Electromagnetic waves linked to particle fallout in Earth's atmosphere, new study finds

In a new study that sheds light on space weather's impact on Earth, Dartmouth researchers and their colleagues show for the first time that plasma waves buffeting the planet's radiation belts are responsible for scattering charged particles into the atmosphere.

The study is the most detailed analysis so far of the link between these waves and the fallout of electrons from the planet's radiation belts. The belts are impacted by fluctuations in "space weather" caused by solar activity that can disrupt GPS satellites, communication systems, power grids and manned space exploration.

The results appear in the journal Geophysical Research Letters. A PDF is available on request.

The Dartmouth space physicists are part of a NASA-sponsored team that studies the Van Allen radiation belts, which are donut-shaped belts of charged particles held in place by Earth's magnetosphere, the magnetic field surrounding our planet. In a quest to better predict space weather, the Dartmouth researchers study the radiation belts from above and below in complementary approaches -- through satellites (the twin NASA Van Allen Probes) high over Earth and through dozens of instrument-laden balloons (BARREL, or Balloon Array for Radiation belt Relativistic Electron Losses) at lower altitudes to assess the particles that rain down.

The Van Allen Probes measure particle, electric and magnetic fields, or basically everything in the radiation belt environment, including the electrons, which descend following Earth's magnetic field lines that converge at the poles. This is why the balloons are launched from Antarctica, where some of the best observations can be made. As the falling electrons collide with the atmosphere, they produce X-rays and that is what the balloon instruments are actually recording.

"We are measuring those atmospheric losses and trying to understand how the particles are getting kicked into the atmosphere," says co-author Robyn Millan, an associate professor in Dartmouth's Department of Physics and Astronomy and the principal investigator of BARREL. "Our main focus has been really on the processes that are occurring out in space. Particles in the Van Allen belts never reach the ground, so they don't constitute a health threat. Even the X-rays get absorbed, which is why we have to go to balloon altitudes to see them."

In their new study, the BARREL researchers' major objective was to obtain simultaneous measurements of the scattered particles and of ionoized gas called plasma out in space near Earth's equator. They were particularly interested in simultaneous measurements of a particular kind of plasma wave called electromagnetic ion cyclotron waves and whether these waves were responsible for scattering the particles, which has been an open question for years.

The researchers obtained measurements in Antarctica in 2013 when the balloons and both the Geostationary Operational Environmental Satellite (GOES) and Van Allen Probe satellites were near the same magnetic field line. They put the satellite data into their model that tests the wave-particle interaction theory, and the results suggest the wave scattering was the cause of the particle fallout. "This is the first real quantitative test of the theory," Millan says.

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NASA satellite set to get the dirt on Earth's soil moisture

A new NASA satellite that will peer into the topmost layer of Earth's soils to measure the hidden waters that influence our weather and climate is in final preparations for a Jan. 29 dawn launch from California.

The Soil Moisture Active Passive (SMAP) mission will take the pulse of a key measure of our water planet: how freshwater cycles over Earth's land surfaces in the form of soil moisture. The mission will produce the most accurate, highest-resolution global maps ever obtained from space of the moisture present in the top 2 inches (5 centimeters) of Earth's soils. It also will detect and map whether the ground is frozen or thawed. This data will be used to enhance scientists' understanding of the processes that link Earth's water, energy and carbon cycles.

"With data from SMAP, scientists and decision makers around the world will be better equipped to understand how Earth works as a system and how soil moisture impacts a myriad of human activities, from floods and drought to weather and crop yield forecasts," said Christine Bonniksen, SMAP program executive with the Science Mission Directorate's Earth Science Division at NASA Headquarters in Washington. "SMAP's global soil moisture measurements will provide a new capability to improve our understanding of Earth's climate."

Globally, the volume of soil moisture varies between three and five percent in desert and arid regions, to between 40 and 50 percent in saturated soils. In general, the amount depends on such factors as precipitation patterns, topography, vegetation cover and soil composition. There are not enough sensors in the ground to map the variability in global soil moisture at the level of detail needed by scientists and decision makers. From space, SMAP will produce global maps with 6-mile (10-kilometer) resolution every two to three days.

