Posted on by Nancy Atkinson

Dark Matter Halos? How About Disks, Too

A composite image shows a dark matter disk in red. From images in the Two Micron All Sky Survey. Credit: Credit: J. Read & O. Agertz.

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Scientists are trying to understand the invisible and hypothetical ‘dark matter’ – the stuff that we know exists by inference of its gravitational influence on the matter we can see. The most common held notion of dark matter is that it exists in ‘halos’ or clumps that surround galaxies. But a new study predicts that galaxies like our own Milky Way, also contain a disk of dark matter. Using the results of a supercomputer simulation, scientists from the University of Zurich and the University of Central Lancashire say that if dark matter in fact resides as a disk within a galaxy, it could allow physicists to directly detect and identify the nature of dark matter for the first time.

Physicists believe dark matter makes up 22% of the mass of the Universe (compared with the 4% of normal matter and 74% comprising the mysterious ‘dark energy’). But, despite its pervasive influence, no-one is sure what dark matter consists of.

This ‘standard’ theory of dark matter is based on supercomputer simulations that model the gravitational influence of the dark matter alone. The new work includes the gravitational influence of the stars and gas that also make up our Galaxy.

Stars and gas are thought to have settled into disks very early on in the life of the Universe and this affected how smaller dark matter halos formed. The team’s results suggest that most lumps of dark matter in our locality merged to form a halo around the Milky Way. But the largest lumps were preferentially dragged towards the galactic disk and were then torn apart, creating a disk of dark matter within our Galaxy.

“The dark disk only has about half of the density of the dark matter halo, which is why no one has spotted it before,” said lead author Justin Read. “However, despite its low density, if the disk exists it has dramatic implications for the detection of dark matter here on Earth.”

The Earth and Sun move at some 220 kilometres per second along a nearly circular orbit about the center of our Galaxy. Since the dark matter halo does not rotate, from an Earth-based perspective it feels as if we have a ‘wind’ of dark matter flowing towards us at great speed. By contrast, the ‘wind’ from the dark disk is much slower than from the halo because the disk co-rotates with the Earth.

“It’s like sitting in your car on the highway moving at a hundred kilometres an hour”, said team member Dr. Victor Debattista. “It feels like all of the other cars are stationary because they are moving at the same speed.”

This abundance of low-speed dark matter particles, the science team says, could be a real boon for researchers because they are more likely to excite a response in dark matter detectors than fast-moving particles. “Current detectors cannot distinguish these slow moving particles from other background ‘noise’,” said Prof. Laura Baudis, a collaborator at the University of Zurich and one of the lead investigators for the XENON direct detection experiment, which is located at the Gran Sasso Underground Laboratory in Italy. “But the XENON100 detector that we are turning on right now is much more sensitive. For many popular dark matter particle candidates, it will be able to see something if it’s there.”

If so, its possible that the dark disk could be directly detected in the very near future.

Sources: Monthly Notices paper, Royal Astronomical Society

Posted on by Nancy Atkinson

Newest Mission to Mars: MAVEN

Why do planets like Mars have a different atmosphere than Earth? Credit: NASA

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Did Mars once have a thick atmosphere? Could the climate on the Red Planet have supported water and possibly life in the past? These are the questions NASA hopes to answer in great detail with the newest orbiter mission to Mars. Called the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft, the $485 million mission is scheduled for launch in late 2013. MAVEN is part of the Mars Scout Program, which is designed to send a series of small, low-cost, principal investigator-led missions to the Red Planet. The Phoenix Mars Lander was the first spacecraft selected in this program. “This mission will provide the first direct measurements ever taken to address key scientific questions about Mars’ evolution,” said Doug McCuistion, director of the Mars Exploration Program at NASA Headquarters in Washington.

Evidence from orbit and the planet’s surface points to a once denser atmosphere on Mars that supported the presence of liquid water on the surface. As part of a dramatic climate change, most of the Martian atmosphere was lost. MAVEN will make definitive scientific measurements of present-day atmospheric loss that will offer clues about the planet’s history.

