This visible image of Tropical Storm Arthur was taken by the MODIS instrument aboard NASA’s Aqua satellite on July 2 at 18:50 UTC (2:50 p.m. EDT). A cloud-covered eye is clearly visible. Image Credit: NASA Goddard MODIS Rapid Response Team
When NASA’s Aqua satellite passed over Tropical Storm Arthur on July 2 at 2:50 p.m. EDT on July 2, it saw a cloud-covered eye as the storm was on the way to becoming a hurricane.
This visible image of Tropical Storm Arthur was captured by the Moderate Resolution Imaging Spectroradiometer or MODIS instrument that flies aboard NASA’s Aqua satellite. Arthur’s center was over the Atlantic Ocean and east of Florida’s northeast coast. By 5 a.m. EDT on July 3, Arthur’s eye had formed but remained cloud covered even as the storm hit hurricane-strength with maximum sustained winds near 75 mph.
The Atmospheric Infrared Sounder or AIRS instrument aboard NASA’s Aqua satellite captured infrared data on Tropical Storm Arthur’s cloud tops on July 3 at 2:47 p.m. EDT. The data was made into a false-colored infrared image at NASA’s Jet Propulsion Laboratory in Pasadena, California. The image showed powerful thunderstorms around Arthur’s center with temperatures near -63F/-53C. Cloud tops that cold tower to the near the top of the troposphere and have the ability to produce heavy rainfall.
By 8 a.m. EDT on July 3, watches and warnings peppered the U.S. Southeast. The National Hurricane Center or NHC issued the following: a hurricane warning is in effect for Surf City, North Carolina to the North Carolina/Virginia Border, Pamlico Sound and the Eastern Albemarle Sound. A hurricane watch is in effect for the Little River Inlet to south of Surf City. In addition, a tropical storm warning is in effect for South Santee River, South Carolina to south of Surf City; the North Carolina/Virginia border to Cape Charles Light; and Virginia, including the mouth of the Chesapeake Bay; and the Western Albemarle Sound.
On July 3 at 8 a.m. EDT (1200 UTC) the center of Hurricane Arthur was near latitude 31.8 north and longitude 78.7 west. That puts Arthur’s center about 300 miles (480 km) southwest of Cape Hatteras, North Carolina, and just 150 miles (240 km) south-southwest of Cape Fear, North Carolina. Maximum sustained winds have increased to near 80 mph (130 kph) and some additional strengthening is forecast during the next 24 hours.
The National Hurricane Center noted that Arthur is moving toward the north-northeast near 9 mph (15 kph and a turn to the northeast is expected. Arthur’s center is expected to approach the coast in the hurricane warning area tonight, July 3.
Forecaster Brennan noted in the July 3 discussion on Arthur that after moving very close to the North Carolina Outer Banks late on July 3 and early July 4, the storm should then accelerate northeastward offshore of the mid-Atlantic states and the northeastern U.S. on July 4. By July 5, the NHC expects Arthur to move into the Canadian Maritimes.
Curiosity on Mars Photo credit: Curiosity Courtesy of NASA
NASA’s Curiosity rover will mark one year on Mars next week and has already achieved its main science goal of revealing ancient Mars could have supported life. The mobile laboratory also is guiding designs for future planetary missions.
Charles Bolden and Elon Musk Photo courtesy of NASA
“Successes of our Curiosity — that dramatic touchdown a year ago and the science findings since then — advance us toward further exploration, including sending humans to an asteroid and Mars,” said NASA Administrator Charles Bolden. “Wheel tracks now, will lead to boot prints later.”
After inspiring millions of people worldwide with its successful landing in a crater on the Red Planet on Aug. 6, 2012 (Aug. 5, 2012, PDT), Curiosity has provided more than 190 gigabits of data; returned more than 36,700 full images and 35,000 thumbnail images; fired more than 75,000 laser shots to investigate the composition of targets; collected and analyzed sample material from two rocks; and driven more than one mile (1.6 kilometers).
Curiosity team members at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, Calif.,will share remembrances about the dramatic landing night and the mission overall in an event that will air on NASA Television and the agency’s website from 10:45 a.m. to noon EDT (7:45 to 9 a.m. PDT) on Tuesday, Aug. 6.
Immediately following that program, from noon to 1:30 p.m., NASA TV will carry a live public event from NASA Headquarters in Washington. That event will feature NASA officials and crew members aboard the International Space Station as they observe the rover anniversary and discuss how its activities and other robotic projects are helping prepare for a human mission to Mars and an asteroid. Social media followers may submit questions on Twitter and Google+ in advance and during the event using the hashtag #askNASA.
