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Mars-approaching comet may alter Indian space mission plans

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Artists illustration of the Indian Mars orbiter Mangalyaan. Credit: ISRO

Call it an unfortunate coincidence. Indian scientists are concerned their Mars probe may arrive about the same time a comet blasts past the Red Planet.

There’s worry that the methane in the comet’s tail will give false readings on one of the probe’s instruments used to detect the gas in the Martian atmosphere. Methane, while intimately associated with living things like cows, people and bacteria, can also be produced by chemical reactions between water and rocks.

Comet C/2013 A1 is little more than a very faint fuzzy spot right now but should become visible in binoculars in 2014. This photo was taken on March 13, 2013. Credit: Joseph Brimacombe

Comet C/2013 A1 Siding Spring was discovered on January 3 this year by Robert McNaught of Australia. Once an orbit had been calculated, astronomers discovered that the comet would pass only about 93,000 miles (150,000 km) from Mars on October 19, 2014.

Photo illustration of a comet passing near Mars in 2014. Credit: Comet R1 McNaught by Michael Jaeger; Mars photo by Emil Kraaikamp; illustration: Bob King

The comet itself could be anywhere from a few miles to a few dozen miles across, but the tail and atmosphere it develops from heating by the sun could easily span hundreds of thousands of miles. Comet tails and their fuzzy shrouds called comas are made of dust and vaporized ices of water, methane, ammonia and carbon dioxide.

While the possibility of A1 hitting Mars is remote, the rarefied dust and gases in the comet’s head and tail could brush the planet’s atmosphere as the comet speeds by at some 35 miles (56 km) a second.

Orbit of Comet C/2013 shows its close approach to Mars in October 2014. Credit: Carl Hergenrother

Mangalyaan - Hindi of ‘Mars craft’ – is the first interplanetary mission of the Indian Space Research Organization (ISRO). The probe will study the composition of the Martian atmosphere, photograph the surface and map the planet’s minerals from orbit.

With an expected launch on November 27 and 9-month trip time, Mangalyaan  will arrive in late August before the comet makes its closest approach.

There’s talk, according to a recent article in the online India Daily News and Analysis, that some ISRO mission planners are considering alternative launch dates to prevent their methane-detector from giving false readings.

While I’m only an amateur astronomer it would seem to me that having the orbiter in place before the comet arrives would be a real boon. It could begin sampling atmospheric gases and then record the affects – if any – that the Siding Spring comet might introduce. In effect,  Mangalyan would serve as both Mars AND comet probe. Possibility it could even be re-directed for a time to photograph the comet from a spectacularly close distance.

We’ll wait to see what happens. Astronomers are keeping a close eye on this comet and refining exactly how close a pass it will make to the Red Planet. Stay tuned.

Bitter winter weather conjures visions of Saturn’s moon Titan

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Saturn’s moons Titan (larger) and Rhea area a study in contrasts. Rhea is icy, airless, crater-gouged and 950 miles across. Titan is 3,200 miles in diameter (about half again as big as our moon) and enveloped in a dense atmosphere of nitrogen with a haze of hydrocarbons. The orange color comes from tar-like substances that form when methane is bombarded by ultraviolet light from the sun. Credit: NASA / JPL / Space Science Institute

We’ve got bitter cold weather on the way here in Duluth, Minn. with highs predicted around -7 F (-21 C) and lows at night of -20 F (-29 C). What better time to drop in on an even colder place, Saturn’s largest moon Titan. There the average daily high is 290 below zero (-179 C). In those frigid conditions, gases like ethane and methane, of which this moon has an abundance, rain down from the clouds and pool into hundreds of lakes, rivers and seas. From an orbiting satellite, you’d think you were looking at an aerial view of northern Minnesota.

Radar image from NASA’s Cassini orbiter showing a network of lakes in Titan’s northern hemisphere.  Titan’s atmosphere, which is about 95% nitrogen and 5% methane (natural gas) gives the moon a surface pressure 1.6x that of Earth. Credit: NASA/JPL

With a surface pressure 1.6 times greater than Earth, Titan’s atmosphere is thick enough to allow liquid hydrocarbons to exist on its surface. It’s the only known body aside from Earth with great quantities of exposed fluids. As for water ice, yes, Titan has that too, but it’s as hard as rock in such a brutal environment.

How about a swim in Titan’s Sea of Ligeia? This body of liquid hydrocarbons (ethane and methane) with a surface area bigger than Lake Superior, is located in Titan’s Arctic latitudes, has been artificially colored blue. Rivers of methane have carved many channels around its periphery. Credit: Antoine Lucas, Oded Aharonson & The Cassini Radar Science Team, Caltech/JPL/NASA

A new paper by scientists on NASA’s Cassini mission finds that blocks of hydrocarbon ice might dot the moon’s lakes and seas. Their presence is inferred by mixed readings of the lakes’ reflectivity. This is an interesting premise since solid methane ice is denser than the liquid variety and would be expected to sink. But scientists discovered that methane ice will float if the temperature is below the freezing point of methane (-297 F) and the ice contains at least 5% air absorbed from Titan’s atmosphere. Click HERE to read more on the topic.


Titan descent video. At the end at touchdown, you’ll see the shadow of the parachute – amazing!

