Why Is Comet ISON Green?

Recent images of Comet ISON along with spectral data. Credit and copyright: Chris Schur.

Undoubtedly, you’ve been seeing the recent images of Comet ISON now that it is approaching its close encounter with the Sun on November 28. ISON is currently visible to space telescopes like the Hubble and amateur astronomers with larger telescopes. But you might be wondering why many images show the comet with a green-ish “teal” or blue-green color.

Amateur Astronomer Chris Schur has put together this great graphic which provides information on the spectra of what elements are present in the comet’s coma.

For the conspiracy theorists out there, the green color is actually a good omen, and lots of comets display this color. The green color is a sign the comet is getting more active as gets closer to the Sun – meaning it is now putting on a good show for astronomers, and if it can continue to hold itself together, it might become one of the brightest comets in the past several years.

“ISON’s green color comes from the gases surrounding its icy nucleus,” says SpaceWeather.com’s Tony Phillips. “Jets spewing from the comet’s core probably contain cyanogen (CN: a poisonous gas found in many comets) and diatomic carbon (C2). Both substances glow green when illuminated by sunlight in the near-vacuum of space.”

Comet ISON on October 4, 2013 as seen over Arizona, viewed with a 12.5" telescope, over an hour exposure time. Credit and copyright: Chris Schur.
Comet ISON on October 4, 2013 as seen over Arizona, viewed with a 12.5″ telescope, over an hour exposure time. Credit and copyright: Chris Schur.

Both are normally colorless gases that fluoresce a green color when excited by energetic ultraviolet light in sunlight.

And if those poisonous gasses sound dangerous, don’t worry. They are spread out in space much too thinly to touch us here on Earth. So don’t fall prey to fear mongers who are out to bilk the masses – like people did in 1910 when Comet Halley made a return to the skies and swindlers pitched their ‘gas masks’ and special ‘comet pills’ for protection. And of course, nothing happened.

But back to the color. Chris Schur provided this info along with his graphic:

Your readers may appreciate knowing why comets can appear this color. The background image is the shot I took with my 12.5″ and an ST10xme CCD camera for 20 minutes in mid-October. A pale coloration of the front of the coma is seen. To the lower left is a shot with the same instrument but with a 100 lpmm (line pair per millimeter) diffraction grating in front of the CCD chip to break out the spectra of the objects in the entire field.

Here ISON is faintly seen to the left of center, and the first order spectra a band to its right. But the real answer comes when we use the software called Rspec to analyze this band of light. The result is on the lower right. Normally reflected sunlight is rather flat and bland, and mostly that is what ISON is right now, reflected from dust. But labeled are two humps in the blue and green parts of the spectrum labeled “C2” for a carbon molecule. This blue/green emission pair is what gives ISON the color.

Chris notes that as the comet nears the Sun, astronomers and astrophotographers will be able to resolve more spectral details in the comet. “It will be exciting to watch the changes as more molecules pop out,” Chris said via email, “and possibly when it is closest to the Sun, we just may see some metal lines like iron or magnesium from MELTED vaporized rock. How exciting!”

And for those who insist there is something nefarious about Comet ISON, take a look at this FAQ from our friend Stuart Atkinson, who hosts the great site Waiting for ISON. He addresses the many conspiracy theories that are out there regarding this comet.

ISON FAQ Sept 9 jpg

‘Light Echos’ Reveal Old, Bright Outbursts Near Milky Way’s Black Hole

X-ray emissions from the supermassive black hole in the center of the Milky Way galazy, about 26,000 light years from Earth. Credit: NASA/CXC/APC/Université Paris Diderot/M.Clavel et al

How’s that for a beacon? NASA’s Chandra X-ray Observatory has tracked down evidence of at least a couple of past luminous outbursts near the Milky Way’s huge black hole. These flare-ups took place sometime in the past few hundred years, which is very recently in astronomical terms.

“The echoes from Sagittarius A were likely produced when large clumps of material, possibly from a disrupted star or planet, fell into the black hole,” the Chandra website stated.

