07.19.07

A NASA researcher has developed a new method to anticipate food shortages brought on by drought. Molly Brown of NASA’s Goddard Space Flight Center in Greenbelt, Md., and her colleagues created a model using data from satellite remote sensing of crop growth and food prices.

Brown conceived the idea while working with organizations in Niger, West Africa, that provide information regarding failed crops and help address local farmers' worries about feeding their families. Brown's new approach could improve the ability for government and humanitarian aid officials to plan and respond to drought-induced food price increases in Niger and elsewhere.

Supply and demand largely dictate food prices, with greater supply leading to lower prices and less supply leading to higher prices. During a food crisis in semi-arid regions like Niger, food shortages are often brought on when lack of rainfall significantly reduces the amount of grain farmers are able to grow. Farmers in regions like Niger are able only to grow a few drought-resistant crops, and therefore must buy grain at unaffordably high prices at the end of the year to make up for shortfalls in production. This scenario could drive a drought-driven food security crisis. A lack of locally-produced and affordable grain, coupled with increased prices and reduced access to food, could lead to starvation and hunger-related illness in the most vulnerable segments of society.

Images right: The left image shows how dry season climate browns millet crops in a farmer's field when compared to the right image taken during the Wet season when millet crops grow green and lush in the same farmer's field. The images illustrate the stark differences between crops that receive adequate rainfall and those that do not, whether in countries like Senegal (where photos were taken) or in countries like Niger. Credit: Molly Brown/NASA

Brown, the lead author of a study to be published early next year in the journal Land Economics, said that until now officials have primarily studied the after effects of occurrences like floods or droughts that might affect crop production as their best means of warning of a coming food security crisis. "With this new study, for the first time we can leverage satellite observations of crop production to create a more accurate price model that will help humanitarian aid organizations and other decision makers predict how much food will be available and what its cost will be as a result. This is a unique opportunity for an economic model to take climate variables into account in a way that can aid populations large and small," she said.

Agricultural economists often use a mathematical formula and typically data on crop yield, a range of market prices, and other variables to develop a price model that estimates what food prices may be in the marketplace. Brown applied remote-sensing data in an economic model producing an enhanced way for aid officials to combat a problem that affects 3.6 million people in Niger alone.

To use their price model in a real-world situation, Brown and her colleagues compared variations in crop production to variations in food prices in parts of West Africa. They focused on a sample crop, a drought-resistant grain called millet. Locally, people use millet to create a couscous-like dish. Brown's team observed the June-September wet season to the October-May dry season – and the amount and growth rate of green vegetation. Then, it studied how seasonal climate differences affected the crop’s price in local markets.

Image left: Farmers sell their millet crops at outdoor markets like this one in Senegal. Credit: Molly Brown/NASA

Brown used long-term data from sensors on NASA-built satellites to gauge the density of local plant life, an indicator of the strength of the crop. From space, sensors pick up reflections from the ground to determine the ground’s “greenness” and enable researchers to estimate the amount of rainfall. Those data in turn may be used to estimate the amount of grain that crops will produce. Brown combined the satellite data and climate variables with the price model to create maps of millet prices covering a complete area. With these maps decision makers can predict price changes, food availability and ultimately food insecurity.

Food prices are not determined solely by human action. Climate variables affect about 20 percent of the process of market pricing, according to the study's co-author Jorge Pinzon, a research scientist and mathematician at Goddard. This is a factor that decision makers often do not take into account when analyzing food security, Pinzon said.

"It is critical to include climate and environmental variables in food security planning when piecing together all of the forces that come together to create famine," said Pinzon. "This model can help officials better understand the role that climate plays in food availability and pricing, and also in famine warning when applied to a real-time planning effort."

Brown believes that information provided by this new technique can aid organizations that are part of the U.S. Agency for International Development's (USAID) Famine Early Warning System to stem suffering that occurs every year from food crises. Brown hopes that her method, funded by NASA and USAID, may eventually help the farmers in Niger more effectively plan what to grow and when to grow it to earn a living wage.

"This price model can be used in any region of the world where there are seasonal climate factors that can contribute to local food production crises," said Brown. "Even a country with normally adequate food production can still experience a food crisis if a drought hits. We hope that decision makers will work together with scientists to apply this model so that even a farmer on a small plot of land can better sustain his family during a drought."

ESA’s Venus Express and NASA’s MESSENGER booked an appointment at Venus late in the evening of 5 June, to look at the oddities of this mysterious planet in tandem for a few hours. Just a few weeks on, scientists from both teams are ready to present a first set of images.

