Universe Today

October 12, 2007December 26, 2015 by Fraser Cain

Has Dark Energy Always Been Constant?

Dark energy is that mysterious force that seems to be accelerating the expansion of the Universe. But the question is: has it always been pushing the Universe apart with the same force, or was it weaker or stronger in the past, and will it get stronger in the future? Researchers from the Harvard-Smithsonian Center for Astrophysics have a plan to study distant clumps of hydrogen, to get to the bottom of this question, once and for all.

Dark energy was first discovered nearly a decade ago, when astronomers noticed that distant supernovae were further away than their calculations were expecting. Some mysterious force appears to be accelerating the expansion of the Universe from every point in space. As space expands, more dark energy seems to appear. And although the amount of dark energy in any one point in space is tiny, across the vast reaches of space, it really adds up, accounting for more than 70% of the Universe.

If dark energy is increasing, however, you could imagine it eventually becoming so strong that it starts to tear galaxy clusters apart, and then galaxies themselves, and even star systems. Maybe it might even become so strong that it tears apart atoms and even the fabric of space itself. Astronomers call this theory the “Big Rip”. Or maybe just the opposite is true, and dark energy will eventually become negligible to the expansion of the Universe.

In order to see if the strength of dark energy is changing over time, astronomers are planning to carefully plot the position of clouds of neutral hydrogen, shortly after they formed from the Big Bang. Although it’s not possible now, future planned observatories should be able to trace this material all the way back to a time when the Universe was only 200 million years old.

In the early Universe, small fluctuations in energy density and pressure caused oscillations. Although tiny in the beginning, these ripples have been magnified by the expansion of the Universe so that they stretch 500 million light-years across today. The clouds of neutral hydrogen should follow the same ripple pattern, so astronomers will know they’re looking at those first, primordial clouds, and not some closer ones.

And so, astronomers will be able to look back in time, and study the distance to the clouds at each epoch in our Universe’s expansion. They should be able to trace how much dark energy was affecting space at each time, and get a sense if this energy has always remained constant, or if it’s changing.

Their answers will shape our understanding of the Universe’s evolution, and its future.

Original Source: CfA News Release

October 12, 2007December 26, 2015 by Fraser Cain

Titan has Drizzling Methane Rain

If you’re planning a visit to Saturn’s moon Titan, make sure you bring an umbrella. You’ll need it. Not to protect you from water raining down; on frigid Titan, where temperatures dip below 180-degrees Celsius, all the water is completely frozen. No, according to scientists, there’s a steady drizzle of liquid methane coming down in the mornings.

New infrared images gathered by Hawaii’s W.M. Keck Observatory and Chile’s Very Large Telescope show that Titan’s Xanadu region experiences a steady drizzle of methane during its lengthy morning. The concept of morning is a little misleading, since Titan takes about 16 Earth days to complete one rotation. So, the “morning” drizzle actually lasts around 3 Earth days, dissipating around 10:30 a.m. local time.

Astronomers aren’t actually sure if this is a moon-wide phenomenon, or just localized around the Xanadu region of Titan. Even though large lakes and seas have been discovered around the moon’s poles, no process had been discovered that fills them with liquid… until now.

Reporting their findings in the latest issue of the online journal Science Express, researchers from UC Berkeley note that, “widespread and persistent drizzle may be the dominant mechanism for returning methane to the surface from the atmosphere and closing the methane cycle.”

The new Keck/VLT images show a widespread cloud cover of frozen methane at a height of 25 to 35 kilometres. And then there are liquid methane clouds below 20 kilometres, and finally rain falling at the lowest elevations.

The droplets of liquid methane in the rain clouds are 1,000 times larger than water vapour here on Earth, and this surprisingly makes them harder to detect. Since the droplets are larger, but still carry the same amount of moisture, they’re much more spread out, making the clouds extremely diffuse, and nearly invisible.

How much liquid is trapped in the clouds? If you squeezed them all out and spread the liquid across the surface of Titan, it would coat the entire moon to a depth of about 1.5 cm. And that’s actually the same amount as we’d get if you did the same thing with the Earth’s clouds.

Original Source: UC Berkeley News Release

October 11, 2007December 26, 2015 by Fraser Cain

The Best Alien Hunter is Open for Business

The biggest and best tool ever developed to search for signs of extraterrestrial life is coming online in Northern California. No, it’s not an interstellar bounty hunter, it’s an array of radio dishes in Northern California. The Allen Array, located in an arid valley near the town of Hat Creek started gathering data with 42 radio dishes today. But that’s just the beginning; eventually there’ll be 350 dishes pointed to the heavens, listening for the faint communications from an extraterrestrial intelligence.

Partly funded by Microsoft co-founder Paul Allen, the Allen Telescope Array released its first test images today. These included a radio map of the nearby Andromeda Galaxy (M31) and the Pinwheel Galaxy (M33).

Although the array was used to capture radio images of galaxies, one of its primary roles will be to search for communications from extraterrestrial civilizations. It works on the idea that many smaller radio telescopes working together are more powerful and cheaper than a single large dish.

