comet Archives

November 7, 2014December 23, 2015 by Tim Reyes

A Comet’s Tale – Rosetta’s Philae, Five Days from Touchdown

Rosetta, the scientific mission to explore a comet's surface. "Ambition", a short Sci-Fi film, set in the near future, and Rosetta, the children's fable, to encourage the next generations to undertake on the great adventures still to come. (Photo Credits: ESA, Platige Image, ESA Communications)

In the recently released Rosetta short film called “Ambition”, the master begins a story to his apprentice – “Once upon a time.” The apprentice immediately objects to his triteness. But he promises that it is worth the slight tribulation. Who could have imagined ten years ago that Rosetta would become so successful in two such contrasting approaches to telling a tale.

The Rosetta mission is part franchise and part scientific mission. In five days, Rosetta will reach a crossroad, a point of no return as epic as moments in Harry Potter or Lord of the Rings. A small mindless little probe called Philae will be released on a one-way trip to the surface of a comet. Win or lose, Philae will live on in the tale of a comet and a mission to uncover the mysteries of our planet’s formation.

ESA did not promise a good mission as Aidan Gillen promises a good story in Ambition. A space mission is never put in terms of a promise but rather it is thousands of requirements and constraints that formulate a mission plan and a spacecraft design. The European Space Agency put 1 billion Euros ($1.3 billion) to work and did so in what now looks like one of the greatest space missions of the first century of space exploration.

The Rosetta mission is actually two missions in one. There is the comet chaser, the orbiter – Rosetta and then the lander Philae. The design of Rosetta’s objectives is some part, probably in large part, was conceived by dismissing the presence of Philae. Make a space probe to a comet that just orbits the small body. Select your scientific instrumentations accordingly. Now add a small lander to the mission profile that will do something extraordinary – what Rosetta cannot do with its instrumentation. Finally, make sure that Rosetta has everything needed to support Philae’s landing on a comet.

Here is what they have as the game plan on November 12^th (the sequence of events begins while its still November 11^th in the Americas). These two times are absolutely non- trivial. They are finely tuned to a timepiece called 67P/Churyumov–Gerasimenko. If calculations were made in error, then Philae’s ultimate fate is unknown. Start exactly on time and Philae will be given the best chance at making a successful touchdown on the comet.

Separation of Philae from Rosetta: 09:03 GMT (10:03 CET)

Touchdown on the comet: 16:02 GMT (17:02 CET).

During this time, comet 67P/Churyumov–Gerasimenko will complete over half a rotation on its axis. To be exact, it will rotate 56.2977% of a full rotation. Comet 67P will have its back turned towards Rosetta as it holds the diminutive Philae for the last time and releases Philae for the first and only time.

Now that the ESA, with help from the graphic artists from Platige Image from Poland, has released something entertaining for the science fiction minded among us, they have again released a next episode in their children’s fable of Rosetta and Philae (video below). This cartoon of the final moments of Rosetta and Philae together preparing for the descent which could well be the final moments of Philae.

Philae could fail, crack like an egg on a sharp rock or topple over a cliff or into a crevasse on the surface of 67P. What happens to Philae will make for a Grimm’s fairy tale ending or something we would all prefer. In either case, the ESA is using graphic arts and storytelling to inspire the next generations to join in what our JFK called “great adventures of all time” [ref].

Through a contest something NASA and JPL have used several times to involve the public, the ESA asked the public to come up with a name for the landing site, site J. Out of the thousands of entries, 150 people suggested the name Agilkia [ref]. Alexandre Brouste from France, the designated winner, has been invited to watch the landing activities at Rosetta’s mission control in Darmstadt, Germany. It follows from the Eqyptian theme of the mission’s two probes. “Rosetta” comes from the clay tablet discovered in the 1800s that led to the deciphering of Egyptian hieroglyphics. Philae” is a island on the Nile which held magnificent Eqyptian temples. With the operation of the Aswan dam starting in 1902, the island of Philae was repeatedly flooded and the temple was at risk. UNESCO beginning in 1960 started a project to save the islands historic structures. They were all moved to a nearby Nile island called Agilkia [related U.T. article]. This becomes a part of the Rosetta story – a lander named Philae in reference to the obelisks used along with the Rosetta stone to decipher Eqyptian writings, departing its mother ship on a short but critical voyage to a final resting place, the landing site now called Agilkia.

