For many of them, long before they are ever launched into space, they are tested from NASA airplanes. One of the objectives of the NASA Airborne Science Program is to test new instruments in space-like environments. Testing future satellite instruments from airplanes is the next best thing to actually testing them in space.

Over the past three weeks, a team from NASA's Goddard Space Flight Center, Greenbelt, Md., led by Bill Heaps has been testing a new broadband lidar instrument on NASA’s DC-8 flying laboratory that they hope will fly on the ASCENDS satellite mission. ASCENDS, an acronym for Active Sensing of Carbon dioxide Emissions over Nights, Days and Seasons, is an upcoming NASA satellite expected to be launched in 2018-2020. The goal of the ASCENDS mission is to measure the sources, distribution and variations in carbon dioxide gas with very high precision all over the Earth. Mapping carbon dioxide is important for understanding the global carbon cycle and for modeling global climate change.

How is carbon dioxide measured from space?

Carbon dioxide makes up a very small fraction of the gas in Earth’s atmosphere. In addition, the majority of the carbon dioxide variability occurs in the first 100 feet above the surface of the Earth. In order to measure the abundance of carbon dioxide from a satellite, any instrument must therefore look through Earth’s entire atmosphere in order to detect the variations in carbon dioxide occurring near the surface.

Heaps’ broadband lidar – an acronym for light detection and ranging -- uses an infrared laser beam aimed at the surface of the Earth. As the laser passes through the atmosphere and bounces off the ground, carbon dioxide molecules in the atmosphere absorb some of the light from the laser. Measuring the amount of absorption that occurs as the instrument passes over different locations on the Earth will allow the team to build global carbon dioxide maps.

Typical lidar systems have lasers that emit light at very specific colors, or wavelengths. The carbon dioxide molecule, however, absorbs light at a several different infrared wavelengths. The broadband laser used in Heaps’ instrument emits light with a broader range of wavelengths, and thus has the advantage of being able to detect carbon dioxide absorption in multiple wavelength bands with one laser. The wavelength control requirements are also less strict than for a more conventional narrowband laser, which may make the system easier to implement on a satellite.

The Goddard team worked for over two weeks to install and test their instrument in the belly of the DC-8 at the NASA Dryden Aircraft Operations Facility in Palmdale, Calif.

The team then flew with their instrument on two four-hour flights on the converted jetliner during the week of May 2 – 6 over northern and central California. During the flights, they tested the instrument’s performance at variety of altitudes and over different types of surfaces – deserts, agricultural fields, mountainous terrain, the ocean and the flat waters of Lake Tahoe. The team was very pleased with the performance of the instrument.

“The system definitely measured CO2 on both flights, even transmitting a very small amount of laser power. I believe the broadband technique has excellent potential to be scaled up for measurements from space,” Heaps said.

This July, several instrument teams, all vying to have their instrument fly on ASCENDS, will test their instruments side-by-side on the DC-8. With data from the test flights of the broadband lidar instrument in hand, Heaps’ team will return to Goddard to make refinements and improvements in the hope that their instrument will be chosen to fly on the ASCENDS satellite mission.

The NASA Earth Science Technology Office Instrument Incubator program provided funding for the Goddard broadband lidar.

For more information visit http://www.nasa.gov/centers/dryden/Features/broadband_lidar_tested.html

The nebula is the wreckage of an exploded star that emitted light which reached Earth in the year 1054. It is located 6,500 light-years away in the constellation Taurus. At the heart of an expanding gas cloud lies what is left of the original star's core, a superdense neutron star that spins 30 times a second. With each rotation, the star swings intense beams of radiation toward Earth, creating the pulsed emission characteristic of spinning neutron stars (also known as pulsars).

Apart from these pulses, astrophysicists believed the Crab Nebula was a virtually constant source of high-energy radiation. But in January, scientists associated with several orbiting observatories, including NASA's Fermi, Swift and Rossi X-ray Timing Explorer, reported long-term brightness changes at X-ray energies.

"The Crab Nebula hosts high-energy variability that we're only now fully appreciating," said Rolf Buehler, a member of the Fermi Large Area Telescope (LAT) team at the Kavli Institute for Particle Astrophysics and Cosmology, a facility jointly located at the Department of Energy's SLAC National Accelerator Laboratory and Stanford University.

Since 2009, Fermi and the Italian Space Agency's AGILE satellite have detected several short-lived gamma-ray flares at energies greater than 100 million electron volts (eV) -- hundreds of times higher than the nebula's observed X-ray variations. For comparison, visible light has energies between 2 and 3 eV.

On April 12, Fermi's LAT, and later AGILE, detected a flare that grew about 30 times more energetic than the nebula's normal gamma-ray output and about five times more powerful than previous outbursts. On April 16, an even brighter flare erupted, but within a couple of days, the unusual activity completely faded out.

"These superflares are the most intense outbursts we've seen to date, and they are all extremely puzzling events," said Alice Harding at NASA's Goddard Space Flight Center in Greenbelt, Md. "We think they are caused by sudden rearrangements of the magnetic field not far from the neutron star, but exactly where that's happening remains a mystery."

The Crab's high-energy emissions are thought to be the result of physical processes that tap into the neutron star's rapid spin. Theorists generally agree the flares must arise within about one-third of a light-year from the neutron star, but efforts to locate them more precisely have proven unsuccessful so far.

Since September 2010, NASA's Chandra X-ray Observatory routinely has monitored the nebula in an effort to identify X-ray emission associated with the outbursts. When Fermi scientists alerted astronomers to the onset of a new flare, Martin Weisskopf and Allyn Tennant at NASA's Marshall Space Flight Center in Huntsville, Ala., triggered a set of pre-planned observations using Chandra.

"Thanks to the Fermi alert, we were fortunate that our planned observations actually occurred when the flares were brightest in gamma rays," Weisskopf said. "Despite Chandra's excellent resolution, we detected no obvious changes in the X-ray structures in the nebula and surrounding the pulsar that could be clearly associated with the flare."

Scientists think the flares occur as the intense magnetic field near the pulsar undergoes sudden restructuring. Such changes can accelerate particles like electrons to velocities near the speed of light. As these high-speed electrons interact with the magnetic field, they emit gamma rays.

To account for the observed emission, scientists say the electrons must have energies 100 times greater than can be achieved in any particle accelerator on Earth. This makes them the highest-energy electrons known to be associated with any cosmic source. Based on the rise and fall of gamma rays during the April outbursts, scientists estimate that the size of the emitting region must be comparable in size to the solar system.

