Posted on by Fraser Cain

Underground Oceans Discovered on Titan

With each flyby, NASA’s Cassini spacecraft has been building up the case that there are lakes and seas of liquid hydrocarbons on the surface of Saturn’s moon Titan. But now we get the stunning news that the planet might have vast oceans of water and ammonia underneath its surface as well.

Over the course of 19 separate Cassini Titan flybys, members on the mission science team carefully established the position of 50 unique landmarks on the surface of the moon. After each flyby, they located the landmarks again, and marked their positions.

During nearly 2 years of flybys, from October 2005 to May 2007, surface features had moved from their original positions by up to 30 km (19 miles). The only way the surface could be shifting like this is if the moon’s icy crust is floating atop an internal ocean.

“We believe that about 62 miles beneath the ice and organic-rich surface is an internal ocean of liquid water mixed with ammonia,” said Bryan Stiles of NASA’s Jet Propulsion Laboratory (JPL) in, Pasadena, Calif.

Since Titan has an incredibly thick atmosphere, 1.5 times more dense than the Earth, it’s possible that powerful winds are rocking the moon back and forth around its axis. It might be speeding the rotation up at one point in the year, and then slowing it back down again. But this would only be possible if there’s an ocean underneath the surface that the entire crust floats on top of.

“The combination of an organic-rich environment and liquid water is very appealing to astrobiologists,” said Ralph Lorenz, lead author of the paper and Cassini radar scientist at the Johns Hopkins Applied Physics Laboratory in Laurel, Md. “Further study of Titan’s rotation will let us understand the watery interior better, and because the spin of the crust and the winds in the atmosphere are linked, we might see seasonal variation in the spin in the next few years.”

Researchers will get another chance to test their theories shortly. Cassini is due to make another Titan flyby on March 25th, at an altitude of only 1,000 km (620 miles).

The research will be published in the March 21st issue of the journal Science.

Original Source: NASA News Release

Posted on by Fraser Cain

Geologist Finds a Meteorite Crater in Google Earth

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Want to discover an impact crater, and even get it named after you? All you’ve got to do is spend a few (hundred) hours poring over images in Google Earth or Google Maps. That’s exactly what Geologist Arthur Hickman did, turning up a previously unknown impact crater when he was searching for iron ore in the mountains of West Australia.

While he was browsing through images on Google Earth, Hickman’s geology training helped him recognize the circular shape and raised rim of an impact crater. He sent a screenshot and coordinates to colleagues at Australian National University, and they confirmed that it’s a well-preserved meteor crater between 10,000 and 100,000 years old. And until now, totally unknown.

You can take a look at the crater for yourself on Google Maps.

This isn’t the first time a crater has been discovered using Google Earth. One was found in the Saharan Desert two years ago. That crater is 31 km (19 miles) across – much bigger than Meteor Crater in Arizona.

The newly named “Hickman Crater” measures 270 metres (885 feet) across, and is about 35 km north of Newman, Australia. The region was mapped by the Geological Survey of Western Australia about 20 years ago, but the crater went unnoticed until now.

Since large meteorites hit the Earth every few thousand years, and when you consider that the landscape is millions of years old, there are many regions hiding meteorite impacts.

They’re just waiting for you to find them.

Original Source: ScienceAlert

Posted on by Fraser Cain

Organic Molecules Seen in an Extrasolar Planet

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The Hubble Space Telescope has turned up evidence for organic molecules on a planet orbiting another star. Organic molecules? Like the stuff we’re made of? Yes, but wait, this isn’t the discovery of life. In fact, it’s just the tell-tale signature of methane in the atmosphere of a distant, superheated planet.

The Jupiter-sized extrasolar planet is called HD 189733b, and it orbits a star about 63 light-years away in the constellation Vulpecula. Astronomers discovered that the planet is a member of the “hot Jupiter” class of planets, orbiting so close to its parent star that it only takes 2 days to complete an orbit.

This close orbit, much closer than the orbit of Mercury, raises the planet’s temperature to a sweltering 900 degrees Celsius – about the same temperature as the melting point of silver.

Here’s a computer animated video of the planet.

The observations were made using the transit method. This is where the planet passes directly in front of the parent star from our perspective. As it passes in front, it dims the light from the star slightly. And there’s a special bonus. As the planet is making this transit, astronomers can measure its atmosphere.

Using a technique called spectroscopy, the astronomers were able to split the light coming from the planet to reveal the fingerprints of various chemicals in its atmosphere. They confirmed the existence of water, turned up by NASA’s Spitzer Space Telescope back in 2007. But now they also found methane.

Under the right circumstances, methane can play a key role in prebiotic chemistry – the chemical reactions considered necessary to form life as we know it. Methane has been discovered in other planets in our own Solar System, so it doesn’t mean there’s life on HD 189733b (especially with its extremely hot temperatures). But finding methane around another planet, orbiting another star is an exciting advancement.

