There’s cold water vapor orbiting the star TW Hydrae… and a lot of it. Enough to fill the Earth’s oceans thousands of times over!

TW Hydrae is a star located pretty close by, about 175 light years away. It’s lower mass than the Sun, so it glows an orange-red, but it’s also very young, less than 10 million years old. Stars that age are still shaking off the remnants of their formation, and that’s just the time you expect planets to get started.

And in fact it’s been known for years that TW Hydrae is surrounded by a giant disk, the leftover materials from its formation. Disks like that around other stars have been closely scrutinized, and we see lots of different materials in these disks, including various minerals, complex dust molecules, and even water. In general the water that’s been found is usually close in to the star and warm (which makes it easier to see).

Astronomers used the orbiting Herschel telescope to look at the disk of the star TW Hydrae in the infrared, and found water in the spectrum of the material there. And what they discovered is that it’s cold vapor, not warm. That’s the first time this has even been seen, and it’s kinda neat how this was done.

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For the past few years, tantalizing evidence has been found that Mars — thought to be long dead, dry, and lifeless — may have pockets of water just beneath the surface. To be clear, we know there’s water on Mars, in the form of ice. We see ice in the polar caps, and we’ve seen it revealed under the surface by small meteorite impacts.

The question is, is there liquid water?

New images by the Mars Reconnaissance Orbiter bring us a step closer to answering that question. A series of pictures of the 300 km (180 mile) wide Newton crater taken over the course of several years show dark deposits on the crater wall which change predictably with the seasons, clearly affiliated with some sort of material flowing downslope:

[Click to barsoomenate.]

The picture above shows Newton’s crater wall. It’s pretty steep, with about a 35° slope, and the dark deposits are labeled. This crater is located in the southern mid-latitudes of Mars, and this part of the crater faces north. That’s critical! Since it faces toward the equator, that means it’s facing the Sun in the summer, and so these deposits appear when the temperatures get warm.

NASA has created several animated gifs (too big to embed here) that show the growth and retreat of these features over time. You can easily see how these dark features change.

In the past, similar things have been seen in gullies on Mars. It’s not clear those are from water, since frozen carbon dioxide can also be thawing out and forming them. In those cases, the flows were seen on the cold-facing sides of crater walls, making it less likely they’re from water. These new formations are on the warm-facing side, making it more likely they are from water.

So what’s going on? (more…)

Like any scientist, I love a good mystery. Sometimes it’s fun when they are long, complicated, involve subtle and difficult layers, and require a vast effort to unravel.

And sometimes it’s cool when they are simply stated and simply solved. Like asking "Where does the water in Saturn’s upper atmosphere come from?" and finding out the answer is "It rains down from the moon Enceladus."

Water has been seen deep in Saturn’s atmosphere before, but a few years back it was detected in the upper atmosphere as well, and that’s a bit weird; there don’t appear to be any ways to get it from deep down in Saturn to the top parts of its clouds. So how did it get there?

Well, the tiny, icy moon Enceladus was discovered to have geysers at its south pole, actively spewing out quite a bit of water into space. Most of it goes into space and is gone forever. Some actually forms a ring around Saturn called the E-ring, and some no doubt hits other moons. Generally, when a moon blasts stuff into space (like Jupiter’s moon Io does with its sulfur volcanoes) the material forms a big donut-shaped region around the planet. It was figured that Enceladus was doing the same thing with water around Saturn, but even the Cassini spacecraft, which is right there, couldn’t detect it. It’s pretty hard to sample.

But astronomers used Herschel, an Earth-orbiting infrared observatory, to observe Saturn. They found a peculiar feature in the infrared spectrum of Saturn, and realized it’s from this Enceladusian water torus. Apparently, about 3-5% of the water from Enceladus’s geysers falls on Saturn, literally raining down in sufficient quantities to explain the presence of the water detected in the ringed planet’s upper atmosphere.

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Scientists studying samples of volcanic glass from the Moon have made a startling discovery: there’s more water in them than was once thought. A lot more water. Not enough to go swimming or anything like that, but certainly enough to have affected the Moon’s geologic history, and potentially profoundly impact (haha — see below) our ideas of how the Moon formed.

