Caption: Dune symmetry on Mars. Credit: NASA/JPL/University of Arizona
It is so wonderful to see the Mars Reconnaissance Orbiter back in action, especially our favorite camera, the High-Resolution Imaging Science Experiment, or HiRISE. The HiRISE team released some of their latest images this week, and they are particularly stunning, including this one of symmetrical dunes in a small crater in Noachis Terra, west of the giant Hellas impact basin. Alfred McEwan, from the HiRISE team and the University of Arizona says the dunes here are linear, and are thought to be created due to shifting wind directions. In places, each dune is remarkably similar to adjacent dunes. The linear dune fields on Mars are similar to the ones seen on Titan, although not quite as large. The debris between the dunes are large boulders.
More images below, but on another note, HiRISE Twitter notes there will be a “big announcement” on Wednesday, January 20. A major discovery? Mission extension? Website redesign? Stay tuned.
This jaw-dropping beauty accompanied a press release announcing that 21 articles from HiRISE made up the entire contents of a special January issue of the journal Icarus . The papers analyzed Martian landforms shaped by winds, water, lava flow, seasonal icing and more.
This view shows color variations in bright layered deposits on a plateau near Juventae Chasma in the Valles Marineris region of Mars.
Contortions on the floor of Hellas Basin. Credit: NASA/JPL/University of Arizona
This almost looks like etchings on Mars’ surface, and they are very strange landforms indeed. McEwan notes that materials appear to have flowed in a viscous manner, like ice, here on the floor of Hellas Basin. Viscous flow features are common over the middle latitudes of Mars, but those in Hellas are especially unique, for unknown reasons.
Frost covered dunes. Credit: NASA/JPL/University of Arizona
This is a beautiful shot of frost covered dunes inside a crater. The HiRISE team says that on the floor of this crater where there are no dunes, the ice forms an uninterrupted layer. On the dunes however, dark streaks form as surface material from below the ice is mobilized and deposited on top of the ice. In some cases this mobile material probably slides down the steep face of the dune, while in other cases it may be literally blown out in a process of gas release similar to removing a cork from a champagne bottle.
Recent impact crater. Credit: NASA/JPL/University of Arizona
This impact crater could be relatively new, as it does not appear in images taken by the Viking Orbiters in 1976. McEwan said the HiRISE team suspects that the crater is more than several decades old, however, “because at full resolution we see a textured surface that is common in dust-mantled regions of Mars, but absent in the youngest craters.” While it could have been created recently, the other explanation is that there may have been more dust on the surface in 1976 or the air may have been hazy, obscuring the crater.
Click on each of the images for access to the higher resolution versions, or go directly to the HiRISE website.
Caption: The Phoenix Mars Lander, its backshell and its heatshield are visible within this enhanced-color image of the Phoenix landing site taken on Jan. 6, 2010 by the High Resolution Imaging Science Experiment (HiRISE) camera on NASA’s Mars Reconnaissance Orbiter. Image credit: NASA/JPL-Caltech/University of Arizona
Listen up, all you Phoenix lander fans! Beginning Jan. 18, the Mars Odyssey orbiter will start listening for any signs of life from Phoenix, which has been sitting silently on the frozen arctic region of Mars since its last communication in November 2008. The Phoenix team says hearing any radio transmission from the lander is high improbably, but possible. Never say never….
“We do not expect Phoenix to have survived, and therefore do not expect to hear from it. However, if Phoenix is transmitting, Odyssey will hear it,” said Chad Edwards, chief telecommunications engineer for the Mars Exploration Program at NASA’s Jet Propulsion Laboratory, Pasadena, Calif. “We will perform a sufficient number of Odyssey contact attempts that if we don’t detect a transmission from Phoenix, we can have a high degree of confidence that the lander is not active.”
Odyssey will pass over the Phoenix landing site approximately 10 times each day during three consecutive days of listening this month and two longer listening campaigns in February and March. The listening attempts will continue until after the sun is above the horizon for the full 24.7 hours of the Martian day at the lander’s high-latitude site. During the later attempts in February or March, Odyssey will transmit radio signals that could potentially be heard by Phoenix, as well as passively listening. Phoenix close up from July 2009. Annotated by Phil Stooke.
