We’re on the comet, baby! Philae scores a touchdown

Rosetta team members, including  Flight Director Andrea Accomazzo (left), react to the first signal received from the Philae lander after its successful touchdown on Comet Churyumov-Gerasimenko earlier this morning. Credit: ESA

Around 9:37 a.m. (CST) Philae successfully landed on craggy comet Churyumov-Gerasimenko. The first signal, a voice from another world, arrived at 10:05. While the lander reached the surface in good health and continues to send telemetry, a small problem cropped up. The two harpoons that would anchor the craft to the comet failed to fire.

Check out this James Bond-style Swiss Army knife of a lander. Each instrument includes a short description. To read clearly, click for a large version. Credit: ESA

Right now, mission control is considering whether to re-fire them as well as figure out why they didn’t fire in the first place. In the comet’s low gravity, it’s important that Philae be sitting stably. Just think what would happen if a nearby jet erupted or ice began to vaporize around or under the craft? Weighing only a gram, Philae might easily tip over.

Here we come! The photo was taken by Philae at 8:38 a.m. (CST) when it was just 1.8 miles (3 km) above the comet. Credit: ESA/ESA/Rosetta/Philae/ROLIS/DLR

Hopefully we’ll see that first panoramic landscape photo soon. In the meantime, scientists held a press conference this afternoon to share first results as well as some of the troubles the lander faces.

Although Philae landed right on target and is gathering scientific data at this very moment, there have been problems with the radio link. Communications drop in and out for some as-yet unexplained reason. We know that neither the top rocket thruster (used to push the probe to the surface) nor the harpoons fired to anchor the craft to the comet’s surface. The data even seem to indicate that the lander may have even lifted off the ground and landed again:

Just to give you a flavor for the rugged landscape Philae was headed toward earlier today, this photo was taken by Rosetta at an altitude of 4.8 miles (7.7 km) from the comet’s surface. Credit: ESA

“Maybe today we didn’t just land once. We landed twice!” said Stephan Ulamec, Philae Lander Manager. Much is still preliminary, which is why the agency’s scientists are hard at work on the problem. Another live webcast is scheduled tomorrow at 7 a.m. (CST).

Live updates can be had on Twitter and the Rosetta website.

Philae descends to the comet, landing expected soon

The “farewell photo” taken by the Philae lander as it departed Rosetta around 2:30 a.m. (CST) today. It shows the one of the solar arrays on the spacecraft. Credit: ESA/Rosetta/Philae/CIVA

So far, so good. The European Space Agency’s Philae lander, a box of science instruments the size of a dishwasher, is now free-floating to the surface of Comet Churyumov-Gerasimenko and expected to touch down shortly. Lots more updates coming! Be sure to also check the mission’s Twitter feed.

The lander with its legs popped open photographed during its descent to the comet by Rosetta. Credit: ESA/Rosetta/MPS for Rosetta Team

Guess who’s up before midnight? By Jove, it’s Jupiter!

Brilliant Jupiter now rises in the northeastern sky before midnight. The waning gibbous Moon will join the planet Thursday November 13th. This map shows the sky facing east at midnight in mid-November. Stellarium

If the sky’s seemed devoid of evening planets of late, you’re right. Mars still hangs on in Sagittarius, but it’s so low and sets so early, few notice. Most telescopic observers have long since abandoned the planet. With an apparent diameter of three-one-thousandth’s that of the Moon, it’s just too tiny to eke out any details.

Venus is also “officially” an evening planet but still much too close the Sun to view. Enter Jupiter. This jolly bright planet joins the evening crew with a bright flourish, rising in Leo the Lion. In the days of Daylight Saving Time it rose around 1 a.m. but now catches our eyes a little before midnight low in the northeastern sky.

Jolly Jove on November 8, 2014. The two big stripes are the North (top) and South Equatorial Belts. The Great Red Spot is seen along with a cluster of smaller oval storms. Credit: Christopher Go

Earth’s revolution around the Sun causes the stars and planets in the eastern sky to rise 4 minutes earlier each evening, while those in the west set 4 minutes earlier. Over time, stars in the west get pushed out of the way as those in the east rise higher and take over the sky. It’s the astronomical equivalent of seeing each older generation swept away by the little babes whose job it is to replace us.