Over the next couple of decades, the Allen Array will gather 1,000 times as much radio data from distant stars as has already been accumulated in the 45 years of the SETI program. Astronomer Seth Shostak from the SETI Institute made a bold prediction, “I think we will find signals from intelligent civilizations by 2025.”

The total cost of the project to date is $50 million. The first phase of $25 million was funded by the Paul G Allen Family Foundation. Another group of donors contributed the additional $25 million. UC Berkeley and the SETI Institute are now working to raise the funding to complete the full 350-dish array.

The final 6-metre (20-foot) dish should be completed in approximately 3 years, bringing the full array online. The aliens won’t be able to hide from us much longer.

Original Source: UC Berkeley News Release

What is the biggest telescope in the world?

October 11, 2007December 26, 2015 by Fraser Cain

Lakes in Titan’s Northern Polar Region

NASA’s Cassini spacecraft has now mapped out 60 percent of Titan’s north pole region, and it’s looking downright aquatic. At least 14% of the region revealed by Cassini is covered in what look like liquid hydrocarbon lakes. Take a look at the photo associated with this story, see the dark black regions? Those are lakes. But not lakes like we see them here on Earth.

The new images were mapped out by Cassini’s radar instruments, which can detect the smoothness of the surface of Titan. Extremely smooth sections are thought to be a liquid, while the bumpier regions are solid ground. The largest sea discovered so far has a surface area of 100,000 square kilometres (40,000 square miles), bigger than Lake Superior here on Earth.

Planetary scientists think the seas are filled with liquid ethane, methane and dissolved nitrogen. So far, more than 400 separate bodies of liquid have been discovered.

Original Source: NASA/JPL/SSI News Release

October 11, 2007January 24, 2021 by Fraser Cain

Astrosphere for October 11, 2007

Here’s your space photo for the day. It’s an image of galaxy NGC 253, captured by Strongmanmike. This is just one of a series of new images released by Mike.

I briefly mentioned that one of the latest batch of astronauts headed to the International Space Station is Malaysia’s Sheikh Muszaphar Shukor. As a Muslim, he’s got the puzzling problem of praying in space.

The SpaceShipTwo is going to cause delays to Virgin Galactic’s plans for space tourism. Personal Spaceflight tries to figure out how much of a delay.

Now this is going to be good. An upcoming episode of Nova will cover the recent Intelligent Design trial. Pharyngula has the trailer.

Why do people think the Earth is tilting wildly away from its normal 23.6-degree inclination? This madness almost debunks itself, but Phil gives it just the push it needs to tilt right over.

When the next generation of planet hunting space observatories get into orbit, they’re going to be analyzing the atmosphere of distant worlds. Pamela describes what they’ll be looking for.

Why bother with Mars when we could colonize Ceres instead?

Space Law Probe remarks on the 40th anniversary of the “Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, Including the Moon and Other Celestial Bodies.”

October 10, 2007December 26, 2015 by Fraser Cain

High Resolution Views of Potential Mars Landing Sites

Mission planners for the Mars Science Laboratory have quite a challenge on their hands. Where should they land the rover in 2010? They’ve got a whole planet to choose from. Well, they’ve narrowed the field of prospective landing sites down to about 30 intriguing candidates. And now NASA’s Mars Reconnaissance Orbiter has delivered high resolution images of each and every potential landing site… in colour!

We’ve got Spirit and Opportunity currently crawling across the surface of Mars. The Phoenix Mars Lander is on its way now. But when NASA’s Mars Science Laboratory arrives in 2010, the science is really going to get rolling. This SUV-sized robotic explorer will bring its own nuclear power source, and a suite of science instruments, giving it the range and capabilities to find life on the surface of the Red Planet.

But where should it land? The University of Arizona’s HiRISE team delivered 143 images captured by NASA’s Mars Reconnaissance Orbiter to the researchers this week, showcasing each location in false and enhanced colour.

Normally the spacecraft captures its images in black-and-white. It’s relatively simple to grab a single image of the Martian surface with one of its filters. When you’re trying to get colour, though, things become more complicated. The spacecraft moves so quickly above Mars that it’s very difficult to capture several images of the same area in different wavelengths of light and then merge them together into a single colour image.

Researchers with the HiRISE team have developed a computer program that can process data from different colour filters and merge them into a single image. Of course, to process each 20,000 by 50,000 pixel region can take several hours.

Mission planners for the Mars Science Laboratory will be meeting at a workshop later this month to try and narrow down the field of choices. These colour photographs will help them make a decision.

You can browse all the images yourself if you like. Click here to see them. You can also access the movie that pans across a potential landing site at Nili Fossae. The animation shows a range of enhanced colours that reveal rocks that might have been altered by water in the past.

Original Source: UA News Release

October 10, 2007December 26, 2015 by Fraser Cain

Expedition 16 is Off to the International Space Station

The next inhabitants of the International Space Station, Expedition 16, were blasted into orbit today aboard a Russian Soyuz rocket. On board are Malaysia’s first astronaut, Sheikh Muszaphar Shukor, veteran cosmonaut Yuri Malenchenko, and US commander Peggy Whitson – the first woman to ever command the station.