Curiosity, which is the size of a car, traveled 764 yards (699 meters) in the past four weeks since leaving a group of science targets where it worked for more than six months The rover is making its way to the base of Mount Sharp, where it will investigate lower layers of a mountain that rises three miles from the floor of the crater.
NASA’s Mars Science Laboratory spacecraft and its unprecedented sky crane landing system placed Curiosity on Mars near the base of Mount Sharp. The mountain has exposed geological layers, including ones identified by Mars orbiters as originating in a wet environment. The rover landed about one mile (1.6 kilometers) from the center of that carefully chosen, 12-mile-long (20 kilometers) target area.
Scientists decided first to investigate closer outcrops where the mission quickly found signs of vigorous ancient stream flow. These were the first streambed pebble deposits ever examined up close on Mars.
Evidence of a past environment well suited to support microbial life came within the first eight months of the 23-month primary mission from analysis of the first sample material ever collected by drilling into a rock on Mars.
“We now know Mars offered favorable conditions for microbial life billions of years ago,” said the mission’s project scientist, John Grotzinger of the California Institute of Technology in Pasadena. “It has been gratifying to succeed, but that has also whetted our appetites to learn more. We hope those enticing layers at Mount Sharp will preserve a broad diversity of other environmental conditions that could have affected habitability.”
The mission measured natural radiation levels on the trip to Mars and is monitoring radiation and weather on the surface of Mars, which will be helpful for designing future human missions to the planet. The Curiosity mission also found evidence Mars lost most of its original atmosphere through processes that occurred at the top of the atmosphere. NASA’s next mission to Mars, Mars Atmosphere and Volatile Evolution (MAVEN), is being prepared for launch in November to study those processes in the upper atmosphere.
JPL manages the Curiosity mission and built the rover for NASA’s Science Mission Directorate in Washington.
To follow the conversation online about Curiosity’s first year on Mars, use hashtag #1YearOnMars or follow @NASA and @MarsCuriosity on Twitter.
For NASA TV streaming video, schedule and downlink information, http://www.nasa.gov/ntv
A movie made with Hazard-Avoidance Camera images from Curiosity’s first year, titled “Twelve Months in Two Minutes,” is available at: http://mars.nasa.gov/msl/1yearin2mins
Artist concept of NASA’s Voyager spacecraft. Image Credit: NASA/JPL-Caltech
PASADENA, Calif. — Data from Voyager 1, now more than 11 billion miles (18 billion kilometers) from the sun, suggest the spacecraft is closer to becoming the first human-made object to reach interstellar space.
Research using Voyager 1 data and published in the journal Science today (6-27-13) provides new detail on the last region the spacecraft will cross before it leaves the heliosphere, or the bubble around our sun, and enters interstellar space. Three papers describe how Voyager 1′s entry into a region called the magnetic highway resulted in simultaneous observations of the highest rate so far of charged particles from outside heliosphere and the disappearance of charged particles from inside the heliosphere.
Scientists have seen two of the three signs of interstellar arrival they expected to see: charged particles disappearing as they zoom out along the solar magnetic field, and cosmic rays from far outside zooming in. Scientists have not yet seen the third sign, an abrupt change in the direction of the magnetic field, which would indicate the presence of the interstellar magnetic field.
(9-5-12) As part of a celebration of 35 years of flight for NASA’s Voyager spacecraft, a crowd of engineers and scientists at NASA’s Jet Propulsion Laboratory in Pasadena, Calif., gather at von Karman auditorium to listen to insider stories about Voyager. At the top right of the picture is a full-size model of Voyager. Image credit: NASA/JPL-Caltech Courtesy of NASA/JPL
“This strange, last region before interstellar space is coming into focus, thanks to Voyager 1, humankind’s most distant scout,” said Ed Stone, Voyager project scientist at the California Institute of Technology in Pasadena. “If you looked at the cosmic ray and energetic particle data in isolation, you might think Voyager had reached interstellar space, but the team feels Voyager 1 has not yet gotten there because we are still within the domain of the sun’s magnetic field.”
Scientists do not know exactly how far Voyager 1 has to go to reach interstellar space. They estimate it could take several more months, or even years, to get there. The heliosphere extends at least 8 billion miles (13 billion kilometers) beyond all the planets in our solar system. It is dominated by the sun’s magnetic field and an ionized wind expanding outward from the sun. Outside the heliosphere, interstellar space is filled with matter from other stars and the magnetic field present in the nearby region of the Milky Way.