My point is that Jupiter, while low now, will rise an hour earlier by Thanksgiving  (16 nights x 4 mins. = 64 minutes) and nearly 3 hours earlier by Christmas. We’re soon to see a lot more of this planet. So goes the cycle of the sky.

Three of Jupiter’s four bright moons will be visible in small telescopes tonight. This view shows them around midnight (CST) tonight. North is up. Stellarium

Not only is Jupiter a pleasure to see with the naked eye – it’s so darn bright – but its dynamic weather and four bright moons offer telescope users something new to see every time we look through the eyepiece.

Because Jupiter’s 11 times larger than Earth, it presents a huge disk compared to most planets. Even with a 3-inch scope you can watch the moons shuttle back and forth and spy the largest clouds belts. The Great Red Spot, an enormous hurricane-like storm, has been shrinking over the last decade but can still be spotted in 6-inch and larger instruments.

The 2014-2015 apparition of Jupiter is special because Earth crosses through the planet’s orbital plane. Since the four brightest moons orbit almost exactly around Jupiter’s equator, we’ll get to see them eclipse and occult one another. Eclipses are especially interesting to watch – over a few minutes time you can actually watch a moon temporarily fade away. I’ll have more on these fascinating events soon.

Cloudy? Snowy? That won’t stop you from seeing THIS aurora

Aurora flyover in high-def video from the International Space Station

Wish it had been clear at dawn this morning. Some of us would have seen a very nice aurora. As predicted, Earth’s magnetic bubble got slammed by a package of high-speed solar wind overnight that fired up the northern lights. The impact continues to reverberate with more activity expected tonight.

No matter the weather or circumstance, I think you’ll enjoy this high-definition video taken from the International Space Station. The curls, rolls and flashing purple flames are, well, incredible. And there’s nothing quite like looking down on the aurora from an altitude of 250 miles (402 km). As the camera pans, you’ll also see the delicate green film of airglow, which is distinct from the northern lights – airglow surrounds the entire planet like a membrane around a cell.

Green, streaky airglow seen from the ground on July 22, 2014. Its faint light is half the reason you can always see around on even the darkest nights. The other light is provided by the stars. Credit: Bob King

Ultraviolet light from the daytime sun ionizes or knocks electrons off of oxygen and nitrogen atoms and molecules; at night the electrons recombine with their host atoms, releasing energy as light of different colors including green, red, yellow and blue.  The brightest emission, the one responsible for creating the airglow so often seen in space station nighttime images and videos, stems from excited oxygen atoms beaming emerald green light.

Forget about the clouds and take a ride with the astronauts where it’s forever clear.

Aurora alert tonight through Monday night Nov. 9-10

Aurora smolders beneath the Big Dipper tonight November 9th around 7 p.m. Credit: Bob King

Around 7 p.m. this evening, just before moonrise, a smoky green glow fired up beneath the Big Dipper low in the northern sky. The Moon rose and clouds soon followed, but we might be in for a couple nights of northern lights.

Cirrostratus clouds at moonrise this evening refracted moonlight into a pretty halo. Caught in the semi-circle is the Hyades star cluster (lower right). The Pleiades are at upper right. Credit: Bob King

A coronal mass ejection that launched from the Sun on November 7th will arrive overnight and could produce minor to moderate (G1-G2) geomagnetic storms now through midnight Monday night. The strongest activity is expected between 3-9 a.m. (CST) tomorrow morning.

A blast of high-speed electrons and protons from the Sun on November 7 looks like it may affect Earth overnight and into Monday. Credit: NASA/ESA

Tonight’s little taste will hopefully be a sign of more to come.

Philae primed for this week’s first-ever comet landing – here’s what to expect

The Tale of Rosetta and Philae and their adventures at Comet Churyumov-Gerasimenko

Comet Churyumov-Gerasimenko’s got a big week in store. On Wednesday November 12 at 10:02 a.m. (CST), it welcomes its first visitor in over 4.5 billion years – a jukebox-sized emissary from Earth named Philae (FYE-lee or FEE-lay).

Philae will land at Site J on the comet since renamed Agilkia, an island in the Nile River. Philae temple was moved there after the building of the Aswan dam flooded Philae island, the location of an inscribed obelisk that helped break the code of the Rosetta Stone and later chosen for the lander’s name.