Researchers want to measure soil moisture and its freeze/thaw state better for numerous reasons. Plants and crops draw water from the soil through their roots to grow. If soil moisture is inadequate, plants fail to grow, which over time can lead to reduced crop yields. Also, energy from the sun evaporates moisture in the soil, thereby cooling surface temperatures and also increasing moisture in the atmosphere, allowing clouds and precipitation to form more readily. In this way, soil moisture has a significant effect on both short-term regional weather and longer-term global climate.

In summer, plants in Earth's northern boreal regions -- the forests found in Earth's high northern latitudes -- take in carbon dioxide from the air and use it to grow, but lay dormant during the winter freeze period. All other factors being equal, the longer the growing season, the more carbon plants take in and the more effective forests are in removing carbon dioxide from the air. Since the start of the growing season is marked by the thawing and refreezing of water in soils, mapping the freeze/thaw state of soils with SMAP will help scientists more accurately account for how much carbon plants are removing from the atmosphere each year. This information will lead to better estimates of the carbon budget in the atmosphere and, hence, better assessments of future global warming.

SMAP data will enhance our confidence in projections of how Earth's water cycle will respond to climate change.

"Assessing future changes in regional water availability is perhaps one of the greatest environmental challenges facing the world today," said Dara Entekhabi, SMAP science team leader at the Massachusetts Institute of Technology in Cambridge. "Today's computer models disagree on how the water cycle -- precipitation, clouds, evaporation, runoff, soil water availability -- will increase or decrease over time and in different regions as our world warms. SMAP's higher-resolution soil moisture data will improve the models used to make daily weather and longer-term climate predictions."

SMAP also will advance our ability to monitor droughts, predict floods and mitigate the related impacts of these extreme events. It will allow the monitoring of regional deficits in soil moisture and provide critical inputs into drought monitoring and early warning systems used by resource managers. The mission's high-resolution observations of soil moisture will improve flood warnings by providing information on ground saturation conditions before rainstorms.

SMAP's two advanced instruments work together to produce soil moisture maps. Its active radar works much like a flash camera, but instead of transmitting visible light, it transmits microwave pulses that pass through clouds and moderate vegetation cover to the ground and measures how much of that signal is reflected back. Its passive radiometer operates like a natural-light camera, capturing emitted microwave radiation without transmitting a pulse. Unlike traditional cameras, however, SMAP's images are in the microwave range of the electromagnetic spectrum, which is invisible to the naked eye. Microwave radiation is sensitive to how much moisture is contained in the soil.

The two instruments share a large, lightweight reflector antenna that will be unfurled in orbit like a blooming flower and then spin at about 14 revolutions per minute. The antenna will allow the instruments to collect data across a 621-mile (1,000-kilometer) swath, enabling global coverage every two to three days.

SMAP's radiometer measurements extend and expand on soil moisture measurements currently made by the European Space Agency's Soil Moisture Ocean Salinity (SMOS) mission, launched in 2009. With the addition of a radar instrument, SMAP's soil moisture measurements will be able to distinguish finer features on the ground.

SMAP will launch from Vandenberg Air Force Base on a United Launch Alliance Delta II rocket and maneuver into a 426-mile (685-kilometer) altitude, near-polar orbit that repeats exactly every eight days. The mission is designed to operate at least three years.

SMAP is managed for NASA's Science Mission Directorate in Washington by the agency's Jet Propulsion Laboratory in Pasadena, California, with instrument hardware and science contributions made by NASA's Goddard Space Flight Center in Greenbelt, Maryland. JPL is responsible for project management, system engineering, radar instrumentation, mission operations and the ground data system. Goddard is responsible for the radiometer instrument. Both centers collaborate on science data processing and delivery to the Alaska Satellite Facility, in Fairbanks, and the National Snow and Ice Data Center, at the University of Colorado in Boulder, for public distribution and archiving. NASA's Launch Services Program at the agency's Kennedy Space Center in Florida is responsible for launch management. JPL is managed for NASA by the California Institute of Technology in Pasadena.

For more information about the Soil Moisture Active Passive mission, visit:

http://www.nasa.gov/smap

and

http://smap.jpl.nasa.gov

SMAP will be the fifth NASA Earth science mission to launch within a 12-month period. NASA monitors Earth's vital signs from land, air and space with a fleet of satellites and ambitious airborne and ground-based observation campaigns. NASA develops new ways to observe and study Earth's interconnected natural systems with long-term data records and computer analysis tools to better see how our planet is changing.

