What’s that musket ball doing on Mars?

Certainly catches the eye, doesn’t it? The spherical rock was photographed on September 11, 2014 by the Curiosity rover. It’s about a half-inch across and according to NASA scientists probably a concretion. Credit: NASA/JPL-Caltech/MSSS

It looks ever so much like an early 18th century musket ball, but the chances of soldiers traipsing around Mars a couple hundred years ago seems unlikely. Even if it’s the god of war. NASA’s Curiosity rover snapped this photo during a routine round of landscape imaging on September 11th.

There’s nothing like seeing a near-perfect sphere on another planet to make you sit up and wonder. First off, it’s not as big as you might think, measuring just under 1/2 (1 cm) in diameter or about the size of a marble. Second, we’ve seen spheres on Mars before – zillions of them!

Tiny “blueberries” in the Martian soil near the rock outcrop at Meridiani Planum called Stone Mountain. While other ideas have been proposed for their formation, water trickling through rocks to build concretions remains a strong possibility. Credit: NASA/JPL

The Mars Opportunity rover found countless spheres, nicknamed Martian “blueberries”, during  its exploration of Meridiani Planum. If you could hunker down for a look, they’d remind you of BBs from a  BB gun with diameters of .16 to .24 inches (4-6 mm). The spheres contain large amounts of hematite, an iron-bearing mineral, that most likely originated as concretions in layers of sedimentary rock that have since eroded away.

Groundwater moving through porous rocks can dissolve iron-containing minerals which then precipitate out as small, compact spheres. Concretions on Earth, such as Moqui balls and Kansas Pop Rocks, are considerably larger than the Martian variety, but that may be due to the different environments of the two planets. 

So our mystery sphere is probably a larger-than-usual concretion, freed from its rock stratum by wind and perhaps water erosion and now served up on a plate for Curiosity’s and eyes.

To view more pictures of the weird sphere, click HERE and scroll down toward the bottom for the Mastcam color images.

Rosetta rides the night train, drops within 12.4 miles of comet

Four-image mosaic of Comet 67P/C-G using images taken on September 24, 2014. Boulders 15-20 feet across are seen on the comet’s smooth, “neck” region. The partially-shadowed depression with a sharply defined rim at far left center spans about 1,150 feet (350 m) across. Click to enlarge. Credits: ESA/Rosetta/NAVCAM

For the past couple weeks Rosetta has been orbiting Comet 67P Churyumov-Gerasimenko from a distance of 18.6 miles (30 km) and returning crisp, detailed images like the one above using only its navigation camera. Tomorrow the spacecraft will drop even lower to 12.4 miles (20 km) as it alters its orbit for a look at the comet’s nightside.

By firing its thrusters, Rosetta can change its orbit about the comet to study and photograph features in morning and afternoon light during the current global mapping phase of the mission. Tomorrow, a new phase begins as Rosetta drops down to within 12.4 miles (20 km) of  the comet’s surface while passing over its night side. In mid-October (right) its orbit will be changed again to fly just 6.2 miles above 67P/C-G. Credit: ESA

Through a series of thruster firings, Rosetta has been changing the angle of its orbit above the comet’s day-night terminator to capture views of areas during their “morning hours” and later during local afternoon.

Maneuvers began on September 24th to direct the probe around the comet’s backside to study the temperature properties of the shadowed regions at the same time lowering its orbit to 12.4 miles (20 km). The spacecraft itself will remain in sunlight – like the space station crossing the sky at night – but the “ground” below will be in darkness. Rosetta has been descending since Wednesday and will reach the 12.4 mile mark as its orbit is “circularized”tomorrow, September 29. After a week at 12.4 miles, a decision will be made as to whether it’s safe to proceed to just 6.2 miles (10 km).

Rosetta navigation camera photo taken on September 21, 2014. The crater just right of center is the same one in shadow in the first photo. Its smooth walls contrast with the rubble-filled floor. A smaller, perhaps fresher dimple-like depression is labeled at right. Click to enlarge. Credit: ESA/Rosetta/NAVCAM

Assuming Rosetta continues to take photos during its nightside excursion, we should soon have much better pictures of the jets of vapor and dust it’s been geysering into space. Up till now, the craft has only photographed the comet with the sun at its back, a perspective that makes for brilliant images of the 2.5-mile-wide nucleus. The much fainter jets, made of fine particles, barely show. But seen from behind with the nucleus blocking the sun, the jets should really pop.