“Some of the X-rays produced by these episodes then bounced off gas clouds about 30 to 100 light years away from the black hole, similar to how the sound from a person’s voice can bounce off canyon walls. Just as echoes of sound reverberate long after the original noise was created, so too do light echoes in space replay the original event.”

The astronomers saw evidence of “rapid variations” in how X-rays are emitted from gas clouds circling the hole, revealing clues that the area likely got a million times brighter at times.

Check out more information on Chandra’s website.

Japanese ‘Space Cannon’ On Track For Aiming At An Asteroid: Reports

Painting of Asteroid 2012 DA14. © David A. Hardy/www.astroart.org

Watch out, asteroid 1999 JU3: you’re being targeted. As several media reports reminded us, the Japan Aerospace Exploration Agency (JAXA)’s Hayabusa-2 asteroid exploration mission will carry a ‘space cannon’ on board — media-speak for the “collision device” that will create an artificial crater on the asteroid’s surface.

“An artificial crater that can be created by the device is expected to be a small one with a few meters in diameter, but still, by acquiring samples from the surface that is exposed by a collision, we can get fresh samples that are less weathered by the space environment or heat,” JAXA states on its website.

Reports indicate JAXA is on schedule to, er, shoot this thing into space for a 2018 rendezvous with an asteroid. The spacecraft will stick around the asteroid for about a year before heading back to Earth in 2020. The overall aim is to learn more about the origin of the solar system by looking at a C-type asteroid, considered to be a “primordial body” that gives us clues as to the early solar system’s makeup.

Check out more on Hayabusa-2 on JAXA’s website.

Beautiful Comet ISON Timelapse and Recent Images

Comet ISON, as seen on October 21, 2013 from Marion, Ohio, USA, using a QHY9 monochrome CCD camera and TEC 140 F7, 5 inch Refractor telescope. Credit and copyright: Cliff Spohn and Terry Hancock.

This beautiful new view of Comet ISON comes from a collaborative effort between astrophotographers Cliff Spohn in Ohio and Terry Hancock in Michigan, taken on October 21, 2013. “The first time in almost two weeks that we have had a break in the clouds and rain we could not miss this rare opportunity to capture ISON using Cliff’s equipment,” said Terry via email. “Credit goes to Cliff for capturing the object while I did the calibration, stacking in CCDStack post processing in CS5 and video editing.”

You can see a timelapse video below, covering 93 minutes of imaging, again on October 21. It’s obvious ISON is still intact and it continues to bright, as it is currently about magnitude 9.

More recent images:

Update: This new one is just in from astrophotographer Damian Peach, and its a beauty! Taken on October 24.

Comet C/2012 S1 ISON captured passing fairly close to the bright barred spiral galaxy M95 in Leo on October 24, 2013. Credit and copyright: Damian Peach.
Comet C/2012 S1 ISON captured passing fairly close to the bright barred spiral galaxy M95 in Leo on October 24, 2013. Credit and copyright: Damian Peach.
Comet ISON C/2012 S1, Mars, & Regulus on 10-18-2013 Warrenton, Virginia 6:27am EST Canon Rebel Xsi & 170mm lens F6.3, ISO 400, 6 minutes 6 secs. Credit and Copyright: John Chumack.
Comet ISON C/2012 S1, Mars, & Regulus on 10-18-2013
Warrenton, Virginia 6:27am EST
Canon Rebel Xsi & 170mm lens F6.3, ISO 400,
6 minutes 6 secs. Credit and Copyright: John Chumack.

From John Chumack: “I just had to try just a telephoto on Comet ISON while it was near Mars,” John said via email. This view shows Comet ISON (C/2012 S1) near Mars and Regulus, the brightest star in the constellation Leo. This image was taken on October 18, 2013 from
Warrenton, Virginia at 6:27am EST looking over Washington D.C.

Triple conjunction of Comet ISON, Mars, Regulus on October 14, 2013, as seen from Payson, Arizona, USA. Credit and copyright: Chris Schur.
Triple conjunction of Comet ISON, Mars, Regulus on October 14, 2013, as seen from Payson, Arizona, USA. Credit and copyright: Chris Schur.