For more information about NASA's Earth science activities, visit:

http://www.nasa.gov/earthrightnow

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Temperature anomalies are warming faster than Earth's average, study finds

It's widely known that Earth's average temperature has been rising. But research by an Indiana University geographer and colleagues finds that spatial patterns of extreme temperature anomalies -- readings well above or below the mean -- are warming even faster than the overall average.

And trends in extreme heat and cold are important, said Scott M. Robeson, professor of geography in the College of Arts and Sciences at IU Bloomington. They have an outsized impact on water supplies, agricultural productivity and other factors related to human health and well-being.

"Average temperatures don't tell us everything we need to know about climate change," he said. "Arguably, these cold extremes and warm extremes are the most important factors for human society."

Robeson is the lead author of the article "Trends in hemispheric warm and cold anomalies," which will be published in the journal Geophysical Research Letters and is available online. Co-authors are Cort J. Willmott of the University of Delaware and Phil D. Jones of the University of East Anglia.

The researchers analyzed temperature records for the years 1881 to 2013 from HadCRUT4, a widely used data set for land and sea locations compiled by the University of East Anglia and the U.K. Met Office. Using monthly average temperatures at points across the globe, they sorted them into "spatial percentiles," which represent how unusual they are by their geographic size.

Their findings include:

Temperatures at the cold and warm "tails" of the spatial distribution -- the 5th and 95th percentiles -- increased more than the overall average Earth temperature.Over the 130-year record, cold anomalies increased more than warm anomalies, resulting in an overall narrowing of the range of Earth's temperatures.In the past 30 years, however, that pattern reversed, with warm anomalies increasing at a faster rate than cold anomalies. "Earth's temperature was becoming more homogenous with time," Robeson said, "but now it's not."

The study records separate results for the Northern and Southern Hemispheres. Temperatures are considerably more volatile in the Northern Hemisphere, an expected result because there's considerably less land mass in the South to add complexity to weather systems.

The study also examined anomalies during the "pause" in global warming that scientists have observed since 1998. While a 16-year-period is too short a time to draw conclusions about trends, the researchers found that warming continued at most locations on the planet and during much of the year, but that warming was offset by strong cooling during winter months in the Northern Hemisphere.

"There really hasn't been a pause in global warming," Robeson said. "There's been a pause in Northern Hemisphere winter warming."

Co-author Jones of the University of East Anglia said the study provides scientists with better knowledge about what's taking place with Earth's climate. "Improved understanding of the spatial patterns of change over the three periods studied are vital for understanding the causes of recent events," he said.

It may seem counterintuitive that global warming would be accompanied by colder winter weather at some locales. But Robeson said the observation aligns with theories about climate change, which hold that amplified warming in the Arctic region produces changes in the jet stream, which can result in extended periods of cold weather at some locations in the mid-northern latitudes.

And while the rate of planetary warming has slowed in the past 16 years, it hasn't stopped. The World Meteorological Organization announced this month that 2014 is on track to be one of the warmest, if not the warmest, years on record as measured by global average temperatures.

In the U.S., the East has been unusually cold and snowy in recent years, but much of the West has been unusually warm and has experienced drought. And what happens here doesn't necessarily reflect conditions on the rest of the planet. Robeson points out that the United States, including Alaska, makes up only 2 percent of Earth's surface.

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Climatologists offer reason behind widening of Earth's tropical belt

A awesome-water anomaly referred to as La Ni?a occupied tropical Gulf Of Mexico throughout 2007 and early 2008. In April 2008, researchers at NASA’s Jet Space Laboratory introduced that although the La Ni?a was weakening, the Off-shore Decadal Oscillation (PDO) -- a bigger-scale, reduced-cycling sea pattern—had moved to the awesome phase. This picture shows the ocean surface temperature anomaly within the Gulf Of Mexico from April 14–21, 2008. Places in which the Off-shore was cooler than usual are blue, places where temps were average are whitened, and places in which the sea was warmer than usual are red-colored. The broad section of cooler-than-average water from the coast of The United States from Alaska (top center) towards the equator is really a classic feature from the awesome phase from the PDO. The awesome waters wrap inside a horseshoe shape around a core of warmer-than-average water. (Within the warm phase, the pattern is corrected). Unlike El Ni?o and La Ni?a, which might occur every 3 to many years and last from 6 to 18 several weeks, the PDO usually stays within the same phase for twenty to thirty years. The change within the PDO might have significant implications for global climate.Credit: NASA image by Jesse Allen, AMSR-E data processed and supplied by Chelle Gentemann and Frank Wentz, Remote Realizing Systems Recent reports have proven that Earth's tropical belt -- demarcated, roughly, through the Tropics of Cancer and Capricorn -- has progressively broadened since a minimum of the late seventies. Several explanations with this widening happen to be suggested, for example radiative forcing because of green house gas increase and stratospheric ozone depletion.