Voyager 1 and its twin spacecraft, Voyager 2, were launched in 1977. They toured Jupiter, Saturn, Uranus and Neptune before embarking on their interstellar mission in 1990. They now aim to leave the heliosphere. Measuring the size of the heliosphere is part of the Voyagers’ mission.
The Science papers focus on observations made from May to September 2012 by Voyager 1′s cosmic ray, low-energy charged particle and magnetometer instruments, with some additional charged particle data obtained through April of this year.
Voyager 2 is about 9 billion miles (15 billion kilometers) from the sun and still inside the heliosphere. Voyager 1 was about 11 billion miles (18 billion kilometers) from the sun Aug. 25 when it reached the magnetic highway, also known as the depletion region, and a connection to interstellar space. This region allows charged particles to travel into and out of the heliosphere along a smooth magnetic field line, instead of bouncing around in all directions as if trapped on local roads. For the first time in this region, scientists could detect low-energy cosmic rays that originate from dying stars.
“We saw a dramatic and rapid disappearance of the solar-originating particles. They decreased in intensity by more than 1,000 times, as if there was a huge vacuum pump at the entrance ramp onto the magnetic highway,” said Stamatios Krimigis, the low-energy charged particle instrument’s principal investigator at the Johns Hopkins University Applied Physics Laboratory in Laurel, Md. “We have never witnessed such a decrease before, except when Voyager 1 exited the giant magnetosphere of Jupiter, some 34 years ago.”
Other charged particle behavior observed by Voyager 1 also indicates the spacecraft still is in a region of transition to the interstellar medium. While crossing into the new region, the charged particles originating from the heliosphere that decreased most quickly were those shooting straightest along solar magnetic field lines. Particles moving perpendicular to the magnetic field did not decrease as quickly. However, cosmic rays moving along the field lines in the magnetic highway region were somewhat more populous than those moving perpendicular to the field. In interstellar space, the direction of the moving charged particles is not expected to matter.
In the span of about 24 hours, the magnetic field originating from the sun also began piling up, like cars backed up on a freeway exit ramp. But scientists were able to quantify that the magnetic field barely changed direction — by no more than 2 degrees. ”
A day made such a difference in this region with the magnetic field suddenly doubling and becoming extraordinarily smooth,” said Leonard Burlaga, the lead author of one of the papers, and based at NASA’s Goddard Space Flight Center in Greenbelt, Md. “But since there was no significant change in the magnetic field direction, we’re still observing the field lines originating at the sun.”
NASA’s Jet Propulsion Laboratory, in Pasadena, Calif., built and operates the Voyager spacecraft. California Institute of Technology in Pasadena manages JPL for NASA. The Voyager missions are a part of NASA’s Heliophysics System Observatory, sponsored by the Heliophysics Division of the Science Mission Directorate at NASA Headquarters in Washington.
Voyager’s Ride on the Magnetic Highway (Courtesy of NASA/JPL)
For more information about the Voyager spacecraft mission, visit: http://www.nasa.gov/voyager and http://voyager.jpl.nasa.gov.
This article is a repost, credit: NASA, http://www.nasa.gov/mission_pages/voyager/voyager20130627.html.
This photo shows the ice front of Venable Ice Shelf, West Antarctica, in October 2008. It is an example of a small-size ice shelf that is a large melt water producer. The image was taken onboard the Chilean Navy P3 aircraft during the NASA/Centro de Estudios Cientificos, Chile campaign of Fall 2008 in Antarctica. Image credit: NASA/JPL-Caltech/UC Irvine
PASADENA, Calif. — Ocean waters melting the undersides of Antarctic ice shelves are responsible for most of the continent’s ice shelf mass loss, a new study by NASA and university researchers has found.
Scientists have studied the rates of basal melt, or the melting of the ice shelves from underneath, of individual ice shelves, the floating extensions of glaciers that empty into the sea. But this is the first comprehensive survey of all Antarctic ice shelves. The study found basal melt accounted for 55 percent of all Antarctic ice shelf mass loss from 2003 to 2008, an amount much higher than previously thought.
Antarctica holds about 60 percent of the planet’s fresh water locked into its massive ice sheet. Ice shelves buttress the glaciers behind them, modulating the speed at which these rivers of ice flow into the ocean. Determining how ice shelves melt will help scientists improve projections of how the Antarctic ice sheet will respond to a warming ocean and contribute to sea level rise. It also will improve global models of ocean circulation by providing a better estimate of the amount of fresh water ice shelf melting adds to Antarctic coastal waters.