This nice image comes from Chris Schur from Arizona, taken on October 14, and is also of the conjunction. “As you may recall, on this date of 10/14 the three objects were in a perfect line going from south to north in Leo,” Chris said via email. “What a spectacular sight in the 11 x 80 binoculars! While the comet was quite faint, a short 1/4 degree of tail could be seen, and the gorgeous blue and orange colors of the planets.”

Chris used a Canon Xti, ASA800 with 10 minutes total integration time, with a 80mm f/4.8 Ziess APO refractor on a Televue GEM. Taken from Payson, Arizona at 5,100 feet elevation.

Watch the Sun Split Apart

Canyon of Fire on the Sun, Credit: NASA/SDO/AIA)

Here’s your amazing oh-my-gosh-space-is-so-cool video of the day — a “canyon of fire” forming on the Sun after the liftoff and detachment of an enormous filament on September 29-30. A new video, created from images captured by the Solar Dynamics Observatory (SDO) and assembled by NASA’s Goddard Space Flight Center, shows the entire dramatic event unfolding in all its mesmerizing magnetic glory.

Watch it below:

Solarrific! (And I highly suggest full-screening it in HD.) That filament was 200,000 miles long, and the rift that formed afterwards was well over a dozen Earths wide!

Captured in various wavelengths of light by SDO’s Atmospheric Imaging Assembly (AIA) the video shows the solar schism in different layers of the Sun’s corona, which varies greatly in temperature at different altitudes.

According to the description from Karen Fox at GSFC:

“The red images shown in the movie help highlight plasma at temperatures of 90,000° F and are good for observing filaments as they form and erupt. The yellow images, showing temperatures at 1,000,000° F, are useful for observing material coursing along the sun’s magnetic field lines, seen in the movie as an arcade of loops across the area of the eruption. The browner images at the beginning of the movie show material at temperatures of 1,800,000° F, and it is here where the canyon of fire imagery is most obvious.”

Now, there’s not really any “fire” on the Sun — that’s just an illustrative term. What we’re actually seeing here is plasma contained by powerful magnetic fields that constantly twist and churn across the Sun’s surface and well up from its interior. The Sun is boiling with magnetic fields, and when particularly large ones erupt from deep below its surface we get the features we see as sunspots, filaments, and prominences.

When those fields break, the plasma they contained gets blasted out into space as coronal mass ejections… and this is what typically happens when one hits Earth. (But it could be much worse.)

Hey, that’s what it’s like living with a star!

Stay up to date on the latest solar events on the SDO mission page here.

Video: Spider Flown in Space Has Trouble Readapting to Gravity

Nefertiti, the "Johnson Jumper" spider hunting for flies inside her habitat on board the International Space Station (ISS). (NASA)

Astronauts have said adapting to weightlessness is much easier than readapting to gravity when they returned to Earth. Muscle weakness, wobbly legs, and feeling like the room is spinning is common after long duration spaceflight, not to mention the long-term issues like bone loss, diminished eyesight, and a heart that has to recondition itself to pump blood harder to overcome gravity. As Canadian Chris Hadfield said, “My body was quite happy in space without gravity.”

It turns out spiders have similar issues. This Phiddipus Johnsoni, or red-backed jumping spider named Nefertiti is shown walking and preying on flies in her habitat while in orbit on the International Space Station and then doing the same while readapting to gravity on Earth. While trying to capture its prey, it ends up flopping awkwardly onto its back. No more flying like SuperSpider.

Nefertiti was in space 100 days in 2012 as part of a student-initiated science experiment of YouTube’s Space Lab, an online video contest. After returning home, this spidernaut was sent to the Smithsonian Institution’s National Museum of Natural History in Washington, D.C. and was part of exhibition of the first jumping spider to survive the trip to space. Unfortunately Nefertiti died just a few days after being sent to the museum.

Space Trucks! A Pictorial History Of These Mighty Machines

A view of Orbital Sciences' Cygnus spacecraft while it was being released from the International Space Station on Oct. 22. Credit: NASA/Karen Nyberg

Cargo resupply ships are vital for space exploration. These days they bring food, experiments and equipment to astronauts on the International Space Station. And in recent years, it hasn’t just been government agencies sending these things up; SpaceX’s Dragon spacecraft and (just this week) Orbital Sciences’ Cygnus spacecraft brought up cargo of their own to station in recent months.