Upon landing, a landing confirmation signal is expected from Philae via Rosetta at about 8:02 AM PST (11:02 AM EST, 17:02 Central European Time). Alexandre Brouste of France, the designated winner of the landing site naming contest will be in Darmstadt, Germany in mission control to watch the landing unfold with the Rosetta engineers and scientists. Surely, millions of citizens of the European Union and people worldwide will be watching via the World Wide Web.

The timeline and events to unfold as Philae, the lander is released from Rosetta, the comet orbiter. (Illustration Credit: ESA)

Previous Rosetta and Philae articles at Universe Today

Rosetta’s Philae Lander: A Swiss Army Knife of Scientific Instruments

Why Watch ESA Rosetta’s Movie ‘Ambition’? Because We Want to Know What is Possible

November 6, 2014December 23, 2015 by Bob King

Curiosity Rover Sees a Pixel’s-Worth of Comet Siding Spring

In this panoramic view taken by NASA's Curiosity Rover on October 19th shortly after local sunset (6:11 p.m.), Comet Siding Spring is the single bright pixel at far upper left. Click for a high resolution version. Credit: NASA/JPL-Caltech/Malin Space Science Systems/James Sorenson

When Comet Siding Spring skimmed just 84,500 miles from Mars last month, NASA’s Opportunity and Curiosity Rovers – along with several orbiting Mars spacecraft – readied their cameras to record the historic flyby. Opportunity’s photos revealed a small, fuzzy blob against the stars of Cetus the Whale, but most of us searched in vain to find any trace of the comet among the blizzard of noise in pictures snapped by Curiosity. Yet it may be there after all.

In this before and after animation, you can see how much noise needed to be cleaned from one of the original photos to uncover the the comet. Credit: NASA/JPL-Caltech/Malin Space Science Systems/James Sorenson — In this before-and-after animation, you can see how much noise needed to be cleaned from the original photos to uncover the the comet. Credit: NASA/JPL-Caltech/Malin Space Science Systems/James Sorenson

In this panoramic image at top, assembled and processed by James Sorenson to remove the pervasive noise in the original photos, we see with a twilit landscape just after sundown. Look closely in the upper left hand corner and you’ll see a speck of light. That’s it! Combined with positional information, Sorenson tentatively identified that pixel as Comet C/2013 A1 Siding Spring. OK, it’s not much to look at but may be our best candidate for the hoped-for photo from Curiosity.

Comet Siding Spring near Mars in a composite image by the Hubble Space Telescope, capturing their positions between Oct. 18 8:06 a.m. EDT (12:06 p.m. UTC) and Oct. 19 11:17 p.m. EDT (Oct. 20, 3:17 a.m. UTC). Credit: NASA, ESA, PSI, JHU/APL, STScI/AURA

Remember that conditions were far from ideal when the picture was taken. There was considerable dust and haze in the Martian atmosphere over Gale Crater. Dust effectively absorbs and also scatters light. The bright twilight sky only made the comet more difficult to discern. If you’ve ever struggled to see Mercury at dusk on a hazy summer evening, you’ll understand what our robot was up against.

This animation combines multiple images that were acquired by the HRSC camera on board Mars Express during the comet Siding Spring flyby on October 19, 2014. Click to animate Credit: ESA/DLR/FU Berlin — This single image is one of series that were acquired by the HRSC camera on board Mars Express during the comet Siding Spring flyby on October 19, 2014. Click to animate. Credit: ESA/DLR/FU Berlin

The European Space Agency’s Mars Express orbiter also chimed in with a recent set of comet images. As it flew by, Siding Spring was traveling at around 35 miles per second (56 km/sec) relative to Mars. Images were acquired at 17-second intervals at a resolution of 10.5 miles (17 km) per pixel. What do they show? The irregular shape might make you might think you’re seeing the actual shape of the comet’s nucleus. Unfortunately, that’s impossible because it’s less than a kilometer across and each pixel in the photo spans 17 km. Instead, we’re seeing the combined light of the nucleus and extended coma, the surrounding cloud of gas and dust. Why the images are pure black and white with no grey tones is unclear.