“The loss of Mars’ atmosphere has been an ongoing mystery,” McCuistion said. “MAVEN will help us solve it.”

The science team will be led from the University of Colorado at Boulder, and its Laboratory for Atmospheric and Space Physics. The principal investigator for the mission is Bruce Jakosky from UC Boulder. “We are absolutely thrilled about this announcement,” said Jakosky. “We have an outstanding mission that will obtain fundamental science results for Mars. We have a great team and we are ready to go.”

Artist depiction of the MAVEN spacecraft. Credit: NASA
Artist depiction of the MAVEN spacecraft. Credit: NASA

Lockheed Martin of Littleton, Colo., will build the spacecraft based on designs from NASA’s Mars Reconnaissance Orbiter and 2001 Mars Odyssey missions.
MAVEN was evaluated to have the best science value and lowest implementation risk from 20 mission investigation proposals submitted in response to a NASA Announcement of Opportunity in August 2006.

After arriving at Mars in the fall of 2014, MAVEN will use its propulsion system to enter an elliptical orbit ranging 90 to 3,870 miles above the planet. The spacecraft’s eight science instruments will take measurements during a full Earth year, which is roughly equivalent to half of a Martian year.
MAVEN’s instrument suites include a remote sensing package that will determine global characteristics of the upper atmosphere, and the spacecraft will dip to an altitude of 80 miles above the planet. A particles and fields payload contains six instruments that will characterize the solar wind, upper atmosphere and the ionosphere – a layer of charged particles very high in the Martian atmosphere.

The third instrument suite, a Neutral Gas and Ion Mass Spectrometer will measure the composition and isotopes of neutral and charged forms of gases in the Martian atmosphere

During and after its primary science mission, the spacecraft may be used to provide communications relay support for robotic missions on the Martian surface.

More information on MAVEN.

Sources: NASA, UC Boulder

Posted on by Nancy Atkinson

NASA Weathers Hurricane; May Impact Hubble Mission

Trees down on a street in Houston, Texas. Credit: Houston Chronicle, DJ Sherm

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NASA’s Johnson Space Center in Houston weathered Hurricane Ike fairly well, but damage to some buildings, including the roof of the Mission Control Center will need to be repaired before the facility is ready to open for normal operations. A space agency spokesman said it could be late this week or even sometime during the week of Sept. 21 before all the buildings would reopen. The 16,500 employees at JSC will also need to access and repair any damage to their own homes as well. JSC lost power, but essential systems were powered with generators. Controller for the International Space Station established a temporary control center at a hotel inland in Austin, Texas before Johnson was closed on Thursday. Working with another team at NASA’s Marshall Space Flight Center in Huntsville, Alabama, controllers are trying to fill in until Mission Control can re-open.

While there was some standing water, JSC was not affected by Ike’s Galveston Bay surge, but high winds caused roof damage and downed trees. Repairs and cleanup were under way on Sunday.
Meanwhile, the space agency has not assessed the impact of the storm on plans for the scheduled October 10 launch of the shuttle Atlantis on a mission to overhaul the Hubble Space Telescope and the November 12 date for launching shuttle Endeavour on a space station assembly mission, said David Waters, spokesman for United Space Alliance, NASA’s shuttle prime contractor.

Additionally, a resupply ship’s docking with the ISS was delayed, and it waits on orbit near the station. U.S. and Russian flight controllers hope to dock the unmanned Progress supply ship Wednesday at 2:43 p.m. EDT. The cargo craft was launched from the Baikonur Cosmodrome in Kazakhstan last Wednesday and originally was scheduled to dock Friday.