Image right: As NASA’s MESSENGER departed from Venus on 5 June 2007 to continue its journey towards Mercury, its Wide Angle Camera captured a sequence of 50 images (480-nm wavelength filter) showing the planet disappearing in the distance. Initially, images were acquired at a rate of one of every 20 minutes and then, with increasing distance, the timing interval was increased to 60 minutes. Click image to view movie. Credit: NASA/APL

This unique opportunity to make multi-point observations of the Venusian atmosphere was possible thanks to the MESSENGER (MErcury Surface, Space ENvironment, Geochemistry, and Ranging) swingby of Venus – a key step during its long journey to Mercury - while Venus Express was already orbiting the planet in the course of its mission.

The two spacecraft carry sets of instruments employing different observation techniques which complement each other. The data collected at Venus are now being analysed by teams on both sides of the Atlantic and, as can be appreciated in the first images presented here, already hints at the potential of the results to come.

The particular orbital geometry of Venus Express when MESSENGER skimmed past Venus on 5 June meant that the two spacecraft were not at the same location (with respect to the surface of the planet) at the exact same time.

VIRTIS Image of the Area Overflown by MESSENGER

Image left: This grey-scale image, obtained by the VIRTIS instrument on board ESA’s Venus Express, shows the atmospheric region of Venus over which NASA’s MESSENGER passed on 5 June 2007. The region of MESSENGER’s closest approach is in the night side (marked by a circle). Credits: ESA/VIRTIS/INAF-IASF/Obs. de Paris-LESIA

MESSENGER made its closest approach at a distance of about 338 km from the planet over the planetary coordinates 12.25° South and 165° East, on the night side of the planet. Meanwhile, Venus Express was behind the horizon, almost right above the South Pole, at about 35 000 km from Venus.

So how could they make true joint observations of the same regions and phenomena? Scientists came up with a highly creative solution.

Two Hunters for the Same Cloud

The scientists used a computer simulation based on real atmospheric data about Venus obtained from previous ground and space observations. Knowing the speed of the local winds, which depend both on the altitude and the latitude, they were able to predict where a particular set of clouds would be at a given point in time.

For their observation, the Venus Express scientists selected a cloud that – moving west by about 90° longitude every day - was visible to Venus Express and would be in view of MESSENGER 12 hours later, at the time of its closest approach. The same cloud became visible again for Venus Express 12 hours after MESSENGER’s closest approach, this time on the night-side.

VIRTIS Images of the Clouds That MESSENGER Flew Over

Click image for high resolution copy

Image above: The images in this panel were obtained by the VIRTIS imaging spectrometer on board Venus Express on 5 and 6 June 2007, before and after MESSENGER’s closest approach to the planet. These panels from VIRTIS provide a night-side view of the same region that Messenger flew over and imaged. The images where obtained at 1.7 micrometres, revealing atmospheric details down to an altitude of 50 km from the surface. Credit: NASA/JHUAPL

The VIRTIS imaging spectrometer on board Venus Express probed this cloud (top row of this image composite) at several wavelengths. These observations provided a view of the cloud at about 45-50 km altitude (bottom row) from the planet. The clouds below the point of closest approach can be seen in the top row.

The Mercury Laser Altimeter (MLA) instrument on board MESSENGER probed the same cloud structure at 50-75 km from the surface, like VIRTIS.

Such an observation – a typical example of atmospheric structure at Venus – with cross-sections obtained at different altitudes and with different instruments, is a unique opportunity for researchers hoping to solve the puzzle of the Venusian atmosphere’s dynamics and composition.

Cloud Structures at Venus at Time of MESSENGER Flyby

Image right: This movie consists of a sequence of six images obtained by the VIRTIS imaging spectrometer on board ESA’s Venus Express on 5 and 6 June 2007, before and after NASA MESSENGER’s closest approach to the planet. The image sequence, obtained by VIRTIS, provides a night-side view of the same region that Messenger flew over and imaged. Click image to view animated GIF. Credits: ESA/VIRTIS/INAF-IASF/Obs. de Paris-LESIA

Over about 24 hours, not only did the two spacecraft observe the same clouds, but MESSENGER also flew closely over the atmospheric region. Again, these dual-spacecraft, multi-instrument observations may provide additional atmospheric details.