Two photos of comet C/2013 A1 Siding Spring taken 37 minutes apart by the CRISM imager. The subtle coloration of the comet indicates the abundance of different molecules. Credit: NASA / JPL / JHUAPL — Two photos of comet C/2013 A1 Siding Spring taken 37 minutes apart by the CRISM imager when the comet was closest to Mars. The subtle colors seen are likely related to dust grain size or composition. The nucleus itself is not resolved. Credit: NASA/JPL/JHUAPL

Besides the the close-up photo taken with the HiRISE camera on NASA’s Mars Reconnaissance Orbiter, its Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) got busy photographing the dusty inner coma generated when sunlight warms and vaporizes dust-laden ice in the nucleus. The scale of the left image is approximately 2.5 miles (4 km) per pixel; for the right image, it is about 3 miles (5 km) per pixel.

According to NASA, CRISM observed 107 different wavelengths of light in each pixel. Here, only three colors are shown. Researchers think the appearance of color variations in the inner coma could be due to the properties of the comet’s dust, possibly dust grain size or composition. More photos and results from all the spacecraft will appear in the weeks and months ahead as scientists continue their analyses.

Comet Siding Spring shows a condensed coma and a short, faint tail in this photo taken on November 5, 2014. Credit: Alfons Diepvens — Comet Siding Spring shows a condensed coma and hint of a tail in this photo taken on November 5, 2014. Credit: Alfons Diepvens

Comet Siding Spring has left Mars and its crew of robotic eyes behind as it crawls north into the constellation Serpens low in the southwest at dusk. Amateur astronomers are still keen to photograph it at every opportunity. Recent observations indicate a temporary re-brightening, though the comet remains a dim 11th magnitude object.

October 27, 2014December 23, 2015 by Tim Reyes

Why Watch ESA Rosetta’s Movie ‘Ambition’? Because We Want to Know What is Possible

Ambition is a collaboration between Platige Image and ESA. Shot on location in Iceland, it is directed by Tomek Bagi?ski and stars Aiden Gillen and Aisling Franciosi. Does Ambition accomplish more in 7 minutes than Gravity did in 90? Consider the abstraction of the Rosetta mission in light of NASA’s ambitions. (Credit: ESA, Illustration- TRR)

NASA has taken on space missions that have taken years to reach their destination; they have more than a dozen ongoing missions throughout the Solar System and have been to comets as well. So why pay any attention to the European Space Agency’s comet mission Rosetta and their new short film, “Ambition”?

‘Ambition’ might accomplish more in 7 minutes than ‘Gravity’ did in 90.

‘Ambition’ is a 7 minute movie created for ESA and Rosetta, shot on location in Iceland, directed by Oscar-winning Tomek Baginski, and stars Aidan Gillen—Littlefinger of ‘Game of Thrones.’ It is an abstraction of the near future where humans have become demigods. An apprentice is working to merge her understanding of existence with her powers to create. And her master steps in to assure she is truly ready to take the next step.

In the reality of today, we struggle to find grounding for the quest and discoveries that make up our lives on a daily basis. Yet, as the Ebola outbreak or the Middle East crisis reminds us, we are far from breaking away. Such events are like the opening scene of ‘Ambition’ when the apprentice’s work explodes in her face.

The ancient Greeks also took great leaps beyond all the surrounding cultures. They imagined themselves as capable of being demigods. Achilles and Heracles were born from their contact with the gods but they remained fallible and mortal.

The Comet Rendezvous and Flyby Mission conceived in one of two Mariner Mark II spacecraft was abandoned by the US Congress. The American led mission would have accomplished the objectives now being completed by the European Rosetta mission. (Photo Credit: NASA)

But consider the abstraction of the Rosetta mission in light of NASA’s ambitions. As an American viewing the European short film, it reminds me that we are not unlike the ancient Greeks. We have seen the heights of our powers and ability to repel and conquer our enemies, and enrich our country. But we stand manifold vulnerable.

