Tag: Goddard Space Flight Center

Ice Revealed in New Research

Ice Revealed in New Research
A lonely 3-mile-high (5-kilometer-high) mountain on Ceres is likely volcanic in origin, and the dwarf planet may have a weak, temporary atmosphere. These are just two of many new insights about Ceres from NASA’s Dawn mission published this week in six papers in the journal Science.

“Dawn has revealed that Ceres is a diverse world that clearly had geological activity in its recent past,” said Chris Russell, principal investigator of the Dawn mission, based at the University of California, Los Angeles.

A Temporary Atmosphere

A surprising finding emerged in the paper led by Russell: Dawn may have detected a weak, temporary atmosphere. Dawn’s gamma ray and neutron (GRaND) detector observed evidence that Ceres had accelerated electrons from the solar wind to very high energies over a period of about six days. In theory, the interaction between the solar wind’s energetic particles and atmospheric molecules could explain the GRaND observations.

A temporary atmosphere would be consistent with the water vapor the Herschel Space Observatory detected at Ceres in 2012-2013. The electrons that GRaND detected could have been produced by the solar wind hitting the water molecules that Herschel observed, but scientists are also looking into alternative explanations.

“We’re very excited to follow up on this and the other discoveries about this fascinating world,” Russell said.
Ahuna Mons as a Cryovolcano

Ahuna Mons is a volcanic dome unlike any seen elsewhere in the solar system, according to a new analysis led by Ottaviano Ruesch of NASA’s Goddard Space Flight Center, Greenbelt, Maryland, and the Universities Space Research Association. Ruesch and colleagues studied formation models of volcanic domes, 3-D terrain maps and images from Dawn, as well as analogous geological features elsewhere in our solar system. This led to the conclusion that the lonely mountain is likely volcanic in nature. Specifically, it would be a cryovolcano — a volcano that erupts a liquid made of volatiles such as water, instead of silicates. “This is the only known example of a cryovolcano that potentially formed from a salty mud mix, and that formed in the geologically recent past,” Ruesch said.

Ice Revealed in New Research
Ceres: Between a Rocky and Icy Place

While Ahuna Mons may have erupted liquid water in the past, Dawn has detected water in the present, as described in a study led by Jean-Philippe Combe of the Bear Fight Institute, Winthrop, Washington. Combe and colleagues used Dawn’s visible and

infrared mapping spectrometer (VIR) to detect probable water ice at Oxo Crater, a small, bright, sloped depression at mid-latitudes on Ceres.

Exposed water-ice is rare on Ceres, but the low density of Ceres, the impact-generated flows and the very existence of Ahuna Mons suggest that Ceres’ crust does contain a significant component of water-ice. This is consistent with a study of Ceres’ diverse geological features led by Harald Hiesinger of the Westfälische Wilhelms-Universität, Münster, Germany. The diversity of geological features on Ceres is further explored in a study led by Debra Buczkowski of the Johns Hopkins Applied Physics Laboratory, Laurel, Maryland.

Impact craters are clearly the most abundant geological feature on Ceres, and their different shapes help tell the intricate story of Ceres’ past. Craters that are roughly polygonal — that is, shapes bounded by straight lines — hint that Ceres’ crust is heavily fractured. In addition, several Cerean craters have patterns of visible fractures on their floors.

Some, like tiny Oxo, have terraces, while others, such as the large Urvara Crater (106 miles, 170 kilometers wide), have central peaks. There are craters with flow-like features, and craters that imprint on other craters, as well as chains of small craters. Bright areas are peppered across Ceres, with the most reflective ones in Occator Crater. Some crater shapes could indicate water-ice in the subsurface.

The dwarf planet’s various crater forms are consistent with an outer shell for Ceres that is not purely ice or rock, but rather a mixture of both — a conclusion reflected in other analyses. Scientists also calculated the ratio of various craters’ depths to diameters, and found that some amount of crater relaxation must have occurred. Additionally, there are more craters in the northern hemisphere of Ceres than the south, where the large Urvara and Yalode craters are the dominant features.

“The uneven distribution of craters indicates that the crust is not uniform, and that Ceres has gone through a complex geological evolution,” Hiesinger said.