NASA's Fermi is an astrophysics and particle physics partnership managed by NASA's Goddard Space Flight Center in Greenbelt, Md., and developed in collaboration with the U.S. Department of Energy, with important contributions from academic institutions and partners in France, Germany, Italy, Japan, Sweden and the United States.

The Marshall Space Flight Center manages the Chandra program for NASA's Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory controls Chandra's science and flight operations from Cambridge, Mass.

For more information visit http://www.nasa.gov/mission_pages/GLAST/news/crab-flare.html

ASTER combines infrared, red, and green wavelengths of light to make false-color images that distinguish between water and land. Water is blue. Buildings and paved surfaces are blue-gray. Vegetation is red.

The images to the right are from an observation that occurred on May 4, 2011 at 11:45 A.M. local time (1645 UTC), near Tuscaloosa, Ala.

The physical principle guiding the use of satellite data to detect tornado damage is based on the premise that the strong winds associated with a tornado will change the physical characteristics of the surface in such a way as to alter the visible and infrared energy reflected. These characteristics could be a change in the orientation of surface features, such as the complete destruction of a house in a residential area, the snapping of trees in a forest region, the uprooting of crops in an agriculture area, or minimal damage to grassland in a pasture or field.

Images from NASA satellites will aid in damage assessment, determining the tornado width and path length. Further scientific analysis using satellite imagery is planned.

Terra/ASTER is a joint activity between NASA's Science Mission Directorate Earth Science Division and Japan's Ministry of Economy, Trade and Industry. Terra is one of 14 NASA satellites that look at the Earth to study and understand changes in the Earth system and provide societal benefits.

The NASA image created by the Short-term Prediction and Research Transition or SPoRT project at the Marshall Space Flight Center in Huntsville, using data provided courtesy of NASA Goddard Space Flight Center, the Land Processes Distributed Active Archive Center, Japan’s Earth Remote Sensing Data Analysis Center, the Ministry of Economy, Trade and Industry, along with the Japan Research Observation System Organization.

For more information visit http://www.nasa.gov/topics/earth/features/tuscaloosa_tornado.html

A combination of heavy rains and a large snow melt has put parts of the central U.S. at risk for record flooding this spring with several locations along the Mississippi already at or near record levels. One likely culprit is La Niña. Despite the fact that the current La Niña appears to be winding down, its effects in the atmosphere can persist for a while. Furthermore, although not every La Niña brings major flooding to the region, La Niña's are conducive for above-normal rainfall from East Texas and northern Louisiana up through Arkansas and the Tennessee and Ohio Valleys with below-normal rainfall across Texas, southern Louisiana and Florida.

During La Niña, below-normal sea surface temperatures occur in the equatorial East Pacific and above-normal temperatures in the West Pacific. This pattern leads to enhanced tropical thunderstorm activity over the West Pacific, which in turn can influence the weather in middle latitudes by shifting the jet stream pattern. On average, La Niña's favor an upper-level trough over the Midwest with the jet stream dipping down out of the northern Rockies and flowing west-to-east across the central Mississippi and Ohio Valleys before heading back up over the Northeast. This pattern steers developing low pressure systems across the Plains and central Mississippi into the Tennessee and Ohio Valleys. These areas of low pressure provide the focus for showers and storms while drawing warm moist air up from the Gulf of Mexico, resulting in enhanced rainfall across the central part of the country.

The main objective of the Tropical Rainfall Measuring Mission or TRMM satellite is to measure rainfall over the global Tropics. TRMM measures rainfall using a combination of passive microwave and active radar sensors. For expanded coverage, TRMM can be used to calibrate rainfall estimates from other satellites. The TRMM-based, near-real time Multi-satellite Precipitation Analysis (TMPA) at the NASA Goddard Space Flight Center, Greenbelt, Md. provides rainfall estimates over the global Tropics.

TMPA rainfall anomalies were created in a rainfall map for the period April 4 to May 4, 2011 for the eastern two thirds of the country. The anomalies were constructed by computing the average rainfall rate over the period and then subtracting the 10-year average rate for the same period. The resulting pattern shows a broad area of above-normal rainfall (shown in green and blue) stretching from eastern Oklahoma across the central Mississippi Valley and up into the lower Ohio Valley with below-normal rainfall along the northern Gulf Coast. This rainfall pattern is consistent with a La Niña.

In addition to rainfall, this type of jet stream pattern can lead to strong storms by allowing strong jet stream winds to override warm moist air from the Gulf as was evidenced by the recent tornado outbreak. In fact, some of the biggest tornado outbreaks, including the previous record "Super Outbreak" in 1974, have occurred during La Niña's.

TRMM is a joint mission between NASA and the Japanese space agency JAXA.

For more information visit http://www.nasa.gov/topics/earth/features/spring-rainfall.html

"That is what happens with these long-period comets that come in from way outside our planetary system," said Don Yeomans of NASA's Near-Earth Object Program Office at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "They make these long, majestic, speedy arcs through our solar system, and sometimes they put on a great show. But not Elenin. Right now that comet looks kind of wimpy."

How does a NASA scientist define cometary wimpiness?

"We're talking about how a comet looks as it safely flies past us," said Yeomans. "Some cometary visitors arriving from beyond the planetary region – like Hale-Bopp in 1997 -- have really lit up the night sky where you can see them easily with the naked eye as they safely transit the inner-solar system. But Elenin is trending toward the other end of the spectrum. You'll probably need a good pair of binoculars, clear skies, and a dark, secluded location to see it even on its brightest night."

Comet Elenin should be at its brightest shortly before the time of its closest approach to Earth on Oct. 16 of this year. At its closest point, it will be 35 million kilometers (22 million miles) from us. Can this icy interloper influence us from where it is, or where it will be in the future? What about this celestial object inspiring some shifting of the tides or even tectonic plates here on Earth? There have been some incorrect Internet speculations that external forces could cause comet Elenin to come closer.

"Comet Elenin will not encounter any dark bodies that could perturb its orbit, nor will it influence us in any way here on Earth," said Yeomans. "It will get no closer to Earth than 35 million kilometers [about 22 million miles]. "

"Comet Elenin will not only be far away, it is also on the small side for comets," said Yeomans. "And comets are not the most densely-packed objects out there. They usually have the density of something akin to loosely packed icy dirt.

"So you've got a modest-sized icy dirtball that is getting no closer than 35 million kilometers," said Yeomans. "It will have an immeasurably miniscule influence on our planet. By comparison, my subcompact automobile exerts a greater influence on the ocean's tides than comet Elenin ever will."