In ‘Ambition’ and Rosetta, America can see our European cousins stepping ahead of us. The reality of the Rosetta mission is that a generation ago – 25 years — we had a mission as ambitious called Comet Rendezvous Asteroid Flyby (CRAF). From the minds within NASA and JPL, twin missions were born. They were of the Mariner Mark II spacecraft design for deep space. One was to Saturn and the other – CRAF was to a comet. CRAF was rejected by congress and became an accepted sacrifice by NASA in order to save its twin, the Cassini mission.

The short film ‘Ambition’ and the Rosetta mission is a reminder of what American ambition accomplished in the 60’s – Apollo, and the 70s – the Viking Landers, but then it began to falter in the 80s. The ambition of the Europeans did not lose site of the importance of comets. They are perhaps the ultimate Rosetta stones of our star system. They are unmitigated remnants of what created our planet billions of years ago unlike the asteroids that remained close to the Sun and were altered by its heat and many collisions.

Artist Illustration of the Cassini space probe to Saturn and Titan, a joint NASA, ESA mission. Cassini was the only Mariner Mark II spacecraft completed. (Photo Credit: NASA)

Our cousins picked up a scepter that we dropped and we should take notice that the best that Europe spawned in the last century – the abstract art of Picasso and Stravinsky, rocketry, and jet travel — remains alive today. Europe had the vision to continue a quest to something quite abstract, a comet, while we chose something bigger and more self-evident, Saturn and Titan.

‘Ambition’ shows us the forces at work in and around ESA. They blend the arts with the sciences to bend our minds and force us to imagine what next and why. There have been American epoch films that bend our minds, but yet sometimes it seems we hold back our innate drive to discover and venture out.

NASA recently created a 7 minute film of a harsh reality, the challenge of landing safely on Mars. ESA and Rosetta’s short film reminds us that we are not alone in the quest for knowledge and discovery, both of which set the stage for new growth and invention. America needs to take heed so that we do not wait until we reach the moment when an arrow pierces our heel as with Achilles and we succumb to our challengers.

References:

Rosetta: The Ambition to turn Science Fiction into Science Fact

October 19, 2014December 23, 2015 by Tim Reyes

A Compendium of Universe Today Comet Siding Spring Articles: January 2013 – October 2014

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.

Universe Today’s Siding Spring Compendium

2014/10/17: Here’s A Look At Comet Siding Spring Two Days Before Its Encounter With Mars

2014/10/17: Weekly Space Hangout Oct 17 2014

2014/10/15: Comet A1 Siding Spring vs Mars Views In Space And Time

2014/10/10: How To See Comet Siding Spring As It Encounters Mars

2014/10/08: Comet Siding Spring Close Call For Mars Wake Up Call For Earth

2014/09/19: How NASA’s Next Mars Spacecraft Will Greet The Red Planet On Sunday

2014/09/09: Tales Tails Of Three Comets

2014/09/05: Maven Mars Orbiter Ideally Poised To Uniquely Map Comet Siding Spring Composition Exclusive Interview With Principal Investigator Bruce Jakosky

2014/08/30: Caterpillar Comet Poses For Pictures En Route To Mars

2014/07/26: NASA Preps For Nail Biting Comet Flyby Of Mars

2014/05/08: Interesting Prospects For Comet A1 Siding Spring Versus The Martian Atmosphere

2014/03/27: Mars Bound Comet Siding Spring Sprouts Multiple Jets

2014/01/29: Neowise Spots Mars Crossing Comet

2014/01/02: Comets Prospects For 2014 A Look Into The Crystal Ball

2013/04/12: New Calculations Effectively Rule Out Comet Impacting Mars In 2014

2013/03/28: NASA Scientists Discuss Potential Comet Impact On Mars

2013/03/05: Update On The Comet That Might Hit Mars

2013/02/26: Is A Comet On A Collision Course With Mars

October 17, 2014December 29, 2015 by Fraser Cain

Weekly Space Hangout – Oct. 17, 2014: Comet Siding Spring & Dark Matter

Host: Fraser Cain (@fcain)

