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

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.
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

MAVEN Mars Orbiter Ideally Poised to Uniquely Map Comet Siding Spring Composition – Exclusive Interview with Principal Investigator Bruce Jakosky

MAVEN to conduct up close observations of Comet Siding Spring during Oct. 2014
MAVEN is NASA’s next Mars Orbiter and will investigate how the planet lost most of its atmosphere and water over time. Credit: NASA
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NASA’s MAVEN Mars Orbiter is “ideally” instrumented to uniquely “map the composition of Comet Siding Spring” in great detail when it streaks past the Red Planet during an extremely close flyby on Oct. 19, 2014 – thereby providing a totally “unexpected science opportunity … and a before and after look at Mars atmosphere,” Prof. Bruce Jakosky, MAVEN’s Principal Investigator of CU-Boulder, CO, told Universe Today in an exclusive interview.

The probes state-of-the-art ultraviolet spectrograph will be the key instrument making the one-of-a-kind compositional observations of this Oort cloud comet making its first passage through the inner solar system on its millions year orbital journey.

“MAVEN’s Imaging Ultraviolet Spectrograph (IUVS) is the ideal way to observe the comet coma and tail,” Jakosky explained.

“The IUVS can do spectroscopy that will allow derivation of compositional information.”

“It will do imaging of the entire coma and tail, allowing mapping of composition.”

Comet: Siding Spring. The images above show -- before and after filtering -- comet C/2013 A1, also known as Siding Spring, as captured by Wide Field Camera 3 on NASA's Hubble Space Telescope.  Image Credit: NASA, ESA, and J.-Y. Li (Planetary Science Institute)
Comet: Siding Spring
The images above show — before and after filtering — comet C/2013 A1, also known as Siding Spring, as captured by Wide Field Camera 3 on NASA’s Hubble Space Telescope. Image Credit: NASA, ESA, and J.-Y. Li (Planetary Science Institute)

Moreover the UV spectrometer is the only one of its kind amongst NASA’s trio of Martian orbiters making its investigations completely unique.

“IUVS is the only ultraviolet spectrometer that will be observing the comet close up, and that gives the detailed compositional information,” Jakosky elaborated

And MAVEN, or the Mars Atmosphere and Volatile Evolution, is arriving just in the nick of time to fortuitously capture this fantastically rich data set of a pristine remnant from the solar system’s formation.

The spacecraft reaches Mars in less than 15 days. It will rendezvous with the Red Planet on Sept. 21 after a 10 month interplanetary journey from Earth.

Furthermore, since MAVEN’s purpose is the first ever detailed study of Mars upper atmosphere, it will get a before and after look at atmospheric changes.

“We’ll take advantage of this unexpected science opportunity to make observations both of the comet and of the Mars upper atmosphere before and after the comet passage – to look for any changes,” Jakosky stated.

How do MAVEN’s observations compare to NASA’s other orbiters Mars Odyssey (MO) and Mars Reconnaissance Orbiter (MRO), I asked?

“The data from the other orbiters will be complementary to the data from IUVS.”

“Visible light imaging from the other orbiters provides data on the structure of dust in the coma and tail. And infrared imaging provides information on the dust size distribution.”

IUVS is one of MAVENS’s nine science sensors in three instrument suites targeted to study why and exactly when did Mars undergo the radical climatic transformation.

How long will MAVEN make observations of Comet C/2013 A1 Siding Spring?

“We’ll be using IUVS to look at the comet itself, about 2 days before comet nucleus closest approach.”

“In addition, for about two days before and two days after nucleus closest approach, we’ll be using one of our “canned” sequences to observe the upper atmosphere and solar-wind interactions.”

“This will give us a detailed look at the upper atmosphere both before and after the comet, allowing us to look for differences.”

Describe the risk that Comet Siding Spring poses to MAVEN, and the timing?

“We have the encounter with Comet Siding Spring about 2/3 of the way through the commissioning phase we call transition.”

“We think that the risk to the spacecraft from comet dust is minimal, but we’ll be taking steps to reduce the risk even further so that we can move on toward our science mission.”

“Throughout this entire period, though, spacecraft and instrument health and safety come first.”

This graphic depicts the orbit of comet C/2013 A1 Siding Spring as it swings around the sun in 2014. On Oct. 19, 2014 the comet will have a very close pass at Mars. Its nucleus will miss Mars by about 82,000 miles (132,000 kilometers).   Credit: NASA/JPL-Caltech
This graphic depicts the orbit of comet C/2013 A1 Siding Spring as it swings around the sun in 2014. On Oct. 19, 2014 the comet will have a very close pass at Mars. Its nucleus will miss Mars by about 82,000 miles (132,000 kilometers). Credit: NASA/JPL-Caltech

What’s your overall hope and expectation from the comet encounter?

“Together [with the other orbiters], I’m hoping it will all provide quite a data set!