Eight years ago this week, the European Space Agency’s battery-powered Huygens (HOI-gens) probe entered Titan’s atmosphere after departing the Cassini “mother ship” 3 weeks prior. Huygen ejected its back shell and heat shield and floated down by parachute through the moon’s orange haze. Two and a half hours later it made a slippery-slidey touchdown on the surface. Scientists had hoped it would land in an ocean, since it was made to float, but instead the probe struck terra firma (Titania firma?).

The Huygens probe landed on a soft, sandy riverbed. The rocks you see are most likely made of water ice. Credit: ESA/NASA/JPL/University of Arizona

On the way down, Huygens transmitted pictures of its descent as well as photos from the surface. Networks of streams were seen from the air; on the ground, eerie ice boulders are visible near to far under an orange sky. If there were ever a place you’d call alien, Titan would be it.

I expect once the cold sets in, all the extra clothing we vulnerable humans will don will give the place a similar otherworldly look. Cold weather and plenty of atmosphere – two things Titan and Duluth have in common. Maybe we should consider starting a “sister planet” program.

Here are a couple more videos of Huygens’ descent to Titan including one where you can heard winds buffeting the probe and another showing a brand new animation re-creating the craft’s final descent and peculiar landing. Enjoy!


Simulation of how the probe landed based on data sent back by Huygens.  


The winds of Titan – listen to the sound

See the Spring Triangle and Saturn tonight

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The Spring Triangle stretches across the eastern sky around 10 p.m. last night. It's formed by the star Arcturus (upper left), Saturn (top right) and Spica (below Saturn). Photo: Bob King

I’m not the first to call it the ‘Spring Triangle’ but the name sure fits. We’re talking about Arcturus, Saturn and Spica and what a fine figure they cut in the eastern sky from 10 o’clock onward. I suppose it was inevitable given our fondness for triangles of bright stars that one should pop up in spring. You’re probably already familiar with the Summer Triangle and the Winter version, so why not one for spring?

Unlike the Summer and Winter standbys, this one’s only good for a year. That’s because one its members, Saturn, like the other planets, never stays put in one place. Next year the planet will have slid eastward and lie to the left of Spica. No triangle there. However, in 2013 it will be positioned below Spica and form a new, wider triangle with its starry pals.

The current triangle is huge, bright and really catches the eye. You can squeeze three fists held at arm’s length between Saturn and Arcturus. Spica and the planet are just a fist apart. Start your spring with this fun, connect-the-dots exercise tonight.

Cassini spacecraft chronicles the change of seasons as it captures clouds concentrated near the equator of Saturn's largest moon, Titan. This picture consists of an average of three images taken using a filter sensitive to near-infrared light, which 'see' through Titan's haze to its surface and lower atmosphere, plus an image in visible light. Credit: NASA/JPL/SSI

Speaking of Saturn and spring, we’ve already seen rain a few times here in Duluth, a welcome sign that the season is underway despite stubborn single-digit nighttime temperatures. Saturn’s largest moon Titan also experiences seasons, with changes in cloud cover depending on the season. Back in 2004, during late southern summer, the Cassini spacecraft photographed extensive clouds in Titan’s south polar regions.

The photo above was taken in October 2010, about a year into Titan’s southern fall, and shows a few clouds in the south, but most are now concentrated in a bright belt around the moon’s equator. The clouds may look familiar, but they’re composed of methane, the principle ingredient in the natural gas we use to heat our homes back here on Earth. Because Titan and Saturn are nearly a billion miles from the sun, it’s much colder there, allowing methane to exist as ice, liquid and cloud.

A huge arrow-shaped storm, measuring 930 by 750 miles, blows across the equatorial region of Titan last September. This storm darkened large areas of the moon, likely from methane rain. Credit: NASA/JPL/SSI

Scientists believe that methane evaporating from lakes on Titan’s surface rises to form clouds, which then release methane ‘rain’ during rainstorms, refilling lakes and creating new ones.

“It’s amazing to be watching such familiar activity as rainstorms and seasonal changes in weather patterns on a distant, icy satellite,” said Elizabeth Turtle, a Cassini imaging team associate at the Johns Hopkins University Applied Physics Lab in Laurel, Md.

Spring has been underway since 2009 in Titan’s northern hemisphere. Storm clouds in the photos above have swept over the moon’s equatorial regions and left what appear to be dark, methane rain-soaked ground and replenished lakes in their wake.

Clouds move above the large methane lakes and seas near the north pole of Saturn's moon Titan. The outlines and color of the lakes have been enhanced for clarity. Credit:Â NASA/JPL/SSI

Those lakes are even colder than those in my part of the world. Temperatures on the surface of the moon hover at -290 F. Titan has hundreds of lakes brimming with methane and ethane. Largest is the 150,000 square mile Kraken Sea, nearly five times bigger than Lake Superior! The moon may be an alien world, but it’s the first place beyond Earth where we’ve seen stable bodies of surface liquid.

Saturn and Titan tonight. The view shows directions reversed with south at top and east to the right, the way you'd see it in most telescopes. Created with Stellarium

You can see this wintry world for yourself in even a small telescope. Tonight Titan is at greatest elongation (maximum distance) east of Saturn. 25x and up will show it as a small ‘star’ four ring lengths due east of the planet. If you’re using an 8-inch or larger scope, you’ll even be able to see Titan’s orange color.

Those willing to invest a little more time can watch Titan move closer to Saturn over the coming nights. The moon completes an orbit around the ringed planet in 16 days.