NASA just published a brief timeline of (real-life) cargo spacecraft, so we thought we’d adapt that information in pictorial form. Here are some of the prominent members of that elite group. Did we miss anything? Let us know in the comments.

Dragon in orbit during the CRS-2 mission. Credit: NASA/CSA/Chris Hadfield
SpaceX’s Dragon in orbit during the CRS-2 mission. It was the first commercial spacecraft to resupply the space station, and since 2012 has completed resupply missions. Credit: NASA/CSA/Chris Hadfield
Thrust
Space shuttle Discovery heads to space after lifting off from Launch Pad 39A at NASA’s Kennedy Space Center in Florida to begin its final flight to the International Space Station on the STS-133 mission. The shuttle was NASA’s main human spacecraft between 1981 and 2011. Credit: NASA
Progress 51 on final approach to the International Space Station. The stuck antenna is visible below the crosshairs. Credit: NASA TV (screencap)
Progress 51 on final approach to the International Space Station. The Russians have been flying versions of this cargo spacecraft since 1978. Credit: NASA TV (screencap)
JAXA's H-II Transfer Vehicle during a mission in July 2012. The first demonstration flight took place in 2009. Credit: NASA
JAXA’s H-II Transfer Vehicle (HTV) during a mission in July 2012. The first demonstration flight took place in 2009. Credit: NASA

 

The ATV Johannes Kepler docked at the International Space Station. Credit: NASA
The ATV Johannes Kepler docked at the International Space Station. Versions of this spacecraft have flown since 2008. Credit: NASA
A line drawing of the TKS (Transportnyi Korabl’ Snabzheniia, or Transport Supply Spacecraft). It was intended to send crew and cargo together in one flight, but delays and a change in program priorities never allowed it to achieve that. According to NASA, versions of TKS (under the Cosmos designation) flew to the Salyut 6 and Salyut 7 space station. The cargo part of the spacecraft was also used for Russian base modules in the Mir space station and International Space Station. Credit: NASA/Wikimedia Commons
A line drawing of the TKS (Transportnyi Korabl’ Snabzheniia, or Transport Supply Spacecraft). It was intended to send crew and cargo together in one flight, but delays and a change in program priorities never allowed it to achieve that. According to NASA, versions of TKS (under the Cosmos designation) flew to the Salyut 6 and Salyut 7 space station. The cargo part of the spacecraft was also used for Russian base modules in the Mir space station and International Space Station. Credit: NASA/Wikimedia Commons

How Many Satellites are in Space?

How Many Satellites are in Space?

The space age began on October 4, 1957 with the launch of the first artificial satellite, Sputnik 1. This tiny spacecraft lasted only three months in orbit, finally burning up in the Earth’s atmosphere.

Following in these historic footsteps, many more spacecraft have been sent into Earth’s orbit, around the Moon, the Sun, the other planets, and even out of the Solar System itself. At the time that I’m recording this video, there are 1071 operational satellites in orbit around the Earth. 50 percent of which were launched by the United States.

Half of that 1071 are in Low-Earth Orbit, just a few hundred kilometers above the surface. Some of the most notable of these include the International Space Station, the Hubble Space Telescope, and many Earth observation satellites.

About a twentieth are in Medium-Earth Orbit, around 20,000 kilometers up, which are generally global positioning satellites used for navigation. A small handful are in elliptical orbits, where their orbit brings them closer and further to the Earth.
The rest are in geostationary orbit, at an altitude of almost 36,000 kilometers.

If we could see these satellites from Earth’s surface, they would appear to hang motionless in the sky. The fact that they remain over the geographic same area means they provide the perfect platform for telecommunications, broadcast or weather observations.

But there are many, many more artificial objects orbiting the Earth. In this collection of space debris we’re talking spent boosters, dead satellites, and even misplaced gloves. According to the United States Space Surveillance Network, there are more than 21,000 objects larger than 10 cm orbiting the Earth. Just a small fraction of these are operational satellites. It’s estimated there are a further 500,000 bits and pieces between 1 and 10 cm in size.