“From Mars, the comet truly will fill the sky!” Jakosky gushed.

The comet’s nucleus will fly by Mars at a distance of only about 82,000 miles (132,000 kilometers) at 2:28 p.m. ET (18:28 GMT) on Oct. 19, 2014. That’s barely 1/3 the distance from the Earth to the Moon.

What’s the spacecraft status today?

“Everything is on track.”

Maven spacecraft trajectory to Mars. Credit: NASA
Maven spacecraft trajectory to Mars on Sept. 4, 2014. Credit: NASA

The $671 Million MAVEN spacecraft’s goal is to study Mars upper atmosphere to explore how the Red Planet lost most of its atmosphere and water over billions of years and the transition from its ancient, water-covered past, to the cold, dry, dusty world that it has become today.

MAVEN soared to space over nine months ago on Nov. 18, 2013 following a flawless blastoff from Cape Canaveral Air Force Station’s Space Launch Complex 41 atop a powerful Atlas V rocket and thus began a 10 month interplanetary voyage from Earth to the Red Planet.

It is streaking to Mars along with ISRO’s MOM orbiter, which arrives a few days later on September 24, 2014.

So far it has traveled 95% of the distance to the Red Planet, amounting to over 678,070,879 km (421,332,902 mi).

As of Sept. 4, MAVEN was 205,304,736 km (127,570,449 miles) from Earth and 4,705,429 km (2,923,818 mi) from Mars. Its Earth-centered velocity is 27.95 km/s (17.37 mi/s or 62,532 mph) and Sun-centered velocity is 22.29 km/s (13.58 mi/s or 48,892 mph) as it moves on its heliocentric arc around the Sun.

One-way light time from MAVEN to Earth is 11 minutes and 24 seconds.

MAVEN is NASA’s next Mars orbiter and launched on Nov. 18, 2014 from Cape Canaveral, Florida. It will study the evolution of the Red Planet’s atmosphere and climate. Universe Today visited MAVEN inside the clean room at the Kennedy Space Center. With solar panels unfurled, this is exactly how MAVEN looks when flying through space and circling Mars and observing Comet Siding Spring. Credit: Ken Kremer/kenkremer.com
MAVEN is NASA’s next Mars orbiter and launched on Nov. 18, 2014 from Cape Canaveral, Florida. It will study the evolution of the Red Planet’s atmosphere and climate. Universe Today visited MAVEN inside the clean room at the Kennedy Space Center. With solar panels unfurled, this is exactly how MAVEN looks when flying through space and circling Mars and observing Comet Siding Spring. Credit: Ken Kremer/kenkremer.com

Stay tuned here for Ken’s continuing MAVEN, MOM, Rosetta, Opportunity, Curiosity, Mars rover and more Earth and planetary science and human spaceflight news.

Ken Kremer

NASA’s Mars bound MAVEN spacecraft launches atop Atlas V booster at 1:28 p.m. EST from Space Launch Complex 41 at Cape Canaveral Air Force Station on Nov. 18, 2013. Image taken from the roof of the Vehicle Assembly Building (VAB) at NASA’s Kennedy Space Center.  Credit: Ken Kremer/kenkremer.com
NASA’s Mars bound MAVEN spacecraft launches atop Atlas V booster at 1:28 p.m. EST from Space Launch Complex 41 at Cape Canaveral Air Force Station on Nov. 18, 2013. Image taken from the roof of the Vehicle Assembly Building (VAB) at NASA’s Kennedy Space Center. Credit: Ken Kremer/kenkremer.com
NASA’s MAVEN Mars orbiter, chief scientist Prof. Bruce Jakosky of CU-Boulder and Ken Kremer of Universe Today inside the clean room at the Kennedy Space Center on Sept. 27, 2013. MAVEN launches to Mars on Nov. 18, 2013 from Florida. Credit: Ken Kremer/kenkremer.com
NASA’s MAVEN Mars orbiter, chief scientist Prof. Bruce Jakosky of CU-Boulder and Ken Kremer of Universe Today inside the clean room at the Kennedy Space Center on Sept. 27, 2013. MAVEN launched to Mars on Nov. 18, 2013 from Florida. Credit: Ken Kremer/kenkremer.com

Curiosity Celebrates Two Years on Mars Approaching Bedrock of Mountain Climbing Destination

2 Years on Mars!
Curiosity treks to Mount Sharp, her primary science destination, in this photo mosaic view captured on Sol 669, June 24, 2014. Navcam camera raw images stitched and colorized. Credit: NASA/JPL-Caltech/Marco Di Lorenzo/Ken Kremer – kenkremer.com
Story and mosaics updated[/caption]

NASA’s most scientifically powerful rover ever dispatched to the Red Planet, Curiosity, is celebrating her 2nd anniversary on Mars since the dramatic touchdown inside Gale Crater on Aug. 6, 2012, EDT (Aug. 5, 2012, PDT) while simultaneously approaching a bedrock unit that for the first time is actually part of the humongous mountain she will soon scale and is the primary science destination of the mission.

