This colorized mosaic from NASA's Cassini mission shows the most complete view yet of Titan's northern land of lakes and seas. Saturn's moon Titan is the only world in our solar system other than Earth that has stable liquid on its surface. The liquid in Titan's lakes and seas is mostly methane and ethane. Image credit: NASA/JPL-Caltech/ASI/USGS
There’s a very early-stage NASA concept to take a submarine and dive into a lake of Titan, that moon of Saturn that has chemistry that could prove to be a similar precursor to what eventually formed life on Earth. The moon has weather and a hydrological system and an atmosphere, making it an exciting location for astrobiologists.
Luckily for scientists, the Cassini spacecraft beams back regular updates on what it sees at Titan. And this week comes yet another opportunity, as the machine whizzes by the moon to look for “mirror-like surface echoes” in a lake-filled region in Titan’s northern sector.
Principal among the targets will be Kraken Mare, a liquid hydrocarbon sea that is about five times the size of Lake Superior in North America. It’s an astounding 154,000 square miles (400,000 square kilometers). On this pass, Cassini is going to sail over the eastern area of the sea.
“Measurements of the absolute strength of the echo and its polarization properties, when detectable, yield important information about the surface status (liquid/solid), surface reflectivity, surface dielectric constant and implied composition, and surface roughness,” Cassini’s website says in a description of the T-106 flyby, which will take place Thursday (Oct. 23).
Saturn’s moon Titan with Tethys hovering in the background. Image taken by the Cassini spacecraft. Credit: NASA/JPL/Space Science Institute
This is the second-to-last flyby Cassini will have of Titan in 2014, with the last one coming Dec. 10. In that case, the focus will be learning more about Titan’s atmosphere to learn more about measurement differences obtained by instruments on Cassini.
This past week, meanwhile, Titan has been busy looking at Saturn. It examined a northern aurora, looked at the planet’s F ring, and also searched for small satellites.
Scientists have been working at Saturn for the past 10 years with the Cassini mission, which is now entering a new phase as Saturn enters northern summer. This is expected to produce more changes on Titan, such as winds picking up, as more sunlight strikes the surface and atmosphere.
Is this an image of Comet Siding Spring? It's the only fuzzy object in the field photographed on Sol 3817 (October 19) by the Opportunity Rover. Click for original raw image.
It looks like NASA’s hard-working Opportunity Rover nabbed our very first pictures of a comet seen from another world! A study of raw images taken by the rover turned up a very promising fuzzy object. Only three night sky pictures were posted today, but two clearly show a fuzzy spot near the center of the field. Stars show as points of light and there are what appear to be a smattering of cosmic ray hits, but in the photo above, the brightest object is slightly elongated (trailed during the exposure?) and cometary in appearance.
Here’s another photo:
A second picture from Opportunity possibly showing the comet. Click for original. Credit: NASA/JPL-Caltech
Looking back over earlier photos of the sky taken on Sol 3212 show only stars and no fuzzy blobs. The pictures were taken around 4:13 a.m. local time with the Sun 25 degrees below the horizon. Opportunity can photograph diffuse objects as dim as the Andromeda Galaxy at magnitude +3.5 and stars down to magnitude +6 or +7. That’s similar to what we see on Earth on very dark night. Since the comet glowed far brighter at around magnitude -5 by some estimates, it would be a relatively easy catch for the rover panoramic camera.
Curiousity Navcam photo of the sky on October 19, 2014, shows the silhouetted rim of Gale Crater and lots of noise. Credit: NASA/JPL-Caltech
NASA has also posted images taken by the Curiosity Rover but for the life of me I can’t find any sign of the Comet Siding Spring. Maybe it’ll pop out after the noise is removed. We’ll keep you posted.
Another Curiosity photo of the sky. If you look closely you’ll see stars among the noise. Click for original Credit: NASA/JPL-Caltech
The Rosetta spacecraft takes a selfie Oct. 7 with its target, 67P/Churyumov–Gerasimenko, from an altitude of about 9.9 miles (16 kilometers). Credit: ESA/Rosetta/Philae/CIVA
The Philae spacecraft has a tough job ahead of it on November 12: it is slated to make the first landing on a comet’s surface. Riding piggyback on the Rosetta spacecraft, all indications are it is in good health and ready for the job; the team has even been taking the time for Philae to image spacecraft “selfies” with its target, Comet 67P/Churyumov–Gerasimenko, in the background.
And Rosetta will also be working hard, as the animation above shows us with the various maneuvers the spacecraft will be required to send Philae to the surface. Read more about these orbital changes below, as well as details of a contest to name the comet’s landing site.