Simulation Philae’s 7-hour descent to the Agilkia landing site.

The final decision on a go-no go for landing will be made at 1:35 a.m. Wednesday. If everything proceeds as planned, Philae’s instruments will be activated and the probe will separate from the mother ship Rosetta an hour and a half later and descend 14 miles (22.5 km) to the comet’s surface at a walking pace. While Philae tips the scales at 220-pounds (100 kg) in Earth’s gravity, it will weigh only a gram or about as much as a paper clip on the comet.

During the descent, Philae will snap some photos of the landing site. Immediately upon landing, the forward Active Descent System (ADS) thruster located on top of the lander will fire for about 15 seconds to push the probe toward the surface. That’s to make sure it doesn’t rebound on contact with the ground. Harpoons will then be fired to secure it to the surface. All this happens at 10:02 a.m. (CST).

Timeline for Philae’s descent and landing.  Each of the acronyms is the name of an instrument that the lander will use to either photograph or study the comet gas and dust emissions, magnetic field, etc. Click to see a detailed, blow-by-blow timetable. Credit: ESA

Just 5 minutes after landing, Philae will take its first photos of its new home site and transmit them back to Rosetta. Science operations and uploading of data gathered during the descent as well as the first surface measurements will also begin. The robot’s mission will last at least a week, but could continue for months. Here’s what the Rosetta website has to say:

A rare glimpse at the dark side of Comet 67P/Churyumov-Gerasimenko. Light backscattered from dust particles in the comet’s coma reveals hints of surface structures. This image was taken by the high-resolution OSIRIS camera on September 29th from a distance of approximately 12 miles (19 km). The white flecks may be comet dust or cosmic ray hits on the detector. Credit: SA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA

“During the first 2.5 days the first series of scientific measurements will be completed. During this phase the lander will operate on primary battery power. In a second phase that may last up to three months, a secondary set of observations will be conducted, using backup batteries that will be recharged by the energy from the solar cells on the lander. However, no one knows precisely how long the lander will survive on the comet.”

Comet 67P/C-G on November 4th. Vaporizing ice creates the jet of material you see at right. Rosetta has detected water and carbon dioxide at the comet and also measured its current average surface temperature – chilly -57 F (-70 C). That’s a few degrees warmer than Minnesota’s record low of -60 F in February 1996. Credit: ESA/Rosetta/NAVCAM

This all assumes the craft will survive the landing. No one’s ever attempted to set down on a comet. We know there’s dust, ice, rocks and very little gravity. I’ll be biting my fingernails until we know the Philae’s sitting upright and transmitting those first photos.

NASA will cover the event live from 8 -10:30 a.m. (CST) Wednesday; ESA will also stream the landing around the same time.

Stay tuned – Wednesday will be here soon!

Spectacular meteor storm lights up Mars during recent comet flyby

On October 19, when Comet C/2013 A1 Siding Spring flew just 87,000 miles from Mars, dust from its tail set the sky aglow with a meteor storm. This illustration is my feeble attempt to show what you might have seen standing on Mars next to the Curiosity rover at the time. Credit: NASA (background) with additions and changes by Bob King

Oh, to have stood under the Martian sky on October 19th! As Comet Siding Spring passed just 87,000 miles (140,000 km) from the planet that night, dust in its tail slammed into the Martian atmosphere at 126,000 mph, burning up in storm of meteoric madness. “Thousands per hour fell,” said Nick Schneider, instrument lead for NASA’s MAVEN Imaging Ultraviolet Spectrograph. It must have looked like those classic illustrations of the 1833 and 1866 Leonid meteor storm back here on Earth.

Composite image of Comet Siding Spring and Mars taken by the Hubble Space Telescope. The images have been added together to create a single picture to illustrate the true distance or separation (1/20th the apparent size of the Full Moon) between the comet and Mars at closest approach.  Credit: NASA/ESA

I participated in a teleconference yesterday with principal investigators for the instruments on the Mars Reconnaissance Orbiter (MRO), MAVEN and Mars Express spacecraft pressed into service to study Comet Siding Spring during its historic flyby. The comet is a visitor from the faraway Oort Cloud, a spherical repository of billions of icy comets up to 1 light year from the Sun. Some 4-5 Oort Cloud comets swing through the inner solar system every year; this is the first one we’ve ever studied up close. It was discovered at Siding Spring Observatory in Australia by Robert McNaught on January 13, 2013.