Mount Sharp is a layered mountain that dominates most of Gale Crater and towers 3.4 miles (5.5 kilometers) into the Martian sky and is taller than Mount Rainier.

Aug. 6, 2014 marks ‘2 Years on Mars’ and Sol 711 for Curiosity in an area called “Hidden Valley.”

“Getting to Mount Sharp is the next big step for Curiosity and we expect that in the Fall of this year,” Dr. Jim Green, NASA’s Director of Planetary Sciences at NASA Headquarters, Washington, DC, told me in an interview making the 2nd anniversary.

The 1 ton rover is equipped with 10 state-of-the-art science instruments and searching for signs of life.

The mysterious mountain is so huge that outcrops of bedrock extend several miles out from its base and Curiosity is now within striking distance of reaching the area the rover team calls “Pahrump Hills.”

2 Earth Years on Mars!  NASA’s Curiosity rover celebrated the 2nd anniversary on Mars at ‘Hidden Valley’ as shown in this photo mosaic view captured on Aug. 6, 2014, Sol 711.  Note the valley walls, rover tracks and distant crater rim. Navcam camera raw images stitched and colorized.  Credit: NASA/JPL-Caltech/Ken Kremer-kenkremer.com/Marco Di Lorenzo
2 Earth Years on Mars!
NASA’s Curiosity rover celebrated the 2nd anniversary on Mars at ‘Hidden Valley’ as shown in this photo mosaic view captured on Aug. 6, 2014, Sol 711. Note the valley walls, rover tracks and distant crater rim. Navcam camera raw images stitched and colorized. Credit: NASA/JPL-Caltech/Ken Kremer-kenkremer.com/Marco Di Lorenzo

Scientists anticipate that the outcrops at “Pahrump Hills” offer a preview of a geological unit that is part of the base of Mount Sharp for the first time since landing rather than still belonging to the floor of Gale Crater.

“We’re coming to our first taste of a geological unit that’s part of the base of the mountain rather than the floor of the crater,” said Curiosity Project Scientist John Grotzinger of the California Institute of Technology, Pasadena, in a statement.

“We will cross a major terrain boundary.”

Since “Pahrump Hills” is less than one-third of a mile (500 meters) from Curiosity she should arrive soon.

In late July 2014, the rover arrived in an area of sandy terrain called “Hidden Valley” which is on the planned route ahead leading to “Pahrump Hills” and easily traversable with few of the sharp edged rocks that have caused significant damage to the rovers six aluminum wheels.

This full-circle panorama of the landscape surrounding NASA's Curiosity Mars rover on July 31, 2014, Sol 705, offers a view into sandy lower terrain called "Hidden Valley," which is on the planned route ahead. It combines several images from Curiosity's Navigation Camera. South is at the center. Credit: NASA/JPL-Caltech
This full-circle panorama of the landscape surrounding NASA’s Curiosity Mars rover on July 31, 2014, Sol 705, offers a view into sandy lower terrain called “Hidden Valley,” which is on the planned route ahead. It combines several images from Curiosity’s Navigation Camera. South is at the center. Credit: NASA/JPL-Caltech

The sedimentary layers in the lower slopes of Mount Sharp have been Curiosity’s long-term science destination.

They are the principal reason why the science team specifically chose Gale Crater as the primary landing site based on high resolution spectral observations collected by NASA’s powerful Mars Reconnaissance Orbiter (MRO) indicating the presence of deposits of clay-bearing sedimentary rocks.

Curiosity’s goal all along has been to determine whether Mars ever offered environmental conditions favorable for microbial life. Finding clay bearing minerals. or phyllosilicates, in Martian rocks is the key to fulfilling its major objective.

The team expected to find the clay bearing minerals only in the sedimentary layers at the lower reaches of Mount Sharp.

Curiosity rover panorama of Mount Sharp captured on June 6, 2014 (Sol 651) during traverse inside Gale Crater.  Note rover wheel tracks at left.  She will eventually ascend the mountain at the ‘Murray Buttes’ at right later this year. Assembled from Mastcam color camera raw images and stitched by Marco Di Lorenzo and Ken Kremer.   Credit:   NASA/JPL/MSSS/Marco Di Lorenzo/Ken Kremer-kenkremer.com
Curiosity rover panorama of Mount Sharp captured on June 6, 2014 (Sol 651) during traverse inside Gale Crater. Note rover wheel tracks at left. She will eventually ascend the mountain at the ‘Murray Buttes’ at right later this year. Assembled from Mastcam color camera raw images and stitched by Marco Di Lorenzo and Ken Kremer. Credit: NASA/JPL/MSSS/Marco Di Lorenzo/Ken Kremer-kenkremer.com

Soon after landing, the team spotted some rather interesting looking outcrops barely a half mile away from the touchdown zone at a spot dubbed ‘Yellowknife Bay” and decided to take a detour towards it to investigate.

