Ancient comets may have created Titan's nitrogen-rich atmosphere
[/caption]
Titan is a fascinating world to planetary scientists. Although it’s a moon of Saturn it boasts an opaque atmosphere ten times thicker than Earth’s and a hydrologic cycle similar to our own – except with frigid liquid methane as the key component instead of water. Titan has even been called a living model of early Earth, even insofar as containing large amounts of nitrogen in its atmosphere much like our own. Scientists have wondered at the source of Titan’s nitrogen-rich atmosphere, and now a team at the University of Tokyo has offered up an intriguing answer: it may have come from comets.
Traditional models have assumed that Titan’s atmosphere was created by volcanic activity or the effect of solar UV radiation. But these rely on Titan having been much warmer in the past than it is now…a scenario that Cassini mission scientists don’t think is the case.
New research suggests that comet impacts during a period called the Late Heavy Bombardment – a time nearly 4 billion years ago when collisions by large bodies such as comets and asteroids were occurring regularly among worlds in our solar system – may have generated Titan’s nitrogen atmosphere. By firing lasers into ammonia-and-water-ice material similar to what would have been found on primordial Titan, researchers saw that nitrogen was a typical result. Over the millennia these impacts could have created enough nitrogen to cover the moon in a dense haze, forming the thick atmosphere we see today.
“We propose that Titan’s nitrogen atmosphere formed after accretion, by the conversion from ammonia that was already present on Titan during the period of late heavy bombardment about four billion years ago.”
– Yasuhito Sekine et al., University of Tokyo, Japan
This model, if true, would also mean that the source of Titan’s nitrogen would be different than that of other outer worlds, like Pluto, and even inner planets like our own.
Top image is a combination of a color-composite of Titan made from raw Cassini data taken on October 12, 2010 and a recolored infrared image of the comet Siding Spring, taken by NASA’s WISE observatory on January 10, 2010. The background stars were also taken by the Cassini orbiter. NASA / JPL / SSI and Caltech/UCLA. Edited by J. Major.
Note: the image at top is not scientifically accurate…the comet’s tail would be, based on the lighting of Titan, pointing more to the ten o’clock position as well as forward toward the viewer’s left shoulder. This would make it ‘look’ as if it were going the opposite direction though, away from Titan, and so I went with the more immediately decipherable version seen here. To see a more “realistic” version, click here.
Pitted "swiss cheese" terrain at Mars' south pole hints at sublimation of underground CO2
[/caption]
Scientists have spotted an underground reservoir near Mars’ south pole the size of Lake Superior… except that this lake is filled with frozen carbon dioxide – a.k.a. “dry ice”!
A recent report by scientists at the Southwest Research Institute in Boulder, CO reveals variations in Mars’ axial tilt can change how much carbon dioxide gets released into the atmosphere, affecting factors from the stability of water on its surface to the power and frequency of dust storms.
Thickness Map of Buried CO2 Ice Deposit
The Mars Reconnaissance Orbiter’s ground-penetrating Shallow Radar identified a subsurface deposit of frozen material, confirmed as carbon dioxide ice by its radar signature and visual correlation to the surface pitting seen above. As the polar surface warms during the Martian spring, underground CO2 deposits evaporate (or “sublime”) leaving behind round depressions in the frozen ground. (This has been aptly dubbed “swiss cheese terrain” by researchers on the HiRISE imaging team.)
While scientists were aware of seasonal CO2 ice layers atop the water ice this new discovery brings to light nearly 30 times more frozen CO2 than was previously believed to exist. In fact this particular deposit alone contains 80% the amount of CO2 currently present in the planet’s entire atmosphere.
The importance of this finding is how the carbon dioxide ultimately affects the global Martian climate as it freezes and thaws. When the CO2 is frozen and locked away in subsurface deposits like this, it’s not free to enter the atmosphere and do what CO2 does best: warm the planet… as well as increase atmospheric pressure. This means that liquid water cannot last as readily on the surface since it will either freeze or boil away. Also with less air pressure the strength of wind is decreased, so dust storms are less frequent and less severe.
When factored in with the axial tilt difference – and thus variations in the amount of sunlight hitting the poles – researchers’ models show that Mars’ average atmospheric pressure may at times be 75% higher than it is today.
These shifts in the orientation of the Red Planet’s axis occur on 100,000-year intervals… long by human standards but geologically very frequent. Mars may have had liquid water existing on its surface fairly recently!
