Universe Today

September 15, 2009December 24, 2015 by Fraser Cain

International Space Station Pictures

International Space Station. Credit: NASA

With most of the construction of the International Space Station now complete, it’s quite an impressive sight to see. In fact, the space station is the brightest manmade object in space. It’s easy to see if you just know when and where to look. Check out our ISS tracking page with links to resources to find the station.

Here are some cool International Space Station pictures.

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This is a classic artist’s rendering of what the International Space Station will look like when all of its modules have been attached.

The International Space Station. Credit: NASA

And here’s another cool picture of the International Space Station.

Space station above the Earth. Image credit: NASA

Here’s a cool image of the International Space Station captured by the space shuttle. It shows the station in orbit above the Earth.

Our Earth's horizon and the International Space Station's solar array panels are featured in this image photographed by the Expedition 17 crew in August 2008. Credit: NASA

You don’t get to see the full station in this picture, but it’s a beautiful view of the Earth’s horizon off to the side.

Another great image of the International Space Station.

We have written many many articles about the International Space Station for Universe Today. Here’s an article about how the station is so bright now it’s visible during the daytime. Here’s a link to NASA’s gallery of space station images.

September 15, 2009April 26, 2016 by Nancy Atkinson

New Evidence of Dry Lake Beds on Mars

Desiccation patterns on Earth (left) and Mars (right). Credit: Google/NASA/JPL

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Networks of giant polygonal troughs found in crater basins on Mars are cracks caused by evaporating lakes. These landforms had been attributed to thermal contractions in the Martian permafrost, similar to what the Phoenix lander explored near the north pole on the Red Planet. But these polygon-shaped cracks are too large to be caused by thermal contractions and provide further evidence of a warmer, wetter Martian past.

Speaking at the European Planetary Science Conference, M. Ramy El Maarry of the Max Planck Institute for Solar System Research said was excited when he saw that the crater floor polygons seemed to be too large to be caused by thermal processes. “I also saw that they resembled the desiccation cracks that we see on Earth in dried up lakes,” he said. “These are the same type of patterns you see when mud dries out in your back yard, but the stresses that build up when liquids evaporate can cause deep cracks and polygons on the scale I was seeing in the craters.”

Detailed image of large-scale crater floor polygons, caused by desiccation process, with smaller polygons caused by thermal contraction inside. The central polygon is 160 metres in diameter, smaller ones range 10 to 15 metres in width and the cracks are 5-10 metres across. Credit: NASA/JPL

The polygons are formed when long cracks in the surface of the Martian soil intersect. El Marry investigated networks of cracks inside 266 impact basins across the surface of Mars and observed polygons reaching up to 250 metres in diameter. Polygonal troughs have been imaged by several recent missions and until now, were thought to have been created by the same conditions as at the polar regions.

El Maarry created an analytical model to determine the depth and spacing of cracks caused by stresses building up through cooling in the Martian soil. He found that polygons caused by thermal contraction could have a maximum diameter of only about 65 meters, much smaller than the troughs he was seeing in the craters.

El Maarry identified the crater floor polygons using images taken by the MOC camera on Mars Global Surveyor and the HiRISE and Context cameras on Mars Reconnaissance Orbiter. The polygons in El Maarry’s survey had an average diameter of between 70 and 140 meters, with the width of the actual cracks ranging between 1 and 10 meters.

Evidence suggests that between 4.6 and 3.8 billion years ago, Mars was covered in significant amounts of water. Rain and river water would have collected inside impact crater basins, creating lakes that may have existed for several thousand years before drying out. However, El Maarry believes that, in the northern hemisphere, some of the crater floor polygons could have been formed much more recently.

“When a meteorite impacts with the martian surface, the heat can melt ice trapped beneath the martian crust and create what we call a hydrothermal system. Liquid water can fill the crater to form a lake, covered in a thick layer of ice. Even under current climatic conditions, this may take many thousands of years to disappear, finally resulting in the desiccation patterns,” said El Maarry.

Source: Europlanet

September 15, 2009December 24, 2015 by Nancy Atkinson

Titan’s Haze Acts as Ozone Layer

Crucial building blocks in the organic haze layers of Titan and possibly of early Earth come from chemical reactions. Image credits courtesy of NASA-JPL, Dr. Xibin Gu, and Reaction Dynamics Group, University of Hawaii.