In the extremely unlikely case that Phoenix survived the winter, it is expected to follow instructions programmed on its computer. If systems still operate, once its solar panels generate enough electricity to establish a positive energy balance, the lander would periodically try to communicate with any available Mars relay orbiters in an attempt to reestablish contact with Earth. During each communications attempt, the lander would alternately use each of its two radios and each of its two antennas.
If Odyssey does hear from Phoenix, the orbiter will attempt to lock onto the signal and gain information about the lander’s status. The initial task would be to determine what capabilities Phoenix retains, information that NASA would consider in decisions about any further steps.
Phoenix landed in May, 2008 and worked for about five months before succumbing to the cold weather. Since then, Phoenix’s landing site has gone through autumn, winter and part of spring. The lander’s hardware was not designed to survive the temperature extremes and ice-coating load of an arctic Martian winter.
But who knows; our Mars spacecraft seemingly have a tendency to surprise us…
Opportunity leaves a mark on the Marquette Island rock on Mars. Credit: NASA/JPL/U of AZ, colorization by Stuart Atkinson
[/caption] Caption: Opportunity leaves a mark on the Marquette Island rock on Mars. Credit: NASA/JPL/U of AZ, colorization by Stuart Atkinson
The Opportunity Mars rover has been sitting by a rock called Marquette Island since early November 2009. The stay has given the rover a bit of a respite from the “pedal to the metal” driving regimen in its attempt to get to faraway Endeavour Crater. But Oppy hasn’t been just soaking in the rays, or kicking back doing nothing. She’s been conducting a thorough examination of the rock, and on Sol 2110 (Dec. 24, 2009), Oppy’s Rock Abrasion Tool dug in and left a mark on Marquette Island, a 1.5 millimeters (0.06 inch) hole. Then subsequent observations of the hole were made by the microscopic imager, to create a close-up mosaic of the innards of the rock, and the Mössbauer spectrometer was positioned on a different rock target for a long integration. Stu Atkinson created this colorized version of Oppy’s latest look at Marquette. After the rover hits the dusty trail again, will humans ever see Marquette Island again?
Stu has a few thoughts on that: “In a hundred years this rock will be on display in the Museum of Mars – just down the hall from the “MER Gallery” where Spirit and Oppy are displayed in all their restored glory,” Stu told me, “and there’ll be an attendant on duty beside it all the time, to stop tall, pale-skinned martian kids on school trips from leaning over the barrier and poking their dirty, sticky fingers into the hole Oppy ratted in it.”
Ah, yes! I’ve always loved Stu’s optimism! Check out more of his thoughts on his blog, Cumbrian Sky.
But back to the here an now, the plan ahead for Oppy is to collect an alpha particle X-ray spectrometer (APXS) spectrum and a MB spectrum from the RAT hole, before resuming the drive toward Endeavour crater. Obviously, the science team must find Marquette Island quite interesting to spend so much time there, and it will be interesting to hear the results of the observations.
As of Sol 2110 (Dec. 24, 2009), Opportunity’s solar-array energy production was 315 watt-hours with an atmospheric opacity (tau) of 0.491 and a dust factor of 0.509. Total odometry was 18,927.56 meters (11.76 miles).
Possible habitable zones around stars. Credit: Kepler mission
The Kepler mission announced the discovery of 5 new extrasolar planets today at the American Astronomical Society meeting in Washington, DC, each with some very unusual properties. But additionally, the space telescope has spotted some Jupiter-sized objects orbiting stars, and these objects are hotter than the host star. The science team has no idea what these objects could be, but they are part of 100 planetary candidates Kepler has observed that are still being analyzed.
The Kepler mission’s objective is to search for Earth-size planets in the habitable zones of other stars, and the planets announced today are comparable in size to Neptune, Jupiter and the other gas giants of our solar system but are substantially less dense. This first set of five new planets discovered by the Kepler mission was discovered in the first six weeks of the telescope’s operation. “The quick discovery indicates that Kepler is performing well,” said William Borucki, from NASA’s Ames Research Center.
One of these new planets is similar in many ways to Neptune, although its irradiation level is much higher. A second planet is one of the least dense planets ever discovered, and along with the other three, confirms the existence of planets with densities substantially lower than those predicted for gas giant planets. Borucki said Kepler 7b has the density of styrofoam, at .17 grams per cubic centimeter, basically a density of zero.