The study uses reconstructions of ice accumulation, satellite and aircraft readings of ice thickness, and changes in elevation and ice velocity to determine how fast ice shelves melt and compare the mass lost with the amount released by the calving, or splitting, of icebergs.
Calving front of an ice shelf in West Antarctica. The traditional view on ice shelves, the floating extensions of seaward glaciers, has been that they mostly lose ice by shedding icebergs. A new study by NASA and university researchers has found that warm ocean waters melting the ice sheets from underneath account for 55 percent of all ice shelf mass loss in Antarctica. This image was taken during the 2012 Antarctic campaign of NASA’s Operation IceBridge, a mission that provided data for the new ice shelf study. Credit: NASA/GSFC/Jefferson Beck
“The traditional view on Antarctic mass loss is it is almost entirely controlled by iceberg calving,” said Eric Rignot of NASA’s Jet Propulsion Laboratory in Pasadena, Calif., and the University of California, Irvine. Rignot is lead author of the study to be published in the June 14 issue of the journal Science. “Our study shows melting from below by the ocean waters is larger, and this should change our perspective on the evolution of the ice sheet in a warming climate.”
Ice shelves grow through a combination of land ice flowing to the sea and snow accumulating on their surface. To determine how much ice and snowfall enters a specific ice shelf and how much makes it to an iceberg, where it may split off, the research team used a regional climate model for snow accumulation and combined the results with ice velocity data from satellites, ice shelf thickness measurements from NASA’s Operation IceBridge — an continuing aerial survey of Earth’s poles — and a new map of Antarctica’s bedrock.
Using this information, Rignot and colleagues were able to deduce whether the ice shelf was losing mass through basal melting or gaining it through the basal freezing of seawater.
In some places, basal melt exceeds iceberg calving. In other places, the opposite is true. But in total, Antarctic ice shelves lost 2,921 trillion pounds (1,325 trillion kilograms) of ice per year in 2003-2008 through basal melt, while iceberg formation accounted for 2,400 trillion pounds (1,089 trillion kilograms) of mass loss each year.
Basal melt can have a greater impact on ocean circulation than glacier calving. Icebergs slowly release melt water as they drift away from the continent. But strong melting near deep grounding lines, where glaciers lose their grip on the seafloor and start floating as ice shelves, discharges large quantities of fresher, lighter water near the Antarctic coast line. This lower-density water does not mix and sink as readily as colder, saltier water, and may be changing the rate of bottom water renewal.
“Changes in basal melting are helping to change the properties of Antarctic bottom water, which is one component of the ocean’s overturning circulation,” said author Stan Jacobs, an oceanographer at Columbia University’s Lamont-Doherty Earth Observatory in Palisades, N.Y. “In some areas it also impacts ecosystems by driving coastal upwelling, which brings up micronutrients like iron that fuel persistent plankton blooms in the summer.”
The study found basal melting is distributed unevenly around the continent. The three giant ice shelves of Ross, Filchner and Ronne, which make up two-thirds of the total Antarctic ice shelf area, accounted for only 15 percent of basal melting. Meanwhile, fewer than a dozen small ice shelves floating on “warm” waters (seawater only a few degrees above the freezing point) produced half of the total melt water during the same period. The scientists detected a similar high rate of basal melting under six small ice shelves along East Antarctica, a region not as well known because of a scarcity of measurements.
The researchers also compared the rates at which the ice shelves are shedding ice to the speed at which the continent itself is losing mass and found that, on average, ice shelves lost mass twice as fast as the Antarctic ice sheet did during the study period.
“Ice shelf melt doesn’t necessarily mean an ice shelf is decaying; it can be compensated by the ice flow from the continent,” Rignot said. “But in a number of places around Antarctica, ice shelves are melting too fast, and a consequence of that is glaciers and the entire continent are changing as well.”
This article is a repost, credit: NASA, http://www.nasa.gov/home/hqnews/2013/jun/HQ_13-183_Melting_Ice_Shelves.html.