Yeomans did have one final thought on comet Elenin.

"This comet may not put on a great show. Just as certainly, it will not cause any disruptions here on Earth. But there is a cause to marvel," said Yeomans. "This intrepid little traveler will offer astronomers a chance to study a relatively young comet that came here from well beyond our solar system's planetary region. After a short while, it will be headed back out again, and we will not see or hear from Elenin for thousands of years. That's pretty cool."

NASA detects, tracks and characterizes asteroids and comets passing relatively close to Earth using both ground- and space-based telescopes. The Near-Earth Object Observations Program, commonly called "Spaceguard," discovers these objects, characterizes a subset of them, and predicts their paths to determine if any could be potentially hazardous to our planet.

JPL manages the Near-Earth Object Program Office for NASA's Science Mission Directorate in Washington, DC. JPL is a division of the California Institute of Technology in Pasadena.

For more information visit http://www.jpl.nasa.gov/news/news.cfm?release=2011-135

At the start of this three-month final approach to this massive body in the asteroid belt, Dawn is 1.21 million kilometers (752,000 miles) from Vesta, or about three times the distance between Earth and the moon. During the approach phase, the spacecraft's main activity will be thrusting with a special, hyper-efficient ion engine that uses electricity to ionize and accelerate xenon. The 12-inch-wide ion thrusters provide less thrust than conventional engines, but will provide propulsion for years during the mission and provide far greater capability to change velocity.

"We feel a little like Columbus approaching the shores of the New World," said Christopher Russell, Dawn principal investigator, based at the University of California in Los Angeles (UCLA). "The Dawn team can't wait to start mapping this Terra Incognita."

Dawn previously navigated by measuring the radio signal between the spacecraft and Earth, and used other methods that did not involve Vesta. But as the spacecraft closes in on its target, navigation requires more precise measurements. By analyzing where Vesta appears relative to stars, navigators will pin down its location and enable engineers to refine the spacecraft's trajectory. Using its ion engine to match Vesta's orbit around the sun, the spacecraft will spiral gently into orbit around the asteroid. When Dawn gets approximately 16,000 kilometers (9,900 miles) from Vesta, the asteroid's gravity will capture the spacecraft in orbit.

"After more than three-and-a-half years of interplanetary travel, we are finally closing in on our first destination," said Marc Rayman, Dawn's chief engineer, at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "We're not there yet, but Dawn will soon bring into focus an entire world that has been, for most of the two centuries scientists have been studying it, little more than a pinpoint of light."

Scientists will search the framing camera images for possible moons around Vesta. None of the images from ground-based and Earth-orbiting telescopes have seen any moons, but Dawn will give scientists much more detailed images to determine whether small objects have gone undiscovered.

The gamma ray and neutron detector instrument also will gather information on cosmic rays during the approach phase, providing a baseline for comparison when Dawn is much closer to Vesta. Simultaneously, Dawn's visible and infrared mapping spectrometer will take early measurements to ensure it is calibrated and ready when the spacecraft enters orbit around Vesta.

Dawn's odyssey, which will take it on a journey of 4.8-billion kilometers (3-billion miles), began on Sept. 27, 2007, with its launch from Cape Canaveral Air Force Station in Florida. It will stay in orbit around Vesta for one year. After another long cruise phase, Dawn will arrive at its second destination, an even more massive body in the asteroid belt, called Ceres, in 2015.

These two icons of the asteroid belt will help scientists unlock the secrets of our solar system's early history. The mission will compare and contrast the two giant bodies, which were shaped by different forces. Dawn's science instrument suite will measure surface composition, topography and texture. In addition, the Dawn spacecraft will measure the tug of gravity from Vesta and Ceres to learn more about their internal structures.

The Dawn mission to Vesta and Ceres is managed by JPL for NASA's Science Mission Directorate in Washington. Dawn is a project of SMD's Discovery Program, which is managed by NASA's Marshall Space Flight Center in Huntsville, Ala. UCLA is responsible for overall Dawn mission science. Orbital Sciences Corp. of Dulles, Va., designed and built the Dawn spacecraft. The framing cameras have been developed and built under the leadership of the Max Planck Institute for Solar System Research in Katlenburg-Lindau in Germany, with significant contributions by the German Aerospace Center (DLR) Institute of Planetary Research in Berlin, and in coordination with the Institute of Computer and Communication Network Engineering in Braunschweig. The framing camera project is funded by NASA, the Max Planck Society and DLR.

JPL is a division of the California Institute of Technology, Pasadena.

For more information visit http://www.nasa.gov/mission_pages/dawn/news/dawn20110503.html

"On November 8, asteroid 2005 YU55 will fly past Earth and at its closest approach point will be about 325,000 kilometers [201,700 miles] away," said Don Yeomans, manager of NASA's Near-Earth Object Program Office at the Jet Propulsion Laboratory in Pasadena, Calif. "This asteroid is about 400 meters [1,300 feet] wide – the largest space rock we have identified that will come this close until 2028."

Despite the relative proximity and size, Yeomans said, "YU55 poses no threat of an Earth collision over, at the very least, the next 100 years. During its closest approach, its gravitational effect on the Earth will be so miniscule as to be immeasurable. It will not affect the tides or anything else."

Then why all the hubbub for a space rock a little bit wider than an aircraft carrier? After all, scientists estimate that asteroids the size of YU55 come this close about every 25 years.

"While near-Earth objects of this size have flown within a lunar distance in the past, we did not have the foreknowledge and technology to take advantage of the opportunity," said Barbara Wilson, a scientist at JPL. "When it flies past, it should be a great opportunity for science instruments on the ground to get a good look."

2005 YU55 was discovered in December 2005 by Robert McMillan, head of the NASA-funded Spacewatch Program at the University of Arizona, Tucson. The space rock has been in astronomers' crosshairs before. In April 2010, Mike Nolan and colleagues at the Arecibo Observatory in Puerto Rico generated some ghostly images of 2005 YU55 when the asteroid was about 2.3 million kilometers (1.5 million miles) from Earth. See related story.

"The best resolution of the radar images was 7.5 meters [25 feet] per pixel," said JPL radar astronomer Lance Benner. "When 2005 YU55 returns this fall, we intend to image it at 4-meter resolution with our recently upgraded equipment at the Deep Space Network at Goldstone, California. Plus, the asteroid will be seven times closer. We're expecting some very detailed radar images."