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Titan appears to be more like Earth all the time, and a new understanding of Titan’s hazy atmosphere could provide clues to the evolution of Earth’s early atmospheric environment and the development of life on our home planet. Researchers have discovered a series of chemical reactions on Saturn’s largest moon that may shield the moon’s surface from ultraviolet radiation, similar to how Earth’s ozone layer works. The reactions may also be responsible for forming the large organic molecules that compose the moon’s thick and hazy orange atmosphere.

Scientists have long understood that high in Titan’s atmosphere, sunlight breaks apart methane into carbon and hydrogen. These elements react with nitrogen and other ingredients to form a thick haze of complex hydrocarbons which completely enshrouds the moon.

But recently, the role of polyynes in the chemical evolution of Titan’s atmosphere has been vigorously researched and debated. Polyynes are a group of organic compounds with alternating single and triple bonds, such as diacetylene (HCCCCH) and triacetylene (HCCCCCCH). These polyynes are thought to serve as an UV radiation shield in planetary environments, and could act as prebiotic ozone. This would be important for any life attempting to form on Titan.

“Even if you form biologically important molecules (via other reactions) and there is no ozone or ozone like-layer, these molecules will not always survive the harsh radiation environment,” said Ralf Kaiser, lead scientist of the study.

However, the underlying chemical processes that initiate the formation and control the growth of polyynes have not been understood.

Kaiser and his colleagues studied the formation of triacetylene and larger organic molecules in the lab and in computer simulations. They found that triacetylene can be formed by collisions between two small molecules in a reaction that can be easily initiated under the cold conditions found in Titan’s atmosphere.

The authors suggest that triacetylene, an organic molecule that could act as a shield for ultraviolet radiation, may serve as the building block for creating complex molecules in Titan’s atmosphere.

“The present experiments are conducted with molecules containing carbon and hydrogen atoms only,” Kaiser told Universe Today. “To investigate the formation of astrobiologically important molecules on Titan, we have to ‘add’ oxygen and nitrogen, too.” Kaiser said they plan to do those type of experiments later this year.

The team said they hope their combined experimental,theoretical, and modeling study will act as a template, and trigger much needed, successive investigation of the chemistry of surrounding Titan so that a more complete picture of the processes involved in the chemical processing of moon’s atmosphere will emerge.

Lead image caption: Crucial building blocks in the organic haze layers of Titan and possibly of early Earth come from chemical reactions. Image credits courtesy of NASA-JPL, Dr. Xibin Gu, and Reaction Dynamics Group, University of Hawaii

Source: PNAS

September 14, 2009December 24, 2015 by Nancy Atkinson

Super Cell Lightning Storm Raging on Saturn Since January

Saturn lightning storm. Credit: RPWS Team/NASA/JPL/Space Science Institute

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The Cassini spacecraft has been in orbit around Saturn since 2004 and during its mission, has watched nine different lightning storms rage on the planet. But this latest one is the longest lasting and most powerful storm yet: it has been going on since mid-January 2009 with no end in sight. It broke the storm duration record of 7.5 months set by another thunderstorm observed by Cassin between November 2007 and July 2008. Lightning discharges in Saturn’s atmosphere emit very powerful radio waves which are about 10,000 times stronger than their terrestrial counterparts and the huge thunderstorms in Saturn’s atmosphere have diameters of about 3,000 km.

The storm is coursing through “Storm Alley,” a region which lies 35 degrees south of Saturn’s equator where these mammoth storms occur. On board Cassini measuring these storms are the antennas and receivers of the Cassini Radio and Plasma Wave Science (RPWS) instrument.

“These lightning storms are not only astonishing for their power and longevity,” Dr. Georg Fischer of the Austrian Academy of Sciences, “the radio waves that they emit are also useful for studying Saturn’s ionosphere, the charged layer that surrounds the planet a few thousand kilometers above the cloud tops. The radio waves have to cross the ionosphere to get to Cassini and thereby act as a natural tool to probe the structure of the layer and the levels of ionization in different regions.”

Image of a lightning storm on Saturn: Credit: NASA/JPL/Space Science Institute

The observations of Saturn lightning using the Cassini RPWS instrument are being carried out by an international team of scientists from Austria, the US and France. Results have confirmed previous studies of the Voyager spacecraft indicating that levels of ionization are approximately 100 times higher on the day-side than the night side of Saturn’s ionosphere.