Near Earth orbit is so polluted with junk that the International Space Station is often moved to avoid impact with dangerous chunks of space debris. Many of these objects are created through collisions, and some scientists are worried that future space travel might be too risky if we get too much junk orbiting the planet. We might seal ourselves inside a shield of shrieking metal moving at 29,000 km/hour.

Looking outwards from our own orbit, at any time there are a handful of satellites orbiting the Moon. Right now, NASA’s Lunar Reconnaissance Orbiter and Lunar Atmosphere and Dust Environment Explorer are in lunar orbit. Further still, there’s 1 spacecraft around Mercury, 1 at Venus, 3 visiting Mars and 1 orbiting Saturn. There’s a handful of spacecraft orbiting the Sun, although they’re leading or trailing the Earth in its orbit. And a few spacecraft are on trajectories to take them out of the Solar System entirely. NASA’s Voyager spacecraft, exited the Sun’s heliosphere in 2013, and entered the interstellar medium.

Starting with Sputnik’s lonely journey over 50 years ago, It’s amazing to consider just how many satellites we’ve already launched into space in just a few decades. With more launches all the time, space is becoming a busy place, with so many exciting missions to look forward to.

We have written many articles about satellites for Universe Today. Here’s an article about two satellites that collided in Earth orbit, and here are some pictures of satellites.

You can learn more about the US Space Surveillance Network from the United States Strategic Command website.

We have also recorded a whole episode of Astronomy Cast about space junk. Listen here, Episode 82: Space Junk.

NASA’s Resilient Opportunity Rover Starts Martian Mountaineering

Opportunity starts Martian Mountaineering. NASA’s Opportunity rover captured this southward uphill panoramic mosaic on Oct. 21, 2013 (Sol 3463) after beginning to ascend the northwestern slope of "Solander Point" on the western rim of Endeavour Crater - her 1st mountain climbing adventure. The northward-facing slope will tilt the rover's solar panels toward the sun in the southern-hemisphere winter sky, providing an important energy advantage for continuing mobile operations through the upcoming winter. Assembled from Sol 3463 navcam raw images by Marco Di Lorenzo and Ken Kremer. Credit: NASA/JPL/Cornell/Marco Di Lorenzo/Ken Kremer

Opportunity starts Martian Mountaineering
NASA’s Opportunity rover captured this southward uphill panoramic mosaic on Oct. 21, 2013 (Sol 3463) after beginning to ascend the northwestern slope of “Solander Point” on the western rim of Endeavour Crater – her 1st mountain climbing adventure. The northward-facing slope will tilt the rover’s solar panels toward the sun in the southern-hemisphere winter sky, providing an important energy advantage for continuing mobile operations through the upcoming winter. Assembled from Sol 3463 navcam raw images by Marco Di Lorenzo and Ken Kremer.
Credit: NASA/JPL/Cornell/Marco Di Lorenzo/Ken Kremer
Story and imagery updated[/caption]

NASA’s super resilient Opportunity robot has begun a new phase in her life on the Red Planet – Martian Mountaineer!

“This is our first real Martian mountaineering with Opportunity,” said the principal investigator for the rover, Steve Squyres of Cornell University, Ithaca, N.Y.

And it happened right in the middle of the utterly chaotic US government shutdown ! – that seriously harmed some US science endeavors. And at a spot destined to become a science bonanza in the months and years ahead – so long as she stays alive to explore ever more new frontiers.

On Oct. 8, mission controllers on Earth directed the nearly decade old robot to start the ascent of Solander Point – the northern tip of the tallest hill she has encountered after nearly 10 Earth years on Mars.

