Posted on by Nancy Atkinson

Triple and Double Craters on Mars

Scientists working with the Mars Odyssey spacecraft say that it’s not uncommon for multiple pieces of a meteor to impact Mars close together at the same time. Here, a triple crater was formed simultaneously when three pieces of a meteor struck Mars’ surface together. When this happens, the craters that are formed overlap and the force of the impacts results in a linear wall separating the craters that form side-by-side. This image is part of a larger image swath taken by the THEMIS instrument (Thermal Emission Imaging System) on the Odyssey spacecraft. On another part of this larger image, there’s also a double crater.


This double crater appears to be different, however, from the triple crater in that the two craters were likely formed at different times. The smaller crater to the left appears older, since material from when the second, larger crater to the right was formed has been thrown into the crater on the left. The crater on the left appears more eroded and weathered, as well.

Here’s the entire image swath from Odyssey:

The Mars Odyssey spacecraft arrived at Mars on October 24, 2001, and has been mapping the surface of the Red Planet since February 2002.

Click here to see a map of Mars where these craters are located.

Original News Source: THEMIS/Mars Odyssey webpage

Posted on by Nancy Atkinson

New Type of White Dwarf Stars Discovered

Most of the stars in the universe will end their lives as white dwarfs, the class of star that’s just a remnant of the star’s former self when all the nuclear fuel in the star’s core has burned. Studying these white dwarfs gives astronomers an important view of the endpoint of most stars. Recently, researchers from the University of Texas have confirmed the existence of a new type of dwarf star, a “pulsating carbon white dwarf.” Since pulsating stars can reveal the inner workings of these stars, astronomers are hoping now to be able to learn more about what goes on inside white dwarf stars.

Until recently, astronomers knew of only two types of white dwarf stars: those that have an outer layer of hydrogen (about 80 percent), and about those with an outer layer of helium (about 20 percent), whose hydrogen shells have somehow been stripped away. Then in 2007, a third type was discovered, a very rare “hot carbon white dwarf.” These stars have had both their hydrogen and helium shells stripped off, leaving their carbon layer exposed.

After these new carbon white dwarfs were announced, Michael H. Montgomery from the University of Texas calculated that pulsations in these stars were possible. Similar to how geologists study seismic waves from earthquakes to understand what goes on in Earth’s interior astronomers can study the changes in light from a pulsating star to “look” into the star’s interior. In fact, this type of star-study is called “asteroseismology.”

Montgomery and his team began a systematic study of carbon white dwarfs with the Struve Telescope at McDonald Observatory, looking for pulsators. They discovered a pulsating star about 800 light-years away in the constellation Ursa Major, (called SDSS J142625.71+575218.3) fits the into this category. Its light intensity varies regularly by nearly two percent about every eight minutes.

“The discovery that one of these stars is pulsating is remarkably important,” said National Science Foundation astronomer Michael Briley. “This will allow us to probe the white dwarf’s interior, which in turn should help us solve the riddle of where the carbon white dwarfs come from and what happens to their hydrogen and helium.”

The star lies about ten degrees east northeast of Mizar, the middle star in the handle of the Big Dipper. This white dwarf has about the same mass as our Sun, but its diameter is smaller than Earth’s. The star has a temperature of 35,000 degrees Fahrenheit (19,500 C), and is only 1/600th as bright as the Sun.

Original News Source: McDonald Observatory Press Release

Posted on by Nancy Atkinson

Jupiter’s Rings Are ‘Made in the Shade’

Jupiter's rings. Image Credit: University of Maryland

Robotic spacecraft can gather a lot of data, and sometimes it takes years to sort through all the information acquired. Case in point: The Galileo spacecraft orbited Jupiter from 1995-2003. One discovery made by this mission was an anomaly in Jupiter’s rings. For the most part, the rings fall into the standard model of ring formation where the ring particles are shepherded by the orbits of four of Jupiter’s moons; Adrastea, Metis, Amalthea and Thebe (closest to farthest.) But a faint outward protrusion of dust extends beyond the orbit of Thebe, and scientists were mystified why this was occurring.

But a new study of data from the Galileo mission has found that this extension results from the interplay of shadow and sunlight on dust particles that make up the rings.

“It turns out that the outer ring’s extended boundary and other oddities in Jupiter’s rings really are ‘made in the shade,'” said Douglas Hamilton, a professor of astronomy at the University of Maryland. “As they orbit about the planet, dust grains in the rings alternately discharge and charge when they pass through the planet’s shadow. These systematic variations in dust particle electric charges interact with the planet’s powerful magnetic field. As a result small dust particles are pushed beyond the expected ring outer boundary, and very small grains even change their inclination, or orbital orientation, to the planet.”