Close up of the 65-foot-wide “dimple” with a smoother rim than many of the other depressions. Because it lies atop a deposit, it’s probably a younger feature on the comet. Credit: ESA/Rosetta/NAVCAM

The same principle’s at work when you can see your breath on a cold winter day – the cloud of vapor (condensing water) is far brighter with the sun shining behind it than coming over your shoulder.

Looking more closely at the photos, we see lots of depressions. Most of them likely formed through surface collapse as buried ice vaporized in the solar heat or when gas trapped beneath the surface was expelled, leaving the crust unsupported.

There may also be impact craters too, though that scenario’s less likely given that any older impacts, like those seen on just about every planet and moon in the solar system, would have been erased from comet activity over the aeons.

Planets, moon gather at dusk / Curiosity chews into Mt. Sharp

The crescent moon and Saturn twist the night away this evening September 27, 2014. Catch the pair low in the southwestern sky 1-2 hours after sunset. Further east, Mars joins Antares in conjunction. Stellarium

Space weather experts are forecasting a minor G1 geomagnetic storm with possible auroras across the northern U.S. and southern Canada this evening.

While you’re out watching for that telltale green arc in the north, take a few minutes to face the opposite direction. Low above the southwestern horizon you’ll find the crescent moon parked near the planet Saturn. It may be our last chance to see the planet with ease. Saturn’s been sinking into the west for some time. Tonight’s moon will guide you right to it.

A little more than a fist to the left or east of Saturn, Mars will be in conjunction with its colorful friend Antares (both are red-hued) only 3.1º to its north. Both star and planet shine at magnitude +1 though Mars is officially a hair brighter. Can you see the difference?

Photo from the Mars Hand Lens Imager (MAHLI) camera on Curiosity shows the first sample-collection hole drilled in Mount Sharp, the layered mountain that is the science destination of the rover’s extended mission. The hole is 0.63 inch wide and about 2.6 inches deep and photographed from 2 inches away. Click to enlarge. Credit: NASA/JPL-Caltech

This week NASA’s Mars Curiosity Rover drilled and gathered its first rock sample from the base of Mt. Sharp in Gale Crater. The target rock formation, called Confidence Hills, lies on the Pahrump Hills outcrop at the base of the mountain. The rock is a mudstone and softer than any of the rocks previously sampled by the rover.

Mudstone rock outcrop where Curiosity got its first taste of Mt. Sharp (drill hole at top), the rover’s main science target during its time on Mars. Curiosity landed on the planet in August 2012. Credit: NASA/ JPL-Caltech, colorized by Bob King

“This drilling target is at the lowest part of the base layer of the mountain, and from here we plan to examine the higher, younger layers exposed in the nearby hills,” said Curiosity Deputy Project Scientist Ashwin Vasavada of JPL. Scientists hope to get a look at the first rock to underlie Mount Sharp to get a picture of the environment at the time the mountain formed and what led to its formation. Mount Sharp is composed of layered sediments, some of which appear to have been deposited by water several billion years ago.

Fish-eye view taken with Curiosity’s front hazcam showing the drill at work on the Confidence Hills target at the base of Mount Sharp September 24, 2014. The rock surface is webbed with cracks. Click to enlarge. Credit: NASA/JPL-Caltech, colorized by Bob King

NASA will put the breaks on Curiosity now that it’s reached its prime science destination after traveling 5 miles (8 km) since touching down on Mars August 6, 2012. Next, the rover will deliver a powdered rock sample into a scoop on it arm, where the soil’s texture will be scrutinized to access whether it’s safe for further sieving, portioning and delivery into Curiosity’s internal laboratory instruments without clogging hardware.