Opportunity starts scaling Solander Point - her1st mountain climbing goal. See the tilted terrain and rover tracks in this mosaic view from Solander Point peering across the vast expanse of huge Endeavour Crater.  Opportunity will ascend the mountain looking for clues indicative of a Martian habitable environment.  This navcam camera mosaic was assembled from raw images taken on Sol 3431 (Sept.18, 2013).  Credit: NASA/JPL/Cornell/Marco Di Lorenzo/Ken Kremer (kenkremer.com). See the complete panoramic view below
Opportunity starts scaling Solander Point – her1st mountain climbing goal. See the tilted terrain and rover tracks in this mosaic view from Solander Point peering across the vast expanse of huge Endeavour Crater. Opportunity will ascend the mountain looking for clues indicative of a Martian habitable environment. This navcam camera mosaic was assembled from raw images taken on Sol 3431 (Sept.18, 2013). Credit: NASA/JPL/Cornell/Marco Di Lorenzo/Ken Kremer (kenkremer.com). See the complete panoramic view below

The northward-facing slopes at Solander also afford another major advantage. They will tilt the rover’s solar panels toward the sun in the southern-hemisphere winter sky, providing an important energy boost enabling continued mobile operations through the upcoming frigidly harsh winter- her 6th since landing in 2004.

Opportunity will first explore outcrops on the northwestern slopes of Solander Point in search of the chemical ingredients required to sustain life before gradually climbing further uphill to investigate intriguing deposits distributed amongst its stratographic layers.

The rover will initially focus on outcrops located in the lower 20 feet (6 meters) above the surrounding plains on slopes as steep as 15 to 20 degrees.

Opportunity starts scaling Solander Point - her 1st mountain climbing goal. See the tilted terrain and rover tracks in this panoramic view from Solander Point peering across the vast expanse of huge Endeavour Crater.  Opportunity will ascend the mountain looking for clues indicative of a Martian habitable environment.  This navcam camera mosaic was assembled from raw images taken on Sol 3431 (Sept.18, 2013).  Credit: NASA/JPL/Cornell/Marco Di Lorenzo/Ken Kremer (kenkremer.com).
Opportunity starts scaling Solander Point – her 1st mountain climbing goal. See the tilted terrain and rover tracks in this panoramic view from Solander Point peering across the vast expanse of huge Endeavour Crater. Opportunity will ascend the mountain looking for clues indicative of a Martian habitable environment. This navcam camera mosaic was assembled from raw images taken on Sol 3431 (Sept.18, 2013). Credit: NASA/JPL/Cornell/Marco Di Lorenzo/Ken Kremer (kenkremer.com).

At some later time, Opportunity may ascend Solander farther upward, which peaks about 130 feet (40 meters) above the crater plains.

“We expect we will reach some of the oldest rocks we have seen with this rover — a glimpse back into the ancient past of Mars,” says Squyres.

NASA’s powerful Mars Reconnaissance Orbiter (MRO) circling overhead recently succeeded in identifying clay-bearing rocks during new high resolution survey scans of Solander Point!

As I reported previously, the specially collected high resolution observations by the orbiters Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) were collected in August and being analyzed by the science team. They will be used to direct Opportunity to the most productive targets of interest

“CRISM data were collected,” Ray Arvidson told Universe Today. Arvidson is the mission’s deputy principal scientific investigator from Washington University in St. Louis, Mo.

“They show really interesting spectral features in the [Solander Point] rim materials.”

NASA’s Opportunity rover captured this southward uphill view on Oct. 21, 2013 after beginning to ascend the northwestern slope of "Solander Point" on the western rim of Endeavour Crater. The northward-facing slope will tilt the rover's solar panels toward the sun in the southern-hemisphere winter sky, providing an important energy advantage for continuing mobile operations through the upcoming winter.  Credit: NASA/JPL
NASA’s Opportunity rover captured this southward uphill view on Oct. 21, 2013 after beginning to ascend the northwestern slope of “Solander Point” on the western rim of Endeavour Crater. The northward-facing slope will tilt the rover’s solar panels toward the sun in the southern-hemisphere winter sky, providing an important energy advantage for continuing mobile operations through the upcoming winter. Credit: NASA/JPL

The new CRISM survey from Mars orbit yielded mineral maps which vastly improves the spectral resolution – from 18 meters per pixel down to 5 meters per pixel.

This past spring and summer, Opportunity drove several months from the Cape York rim segment to Solander Point.