Well the scientists won the bet and struck scientific gold barely six months after landing when they drilled into a rock outcrop named “John Klein” at “Yellowknife Bay” and unexpectedly discovered the clay bearing minerals on the crater floor.

Yellowknife Bay was found to be an ancient lakebed where liquid water flowed on Mars surface billions of years ago.

The discovery of phyllosilicates in the 1st drill sample during the spring of 2013 meant that Curiosity had rather remarkably already fulfilled its primary goal of finding a habitable zone during its first year of operations!

The rock analysis “yielded evidence of a lakebed environment billions of years ago that offered fresh water, all of the key elemental ingredients for life, and a chemical source of energy for microbes, if any existed there,” according to NASA.

Curiosity accomplished Historic 1st drilling into Martian rock at John Klein outcrop on Feb 8, 2013 (Sol 182) and discovered a habitable zone, shown in this context mosaic view of the Yellowknife Bay basin taken on Jan. 26 (Sol 169). The robotic arm is pressing down on the surface at John Klein outcrop of veined hydrated minerals – dramatically back dropped with her ultimate destination; Mount Sharp. Credit: NASA/JPL-Caltech/Ken Kremer-kenkremer.com/Marco Di Lorenzo
Curiosity accomplished Historic 1st drilling into Martian rock at John Klein outcrop on Feb 8, 2013 (Sol 182) and discovered a habitable zone, shown in this context mosaic view of the Yellowknife Bay basin taken on Jan. 26 (Sol 169). The robotic arm is pressing down on the surface at John Klein outcrop of veined hydrated minerals – dramatically back dropped with her ultimate destination; Mount Sharp. Credit: NASA/JPL-Caltech/Ken Kremer-kenkremer.com/Marco Di Lorenzo

“Before landing, we expected that we would need to drive much farther before answering that habitability question,” said Curiosity Project Scientist John Grotzinger of the California Institute of Technology, Pasadena. “We were able to take advantage of landing very close to an ancient streambed and lake. Now we want to learn more about how environmental conditions on Mars evolved, and we know where to go to do that.”

During the rovers second Earth year on the Red Planet, Curiosity has been driving as fast as possible towards a safe entry point to the slopes of Mount Sharp. The desired destination for the car sized rover is now about 2 miles (3 kilometers) southwest of its current location.

‘Driving, Driving, Driving’
is indeed the rover teams mantra.

The main map here shows the assortment of landforms near the location of NASA's Curiosity Mars rover as the rover's second anniversary of landing on Mars nears. The gold traverse line entering from upper right ends at Curiosity's position as of Sol 705 on Mars (July 31, 2014). The inset map shows the mission's entire traverse from the landing on Aug. 5, 2012, PDT (Aug. 6, EDT) to Sol 705, and the remaining distance to long-term science destinations near Murray Buttes, at the base of Mount Sharp. The label "Aug. 5, 2013" indicates where Curiosity was one year after landing.    Credit: NASA/JPL-Caltech/Univ. of Arizona
The main map here shows the assortment of landforms near the location of NASA’s Curiosity Mars rover as the rover’s second anniversary of landing on Mars nears. The gold traverse line entering from upper right ends at Curiosity’s position as of Sol 705 on Mars (July 31, 2014). The inset map shows the mission’s entire traverse from the landing on Aug. 5, 2012, PDT (Aug. 6, EDT) to Sol 705, and the remaining distance to long-term science destinations near Murray Buttes, at the base of Mount Sharp. The label “Aug. 5, 2013” indicates where Curiosity was one year after landing. Credit: NASA/JPL-Caltech/Univ. of Arizona

To date, Curiosity’s odometer totals over 5.5 miles (9.0 kilometers) since landing inside Gale Crater on Mars in August 2012. She has taken over 174,000 images.

Curiosity still has about another 2 miles (3 kilometers) to go to reach the entry way at a gap in the treacherous sand dunes at the foothills of Mount Sharp sometime later this year.

And NASA is moving forward with future Red Planet missions when it recently announced the selection of 7 instruments chosen to fly aboard the Mars 2020 rover, the agency’s next rover going to Mars that will search for signs of ancient life as well as carry a technology demonstration that will help pave the way for ‘Humans to Mars’ in the 2030s. Read my story – here.

Coincidentally, ESA’s Rosetta comet hunting spacecraft arrived in orbit at its destination Comet 67P after a 10 year voyage on the same day as Curiosity’s 2 Earth year anniversary.

Stay tuned here for Ken’s continuing Rosetta, Curiosity, Opportunity, Orion, SpaceX, Boeing, Orbital Sciences, commercial space, MAVEN, MOM, Mars and more planetary and human spaceflight news.