Now, a group of climatologists, brought by scientists in the College of California, Riverside, posits the recent widening from the tropical belt is mainly triggered by multi-decadal ocean surface temperature variability within the Gulf Of Mexico. This variability includes the Off-shore Decadal Oscillation (PDO), a lengthy-resided El Ni?o-like pattern of Off-shore climate variability that actually works just like a switch every 3 decades approximately between two different circulation designs within the North Gulf Of Mexico. Additionally, it includes, the scientists say, anthropogenic contaminants, which act to change the PDO.

Study results appear March 16 in Character Geoscience.

"Prior analyses have discovered that climate models underestimate the observed rate of tropical widening, resulting in questions about possible model inadequacies, possible errors within the findings, and insufficient confidence later on forecasts," stated Robert J. Allen, a helper professor of climatology in UC Riverside's Department of Earth Sciences, who brought the research. "In addition, there's been no obvious reason behind what's driving the widening."

Now Allen's team finds the recent tropical widening is basically driven through the PDO.

"Even though this widening is recognized as a 'natural' mode of climate variability, implying tropical widening is mainly driven by internal dynamics from the climate system, we reveal that anthropogenic contaminants have driven trends within the PDO," Allen stated. "Thus, tropical widening relates to both PDO and anthropogenic contaminants."

Widening concerns

Tropical widening is connected with several significant alterations in our climate, including changes in large-scale atmospheric circulation, like storm tracks, and major climate zones. For instance, in Los Angeles, tropical widening might be connected with less precipitation.

Of particular concern would be the semi-arid regions poleward from the subtropical dry devices, such as the Mediterranean, the north western U . s . States and northern Mexico, southern Australia, southern Africa, and areas of South Usa. A poleward growth of the tropics will probably bring even drier conditions to those heavily populated regions, but might bring elevated moisture with other areas.

Widening from the tropics would also most likely be connected with poleward movement of major extratropical climate zones because of changes able of jet streams, storm tracks, mean position of everywhere pressure systems, and connected precipitation routines. A rise in the width from the tropics could boost the area impacted by tropical storms (severe weather), or could change climatological tropical cyclone development regions and tracks.

Belt contraction

Allen's research team also demonstrated that just before the current (since ~1980 let's start) tropical widening, tropical belt really contracted for many decades, in conjuction with the turnaround of the PDO throughout this earlier period of time.

"The turnaround of the PDO, consequently, might be associated with the worldwide rise in anthropogenic pollutant pollutants just before the ~ early eighties," Allen stated.

Analysis

Allen's team examined IPCC AR5 (fifth Assessment Report) climate models, several observational and reanalysis data sets, and carried out their very own climate model experiments to evaluate tropical widening, and also to isolate the primary cause.

"Whenever we examined IPCC climate model experiments driven using the time-evolution of observed ocean surface temps, we found much bigger rates of tropical widening, in better agreement towards the observed rate--especially in the Northern Hemisphere," Allen stated. "This immediately pointed to the significance of ocean surface temps, as well as recommended that models can handle recreating the observed rate of tropical widening, that's, they weren't 'deficient' in some manner.Inch

Urged by their findings, the scientists then requested the issue, "What part of the SSTs is driving the development?Inch They found the solution within the leading pattern of ocean surface temperature variability within the North Off-shore: the PDO.

They supported their argument by re-examining the models with PDO-variability statistically removed.