The smallest planet, Kepler 4b, is 4.31 earth radii, or about Neptune-sized. The other four about the size of Jupiter. All five planets have short orbital periods, and follow-up observations will be made with ground-based telescopes.
Since these planets are close to their host stars, they are very hot, hotter than about 1500 K. 1300 K is the temperature where molten lava flows.
Kepler launched in March 2009 and the mission is expected to last 3½ years. The team now has an additional 8 months of data are now available to analyze. Borucki said in 2010 Kepler will focus on the discovery of smaller planets, with an Earth-sized planet being the “holy grail” of exoplanet discoveries.
Other objects detected by Kepler include unusual variable stars, including binaries, oscillating stars, pulsating variables, and more, including other extrasolar planets, but declined to divulge more, saying his team has to be patient and do the confirmations on all the objects before.
Borucki also said data from Kepler will be released to the public on a regular basis starting in June 2010.
Will Spirit have a happy 2010? Let's hope so! Image created by Stu Atkinson.
In just a few days, the Spirit rover will celebrate six incredible years on Mars. But JPL put out a press release today, as well as the video above, saying the outlook for Spirit’s survival is not good. Being stuck in a sand trap with wheels that aren’t working well are challenges to Spirit’s mobility that could prevent the rover team from using a key survival strategy — positioning the rover’s solar panels to tilt toward the sun to collect power for heat to survive the severe Martian winter. “The highest priority for this mission right now is to stay mobile, if that’s possible,” said Steve Squyres, principal investigator for the rovers.
I’m still holding out hope, however, that the rover team will work another miracle, and that 2010 will be another happy year for Spirit on Mars — see the image below created by Stu Atkinson.
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But if mobility is not possible, the next priority is survival. To to that, the rover team will attempt to improve the rover’s tilt, while Spirit is able to generate enough electricity to turn its wheels. Spirit is in the southern hemisphere of Mars, where it is autumn, and the amount of daily sunshine available for the solar-powered rover is declining. This could result in ceasing extraction activities as early as January, depending on the amount of remaining power. Spirit’s tilt, nearly five degrees toward the south, is unfavorable because the winter sun crosses low in the northern sky.
Unless the tilt can be improved or luck with winds affects the gradual buildup of dust on the solar panels, the amount of sunshine available will continue to decline until May 2010. During May, or perhaps earlier, Spirit may not have enough power to remain in operation.
“At the current rate of dust accumulation, solar arrays at zero tilt would provide barely enough energy to run the survival heaters through the Mars winter solstice,” said Jennifer Herman, a rover power engineer at NASA’s Jet Propulsion Laboratory in Pasadena, Calif.
The team is evaluating strategies for improving the tilt even if Spirit cannot escape the sand trap, such as trying to dig in deeper with the wheels on the north side. In February, NASA will assess Mars missions, including Spirit, for their potential science versus costs to determine how to distribute limited resources. Meanwhile, the team is planning additional research about what a stationary Spirit could accomplish as power wanes.
“Spirit could continue significant research right where it is,” said Ray Arvidson of Washington University in St. Louis, deputy principal investigator for the rovers. “We can study the interior of Mars, monitor the weather and continue examining the interesting deposits uncovered by Spirit’s wheels.”
A study of the planet’s interior would use radio transmissions to measure wobble of the planet’s axis of rotation, which is not feasible with a mobile rover. That experiment and others might provide more and different findings from a mission that has already far exceeded expectations.
Moons dancing around Saturn. Credit: NASA/JPL/Space Science
Moons dancing around Saturn. Credit: NASA/JPL/Space Science Institute
The Cassini CICLOPS imaging team has released some new movies of several moons orbiting Saturn as if in a cosmic ballet around the ringed planet. In one scene that blends 12 images taken over the span of 19 minutes, Rhea skates in front of Janus, as Mimas and Pandora slide across the screen in the opposite direction.
“As yet another year in Saturn orbit draws to a close, these wondrous movies of an alien place clear across the solar system remind us how fortunate we are to be engaged in this magnificent exploratory expedition,” said Carolyn Porco, Cassini imaging team leader.