Guests:
Morgan Rehnberg (cosmicchatter.org / @cosmic_chatter)
Continue reading “Weekly Space Hangout – Oct. 17, 2014: Comet Siding Spring & Dark Matter”

October 15, 2014December 23, 2015 by Jason Major

Here’s a High-Res Look at Philae’s Landing Spot

Mosaic of OSIRIS images of landing site "J" on Comet 67P/CG. Credits: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA

The long-awaited deployment of the Philae lander, currently “piggybacked” aboard ESA’s Rosetta spacecraft orbiting the nucleus of Comet 67P/Churyumov-Gerasimenko, will occur in less than a month and we now have our best look yet at the area now green-lighted for touchdown. The picture above, made from two images acquired by Rosetta’s OSIRIS imaging instrument, shows a 500-meter circle centered on “Site J,” a spot on the comet’s “head” carefully chosen by mission scientists as the best place in which Philae should land, explore, and ultimately travel around the Sun for the rest of its days. And as of today, it’s a GO!

Site J was selected from among five other possible sites and was chosen because of the relative safety of its surface, its accessibility to consistent solar illumination, and the scientific and observational data it can make available to Philae’s suite of onboard instruments.

“None of the candidate landing sites met all of the operational criteria at the 100% level, but Site J is clearly the best solution,” said Stephan Ulamec, Philae Lander Manager at the DLR German Aerospace Center.

Illustration of the Rosetta Missions Philae lander on final approach to a comet surface. The date is now set for landing, November 12. (Photo: ESA)

The mosaic above comprises two images taken by Rosetta’s OSIRIS (Optical, Spectroscopic, and Infrared Remote Imaging System) narrow-angle camera on Sept. 14 from a distance of about 30 km (18.6 miles). Image scale is 0.5 m/pixel.

As Comet 67P/CG continues toward perihelion its outgassing and sublimation jetting will undoubtedly increase, and Philae will be getting a front-row seat to the action.

“Site J is just 500-600 meters away from some pits and an area of comet outgassing activity,” said Holger Sierks, principal investigator for Rosetta’s OSIRIS camera from the Max Planck Institute for Solar System Research in Gottingen, Germany. “They will become more active as we get closer to the Sun.”

Watch “Landing on a Comet: the Trailer”

After completing a series of “Go/No-go” decisions by Rosetta’s flight dynamics team, Philae’s separation from Rosetta will occur on Nov. 12 at 08:35 GMT. It will land about seven hours later at around 15:30 GMT. Because of the distance to the comet and spacecraft — about 509 million km — confirmation of a successful touchdown won’t be received on Earth until 28 minutes and 20 seconds later. (And you thought Curiosity’s “seven minutes of terror” was nerve-wracking!)

Landing on a Comet: The Trailer

Artist's impression of the 100-kg Philae lander (screenshot) Credit: ESA/DLR

In less than a month, on November 12, 2014, the 100-kg Philae lander will separate from ESA’s Rosetta spacecraft and descend several kilometers down to the dark, dusty and frozen surface of Comet 67P/Churyumov-Gerasimenko, its three spindly legs and rocket-powered harpoon all that will keep it from crashing or bouncing hopelessly back out into space. It will be the culmination of a decade-long voyage across the inner Solar System, a testament to human ingenuity and inventiveness and a shining example of the incredible things we can achieve through collaboration. But first, Philae has to get there… it has to touch down safely and successfully become, as designed, the first human-made object to soft-land on the nucleus of a comet. How will the little spacecraft pull off such a daring maneuver around a tumbling chunk of icy rubble traveling over 18 km/s nearly 509 million km away? The German Aerospace Center (DLR) has released a “trailer” for the event, worthy of the best sci-fi film. Check it out below.

Want to see more? Of course you do. Keep an eye out for the 11-minute short film “Landing on a Comet – The Rosetta Mission” to be released soon on YouTube here, and follow the latest news from the Rosetta mission here (and here on Universe Today, too!)

“The reason we’re at this comet is for science, no other reason. We’re doing this to get the best science. To characterize this comet has never been done before.”