"Within this situation, we found tropical widening -- especially in the Northern Hemisphere -- is totally removed," Allen stated. "This is correct for kinds of models--individuals driven with observed ocean surface temps, and also the combined climate appliances simulate evolution of both atmosphere and sea and therefore are thus unlikely to yield the actual-world evolution from the PDO.

"When we stratify the speed of tropical widening within the combined models by their particular PDO evolution," Allen added, "we discover a statistically significant relationship: combined appliances simulate a bigger PDO trend have bigger tropical widening, and the other way around. Thus, even combined models can simulate the observed rate of tropical widening, but only when they simulate the actual-world evolution from the PDO."

Future work

Next, the scientists is going to be searching at just how anthropogenic contaminants, by modifying the PDO and massive weather systems, have affected precipitation within the Southwest U . s . States, including Los Angeles.

"Future pollutants paths show decreased pollutant pollutants with the twenty-first century, implying contaminants will continue to drive an optimistic PDO and tropical widening," Allen stated.

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Satellite trio to explore the Earth's magnetic field

In a dense fog, a Russian Rockot rocket on 22 November 2013 cleared the launchpad of the Baikonur Cosmodrome on schedule at 13:02:15 CET. In the tip of the rocket: three identical satellites to measure the Earth's magnetic field. A good hour and a half later, at 14:37:48 CET, the report of success: all three satellites separated seamlessly from the carrier rocket and the ground stations Kiruna (Sweden) and Longyearbyen /Svalbard (Norway) were able to establish radio contact with them. GFZ scientists and invited guests observed the start of the mission called SWARM of the European Space Agency in Darmstadt via remote transmission.

Professor Johanna Wanka, Federal Minister of Education and Research said on the occasion of the perfect start of the mission: "We are very pleased that this European mission has started so smoothly.The magnetic field of the Earth is our shield against cosmic particle radiation. But it is subject to natural fluctuations, from the Earth's interior or eruptions on the Sun. Improving the exploration of its function and recording space weather data more accurately allows us to draw conclusions for life on our planet."

Professor Reinhard Huettl, Chairman of the Board of the GFZ German Research Centre for Geosciences pointed out a Potsdam success story: "The three satellites are direct developments from the CHAMP mission of the GFZ, which was launched in 2000. CHAMP with his followers GRACE and SWARM proves to be the founding father of a whole generation of satellites and space-based measurement methods."

A trio for the magnetic field

SWARM is an ESA mission as part of its "Living Planet" program. "The satellite swarm -- hence the name -- is to measure the Earth's magnetic field from space with unprecedented precision for at least four years," elaborated Professor Huettl. For this, the three satellites fly in an optimized formation: two satellites (SWARM-A, SWARM-B) fly in an altitude of 450 kilometers with a distance of 150 kilometers alongside one another, the third (SWARM-C) ascends into a higher orbit at 530 km altitude. The reason for this complex formation flight lies in the magnetic field itself: it is generated by the flow of electrically conducting liquid iron in the outer core oft he Earth, 2900 kilometers beneath our feet. It is influenced by the conductivity and the dynamics of the overlying mantle (up to 40 kilometers below the Earth's surface). Finally, the magnetized rocks of the Earth's crust contribute to the Earth's magnetic field. In addition, the sun and currents in near-Earth space influence the Earth's magnetic field from the outside. In order to study these individual components, the total signal of the magnetic field measured by the satellite needs to be separated into its individual components. "From its distance of 150 kilometers, the lower flying SWARM pair can look at the magnetic field of the Earth's crust with a stereo view," explains Professor Hermann L?hr , one of the three Principle Investigators of the mission, member of the SWARM Mission Advisory Group and Head of the German SWARM Project Office at the GFZ. "We can therefore analyze this component with very high accuracy." The third, upper SWARM satellite can in turn precisely determine the force of the magnetic field as it decreases with increasing altitude. Also, over time this satellite flies in a progressively increasing angle to the path of the lower pair. The total measurement will give a picture of the earth's magnetic field with a precision never achieved before.

Almost as a side effect, the possibility arises to observe space weather more accurately. What is understood by this are flares of our sun, but also magnetic storms generated by distant stars that can interfere with or even paralyze our technical civilization. For example, a strong solar storm in 1989 caused a breakdown of the electricity supply in Canada.