Mars' south polar ice cap, seen in April 2000 by Mars Odyssey. NASA/JPL/MSSS
Although this may sound that Mars has had its own share of global warming due to CO2 emissions in its history, it must be remembered that Mars and Earth have very different atmospheric compositions. Earth’s atmosphere is much thicker and denser than Mars’, so even when doubling its CO2 content Mars’ atmosphere is still too thin and dry to create a strong greenhouse effect… especially considering that the polar caps on Mars increase cooling more than additional CO2 in the atmosphere raises global temperature. Without oceans and atmosphere to collect and distribute heat, the effect of any warming quickly radiates out into space…and eventually the planet swings back into a freeze-dried state.
“Unlike Earth, which has a thick, moist atmosphere that produces a strong greenhouse effect, Mars’ atmosphere is too thin and dry to produce as strong a greenhouse effect as Earth’s, even when you double its carbon-dioxide content.”
– Robert Haberle, planetary scientist at NASA’s Ames Research Center
Artist's illustration of Pluto's surface. Credit: NASA
[/caption]
Ah, Pluto. Seems every time we think we’ve got it figured out, it has a new surprise to throw at us.
First spotted in 1930 by a young Clyde Tombaugh, for 76 years it enjoyed a comfortable position as the solar system’s most distant planet. Then a controversial decision in 2006 by the International Astronomical Union, spurred by suggestions from astronomer (and self-confessed “planet-killer”) Mike Brown*, relegated Pluto to a new class of worlds called “dwarf planets”. Not quite planets and not quite asteroids, dwarf planets cannot entirely clear their orbital path with their own gravitational force and thus miss out on full planetary status. Besides immediately making a lot of science textbooks obsolete and rendering the handy mnemonic “My Very Eager Mother Just Served Us Nine Pies” irrelevant (or at least confusing), the decision angered many people around the world, both in and out of the scientific community. Pluto is a planet, they said, it always has been and always will be! Save Pluto! the schoolkids wrote in crayon to planetarium directors. The world all of a sudden realized how much people liked having Pluto as the “last” planet, and didn’t want to see it demoted by decision, especially a highly contested one.
Yet as it turns out, Pluto really may not be a planet after all.
It may be a comet.
But…that’s getting ahead of ourselves. First things first.
Discovery data showing carbon monoxide spectrum. Credit: J.S. Greaves / Joint Astronomy Centre.
Recent discoveries by a UK team of astronomers points to the presence of carbon monoxide in Pluto’s atmosphere. Yes, Pluto has an atmosphere; astronomers have known about it since 1988. At first assumed to be about 100km thick, it was later estimated to extend out about 1500km and be composed of methane gas and nitrogen. This gas would expand from the planet’s – er, dwarf planet’s – surface as it came closer to the Sun during the course of its eccentric 248-year orbit and then freeze back onto the surface as it moved further away. The new findings from the University of St Andrews team, made by observations with the James Clerk Maxwell telescope in Hawaii, identify an even thicker atmosphere containing carbon monoxide that extends over 3000 km, reaching nearly halfway to Pluto’s largest moon, Charon.
It’s possible that this carbon monoxide atmosphere may have expanded outwards from Pluto, especially in the years since 1989 when it made the closest approach to the Sun in its orbit. Surface heating (and the term “heating” is used scientifically here…remember, at around -240ºC (-400ºF) Pluto would seem anything but balmy to us!) by the Sun’s radiation would have warmed the surface and expelled these gases outwards. This also coincides with observations made by the Hubble Space Telescope over the course of four years, which revealed varying patterns of dark and light areas on Pluto’s surface – possibly caused by the thawing of frozen areas that shift and reveal lighter surface material below.
“Seeing such an example of extra-terrestrial climate-change is fascinating. This cold simple atmosphere that is strongly driven by the heat from the Sun could give us important clues to how some of the basic physics works, and act as a contrasting test-bed to help us better understand the Earth’s atmosphere.”
– Dr. Jane Greaves, Team Leader
In fact, carbon monoxide may be the key to why Pluto even still has an atmosphere. Unlike methane, which is a greenhouse gas, carbon monoxide acts as a coolant; it may be keeping Pluto’s fragile atmosphere from heating up too much and escaping into space entirely! Over the decades and centuries that it takes for Pluto to complete a single year, the balance between these two gases must be extremely precise.