The CARVE campaign flights are conducted aboard a specially instrumented NASA C-23 Sherpa aircraft from NASA’s Wallops Flight Facility, Wallops Island, Va. Most of the time, the CARVE scientists fly the plane “down in the mud,” at about 500 feet (152 meters) above the ground. The low altitude above the Arctic surface allows the scientists to measure interesting exchanges of carbon taking place between Earth’s surface and atmosphere. Image credit: NASA/JPL-Caltech
Flying low and slow above the wild, pristine terrain of Alaska’s North Slope in a specially instrumented NASA plane, research scientist Charles Miller of NASA’s Jet Propulsion Laboratory, Pasadena, Calif., surveys the endless whiteness of tundra and frozen permafrost below. On the horizon, a long, dark line appears. The plane draws nearer, and the mysterious object reveals itself to be a massive herd of migrating caribou, stretching for miles. It’s a sight Miller won’t soon forget.
“Seeing those caribou marching single-file across the tundra puts what we’re doing here in the Arctic into perspective,” said Miller, principal investigator of the Carbon in Arctic Reservoirs Vulnerability Experiment (CARVE), a five-year NASA-led field campaign studying how climate change is affecting the Arctic’s carbon cycle.
“The Arctic is critical to understanding global climate,” he said. “Climate change is already happening in the Arctic, faster than its ecosystems can adapt. Looking at the Arctic is like looking at the canary in the coal mine for the entire Earth system.”
Aboard the NASA C-23 Sherpa aircraft from NASA’s Wallops Flight Facility, Wallops Island, Va., Miller, CARVE Project Manager Steve Dinardo of JPL and the CARVE science team are probing deep into the frozen lands above the Arctic Circle. The team is measuring emissions of the greenhouse gases carbon dioxide and methane from thawing permafrost — signals that may hold a key to Earth’s climate future.
The CARVE scientists observed episodic, localized bursts of methane being emitted from the tundra as the spring thaw progressed northward over Alaska’s North Slope in May and June 2012. Reds and yellows represent the highest concentrations of methane, and blues the lowest. The methane is released from the topsoil as it thaws. Image credit: NASA/JPL-Caltech
What Lies Beneath
Permafrost (perennially frozen) soils underlie much of the Arctic. Each summer, the top layers of these soils thaw. The thawed layer varies in depth from about 4 inches (10 centimeters) in the coldest tundra regions to several yards, or meters, in the southern boreal forests. This active soil layer at the surface provides the precarious foothold on which Arctic vegetation survives. The Arctic’s extremely cold, wet conditions prevent dead plants and animals from decomposing, so each year another layer gets added to the reservoirs of organic carbon sequestered just beneath the topsoil.
Over hundreds of millennia, Arctic permafrost soils have accumulated vast stores of organic carbon – an estimated 1,400 to 1,850 petagrams of it (a petagram is 2.2 trillion pounds, or 1 billion metric tons). That’s about half of all the estimated organic carbon stored in Earth’s soils. In comparison, about 350 petagrams of carbon have been emitted from all fossil-fuel combustion and human activities since 1850. Most of this carbon is located in thaw-vulnerable topsoils within 10 feet (3 meters) of the surface.
But, as scientists are learning, permafrost – and its stored carbon – may not be as permanent as its name implies. And that has them concerned.
“Permafrost soils are warming even faster than Arctic air temperatures – as much as 2.7 to 4.5 degrees Fahrenheit (1.5 to 2.5 degrees Celsius) in just the past 30 years,” Miller said. “As heat from Earth’s surface penetrates into permafrost, it threatens to mobilize these organic carbon reservoirs and release them into the atmosphere as carbon dioxide and methane, upsetting the Arctic’s carbon balance and greatly exacerbating global warming.”
Current climate models do not adequately account for the impact of climate change on permafrost and how its degradation may affect regional and global climate. Scientists want to know how much permafrost carbon may be vulnerable to release as Earth’s climate warms, and how fast it may be released.
CARVing Out a Better Understanding of Arctic Carbon
Enter CARVE. Now in its third year, this NASA Earth Ventures program investigation is expanding our understanding of how the Arctic’s water and carbon cycles are linked to climate, as well as what effects fires and thawing permafrost are having on Arctic carbon emissions. CARVE is testing hypotheses that Arctic carbon reservoirs are vulnerable to climate warming, while delivering the first direct measurements and detailed regional maps of Arctic carbon dioxide and methane sources and demonstrating new remote sensing and modeling capabilities. About two dozen scientists from 12 institutions are participating.
“The Arctic is warming dramatically – two to three times faster than mid-latitude regions – yet we lack sustained observations and accurate climate models to know with confidence how the balance of carbon among living things will respond to climate change and related phenomena in the 21st century,” said Miller. “Changes in climate may trigger transformations that are simply not reversible within our lifetimes, potentially causing rapid changes in the Earth system that will require adaptations by people and ecosystems.”