As you can see in the animation, Rosetta starts in a 19 kilometer (11.8 mile) orbit, then moves down to the 10 km (6.2 mile) mapping orbit that it is right now.
Rosetta then does some maneuvers to get ready to send Philae to the surface, including a trajectory change about 2-3 hours before Philae’s landing. Rosetta will be about 22.5 km (14 miles) from the comet during the pre-separation phase. Then, the latter part of the animation shows Rosetta moving around to orbits ranging between 20 km and 50 km (12.4 miles and 18.6 miles) through December.
Meanwhile, here’s another way that certain people can get involved in the mission: the European Space Agency has a naming contest for the prime landing site!
“The rules are simple: any name can be proposed, but it must not be the name of a person,” ESA stated. “The name must be accompanied by a short description (up to 200 words) explaining why this would make the ideal name for such an historic location.”
Full contest rules and details are available here. Hurry as the deadline is Oct. 22!
A false-color view of Saturn's moon Hyperion taken during a Cassini flyby in September 2005. Credit: NASA/JPL-Caltech/Space Science Institute
Ever taken a balloon and rubbed it against your hair? That’s an example of electrostatic charging, which you see as the balloon briefly attracts strands of hair against your head. Turns out a similar process is taking place on Saturn’s moon Hyperion. More astounding, it wasn’t until recently that scientists saw a curious effect on the Cassini spacecraft in 2005.
As the machine whizzed by the small moon, Cassini was blanketed in electrons from Hyperion’s electrostatically charged surface. It’s the first time scientists have seen static electricity in effect on any airless body outside of the Moon.
The charge comes partly from massive Saturn’s magnetic field, which hits Hyperion’s spongy surface constantly with electrons and ions. The Sun also plays a role, sending ultraviolet light that also strikes the moon’s surface. Scientists found out this happens while studying old data on the Cassini spacecraft, when they discovered “something unexpected” during a close flyby of Hyperion in September 2005.
NASA’s Cassini spacecraft obtained this unprocessed image of Saturn’s moon Hyperion on Aug. 25, 2011. Image credit: NASA/JPL-Caltech/Space Science Institute
Specifically, the spacecraft — which is still in operation today — was briefly connected through magnetism to Hyperion’s surface, receiving a surge of electrons. Cassini emerged from the encounter unharmed, even though team members estimate that it received the equivalent of a 200-volt shock from the moon. Charging events can hurt spacecraft, making this a valuable thing to know about for future missions.
“Our observations show that this is also an important effect at outer planet moons and that we need to take this into account when studying how these moons interact with their environment,” stated Geraint Jones of Mullard Space Science Laboratory (MSSL), University College London. He is a member of the Cassini Plasma Spectrometer (CAPS) team and one of the study’s supervisors.
CAPS is not in operation any more, since the instrument was turned off due to drawing excess current in 2012. But perhaps some of its past data, and observations from other Cassini instruments, can help unveil evidence of charging on other moons.
The tumbling motion of elongated Eros creates a changing brightness. (via transitofvenus.nl)
Previous research concerning some of Saturn’s moons, and the asteroid Eros, suggests that charged dust can move across the surface and perhaps even be able to sail into space against the force of gravity.
Several other instruments were used to gather data for this analysis, including Cassini’s magnetometer, magnetospheric imaging instrument, and radio and plasma wave science instrument.
You can read more about the research, which was led by Tom Nordheim, an MSSL doctoral candidate, in Geophysical Research Letters.
Comet Siding Spring approaches within a degree of Mars at 5:07 a.m. CDT today October 19. Closest approach happens around 1:28 p.m. CDT (18:28 UT) when the comet will brush about 83,240 miles from the planet's surface. Image copyright SEN / Damian Peach
Astrophotographer Damian Peach shares this spectacular image of comet C/2013 A1 Siding Spring approaching Mars taken just hours ago. The faint comet shows a small, condensed coma and bent tail against the glaring orange glow of the brilliant planet. Most photos of comets passing by a planet or deep sky object are lucky line-of-sight pairings with the comet in the foreground and object light years away in the background. Not this one. Both Siding Spring and Mars lie at nearly the identical distance from Earth of 151 million miles (243 million km).