So here we have Pluto exhibiting an expanding atmosphere of thawing expelled gas as it gets closer to the Sun in an elliptical, eccentric orbit. (Sound familiar?) And now there’s another unusual, un-planet-like feature that’s being put on the table: Pluto may have a tail.
Actually this is an elaboration of the research results coming from the same team at the University of St Andrews. The additional element here is a tiny redshift detected in the carbon monoxide signature, indicating that it is moving away from us in an unusual way. It’s possible that this could be caused by the top layers of Pluto’s atmosphere – where the carbon monoxide resides – being blown back by the solar wind into, literally, a tail.
That sounds an awful lot, to this particular astronomy reporter anyway, like a comet.
Just saying.
Anyway, regardless of what Pluto is or isn’t, will be called or used to be called, there’s no denying that it is a fascinating little world that deserves our attention. (And it will be getting plenty of that come July 2015 when the New Horizons spacecraft swings by for a visit!) I’m sure there’s no one here who would argue that fact.
New Horizons’ upcoming visit will surely answer many questions about Pluto – whatever it is – and most likely raise even more.
Artist's impression of Pluto's huge atmosphere of carbon monoxide.Credit:P.A.S. Cruickshank.
The new discovery was presented by team leader Dr. Jane Greaves on Wednesday, April 20 at the National Astronomy Meeting in Wales.
Article reference: arxiv.org/abs/1104.3014: Discovery Of Carbon Monoxide In The Upper Atmosphere Of Pluto
*No disrespect to Mr. Brown intended…he was just performing science as he saw fit!
[/caption]
Solar disruption theory was one of several theories that emerged before the 18th century concerning the formation of the solar system. Solar disruption theory states that the collision of the sun with another stars caused debris to be ejected from its mass and these debris eventually became the planets. This theory was later discarded for the nebula theory of solar system formation. However there are some scientists that propose that it has some merit.
The big question up until the 18th century was how the solar system was born. There were many explanations for why this happen but many were really only conjecture given the tools available to astronomers at the time. The real question was what would be a probable origin under the known laws of physics. The advent of classical mechanics came to prove the nebular theory as the likely theory for the creation of the solar system. The reason was that most other theories could not explain how the planets formed without giving in to the Sun’s gravity and falling in.
A new argument has emerged for a different form of solar disruption theory in this version it answers the idea in a more roundabout way that answers an interesting question. We know that the formation of the solar system itself was volatile but did the Sun and its planets really form in relative isolation from other star emerging in the Nebula? This new theory that emerged in 2004 supposed proposed that the influence of other stars may have influenced the formation of planets in the solar system.
In the meanwhile the main theory stands. We know in the nebular theory that stars are formed from spinning nebulas of gases and cosmic dust. Over time the masses clump together to the point where the mass reaches the level needed for gravity to initiate fusion. The planets are formed from the clumps of debris in the nebular disk that did not fall into the Sun and that they eventually ended up colliding with each other forming planets. Any theory that suggests interference from the gravity fields of other star systems has not been tested yet. It may have merit but we don’t have the technology to test theories on such large scales.
The Juno spacecraft passes in front of Jupiter in this artist's depiction. Juno, the second mission in NASA's New Frontiers program, will improve our understanding of the solar system by advancing studies of the origin and evolution of Jupiter. The spacecraft will carry eight instruments to investigate the existence of a solid planetary core, map Jupiter's intense magnetic field, measure the amount of water and ammonia in the deep atmosphere, and observe the planet's auroras. Credit: NASA/JPL-Caltech
[/caption]
Juno, NASA’s next big mission bound for the outer planets, has arrived at the Kennedy Space Center to kick off the final leg of launch preparations in anticipation of blastoff for Jupiter this summer.
The huge solar-powered Juno spacecraft will skim to within 4800 kilometers (3000 miles) of the cloud tops of Jupiter to study the origin and evolution of our solar system’s largest planet. Understanding the mechanism of how Jupiter formed will lead to a better understanding of the origin of planetary systems around other stars throughout our galaxy.
Juno will be spinning like a windmill as it fly’s in a highly elliptical polar orbit and investigates the gas giant’s origins, structure, atmosphere and magnetosphere with a suite of nine science instruments.
Technicians at Astrotech's payload processing facility in Titusville, Fla. secure NASA's Juno spacecraft to the rotation stand for testing. The solar-powered spacecraft will orbit Jupiter's poles 33 times to find out more about the gas giant's origins. Credit: NASA/Jack Pfaller
During the five year cruise to Jupiter, the 3,600 kilogram probe will fly by Earth once in 2013 to pick up speed and accelerate Juno past the asteroid belt on its long journey to the Jovian system where it arrives in July 2016.