“The reason why we see lightning in this peculiar location is not completely clear,” said Fischer. “It could be that this latitude is one of the few places in Saturn’s atmosphere that allow large-scale vertical convection of water clouds, which is necessary for thunderstorms to develop. However, it may be a seasonal effect. Voyager observed lightning storms near the equator, so now that Saturn has passed its equinox on 11 August, we may see the storms move back to equatorial latitudes.”

Saturn’s role as the source of lightning was given added confirmation during Cassini’s last close flyby of Titan on August 25. During the half hour that Cassini’s view of Saturn was obscured by Titan, no lightning was observed. “Although we know from Cassini images where Saturn lightning comes from, this unique event was another nice proof for their origin.” said Fischer.

Fischer presented his findings at the European Planetary Science Congress in Potsdam, Germany.

Source: Europlanet

September 14, 2009December 24, 2015 by Jean Tate

Hubble’s Law

velocity vs distance, from Hubble's 1929 paper

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“The distance to objects beyond the Local Group is closely related to how fast they seem to be receding from us,” that’s Hubble’s law in a nutshell.

Edwin Hubble, the astronomer the Hubble Space Telescope is named after, first described the relationship which later bore his name in a paper in 1929; here is one of the ways he described it, in that paper: “The data in the table [of “nebulae”, i.e. galaxies] indicate a linear correlation between distances and velocities“; in numerical form, v = Hd (v is the speed at which a distant object is receding from us, d is its distance, and H is the Hubble constant).

Today the Hubble law is usually expressed as a relationship between redshift and distance, partly because redshift is what astronomers can measure directly.

Hubble’s Law, which is an empirical relationship, was the first concrete evidence that Einstein’s theory of General Relativity applied to the universe as a whole, as proposed only two years earlier by Georges Lemaître (interestingly, Lemaître’s paper also includes an estimate of the Hubble constant!); the universal applicability of General Relativity is the heart of the Big Bang theory, and the way we see the predicted expansion of space is as the speed at which things seem to be receding being proportional to their distance, i.e. Hubble’s Law.

Although other astronomers, such as Vesto Silpher, did much of the work needed to measure the galaxy redshifts, Hubble was the one who developed techniques for estimating the distance to the galaxies, and who pulled it all together to show how distance and speed were related.

Hubble’s Law is not exact; the measured redshift of some galaxies is different from what Hubble’s Law says it should be, given their distances. This is particularly noticeable for galaxy clusters, and is explained as the motion of galaxies within their local groups or clusters, due to their mutual gravitation.

Because the exact value of the Hubble constant, H, is so important in extragalactic astronomy and cosmology – it leads to an estimate of the age of the universe, helps test theories of Dark Matter and Dark Energy, and much more – a great deal of effort has gone into working it out. Today it is estimated to be 71 kilometers per second per megaparsec, plus or minus 7; this is about 21 km/sec per million light-years. What does this mean? An object a million light-years away would be receding from us at 21 km/sec; an object 10 million light-years away, 210 km/sec, etc.

Perhaps the most dramatic revision to the Hubble Law came in 1998, when two teams independently announced that they’d discovered that the rate of expansion of the universe is accelerating; the shorthand name for this observation is Dark Energy.

Harvard University’s Professor of Cosmology John Huchra maintains a webpage on the history of the Hubble constant, and this page from Ned Wright’s Cosmology Tutorial explains how the Hubble law and cosmology are related.

There are several Universe Today stories about the Hubble relationship and the Hubble constant; for example Astronomers Closing in on Dark Energy with Refined Hubble Constant, and Cosmologists Improve on Standard Candles Measurement.

And we have done some Astronomy Casts on it too, How Old is the Universe? and, How Big is the Universe?

Sources:
UT-Knoxville
NASA
Cornell Astronomy

September 14, 2009December 29, 2015 by Nancy Atkinson

Carnival of Space #120

This week’s Carnival of Space is hosted by Bruce Irving over at Music of the Spheres

Click here to read the Carnival of Space #120.

And if you’re interested in looking back, here’s an archive to all the past Carnivals of Space. If you’ve got a space-related blog, you should really join the carnival. Just email an entry to [email protected], and the next host will link to it. It will help get awareness out there about your writing, help you meet others in the space community – and community is what blogging is all about. And if you really want to help out, let Fraser know if you can be a host, and he’ll schedule you into the calendar.

Finally, if you run a space-related blog, please post a link to the Carnival of Space. Help us get the word out.