“At Cape York, we found fantastic things,” Squyres said. “Gypsum veins, clay-rich terrain, the spherules we call newberries. We know there are even larger exposures of clay-rich materials where we’re headed. They might look like what we found at Cape York or they might be completely different.”

The summit of Solander Point.  Opportunity rover captured mosaic on Oct. 21, 2013 (Sol 3463) after beginning to ascend the northwestern slope of "Solander Point" on the western rim of Endeavour Crater - her 1st mountain climbing adventure.  Assembled from Sol 3463 pancam high resolution raw images by Marco Di Lorenzo and Ken Kremer.  Credit: NASA/JPL/Cornell/Marco Di Lorenzo/Ken Kremer
The summit of Solander Point
Opportunity rover captured mosaic on Oct. 21, 2013 (Sol 3463) after beginning to ascend the northwestern slope of “Solander Point” on the western rim of Endeavour Crater – her 1st mountain climbing adventure. Assembled from Sol 3463 pancam high resolution raw images by Marco Di Lorenzo and Ken Kremer. Credit: NASA/JPL/Cornell/Marco Di Lorenzo/Ken Kremer

Clay minerals, or phyllosilicates, form in neutral water that is more conducive to life.

At the base of Solander, the six wheeled rover discovered a transition zone between a sulfate-rich geological formation and an older formation. Sulfate-rich rocks form in a wet environment that was very acidic and less favorable to life.

Solander Point is located at the western rim of the vast expanse of Endeavour crater – some 22 kilometers (14 miles) in diameter.

Today marks Opportunity’s 3466th Sol or Martian Day roving Mars – for what was expected to be only a 90 Sol mission.

So far she has snapped over 185,200 amazing images on the first overland expedition across the Red Planet.

Her total odometry stands at over 23.89 miles (38.45 kilometers) since touchdown on Jan. 24, 2004 at Meridiani Planum.

Meanwhile, NASA is in the final stages of processing of MAVEN, the agencies next orbiter.

It is still scheduled to blast off from Cape Canaveral on Nov.18 – see my photos from inside the clean room at the Kennedy Space Center.

MAVEN’s launch was briefly threatened by the government shutdown.

On the opposite side of Mars, Opportunity’s younger sister rover Curiosity is trekking towards gigantic Mount Sharp and recently discovered a patch of pebbles formed by flowing liquid water.

Ken Kremer

Traverse Map for NASA’s Opportunity rover from 2004 to 2013.  This map shows the entire path the rover has driven during nearly 10 years and over 3460 Sols, or Martian days, since landing inside Eagle Crater on Jan 24, 2004 to current location ascending her 1st Martian Mountain - Solander Point - at the western rim of Endeavour Crater.  Opportunity discovered clay minerals at Esperance - indicative of a habitable zone and seeks clay minerals now at Solander. Credit: NASA/JPL/Cornell/ASU/Marco Di Lorenzo/Ken Kremer
Traverse Map for NASA’s Opportunity rover from 2004 to 2013
This map shows the entire path the rover has driven during nearly 10 years and over 3460 Sols, or Martian days, since landing inside Eagle Crater on Jan 24, 2004 to current location ascending her 1st Martian Mountain – Solander Point – at the western rim of Endeavour Crater. Opportunity discovered clay minerals at Esperance – indicative of a habitable zone and seeks clay minerals now at Solander. Credit: NASA/JPL/Cornell/ASU/Marco Di Lorenzo/Ken Kremer

Titan’s North Pole is Loaded With Lakes

Titan's north pole is home to many methane lakes. Credit: NASA

A combination of exceptionally clear weather, the steady approach of northern summer, and a poleward orbital path has given Cassini — and Cassini scientists — unprecedented views of countless lakes scattered across Titan’s north polar region. In the near-infrared mosaic above they can be seen as dark splotches and speckles scattered around the moon’s north pole. Previously observed mainly via radar, these are the best visual and infrared wavelength images ever obtained of Titan’s northern “land o’ lakes!”