The CARVE team flew test flights in 2011 and science flights in 2012. This April and May, they completed the first two of seven planned monthly campaigns in 2013, and they are currently flying their June campaign.
Each two-week flight campaign across the Alaskan Arctic is designed to capture seasonal variations in the Arctic carbon cycle: spring thaw in April/May, the peak of the summer growing season in June/July, and the annual fall refreeze and first snow in September/October. From a base in Fairbanks, Alaska, the C-23 flies up to eight hours a day to sites on Alaska’s North Slope, interior and Yukon River Valley over tundra, permafrost, boreal forests, peatlands and wetlands.
The C-23 won’t win any beauty contests – its pilots refer to it as “a UPS truck with a bad nose job.” Inside, it’s extremely noisy – the pilots and crew wear noise-cancelling headphones to communicate. “When you take the headphones off, it’s like being at a NASCAR race,” Miller quipped.
But what the C-23 lacks in beauty and quiet, it makes up for in reliability and its ability to fly “down in the mud,” so to speak. Most of the time, it flies about 500 feet (152 meters) above ground level, with periodic ascents to higher altitudes to collect background data. Most airborne missions measuring atmospheric carbon dioxide and methane do not fly as low. “CARVE shows you need to fly very close to the surface in the Arctic to capture the interesting exchanges of carbon taking place between Earth’s surface and atmosphere,” Miller said.
Onboard the plane, sophisticated instruments “sniff” the atmosphere for greenhouse gases. They include a very sensitive spectrometer that analyzes sunlight reflected from Earth’s surface to measure atmospheric carbon dioxide, methane and carbon monoxide. This instrument is an airborne simulator for NASA’s Orbiting Carbon Observatory-2 (OCO-2) mission to be launched in 2014. Other instruments analyze air samples from outside the plane for the same chemicals. Aircraft navigation data and basic weather data are also collected. Initial data are delivered to scientists within 12 hours. Air samples are shipped to the University of Colorado’s Institute for Arctic and Alpine Research Stable Isotope Laboratory and Radiocarbon Laboratory in Boulder for analyses to determine the carbon’s sources and whether it came from thawing permafrost.
Much of CARVE’s science will come from flying at least three years, Miller says. “We are showing the power of using dependable, low-cost prop planes to make frequent, repeat measurements over time to look for changes from month to month and year to year.”
Ground observations complement the aircraft data and are used to calibrate and validate them. The ground sites serve as anchor points for CARVE’s flight tracks. Ground data include air samples from tall towers and measurements of soil moisture and temperature to determine whether soil is frozen, thawed or flooded.
A Tale of Two Greenhouse Gases
It’s important to accurately characterize the soils and state of the land surfaces. There’s a strong correlation between soil characteristics and release of carbon dioxide and methane. Historically, the cold, wet soils of Arctic ecosystems have stored more carbon than they have released. If climate change causes the Arctic to get warmer and drier, scientists expect most of the carbon to be released as carbon dioxide. If it gets warmer and wetter, most will be in the form of methane.
The distinction is critical. Molecule per molecule, methane is 22 times more potent as a greenhouse gas than carbon dioxide on a 100-year timescale, and 105 times more potent on a 20-year timescale. If just one percent of the permafrost carbon released over a short time period is methane, it will have the same greenhouse impact as the 99 percent that is released as carbon dioxide. Characterizing this methane to carbon dioxide ratio is a major CARVE objective.
There are other correlations between Arctic soil characteristics and the release of carbon dioxide and methane. Variations in the timing of spring thaw and the length of the growing season have a major impact on vegetation productivity and whether high northern latitude regions generate or store carbon.
CARVE is also studying wildfire impacts on the Arctic’s carbon cycle. Fires in boreal forests or tundra accelerate the thawing of permafrost and carbon release. Detailed fire observation records since 1942 show the average annual number of Alaska wildfires has increased, and fires with burn areas larger than 100,000 acres are occurring more frequently, trends scientists expect to accelerate in a warming Arctic. CARVE’s simultaneous measurements of greenhouse gases will help quantify how much carbon is released to the atmosphere from fires in Alaska – a crucial and uncertain element of its carbon budget.
Early Results
The CARVE science team is busy analyzing data from its first full year of science flights. What they’re finding, Miller said, is both amazing and potentially troubling.