Ken Kremer

Up close view of hole in one of rover Curiosity’s six wheels caused by recent driving over rough Martian rocks. Mosaic assembled from Mastcam raw images taken on Dec. 22, 2013 (Sol 490).  Credit: NASA/JPL/MSSS/Ken Kremer - kenkremer.com/Marco Di Lorenzo
Up close view of hole in one of rover Curiosity’s six wheels caused by recent driving over rough Martian rocks. Mosaic assembled from Mastcam raw images taken on Dec. 22, 2013 (Sol 490). Credit: NASA/JPL/MSSS/Ken Kremer – kenkremer.com/Marco Di Lorenzo

NASA Preps for Nail-biting Comet Flyby of Mars

As Comet C/2013 A1 Siding Spring inches closer to the Red Planet, NASA’s taking steps to protect its fleet of orbiting Mars spacecraft. On October 19, the comet’s icy nucleus will miss the planet by just 82,000 miles (132,000 km). That’s 17 times closer than the closest recorded Earth-approaching comet, Lexell’s Comet in 1770. 

Comet C/2013 A1 (Siding Spring) on July 11, 2014. The comet, discovered by comet hunter Rob McNaught from Siding Spring Observatory in New South Wales, Australia on January 3, 2013, shows a bright coma and well-developed tail. Credit: Joseph Brimacombe
Comet C/2013 A1 (Siding Spring) on July 11, 2014. The comet, discovered by comet hunter Robert McNaught from Siding Spring Observatory in New South Wales, Australia on January 3, 2013, shows a bright coma and well-developed tail. Credit: Joseph Brimacombe

No one’s worried about the tiny nucleus doing any damage. It’ll zip right by. Rather it’s dust particles embedded in vaporizing ice that concern NASA planners. Dust spreads into a broad tail that could potentially brush Mars’ upper atmosphere and strike an orbiter. A single particle of debris half a millimeter across may not seem like your mortal enemy, but when it’s traveling at 35 miles (56 km) per second relative to the spacecraft, one hit could spell trouble.

This graphic depicts the orbit of comet C/2013 A1 Siding Spring as it swings around the sun in 2014. On Oct. 19, the comet will have a very close pass at Mars. Its nucleus will miss Mars by about 82,000 miles (132,000 kilometers). The comet's trail of dust particles shed by the nucleus might be wide enough to reach Mars or might also miss it. Credit: NASA/JPL
The orbit of comet C/2013 A1 Siding Spring as it swings around the sun in 2014. NASA’s already begun moving the Mars orbiters toward safe positions in preparation for the upcoming flyby. Credit: NASA/JPL

“Three expert teams have modeled this comet for NASA and provided forecasts for its flyby of Mars,” explained Rich Zurek, chief scientist for the Mars Exploration Program at NASA’s Jet Propulsion Laboratory in Pasadena, California. “The hazard is not an impact of the comet nucleus, but the trail of debris coming from it. Using constraints provided by Earth-based observations, the modeling results indicate that the hazard is not as great as first anticipated. Mars will be right at the edge of the debris cloud, so it might encounter some of the particles — or it might not.”

The agency’s taking a prudent approach. NASA currently operates the Mars Reconnaissance Orbiter (MRO) and Mars Odyssey spacecraft with a third orbiter, MAVEN, currently on its way to the planet and expected to settle into orbit a month before the comet flyby. Teams operating the orbiters plan to have all spacecraft positioned on the opposite side of Mars when the comet is most likely to pass by.

Already, mission planners tweaked MRO’s orbit on July 2 to move it toward a safe position with a second maneuver to follow on August 27. A similar adjustment is planned for Mars Odyssey on August 5 and October 9 for the Mars Atmosphere and Volatile Evolution (MAVEN) probe. The time of greatest risk to the spacecraft is brief – about 20 minutes – when the widest part of the comet’s tail passes closest to the planet.

Will dust shed by the comet streak as meteors in the Martian sky on October 19?  The rovers will be watching. Credit: NASA/JPL
Will dust shed by the comet streak as meteors in the Martian sky on October 19? The rovers will be watching. Credit: NASA/JPL

One question I’m always asked is whether the Mars rovers are in any danger of dust-producing meteors in the comet’s wake. While the planet might get peppered with a meteor shower, its atmosphere is thick enough to incinerate cometary dust particles before they reach the surface, not unlike what happens during a typical meteor shower here on Earth. Rover cameras may be used to photograph the comet before the flyby and to capture meteors during the comet’s closest approach.

Despite concerns about dust, NASA knows a good opportunity when it sees one. In the days before and after the flyby, all three orbiters will conduct studies on the comet.