Thermal and Radar Maps of Venus’ Surface Compared

Image above: An unprocessed thermal map of the Venusian surface obtained by VIRTIS on 5 June 2007 (left) is compared here with a radar image of the same area obtained by NASA’s Magellan spacecraft in the 1990s (right). Correlations between topographic and thermal data similar to the ones shown in this image-composite will allow the scientists to understand if the measured temperature of the surface depends only on the altitude – where higher altitudes simply corresponds to colder, temperatures such as on Earth – or if it depends on the presence of previously undetected sources of heat such as active volcanoes. Credits: Left panel: ESA/VIRTIS/INAF-IASF/Obs. de Paris-LESIA, Right panel: NASA

A spectacular view obtained by VIRTIS (left), in the region of MESSENGER's closest approach to Venus provides, even if still unprocessed, a ‘thermal view’ of the Venusian surface. The image is compared here with an image of the same feature synthesized by data from NASA’s Magellan spacecraft in the 1990s (right).

Magellan provided radar imaging and altimetry maps, providing information on the topography (elevation) and the radar reflectivity of the surface. Venus Express’ VIRTIS is providing ‘thermal maps’ of the surface containing information on the emissivity in the infrared. Correlations between topographic and thermal data similar to the ones shown here, will allow scientists to understand if the measured temperature of the surface depends on the altitude – where ‘higher’ simply corresponds to ‘colder’ – or if it depends on the presence of previously undetected sources of heat, such as active volcanoes or other geological activities.

Image left: ESA’s Venus Express, in orbit around Venus since 11 April 2006, was joined for a few hours by NASA’s MESSENGER spacecraft, flying by Venus while on its way to Mercury. This animation shows both the Venus Express and MESSENGER spacecraft in orbit around Venus at the time of the fly-by. Earth-based observatories and telescopes in orbit around Earth were also watching. Looking at Venus together, spacecraft and ground observatories obtained a unique set of data each, so many different ‘eyes’ observed the same regions and phenomena during the same time frame. Click image to view animation. Credit: NASA/APL

The Venus Express and MESSENGER scientists are now continuing the analysis of this rich and complex set of data collected at Venus. The data also involve several other instruments studying not only Venus’ cloud deck and surface, but also the plasma environment, magnetic fields, and the atmospheric oxygen airglow.

More mature results from this joint observation campaign are expected by the end of the year.


Mike Buckley
Johns Hopkins Applied Physics Lab

07.19.07

Scientists have recently discovered that the planet Saturn is turning 60 - not years, but moons.

"We detected the 60th moon orbiting Saturn using the Cassini spacecraft's powerful wide-angle camera," said Carl Murray, a Cassini imaging team scientist from Queen Mary, University of London. "I was looking at images of the region near the Saturnian moons Methone and Pallene and something caught my eye."

Image right: Sixtieth moon to be discovered at Saturn, indicated in red. Image credit: NASA/JPL/Space Science Institute
+ Moon animation (700Kb - GIF)
+ Full image and caption

The newly discovered moon first appeared as a very faint dot in a series of images Cassini took of the Saturnian ring system on May 30 of this year. After the initial detection, Murray and fellow Cassini imaging scientists played interplanetary detective, searching for clues of the new moon in the voluminous library of Cassini images to date.

The Cassini imaging team's legwork paid off. They were able to locate numerous additional detections, spanning from June 2004 to June 2007. "With these new data sets we were able to establish a good orbit for the new moon,” said Murray. "Knowing where the moons are at all times is important to the Cassini mission for several reasons."

One of the most important reasons for Cassini to chronicle these previously unknown space rocks is so the spacecraft itself does not run into them. Another reason is each discovery helps provide a better understanding about how Saturn's ring system and all its billions upon billions of parts work and interact together. Finally, a discovery of a moon is important because with this new knowledge, the Cassini mission planners and science team can plan to perform science experiments during future observations if and when the opportunity presents itself.

What of this new, 60th discovered moon of Saturn? Cassini scientists believe "Frank" (the working name for the moon until another, perhaps, more appropriate one is found) is about 1.2 miles (2 kilometers) wide and, like so many of its neighbors, is made mostly of ice and rock. The moon's location in the Saturnian sky is between the orbits of Methone and Pallene. It is the fifth moon discovered by the Cassini imaging team.

"When the Cassini mission launched back in 1997, we knew of only 18 moons orbiting Saturn," said Murray. "Now, between Earth-based telescopes and Cassini we have more than tripled that number - and each and every new discovery adds another piece to the puzzle and becomes another new world to explore."

Murray and his colleagues may get the chance to explore Saturn's 60th moon. The Cassini spacecraft's trajectory will put it within 7,300 miles (11,700 kilometers) in December of 2009.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, Calif., manages the Cassini-Huygens mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging team is based at the Space Science Institute, Boulder, Colo.

Related news releases:
+ Science and Technology Facilities Council
+ Cassini Imaging Team