“Some of the methane and carbon dioxide concentrations we’ve measured have been large, and we’re seeing very different patterns from what models suggest,” Miller said. “We saw large, regional-scale episodic bursts of higher-than-normal carbon dioxide and methane in interior Alaska and across the North Slope during the spring thaw, and they lasted until after the fall refreeze. To cite another example, in July 2012 we saw methane levels over swamps in the Innoko Wilderness that were 650 parts per billion higher than normal background levels. That’s similar to what you might find in a large city.”
Ultimately, the scientists hope their observations will indicate whether an irreversible permafrost tipping point may be near at hand. While scientists don’t yet believe the Arctic has reached that tipping point, no one knows for sure. “We hope CARVE may be able to find that ‘smoking gun,’ if one exists,” Miller said.
Other institutions participating in CARVE include City College of New York; the joint University of Colorado/National Oceanic and Atmospheric Administration’s Cooperative Institute for Research in Environmental Sciences, Boulder, Colo.; San Diego State University; University of California, Irvine; California Institute of Technology, Pasadena; Harvard University, Cambridge, Mass.; University of California, Berkeley; Lawrence Berkeley National Laboratory, Berkeley, Calif.; University of California, Santa Barbara; NOAA’s Earth System Research Laboratory, Boulder, Colo.; and University of Melbourne, Victoria, Australia.
For more information on CARVE, visit: http://science.nasa.gov/missions/carve/ .
This article is a repost, credit: NASA, http://www.nasa.gov/topics/earth/features/earth20130610.html.
WASHINGTON — Measurements taken by NASA’s Mars Science Laboratory (MSL) mission as it delivered the Curiosity rover to Mars in 2012 are providing NASA the information it needs to design systems to protect human explorers from radiation exposure on deep-space expeditions in the future.
MSL’s Radiation Assessment Detector (RAD) is the first instrument to measure the radiation environment during a Mars cruise mission from inside a spacecraft that is similar to potential human exploration spacecraft. The findings will reduce uncertainty about the effectiveness of radiation shielding and provide vital information to space mission designers who will need to build in protection for spacecraft occupants in the future.
“As this nation strives to reach an asteroid and Mars in our lifetimes, we’re working to solve every puzzle nature poses to keep astronauts safe so they can explore the unknown and return home,” said William Gerstenmaier, NASA’s associate administrator for human exploration and operations in Washington. “We learn more about the human body’s ability to adapt to space every day aboard the International Space Station. As we build the Orion spacecraft and Space Launch System rocket to carry and shelter us in deep space, we’ll continue to make the advances we need in life sciences to reduce risks for our explorers. Curiosity’s RAD instrument is giving us critical data we need so that we humans, like the rover, can dare mighty things to reach the Red Planet.”
The findings, which are published in the May 31 edition of the journal Science, indicate radiation exposure for human explorers could exceed NASA’s career limit for astronauts if current propulsion systems are used.
Two forms of radiation pose potential health risks to astronauts in deep space. One is galactic cosmic rays (GCRs), particles caused by supernova explosions and other high-energy events outside the solar system. The other is solar energetic particles (SEPs) associated with solar flares and coronal mass ejections from the sun.
Radiation exposure is measured in units of Sievert (Sv) or milliSievert (one one-thousandth Sv). Long-term population studies have shown exposure to radiation increases a person’s lifetime cancer risk. Exposure to a dose of 1 Sv, accumulated over time, is associated with a 5 percent increase in risk for developing fatal cancer.
NASA has established a 3 percent increased risk of fatal cancer as an acceptable career limit for its astronauts currently operating in low-Earth orbit. The RAD data showed the Curiosity rover was exposed to an average of 1.8 milliSieverts of GCR per day on its journey to Mars. Only about 5 percent of the radiation dose was associated with solar particles because of a relatively quiet solar cycle and the shielding provided by the spacecraft.
The RAD data will help inform current discussions in the United States medical community, which is working to establish exposure limits for deep-space explorers in the future.
“In terms of accumulated dose, it’s like getting a whole-body CT scan once every five or six days,” said Cary Zeitlin, a principal scientist at the Southwest Research Institute (SwRI) in San Antonio and lead author of the paper on the findings. “Understanding the radiation environment inside a spacecraft carrying humans to Mars or other deep space destinations is critical for planning future crewed missions.”
Current spacecraft shield much more effectively against SEPs than GCRs. To protect against the comparatively low energy of typical SEPs, astronauts might need to move into havens with extra shielding on a spacecraft or on the Martian surface, or employ other countermeasures. GCRs tend to be highly energetic, highly penetrating particles that are not stopped by the modest shielding provided by a typical spacecraft.