NASA’s MAVEN uses its IUVS to perform a scan of the Martian atmosphere along its limb. Scans found enhanced levels of metals from vaporizing comet dust. Credit: NASA

“Dust slammed into the atmosphere and changed the chemistry of the upper atmosphere,” said Jim Green, director, Planetary Science Division, NASA Headquarters in Washington. Data from MAVEN’s UltraViolet Spectrograph (IUVS), which scans of Mars’ upper atmosphere in UV light to determine its chemical makeup, saw big spikes in the amount of magnesium and iron during the flyby. These elements are commonly found in meteorites.

Before and after scans by MAVEN. At left is a profile of the atmosphere before the comet’s arrival showing carbon dioxide and other gases; at right is during the comet’s pass. Check out that huge spike to the right – that from magnesium. Elevated levels to the left indicate iron. Credit: NASA

Siding Spring turned out to be much dustier than expected, prompting Green to later add: “It makes me very happy hid them (spacecraft) on the backside of Mars.” “It really saved them. Even one well-placed hit from a high-speed dust particle could damage an instrument, and Siding Spring peppered the Martian atmosphere with “several tons” of dust.

MAVEN used its mass spectrometer – an instrument that identifies elements by how much mass they have – to record a big enhancement of the elements magnesium, manganese, iron and others from comet dust in Mars’ atmosphere. Credit: NASA

Meanwhile, MAVEN’s Neutral Gas and Ion Mass Spectrometer (NGIMS), picked up major spikes in 8 different metals from ablating comet dust including sodium, magnesium, iron and nickel. Jim Green pointed out that the increase in sodium may have tinged the twilight sky with a yellow glow. That and a recent increase in the amount of dust in the atmosphere over the Curiosity rover site may be the reason the comet was so difficult to photograph from the ground.

Only hours after Comet Siding Spring’s closest approach, dust particles hitting air molecules on Mars formed a temporary ionized (electrified) layer in its lower ionosphere 50-60 miles high. Credit: ESA

So we have a very dusty comet, a big meteor storm, the atmosphere spiced up with metals from burning dust.

Anything else? Heck, yes. The European Space Agency’s Mars Express Orbiter used its radar to send out radio waves of very low frequency down through Mars atmosphere to record the state of the ionosphere, a rarified layer of air between 60-250 miles (100-400 km) high. At the comet’s closest approach, the ionosphere was normal, but 7 hours later, impacting dust had created a brand new, temporary ionization layer.

Close-ups pictures taken by the Mars Reconnaissance Orbiter of Comet Siding Spring around the time of closest approach to Mars. They show the combined light of the tiny nucleus and much larger coma or comet atmosphere. Comet dust / rocks range in size from 1/1000 of a millimeter to 1 centimeter (~1/2-inch). Credit: NASA

The high resolution camera on the MRO photographed brightness variations in the comet’s light, nailing down its rotation period to 8 hours. But size-wise, we’re a little less clear. Estimates for the comet’s nucleus range from 984 feet to 1.2 miles (300-m to 2 km). For comparison, Comet 67P/Churyumov-Gerasimenko, currently orbited by Europe’s Rosetta spacecraft, is 1.5 miles (2.4 km) across.

Color variations in this photo by CRISM indicate different sized dust particles being ejected by the comet. Credit: NASA

Yet another instrument named CRISM (Compact Reconnaissance Spectrometer for Mars) made some intriguing measurements of the coma showing distinct differences in color – red here, blue there – indicating the comet is blowing out dust particles of different sizes.

As scientists continue to analyze the data collected by the fleet of space probes, we’ll see more papers and results soon. For now, the rare opportunity to study a comet up close from another planet was an unqualified success. You can listen to the replay of the hour-long conference HERE.

Beauty at 225 below – a visit to Mars’ south pole

Black and white photo taken on September 10th and released this week by the Mars Odyssey spacecraft showing ice layers at Mars’ south pole. The image is 10.5 miles (17 km) across. Credit: NASA/JPL/ASU

Beautiful, isn’t it? You’re looking at multiple layers of water and carbon dioxide ice mixed with dust built up over millions of years at the south pole of Mars. Each layer or “step” varies in thickness from about 30 to 100 feet; together they make a stack up to 2.3 miles (3.7 km) high.