According to a recent NASA press release, instruments on MRO and Odyssey will examine the nucleus, coma and tail and possible effects on the Martian atmosphere:

Comet Siding Spring observed by the Spitzer Space Telescope in two wavelengths of infrared light in March 2014. The hint of blue-white corresponds to dust, red-orange to gas. Credit: NASA
Comet Siding Spring observed by the Spitzer Space Telescope in two wavelengths of infrared light in March 2014. The hint of blue-white corresponds to dust, red-orange to gas. Credit: NASA/JPL-Caltech/M. Kelley (Univ. Maryland)

“Odyssey will study thermal and spectral properties of the comet’s coma and tail. MRO will monitor Mars’ atmosphere for possible temperature increases and cloud formation, as well as changes in electron density at high altitudes and MAVEN will study gases coming off the comet’s nucleus as it’s warmed by the sun. The team anticipates this event will yield detailed views of the comet’s nucleus and potentially reveal its rotation rate and surface features.”

This is Comet Siding Spring’s first trip to the inner solar system. Expect exciting news as we peer up close at pristine ices and dust that have been locked in deep freeze since the time the planets formed.

For more information on the event, check out this NASA website devoted to the comet.

 

 

 

Curiosity Captured from Orbit Crossing Landing Ellipse Boundary – Martian Scenery from Above and Below

NASA has now released a breathtaking high resolution image of the rover Curiosity captured from Mars orbit coincidentally coinciding with her crossing the targeted landing ellipse just days after she marked ‘1 Martian Year’ on the Red Planet in search of the chemical ingredients necessary to support alien microbial life forms.

The orbital image was taken on June 27 (Sol 672) by the High Resolution Imaging Science Experiment (HiRISE) camera on NASA’s Mars Reconnaissance Orbiter (MRO) and clearly shows the rover and wheel tracks at the end of the drive that Sol, or Martian day.

You can simultaneously experience the Martian eye view of Curiosity from above and below by checking out our Sol 672 ground level photo mosaic – below. It’s assembled from raw images taken by the mast mounted navigation camera (Navcam) showing the rovers wheel tracks and distant rim of the Gale Crater landing site.

Curiosity treks across Martian dunes and drives outside landing ellipse here, in this photo mosaic view captured on Sol 672, June 27, 2014.    Navcam camera raw images stitched and colorized.   Credit: NASA/JPL-Caltech/Marco Di Lorenzo/Ken Kremer – kenkremer.com
Curiosity treks across Martian dunes and drives outside landing ellipse here, in this photo mosaic view captured on Sol 672, June 27, 2014. Navcam camera raw images stitched and colorized. Credit: NASA/JPL-Caltech/Marco Di Lorenzo/Ken Kremer – kenkremer.com

The six wheeled robot drove about 269 feet (82 meters) on June 27 traversing to the boundary of her targeted landing ellipse in safe terrain – approximately 4 miles wide and 12 miles long (7 kilometers by 20 kilometers) – for the first time since touchdown on Mars nearly two years ago on August 5, 2012 inside Gale Crater.

Curiosity celebrated another Martian milestone anniversary on June 24 (Sol 669) – 1 Martian Year on Mars!

A Martian year is equivalent to 687 Earth days, or nearly two Earth years.

1 Martian Year on Mars!  Curiosity treks to Mount Sharp in this photo mosaic view captured on Sol 669, June 24, 2014.    Navcam camera raw images stitched and colorized.   Credit: NASA/JPL-Caltech/Marco Di Lorenzo/Ken Kremer – kenkremer.com
1 Martian Year on Mars!
Curiosity treks to Mount Sharp in this photo mosaic view captured on Sol 669, June 24, 2014. Navcam camera raw images stitched and colorized. Credit: NASA/JPL-Caltech/Marco Di Lorenzo/Ken Kremer – kenkremer.com

The SUZ sized rover is driving as swiftly as possible to the base of Mount Sharp which dominates the center of Gale Crater and reaches 3.4 miles (5.5 km) into the Martian sky – taller than Mount Rainier.

During Year 1 on Mars, Earth’s emissary has already accomplished her primary objective of discovering a habitable zone on the Red Planet that contains the minerals necessary to support microbial life in the ancient past when Mars was far wetter and warmer billions of years ago.

To date, Curiosity’s odometer totals over 5.1 miles (8.4 kilometers) since landing inside Gale Crater on Mars in August 2012. She has taken over 165,000 images.

Curiosity still has about another 2.4 miles (3.9 kilometers) to go to reach the entry way at a gap in the treacherous sand dunes at the foothills of Mount Sharp sometime later this year.

Stay tuned here for Ken’s continuing Curiosity, Opportunity, Orion, SpaceX, Boeing, Orbital Sciences, commercial space, MAVEN, MOM, Mars and more planetary and human spaceflight news.