 

Coronal holes spark auroras Sept. 26-27 — more possible next 2 nights

The aurora around 1 a.m. CDT this morning. Curious forms twisted away in the northern sky in the Big Dipper. Details: 20mm lens, f/2.8, ISO 1600, 20-second exposure. Credit: Bob King

I apologize for not sending an alert earlier, but I was away from the computer and out under the sky tonight. Streams of solar wind from openings in the sun’s magnetic canopy called coronal holes kicked up auroras overnight for the northern states and Canada.

At 9:15 p.m. Friday night the aurora laid low in the northern sky. The arc is the curved border of the auroral oval that’s centered on Earth’s geomagnetic pole. Credit: Bob King

The display began and remained a very low arc from end of twilight until around 11 p.m. CDT when it slowly widened and brightened. The Kp index reached “4″ at that time, not quite a G1 geomagnetic storm but certainly pushing the threshold. Then at 12:20 the arc became brighter and more distinct and split into an exquisite set of short, parallel rays like keys on a piano. Faint rays reached halfway to the zenith as patches of aurora flashed on and off below.

Nice long rays stretch over the forest near Duluth, Minnesota U.S. early this Saturday morning September 27, 2014. Credit: Bob King

While modest, the display was active with a steady supply of rays and pulsating patches, but it never expanded beyond the northern half of the northern sky. Coronal hole effects will linger the next two nights, so be on alert for auroras to appear again.

MOM sends first pictures from Mars, says ‘the view is nice’

Tweet from India’s Mars Orbiter upon its safe entry into orbit around Mars September 24, 2014. Credit: ISRO

For less than it cost to make the movie “Gravity”, India built and flew a probe to Mars. AND they did it on their first attempt to reach the planet. About half of all probes sent to Mars have either crashed or gone off course. The planet’s known for its bad mojo.

India’s maiden Mars Orbiter Mission (MOM) to the Red Planet achieved orbit Wednesday, making it only the fourth country to successfully reach the Red Planet. The U.S., Europe and former Soviet Union have all sent probes to the planet beginning in the early 1960s.

MOM (Mars Orbiter Mission) now joins one European and three U.S. orbiters in a globe-encircling net of unblinking eyes on the Martian landscape and atmosphere below. You’ll recall the NASA’s MAVEN atmospheric probe only arrived last Sunday. It’s still in the checkout and orbit-shaping phase. In a few weeks, MAVEN will begin “tasting” the Martian air looking for clues of the planet’s missing water and thicker atmosphere it once possessed in abundance more than 3 billion years ago.

MOM tweeted this view of the surface of Mars today, adding “The view up here is nice.” Click to check out the probe’s light-hearted Twitter feed. Credit: ISRO

India’s total mission cost came to $74 million dollars, some $26 million less than the estimated price to film “Gravity”. MAVEN came in at $671 million, nearly 10 times as much.

Despite the Indian Space Research Organization’s frugality, critics in the home country have complained that the money could be better spent on feeding the poor and other projects. At the same time, the Indian people must feel justly proud today for this amazing accomplishment.

Indeed, that’s part of the mission’s purpose – to demonstrate that the county has developed technological prowess in the field of space exploration. All the instruments on board were built in India, including the cameras to photograph and map the surface, sensors to detect methane (an organic compound found in small quantities on Mars that may or may not be connected to potential microbes) and spectrometers to map minerals on the surface.

Photo of the planet and its dusty orange-brown atmosphere. Says MOM: ” I’m getting better at it. No pressure.” Gosh, the spacecraft even cracks jokes! Credit: ISRO

The Mars Orbiter Mission, also known informally as Mangalyaan after the Sanskrit words “Mangala” for Mars and “yana” for craft. MOM will orbit and study Mars for about six months until it runs out of fuel it needs to maintain orbit.

The folks behind the Twitter feed for MOM post updates with a light touch as you can tell from the probe’s first-person conversational style. This people-friendly approach is a great way to involve everyone in the mission. NASA does it too. Matter of fact, when MOM entered orbit, Curiosity tweeted: “Namaste! (Hindi for “greetings) Congratulations to @ISRO and India’s first interplanetary mission upon achieving Mars orbit.”