The Galileo spacecraft was deliberately maneuvered to plunge into Jupiter in 2003 in an effort to protect one of its own discoveries – a possible ocean beneath the icy crust of the moon Europa (scientists didn’t want the spacecraft to one day impact and possibly contaminate Europa.) During this maneuver, the spacecraft dove through the rings and registered thousands of impacts from dust particles with its supersensitive dust detector.

Hamilton and German co-author Harald Krüger studied the impact data on dust grain sizes, speeds, and orbital orientations. Krüger analyzed the new data set and Hamilton created elaborate computer models that matched dust and imaging data on Jupiter’s rings and explained the observed unexpected behavior.

Take a look at Hamilton’s incredible models here.

“Within our model we can explain all essential structures of the dust ring we observed, ” said Krüger.

According to Hamilton, the mechanisms they identified affect the rings of any planet in any solar system, but the effects may not be as evident as it is at Jupiter. “The icy particles in Saturn’s famous rings are too large and heavy to be significantly shaped by this process, which is why similar anomalies are not seen there, ” he said. “Our findings on the effects of shadow may also shed some light on aspects of planetary formation because electrically charged dust particles must somehow combine into larger bodies from which planets and moons are ultimately formed.”

Original News Source: University of Maryland press release

Posted on by Nancy Atkinson

Spirit’s Dust Dilemma

Steve Squyres and the Mars Exploration Rover team knew from the beginning that dust could cause a problem for the rovers, Spirit and Opportunity. When a thick layer of dust coats the solar panels, it blocks the sunlight that generates power for the six-wheeled robots. In the summer of 2007 a huge dust storm blanketed Mars, and deposited a fair amount of dust on solar panels of both rovers. Spirit, especially accumulated a lot of dust on its solar array. Currently, only about one-third of incoming sunlight is able to penetrate dust on Spirit’s solar panels to be converted to electricity. As a result, Spirit is experiencing the lowest energy levels to date and accumulating a backlog of data waiting to be transmitted to Earth. If only a dust devil would come along!

Spirit’s solar array input has been approximately 240 watt-hours per Martian day, or sol (100 watt-hours is the amount of energy needed to light a 100-watt bulb for one hour). The skies in the area are now clear, which means additional dust shouldn’t be accumulating on the solar panels, and sunlight should be abundant. But clear skies also mean lower temperatures on the surface of Mars, increasing the bitter cold experienced by Spirit’s rover electronics module during the current Mars winter. Nighttime temperatures are creeping closer to the point where they will trigger the survival heaters, which draw a large amount of power.

The rover team has been using the strategy of keeping Spirit awake long enough each day to keep the electronics module sufficiently warm with heat from normal operations, providing more time for science observations. However, recently the team has done less science operations in order to allow Spirit’s batteries to recharge. The engineers are being creative in the trade-offs the team makes each day to keep Spirit going through the Martian winter. Another way they are conserving energy is by restricting the number of sols on which Spirit receives direct-from-Earth instructions via the rover’s high-gain antenna and transmits data to Earth via the Odyssey orbiter.

The MER team is hoping for a dust devil event to come and clear off the solar panels, like these dust devils did back in 2005.

This image shows the difference in the dust accumulation before and after the dust-cleaning event back in 2005.

And this is a self-portrait the rover took of its cleaned solar panels in 2005. Here’s hoping Spirit can be wiped clean again, and the sooner the better.

Original News Source: Mars Rover website

Posted on by Nancy Atkinson

Shape Shifting Robot Can Reassemble After Crashing Apart

It’s fairly certain that the Mars Polar Lander and the Beagle lander crash landed on Mars, never to be heard from again. Well, what if crash landing was no problem? What if a robotic spacecraft could just reassemble and fix itself if there was a mishap on the way to another planet’s surface? That type of science fiction is getting closer to reality. A group of researchers from the University of Pennsylvania have developed a robot made of separate modules that can recognize each other and reassemble itself if they crash or get kicked apart. Maybe this could solve the problems of landing on Mars!
 Except we haven’t figured out how to reassemble people, yet.

Take a look a the video. It’s pretty remarkable, although I have to admit, I had visions of the Terminator after watching it….

Original News Source: New Scientist

Posted on by Nancy Atkinson

Where In The Universe?

The past couple of weeks we’ve had a ‘mystery’ image, and asked our readers to guess what world in our solar system was featured in the image. Most everyone seemed to enjoy it, and it was fairly popular, so we’ve decided to make it a regular feature. I was going to call it the ‘Wednesday Where in the World (and What World) Is This?’ but that’s just too long, not to mention too many W’s in one headline. So to brief it up, and since this is “Universe Today,” we’ve decided to call it “Where In The Universe?” Look for it every Wednesday.