So even though life is out of the question on HD 189733b, the technique is the major news here. Astronomers will eventually be peering at smaller, more Earth-sized planets, and will be using this method to find other chemicals of life within stellar habitable zones.

If the life’s out there, astronomers are getting closer and closer to finding it.

The discovery was published in the March 20th issue of the journal Nature.

Original Source: Hubble News Release

Posted on by Fraser Cain

Arctic’s Oldest and Thickest Ice is Melting Away

It’s been a strange year for the Arctic. During the summer, high temperatures melted away vast regions of the Arctic sea ice, opening up the Northwest Passage for the first time. But then this winter has been unusually cold, bringing back large large areas of sea ice. So what’s going on? Is the Arctic recovering, or is Global Warming marching on?

The big problem studying global warming is that the temperatures and local climate can fluctuate. Over the short term, in some regions, you can have unseasonably warm or cold temperatures. Here in Vancouver, we had one of the coldest, snowiest winters I’ve ever seen.

NASA scientists are measuring the long term trends for the ancient perennial sea ice that lasts across several seasons. And this ice seems to be melting away over the years. In the past, this perennial sea ice – anything that lasted more than a single year – covered 50-60% of the Arctic. This analysis was made by NASA’s ICESat satellite, which measures sea ice thickness with microwaves.

This year, the perennial sea ice covered only 30% of the Arctic. And the most ancient ice, that which has survived more than 6 years, used to comprise 20% of the Arctic. Now it’s down to just 6%.

As this year shows, Arctic sea ice doesn’t stand still. Its coverage grows and declines seasonally, reaching the maximum in March, and the minimum in September. And this year, the maximum is up 3.9% over the previous 3 years. At the same time, the perennial sea ice coverage is down to an all-time minimum.

As the perennial sea ice thins, it’s more vulnerable during the summer melt period to wind and waves. Large chunks of ice can be carried out of the Arctic to melt in warmer waters.

Don’t worry about water levels rising as the sea ice coverage disappears. This ice is already in the water, displacing the same amount. So as it melts, sea levels should stay right where they are. That’s different from the ice locked up in the world’s glaciers, Greenland, and the Antarctic ice cap. As those melt, sea levels will rise.

To better understand the Arctic ice coverage, NASA is planning to launch a follow-on mission called ICESat II, due for launch in 2015.

Original Source: NASA News Release

Posted on by Fraser Cain

Preventing Pearl Harbor in Space

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Both China and the United States have recently demonstrated their ability to reach out and destroy satellites from the ground. Since the modern military depends so much on satellites for communications and reconnaissance, you can imagine they’re juicy targets in future conflicts. Aviation Week has an interesting article about the US Air Force’s strategy to defend against this.

So here’s the nightmare scenario. One country planning to invade another would launch a simultaneous attack against a constellation of satellites. If the attacker timed things right, and launched enough anti-satellite missiles, the defender would be rendered blind almost instantaneously.

One moment, the Pentagon is watching the Earth from multiple vantage points, coordinating the movement of troops, and a few minutes later… nothing. A 2001 Space Commission called this scenario, “Pearl Harbor in Space”.

The Pentagon is working on a strategy they hope will prevent against this sneak satellite attack, and they hope to have it online by 2011. The new system, called Rapid Attack Identification Detection Reporting System (Raidrs), would upgrade the capabilities of the satellites, as well as put in a ground-based monitoring system. As missiles are launched towards satellites, commanders would have enough warning to move the targeted bird out of the way.

If the attack came today, the US military would know they were being targeted, but they wouldn’t necessarily know where, or from who. And they’d have no way to prevent satellites from being shot down. But within a few years, that should change, with individual satellites able to be defend themselves, and help pinpoint the attacker.

As we move ever forward into the space age, we bring our military with us. Although it would be wonderful to have space without weapons, I can’t imagine why the world’s military wouldn’t want to come along into the final frontier. Space is the ultimate high-ground, and they’ll do everything to defend it. Just imagine how many science probes all this military spending would buy.

Anyway, check out the Aviation Week article, and get more details about the program itself.

Posted on by Fraser Cain

Satellite Fails to Reach Proper Orbit

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Just a quick piece of sad news. SES Americom reported that its AMC-14 satellite failed to reach its orbit on Saturday after it was launched by a Russian Proton Breeze-M rocket. Despite the failure, though, there might be hope that the satellite will be broadcasting HD television eventually.

The company said that the problem happened during the second burn of the fourth stage, and resulted in the satellite – built by Lockheed Martin – not reaching its geostationary transfer orbit.

With this failure, the company has suspended plans to ship the next satellite to the launch site, and its April launch will be postponed until a thorough investigation can be done. Dish Network was originally planning to lease the entire capacity of the satellite to increase the number of high-definition television channels that it broadcasts. They were planning to launch three new satellites in 2008.