Radar astronomy employs the world's most massive dish-shaped antennas. The antennas beam directed microwave signals at their celestial targets -- which can be as close as our moon and as far away as the moons of Saturn. These signals bounce off the target, and the resulting "echo" is collected and precisely collated to create radar images, which can be used to reconstruct detailed three-dimensional models of the object. This defines its rotation precisely and gives scientists a good idea of the object's surface roughness. They can even make out surface features.

"Using the Goldstone radar operating with the software and hardware upgrades, the resulting images of YU55 could come in with resolution as fine as 4 meters per pixel," said Benner. "We're talking about getting down to the kind of surface detail you dream of when you have a spacecraft fly by one of these targets."

At that resolution, JPL astronomers can see boulders and craters on the surfaces of some asteroids, and establish if an asteroid has a moon or two of its own. (Note: the 2010 Arecibo imaging of YU55 did not show any moons). But beyond the visually intriguing surface, the data collected from Goldstone, Arecibo, and ground-based optical and infrared telescopes are expected to detail the mineral composition of the asteroid.

"This is a C-type asteroid, and those are thought to be representative of the primordial materials from which our solar system was formed," said Wilson. "This flyby will be an excellent opportunity to test how we study, document and quantify which asteroids would be most appropriate for a future human mission."

Yeomans reiterated Wilson's view that the upcoming pass of asteroid 2005 YU55 will be a positive event, which he describes as an "opportunity for scientific discovery." Yeomans adds, "So stay tuned. This is going to be fun."

The 70-meter (230-foot) Goldstone antenna in California's Mojave Desert, part of NASA's Deep Space Network, is one of only two facilities capable of imaging asteroids with radar. The other is the National Science Foundation's 1,000-foot-diameter (305 meters) Arecibo Observatory in Puerto Rico. The capabilities of the two instruments are complementary. The Arecibo radar is about 20 times more sensitive and can detect asteroids about twice as far away, but because the main dish is stationary it can only see about one-third of the sky. Goldstone is fully steerable and can see about 80 percent of the accessible sky, so it can track objects several times longer per day and can image asteroids at finer spatial resolution. To date, Goldstone and Arecibo have observed 272 near-Earth asteroids and 14 comets with radar. JPL manages the Goldstone Solar System Radar and the Deep Space Network for NASA.

NASA detects, tracks and characterizes asteroids and comets passing close to Earth using both ground- and space-based telescopes. The Near-Earth Object Observations Program, commonly called "Spaceguard," discovers these objects, characterizes a subset of them, and plots their orbits to determine if any could be potentially hazardous to our planet.

JPL manages the Near-Earth Object Program Office for NASA's Science Mission Directorate in Washington. JPL is a division of the California Institute of Technology in Pasadena.

For more information visit http://www.nasa.gov/topics/solarsystem/features/asteroid20110502.html

Scheduled to launch April 29, 2011 with STS-134, the spider habitat will transfer from the space shuttle Endeavour to the space station. Once aboard, the crew will place the two habitats into the Commercial Generic Bioprocessing Apparatus or CGBA. This equipment will maintain a consistent temperature, humidity and lighting cycle for the spiders and their sustenance supply of fruit flies. The CGBA also controls imaging for the investigation.

The spider pair currently planned for investigation with CSI-05 are both golden orb spiders (Nephila clavipes), which spin a three dimensional, asymmetric web. This is different from the two orb spiders (Larinioides patagiatus and Metepeira) that launched to the space station on STS-126, which were selected specifically for the symmetry of their web formation. Scientists are looking to see if and how the arachnids will spin their webs differently in microgravity. The results will help them to understand the behavioral role of gravity for the spiders and their fruit fly companions.

“I think people can relate to everyday insects and they can understand why the experiment is of interest,” said Stefanie Countryman, coordinator for CSI-05. “Plus, the visual aspects of this experiment make it very appealing to the general public.”

When a sequel does top the original, in science as in movies, it usually has something to do with lessons learned during the first production. The CSI-03 investigation, for instance, was unfortunately restricted to eight days, due to the spiders’ fruit flies food ‘sliming’ the observation window. This obscured the view inside the habitat and limited the study. For CSI-05, which is funded by the National Space Biomedical Research Institute or NSBRI and the NASA National Lab Education Office, the fruit flies will have a separate compartment from the spiders. The crew will slowly introduce the flies—approximately every four days—into the two individual spider habitats, which should allow for clear imagery through the viewing window for the full 45-day duration of the investigation.

The fruit flies are not, however, simply nourishment for the spiders. They are actually a secondary study themselves. Scientists plan to look at their mobility over time to see if and how they react to the microgravity environment. They should be able to observe growth, behavioral and flight patterns as the flies develop.

There also is an important education element to this investigation, sponsored by Baylor College of medicine Center for Educational Outreach and Orion’s Quest. While the N. clavipes is spinning in space, students on Earth will develop and observe their own spider habitats. Teachers can use a curriculum found on bioedonline.org. This Web site includes daily images sent from the space station to the BioServe Payload Operations and Control Center. This allows students to compare their spiders’ spinning habits to those of the spiders in microgravity in near real time. Orion’s Quest Web site—orionsquest.org—will focus on the habits of the fruit flies in space.

For more information visit http://www.nasa.gov/mission_pages/station/research/news/space_spiders.html

"Collisions between asteroids create rock fragments, from fine dust to huge boulders, that impact planets and their moons," said Dennis Bodewits, an astronomer at the University of Maryland in College Park and lead author of the Swift study. "Yet this is the first time we've been able to catch one just weeks after the smash-up, long before the evidence fades away."

Asteroids are rocky fragments thought to be debris from the formation and evolution of the solar system approximately 4.6 billion years ago. Millions of them orbit the sun between Mars and Jupiter in the main asteroid belt. Scheila is approximately 70 miles across and orbits the sun every five years.

"The Hubble data are most simply explained by the impact, at 11,000 mph, of a previously unknown asteroid about 100 feet in diameter," said Hubble team leader David Jewitt at the University of California in Los Angeles. Hubble did not see any discrete collision fragments, unlike its 2009 observations of P/2010 A2, the first identified asteroid collision.

The studies will appear in the May 20 edition of The Astrophysical Journal Letters and are available online.

Astronomers have known for decades that comets contain icy material that erupts when warmed by the sun. They regarded asteroids as inactive rocks whose destinies, surfaces, shapes and sizes were determined by mutual impacts. However, this simple picture has grown more complex over the past few years.

During certain parts of their orbits, some objects, once categorized as asteroids, clearly develop comet-like features that can last for many months. Others display much shorter outbursts. Icy materials may be occasionally exposed, either by internal geological processes or by an external one, such as an impact.