September 14, 2009September 14, 2009 by Nancy Atkinson

Armadillo Powers Toward $1 Million Prize

A rocket powered vehicle successfully completed the first step toward qualifying to win a $1 million prize for NASA’s Northrop Grumman Lunar Lander Challenge. Armadillo Aerospace’s “Scorpius” lander set world records for vertical landings and takeoff flights by flying up 50 meters (164 feet) into the air, maneuvering over to land on a simulated rocky lunar surface 50 meters (164 feet) away, and then rising and flying back to land where it started. The flight included a requirement of at least 180 seconds of flying time. Watch the video from the second qualifying flight here. Armadillo is the first team of three teams looking to nab the prize this year.
Continue reading “Armadillo Powers Toward $1 Million Prize”

September 14, 2009December 24, 2015 by Nancy Atkinson

Interactive 360-Degree Panorama of Entire Night Sky Now Available

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A stunning new 800-million-pixel panorama of the entire sky has been released online for everyone to enjoy. GigaGalaxy Zoom is a project for the International Year of Astronomy, and it allows users to dive right into the Milky Way Galaxy, and learn more about our celestial neighborhood. The project allows stargazers to explore and experience the Universe as it is seen with the unaided eye from ESO’s observing sites in Chile, one of the darkest and best viewing locations in the world.

With this tool users can learn more about many different and exciting objects in the image, such as multicolored nebulae and exploding stars, just by clicking on them. In this way, the project seeks to link the sky we can all see with the deep, “hidden” cosmos that astronomers study on a daily basis.

This is the first of three extremely high-resolution images that will be featured in the GigaGalaxy Zoom project. Another image will be released next week, on Sept. 21.

Click here for a preview video.

The production of this image came about as a collaboration between ESO, the renowned French writer and astrophotographer Serge Brunier and his fellow Frenchman Frédéric Tapissier. Brunier spent several weeks during the period between August 2008 and February 2009 capturing the sky, mostly from ESO observatories at La Silla and Paranal in Chile.

The resulting image, now available on GigaGalaxy Zoom, is composed of almost 300 fields each individually captured by Brunier four times, adding up to nearly 1200 photos that encompass the entire night sky.

“I wanted to show a sky that everyone can relate to — with its constellations, its thousands of stars, with names familiar since childhood, its myths shared by all civilisations since Homo became Sapiens,” says Brunier. “The image was therefore made as man sees it, with a regular digital camera under the dark skies in the Atacama Desert and on La Palma.”

Giga Galaxy Zoom site.

Serge Brunier’s website

Source: ESO

September 13, 2009December 24, 2015 by Nancy Atkinson

Jupiter Captured Comet as Temporary Moon

Jupiter from the newly refurbished Hubble. Credit: NASA, ESA, M. Wong (Space Telescope Science Institute, Baltimore, Md.), H. B. Hammel (Space Science Institute, Boulder, Colo.), and the Jupiter Impact Team

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Jupiter’s gravity well has been known to capture objects – evidenced by the recent impact on the gas giant discovered by amateur astronomer Anthony Wesley. But one object captured by Jupiter in the mid 1900’s was later able to escape from the planet’s clutches. Researchers have found comet 147P/Kushida-Muramatsu was captured as a temporary moon of Jupiter, and remained trapped in an irregular orbit for about twelve years. “Our results demonstrate some of the routes taken by cometary bodies through interplanetary space that can allow them either to enter or to escape situations where they are in orbit around the planet Jupiter,” said team member Dr. David Archer.

With this discovery, five such objects have now been discovered where the phenomenon of temporary satellite capture (TSC) has occurred, but this new research suggests it might happen more frequently than was expected. Kushida-Muramatsu orbited Jupiter between 1949 and 1961, the third longest capture period of the five objects.

An international team led by Dr. Katsuhito Ohtsuka modeled the trajectories of 18 “quasi-Hilda comets,” objects with the potential to go through a temporary satellite capture by Jupiter that results in them either leaving or joining the “Hilda” group of objects in the asteroid belt. Most of the cases of temporary capture were flybys, where the comets did not complete a full orbit. However, the research team used recent observations tracking Kushida-Muramatsu over nine years to calculate hundreds of possible orbital paths for the comet over the previous century. In all scenarios, Kushida-Muramatsu completed two full revolutions of Jupiter.