Juno will orbit Jupiter 33 times and search for the existence of a solid planetary core, map Jupiter’s intense magnetic field, measure the amount of water and ammonia in the deep atmosphere, and observe the planet’s auroras.
The mission will provide the first detailed glimpse of Jupiter’s poles and is set to last approximately one year. The elliptical orbit will allow Juno to avoid most of Jupiter’s harsh radiation regions that can severely damage the spacecraft systems.
Juno was designed and built by Lockheed Martin Space Systems, Denver, and air shipped in a protective shipping container inside the belly of a U.S. Air Force C-17 Globemaster cargo jet to the Astrotech payload processing facility in Titusville, Fla.
Juno undergoes acoustics testing at Lockheed Martin in Denver where the spacecraft was built. Credit: NASA/JPL-Caltech/Lockheed Martin
This week the spacecraft begins about four months of final functional testing and integration inside the climate controlled clean room and undergoes a thorough verification that all its systems are healthy. Other processing work before launch includes attachment of the long magnetometer boom and solar arrays which arrived earlier.
Juno is the first solar powered probe to be launched to the outer planets and operate at such a great distance from the sun. Since Jupiter receives 25 times less sunlight than Earth, Juno will carry three giant solar panels, each spanning more than 20 meters (66 feet) in length. They will remain continuously in sunlight from the time they are unfurled after launch through the end of the mission.
“The Juno spacecraft and the team have come a long way since this project was first conceived in 2003,” said Scott Bolton, Juno’s principal investigator, based at Southwest Research Institute in San Antonio, in a statement. “We’re only a few months away from a mission of discovery that could very well rewrite the books on not only how Jupiter was born, but how our solar system came into being.”
Juno is slated to launch aboard the most powerful version of the Atlas V rocket – augmented by 5 solid rocket boosters – from Cape Canaveral, Fla. on August 5. The launch window extends through August 26. Juno is the second mission in NASA’s New Frontiers program.
NASA’s Mars Curiosity Rover will follow Juno to the Atlas launch pad, and is scheduled to liftoff in late November 2011. Read my stories about Curiosity here and here.
Because of cuts to NASA’s budget by politicians in Washington, the long hoped for mission to investigate the Jovian moon Europa may be axed, along with other high priority science missions. Europa may harbor subsurface oceans of liquid water and is a prime target in NASA’s search for life beyond Earth.
Technicians inside the clean room at Astrotech in Titusville, Fla. guide NASA's Juno spacecraft, as it is lowered by overhead crane, onto the rotation stand for testing. Credit: NASA/Jack PfallerTechnicians at Astrotech unfurl solar array No. 1 with a magnetometer boom that will help power NASA's Juno spacecraft on a mission to Jupiter. Credit: NASAJuno's interplanetary trajectory to Jupiter. Juno will launch in August 2011 and fly by Earth once in October 2013 during its 5 year cruise to Jupiter. Click to enlarge. Credit: NASA/JPL
Artist impression of Voyager 1, the first probe to traverse the heliosheath (NASA)
[/caption]
She might be old, but she’s still got it where it counts. The 33-year old Voyager 1 probe, flying out near the edge of the solar system conducted a roll program, spinning 70 degrees counterclockwise, and held the position by spinning gyroscopes for two hours, 33 minutes. Voyager performed its in-flight gymnastics on March 7, 2011 and scientists hope the maneuver will help answer the question of which direction is the sun’s stream of charged particles turns when it nears the edge of the solar system.
“Even though Voyager 1 has been traveling through the solar system for 33 years, it is still a limber enough gymnast to do acrobatics we haven’t asked it to do in 21 years,” said Suzanne Dodd, Voyager project manager, based at NASA’s Jet Propulsion Laboratory. “It executed the maneuver without a hitch, and we look forward to doing it a few more times to allow the scientists to gather the data they need.”
Voyager needed to get in the right orientation to enable its Low Energy Charged Particle instrument to gather data.
The last time either of the two Voyager spacecraft rolled and stopped in a gyro-controlled orientation was Feb. 14, 1990, when Voyager 1 snapped a family portrait of the planets. See the image here.