On Dec. 11, 2010, images from the University of Arizona's Catalina Sky Survey, a project of NASA's Near Earth Object Observations Program, revealed Scheila to be twice as bright as expected and immersed in a faint comet-like glow. Looking through the survey's archived images, astronomers inferred the outburst began between Nov. 11 and Dec. 3.

Three days after the outburst was announced, Swift's Ultraviolet/Optical Telescope (UVOT) captured multiple images and a spectrum of the asteroid. Ultraviolet sunlight breaks up the gas molecules surrounding comets; water, for example, is transformed into hydroxyl and hydrogen. But none of the emissions most commonly identified in comets, such as hydroxyl or cyanogen, show up in the UVOT spectrum. The absence of gas around Scheila led the Swift team to reject scenarios where exposed ice accounted for the activity.

Images show the asteroid was flanked in the north by a bright dust plume and in the south by a fainter one. The dual plumes formed as small dust particles excavated by the impact were pushed away from the asteroid by sunlight. Hubble observed the asteroid's fading dust cloud on Dec. 27, 2010, and Jan. 4, 2011.

The two teams found the observations were best explained by a collision with a small asteroid impacting Scheila's surface at an angle of less than 30 degrees, leaving a crater 1,000 feet across. Laboratory experiments show a more direct strike probably wouldn't have produced two distinct dust plumes. The researchers estimated the crash ejected more than 660,000 tons of dust -- equivalent to nearly twice the mass of the Empire State Building.

"The dust cloud around Scheila could be 10,000 times as massive as the one ejected from comet 9P/Tempel 1 during NASA's UMD-led Deep Impact mission," said co-author Michael Kelley, also at the University of Maryland. "Collisions allow us to peek inside comets and asteroids. Ejecta kicked up by Deep Impact contained lots of ice, and the absence of ice in Scheila's interior shows that it's entirely unlike comets."

NASA's Goddard Space Flight Center in Greenbelt, Md., manages Hubble and Swift. Hubble was built and is operated in partnership with the European Space Agency. Science operations for both missions include contributions from many national and international partners.

For more information visit http://www.nasa.gov/topics/universe/features/asteroid-collision.html

The tracks are pale brown trails where green trees and plants have been uprooted, leaving disturbed ground. Though faint, the center track runs from southwest of Tuscaloosa, through the gray city, and extends northeast towards Birmingham. Two other tracks run parallel to the center track. The northernmost track is in an area where the National Weather Service reported a tornado, but no tornado was reported in the vicinity of the more visible southern track. In the southern region, strong winds were reported.

The tornadoes were part of a larger weather pattern that produced more than 150 tornadoes across six states, said the National Weather Service. The death toll had nearly reached 300 on April 29, making the outbreak the deadliest in the United States since 1974.

For more information visit http://www.nasa.gov/topics/earth/features/severe-storms-20110429.html

"It's inspiring to learn that STEREO, which was designed to teach us more about the Sun's influence on our solar system, is able to detect other solar systems," said STEREO project scientist Joseph Gurman at NASA's Goddard Space Flight Center in Greenbelt, Md.

Although STEREO is primarily a solar mission, the team realized that the stability of the Heliospheric Imagers (HI) aboard the twin spacecraft could be used to monitor variations in the brightness of stars.

"STEREO's Heliospheric Imagers were designed for stable, accurate measurements to allow us to subtract out the stellar background and see faint coronal mass ejections --- but that same stability allows us to make the incredibly precise measurements necessary to detect such small changes in the brightness of stars,” Gurman remarked.

According to one of the leads in this survey, STEREO's ability to sample continuously for up to 20 days, coupled with repeat viewings from the spacecraft during the year, makes it an invaluable resource for researching variable stars. Observations from the HI cameras are enabling scientists to pin down the periods of known variables with much greater accuracy.

In addition to studying variable stars, the U.K. team announced that HI measurements may be useful for exoplanet and astroseismology research. Very small changes to the brightness of stars can be detected, which could reveal the presence of transiting exoplanets, or trace a star’s internal structure by measuring their seismic activity.

Teams from the Open University, University of Central Lancashire and the Science and Technologies Facilities Council Rutherford Appleton Laboratory carried out the study and their findings were presented at the Royal Astronomical Society’s National Astronomy Meeting in Llandudno, Wales, on April 19.

STEREO is the third mission in NASA's Solar Terrestrial Probes program. The mission, launched in October 2006, has provided a unique and revolutionary view of the Sun-Earth System. The two nearly identical observatories - one ahead of Earth in its orbit, the other trailing behind - have traced the flow of energy and matter from the sun to Earth. STEREO is also key to the fleet of space weather detection satellites by providing more accurate alerts for the arrival time of Earth-directed solar ejections with its unique side-viewing perspective.

For more information visit http://www.nasa.gov/mission_pages/stereo/news/binary-stars.html

The event will be held at NASA Headquarters in Washington and will be broadcast live on NASA Television and streamed at http://www.nasa.gov . In addition, the event will be carried live on Ustream, with a live chat box available, at http://www.ustream.tv/nasajpl2 .

After 33 years in space, the spacecraft are still operating and returning data from about 16 billion kilometers (10 billion miles) away from our sun. The Voyagers also carry a collection of images and sounds from Earth as a message to possible life elsewhere in the galaxy.

The participants are:
-- Ed Stone, Voyager project scientist and professor of physics, California Institute of Technology, Pasadena, Calif.
-- Ann Druyan, creative director, Voyager Interstellar Message Project; Carl Sagan's co-author and widow
-- Suzanne Dodd, Voyager project manager, NASA’s Jet Propulsion Laboratory, Pasadena, Calif.
-- Merav Opher, Voyager guest investigator and assistant professor of astronomy, Boston University

For more information visit http://www.nasa.gov/mission_pages/voyager/voyager20110426.html

"For 21 years, Hubble has profoundly changed our view of the universe, allowing us to see deep into the past while opening our eyes to the majesty and wonders around us," NASA Administrator Charles Bolden said."I was privileged to pilot space shuttle Discovery as it deployed Hubble. After all this time, new Hubble images still inspire awe and are a testament to the extraordinary work of the many people behind the world's most famous observatory."

Hubble was launched April 24, 1990, aboard Discovery's STS-31 mission. Hubble discoveries revolutionized nearly all areas of current astronomical research from planetary science to cosmology.