Artist view of the comet passing closest to Mars this afternoon October 19. At the time, the Mars orbiters from the U.S., Europe and India will be huddled on the opposite side of the planet to avoid possible impacts from comet dust. Credit: NASA
When closest to Mars this afternoon, Siding Spring is expected to shine at around magnitude -5 or about twice as bright as Venus. Mind you, that estimate considers the entire comet crunched down into a dot. But for those who remember, Comet Hale-Bopp remained at zero magnitude, 100 times fainter than Siding Spring, and made for one of the most impressive naked eye sights on spring evenings in 1997.
More recently, Comet McNaught climaxed at magnitude -5 in the daytime sky near the Sun in January 2007. It was plainly visible in binoculars and telescopes in a blue sky if you knew exactly where to look and took care to avoid the Sun. Would-be Martians are far more fortunate, with Siding Spring appearing high overhead in a dark sky from some locations, including that of NASA’s Curiosity Rover.
Comet C/2013 Siding Spring as it rises and sets over the Curiosity Rover this weekend October 18-19. Credit: Solarsystemscope.com
Right on time for today’s encounter, the folks at Solarsystemscope.com have rolled out an interactive simulation of Comet Siding Spring’s appearance in the sky above Curiosity. Just click the play button on the control panel above to run it live. Seen from Mars, the comet bobs along Eridanus the River southwest of Orion, passing high in the southern sky overnight. What a sight!
Another photo, just in, taken of the comet and Mars today by Rolando Ligustri. Beautiful!
The comet nucleus is only about 0.4 miles (700 meters) across, but the coma or atmosphere fluffs out to around 12,000 miles (19,300 km). Seen from the ground, Siding Spring would span about 8°of sky or 16 full Moons from head to tail. Moving at 1.5° per minute, we could watch crawl across the heavens in real time with the naked eye. Wish I zoom to Mars for a look, but the rovers and orbiters will be our eyes as they study and photograph the comet during its brief flyby. As soon as those pictures become available, we’ll publish them here. Can’t wait!
Come Siding Spring comes out the other side!
While we’re waiting, amateur astronomers have been busy shooting additional photos and creating videos from their images. Fritz Helmut Hemmerich made this video from 1200-meters at Tenerife in the Canary Islands showing Comet Siding Spring immediately after its Mars encounter. One thing we know for certain is that the comet is intact after its close brush.
Negative image showing Comet Siding Spring closely approaching Mars today. Credit: Peter Lake
And find our more amazing photos and information at Sen TV, and you can follow them on Twitter at @sen.
Comet C/2013 A1 Siding Spring passed between the Small Magellanic Cloud (left) and the rich globular cluster NGC 130 on August 29, 2014. Credit: Rolando Ligustri
We present here a compendium of Universe Today articles on comet Siding Spring. Altogether 18 Universe Today stories and counting have represented our on-going coverage of a once in a lifetime event. The articles beginning in February 2013, just days after its discovery, lead to the comet’s penultimate event – the flyby of Mars, October 19, 2014. While comet Siding Spring will reach perihelion just 6 days later, October 25, 2014, it will hardly have sensed the true power and impact that our Sun can have on a comet.
Siding Spring’s Oort Cloud cousin, Comet ISON in November 2013 encountered the Sun at a mere 1.86 million km. The intensity of the Sun’s glare was 12,600 times greater than what Siding Spring will experience in a few days. Comet ISON did not survive its passage around the Sun but Comet Siding Spring will soon turn back and begin a very long journey to its place of origin, the Oort Cloud far beyond Pluto.
An animation of comet Siding Springs passage through the inner Solar System. The scale size of its place of origin would dwarf the orbits of the Solar System to little more than a small dot. (Illustration Credit: Near-Earth Object (NEO) office, NASA/JPL)
The closest approach for comet Siding Spring with the Sun – perihelion is at a distance of 1.39875 Astronomical Units (1 AU being the distance between the Earth and Sun), still 209 million km (130 million miles). The exact period of the comet is not exactly known but it is measured in millions of years. In my childhood astronomy book, it stated that comet Halley, when it is at its furthest distance from the Sun, is moving no faster than a galloping horse. This has also been all that comet Siding Spring could muster for millions of years – the slightest of movement in the direction of the Sun.
It is only in the last 3 years, out all the millions spent on its journey, that it has felt the heat of the Sun and been in proximity to the planetary bodies of our Solar System. This is story of all long period comets. A video camera on Siding Spring would have recorded the emergence and evolution of one primate out of several, one that left the trees to stand on two legs, whose brain grew in size and complexity and has achieved all the technological wonders (and horrors) we know of today.
Now with its close encounter with Mars, the planet’s gravity will bend the trajectory of the comet and reduce its orbital period to approximately one million years. No one will be waiting up late for its next return to the inner Solar System.