Night of the four fireballs – Eastern U.S. sees spectacle

Maps showing where the four separate fireballs were seen overnight last night September 24-25, 2014. Fireballs are defined as meteors equal to or brighter than magnitude -3 or between Jupiter and Venus in brightness. Credit: Mike Hankey / AMS

Four different fireball meteors lit up skies across the eastern U.S. last night according to reports received by the American Meteor Society (AMS). Normally, one brilliant fireball might zoom by every week or two, but last night four separate ones all came by within a few hours of each other. While brightness estimates vary a lot, nearly all the reports mention great brilliance and BIG. Many compared them to the full moon and some even to the sun in radiance! These were beauties.

Trajectories of the four fireballs over the eastern U.S. last night. Credit: Mike Hankey / AMS

Here’s a chronological list of their appearance. Times are eastern (EDT) and approximate:

* #1 at 9:30 p.m. over Tennessee, Kentucky Arkansas, Alabama, Mississippi, Missouri
* #2 at 9:47 p.m. over Connecticut, Massachusetts, Maryland, New Jersey, New York and Pennsylvania
* #3 at 10:13 p.m. over Illinois, Indiana, Wisconsin, Kentucky, Michigan, New York, Ohio, Ontario and Pennsylvania
* #4 at 1:09 a.m. over Florida and Georgia

Despite their brilliance, very few people reported hearing any associated sounds rumbles or explosions. This makes me think that none of the entering meteoroids made it to the ground. If you saw or heard anything at those times, the AMS would love to hear about it. Please enter your report HERE.

I have yet to find any video from security cameras and cellphone captures. If you have any visuals, please also report that on your AMS form. It would also be very helpful to send it to Dirk Ross who runs the Latest Worldwide Meteor/Meteorite News. As usual there are a few silly references to this being some kind of prophecy of doom. This happens every time something remarkable happens in the sky. Last time I looked, we were all still standing.

As to whether four fireballs is purely coincidence or if they might in some way be related (prior breakup before entering Earth’s atmosphere?) it’s very difficult to say. If you look at the trajectories, there are two pairs similar to one another. Hopefully we’ll learn more when video surfaces and more reports are made.

Check out the aurora! It’s on tonight Sept. 23-24

A fine aurora with many small rays spread across the northern sky around 10 p.m. CDT this evening September 23, 2014. Credit: Bob King

If the sky is clear and you live in the northern U.S. the northern lights are visible right now at 10-10:30 p.m. CDT. Not a huge display, but there’s a broad greenish arc/glow across the northern sky streaked with rays that reach up to the North Star. Very pretty.

A few bright rays below the Bowl and Handle of the Big Dipper at 10:15 p.m. Credit: Bob King

No telling how long it might last, but it’s been out at least since 9:30. No storms, not even minor ones, were in the forecast, but there you have it anyway. The Kp index is currently at “4″ just below minor storm level and the direction of the magnetic field bundled with the solar wind has been tipped south (a good direction for linking up with Earth’s field) for about the past 7 hours. Let’s hope it sticks around!

* Update Weds. September 24 – We’re right on the edge tonight with a chance for a minor display of aurora according to the most recent forecast.

Extent of the auroral oval around 10:30 p.m. CDT shows expansion to the south. Notice the view line brushes the northern states. Click to see current oval. Credit: NOAA

How long would it take to drive to the sun?

My old Subaru achieved lunar orbit when the odometer hit 238,000 miles several years back. Credit: Bob King

I spend way too much time in the car, mostly on the job as a photojournalist. Every day, there are places to be at this time and that. Like many who drive around for a living,  I’ve accumulated a few miles on my vehicles.

Once, in an older Subaru, I achieved a one-time dream of reaching the moon. The odometer rolled past the 238,000 mile mark – just under the average lunar distance but easily within perigee range. I would have pushed the vehicle further, but the brakes seized up and soon after I sold the car. I recall it leaving the driveway on a flatbed like a patient being wheeled away to the emergency room.