Original Material: DLR (CC-BY 3.0)
Footage: ESA
Credit 67P image: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA
Music: Omega by TimMcMorris

Source: DLR

October 8, 2014December 23, 2015 by Tim Reyes

Comet Siding Spring: Close Call for Mars, Wake Up Call for Earth?

Five orbiters from India, the European Union and the United States will nestle behind the Mars as comet Siding Springs passes at a speed of 200,000 km/hr (125,000 mph). At right, Comet Shoemaker-Levy 9 impacts on Jupiter, the Chelyabinsk Asteroid over Russia. (Credits: NASA,ESA, ISRO)

It was 20 years ago this past July when images of Jupiter being pummeled by a comet caught the world’s attention. Comet Shoemaker-Levy 9 had flown too close to Jupiter. It was captured by the giant planet’s gravity and torn into a string of beads. One by one the comet fragments impacted Jupiter — leaving blemishes on its atmosphere, each several times larger than Earth in size.

Until that event, no one had seen a comet impact a planet. Now, Mars will see a very close passage of the comet Siding Spring on October 19th. When the comet was first discovered, astronomers quickly realized that it was heading straight at Mars. In fact, it appeared it was going to be a bulls-eye hit — except for the margin of error in calculating a comet’s trajectory from 1 billion kilometers (620 million miles, 7 AU) away.

It took several months of analysis for a cataclysmic impact on Mars to be ruled out. So now today, Mars faces just a cosmic close shave. But this comet packs enough energy that an impact would have globally altered Mars’ surface and atmosphere.

So what should we Earthlings gather from this and other events like it? Are we next? Why or why not should we be prepared for impacts from these mile wide objects?

For one, ask any dinosaur and you will have your answer.

Adding Siding Spring to the Comet 67P atop Los Angeles provides a rough comparison of sizes. This images was expanded upon U.T.'s Bob King - "What Comets, Parking Lots and Charcoal Have in Common". (Credit: ESA, anosmicovni) — An illustration of the Siding Spring comet in comparison to the Comet 67P atop Los Angeles. The original image was the focus of Bob King’s article – “What Comets, Parking Lots and Charcoal Have in Common“. (Credit: ESA, anosmicovni)

One can say that Mars was spared as were the five orbiting spacecraft from India (Mars Orbiter Mission), the European Union (Mars Express) and the United States (MOD, MRO, MAVEN). We have Scottish-Australian astronomer Robert McNaught to thank for discovering the comet on January 3, 2013, using the half meter (20 inch) Uppsala Southern Schmidt Telescope at Siding Spring, Australia.

Initially the margin of error in the trajectory was large, but a series of observations gradually reduced the error. By late summer 2014, Mars was in the clear and astronomers could confidently say the comet would pass close but not impact. Furthermore, as observations accumulated — including estimates of the outpouring of gases and dust — comet Siding Spring shrunk in size, i.e. the estimates of potentially tens of kilometers were down to now 700 meters (4/10th of a mile) in diameter. Estimates of the gas and dust production are low and the size of the tail and coma — the spherical gas cloud surrounding the solid body — are small and only the outer edge of both will interact with Mars’ atmosphere.

The mass, velocity and kinetic energy of celestial bodies can be deceiving. It is useful to compare the Siding Spring comet to common or man-made objects.

Yet, this is a close call for Mars. We could not rule out a collision for over six months. While this comet is small, it is moving relative to Mars at a speed of 200,000 kilometers/hour (125,000 mph, 56 km/sec). This small body packs a wallop. From high school science or intro college Physics, many of us know that the kinetic energy of an object increases by the square of the velocity. Double the velocity and the energy of the object goes up by 4, increase by 3 – energy increases by 9.

So the close shave for Mars is yet another wake up call for the “intelligent” space faring beings of the planet Earth. A wake up call because the close passage of a comet could have just as easily involved Earth. Astronomers would have warned the world of a comet heading straight for us, one that could wipe out 70% of all life as happened 65 million years ago to the dinosaurs. Replace dinosaur with humans and you have the full picture.