Mars permanent south polar cap measures about 250 miles (400 km) and consists primarily of water ice. During the southern winter, carbon dioxide in Mars’ atmosphere condenses as frost and falls as snow, whitening the planet’s southern hemisphere to latitude 50º south. Much the same happens on Earth during the winter months when snow covers the ground to across the northern and central U.S. and Canada.

The layers in these cliffs show buried ice deposits in the southern polar region of Mars at about 72°S. The image was obtained by Mars Express on January 15, 2011. Credit: ESA/DLR/FU Berlin (G. Neukum)

With a difference. On Mars, where the average temperature is -70 F but can drop as low as -225 F at the poles, snowflakes are made of dry ice, conjuring up visions of astronauts shoveling their way out of a CO2 blizzard. As the planet warms during its summer seasons, most of the frost / snow vaporizes in the sunshine and the polar caps shrink back to their norms. While the seasonal covering is primarily carbon dioxide ice, both polar caps are primarily made of good, old-fashioned water ice.

A dust storm rages near the edge of Mars north polar region on May 24, 2002. Credit: NASA

The red tint you see in the Mars Express photo shows that each layer is far from pure ice but lined with dust. Every spring, solar heating vaporizes dry ice from the pole, stoking winds that whip up dust storms. Some storms are regional; others expand to enshroud the entire planet. Later in fall, as temperatures drop, those dust particles act as condensation nuclei or particles that coax chilled carbon dioxide to condense as snowflakes. Voila! Tinted snow.

Stacked like pancakes. Close up from orbit of layered ice and dust deposits at one of the Martian poles. Credit: NASA

Variations in Mars’ climate over millions of years changes the amounts of ice and dust deposited at the poles creating the beautiful swirly layers of white and orange. Just as the study of annual tree rings tell us about past environmental conditions, planetary scientists look to the Martian poles as repositories of the planet’s climate history. Someday we’ll drill ice cores there like we do from Earth’s glaciers.

Melting ice cream? No, this is a recent view of Mars’ south polar region taken by the ESA’s Mars Express spacecraft. Dust-stained ice is everywhere. The spiral pattern might be due to prevailing winds. Click to enlarge. Credit: ESA

ALMA reveals an infant solar system in remarkable detail

This is the sharpest image ever taken by ALMA, even crisper than is routinely achieved in visible light with the Hubble Space Telescope. It shows the protoplanetary disk surrounding the young star HL Tauri. Credit: ALMA (ESO/NAOJ/NRAO)

When this popped up on my computer I just assumed it was an artist’s impression of how planets form. Wow, was I wrong! It’s the real deal –  the clearest view ever of planet-forming dust rings around another star, and it was made possible by the incredible resolving power of the Atacama Large Millimeter Array (ALMA).

The Atacama Large Millimeter / submillimeter array showing the many radio dishes that are used in concert to create a much larger telescope able to resolve details in distant star-forming clouds. The array is located in the northern Chilean desert. Credit: Christoph Malin / ESO

Located in the Atacama Desert of northern Chile, the “telescope” is an array 66 39-foot (12-m) and 23-foot (7-m) diameter radio telescopes observing at millimeter and submillimeter wavelengths. Millimeter-sized waves are a form of light just like what we use to see the world around us only longer. They’re similar in size to the microwaves that cook your food; you’ll find them just beyond the infrared region of the spectrum.

The bullseye at the center of the rings is HL Tauri, a young star located 456 light years away in the Taurus Molecular Cloud, an enormous complex of dark clouds composed of gas and fine dust in the constellation Taurus. Stars form within the clouds as denser regions collapse under the force of gravity to form hot, compact, spinning cores. Most of the mass is concentrated in the center, where the material metamorphoses over millions of years into a brand new star as surely as a monarch caterpillar emerges from its chrysalis as a butterfly.