Sources: Houston Chronicle, Spaceflightnow.com

Posted on by Nancy Atkinson

First Picture of Likely Planet Around a Sun-Like Star

The small dot above the star 1RSX J160929.1-210524 is a likely ~8 Jupiter-mass companion. Credit: Gemini Observatory

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Astronomers have unveiled what is likely the first picture of a planet around a normal star similar to the Sun. Using the Gemini North telescope on Mauna Kea in Hawaii, astronomers from the University of Toronto imaged the young star 1RXS J160929.1-210524, which lies about 500 light-years from Earth and a candidate companion of that star. They also obtained spectra to confirm the nature of the companion, which has a mass about eight times that of Jupiter, and lies roughly 330 times the Earth-Sun distance away from its star. For comparison, the most distant planet in our solar system, Neptune, orbits the Sun at only about 30 times the Earth-Sun distance. The parent star is similar in mass to the Sun, but is much younger. “This is the first time we have directly seen a planetary mass object in a likely orbit around a star like our Sun,” said David Lafrenière, lead author of a paper detailing the discovery. “If we confirm that this object is indeed gravitationally tied to the star, it will be a major step forward.”

Until now, the only planet-like bodies that have been directly imaged outside of the solar system are either free-floating in space (i.e. not found around a star), or orbit brown dwarfs, which are dim and make it easier to detect planetary-mass companions.

The existence of a planetary-mass companion so far from its parent star comes as a surprise, and poses a challenge to theoretical models of star and planet formation. “This discovery is yet another reminder of the truly remarkable diversity of worlds out there, and it’s a strong hint that nature may have more than one mechanism for producing planetary mass companions to normal stars,” said team member Ray Jayawardhana.

The team’s Gemini observations took advantage of adaptive optics technology to dramatically reduce distortions caused by turbulence in Earth’s atmosphere. The near-infrared images and spectra of the suspected planetary object indicate that it is too cool to be a star or even a more massive brown dwarf, and that it is young.

While it could be a chance alignment between the object and the young star, it will take up to two years to verify that the star and its likely planet are moving through space together. “Of course it would be premature to say that the object is definitely orbiting this star, but the evidence is extremely compelling. This will be a very intensely studied object for the next few years!” said Lafrenière.

Team member Marten van Kerkwijk described the group’s search method. “We targeted young stars so that any planetary mass object they hosted would not have had time to cool, and thus would still be relatively bright,” he said. “This is one reason we were able to see it at all.”

The Jupiter-sized body has an estimated temperature of about 1800 Kelvin (about 1500ºC), much hotter than our own Jupiter, which has a temperature of about 160 Kelvin (-110ºC), and its likely host is a young star of type K7 with an estimated mass of about 85% that of the Sun.

“This discovery certainly has us looking forward to what other surprises nature has in stock for us,” said Van Kerkwijk.

Read the team’s paper here.

Source: Gemini Observatory

Posted on by Nancy Atkinson

Lake-Effect Clouds Discovered on Titan

Map projected images of lake-effect clouds at the winter north pole of Titan from the VIMS (left, both from 27 April 2007) and ISS (right, from 24 Feb 2007, top, and 13 April 2007, bottom) imagers on board the Cassini spacecraft.

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While browsing through Cassini images of Saturn’s moon Titan, astronomer Mike Brown and some colleagues noticed a recurring pattern of clouds appearing over the frigid moon’s north pole. While a large, stable cloud has been visible in every image of Titan’s north pole obtained since its discovery, Brown noticed bright “knots or streaks” in the cloud that appeared on some images but not others, or changed in images taken hours apart. Brown thought these bright features looked similar to cumulus clouds – or even like thunderheads. But how could tropical-like thunderheads be present on a moon where surface temperatures hover around -178°C (-289°F)? Brown believes these clouds are similar to winter-time lake-effect clouds found on Earth, and are due to convection and condensation occurring in the methane and ethane lakes on Titan.

“On the Earth, lake-effect clouds occur in the winter when cold air goes over warm water (like the Great Lakes) and picks up heat and moisture and then, often, deposits it all in the form of snow on the eastern shores,” Brown told Universe Today. “On Titan the winters are so long (the north pole has been in the dark for the past ~10 years!) that the lakes retain almost no heat. But as the spring sunlight starts to hit the lakes they begin to heat up just a tiny amount and this is enough to cause little blips of evaporation and clouds.”

So, while lake-effect clouds on Earth are predominantly a winter event, on Titan, lake-effect clouds occur as spring is approaching. The clouds appear only in images taken since February 2005, as the increasing amount of sunlight has heated the liquid hydrocarbon lakes slightly and evaporation takes place. “Every time the lakes warm up just a bit, a huge dollop of evaporation occurs, which re-cools the lake, and we see a cumulus cloud pop up. The lake then has to wait for some more sunlight before it happens again,” Brown wrote in his blog.

