoenix quite yet…

Mission controllers believe the most likely situation to be that declining power has triggered a pre-set precautionary behavior of waking up for only about two hours per day to listen for an orbiter’s hailing signal. If that is the case, the wake-sleep cycling would have begun at an unknown time when batteries became depleted.

“We will be coordinating with the orbiter teams to hail Phoenix as often as feasible to catch the time when it can respond,” said Phoenix Project Manager Barry Goldstein at NASA’s Jet Propulsion Laboratory, Pasadena, Calif. “If we can reestablish communication, we can begin to get the spacecraft back in condition to resume science. In the best case, if weather cooperates, that would take the better part of a week.”

Stay tuned…

Source: JPL