Distribution of Surface Materials

What are the rocky materials in Ceres’ crust? A study led by Eleonora Ammannito of the University of California, Los Angeles, finds that clay-forming minerals called phyllosilicates are all over Ceres. These phyllosilicates are rich in magnesium and also have some ammonium embedded in their crystalline structure. Their distribution throughout the dwarf planet’s crust indicates Ceres’ surface material has been altered by a global process involving water.

Although Ceres’ phyllosilicates are uniform in their composition, there are marked differences in how abundant these materials are on the surface. For example, phyllosilicates are especially prevalent in the region around the smooth, “pancake”-like crater Kerwan (174 miles, 280 kilometers in diameter), and less so at Yalode Crater (162 miles, 260 kilometers in diameter), which has areas of both smooth and rugged terrain around it. Since Kerwan and Yalode are similar in size, this may mean that the composition of the material into which they impacted may be different. Craters Dantu and Haulani both formed recently in geologic time, but also seem to differ in composition.

“In comparing craters such as Dantu and Haulani, we find that their different material mixtures could extend beneath the surface for miles, or even tens of miles in the case of the larger Dantu,” Ammannito said.

Looking Higher

Now in its extended mission, the Dawn spacecraft has delivered a wealth of images and other data from its current perch at 240 miles (385 kilometers) above Ceres’ surface, which is closer to the dwarf planet than the International Space Station is to Earth. The spacecraft will be increasing its altitude at Ceres on Sept. 2, as scientists consider questions that can be examined from higher up.

Dawn’s mission is managed by JPL for NASA’s Science Mission Directorate in Washington. Dawn is a project of the directorate’s Discovery Program, managed by NASA’s Marshall Space Flight Center in Huntsville, Alabama. UCLA is responsible for overall Dawn mission science. Orbital ATK Inc., in Dulles, Virginia, designed and built the spacecraft. The German Aerospace Center, Max Planck Institute for Solar System Research, Italian Space Agency and Italian National Astrophysical Institute are international partners on the mission team. For a complete list of mission participants.

source: world press news

Matthew’s Total Rainfall

Matthew's Total Rainfall

NASA Adds Up Deadly Hurricane Matthew’s Total Rainfall  

A NASA rainfall analysis estimated the amount of rainfall generated by Hurricane Matthew when it moved over the Carolinas.

Hurricane Matthew dropped a lot of rain, caused flooding and deaths in the state of North Carolina. Flooding is still widespread in North Carolina.  Some rivers in North Carolina such as the Tar and the Neuse Rivers were still rising on Oct. 12.

At NASA’s Goddard Space Flight Center in Greenbelt, Maryland a rainfall analysis was accomplished using data from NASA’s Integrated Multi-satellitE Retrievals for GPM (IMERG). The GPM or Global Precipitation Measurement mission is a joint mission between NASA and the Japanese space agency JAXA.

Matthew's Total Rainfall

The Integrated Multi-satellitE Retrievals for GPM (IMERG) is a unified U.S. algorithm that provides a multi-satellite precipitation product. IMERG is run twice in near-real time with the “Early” multi-satellite product being created at about 4 hours after observation time and a “Late” multi-satellite product provided at about 12 hours after observation time.

This rainfall analysis was created using IMERG real time data covering the period from Sept. 28 through Oct. 10, 2016. The totals included some rain from a low pressure area that moved through the area near the end of September.

Hurricane Matthew’s interaction with a frontal boundary caused extreme rainfall in North Carolina resulting in over 20 inches (508 mm) of rain being reported in North Carolina. The area was already saturated before Hurricane Matthew arrived. Heavy rainfall from a slow moving low and frontal system moved through during the last week of September. Maximum rainfall total estimates for the real-time IMERG product have been adjusted to reflect observed values.