The two Voyager spacecraft are traveling through a turbulent area known as the heliosheath,the outer shell of a bubble around our solar system created by the solar wind. The solar wind is traveling outward from the sun at a million miles per hour. Scientists think the wind must turn as it approaches the heliosheath where it makes contact with the interstellar wind — , which originates in the region between stars.
In June 2010, when Voyager 1 was about 17 billion kilometers (about 11 billion miles) away from the sun, data from the Low Energy Charged Particle instrument began to show that the net outward flow of the solar wind was zero. That zero reading has continued since. The Voyager science team doesn’t think the wind has disappeared in that area, but perhaps has just turned a corner. But where does it go from there: up, down or to the side?
“Because the direction of the solar wind has changed and its radial speed has dropped to zero, we have to change the orientation of Voyager 1 so the Low Energy Charged Particle instrument can act like a kind of weather vane to see which way the wind is now blowing,” said Edward Stone, Voyager project manager. “Knowing the strength and direction of the wind is critical to understanding the shape of our solar bubble and estimating how much farther it is to the edge of interstellar space.”
Voyager engineers performed a test roll and hold back on Feb. 2, just to make sure the spacecraft was still capable. No problems for the old girl, and spacecraft had no problem in reorienting itself and locking back onto its guide star, Alpha Centauri.
This artist's concept shows NASA's two Voyager spacecraft exploring a turbulent region of space known as the heliosheath, the outer shell of the bubble of charged particles around our sun. Image credit: NASA/JPL-Caltech
There will be five more of these maneuvers over the next seven days, with the longest hold lasting three hours 50 minutes. The Voyager team plans to execute a series of weekly rolls for this purpose every three months.
Over the next few months, scientists will analyze the data.
“We do whatever we can to make sure the scientists get exactly the kinds of data they need, because only the Voyager spacecraft are still active in this exotic region of space,” said Jefferson Hall, Voyager mission operations manager at JPL. “We were delighted to see Voyager still has the capability to acquire unique science data in an area that won’t likely be traveled by other spacecraft for decades to come.”
Voyager 2 was launched on Aug. 20, 1977. Voyager 1 was launched on Sept. 5, 1977. On March 7, Voyager 1 was 17.4 billion kilometers (10.8 billion miles) away from the sun. Voyager 2 was 14.2 billion kilometers (8.8 billion miles) away from the sun, on a different trajectory.
The solar wind’s outward flow has not yet diminished to zero where Voyager 2 is exploring, but that may happen as the spacecraft approaches the edge of the bubble in the years ahead.
Ever imagine creating your own IMAX movie? Cinematographer Stephen Van Vuuren is working to do just that, and has created flythough sequences from thousands of images from the Cassini spacecraft’s tour of the Saturn system. The video above is just a sampling of this non-profit, giant-screen art film effort “that takes audiences on a journey of the mind, heart and spirit from the big bang to the near future via the Cassini-Huygens Mission at Saturn,” according to the “Outside In” website.
This is great! Blogger Brad Goodspeed created an animation which shows different planets in our solar system as they would appear in the sky if it shared an orbit with our Moon, 380,000 km from earth. On his blog, he said he created it “to make you feel small.” You succeeded, Brad!
Opportunity arrived at ‘Intrepid’ Crater on Mars during November 2010 and drove around crater rim. See rover wheel tracks at left. Intrepid crater was named in honor of the Apollo 12 lunar module named “Intrepid” – which landed two men on the moon on 19 November 1969. This false color mosaic was assembled from pancam images taken by Opportunity on Sol 2420 (Nov 14, 2010). Mosaic Credit: Kenneth Kremer, Marco Di Lorenzo NASA/JPL/Cornell
[/caption]
NASA recently celebrated the anniversary of the historic Apollo 12 lunar landing mission with another history making craft – the long lived Opportunity Mars rover. Opportunity traversed around and photographed ‘Intrepid’ crater on Mars in mid November 2010. The crater is informally named in honor of the ‘Intrepid’ lunar module which landed two humans on the surface of the moon on 19 November 1969, some forty one years ago.
Apollo 12 was only the second of NASA’s Apollo missions to place humans on the Earth’s moon. Apollo astronauts Pete Conrad and Gordon Bean precisely piloted their lunar landing spacecraft nicknamed ‘Intrepid’ to a safe touchdown in the ‘Ocean of Storms’, a mere 180 meters (600 feet) away from the Surveyor 3 robotic lunar probe which had already landed on the moon in April 1967. The unmanned Surveyor landers paved the way for NASA’s manned Apollo landers.