The sun is some 387 times farther from Earth than the moon. Credit: Bob King

The years of driving it took to “get to the moon” got me wondering how long it would take to drive to the sun, which lies some 93 million miles (150 million km) from Earth or 387 times farther away than the moon.  According to the Guinness Book of World Records, the record vehicle mileage goes to a 1966 Volvo P-1800S with more than  2,850,000 miles (4,586,630 km). Owned by Irvin Gordon of East Patchogue, New York, the car is still driven daily.

A commercial jet flying at 550 mph would need 19 years to reach the sun. Credit: Bob King

While that trashes my record, it’s still only 3% of the way to the sun, a nice start but barely there. Instead, let’s drive non-stop at 60 mph (97 kph). How long would it take before we would complete our journey? An amazingly long time – 177 years. Strange, isn’t it? The sun seems so close because we can feel its warmth and watch it ripen our tomatoes. But it’s out there, w-a-y out there.

Even in a commercial jet flying at 550 mph (885 kph) it would still take 19 years. I’m afraid I just don’t have that kind of time or patience. Even the 5-hour trip to Hawaii from Los Angeles made me twitchy. The Helios probes, the fastest moving space vehicles ever, reached speeds of 157,000 mph as they orbited around the sun sensing the solar wind. At that rate, the sun could be reached in just 24.7 days.


Bill Nye demonstrates the distances between the planets.

How about a planet? Let’s choose picturesque Saturn, now low in the southwestern sky at dusk. Its average distance from the sun is 891 million miles (1.4 billion km) or 1,695 years in a car. That means if we started driving in 320 A.D. when ancient Rome still dominated the western world, we’d finally arrive today. Aw heck, I’d rather take a plane and get there in just 185 years.

Maps showing the planets and layout of the solar system give a false impression of sizes and distances. But you can hardly blame the creators. There’s just too much empty space between the planets compared to their tiny sizes to squeeze it all a useful diagram. Credit: NASA

Even in the solar system, never mind the stars, distances are so immense we can hardly comprehend them. If we reduced the sun to the size of a grapefruit, Earth would be a poppy seed 35 feet (10.7 m) away, Saturn a pea at 335 feet (102 m) and the nearest star system, Alpha Centauri, a pair of grapefruits 1,800 miles (2,900 km) away. There’s so much emptiness and so little stuff, it’s mind-boggling.

Frosty and fresh, fall begins tonight

Frost on colorful leaves, a sure sign that fall has arrived. Credit: Bob King

Lots of us have looked forward to the first day of fall after summer’s heat and humidity. I like the feel of a sweater on a night’s walk and the fire-hued trees that provide a pleasant distraction while sitting in traffic.

Two views of the sun’s travels along the celestial equator on the first day of fall. The left side shows the view from the equator where the sun passes overhead. The right shows the view from 50 degrees north latitude (S. Canada, Europe). At the north pole, the sun would follow a path along the horizon. Credit: Tau’olunga

The new season begins quietly tonight at 9:29 p.m. Central time. At that moment the sun drops into the southern sky like a penny in a piggy bank and fall officially begins. At the fall and spring equinoxes, the sun crosses the celestial equator, an imaginary extension of Earth’s equator into the sky. Picture the celestial equator as half of an imaginary hula hoop tilting up from the eastern horizon, crossing the southern sky and then arcing back down to the western horizon. The hoop’s other half continues below the horizon and beneath our feet, circling over the opposite hemisphere.

On the first day of autumn, the sun crosses the celestial equator moving south. The sun’s apparent motion across the sky over the year is caused by Earth’s revolution around the sun. Illustration: Bob King

If you live in parts of Kenya, Ecuador or Indonesia the celestial equator passes directly overhead. On the first day of spring and fall, it’s directly overhead at noon.

In mid-northern latitudes it cuts midway across the southern sky. On the first day of spring, the sun crosses this celestial borderline moving north. Seen from the northern hemisphere, the sun’s northward movement brings it higher and higher in the sky. Days lengthen and nights get shorter as we transition from spring to summer.

Tonight, the sun crosses the equator moving south along its yearly circuit of the sky. The southward-moving sun slides lower and lower in the coming days and weeks. We’ll watch daylight diminish at the expense of night as the northern hemisphere makes its transition from fall to winter.