Time would have been of the essence. The space faring nations of the world — those of the EU, and Russia, the USA, Japan and others — would have gathered and attempted to conceive some spacecrafts with likely nuclear weapons that could be built and launched within a few months. Probably several vehicles with weapons would be launched at once, leaving Earth as soon as possible. Intercepting a comet or asteroid further out would give the impulse from the explosions more time to push the incoming body away from the Earth.

There is no way that humanity could sit on their collective hands and wait for astronomers to observe and measure for months until they could claim that it would just be a close call for Earth. We could imagine the panic it would cause. Recall the scenes from Carl Sagan’s movie Contact with people of every persuasion expressing at 120 decibels their hopes and fears. Even a small comet or asteroid, only a half kilometer – a third of a mile in diameter would be a cataclysmic event for Mars or Earth.

But yet, in the time that has since transpired from discovery of the comet Siding Spring (1/3/2013), the Chelyabinsk asteroid (~20 m/65 ft) exploded in an air burst that injured 1500 people in Russia. The telescope that discovered Comet Siding Spring was decommissioned in late 2013 and the Southern Near-Earth Object Survey was shutdown. This has left the southern skies without a dedicated telescope for finding near-Earth asteroids. And proposals such as the Sentinel project by the B612 Foundation remain underfunded.

We know of the dangers from small celestial bodies such as comets or asteroids. Government organizations in the United States and groups at the United Nations are discussing plans. There is plenty of time to find and protect the Earth but not necessarily time to waste.

Previous U.T. Siding Spring stories:
“What Comets, Parking Lots and Charcoal Have in Common“, Bob King, Sept 5, 2014
“MAVEN Mars Orbiter Ideally Poised to Uniquely Map Comet Siding Spring Composition
– Exclusive Interview with Principal Investigator Bruce Jakosky”, Ken Kremer“, Sept 5, 2014
“NASA Preps for Nail-biting Comet Flyby of Mars“, BoB King, July 26,2014

October 3, 2014December 23, 2015 by Bob King

Rosetta’s Comet in Thrilling 3-D

3D view created by Mattias Malmer of the recent ESA image (below) showing multiple jets of gas and dust spraying from Comet 67P/Churyumov-Gerasimenko. Grab your red-blue plastic glasses and prepare to enter another dimension. Malmer created the view by draping a navigation camera image over a 3D model of the comet and then photographing it from two slightly different perspectives. Click for large version. Credit: ESA/Rosetta/NAVCAM/processing by Mattias Malmer

She’s gonna blow! Rosetta’s navigation camera recently grabbed our best view yet of the geyser-like jets spraying from the nucleus of Comet 67P/Churyumov-Gerasimenko. They were taken on September 26 as the spacecraft orbited the comet at a distance of just 16 miles (26 km) and show jets of water vapor and dust erupting from several discrete locations beneath the surface along the neck region of the comet’s nucleus. Mattias Malmer, a 3D technical director, created the spectacular 3D views by draping the navigation camera images over a 3D model of the comet and then photographing it from two slightly different perspectives.

Jets of gas and dust are seen escaping comet 67P/C-G on September 26 in this four-image mosaic. Click to enlarge. Credit: ESA/Rosetta/NAVCAM

Jets form when the sun warms the comet’s coal-black surface, causing ices beneath to sublimate or change directly from solid to gas without becoming liquid. This is possible because of the near-zero atmospheric pressure at the comet. Pressure builds in the pockets of gas until they find escape through cracks or pores as plume-like jets. Comet dust along with the gas fashions the coma and tail over time. Something similar happens when you shake up a bottle of champagne and then loosen the cork. Trapped carbon dioxide (what makes the “fizz”) blasts the cork across the room.

Comet Churyumov-Gerasimenko rotating from darkness into light. (Mattias Malmer)

If you liked the still images, check out these videos by Malmer. He used the same draping technique and then animated the stills. Be sure to stop by his Cascade of Light blog for more images and videos when you get a chance.

Comet Churyumov-Gerasimenko rotating in 3D (Mattias Malmer)

I saved the best for last. What majesty!