As Conrad and Bean walked on the moon and collected lunar rocks for science, the third member of the Apollo 12 crew, astronaut Dick Gordon, orbited alone in the ‘Yankee Clipper’ command module and collected valuable science data from overhead.
On the anniversary of the lunar landing, the rover science team decided to honor the Apollo 12 mission as Opportunity was driving east and chanced upon a field of small impact craters located in between vast Martian dune fields. Informal crater names are assigned by the team to craters spotted by Opportunity in the Meridiani Planum region based on the names of historic ships of exploration.
Opportunity rover took first panorama of Intrepid crater on Sol 2417 (Nov.11, 2010) which shows the rim of distant Endeavour crater in the background. Mosaic Credit: NASA/JPL/Cornell
Rover science team member James Rice, of NASA’s Goddard Space Flight Center, Greenbelt, Md., suggested using names from Apollo 12 because of the coincidental timing according to NASA. “The Apollo missions were so inspiring when I was young, I remember all the dates. When we were approaching these craters, I realized we were getting close to the Nov. 19 anniversary for Apollo 12,” Rice said. He sent Bean and Gordon photographs that Opportunity took of the two craters named for the two Apollo 12 spaceships.
Bean wrote back the following message to the Mars Exploration Rover team: “I just talked with Dick Gordon about the wonderful honor you have bestowed upon our Apollo 12 spacecraft. Forty-one years ago today, we were approaching the moon in Yankee Clipper with Intrepid in tow. We were excited to have the opportunity to perform some important exploration of a place in the universe other than planet Earth where humans had not gone before. We were anxious to give it our best effort. You and your team have that same opportunity. Give it your best effort.”
On November 4, Opportunity drove by and imaged ‘Yankee Clipper’ crater. After driving several more days she reached ‘Intrepid’ on November 9. The rover then traversed around the crater rim and photographed the crater interior from different vantage points, collecting two panoramic views along the way.
Opportunity soon departed Intrepid on Sol 2420 (Nov. 14) to resume her multi-year trek eastwards and took a series of crater images that day – from a very different direction – which we were inspired to assemble into a panoramic mosaic (in false color) in tribute to the Apollo 12 mission (see above).
Our mosaic tribute clearly shows the rover wheel tracks as Opportunity first approached Intrepid on Nov. 9 – which is fittingly reminiscent of the Apollo 12 astronauts walking on the moon 41 years ago as they explored a lunar crater. By comparison, the arrival mosaic from Sol 2417 shows distant Endeavour crater in the background.
Intrepid crater is about 16 meters in diameter, thus similar in size to ‘Eagle’ crater inside which Opportunity first landed on 24 January 2004 after a 250 million mile ‘hole in one shot’ from Earth. Eagle was named in honor of the Apollo 11 mission.
“Intrepid is fairly eroded with sand filling the interior and ejecta blocks planed off by the saltating sand”, said Matt Golembek, Mars Exploration Program Landing Site Scientist at the Jet Propulsion Laboratory (JPL), Pasadena, Calif. Asked about the age of Intrepid crater, Golembek told me; “Based on the erosional state it is at least several million years old, but less than around 20 million years old.”
Opportunity is blazing ahead towards a huge 22 km (14 mile) wide crater named ‘Endeavour’, which shows distinct signatures of clays and past wet environments based on orbital imagery thus making the crater a compelling science target.
“Intrepid is 1.5 km from Santa Maria crater and about 7.5 km from Endeavour.”
“We should be at Santa Maria crater next week, where we will spend the holidays and conjunction. Then it will be 6 km to Endeavour,” Golembek said.
The road ahead looks to be alot friendlier to the intrepid rover. “The terrain Opportunity is on is among the smoothest and easiest to traverse since Eagle and Endurance. Should be smooth sailing to Endeavour, averaging about 100 meters per drive sol. We should easily beat MSL to the phyllosilicates,” Golembek explained.
Phyllosilicates are clay minerals that form under wet, warm, non-acidic conditions. They have never before been studied on the Martian surface.
MSL is the Mars Science Lab, NASA’s next Mars lander mission and which is scheduled to blast off towards the end of 2011. Golembek leads the landing site selection team.