The protoplanetary disc surrounding the young star HL Tauri shows dark gaps where new planets may be taking shape.  In visible light, HL Tauri is hidden behind a massive envelope of dust and gas. ALMA observes at much longer wavelengths, which allows it to study the processes right at the core of this cloud. Credit: ALMA (ESO/NAOJ/NRAO)

Planets coalescing from the leftover dust surrounding the nascent star carve out a series of concentric rings. Whatever the shape of the original knot of gas and dust, collapse of the cloud causes it to flatten into a pancake called a protoplanetary disk. What’s incredible about the image is that it appears to show substructures within the disk pointing to possible positions of planets hatching in the dark patches within the system.

“These features are almost certainly the result of young planet-like bodies that are being formed in the disc. This is surprising since such young stars are not expected to have large planetary bodies capable of producing the structures we see in this image,” said Stuartt Corder, ALMA Deputy Director.

This image compares the size of the solar system with HL Tauri and its surrounding protoplanetary disc. Although the star is much smaller than the Sun, the disc around HL Tauri stretches out to almost three times as far from the star as Neptune is from the Sun. Credit: ALMA (ESO/NAOJ/NRAO)

HL Tauri is only about a million years old – compare that to the Sun and our well-heeled solar system which recently celebrated its 4.6 billionth birthday. Astronomers were a bit surprised to see planets already forming around such a young star. Looking at this image feels like stepping into a time machine and toggling back to see the Sun and planets when they were only babies. Mere dust and rocks struggling to reach planethood.

All the time, all the work, the amazing fact that it happens at all. And yet here we are as proof of remarkable things that happen when dust meets dust.

Will the Full Frosty Moon give you the shivers?

The Full Moon returns to an eastern horizon near you tomorrow evening. Click to find your moonrise time. Credit: Bob King

November’s the last month that still carries a connection to fall. Once December arrives, there’s no going back. Tomorrow at 4:23 p.m. (CST) the Full Beaver or Frosty Moon will rise near sunset and stay up all night.

This month we notice how much higher the Full Moon is than during the summer months. Why is that? Think where the Sun is right now. Have you noticed how much lower in the sky it is compared to June and July?  As our star hunkers down to its winter lair in Sagittarius, the Full Moon, directly opposite the Sun in the sky, moves into Taurus and Gemini. These are the very constellations the Sun occupies during the summer months when it blazes nearly overhead and cooks skin red if we’re not careful.

The Full Moon rises in the northeastern sky near the border of the constellations Cetus and Taurus. Taurus is one of the zodiac constellations and features the famous Pleiades star cluster about a fist to the right of the Moon. Stellarium

You needn’t worry about a moonburn. Although the Moon shines by reflected sunlight, it’s a dusty mirror covered in cobwebs. For all it takes in, our satellite delivers only 12% of the light back. Brilliant to the eye, it’s more than 165,000 times fainter than sunny Sol.

But as the Sun abandons us, Luna comes to the rescue. Despite its wimpy reflectivity, it’s the brightest object in the night sky. Once we allow our eyes to adapt to the dark, the Full Moon provides more than enough light to see our way around, pick out details of the landscape and even sense color. This is especially true now through early spring when the Moon climbs high in the sky where absorption of light by our atmosphere is least.

Clear November nights usually mean frost as the dew point drops below freezing. Don’t be surprised to see tomorrow night’s Full Moon illuminating your lawn as if it were a plush white carpet. Illustration: Bob King

From the countryside I’ve distinguished green leaves, the red of stop signs and other colors though they’re muted and occasionally take some convincing.

The quality of moonlight fascinates. Shadows are summertime short but black and stark. Contrasts are accentuated. A patch of dark behind a rock becomes a lurking animal. There’s just enough light to get around but not enough to provide the information we need to contain our imaginations. But hey, that’s half the fun.

Light passing through the eye’s lens and adjustable iris stimulates rod and cone cells the retina allowing us to see both at day and night.

Our retinas are equipped with two types of cells that respond to light — cones and rods. Cone cells, which are concentrated in the center of our visual field, are very good at color vision and detecting fine detail but only work well in bright light.

Rods are very sensitive to low light but not sensitive to color. We use them for night vision, peripheral vision and detecting fine motion. Because our “high-def” cone cells aren’t active in low light, the rod cells take over. While they’re great in moonlight, our vision lacks the kind of definition provided by the cones. Everything looks grainy at night like pictures shot at high ISO.

Like the other animals with whom we share the planet, we’re creatures of Earth’s day-night cycle; our vision has evolved to accommodate both brilliant sunlight and the tepid light of night.