Above is this week’s mystery image. If you keep an eye on the images being released by the various spacecraft traveling our solar system, you may have seen this one before. Remember, you have 8 planets, 169 known moons, a handful of dwarf planets and lots of asteroids in our solar system to choose from. Don’t cheat — make your guess before you click to continue…

This is an image of Saturn’s moon Titan, taken by the Huygen’s probe as it descended through Titan’s thick atmosphere and down to the surface. It’s a Mercator projection, or a flattened image of the curved globe of Titan. Don’t feel bad if you guessed Mars — the coloring and mountains are reminiscent of Mars, or even some areas on Earth. It’s exciting to know that Titan has those similar features, too.


This is a full poster of images taken at four different altitudes from the descent imager/spectral radiometer on the European Space Agency’s Huygens probe, showing aerial views of the landing site. The images were taken on Jan. 14, 2005. Coming up in less than 12 days, Cassini will flyby Titan at a fairly close proximity, at about 1000 km (621 miles) above the surface of this interesting moon. The flyby will be on May 12, 2008.

Original Source: Cassini website

Posted on by Nancy Atkinson

Cassini Watches Five-Month-Long Lightning Storm Rage on Saturn

Cassini scientists know for sure their spacecraft isn’t in Kansas anymore. Cassini’s been keeping an eye on a powerful electrical storm that’s been raging on Saturn for five months now, with lightning bolts 10,000 times more powerful than those found on Earth. But Cassini has also been busy flying by moons like Enceladus and Titan during this time, and therefore can’t constantly watch the storm. So amateur astronomers have been assisting the Cassini science team by monitoring this tempest in the “Storm Alley” region of Saturn. It’s no Great Red Spot, but it’s the longest lasting electrical storm ever detected in our solar system.

This prolonged storm is located in Saturn’s southern hemisphere–in a region nicknamed “Storm Alley” by mission scientists–where previous, but much shorter-lived lightning storms (if month-long storms can be called short!) were observed by Cassini. Saturn’s electrical storms are similar to thunderstorms on Earth, but they’re much bigger and longer lasting. Storms on Saturn have diameters of several thousand kilometers (thousands of miles), and radio signals produced by their lightning are thousands of times more powerful than those produced by terrestrial thunderstorms.

The storm was first detected on Saturn on Nov. 27, 2007. The electrostatic discharges were picked up by Cassini’s radio and plasma wave science instrument.

“The electrostatic radio outbursts have waxed and waned in intensity for five months now,” said Georg Fischer, an associate with the radio and plasma wave science team at the University of Iowa, Iowa City. “We saw similar storms in 2004 and 2006 that each lasted for nearly a month, but this storm is longer-lived by far. And it appeared after nearly two years during which we did not detect any electrical storm activity from Saturn.”

Amateur astronomers have kept track of the storm over its five-month lifetime. “Since Cassini’s camera cannot track the storm every day, the amateur data are invaluable,” said Fischer. “I am in continuous contact with astronomers from around the world.”

The long-lived storm will help provide information on the processes powering Saturn’s intense lightning activity. Cassini scientists will continue to monitor Storm Alley as the seasons change, bringing the onset of autumn to the planet’s southern hemisphere.

Original News Source: Cassini Press Release

Posted on by Nancy Atkinson

Hubble Surprise: Heavyweight Baby Galaxies

Astronomers looking at galaxies in the universe’s distant past were surprised to find some compact, very young galaxies that have masses similar to a mature, grown-up galaxy. Using the Hubble Space Telescope, astronomers discovered nine small galaxies, each weighing in at 200 billion times the mass of the Sun. The galaxies, each only 5,000 light-years across, are a fraction of the size of today’s adult galaxies but contain approximately the same number of stars. Each galaxy could fit inside the central hub of our Milky Way Galaxy.

Using the Hubble in conjunction with Keck Observatory in Hawaii, astronomers were able to study the galaxies as they existed 11 billion years ago, when the Universe was less than 3 billion years old.

“Seeing the compact sizes of these galaxies is a puzzle”, said Pieter G. van Dokkum of Yale University in New Haven, Connecticut, USA, who led the study. “No massive galaxy at this distance has ever been observed to be so compact. These galaxies would have to change a lot over 11 billion years, growing five times bigger. They could get larger by colliding with other galaxies, but such collisions may not be the complete answer. It is not yet clear how they would build themselves up to become the large galaxies we see today.”

To determine the sizes of the galaxies, the team used the Near Infrared Camera and Multi-Object Spectrometer on Hubble. For the Keck observations, a powerful laser was used to correct for image blurring caused by the Earth’s atmosphere. Only Hubble, Keck and ESO’s Very Large Telescope are really able to measure the sizes of these galaxies as they are very small and far away.