Brown, a professor of planetary astronomy at Caltech, is known primarily for his discoveries of trans-Neptunian objects like Eris and Sedna. But he enjoys dipping his toes in the water, so to speak, in other areas as well. That includes studying the meteorology of a moon that’s over 1,200 million kilometers away. “I think it’s pretty fun,” Brown admitted.

Since spring is approaching on Titan (equinox occurs in August 2009), the cloud activity is likely to increase. Fortuitously, Cassini is scheduled to fly by Titan frequently the next few years, and Brown and his team will be keeping an eye on these lake-effect-like clouds that may have a great influence on Titan’s weather.

“When Cassini was first conceived no one even knew that clouds existed on Titan!” said Brown. “But the trick is to put a spacecraft up that has highly versatile and flexible instruments and then you’ll be able to see things even if you hadn’t anticipated them.”

Brown and his team examined the north polar clouds of Titan using data from VIMS (Visible and Infrared Mapping Spectrometer) and ISS (Imaging Science Subsystems) instruments on board the Cassini spacecraft and from adaptive optics observations from the Gemini observatory and full-disk spectroscopy of Titan from the NASA Infrared Telescope Facility (IRTF).

Titan continues to surprise planetary scientists like Brown. “I love the similarities and differences with the Earth,” he said. “Titan is the only other place that we know of that has both liquids on its surface and a thick atmosphere, so we get a chance to watch something sort of Earth-like but with some very non-terrestrial behavior.”

Source: arXiv

Posted on by Nancy Atkinson

Pluto Spacecraft Gets Brain Transplant

Artist rendition of New Horizons in the Kuiper Belt. Credit: Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute (JHUAPL/SwRI)

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Still seven years away from its rendezvous with Pluto, the New Horizons spacecraft was awoken from hibernation for the second annual checkout of all systems. The spacecraft and its team back on Earth will also undergo three months of operations as the New Horizons will make observations of Uranus, Neptune, and Pluto. But the first order of business was uploading an upgraded version of the software that runs the spacecraft’s Command and Data Handling system. “Our ‘brain transplant’ was a success,” says New Horizons Principal Investigator Alan Stern. “The new software – which guides how New Horizons carries out commands and collects and stores data – is now on the spacecraft’s main computer and operating, over a billion miles from home!”

The mission ops team at the Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Maryland, radioed the software load and the commands to start it earlier this week through NASA’s Deep Space Network of antennas to the spacecraft, now just more than 1.01 billion miles (1.62 billion kilometers) from Earth. In the next 10 days the team will beam up additional new software for both the spacecraft’s Autonomy and Guidance and Control systems.

Space Science Mission Operations Center at the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland.
Space Science Mission Operations Center at the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland.

Alice Bowman, New Horizons mission operations manager at APL, says the spacecraft and its computers are healthy. “The new software fixes a few bugs and enhances the way these systems operate, based on what we’ve learned in running the spacecraft in the nearly three years since launch,” she says. “They also configure the onboard systems to be ready to support the Pluto-Charon encounter rehearsals scheduled for next summer.”

New Horizons is more than 200 million miles beyond Saturn’s orbit and more than 11 astronomical units (1.02 billion miles) from the Sun, flying about a million miles per day toward Pluto. Annual Checkout 2 (ACO-2) continues through mid-December; follow its progress through frequent updates on the New Horizons Twitter page.

Source: New Horizons Press Release

Posted on by Nancy Atkinson

Got a Green Idea? Win $25,000

From the people that brought you the X PRIZE and the Google Lunar X PRIZE comes something new that’s a little more down to Earth. However they also say it’s crazy. But if you’re handy with a video camera, care about the environment, and are interested in winning a nice chunk of spare change, this might be up your alley. The $25,000 “What’s your crazy green idea?” Video Contest was just announced, and the X PRIZE folks are looking to find out what crazy ideas are out there that could become the next big thing for the environoment. “Before something is a breakthrough, it’s a crazy idea,” they say, and the X PRIZE Foundation is looking for your crazy green ideas to become the next X PRIZE. Here’s a video for more information:

Here are the rules:

1. Submit a 2 minute video to this group by October 31, 2008 explaining what you think should be the next Energy and Environment X PRIZE. Here’s the link.