The amazing Opportunity rover has spent nearly seven years roving the Martian surface, conducting a crater tour during her very unexpectedly long journey at ‘Meridiani Planum’ on Mars which now exceeds 26 km (16 miles). The rovers were designed with a prime mission “warranty” of just 90 Martian days – or sols – and have vastly exceeded their creators expectations.
“What a ride. This still does not seem real,” Rob Manning told me. Manning headed the Entry, Descent and Landing team at JPL for both the Spirit and Opportunity rovers. “That would be fantastic if Opportunity could get to the phyllosilicates before MSL launches.”
Stay tuned.
This map of the region around NASA's Mars Exploration Rover Opportunity shows the relative locations of several craters and the rover location in May 2010. Credit: NASA/JPL-Caltech/Malin Space Science Systems/WUSTLAS12-48-7133 (20 Nov. 1969) --- This unusual photograph, taken during the second Apollo 12 extravehicular activity (EVA), shows two U.S. spacecraft on the surface of the moon. The Apollo 12 Lunar Module (LM) is in the background. The unmanned Surveyor 3 spacecraft is in the foreground. The Apollo 12 LM, with astronauts Charles Conrad Jr. and Alan L. Bean aboard, landed about 600 feet from Surveyor 3 in the Ocean of Storms. The television camera and several other pieces were taken from Surveyor 3 and brought back to Earth for scientific examination. Here, Conrad examines the Surveyor's TV camera prior to detaching it. Astronaut Richard F. Gordon Jr. remained with the Apollo 12 Command and Service Modules (CSM) in lunar orbit while Conrad and Bean descended in the LM to explore the moon. Surveyor 3 soft-landed on the moon on April 19, 1967.
Astronomers have been busy trying to determine the spin period and composition of Venus’ moon. December 8, 2010, results were announced by JPL/Caltech scientists, led by Michael Hicks.
“Wait a minute; back up”, I hear you ask. “Venus has a Moon?”
Of course it does. Well, kind of…
Let me explain.
It has the rather unfortunate name of 2002 VE68. That is because it was discovered on November 11, 2002 by LONEOS, the Lowell Observatory Near Earth Object Search. 2002 VE68 is an earth orbit-crossing asteroid that has been designated a Potential Hazardous Asteroid by the Minor Planet Center. For obvious reasons, this makes it a very interesting subject of study for JPL scientists.
2002 VE68 used to be a run of the mill, potential impact threat, Near Earth Object. But approximately 7000 years ago it had a close encounter with Earth that kicked it into a new orbit. It now occupies a place in orbit around the Sun where at its closest it wanders inside the orbit of Mercury and at its furthest it reaches just outside the orbit of the Earth. It is now in a 1:1 orbital resonance with Venus.
An orbital resonance is when two orbiting bodies exert a regular, periodic gravitational influence on each other due to their orbital periods being related by a ratio of two small numbers. For example, Pluto and Neptune are in an orbital resonance of 2:3, which simply means for every two times Pluto goes around the Sun, Neptune makes three trips around.
In the case of Venus and 2002 VE68, they both take the same time to orbit the Sun once. They are in a 1:1 orbital resonance. So by definition, 2002 VE68 is considered a quasi-satellite of Venus. If you watch the Orbital Viewer applet at the JPL small body page you can watch this celestial dance as the two bodies orbit the Sun and each other as 2002 VE68 dodges Earth and Mercury in the process.
Often these resonances result in an unstable interaction, in which the bodies exchange momentum and shift orbits until the resonance no longer exists. In this case, scientists believe 2002 VE68 will only remain a Venusian quasi-satellite for another 500 years or so.
So getting back to the story, Hicks and his team used the recent close apparition of 2002 VE68 to do photometric measurements over the course of three nights in November using the JPL Table Mountain 0.6m telescope near Wrightwood, California. From the color data they obtained they determined that 2002 VE68 is an X type asteroid. This is a group of asteroids with very similar spectra that could potentially have a variety of compositions. They are further broken down into Tholen classification types as either E, M or P types. Unfortunately Hicks’ team was not able to resolve the sub-classification with their equipment.
They were able to determine the approximate size of the asteroid to be 200 meters in diameter, based on its absolute magnitude, and they determined a spin rate of 13.5 hours. The amplitude of the fluctuation on the light curve of 2002 VE68 could imply hat it is actually a contact binary, two clumps of asteroidal material orbiting a center of mass in contact with each other.
For more information on some of the strange and curious beasts in the asteroidal zoo, visit the NASA Near Earth Object Program website.