“Scientists need to validate theories and models with actual measurements, which RAD is now providing,” said Donald M. Hassler, a program director at SwRI and principal investigator of the RAD investigation. “These measurements will be used to better understand how radiation travels through deep space and how it is affected and changed by the spacecraft structure itself. The spacecraft protects somewhat against lower energy particles, but others can propagate through the structure unchanged or break down into secondary particles.”
After Curiosity landed on Mars in August, the RAD instrument continued operating, measuring the radiation environment on the planet’s surface. RAD data collected during Curiosity’s science mission will continue to inform plans to protect astronauts as NASA designs future missions to Mars in the coming decades.
SwRI, together with Christian Albrechts University in Kiel, Germany, built RAD with funding from NASA’s Human Exploration and Operations Mission Directorate and Germany’s national aerospace research center, Deutsches Zentrum fur Luft- und Raumfahrt.
NASA’s Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, Calif., manages the Mars Science Laboratory Project. The NASA Science Mission Directorate at NASA Headquarters in Washington manages the Mars Exploration Program.
For more information about the findings and the Mars Science Laboratory mission, visit: http://www.nasa.gov/msl
For more information about NASA human spaceflight and exploration, visit: http://www.nasa.gov/exploration
This article is a repost, credit: NASA, http://www.nasa.gov/home/hqnews/2013/may/HQ_13-165_MSL_Radiation_Findings.html.
Updated Curiosity Self-Portrait at ‘John Klein’ This self-portrait of NASA’s Mars rover Curiosity combines dozens of exposures taken by the rover’s Mars Hand Lens Imager (MAHLI) during the 177th Martian day, or sol, of Curiosity’s work on Mars (Feb. 3, 2013), plus three exposures taken during Sol 270 (May 10, 2013) to update the appearance of part of the ground beside the rover. The updated area, which is in the lower left quadrant of the image, shows gray-powder and two holes where Curiosity used its drill on the rock target “John Klein.” The portion has been spliced into a self-portrait that was prepared and released in February (http://photojournal.jpl.nasa.gov/catalog/PIA16764), before the use of the drill. The result shows what the site where the self-portrait was taken looked like by the time the rover was ready to drive away from that site in May 2013. The rover’s robotic arm is not visible in the mosaic. MAHLI, which took the component images for this mosaic, is mounted on a turret at the end of the arm. Wrist motions and turret rotations on the arm allowed MAHLI to acquire the mosaic’s component images. The arm was positioned out of the shot in the images, or portions of images, used in the mosaic. Malin Space Science Systems, San Diego, developed, built and operates MAHLI. NASA’s Jet Propulsion Laboratory, Pasadena, Calif., manages the Mars Science Laboratory Project and the mission’s Curiosity rover for NASA’s Science Mission Directorate in Washington. The rover was designed and assembled at JPL, a division of the California Institute of Technology in Pasadena. Image credit: NASA/JPL-Caltech/MSSS Courtesy of NASA
WASHINGTON — NASA will host a media teleconference at 2:30 p.m. EDT Thursday, May 30, to present new findings from the Mars Science Laboratory Radiation Assessment Detector (RAD) aboard the rover Curiosity.
The journal Science has embargoed details until 2 p.m. May 30.
The briefing participants are:
Donald M. Hassler, RAD principal investigator and program director, Southwest Research Institute (SwRI), San Antonio
Cary Zeitlin, principal scientist, SwRI
Eddie Semones, spaceflight radiation health officer, NASA’s Johnson Space Center, Houston
Chris Moore, deputy director of advanced exploration systems, NASA Headquarters, Washington
For dial-in information, media representatives should e-mail their name, affiliation and telephone number to Trent Perrotto at [email protected] by noon May 30.
SwRI and Christian Albrechts University in Kiel, Germany, built RAD with funding from NASA’s Human Exploration and Operations Mission Directorate and Germany’s national aerospace research center, Deutsches Zentrum für Luft- und Raumfahrt. NASA’s Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, Calif., manages the Mars Science Laboratory Project. NASA’s Science Mission Directorate in Washington manages the Mars Exploration Program.
Visuals will be posted at the start of the teleconference on NASA’s Mars Science Laboratory website at: http://go.nasa.gov/curiositytelecon.
Audio of the teleconference will be streamed live on NASA’s website at: http://www.nasa.gov/newsaudio.
This article is a repost, credit: NASA, http://www.nasa.gov/home/hqnews/2013/may/HQ_M13-085_Curiosity_RAD_Findings.html.