2. The three most viable ideas will be posted on the X PRIZE website on November 15.

3. The public will be given two weeks to vote for the winner on the same site. The most creative, revolutionary idea and video will receive $25,000 and it could become the next great X PRIZE.

Be sure that your video answers the following questions:

1. What is the Grand Challenge or world-wide problem that you are trying to solve?
2. What is the specific prize idea (goal, rules, judging criteria)?
3. How will this prize lead to benefits for humanity?

Good luck!

Source: The Launch Pad

Posted on by Nancy Atkinson

Phoenix Spies – and Feels – Dust Devils

A dust devil dances in the distance from the Phoenix lander. Credit: NASA/JPL/Caltech/U of AZ

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Not only has the Phoenix Mars Lander photographed several dust devils dancing across the arctic plain this week, but sensors that monitor various atmospheric conditions around the lander detected a dip in air pressure as one of the whirlwinds passed nearby. This is the first time dust devils have been detected in Phoenix images. Scientists believe the increasing difference between daytime high temperatures (about -30C) and night lows (around -90C) is the key to the formation of the dust devils. Click here to download a dust devil movie created from the images.

The Surface Stereo Imager camera on Phoenix took 29 images of the western and southwestern horizon on Sept. 8, during mid-day hours of the lander’s 104th Martian day. The next day, after the images had been transmitted to Earth, the Phoenix science team noticed a dust devil right away.

“It was a surprise to have a dust devil so visible that it stood with just the normal processing we do,” said Mark Lemmon of Texas A&M University, College Station, lead scientist for the stereo camera. “Once we saw a couple that way, we did some additional processing and found there are dust devils in 12 of the images.”

Another image of a dust devil from Phoenix. Credit: NASA/JPL/Caltech/U of AZ
Another image of a dust devil from Phoenix. Credit: NASA/JPL/Caltech/U of AZ

At least six different dust devils appear in the images, some of them in more than one image. They range in diameter from about 2 meters (7 feet) to about 5 meters (16 feet).

The Phoenix team is not worried about any damage to the spacecraft from these swirling winds. “With the thin atmosphere on Mars, the wind loads we might experience from dust devil winds are well within the design of the vehicle,” said Ed Sedivy, Phoenix program manager at Lockheed Martin Space Systems Company, Denver, which made the spacecraft. “The lander is very rigid with the exception of the solar arrays, which once deployed, latched into position and became a tension structure.”

Phoenix monitors air pressure every day, and on the same day the camera saw dust devils, the pressure meter recorded a sharper dip than ever before. The change was still less than the daily change in air pressure from daytime to nighttime, but over a much shorter time.

“Throughout the mission, we have been detecting vortex structures that lower the pressure for 20 to 30 seconds during the middle part of the day,” said Peter Taylor of York University, Toronto, Canada, a member of the Phoenix science team. “In the last few weeks, we’ve seen the intensity increasing, and now these vortices appear to have become strong enough to pick up dust.”

The same day as the dust devils were seen, the photographed swinging of Phoenix’s telltale wind gauge indicated wind speeds exceeding 5 meters per second (11 miles per hour). Download a movie of the telltail wind gauge.

Images from spacecraft orbiting Mars had previously indicated that dust devils exist in the region where Phoenix landed.

“We expected dust devils, but we are not sure how frequently,” said Phoenix Project Scientist Leslie Tamppari of NASA’s Jet Propulsion Laboratory, Pasadena, Calif. “It could be they are rare and Phoenix got lucky. We’ll keep looking for dust devils at the Phoenix site to see if they are common or not.”

The dust devils that Phoenix has observed so far are much smaller than dust devils that NASA’s Mars Exploration Rover Spirit has photographed much closer to the equator.