It is also unknown what force in the depths of the Oort cloud nudged the comet into its encounter with Mars and the Sun. Like the millions of other Oort cloud objects, Siding Spring has spent its existence – 4.5 Billion years, in the darkness of deep space, with its parent star, the Sun, nothing more than a point of light, the brightest star in its sky. The gravitational force that nudged it may have been a passing star, another cometary body or possibly a larger trans-Neptunian object the size of Pluto and even as large as Mars or the Earth.
The forces of nature on Earth cause a constant turning over geological features. Our oceans and atmosphere are constantly recycling water and gases. The comets that we receive from the Oort Cloud are objects as old as our Solar System. Yet it is the close encounter with Mars that has raised the specter of an otherwise small ordinary comet. All these comets from deep space are fascinating gems nearly unaltered for 1/3rd of the time span of the known Universe.
Not only will the Mars orbiters gather information about the comet and its dust before, during and after the encounter, a fleet of additional telescopes will make the most of the rare opportunity. Credit: NASA.
Comet Siding Spring will pass close to Mars today, Sunday, October 19, at 18:32 UTC. The comet will come within 139,500 km (87,000 miles) of the Red Planet, which is sixteen times closer to Mars than any known comet has ever come to Earth. About 100 minutes after the closest approach, the densest part of the comet’s tail will pass Mars’ location. You can watch live below courtesy of Slooh, ESA and the Virtual Telescope, below:
Slooh will feature two shows. The first show, billed “Close Call – Comet Siding Spring Zips by Mars,” will start at 11:15 AM PDT / 2:15 PM EDT / 18:15 UTC – International times here where Slooh will track Comet Siding Spring on close-approach live from South Africa and later from the Canary Islands. The second show, billed “Comet Siding Spring – the Outcome” will start at 5:30 PM PDT / 8:30 PM EDT / 00:30 UTC (10/20) – International times here – where Slooh will continue to track the comet live from Slooh’s southern observatory located at the Catholic University (PUC) – both shows will feature expert commentary by esteemed astrobiologist David Grinspoon and Slooh host Geoff Fox. The latter show will feature a special discussion with Slooh astronomer Bob Berman, who will be on location in Chile. Viewers can ask questions during each show by using hashtag #SloohComet.
Recovery crew members process the X-37B Orbital Test Vehicle at Vandenberg Air Force Base after completing 674 days in space. A total of three X-37B missions have been completed, totaling 1,367 days on orbit. Photo: Boeing
Recovery crew members process the X-37B Orbital Test Vehicle at Vandenberg Air Force Base after completing 674 days in space. A total of three X-37B missions have been completed, totaling 1,367 days on orbit. Photo: Boeing Watch cool landing video below[/caption]
The US Air Force’s unmanned, X-37B military space plane made an autonomous runway landing on Friday, Oct. 17, at Vandenberg Air Force Base, Calif., concluding an orbital test flight nearly two years in duration on a record breaking mission whose goals are shrouded in secrecy.
The Boeing-built X-37B, also known as the Orbital Test Vehicle (OTV), successfully fired its baking thrusters, plunged through the atmosphere, endured scorching re-entry heating and safely rolled to touch down on Vandenberg Air Force Base at 9:24 a.m. PDT Friday, concluding a clandestine 674-day experimental test mission for the U.S. Air Force Rapid Capabilities Office.
This was the third flight of an X-37B OTV vehicle on a mission known as OTV-3.
“I’m extremely proud of our team for coming together to execute this third safe and successful landing,” said Col Keith Balts, 30th Space Wing commander, in a statement.
“Everyone from our on console space operators to our airfield managers and civil engineers take pride in this unique mission and exemplify excellence during its execution.”
Nothing is known about the flights objectives or accomplishments beyond testing the vehicle itself.
The OTV is somewhat like a miniature version of NASA’s space shuttles. Boeing has built two OTV vehicles.
The reusable space plane is designed to be launched like a satellite and land on a runway like an airplane and a NASA space shuttle. The X-37B is one of the newest and most advanced reentry spacecraft.
A third mission of the Boeing-built X-37B Orbital Test Vehicle was completed on Oct. 17, 2014, when it landed and was recovered at Vandenberg Air Force Base, Calif, following a successful 674-day space mission. Photo: Boeing
OTV-3 also marked the first reflight of an OTV vehicle, to test its re-usability.
The OTV-3 mission was launched from Cape Canaveral Air Force Station, Fla., on Dec. 11, 2012, encapsulated inside the payload fairing atop a United Launch Alliance Atlas V rocket from Space Launch Complex 41.