The scientists looked at glass created in volcanic fire fountains, eruptions billions of years ago that left tiny (roughly the diameter of a human hair) grains of colored glass on the surface. These lay there for quite some time until 1972, when they were spotted by geologist Harrison Schmitt, who happened to be standing on the Moon at the time as part of Apollo 17. He brought them back to Earth for study.

In the ensuing decades technology improved quite a bit, and figuring out the contents of the glass beads has become a lot more accurate. In this new research, the scientists found (in 2008, actually, but their results are now confirmed) that the beads have a water content of about 750 parts per million, roughly equivalent to what you’d find in magma in the Earth’s upper mantle. That’s very surprising; many of the rocks on the Moon’s surface are very dry^*, which for years has led scientists to assume the Moon itself was very dry.

Even with subsurface water being found all over the Moon, it’s still surprising to see this water in the beads. Why?

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The comet Hartley 2 has come and gone, and the NASA mission EPOXI is also moving on after an exceedingly close flyby of the comet’s solid nucleus. The pictures we got were fantastic and beautiful… but their real power comes from coupling them with spectra.

In the picture above — an enhanced version of one of the images taken during the space probe’s flyby — you can see fan-like emission coming from the comet’s nucleus. These are jets; sprays of material coming out of the nucleus. Comets are made of rock and ice, and when the comet nears the Sun, the heat can turn that ice directly from a solid to a gas. This gas then shoots out from pockets on the nucleus, creating these jets. The EPOXI team (including my old boss, Don Lindler!) made a fantastic animation from a series of observations showing these jets in action.

But what are these ices made of? Lots of things we normally think of as liquids or gas (water, ammonia, carbon dioxide, and so on) exist in comets. In many comets, we see lots of water, and in fact the Swedish satellite Odin detected about 200 kg/sec (440 pounds per sec) of water coming off Hartley 2! So is water powering these jets?

We can find out… using spectra. By breaking up the light from an object into its component colors, we can learn all manners of things including what it’s made of. EPOXI did just that with the jets streaming from Hartley 2, and while it did find water, amazingly, it found a lot more carbon dioxide!
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Does liquid water still flow on Mars?

We know that in the distant past — like, a billion years ago — liquid water was abundant on Mars. We also know that water currently exists on Mars in the form of ice, sometimes just below the surface (where even small meteor impacts can reveal it). But can there still be liquid water flowing on Mars, even if only for a very, very short time?

Maybe. Just maybe.

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NASA has found a significant amount of water ice on the Moon!

Holy Haleakala!

On October 9, the LCROSS spacecraft watched as a Centaur rocket booster slammed into the south pole of the Moon, hoping to determine if any water ice exists under the lunar surface. The idea is that over millions of years, comet impacts and other events have brought water to the Moon. Most of it goes away over time, but if any water happens to accumulate at the bottoms of craters at the poles, where the Sun never shines, it can stay put, frozen forever in shadow. By impacting a spacecraft into the Moon, it can eject the ice where it gets hit by raw sunlight. The water breaks down into hydrogen and hydroxyl molecules (OH-), which can be directly detected.

The target crater, Cabeus, has a temperature on its floor of -230 Celsius, cold enough to store ice. The Centaur slammed into it at high speed, making a new crater about 20 meters across and splashing debris over an even bigger area. A plume went up and out of the crater, and it was that tower of ejected material that had the telltale signs of water. The infrared spectrometer on LCROSS definitely detected absorption lines from water, and the ultraviolet spectrometer saw it in emission. Not only that, the emission got stronger with time, which clinches the deal! That’s exactly what you expect by a plume containing water.

Wow.

The amount of water they found in the plume was a couple of hundred kilograms in total, but that indicates there is a lot more still lying on the surface. They don’t know how much exactly just yet; NASA wanted to release this news as soon as they were sure they had definite results, but there is still much to do. Where did this water come from? How long has it been there? How accessible is it to future astronauts? These questions and more will, hopefully, be answered in the coming weeks and months as the data are analyzed more thoroughly. So stay tuned. There’s lots more good news to come!