While the dance appears leisurely on screen, Rhea actually orbits Saturn at a speed of about 8 kilometers per second (18,000 mph). The other moons are hurtling around the planet even faster. Mimas averages about 14 kilometers per second (31,000 mph), and Janus and Pandora travel at about 16 kilometers per second (36,000 mph).
Elements of the ESA-NASA ExoMars program 2016-2018. Credit: ESA
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The new joint Mars exploration program of NASA and ESA is quickly pushing forward to implement an agreed upon framework to construct an ambitious new generation of red planet orbiters and landers starting with the 2016 and 2018 launch windows.
The European-led ExoMars Trace Gas Mission Orbiter (TGM) has been selected as the first spacecraft of the joint initiative and is set to launch in January 2016 aboard a NASA supplied Atlas 5 rocket for a 9 month cruise to Mars. The purpose is to study trace gases in the martian atmosphere, in particular the sources and concentration of methane which has significant biological implications. Variable amounts of methane have been detected by a martian orbiter and ground based telescopes on earth. The orbiter will likely be accompanied by a small static lander provided by ESA and dubbed the Entry, Descent and Landing Demonstrator Module (EDM).
The NASA Mars Program is shifting its science strategy to coincide with the new joint venture with ESA and also to build upon recent discoveries from the current international fleet of martian orbiters and surface explorers Spirit, Opportunity and Phoenix (see my earlier mars mosaics). Doug McCuiston, NASA’s director of Mars Exploration at NASA HQ told me in an interview that, “NASA is progressing quickly from ‘Follow the Water’ through assessing habitability and on to a theme of ‘Seeking the Signs of Life’. Looking directly for life is probably a needle in the haystack, but the signatures of past or present life may be more wide spread through organics, methane sources, etc”.
NASA and ESA will issue an “Announcement of Opportunity for the orbiter in January 2010” soliciting proposals for a suite of science instruments according to McCuiston. “The science instruments will be competitively selected. They are open to participation by US scientists who can also serve as the Principal Investigators (PI’s)”. Proposals are due in 3 months and will be jointly evaluated by NASA and ESA. Instrument selections are targeted for announcement in July 2010 and the entire cost of the NASA funded instruments is cost capped at $100 million.
Mars Trace Gas Mission orbiter slated for 2016 launch is the first spacecraft in the new ESA & NASA Mars Exploration Joint Initiative. Credit: NASA ESA
“The 2016 mission must still be formally approved by NASA after a Preliminary Design Review, which will occur either in late 2010 or early 2011. Funding until then is covered in the Mars Program’s Next Decade wedge, where all new-start missions reside until approved, or not, by the Agency”, McCuiston told me. ESA’s Council of Ministers just gave the “green light” and formally approved an initial budget of 850 million euros ($1.2 Billion) to start implementing their ExoMars program for the 2016 and 2018 missions on 17 December at ESA Headquarters in Paris, France. Another 150 million euros will be requested within two years to complete the funding requirement for both missions.
ESA has had to repeatedly delay its own ExoMars spacecraft program since it was announced several years ago due to growing complexity, insufficient budgets and technical challenges resulting in a de-scoping of the science objectives and a reduction in weight of the landed science payload. The ExoMars rover was originally scheduled to launch in 2009 and is now set for 2018 as part of the new architecture.
The Trace Gas orbiter combines elements of ESA’s earlier proposed ExoMars orbiter and NASA’s proposed Mars Science Orbiter. As currently envisioned the spacecraft will have a mass of about 1100 kg and carry a roughly 115 kg science payload, the minimum deemed necessary to accomplish its goals. The instruments must be highly sensitive in order to be capable of detecting the identity and extremely low concentration of atmospheric trace gases, characterizing the spatial and temporal variation of methane and other important species, locating the source origin of the trace gases and determining if they are caused by biologic or geologic processes. Current photochemical models cannot explain the presence of methane in the martain atmosphere nor its rapid appearance and destruction in space, time or quantity.
An Atlas rocket similar to this vehicle I observed at Cape Canaveral Pad 41 is projected to launch the 2016 Mars orbiter. Credit: Ken Kremer
Among the instruments planned are a trace gas detector and mapper, a thermal infrared imager and both a wide angle camera and a high resolution stereo color camera (1 – 2 meter resolution). “All the data will be jointly shared and will comply with NASA’s policies on fully open access and posting into the Planetary Data System”, said McCuiston.