"Hubble is America's gift to the world," Sen. Barbara Mikulski of Maryland said. "Its jaw-dropping images have rewritten the textbooks and inspired generations of schoolchildren to study math and science. It has been documenting the history of our universe for 21 years. Thanks to the daring of our brave astronauts, a successful servicing mission in 2009 gave Hubble new life. I look forward to Hubble's amazing images and inspiring discoveries for years to come."

The newly released Hubble image shows a large spiral galaxy, known as UGC 1810, with a disk that is distorted into a rose-like shape by the gravitational tidal pull of the companion galaxy below it, known as UGC 1813. A swath of blue jewel-like points across the top is the combined light from clusters of intensely bright and hot young blue stars. These massive stars glow fiercely in ultraviolet light.

The smaller, nearly edge-on companion shows distinct signs of intense star formation at its nucleus, perhaps triggered by the encounter with the companion galaxy.

Arp 273 lies in the constellation Andromeda and is roughly 300 million light-years away from Earth. The image shows a tenuous tidal bridge of material between the two galaxies that are separated from each other by tens of thousands of light-years.

A series of uncommon spiral patterns in the large galaxy are a tell-tale sign of interaction. The large, outer arm appears partially as a ring, a feature seen when interacting galaxies actually pass through one another. This suggests the smaller companion dived deep, but off-center, through UGC 1810. The inner set of spiral arms is highly warped out of the plane, with one of the arms going behind the bulge and coming back out the other side. How these two spiral patterns connect is not precisely known.

The larger galaxy in the UGC 1810 - UGC 1813 pair has a mass about five times that of the smaller galaxy. In unequal pairs such as this, the relatively rapid passage of a companion galaxy produces the lopsided or asymmetric structure in the main spiral. Also in such encounters, the starburst activity typically begins in the minor galaxies earlier than in the major galaxies. These effects could be because the smaller galaxies have consumed less of the gas present in their nuclei, from which new stars are born.

The interaction was imaged on Dec. 17, 2010, with Hubble's Wide Field Camera 3 (WFC3). The picture is a composite of data taken with three separate filters on WFC3 that allow a broad range of wavelengths covering the ultraviolet, blue, and red portions of the spectrum.

The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA's Goddard Space Flight Center manages the telescope. The Space Telescope Science Institute (STScI) conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy Inc. in Washington, D.C.

For more information visit http://www.nasa.gov/mission_pages/hubble/science/hubble-rose.html

Researchers using the orbiter's ground-penetrating radar identified a large, buried deposit of frozen carbon dioxide, or dry ice, at the Red Planet's south pole. The scientists suspect that much of this carbon dioxide enters the planet's atmosphere and swells the atmosphere's mass when Mars' tilt increases. The findings are published in this week's issue of the journal Science.

The newly found deposit has a volume similar to Lake Superior's nearly 3,000 cubic miles (about 12,000 cubic kilometers). The deposit holds up to 80 percent as much carbon dioxide as today's Martian atmosphere. Collapse pits caused by dry ice sublimation and other clues suggest the deposit is in a dissipating phase, adding gas to the atmosphere each year. Mars' atmosphere is about 95 percent carbon dioxide, in contrast to Earth's much thicker atmosphere, which is less than .04 percent carbon dioxide.

"We already knew there is a small perennial cap of carbon-dioxide ice on top of the water ice there, but this buried deposit has about 30 times more dry ice than previously estimated," said Roger Phillips of Southwest Research Institute in Boulder, Colo. Phillips is deputy team leader for the Mars Reconnaissance Orbiter's Shallow Radar instrument and lead author of the report.

"We identified the deposit as dry ice by determining the radar signature fit the radio-wave transmission characteristics of frozen carbon dioxide far better than the characteristics of frozen water," said Roberto Seu of Sapienza University of Rome, team leader for the Shallow Radar and a co-author of the new report. Additional evidence came from correlating the deposit to visible sublimation features typical of dry ice.

"When you include this buried deposit, Martian carbon dioxide right now is roughly half frozen and half in the atmosphere, but at other times it can be nearly all frozen or nearly all in the atmosphere," Phillips said.

An occasional increase in the atmosphere would strengthen winds, lofting more dust and leading to more frequent and more intense dust storms. Another result is an expanded area on the planet's surface where liquid water could persist without boiling. Modeling based on known variation in the tilt of Mars' axis suggests several-fold changes in the total mass of the planet's atmosphere can happen on time frames of 100,000 years or less.

The changes in atmospheric density caused by the carbon-dioxide increase also would amplify some effects of the changes caused by the tilt. Researchers plugged the mass of the buried carbon-dioxide deposit into climate models for the period when Mars' tilt and orbital properties maximize the amount of summer sunshine hitting the south pole. They found at such times, global, year-round average air pressure is approximately 75 percent greater than the current level.

"A tilted Mars with a thicker carbon-dioxide atmosphere causes a greenhouse effect that tries to warm the Martian surface, while thicker and longer-lived polar ice caps try to cool it," said co-author Robert Haberle, a planetary scientist at NASA's Ames Research Center in Moffett Field, Calif. "Our simulations show the polar caps cool more than the greenhouse warms. 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."

The Shallow Radar, one of the Mars Reconnaissance Orbiter's six instruments, was provided by the Italian Space Agency, and its operations are led by the Department of Information Engineering, Electronics and Telecommunications at Sapienza University of Rome. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Mars Reconnaissance Orbiter project for NASA's Science Mission Directorate at the agency's headquarters in Washington. Lockheed Martin Space Systems in Denver built the spacecraft.

For more information visit http://www.nasa.gov/mission_pages/MRO/news/mro20110421.html

"The formation of the clouds requires both water and incredibly low temperatures," says Charles Jackman, an atmospheric scientist at NASA's Goddard Space Flight Center in Greenbelt, Md., who is NASA's project scientist for AIM. "The temperatures turn out to be one of the prime driving factors for when the clouds appear."

So the appearance of the noctilucent clouds, also known as polar mesospheric clouds or PMCs since they occur in a layer of the atmosphere called the mesosphere, can provide information about the temperature and other characteristics of the atmosphere. This in turn, helps researchers understand more about Earth's low altitude weather systems, and they've discovered that events in one hemisphere can have a sizable effect in another.

Since these mysterious clouds were first spotted, researchers have learned much about them. They light up because they're so high that they reflect sunlight from over the horizon. They are formed of ice water crystals most likely created on meteoric dust. And they are exclusively a summertime phenomenon.

"The question people usually ask is why do clouds which require such cold temperatures form in the summer?" says James Russell, an atmospheric scientist at Hampton University in Hampton, Va., who is the Principal Investigator for AIM. "It's because of the dynamics of the atmosphere. You actually get the coldest temperatures of the year near the poles in summer at that height in the mesosphere."