 

Titan is currently the only other world besides Earth known to have stable bodies of liquid on its surface, but unlike Earth, Titan’s lakes aren’t filled with water — instead they’re full of liquid methane and ethane, organic compounds which are gases on Earth but liquids in Titan’s incredibly chilly -290º F (-180º C) environment.

While one large lake and a few smaller ones have been previously identified at Titan’s south pole, curiously almost all of Titan’s lakes appear near the moon’s north pole.

Infrared observations of Titan's northern lakes (NASA/JPL-Caltech/SSI)
Infrared observations of Titan’s northern lakes. The cross marks Titan’s geographic north pole. (NASA/JPL-Caltech/SSI)

For an idea of scale, the large lake at the upper right above (and the largest lake on Titan) Kraken Mare is comparative in size to the Caspian Sea and Lake Superior combined. Kraken Mare is so large that sunlight was seen reflecting off its surface in 2009. Punga Mare, nearest Titan’s pole, is 240 miles (386 km) across.

Besides revealing the (uncannily) smooth surfaces of lakes — which appear dark in near-infrared wavelengths but would also be darker than the surrounding landscape in visible light —  these Cassini images also show an unusually bright terrain surrounding them. Since the majority of Titan’s lakes are found within this bright region it’s thought that there could be a geologic correlation; is this Titan’s version of karst terrain, like what’s found in the southeastern U.S. and New Mexico? Could these lakes be merely the visible surfaces of a vast underground hydrocarbon aquifer? Or are they shallow pools filling depressions in an ancient lava flow?

Annotated infrared mosaic of Titan's north pole (NASA/JPL-Caltech/SSI)
Annotated infrared mosaic of Titan’s north pole (NASA/JPL-Caltech/SSI)

Or, are they the remains of once-larger lakes and seas which have since evaporated? The orange-hued regions in the false-color mosaic may be evaporite — the Titan equivalent of salt flats on Earth. The evaporated material is thought to be organic chemicals originally from Titan’s haze particles that were once dissolved in liquid methane.

“Is this an indication that with increased warmth, the seas and lakes are starting to evaporate, leaving behind a deposit of organic material,” wrote Carolyn Porco, Cassini Imaging Team Leader, in an email earlier today. “…in other words, the Titan equivalent of a salt-flat?”

The largest lake at Titan’s south pole, Ontario Lacus, has been previously compared to such an ephemeral lake in Namibia called the Etosha Pan. (Read more here.)

These observations are only possible because of the extended and long-term study of Saturn and its family of moons by the Cassini spacecraft, which began with its establishing orbit in 2004 and has since continued across multiple seasons over a third of the ringed planet’s year. The existence of methane lakes on Titan is undoubtedly fascinating, but how deep the lakes are, where they came from and how they behave in Titan’s environment have yet to be discovered. Luckily, the changing season is on our side.

“Titan’s northern lakes region is one of the most Earth-like and intriguing in the solar system,” said Linda Spilker, Cassini project scientist, based at NASA’s Jet Propulsion Laboratory, Pasadena, Calif. “We know lakes here change with the seasons, and Cassini’s long mission at Saturn gives us the opportunity to watch the seasons change at Titan, too. Now that the sun is shining in the north and we have these wonderful views, we can begin to compare the different data sets and tease out what Titan’s lakes are doing near the north pole.”

The images shown above were obtained by Cassini’s visual and infrared mapping spectrometer (VIMS) during a close flyby of Titan on Sept. 12, 2013.

Read more on the Cassini Imaging Central Laboratory for Operations (CICLOPS) site here and on the NASA site here.

“But how thrilling it is to still be uncovering new territory on this fascinating moon… a place that, until Cassini’s arrival at Saturn nearly 10 years ago, was the largest single expanse of unseen terrain we had remaining in our solar system. Our adventures here have been the very essence of exploration. And it’s not over yet!”

– Carolyn Porco on Facebook

An illustration of a Titanic lake by Ron Miller. All rights reserved. Used with permission.
An illustration of a Titanic lake © Ron Miller. All rights reserved.

Also, check out a corresponding article and intriguing illustration of robotic Titan exploration by space artist extraordinaire Ron Miller on io9.com.