Figure showing comet Kushida-Muramatsu’s orbital path around Jupiter (credit: Ohtsuka/Asher):

“Asteroids and comets can sometimes be distorted or fragmented by tidal effects induced by the gravitational field of a capturing planet, or may even impact with the planet,” said Archer, as did comet D/1993 F2 (Shoemaker-Levy 9), which was torn apart on passing close to Jupiter and whose fragments then collided with that planet in 1994. Previous computational studies have shown that Shoemaker-Levy 9 may well have been a quasi-Hilda comet before its capture by Jupiter. The object that impacted with Jupiter this July, causing a new dark spot may also have been a member of this class, even if it did not suffer tidal disruption like Shoemaker-Levy.

“Our work has become very topical again with the discovery this July of an expanding debris plume, created by the dust from the colliding object, which is the evident signature of an impact. The results of our study suggest that impacts on Jupiter and temporary satellite capture events may happen more frequently than we previously expected,” said Asher.

The team has also confirmed a future moon of Jupiter. Comet 111P/Helin-Roman-Crockett, which has already orbited Jupiter three times between 1967 and 1985, is due to complete six laps of the giant planet between 2068 and 2086.

“Fortunately for us Jupiter, as the most massive planet with the greatest gravity, sucks objects towards it more readily than other planets and we expect to observe large impacts there more often than on Earth. Comet Kushida-Muramatsu has escaped from the giant planet and will avoid the fate of Shoemaker-Levy 9 for the foreseeable future,” said Asher.

The discovery was be presented at the European Planetary Science Congress in Potsdam.

Source: Europlanet

September 13, 2009December 24, 2015 by Nancy Atkinson

Temporary Radiation Belt Discovered at Saturn

Radiation belt map of the ions with energies between 25-60 MeV, in Saturn's magnetosphere, based on several years of Cassini MIMI/LEMMS data. The structure of this radiation belt is almost perfectly stable for more than 5 years of Cassini observations, despite the intense variability of the radiation belts, outside the location of Tethys.

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A new, temporary radiation belt has been detected at Saturn, located about 377,000 km from the center of the planet, near the orbit of the moon Dione. The temporary radiation belt was short-lived and formed three times in 2005. It was observed as sudden increases in the intensity of high energy charged particles in the inner part of Saturn’s magnetosphere, in the vicinity of the moons Dione and Tethys, and likely was caused by a change in the intensities of cosmic rays at Saturn.

“These intensifications, which could create temporary satellite atmospheres around these moons,” said Dr. Elias Roussos, “occurred three times in 2005 as a response to an equal number of solar storms that hit Saturn’s magnetosphere and formed a new, temporary component to Saturn’s radiation belts.”

The discovery was made possible by Cassini’s five-plus year mission, allowing scientists to observe and assess changes in Saturn’s radiation belts. An international team of astronomers made the discovery analyzing data from the Magnetospheric Imaging instrument (MIMI) on Cassini MIMI’s LEMMS sensor, which measures the energy and angular distribution of charged particles in the magnetic bubble that surrounds Saturn.

The new belt, which has been named “the Dione belt”, was only detected by MIMI/LEMMS for a few weeks after each of its three appearances. The team believe that newly formed charged particles in the Dione belt were gradually absorbed by Dione itself and another nearby moon, named Tethys, which lies slightly closer to Saturn at an orbit of 295 000km.

Unlike the Van Allen belts around the Earth, Saturn’s radiation belts inside the orbit of Tethys are very stable, showing negligible response to solar storm occurrences and no variability over the five years that they have been monitored by Cassini.

Interestingly, it was found that the transient Dione belt was only detected outside the orbit of Tethys. It appeared to be clearly separated from the inner belts by a permanent radiation gap all along the orbit of Tethys.

“Our observations suggest that Tethys acts as a barrier against inward transport of energetic particles and is shielding the planet’s inner radiation belts from solar wind influences. That makes the inner, ionic radiation belts of Saturn the most isolated magnetospheric structure in our solar system“, said Dr Roussos.

The radiation belts within Tethys’s orbit probably arise from the interaction of the planet’s main rings and atmosphere and galactic cosmic ray particles that, unlike the solar wind, have the very high energies needed to penetrate the innermost Saturnian magnetosphere. This means that the inner radiation belts will only vary if the cosmic ray intensities at the distance of Saturn change significantly.

However, Roussos emphasized that outside the orbit of Tethys, the variability of Saturn’s radiation belt might be enhanced in the coming years as solar maximum approaches. “If solar storms occur frequently in the new solar cycle, the Dione belt might become a permanent, although highly variable, component of Saturn’s magnetosphere, which could affect significantly Saturn’s global magnetospheric dynamics,” he said.

The new findings were presented at the European Planetary Science Congress in Potsdam, Germany.