Another key objective of the orbiter will be to establish a data relay capability for all surface missions up to 2022, starting with 2016 lander and two rovers slotted for 2018. This timeframe could potentially coincide with Mars Sample Return missions, a long sought goal of many scientists.
If the budget allows, ESA plans to piggyback a small companion lander (EDM) which would test critical technologies for future missions. McCuiston informed me that, “The objective of this ESA Technology Demonstrator is validating the ability to land moderate payloads, so the landing site selection will not be science-driven. So expect something like Meridiani or Gusev—large, flat and safe. NASA will assist ESA engineering as requested, and within ITAR constraints.” EDM will use parachutes, radar and clusters of pulsing liquid propulsion thrusters to land.
“ESA plans a competitive call for instruments on their 3-4 kg payload”, McCuiston explained. “The Announcement of Opportunity will be open to US proposers as well so there may be some US PI’s. ESA wants a camera to ‘prove’ they got to the ground. Otherwise there is no significant role planned for NASA in the EDM”.
The lander would likely function as a weather station and be relatively short lived, perhaps 8 Sols or martian days, depending on the capacity of the batteries. ESA is not including a long term power source, such as from solar arrays, so the surface science will thus be limited in duration.
The orbiter and lander would separate upon arrival at Mars. The orbiter will use a series of aerobraking maneuvers to eventually settle into a 400 km high circular science orbit inclined at about 74 degrees.
The joint Mars architecture was formally agreed upon last summer at a bilateral meeting between Ed Weiler (NASA) and David Southwood (ESA) in Plymouth, UK. Weiler is NASA’s Associate Administrator for the Science Mission Directorate and Southwood is ESA’s Director of Science and Robotic Exploration. They signed an agreement creating the Mars Exploration Joint Initiative (MEJI) which essentially weds the Mars programs of NASA and ESA and delineates their respective program responsibilities and goals.
“The key to moving forward on Mars exploration is international collaboration with Europe”, Weiler said to me in an interview. “We don’t have enough money to do these missions separately. The easy things have been done and the new ones are more complex and expensive. Cost overruns on Mars Science Lab (MSL) have created budgetary problems for future mars missions”. To pay for the MSL overrun, funds have to be taken from future mars budget allocations from fiscal years 2010 to 2014.
“2016 is a logical starting point to work together. NASA can have a 2016 mission if we work with Europe but not if we work alone. We can do so much more by working together since we both have the same objectives scientifically and want to carry out the same types of mission”. Weiler and Southwood instructed their respective science teams to meet and lay out a realistic and scientifically justifiable approach. Weiler explained to me that his goal and hope was to reinstate an exciting Mars architecture with new spacecraft launching at every opportunity which occurs every 26 months and which advance the state of the art for science. “It’s very important to demonstrate a critical new technology on each succeeding mission”.
More on the 2018 mission plan and beyond in a follow up report.
Mars from orbit. Valles Marineris and Volcanic region
This image shows the first flash of sunlight reflected off a lake on Saturn’s moon Titan. Credit: NASA/JPL
Dear friend,
Ah, yes. Another gorgeous day here in the northern lake district. It warmed up to about 94 K (-179 °C, or -290 °F) and we sat and enjoyed the sunshine gleaming off the liquid lakes here on Titan. Wish you were here!
Liquid lakes? Gleaming sunshine? Titan?
Yes, it’s all true. The Cassini Spacecraft has captured the first flash of sunlight reflected off a lake on Saturn’s moon Titan, confirming the presence of liquid on the part of the moon dotted with many large, lake-shaped basins.
Cassini scientists had been looking for the glint, also known as a specular reflection, since the spacecraft began orbiting Saturn in 2004. But Titan’s northern hemisphere, which has more lakes than the southern hemisphere, has been veiled in winter darkness. The sun only began to directly illuminate the northern lakes recently as it approached the equinox of August 2008, the start of spring in the northern hemisphere. Titan’s hazy atmosphere also blocked out reflections of sunlight in most wavelengths. This serendipitous image was captured on July 8, 2009, using Cassini’s visual and infrared mapping spectrometer.