As summer warmth heats up air near the ground, the air rises. As it rises, it also expands since atmospheric pressure decreases with height. Scientists have long known that such expansion cools things down – just think of how the spray out of an aerosol can feels cold – and this, coupled with dynamics in the atmosphere that drives the cold air even higher, brings temperatures in the mesosphere down past a freezing -210º F (-134 ºC).

In the Northern hemisphere, the mesosphere reaches these temperatures consistently by the middle of May. Since AIM has been collecting data, the onset of the Northern season has never varied by more than a week or so. But the southern hemisphere turns out to be highly variable. Indeed, the 2010 season started nearly a month later than the 2009 season.

Atmospheric scientist Bodil Karlsson, a member of the AIM team, has been analyzing why the start of the southern noctilucent cloud season can vary so dramatically. Karlsson is a researcher at Stockholm University in Sweden, though until recently she worked as a post-doctoral researcher at the University of Colorado. A change in when some pretty clouds show up may not seem like much all by itself, but it's a tool for mapping the goings-on in the atmosphere, says Karlsson.

"Since the clouds are so sensitive to the atmospheric temperatures," says Karlsson. "They can act as a proxy for information about the wind circulation that causes these temperatures. They can tell us that the circulation exists first of all, and tell us something about the strength of the circulation."

She says the onset of the clouds is timed to something called the southern stratospheric vortex – a winter wind pattern that circles above the pole. In 2010, that vortex lingered well into the southern summer season, keeping the lower air cold and interfering with cloud formation. This part of the equation is fairly straightforward and Karlsson has recently submitted a paper on the subject to the Journal of Geophysical Research. But this is not yet the complete answer to what drives the appearance of these brightly lit clouds.

AIM researchers also believe there is a connection between seemingly disparate atmospheric patterns in the north and south. The upwelling of polar air each summer that contributes to noctilucent cloud formation is part of a larger circulation loop that travels between the two poles. So wind activity some 13,000 miles (20,920 km) away in the northern hemisphere appears to be influencing the southern circulation.

The first hints that wind in the north and south poles were coupled came in 2002 and 2003 when researchers noticed that despite a very calm lower weather system near the southern poles in the summer, the higher altitudes showed variability. Something else must be driving that change.

Now, AIM's detailed images of the clouds have enabled researchers to look at even day-to-day variability. They've spotted a 3 to10 day time lag between low-lying weather events in the north – an area that, since it is fairly mountainous, is prone to more complex wind patterns – and weather events in the mesosphere in the south. On the flip side, the lower atmosphere at the southern poles has little variability, and so the upper atmosphere where the clouds form at the northern poles stays fairly constant. Thus, there's a consistent start to the cloud season each year.

"The real importance of all of that," says Hampton's Russell, "is not only that events down where we live can affect the clouds 50 miles (80 km) above, but that the total atmosphere from one pole to the next is rather tightly connected."

Hammering out the exact mechanisms of that connection will, of course, take more analysis. The noctilucent cloud season will also surely be affected by the change in heat output from the sun during the upcoming solar maximum. Researchers hope to use the clouds to understand how the sun's cycle affects the Earth's atmosphere and the interaction between natural- and humankind-caused changes.

"These are the highest clouds in Earth's atmosphere, formed in the coldest place in Earth's atmosphere," says Goddard's Jackman. "Although the clouds occur only in the polar summer, they help us to understand more about the whole globe."

AIM is a NASA-funded Small Explorers (SMEX) mission. NASA Goddard manages the program for the agency's Science Mission Directorate at NASA headquarters in Washington. The mission is led by the Principal Investigator from the Center for Atmospheric Sciences at Hampton University in Virginia. The Laboratory for Atmospheric and Space Physics (LASP), University of Colorado, Boulder, and the Space Dynamics Laboratory, Utah State University, built the instruments. LASP also manages the mission and controls the satellite.

For more information visit http://www.nasa.gov/mission_pages/aim/news/notilucent-change.html

"I'm extremely pleased to receive all these honors, which reflect the groundbreaking research and projects I've had the opportunity to work on with my colleagues at Caltech, JPL and NASA through the years," Elachi said.

This week, Elachi accepted the 2011 General James E. Hill Lifetime Space Achievement Award from the Space Foundation. The award was presented at the National Space Symposium in Colorado Springs, Colo.

The award, named for the Space Foundation's former chairman, Gen. James E. Hill, USAF (retired), recognizes "outstanding individuals who have distinguished themselves through lifetime contributions to the welfare or betterment of humankind through exploration, development and use of space, or through use of space technology, information, themes or resources in academic, cultural, industrial or other pursuits of broad benefit to humanity."

On March 5, Elachi was presented with an honorary doctor of science degree by Occidental College in Los Angeles during its 40th annual President's Circle Dinner at JPL. Also in March, he received the American Astronautical Society's 2011 Carl Sagan Memorial Award at the organization's symposium in Greenbelt, Md. The award, presented in cooperation with the Planetary Society, is given to individuals who demonstrate leadership in research or policies advancing exploration of the cosmos.

In addition to the trio of awards he has accepted in the United States this year, Elachi is receiving two international honors.

He is being inducted into the French Legion, known as the Chevalier de la Legion d'Honneur. Although Elachi is a native of Lebanon, and the award is traditionally restricted to natives of France, the honor has been bestowed on foreign nationals "who have served France or the ideals it upholds." Being honored at age 16 as Lebanon's top science student enabled Elachi to attend the college of his choice, France's University of Grenoble, where he earned a bachelor's degree in physics in 1968. That same year, he received an engineering degree from the Polytechnic Institute in Grenoble, where he graduated first in the class.

"I'm very honored to be recognized with such a prestigious award," said Elachi, who will formally accept the honor for his life's work at a ceremony in the near future. "The years I spent in France, at the University of Grenoble and the Polytechnic Institute in Grenoble, were an important part of my life and helped pave the way for my career."

After studying in France, Elachi moved to Pasadena, where he received a master's (1969) and Ph.D. (1971) in electrical sciences from the California Institute of Technology. He also earned a master's degree (1983) in geology from UCLA and an MBA (1979) from USC.

Elachi noted that throughout his career, his links to France have continued through his research.

He joined JPL in 1970 as a researcher on various Earth and planetary missions. Elachi has been serving as JPL director since May 2001, and the decade since then has included such successful NASA space missions as the Mars Exploration Rovers Spirit and Opportunity, the Phoenix Mars Lander, Stardust, Spitzer, Kepler, and such Earth-orbiting satellites as Grace and Topex/Poseidon-Jason.