The ultra-dense galaxies might comprise half of all galaxies of that mass 11 billion years ago, van Dokkum said, forming the building blocks of today’s largest galaxies.

How did these small, crowded galaxies form? One way, suggested van Dokkum, involves the interaction of dark matter and hydrogen gas in the nascent Universe. Dark matter is an invisible form of matter that accounts for most of the Universe’s mass. Shortly after the Big Bang, the Universe contained an uneven landscape of dark matter. Hydrogen gas became trapped in pockets of the invisible material and began spinning rapidly in dark matter’s gravitational whirlpool, forming stars at a furious rate.

Based on the galaxies’ mass, which is derived from their color, the astronomers estimated that the stars are spinning around their galactic disks at roughly 400 to 500 kilometers per second. Stars in today’s galaxies, by contrast, are traveling at about half that speed because they are larger and rotate more slowly than the compact galaxies.

The astronomers say that these galaxies are ideal targets for the Wide Field Camera 3, which is scheduled to be installed aboard Hubble during upcoming Servicing Mission 4 in the fall of 2008.

Original News Source: European Hubble Space Telescope Homepage

Posted on by Nancy Atkinson

Looking For a Free Ride To Venus?

The folks over at Ars Technica report that the Japanese Space Agency, JAXA, announced they are now accepting proposals for a microprobe that can hitch a ride with the Venus Climate Orbiter, Japan’s upcoming robotic mission to Venus. They will provide a free ride to either a low-Earth orbit or on a trajectory toward Venus. There are just a few requirements that JAXA has specified:

The launch booster for the Venus Climate Orbiter has room for one piggyback probe that can weigh up to 40 kilograms. It must fit into a 50x50x50 centimeter cube. After the microprobe is released, it will be on its own. JAXA will not assist with further correcting its trajectory or inserting it into an orbit around Venus.

The proposal must be submitted by a researcher based at a Japanese institution, and the mission will have to be managed in Japan. However, this does not preclude a Japanese team from collaborating with foreign researchers on a proposal. Also, all the documents for information and proposals are written in Japanese.

But if you’re in the market for a ride to Venus, the deadline for submitting your proposal is May 23, 2008. The announcement of JAXA’s micro-satellite program is posted here, and the specific announcement for piggybacking on Venus Climate Orbiter is here. The requirements for the micro-satellite and the application forms are found here.

Piggybacked micro-mission to a planet has been done before: NASA’s failed Mars Polar Lander mission had two accompanying microprobes, each weighing only 2.4 kilograms, that would have penetrated the Martian soil to take measurements if the mission had gone better. Mars Polar Lander and the two penetrator probes—named Deep Space 2—all failed independently of one another.

Original News Source: Ars Technica

Posted on by Nancy Atkinson

10 Satellites Launched in Record Setting Mission for India (Video)

India’s space agency sent a record 10 satellites into Earth orbit with a single launch early Monday. The Polar Satellite Launch Vehicle (PSLV) rocket ejected all the satellites within minutes of each other after liftoff from the Sriharikota space station in southern India. Initial signals indicated all the satellites were working normally. India is seeking to compete with other space-faring nations for commercial launch services, and this mission’s success demonstrates India’s ability to launch multiple payloads into precise orbit. The flight breaks the previous record of eight satellites launched at once by a Russian rocket, according to Indian news reports.


It was the 13th flight of the Polar Satellite Launch Vehicle, which has “repeatedly proved itself as a reliable and versatile workhorse launch vehicle,” said Indian Space Research Organization (ISRO.) Later this year India will launch its own a lunar mission, Chandrayaan which will orbit the moon to create chemical and topographical maps.

The satellites included a 690-kilogram (1,518-pound) remote-sensing satellite, Cartosat-2A, an 83-kilogram mini-satellite and a cluster of eight so-called nano-satellites, each weighing between three kilograms and 16 kilograms. The two larger satellites were built by the ISRO, but the nano-satellites were built by research institutions from Europe, Canada and Japan.

“[India] wants to market its launch systems and also its capability in earth imagery,” said Ajay Lele, a space expert at the Institute of Defence Studies and Analyses in New Delhi. “The mission is very significant from a commercial point of view.”

“The mission was perfect,” said ISRO chairman G. Madhavan after the launch was telecast live.

“It is a historic moment for us because it is the first time that we have launched 10 satellites in a single mission,” he added.

Cartosat-2A, the main satellite launched Monday to an altitude of 630 kilometres (391 miles) above earth, also has a domestic economic dimension and can be used for intelligence gathering as well, officials say.

Here’s a YouTube Video from an Indian television station (in English) with more information about the launch.

Last year, India launched an Italian spacecraft into orbit, and in January 2008, it launched an Israeli spy satellite.

For more information about India’s space agency: ISRO.

Original News Source: AFP