Video to help picture Earth’s orbit around the sun and how its tilted axis causes different parts of the planet to receive different amounts of sunlight during the year. Variation in the amounts of daylight vs. night gives us the four seasons.

Seasons are caused by the 23.5 degree tilt of our planet’s axis. As Earth moves along its yearly orbit, the north-south position of the sun changes because of the changing orientation of our axis. When the north polar axis is pointed toward the sun, our star reaches its most northerly point in the sky and we experience long days and summer heat.

The first day of fall is special because Earth’s axis points neither toward nor away from the sun. Instead, we’re broadside to our star, and day and night are approximately equal across the planet.

The word equinox comes comes from the Latin words for equal and night because both day and night are approximately 12 hours long. Prior to September 22, days are longer; after the 22nd they get shorter. Shorter days are caused by the sun dropping farther south in the sky (lower altitude). The lower the sun, the less time it spends crossing the sky and the shorter the hours of daylight.

The sun in this sunrise photo is an illusion caused by the thick air at the horizon bending the real sun (still below the horizon) into view. Credit: Lyle Anderson; illustration: NOAA

Notice I didn’t say that day and night are exactly equal at the equinoxes. While it’s true that the center of the sun sets exactly 12 hours after it rises on the first day of fall, we determine sunrise at the first sighting of the sun, when its upper edge (not center) breaches the horizon. Similarly, sunset occurs when the last bit of sun disappears below the horizon. That adds about two minutes of extra daylight to the day.

We get another few minutes thanks to atmospheric refraction. That’s our atmosphere’s freaky ability to act like a prism and bend the sun’s rays upward into view when it’s still below the horizon. If you ever have the chance to see the sun directly on the horizon at sunset or sunrise, you’ll witness one of nature’s grandest illusions. The sun’s not really there. The air is thick enough across your sight line to “lift” the sun into view about two minutes before it rises for real.

MAVEN makes it safely to Mars!

This image shows an artist concept of NASA’s Mars Atmosphere and Volatile Evolution (MAVEN) mission. Credit: NASA/Goddard Space Flight Center

After 10 months and over 422 million miles (771 million km) of travel, NASA’s Mars Atmosphere Volatile EvolutioN spacecraft settled safely into orbit around Mars Sunday evening at 9:24 p.m. Central Daylight Time. Engineers and scientists waited tensely as the onboard computers fired thrusters for 33 minutes to slow the craft enough so it could be captured by Mars’ gravity. The operation went smoothly.

MAVEN joins a fleet of other craft working at the Red Planet including Mars Odyssey, Mars Express and Mars Reconnaissance Orbiter and the two rovers, Opportunity and Curiosity. On Wednesday, India’s Mars Orbiter Mission (MOM) will join the clan as it too brakes to settle into orbit.

“This was a very big day for MAVEN,” said David Mitchell, MAVEN project manager from NASA’s Goddard Space Flight Center, Greenbelt, Maryland. “We’re very excited to join the constellation of spacecraft in orbit at Mars and on the surface of the Red Planet. The commissioning phase (when the instruments will be checked and orbit slimmed from 35 to 4.5 hours) will keep the operations team busy for the next six weeks, and then we’ll begin, at last, the science phase of the mission. Congratulations to the team for a job well done today.”

Mars was once a much wetter and warmer planet (left) than it is today. Because it’s not protected by a planet-wide magnetic field like Earth, it’s thought that the sun and solar wind stripped away its atmosphere over time, leading to a cold, dry desert world (right). Credit: NASA

MAVEN’s primary mission will last one Earth year taking measurements of the composition, structure and escape of gases in Mars’ upper atmosphere and its interaction with the sun and solar wind. Without protection from a planet-wide magnetic field, it’s thought that the sun and solar wind have stripped molecules from the Martian atmosphere over time. MAVEN will dip into Mars’ atmosphere only 93 miles (150 km) above the surface to study how and what kinds of atoms are disappearing. Several deeper-dip missions will bring it to within 78 miles (125 km) altitude.

For more on MAVEN, check out the MAVEN website and this article in Universe Today.