About the satellites

The three SWARM satellites together cost about 220 million euros, each weighs 500 kg. Inside the carrier rocket, a four-meter long measuring arm is folded on the back of the five meter long satellite body. This boom is folded out several hours after the deployment of the satellite, once the on-board operating system has been initiated. The reason for this is that the surface of the satellite is equipped with solar cells for the power supply. The magnetic field generated by the current, however, would interfere with the measurement, therefore, the magnetic field measuring instruments are mounted on the measuring arm.

At the tip of the boom, the particularly sensitive apparatus for measuring the magnetic field strength is installed, the sensors for determining the direction of the magnetic field are in its center. In the same position, three star sensors allow the satellite to determine and corrected its location.

To begin with, the three satellites fly parallel on a north-south path at about 88? inclination. Swarm-C is then slowly deflected by 30? per year and thus continues to fly at an increasing angle to the orbit of Swarm-A and -B.

Cite This Page:

Helmholtz Centre Potsdam - GFZ German Research Centre for Geosciences. "Satellite trio to explore the Earth's magnetic field." ScienceDaily. ScienceDaily, 22 November 2013. .Helmholtz Centre Potsdam - GFZ German Research Centre for Geosciences. (2013, November 22). Satellite trio to explore the Earth's magnetic field. ScienceDaily. Retrieved February 1, 2014 from www.sciencedaily.com/releases/2013/11/131122103703.htmHelmholtz Centre Potsdam - GFZ German Research Centre for Geosciences. "Satellite trio to explore the Earth's magnetic field." ScienceDaily. www.sciencedaily.com/releases/2013/11/131122103703.htm (accessed February 1, 2014).

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Watching Earth's winds, on a shoestring

Built with spare parts and without a moment to spare, the International Space Station (ISS)-RapidScat isn't your average NASA Earth science mission.

Short for Rapid Scatterometer, ISS-RapidScat will monitor ocean winds from the vantage point of the space station . It will join a handful of other satellite scatterometer missions that make essential measurements used to support weather and marine forecasting, including the tracking of storms and hurricanes. It will also help improve our understanding of how interactions between Earth's ocean and atmosphere influence our climate.

Scientists study ocean winds for a variety of reasons. Winds over the ocean are an important part of weather systems, and in severe storms such as hurricanes they can inflict major damage. Ocean storms drive coastal surges, which are a significant hazard for populations. At the same time, by driving warm surface ocean water away from the coast, ocean winds cause nutrient-rich deep water to well up, providing a major source of food for coastal fisheries. Changes in ocean wind also help us monitor large-scale changes in Earth's climate, such as El Ni?o .

Scatterometers work by safely bouncing low-energy microwaves -- the same kind used at high energy to warm up food in your kitchen -- off the surface of Earth. In this case, the surface is not land, but the ocean. By measuring the strength and direction of the microwave echo, ISS-RapidScat will be able to determine how fast, and in what direction, ocean winds are blowing.

"Microwave energy emitted by a radar instrument is reflected back to the radar more strongly when the surface it illuminates is rougher," explains Ernesto Rodr?guez, principal investigator for ISS-RapidScat at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "When wind blows over water, it causes waves to develop along the direction of wind. The stronger the wind, the larger the waves."

ISS-RapidScat continues a legacy of measuring ocean winds from space that began in 1978 with the launch of NASA's SeaSat satellite. Most recently, NASA's QuikScat scatterometer, which launched in 1999, gave us a dynamic picture of the world's ocean winds.

But when QuikScat lost its ability to produce ocean wind measurements in 2009, science suffered from the loss of the data. In the summer of 2012, an opportunity arose to fly a scatterometer instrument on the space station. ISS-RapidScat was the result .

Most scatterometer-carrying satellites fly in what's called a sun-synchronous orbit around Earth. In other words, they cross Earth's equator at the same local time every orbit. The space station, however, will carry the ISS-RapidScat in a non-sun-synchronous orbit. This means the instrument will see different parts of the planet at different times of day, making measurements in the same spot within less than an hour before or after another instrument makes its own observations. These all-hour measurements will allow ISS-RapidScat to pick up the effects of the sun on ocean winds as the day progresses. In addition, the space station's coverage over the tropics means that ISS-RapidScat will offer extra tracking of storms that may develop into hurricanes or other tropical cyclones.