3D rotation of Comet 67P/C-G with jets (Mattias Malmer)

September 29, 2014December 23, 2015 by Bob King

PanSTARRS K1, the Comet that Keeps Going and Going and Going

Comet C/2012 K1 PANSTARRS photographed on September 26, 2014 by Rolando Ligustri. Like most comets, we see two tails. K1's dust tails points off to the left, it's gas or ion tail to the right. Credit: Rolando Ligustri

Thank you K1 PanSTARRS for hanging in there! Some comets crumble and fade away. Others linger a few months and move on. But after looping across the night sky for more than a year, this one is nowhere near quitting. Matter of fact, the best is yet to come.

This new visitor from the Oort Cloud making its first passage through the inner solar system, C/2012 K1 was discovered in May 2012 by the Pan-STARRS 1 survey telescope atop Mt. Haleakala in Hawaii at magnitude 19.7. Faint! On its the inbound journey from the Oort Cloud, C/2012 K1 approached with an orbit estimated in the millions of years. Perturbed by its interactions with the planets, its new orbit has been reduced to a mere ~400,000 years. That makes the many observing opportunities PanSTARRS K1 has provided that much more appreciated. No one alive now will ever see the comet again once this performance is over.

Comet C/2012 K1 PanSTARRS' changing appearance over the past year. Credit upper left clockwise: Carl Hergenrother, Damian Peach, Chris Schur and Rolando Ligustri — Comet C/2012 K1 PanSTARRS’ changing appearance over the past year. Credit upper left clockwise: Carl Hergenrother, Damian Peach, Chris Schur and Rolando Ligustri

Many amateur astronomers first picked up the comet’s trail in the spring of 2013 when it had brightened to around magnitude 13.5. My observing notes from June 2, 2013, read:

“Very small, about 20 arc seconds in diameter. Pretty faint at ~13.5 and moderately condensed but not too difficult at 142x . Well placed in Hercules.” Let’s just say it was a faint, fuzzy blob.

K1 PanSTARRS slowly brightened in Serpens last fall until it was lost in evening twilight. Come January this year it returned to the morning sky a little closer to Earth and Sun and a magnitude brighter. As winter snow gave way to frogs and flowers, the comet rocketed across Corona Borealis, Bootes and Ursa Major. Its fat, well-condensed coma towed a pair of tails and grew bright enough to spot in binoculars at magnitude 8.5 in late May.

Skywatchers can find C/2012 K1 PanSTARRS in the morning just in Hydra-Puppis just before dawn. The map shows its location daily with stars to magnitude 8.5. The numbers next to some stars are standard Flamsteed atllas catalog numbers. Source: Chris Marriott's SkyMap — Skywatchers can find C/2012 K1 PanSTARRS in the morning sky in the Hydra and Puppis just before dawn when it’s highest in the southeastern sky. The map shows its location daily with stars to magnitude 8.5. The numbers next to some stars are standard Flamsteed atlas catalog numbers. Click for a larger version. Source: Chris Marriott’s SkyMap

By July, it hid away in the solar glare a second time only to come back swinging in September’s pre-dawn sky. Now in the constellation Hydra and even closer to Earth, C/2012 K1 has further brightened to magnitude 7.5. Though low in the southeast at dawn, I was pleasantly surprised to see it several mornings ago. Through my 15-inch (37-cm) reflector at 64x I saw a fluffy, bright coma punctuated by a brighter, not-quite-stellar nucleus and a faint tail extending 1/4º to the northeast.

Mid-northern observers can watch the comet’s antics through mid-October. From then on, K1 will only be accessible from the far southern U.S. and points south as it makes the rounds of Pictor, Dorado and Horologium. After all this time you might think the comet is ready to depart Earth’s vicinity. Not even. C/2012 K1 will finally make its closest approach to our planet on Halloween (88.6 million miles – 143 million km) when it could easily shine at magnitude 6.5, making it very nearly a naked-eye comet.

PanSTARRS K1’s not giving up anytime soon. Southern skywatchers will keep it in view through the spring of 2015 before it returns to the deep chill from whence it came. After delighting skywatchers for nearly two years, it’ll be hard to let this one go.