This image is being presented at the fall meeting of the American Geophysical Union in San Francisco.
“This one image communicates so much about Titan — thick atmosphere, surface lakes and an otherworldliness,” said Bob Pappalardo, Cassini project scientist, based at NASA’s Jet Propulsion Laboratory, Pasadena, Calif. “It’s an unsettling combination of strangeness yet similarity to Earth. This picture is one of Cassini’s iconic images.”
Titan, Saturn’s largest moon, has captivated scientists because of its many similarities to Earth. Scientists have theorized for 20 years that Titan’s cold surface hosts seas or lakes of liquid hydrocarbons, making it the only other planetary body besides Earth believed to harbor liquid on its surface. While data from Cassini have not indicated any vast seas, they have revealed large lakes near Titan’s north and south poles.
In 2008, Cassini scientists using infrared data confirmed the presence of liquid in Ontario Lacus, the largest lake in Titan’s southern hemisphere. But they were still looking for the smoking gun to confirm liquid in the northern hemisphere, where lakes are also larger.
Katrin Stephan, of the German Aerospace Center (DLR) in Berlin, an associate member of the Cassini visual and infrared mapping spectrometer team, was processing the initial image and was the first to see the glint on July 10th.
“I was instantly excited because the glint reminded me of an image of our own planet taken from orbit around Earth, showing a reflection of sunlight on an ocean,” Stephan said. “But we also had to do more work to make sure the glint we were seeing wasn’t lightning or an erupting volcano.”
Team members at the University of Arizona, Tucson, processed the image further, and scientists were able to compare the new image to radar and near-infrared-light images acquired from 2006 to 2008.
They were able to correlate the reflection to the southern shoreline of a lake called Kraken Mare. The sprawling Kraken Mare covers about 400,000 square kilometers (150,000 square miles), an area larger than the Caspian Sea, the largest lake on Earth. It is located around 71 degrees north latitude and 337 degrees west latitude.
The finding shows that the shoreline of Kraken Mare has been stable over the last three years and that Titan has an ongoing hydrological cycle that brings liquids to the surface, said Ralf Jaumann, a visual and infrared mapping spectrometer team member who leads the scientists at the DLR who work on Cassini. Of course, in this case, the liquid in the hydrological cycle is methane rather than water, as it is on Earth.
“These results remind us how unique Titan is in the solar system,” Jaumann said. “But they also show us that liquid has a universal power to shape geological surfaces in the same way, no matter what the liquid is.”
his is a locations and field of view map of the twenty all-sky imagers used in support of the THEMIS mission. Twenty all-sky imagers (ASIs) were deployed by researchers from the University of California Berkeley, the University of Calgary, and the University of Alaska in support of the THEMIS mission. Credit: THEMIS/UC Berkeley
Colliding auroras photographed by THEMIS all-sky imagers (ASIs) on Feb. 29, 2008. Credit: Toshi Nishimura/UCLA
Scientists recently discovered something about auroras they never knew before. “Our jaws dropped when we saw the movies for the first time,” said Larry Lyons of the University of California-Los Angeles,(UCLA) describing how sometimes, vast curtains of aurora borealis collide, producing spectacular outbursts of light. “These outbursts are telling us something very fundamental about the nature of auroras.” These collisions can be so large, that isolated observers on Earth — with limited fields of view — have never noticed them before. It took a network of sensitive cameras spread across thousands of miles to get the big picture.
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This network of 20 cameras, set up by NASA and the Canadian Space Agency was deployed around the Arctic in support of the THEMIS mission, the “Time History of Events and Macroscale Interactions during Substorms.” THEMIS consists of five identical probes launched in 2006 to solve a long-standing mystery: Why do auroras occasionally erupt in an explosion of light called a substorm?
The cameras would photograph auroras from below while the spacecraft sampled charged particles and electromagnetic fields from above. Together, the on-ground cameras and spacecraft would see the action from both sides and be able to piece together cause and effect—or so researchers hoped. It seems to have worked. This three frame animation of THEMIS/ASI images shows auroras colliding on Feb. 29, 2008. Credit: Toshi Nishimura/UCLA
The breakthrough came earlier this year when UCLA researcher Toshi Nishimura assembled continent-wide movies from the individual ASI cameras. “It can be a little tricky,” Nishimura said. “Each camera has its own local weather and lighting conditions, and the auroras are different distances from each camera. I’ve got to account for these factors for six or more cameras simultaneously to make a coherent, large-scale movie.”