"Over the last three decades, JPL and the French Space Agency, working together, have revolutionized the field of oceanography by developing the capability to observe and monitor ocean currents on a global basis from space," Elachi said.

In addition to serving as JPL director, Elachi is vice president of Caltech, and an electrical engineering and planetary science professor. Caltech manages JPL for NASA.

Elachi has recently been listed in the top 10 on the Arabian Business Magazine "Power 500" list of the world's most influential people of Arab descent. The award looks at the influence of people from the Middle East in every sector: from the business world, media, entertainment, sports, science, arts and academia. Elachi is described as "one person who has driven mankind's thirst for knowledge about the other planets in our solar system."

For more information visit http://www.nasa.gov/topics/people/features/elachi20110419.html

"The Primary mirror EDU will be used next year to check out optical test equipment developed by Goddard and slated to be used to test the full Flight Primary mirror," said Lee Feinberg, the Optical Telescope Element Manager for the Webb telescope at NASA Goddard. "Following that, the primary and secondary EDU's will actually be assembled onto the Pathfinder telescope. The Pathfinder telescope includes two primary mirror segments (one being the Primary EDU) and the Secondary EDU and allows us to check out all of the assembly and test procedures (that occur both at Goddard and testing at Johnson Space Center, Houston, Texas) well in advance of the flight telescope assembly and test."

The primary mirror is actually composed of 18 smaller hexagonal mirrors that are assembled together into what appears to be a giant hexagon that sits atop the Webb telescope's sunshield. Webb Telescope's scientists and engineers determined that a primary mirror measuring 6.5 meters (21 feet 4 inches) across is what was needed to measure the light from these distant galaxies. Each of these mirrors is constructed from beryllium, a light and strong metal. Each of the 18 mirror segments weighs approximately 20 kilograms (46 pounds).

Why are the mirrors hexagonal shaped? Because a hexagon allows a segmented mirror to fit together without gaps. When Webb's primary mirror is focused on a distant star for example, that image will appear in all 18 mirror segments. To focus on the star and get one image, the mirror segments can then be tilted to align the 18 separate images into a single image.

Although there are 18 segments, there are three different optical prescriptions for the 18 segments: six segments of each prescription. The segment received is the first of the "A" prescription segments for which a total of 7 will be made - 6 flight and 1 spare. A prescription is similar to an eyeglass prescription and specifies a unique mirror curvature. Like eyeglasses, mirrors with the same prescription are interchangeable.

The primary mirror EDU that arrived at Goddard is also a flight spare. That means it can be used on the actual telescope. In fact, it could even be put on the telescope now if needed.

The primary mirror segment has already been cleaned and coated. Ball Aerospace & Technologies cleaned the mirror segment and Quantum Coating, Inc., in Moorestown, N.J., coated it. Ball Aerospace then took the mirror segment back, reassembled it with mounts and actuators and conducted final vibration testing.

Afterward, the mirror segment went back to the X-ray and Cryogenic Facility (XRCF) in Huntsville, Ala., where Ball performed final cryogenic acceptance testing on the segment before it came to NASA Goddard.

The secondary mirror on the Webb telescope will direct the light from the primary mirror to where it can be collected by the Webb's instruments. The secondary mirror is connected to "arms" that position it in front of the 18 primary mirror segments. It will focus all of the light from the 18 primary mirrors.

The secondary EDU at Goddard is not coated but can be, so it can be a flight spare once coated.

Eventually, the final flight mirrors will all come to NASA Goddard and be assembled on the telescope and the instrument module. Then, as a complete unit it will undergo acoustic and vibration testing at Goddard.

The James Webb Space Telescope is the world’s next-generation space observatory and successor to the Hubble Space Telescope. The most powerful space telescope ever built, Webb will observe the most distant objects in the universe, provide images of the very first galaxies ever formed and see unexplored planets around distant stars. The Webb Telescope is a joint project of NASA, the European Space Agency and the Canadian Space Agency.

For more information visit http://www.nasa.gov/topics/technology/features/two-webb-mirrors.html

Back in 2008, the solar cycle plunged into the deepest minimum in nearly a century. Sunspots all but vanished, solar flares subsided, and the sun was eerily quiet.

"Ever since, we've been waiting for solar activity to pick up," says Richard Fisher, head of the Heliophysics Division at NASA Headquarters in Washington DC. "It's been three long years."

Quiet spells on the sun are nothing new. They come along every 11 years or so—it's a natural part of the solar cycle. This particular solar minimum, however, was lasting longer than usual, prompting some researchers to wonder if it would ever end.

News flash: The pot is starting to boil. "Finally," says Fisher, "we are beginning to see some action."

As 2011 unfolds, sunspots have returned and they are crackling with activity. On February 15th and again on March 9th, Earth orbiting satellites detected a pair of "X-class" solar flares--the most powerful kind of x-ray flare. The last such eruption occurred back in December 2006.

Another eruption on March 7th hurled a billion-ton cloud of plasma away from the sun at five million mph (2200 km/s). The rapidly expanding cloud wasn't aimed directly at Earth, but it did deliver a glancing blow to our planet's magnetic field. The off-center impact on March 10th was enough to send Northern Lights spilling over the Canadian border into US states such as Wisconsin, Minnesota, and Michigan.

"That was the fastest coronal mass ejection in almost six years," says Angelos Vourlidas of the Naval Research Lab in Washington DC. "It reminds me of a similar series of events back in Nov. 1997 that kicked off Solar Cycle 23, the solar cycle before this one."

"To me," says Vourlidas, "this marks the beginning of Solar Cycle 24."

The slow build-up to this moment is more than just "the watched pot failing to boil," says Ron Turner, a space weather analyst at Analytic Services, Inc. "It really has been historically slow."

There have been 24 numbered solar cycles since researchers started keeping track of them in the mid-18th century. In an article just accepted for publication by the Space Weather Journal, Turner shows that, in all that time, only four cycles have started more slowly than this one. "Three of them were in the Dalton Minimum, a period of depressed solar activity in the early 19th century. The fourth was Cycle #1 itself, around 1755, also a relatively low solar cycle," he says.

In his study, Turner used sunspots as the key metric of solar activity. Folding in the recent spate of sunspots does not substantially alter his conclusion: "Solar Cycle 24 is a slow starter," he says.

Better late than never.

For more information visit http://www.nasa.gov/mission_pages/sunearth/news/watchedpot-fastCME.html