Ken Kremer

Are These Water Flows On Mars? Quite Possibly, New Observations Reveal

What a tangled web of water and water ice stories on Mars. There’s likely some underground. There’s definitely some at the north pole. And we are pretty certain water flowed there in the ancient past. But what about surface water today, right now, in the view of our many orbiting cameras at the Red Planet?

One hotspot of debate are flows called “recurring slope lineae”, which are features that appear in warmer temperatures. These would seem to imply some kind of briny water flowing. A team recently checked out 13 of these sites. While they didn’t find any water or salt evidence in the spectra, they did find more iron-bearing minerals on “RSL slopes” compared to those that aren’t. So what’s going on?

“We still don’t have a smoking gun for existence of water in RSL, although we’re not sure how this process would take place without water,” stated Lujendra Ojha, a graduate student at the Georgia Institute of Technology in Atlanta who led two reports on these features. Pictures were taken using NASA’s Mars Reconnaissance Orbiter’s High Resolution Imaging Science Experiment (HiRISE), which is led by the University of Arizona.

Palikir Crater as seen by the Mars Reconnaissance Orbiter's High Resolution Imaging Science Experiment (HiRISE) camera. Visible are warm-season flows called "recurring slope linea" that could have been created by salty liquid water. Credit: NASA/JPL-Caltech/UA/JHU-APL
Palikir Crater as seen by the Mars Reconnaissance Orbiter’s High Resolution Imaging Science Experiment (HiRISE) camera. Visible are warm-season flows called “recurring slope linea” that could have been created by salty liquid water. Credit: NASA/JPL-Caltech/UA/JHU-APL

It’s possible that the grains are being sorted by size (more plainly speaking, taking the fine dust away and leaving the larger grains behind), which could happen either with water or without it. Or, water might be present but not in a way that is obvious immediately if the area got darker because of moisture, or the minerals became oxidized. Water could be “missing” from these observations because they took place in the afternoon (meaning they could miss morning dew), or because the dark flows are smaller than the sample size in the picture.

While researchers still aren’t sure, the team says they still believe it’s salty water of some sort that is flowing despite very cold temperatures on Mars.

“The flow of water, even briny water, anywhere on Mars today would be a major discovery, impacting our understanding of present climate change on Mars and possibly indicating potential habitats for life near the surface on modern Mars,” said Richard Zurek, MRO project scientist who is at NASA’s Jet Propulsion Laboratory in California.

A related paper also found that RSL sites are rare on Mars, appearing in only 13 of 200 sites surveyed with similar slopes, latitudes and other features. You can read the accepted versions of the reports as they appear in Geophysical Research Letters and Icarus.

Skim Across Mars In Virtual Reality With These New Orbital Images

Stop what you’re doing, grab the nearest 3-D glasses (red/blue type) you have available and then pretend you’re hovering above Mars for a while. These are some of the latest images from the Mars Reconnaissance Orbiter, which has been cruising above the planet since 2006.

Make sure to click through these pictures to see the full, raw files from the University of Arizona’s High Resolution Imaging Science Experiment (HiRISE) web page. HiRISE was the imager that took these pictures. Enjoy!

"Candidate Future Landing Site at Valley North of Jezero Crater", imaged by the Mars Reconnaissance Orbiter's HiRISE (High Resolution Imaging Science Experiment). Credit: NASA/JPL/University of Arizona
“Candidate Future Landing Site at Valley North of Jezero Crater”, imaged by the Mars Reconnaissance Orbiter’s HiRISE (High Resolution Imaging Science Experiment). Credit: NASA/JPL/University of Arizona
"Fossae Source of Outflows," a picture taken by Mars Reconnaissance Orbiter's HiRISE (High Resolution Imaging Science Experiment). Credit: NASA/JPL/University of Arizona
“Fossae Source of Outflows,” a picture taken by Mars Reconnaissance Orbiter’s HiRISE (High Resolution Imaging Science Experiment). Credit: NASA/JPL/University of Arizona
"Floor of East Candor Chasma," a picture taken by the Mars Reconnaissance Orbiter's HiRISE (High Resolution Imaging Science Experiment). Credit: NASA/JPL/University of Arizona
“Floor of East Candor Chasma,” a picture taken by the Mars Reconnaissance Orbiter’s HiRISE (High Resolution Imaging Science Experiment). Credit: NASA/JPL/University of Arizona
"Knobs with bright layers in Noctis Labyrinthus", a picture taken by the Mars Reconnaissance Orbiter's HiRISE (High Resolution Imaging Science Experiment). Credit: NASA/JPL/University of Arizona
“Knobs with bright layers in Noctis Labyrinthus”, a picture taken by the Mars Reconnaissance Orbiter’s HiRISE (High Resolution Imaging Science Experiment). Credit: NASA/JPL/University of Arizona

A Dark and Dusty Avalanche on Mars

Mars may be geologically inactive but that doesn’t mean there’s nothing happening there — seasonal changes on the Red Planet can have some very dramatic effects on the landscape, as this recent image from the HiRISE camera shows!