Source: Phoenix news site.

Posted on by Nancy Atkinson

Satellite, ISS Images of Hurricane Ike

Hurricane Ike is bearing down on the US gulf coast, and even before landfall, is causing problems. Nearly 1 million people along the Texas coast have been ordered to evacuate, the other 3 million people in the Houston metro area have been asked not to leave, in hopes of avoiding the panic of three years ago, when evacuations ordered in advance of Hurricane Rita sent millions onto highways causing traffic jams and deadly accidents. The airports in Houston will close tomorrow, and NASA’s Johnson Space Center closed today.

Image of Ike taken from the ISS. Credit: NASA
Image of Ike taken from the ISS. Credit: NASA
Astronauts on board the International Space Station had this view of Ike from their orbital perch 220 statute miles above the Earth. (See below for a larger, close-up image.) Mission managers for the ISS have taken up residence in a hotel far inland, armed with laptops and a secure high speed internet connection in order to maintain contact with the orbiting space station. Ike is currently a Category 2 hurricane according to the National Hurricane Center, but forecasters were predicting that Ike might reach Category 3 strength in the warm waters of the Gulf prior to its projected landfall on the central Texas coastline.

TRMM (Tropical Rainfall Measuring Mission) spacecraft observed this view of Hurricane Ike on September 10, 2008 at 1745 UTC. The storm was a category 2 hurricane with sustained winds of 85 knots (97.75 mph) and a pressure reading of 958 millibars. At this time, the storm has two nearby well-defined wind maxima of roughly equal strength. There is a 17 km tower in the outer eye.

Click here for an animation from the TRMM spacecraft data.

The astronauts on board the International Space Station had this incredible view of the hurricane as it approached the Gulf Coast.

Ike was a Category 4 storm before its passage over Cuba stripped it of some of its power. It re-emerged in the Gulf of Mexico as a Category 1 storm and re-strengthened.

As of 10:00 a.m., Sept. 11, hurricane warnings are up from Morgan City Louisiana to Baffin Bay, Texas. Hurricane conditions could reach the coast within the warning area by late Friday, Sept. 12.

Ike is a Category 2 hurricane with maximum sustained winds near 100 mph. He is forecast to strengthen to a Category 3 storm before reaching the Texas coastline. Ike is moving west-northwest near 10 mph and will be near the coast late on Sept. 12, however, because Ike is large, tropical storm force winds will be felt far in advance.

Sources: NASA’s ISS Page, NASA Earth Observatory Page, The Weather Channel. Here are even more hurricane photos and hurricane images.

Posted on by Nancy Atkinson

ESA Needs a Name for Next ISS Mission

ESA Astronaut Frank DeWinne on board the ISS. Credit: ESA

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The European Space Agency needs a bang-up, attention-grabbing moniker for the next long duration European mission to the International Space Station, and they are holding a competition for the public to submit a suitable name. In May 2009, ESA astronaut Frank De Winne, of Belgium will fly to the ISS for a six month mission. ESA is holding a competition to find a name for the mission. Have any great ideas? Here are the parameters for the competition:

The name has to reflect the following aspects:

1. Europe is exploring space, and humans are explorers by nature. Europe has a legacy in exploring Earth and will live up to the expectations in exploring Space.

2. Europe has its own Columbus laboratory permanently in space on the ISS. Europe uses its Columbus laboratory on the ISS for science, technology and education for the benefit of life on Earth.

3. From space our planet looks blue because of the water. Water is the basis of life; Clean water is the basis for healthy life of all humans on Earth.

Wow, that’s a tough set of parameters. Now, here’s a few rules: (for the full rules see HERE)

1. The competition is open to all citizens of the ESA Member States (sorry US and Canada folks, you’re out of luck on this one.)

2. The proposals have to arrive in the [email protected] mailbox the latest by 18:00 CEST, 15 October 2008.

3. The proposal should be maximum of one page, with 12 pt single spacing

4. The name should be a word (or a short combination of words), not a personal name (unless it is a mythological name which has a commonly known symbolic meaning).

Again, here’s the full rules. Have fun and go for it!

Source: ESA