The Soyuz TMA-11 spacecraft blasted off from the Baikonur Cosmodrome in Kazakhstan today at 1322 UTC (9:22 a.m. EDT). It should take another two days for them to match orbits with the International Space Station; the docking is planned for Friday at 1452 UTC (10:52 a.m. EDT).

Once they do arrive at the station, they’ll begin the process of taking over responsibilities from Expedition 15. During their 6-month mission on the station, they’ll be busy to say the least. Three space shuttles are due to dock and continue construction of the station, and Europe’s first automated cargo ship, Jules Verne, will also visit during their mission.

Two members of Expedition 15, commander Fyodor Yurchikhin and flight engineer Oleg Kotov, will return to Earth with Malaysia’s Shukor on October 21st. NASA astronaut Clayton Anderson will remain onboard for the first stage of Expedition 16.

Original Source: NASA News Release

October 10, 2007December 26, 2015 by Fraser Cain

First Pictures From Kaguya

The Japanese space agency JAXA has confirmed that their lunar orbiter Kaguya (aka Selene) is now firmly in orbit around the Moon. That was quick. The agency released this image captured by Kaguya’s high-gain antenna motor camera showing its new home.

The spacecraft isn’t due to take photographs with its full suite of scientific instruments until it reaches its final science orbit later this month. This image was captured by the antenna motor, which just happens to have a view of the Moon in the background. Don’t worry, the images are going to get much, much better.

By the time Kaguya is in its final science orbit, it will be able to capture images of the lunar surface at a resolution of 1-metre. It will also be recording high-definition television images of the surface, which should look just amazing in the eventual documentaries.

Original Source: JAXA News Release

October 10, 2007January 24, 2021 by Fraser Cain

Astrosphere for October 10th, 2007

First, your photo for the day is of the Trifid Nebula, captured by JAICOA.

In Universe Today news, I’m testing out a new forum/blogging software called Lefora. This could be an eventual new home for Universe Today, or maybe it’ll be a botched experiment, quickly forgotten. To help me decide, please take a moment and come check it out at: http://universetoday.lefora.com/. Register as a user, comment on stories, start new discussions, post pictures, vote. And give your feedback. I’d really appreciate your help.

Now, onto the ‘sphere.

As a tribute for the 100,000th asteroid discovery, researchers have decided to rename it to Astronautica.

SPACE.com has a video of a potential asteroid mission.

Astronomy.com reports on the battle to save the Arecibo observatory.

Australian researchers are working on a design for a self-sufficient lunar colony.

Didn’t you think it was cool that Google redesigned its logo to celebrate Sputnik’s 50th anniversary? Not everyone did, apparently.

No, that’s not a big glass worm on the surface of Mars.

Remember the DARPA Grand Challenge, where robotic cars navigated a complex track? The urban version is about to begin. Robotic cars on busy city streets. I can’t wait.

And finally, Centauri Dreams remembers Robert Bussard, inventor of the ram jet that bears his name. He passed away from cancer a few days ago.

October 10, 2007December 26, 2015 by Nicholos Wethington

The Tiger Stripes and Geysers are Linked on Enceladus

Saturn’s moon Enceladus is one of the most peculiar objects in the Solar System. We now know there are geysers of water ice blasting from its southern pole; a place marked with long gashes that researchers have dubbed “tiger stripes”. Ever since the geysers were first discovered, scientists have been puzzling out their source. Now they understand how the geysers and tiger stripes are linked.

New research by the Cassini imaging team, CICLOPS, shows that the jets of Enceladus emanate from its southern pole, pouring out of four of the tiger stripes. The researchers have named them Alexandria, Cairo, Baghdad and Damascus. Of the four, Baghdad and Damascus are the most active and Alexandria is the least.

By taking Cassini’s two-year observations of the jets that spray from the surface, and combining this with thermal imaging of the stripes, the team was able to determine that the jets were spraying vertically out of the stripes, which are cracks on the surface of Enceladus.

The water sprays through the cracks because the gravity of Saturn pulls and pushes on Enceladus, and this motion – called a tidal force – heats up the frozen water underneath the surface. Much like geysers on Earth, the water is heated and expands below the surface, and follows the easiest path it can find to escape; this path happens to be right through the tiger stripes on the surface.

The researchers noted that when the tidal pull of Saturn was compressing this region of Enceladus, the geysers were not very active, if at all. But when the tides pulled and created tension, they began to erupt. Also, the hotter the region was, the stronger and larger the jet plume tended to be.

There may be other areas of Enceladus capable of producing jets, and now that the origins of the geysers are confirmed, more thermal and digital imaging of the surface could reveal other geysers in the future.

The researcher paper, entitled “Association of the jets of Enceladus with the warmest regions on its south-polar fractures” was published in the October 11th edition of the journal Nature.

Source: Nature