Among the primary mission goals of the first two flights were check outs of the vehicles capabilities and reentry systems and testing the ability to send experiments to space and return them safely.
It is not known if the X-37B conducted reconnaissance activities during the test flights. It does have the capability to deploy satellites in space.
All three OTV missions have launched from Cape Canaveral and landed at Vandenberg.
The first OTV mission launched on April 22, 2010, and concluded on Dec. 3, 2010, after 224 days in orbit. The second OTV mission began March 5, 2011, and concluded on June 16, 2012, after 468 days on orbit.
Here’s a video of the OTV-3 landing:
Video Caption: The X-37B Orbital Test Vehicle mission 3 (OTV-3), the Air Force’s unmanned, reusable space plane, landed at Vandenberg Air Force Base at 9:24 a.m. Oct. 17. Credit: USAF
“The 30th Space Wing and our mission partners, Air Force Rapid Capabilities Office, Boeing, and our base support contractors, have put countless hours of hard work into preparing for this landing and today we were able to see the culmination of that dedication,” said Balts.
The 11,000 pound state-of -the art reusable OTV space plane was built by Boeing and is about a quarter the size of a NASA space shuttle. It was originally developed by NASA but was transferred to the Defense Advanced Research Projects Agency (DARPA) in 2004.
Altogether, the OTV vehicles have spent 1,334 days in Earth orbit.
The OTV’s can stay on orbit far longer than NASA’s shuttles since their power is supplemented by solar panels deployed from the vehicles open cargo bay.
“The landing of OTV-3 marks a hallmark event for the program” said the X-37B program manager. “The mission is our longest to date and we’re pleased with the incremental progress we’ve seen in our testing of the reusable space plane. The dedication and hard work by the entire team has made us extremely proud.”
“With a program total of 1,367 days on orbit over three missions, these agile and powerful small space vehicles have completed more days on orbit than all 135 Space Shuttle missions combined, which total 1,334 days,” said Ken Torok, Boeing director of Experimental Systems, in a statement.
Recovery crew members process the X-37B Orbital Test Vehicle at Vandenberg Air Force Base after completing 674 days in space. A total of three X-37B missions have been completed, totaling 1,367 days on orbit. Photo: Boeing
“The X-37B is the newest and most advanced re-entry spacecraft. Managed by the Air Force Rapid Capabilities Office, the X-37B program performs risk reduction, experimentation and concept of operations development for reusable space vehicle technologies,” according to an Air Force statement.
The Air Force says that the next X-37B launch on the OTV-4 mission is due to liftoff from Cape Canaveral sometime in 2015.
Stay tuned here for Ken’s continuing Earth and Planetary science and human spaceflight news.
US Air Force X-37B OTV-2 mini space shuttle is encapsulated in 5 meter payload fairing and bolted atop an Atlas 5 rocket at Pad 41 at Cape Canaveral Air Force Station, Florida prior to 5 March 2011 launch. This up close view of the nose cone holding the secretive X-37B shows the umbilical line attachments. Credit: Ken Kremer
Comet 2013 A1 Siding Spring on October 17, 2014, with two days to go until its Martian encounter. Very dense Milkyway starfield in the background with many darker obscured regions. Credit and copyright: Damian Peach.
The excitement continues to build as Comet Siding Spring rapidly approaches the Red Planet, and here’s the latest view of the comet from prolific astrophotographer Damian Peach. While Comet Siding Spring’s encounter with Mars on October 19 will not be visible from Earth with the unaided eye, skywatchers in mid-northern latitudes, can now view the comet; an 8-inch (20 cm) or larger telescopes is needed to follow the comet as it travels from Scorpius north to Ophiuchus and its encounter with Mars on October 19.
The comet will come within 139,500 km (86,000 miles) above the planet’s surface on Sunday.
As our David Dickinson discussed earlier this week, if you were an astronaut stranded on the surface of Mars, the comet’s passage would be a spectacular sight under the dark Martian sky. Some scientists suggest it could even spawn a short but brilliant meteor shower caused by cometary dust grains plunging into the Martian atmosphere.
The spacecraft in orbit around Mars will be watching Comet Siding Spring too. The fleet of spacecraft from ESA, NASA and ISRO will hide behind the Red Planet on Sunday morning, trying to avoid possible bombardment by tiny grains of dust from the comet. But before and after that, the spacecraft will attempt to gather data on the comet as well as try to measure how the gas and dust interact with the Martian atmosphere.
Stay tuned for news on the comet’s encounter with Mars.