Anywhere the wind blows

"We'll be able to see how wind speed changes with the time of day," said Rodr?guez. "ISS-RapidScat will link together all previous and current scatterometer missions, providing us with a more complete picture of how ocean winds change. Combined with data from the European ASCAT scatterometer mission, we'll be able to observe 90 percent of Earth's surface at least once a day, and in many places, several times a day."

ISS-RapidScat's near-global coverage of Earth's ocean -- within the space station's orbit inclination of 51.6 degrees north and south of the equator -- will make it an important tool for scientists who observe and predict Earth's weather. "Frequent observations of the winds over the ocean are used by meteorologists to improve weather and hurricane forecasts and by the operational weather communities to improve numerical weather models," said Rodr?guez.

Space-based scatterometer instruments have been built before, but much of what makes ISS-RapidScat unusual is how it came to be. "Space Station Program Manager Michael Suffredini offered us a mounting location on the space station and a free ride on a SpaceX Dragon cargo resupply mission launching in early 2014," explained Howard Eisen, the ISS-RapidScat project manager at JPL. "So we had about 18 months to put together an entire mission."

This accelerated timeline is a blink of an eye at NASA, where the typical project is years or decades in the making.

Free ride

Next, Eisen and his team turned to getting creative and crafty with the mission's hardware. In lieu of using newly-designed instruments, which would be expensive and take too long to develop, ISS-RapidScat reuses leftover hardware originally built to test parts of the QuikScat mission. That process involved dusting off and testing pieces of equipment that hadn't seen the light of day since the 1990s. Fortunately the old hardware seems ship-shape and ready to go. "Even though they were spares, they've done an excellent job so far," said Simon Collins, ISS-RapidScat's instrument manager at JPL. Despite their age, the old parts are more than capable of collecting the ocean wind data that ISS-RapidScat need to be a success.

In addition to old spare parts, some new hardware was needed to interface this instrument to the space station and the Dragon spacecraft. ISS-RapidScat will use off-the-shelf, commercially-available computer hardware instead of the expensive, hardened-against-radiation computer chips that are typically used in space missions. "If there's an error or something because of radiation, all we have to do is reset the computer. It's what we call a managed risk," said Eisen. The radiation environment on the space station is much less severe than that experienced en route to Mars, for example, or in more traditional sun-synchronous orbits.

Science bounty

Cost-saving decisions like this are shaping up to make ISS-RapidScat an exceptional bargain of a space mission. "We're doing things differently, and we're trying to do them quickly and cheaply," said Eisen. Considering that the typical launch alone can cost $200 million, ISS-RapidScat's estimated $26 million price tag seems like a bargain. Last year, NASA estimated the cost of a new, free-flying scatterometer satellite mission at approximately $400 million.

The real challenges of getting ISS-RapidScat into space lie in the details. One of the major headaches of such a hurried schedule has been getting the special connectors that will allow ISS-RapidScat to physically attach to the International Space Station. "They're special robotically-mated connectors that haven't been made in years," Eisen said. "We're having to convince the company that produces these connectors to make us a small run in time for the mission, and it hasn't been easy."

The logistics of operating an instrument on the space station are also tricky. "Typically, spacecraft are designed for the instruments they carry," said Collins. "In this case, it's the other way around." For example, ISS-RapidScat's docking point on the space station faces outward toward space -- not down toward Earth and the ocean that the instrument is looking at. The space station's flying angle will also change as new pieces are added to it, in response to changes in the station's drag profile. ISS-RapidScat's mount can compensate for both of these challenges.

Another concern the ISS-RapidScat team confronted early on was that one of the space station's docking ports lies squarely within the field of view of the scatterometer. "Bombarding astronauts and visiting supply vehicles with microwave radiation from the instruments was out of the question, and turning the instrument off when there were things docked there would take away too much science," explained Collins. The project's engineers instead devised a plan where the instrument avoids irradiating docking vessels, but continues to scan across the vast majority of its viewing range.

Rodr?guez is confident that the reward for overcoming such difficulties will be a bounty of vital science information. "Because it uses much of the same hardware QuikScat did, ISS-RapidScat will allow us to continue the observations of ocean winds already started," said Rodriguez. "Extending this data record will help us observe and understand weather patterns and improve our preparedness for tropical cyclones."

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