The first movie he showed Lyons was a pair of auroras crashing together in Dec. 2007. “It was like nothing I had seen before,” Lyons recalled. “Over the next several days, we surveyed more events. Our excitement mounted as we became convinced that the collisions were happening over and over.” A schematic diagram of Earth's magnetosphere. Earth is the circle near the middle and the plasma tail is denoted in yellow. Credit: Larry Lyons/UCLA
The explosions of light, they believe, are a sign of something dramatic happening in the space around Earth—specifically, in Earth’s “plasma tail.” Millions of kilometers long and pointed away from the sun, the plasma tail is made of charged particles captured mainly from the solar wind. Sometimes called the “plasma sheet,” the tail is held together by Earth’s magnetic field.
The same magnetic field that holds the tail together also connects it to Earth’s polar regions. Because of this connection, watching the dance of Northern Lights can reveal much about what’s happening in the plasma tail.
THEMIS project scientist Dave Sibeck of NASA’s Goddard Space Flight Center, Greenbelt, Md. said, “By putting together data from ground-based cameras, ground-based radar, and the THEMIS spacecraft, we now have a nearly complete picture of what causes explosive auroral substorms,”
Lyons and Nishimura have identified a common sequence of events. It begins with a broad curtain of slow-moving auroras and a smaller knot of fast-moving auroras, initially far apart. The slow curtain quietly hangs in place, almost immobile, when the speedy knot rushes in from the north. The auroras collide and an eruption of light ensues.
How does this sequence connect to events in the plasma tail? Lyons believes the fast-moving knot is associated with a stream of relatively lightweight plasma jetting through the tail. The stream gets started in the outer regions of the plasma tail and moves rapidly inward toward Earth. The fast knot of auroras moves in synch with this stream.
Meanwhile, the broad curtain of auroras is connected to the stationary inner boundary of the plasma tail and fueled by plasma instabilities there. When the lightweight stream reaches the inner boundary of the plasma tail, there is an eruption of plasma waves and instabilities. This collision of plasma is mirrored by a collision of auroras over the poles.
Movies of the phenomenon were unveiled at the Fall Meeting of the American Geophysical Union today in San Francisco.
Herschel looks deep inside the heart of a dark cloud located 1000 light years away in the constellation Aquila, the Eagle.Credit: ESA and the SPIRE and PACS consortia
The science teams from the Herchel telescope are meeting this week to discuss their first results from the intial months of observations by the newest infrared space telescope, which was launched in May. While details of the scientific findings won’t be released until Friday after everyone at the meetings has had a chance to share their results, ESA released a few stunning new pictures to give everyone a sample of what is to come. In addition to the images shown here, hints of other upcoming images include the most distant known quasar, a dwarf planet, and water sublimating from a comet’s surface. Some of the images have been described as among the most important images obtained from space for decades.
Above, Herschel peered deep inside an unseen stellar nursery in located 1000 light years away in the constellation Aquila, the Eagle, revealing a surprising amounts of activity. Some 700 newly-forming stars are estimated to be crowded into filaments of dust stretching through the image. The image is the first new release of ‘OSHI’, ESA’s Online Showcase of Herschel Images.
Herschel's look at the Southern Cross. Credits: ESA and the PACS consortium
Another images release of the Southern Cross shows that even the darkest patches of sky can shine brightly to Herschel. Usually, this region looks like a bland cloud of dust, but Herschel shows it to be a place of intense star formation with filaments and condensations of dust cocooning newly forming stars. The dust forms into clumps along magnetic lines – like pearls on a necklace. Each clump is a very early star – at its embryonic stage.
The third image is of the spiral galaxy M51, also known as the Whirlpool Galaxy, showing off its spectacular infrared colors. Two huge waves of star formation encircle its central nucleus, making beautiful spiral arms. Each one shines brightly with its dust being warmed by the young stars. Herschel's Whirlpool Galaxy. Credit: ESA and PACS team