The full extent of the 1000-meter-long dusty landslide (NASA/JPL/University of Arizona)
The full extent of the 1000-meter-long dusty landslide (NASA/JPL/University of Arizona)

When increasing light from the springtime Sun warms up the sides of sheer cliffs made from countless layers of water and carbon dioxide ice near Mars’ north pole, some of that CO2 ice sublimes, sending cascades of loose soil and dust down to the terraced base below. This uncovered material stains the frost-covered polar surface dark, outlining the paths of avalanches for HiRISE to easily spot from orbit. (See the original HiRISE image here.)

Circling Mars since March 2006, the HiRISE camera aboard NASA’s Mars Reconnaissance Orbiter has even captured some of these polar landslides in action.

The rust-colored avalanche shown above has fallen hundreds of meters from the middle of a layered ice deposit, spreading nearly a kilometer across the frozen ridges at the base of the cliff. The view was acquired on Sept. 13, 2013.

Check out a video explaining this view and the processes that created it below, narrated by Phil Plait (aka the Bad Astronomer).

Mars’ seasonal polar caps are composed primarily of carbon dioxide frost. This frost sublimates (changes from solid directly to gas) in the spring, boosting the pressure of Mars’ thin atmosphere. In the fall the carbon dioxide condenses, causing the polar caps to reach as far as ~55 degrees latitude by late winter. By learning about current processes on a local level we can learn more about how to interpret the geological record of climate changes on Mars. (Source)

This is Comet ISON Seen From Mars

It’s not much to look at, but there it is: the incoming comet ISON (aka C/2012 S1) as seen by the HiRISE camera aboard NASA’s Mars Reconnaissance Orbiter. An enlarged version of one of four just-released images, this represents a 256-by-256-pixel patch of sky imaged by HiRISE on Sunday, September 29. ISON is the fuzzy blob at center, 8.5 million miles (13.8 million km) away.

See all four images below:

HiRISE images of ISON on Sept. 29, 2013 (NASA/JPL/University of Arizona)
HiRISE images of ISON on Sept. 29, 2013 (NASA/JPL/University of Arizona)

HiRISE researchers Alan Delamere and Alfred McEwen explained in a news release:

Based on preliminary analysis of the data, the comet appears to be at the low end of the range of brightness predictions for the observation. As a result, the image isn’t visually pleasing but low coma activity is best for constraining the size of the nucleus. This image has a scale of approximately 8 miles (13.3 km) per pixel, larger than the comet, but the size of the nucleus can be estimated based on the typical brightness of other comet nuclei. The comet, like Mars, is currently 241 million kilometers from the Sun. As the comet gets closer to the sun, its brightness will increase to Earth-based observers and the comet may also become intrinsically brighter as the stronger sunlight volatilizes the comet’s ices.

More images of ISON from HiRISE are expected as the comet came even closer to Mars, approaching within 6.7 million miles (10.8 million km), but the illumination from those angles may not be as good.

NOTE: These are preliminary single (non-stacked) images, and still contain noise and background stars – hence the fuzziness. Plus HiRISE was not really designed for sky imaging! (Thanks to HiRISE team member Kristin Block for the info.)

So even though it’s at the “low end” of brightness predictions in these HiRISE images, ISON certainly hasn’t “fizzled” like some reports claimed earlier this year (although just how bright it will get in our skies remains to be seen.)

Comet ISON will make its closest pass of the Sun (perihelion) on November 28, 2013, coming within 724,000 miles (1.16 million km) before heading back out into the Solar System… if it survives the encounter, that is. Read more about how to view ISON here and here.

Source: University of Arizona HiRISE article by Alan Delamere and Alfred McEwen

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Worried about ISON’s first (and possibly last) visit to the inner Solar System? Don’t be. Recent rumors of comet-caused catastrophe are greatly exaggerated… read more on David Dickinson’s article Debunking Comet ISON Conspiracy Theories (No, ISON is Not Nibiru).

Feast Your Mind on This: Strange “Brain Terrain” on Mars

It doesn’t take much thought to understand why this landscape on Mars is called “brain terrain” — the swirling lobes of ice, part of a large glacial deposit in Mars’ northern hemisphere, uncannily resemble the texture of a brain — or at the very least a brain coral!

What causes this strange landscape? Find out below:

It’s suggested that brain terrain is the result of the thermal stress and contraction, followed by sublimation, of these large ice deposits, laid down during a mid-latitude glaciation period ten to 100 million years ago. (Read more in this 2009 paper by Brown University’s Joseph Levy et al.)

This image was obtained by the HiRISE camera aboard the Mars Reconnaissance orbiter on August 23, 2013. See the original RGB color scan here.

Source: University of Arizona’s HiRISE site