It’s not a hopeless situation, however. SES Americom president Edward Horowitz said he’s working with Lockheed Martin engineers to figure out a way to get AMC-14 back into its correct orbit. The downside is that the fuel used to get the satellite into its proper orbit will shorten its broadcast lifetime, since it’ll have less fuel for station keeping.

Original Source: SES Americom News Release

Posted on by Fraser Cain

Godzilla Wakeup Call

This is hilarious. You know how NASA beams up a morning wakeup song to the shuttle astronauts on every mission. They decided to go with a giant radioactive lizard theme song for Day 3 of the mission. Japan Aerospace Exploration Agency Astronaut Mission Specialist Takao Doi, and the rest of the astronauts were awoken on Day 3 by this terrifying monster attack on Tokyo.

Posted on by Fraser Cain

Advertise on Universe Today, Astronomy Cast, and Other Space Sites

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Just in case there are some marketers out there, I wanted to let you all know that you can advertise here in Universe Today, in the Astronomy Cast podcast in the Bad Astronomy/Universe Today forum and other places. If you’re wondering how you can reach almost a million space enthusiasts every month, check out the advertising page. Great demographics and competitive rates. And it’s not just banner advertising either, we can come up with all kinds of clever ideas to help you reach the right audience, including giveaways and interactive programs. Drop me an email at [email protected] with your needs and I can get back to you with some ideas.

Posted on by Fraser Cain

Life Thrived After More Than 100 Meteorites Struck the Earth

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Yesterday we talked about the discovery of amino acids in meteorites. And then today comes news that there was an explosion of life (pardon the pun) after meteorites rained down more than 400 million years ago. Even though the Earth was struck by more than 100 1-km meteorites in a short period of time, life not only survived, it thrived.

The string of impacts occurred during the Ordovician period, between 490-440 million years ago. It wasn’t quite life as we know it, but creatures were living on land, and organisms had evolved to fit every niche in the oceans.

According to planetary scientists, a disruption in the asteroid belt about 470 million years ago sent hundreds of space rocks out of their normal orbit, and into ours.

Over a few million years, more than 100 separate meteorites larger than 1 km across struck the Earth, throwing up a Sun-clogging shroud of dust. Plants, starved for sunlight, died, and the chains of life depending on them collapsed.

But incredibly, life thrived after this period, evolving into new and interesting life forms.

Researchers from the University of Copenhagen and Lund University gathered together chemical samples from meteorites, fossils, and examined several craters in Sweden. The Lockne crater, for example, is located in northern Sweden and has a diameter of 7.5 km across.

They found evidence for the thriving life forms in layers newer than the ones containing debris from the meteorite strikes.

“You could say that biological evolution experienced a serious boost within a relatively short period of time. And, as is the case with, for example, volcanic eruptions or large forest fires, the impacts initially had a devastating effect on all life, but from the ashes arose a much richer fauna than had existed previously,” said Dave Harper from the University of Copenhagen.

This is research we’ve seen before. Paleontologists announced earlier this year that life can bounce back quickly from an extinction event, but it takes a long time for the true diversity of life to reappear. So, after most life is wiped out by an asteroid, the cockroaches and rats take over. You might have the same number of creatures, but it takes many years before you get rich ecosystems with butterflies and giraffes too.

Original Source: Nature Geoscience

Posted on by Fraser Cain

Making the Best First Impression, with Aliens

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Did you know the SETI Institute has a Director of Interstellar Message Composition? I did not know that. I guess it makes sense. If we’re going to be communicating with aliens, we’ll want to be careful about the words we choose. Get it right, and we’ve got extraterrestrial friends, here to uplift us to the galactic community. Get it wrong and we might be looking at radio silence, or worse…

So how should we present ourselves to prospective galactic neighbours?

Douglas Vakoch, the aforementioned Director of Interstellar Message Composition at the SETI Institute has done some thinking about this, and recently wrote it up in an article entitled, How we Present Ourselves to Aliens.

The trick, of course, is to make a good first impression. When the aliens finally receive our first communications, we want them to be wowed. But should we hide our more violent tendencies, or is the best strategy to just be honest. Sure, we fight a few wars here and there, but that’s just a phase we’re working through.

Vakoch thinks that honesty is the best policy. Sure we’re flawed, but what member of the Milky Way club didn’t ravage society with constant warfare and nearly destroy their environment before they reached perfection?

The aliens might be touched at our honestly, recalling their own struggle to get to a stable, peaceful society. Or they might just send in the berserkers to wipe the violent apes off the planet.

And how should we communicate? Could we just transmit CAT-scans of the human body, demonstrating both our physique and level of technology. Or should the mathematicians do our talking for us, communicating in terms of pi until we’ve a mutual mathematical appreciation happening. Do we send our beautiful music, hoping their like it? But what if they hate it?

Whatever we say, and however we say it, that first impression is everything.

So let me know. What would you say, and how would you say it? And if the aliens actually replied, what would we do then?

Original Source: SETI Institute