On Wednesday, Oct. 12 the National Weather Service (NWS) in Wilmington, North Carolina (NC) reported “All major area rivers will remain above flood stage throughout this upcoming week. At 10:59 a.m. EDT on Oct. 12, the North Carolina Department of Transportation reported numerous flooded roads persisting across much the coastal plain of North Carolina. This being the result of heavy rainfall totaling 5 to 12 inches across the region in the last 36 hours. Many roads are impassable, barricaded or washed away. Some neighborhoods are cut off. Swamps, creeks and rivers are still rising flooding even more areas and slowing the recession of high water. People in the warned area should not travel and be prepared for widespread flooding of a magnitude not seen in many years. If asked to evacuate please do so.”

Further south, a Flood Warning has been extended for the following rivers: Cape Fear at Elizabethtown affecting Bladen County NC; Cape Fear at Lock and Dam 1 affecting Bladen County NC; Black Creek at Quinby affecting Darlington and Florence Counties South Carolina (SC); Lynches at Effingham affecting Florence County SC.

In addition, a Flood Warning continues for the following rivers: Cape Fear at William O. Huske Lock and Dam 3 affecting Bladen County NC; Northeast Cape Fear near Burgaw affecting Pender County NC; Lumber Near Lumberton affecting Robeson County NC;  Little Pee Dee at Galivants Ferry affecting Dillon, Horry and Marion Counties,  SC;  Waccamaw at Conway affecting Horry County SC;  Great Pee Dee at Pee Dee affecting Marion and Florence Counties SC; and Black at Kingstree affecting Williamsburg County SC.

source:world press news

NASA Analyzes Heavy Rainfall

NASA Analyzes Heavy Rainfall

Slow moving frontal systems draped over Hispaniola and a tropical wave recently caused heavy rainfall that led to wide spread flooding over the northern Dominican Republic. NASA analyzed that heavy rainfall using data from satellites.

Scattered to numerous showers and scattered thunderstorms have occurred over Hispaniola during the week of Nov. 14. Hispaniola includes the Dominican Republic and Haiti.

The Global Precipitation Measurement mission or GPM core satellite can analyze rainfall rates from space. GPM is a joint mission between NASA and the Japanese space agency JAXA.

NASA’s Integrated Multi-satellite Retrievals for GPM (IMERG) were used to estimate totals for rainfall that fell over the Dominican Republic during the period from Nov. 8 to 15, 2016. IMERG data indicates that rainfall totals of greater than 230 mm (9 inches) fell over the northeastern Dominican Republic during this period. Estimates of real-time IMERG rainfall totals have been adjusted to reflect observed values in similar extreme events.

NASA Analyzes Heavy Rainfall

The Integrated Multi-satellitE Retrievals for GPM (IMERG) creates a merged precipitation product from the GPM constellation of satellites. These satellites include DMSPs from the U.S. Department of Defense, GCOM-W from the Japan Aerospace Exploration Agency (JAXA), Megha-Tropiques from the Centre National D’etudies Spatiales (CNES) and Indian Space Research Organization (ISRO), NOAA series from the National Oceanic and Atmospheric Administration (NOAA), Suomi-NPP from NOAA-NASA, and MetOps from the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT).  All of the instruments (radiometers) onboard the constellation partners are inter-calibrated with information from the GPM Core Observatory’s GPM Microwave Imager (GMI) and Dual-frequency Precipitation Radar (DPR).
On Nov. 18, the National Hurricane Center discussion noted “A stationary front extends from the west-central Atlantic near 20 degrees north latitude and 70 degrees west longitude, then along the north coast of the island to the Windward Passage continuing over the west Caribbean. A surface trough (elongated area of low pressure) is just south of the Mona Passage and coupled with the frontal boundary are generating scattered showers possible isolated thunderstorms over the Dominican Republic this morning. This front will lie across the north portion of the island through Saturday, and coupled with the surface trough moving through the central Caribbean will give the island scattered showers and possible isolated thunderstorms spreading west across the island today and will persist through Saturday.”

For information from the National Weather Service of Puerto Rico on how that system is affecting the region, go to: http://www.weather.gov/sju/

In addition to that system, a broad area of low pressure designated as System 90L in the southwestern Caribbean is also being monitored for possible tropical cyclone development by the National Hurricane Center. Very warm sea surface temperatures and upper level winds are expected to provide favorable conditions for tropical cyclone development in that area.

source: world news,press news