Coastal Sentries Watch The Sea

National Data Buoy Center Credit: NOAA


Deep-ocean Assessment and Reporting of Tsunamis (DART®)                           Description

DART Tsunami Technology logo

For DART® realtime data, click here.


To ensure early detection of tsunamis and to acquire data critical to real-time forecasts, NOAA has placed Deep-ocean Assessment and Reporting of Tsunami (DART®) stations at sites in regions with a history of generating destructive tsunamis. NOAA completed the original 6-buoy operational array (map of original six stations) in 2001 and expanded to a full network of 39 stations in March, 2008.

Originally developed by NOAA, as part of the U.S. National Tsunami Hazard Mitigation Program (NTHMP), the DART® Project was an effort to maintain and improve the capability for the early detection and real-time reporting of tsunamis in the open ocean. See DART® development for more info.

DART® presently constitutes a critical element of the NOAA Tsunami Program. The Tsunami Program is part of a cooperative effort to save lives and protect property through hazard assessment, warning guidance, mitigation, research capabilities, and international coordination. NOAA’s National Weather Service (NWS) is responsible for the overall execution of the Tsunami Program. This includes operation of the U.S. Tsunami Warning Centers (TWC) as well as leadership of the National Tsunami Hazard Mitigation Program. It also includes the acquisition, operations and maintenance of observation systems required in support of tsunami warning such as DART®, local seismic networks, coastal, and coastal flooding detectors. NWS also supports observations and data management through the National Data Buoy Center (NDBC).

System Overview

NOAA Tsunami Buoy


DART® systems consist of an anchored seafloor bottom pressure recorder (BPR) and a companion moored surface buoy for real-time communications (Gonzalez et al., 1998). An acoustic link transmits data from the BPR on the seafloor to the surface buoy.

The BPR collects temperature and pressure at 15-second intervals. The pressure values are corrected for temperature effects and the pressure converted to an estimated sea-surface height (height of the ocean surface above the seafloor) by using a constant 670 mm/psia. The system has two data reporting modes, standard and event. The system operates routinely in standard mode, in which four spot values (of the 15-s data) at 15-minute intervals of the estimated sea surface height are reported at scheduled transmission times. When the internal detection software (Mofjeld) identifies an event, the system ceases standard mode reporting and begins event mode transmissions. In event mode, 15-second values are transmitted during the initial few minutes, followed by 1-minute averages. Event mode messages also contain the time of the initial occurrence of the event. The system returns to standard transmission after 4 hours of 1-minute real-time transmissions if no further events are detected.

The first generation DART® (DART I) systems had one-way communications from the BPR to the Tsunami Warning Centers (TWC) and NDBC via the western Geostationary Operational Environmental Satellite (GOES West) (Milburn et al., 1996). DART I became operational in 2003. NDBC replaced all DART I systems with the second generation DART® systems (DART II) in early 2008. DART I transmits standard mode data once an hour (four estimated sea-level height observations at 15-minute intervals). For information about the development of DART® technology, click here.

DART II became operational in 2005 (Green, 2006). A significant capability of DART II is the two-way communications between the BPR and the TWCs/NDBC using the Iridium commercial satellite communications system (Meinig et al., 2005). The two-way communications allow the TWCs to set stations in event mode in anticipation of possible tsunamis or retrieve the high-resolution (15-s intervals) data in one-hour blocks for detailed analysis. DART II systems transmit standard mode data, containing twenty-four estimated sea-level height observations at 15-minute intervals, once very six hours. The two-way communications allow for real-time troubleshooting and diagnostics of the systems. The DART® buoys have two independent and redundant communications systems. NDBC distributes the data from both transmitters under separate transmitter identifiers. NDBC receives the data from the DART II systems, formats the data into bulletins grouped by ocean basin (see the NDBC – DART® GTS Bulletin Transmitter List, for a listing of the bulletin headers used for each transmitted identifier), and then delivers them to the National Weather Service Telecommunications Gateway (NWSTG) that then distributes the data in real-time to the TWCs via NWS communications and nationally and internationally via the Global Telecommunications System.

For more information about tsunamis, including the U.S. warning system and information on how to prepare for one, visit the NOAA website at  NOAA tsunami website.

Credit:  U.S. Dept. of Commerce
National Oceanic and Atmospheric Administration
National Weather Service
National Data Buoy Center
Bldg. 3205
Stennis Space Center, MS 39529

Cassini Data Points to Liquid Ocean on Titan

The colorful globe of Saturn's largest moon, Titan, passes in front of the planet and its rings in this true color snapshot from NASA's Cassini spacecraft. Image credit: NASA/JPL-Caltech/Space Science Institute

 Full image and caption 

PASADENA, Calif. — Data from NASA’s Cassini spacecraft have revealed Saturn’s moon Titan likely harbors a layer of liquid water under its ice shell.

Researchers saw a large amount of squeezing and stretching as the moon orbited Saturn. They deduced that if Titan were composed entirely of stiff rock, the gravitational attraction of Saturn would cause bulges, or solid “tides,” on the moon only 3 feet (1 meter) in height. Spacecraft data show Saturn creates solid tides approximately 30 feet (10 meters) in height, which suggests Titan is not made entirely of solid rocky material. The finding appears in today’s edition of the journal Science.

“Cassini’s detection of large tides on Titan leads to the almost inescapable conclusion that there is a hidden ocean at depth,” said Luciano Iess, the paper’s lead author and a Cassini team member at the Sapienza University of Rome, Italy. “The search for water is an important goal in solar system exploration, and now we’ve spotted another place where it is abundant.”

Titan takes only 16 days to orbit Saturn, and scientists were able to study the moon’s shape at different parts of its orbit. Because Titan is not spherical, but slightly elongated like a football, its long axis grew when it was closer to Saturn. Eight days later, when Titan was farther from Saturn, it became less elongated and more nearly round. Cassini measured the gravitational effect of that squeeze and pull.

Scientists were not sure Cassini would be able to detect the bulges caused by Saturn’s pull on Titan. By studying six close flybys of Titan from Feb. 27, 2006, to Feb. 18, 2011, researchers were able to determine the moon’s internal structure by measuring variations in the gravitational pull of Titan using data returned to NASA’s Deep Space Network (DSN).

“We were making ultrasensitive measurements, and thankfully Cassini and the DSN were able to maintain a very stable link,” said Sami Asmar, a Cassini team member at NASA’s Jet Propulsion Laboratory in Pasadena, Calif. “The tides on Titan pulled up by Saturn aren’t huge compared to the pull the biggest planet, Jupiter, has on some of its moons. But, short of being able to drill on Titan’s surface, the gravity measurements provide the best data we have of Titan’s internal structure.”

This artist's concept shows a possible scenario for the internal structure of Titan, as suggested by data from NASA's Cassini spacecraft. Image credit: A. Tavani

Full image and caption

An ocean layer does not have to be huge or deep to create these tides. A liquid layer between the external, deformable shell and a solid mantle would enable Titan to bulge and compress as it orbits Saturn. Because Titan’s surface is mostly made of water ice, which is abundant in moons of the outer solar system, scientists infer Titan’s ocean is likely mostly liquid water.

On Earth, tides result from the gravitational attraction of the moon and sun pulling on our surface oceans. In the open oceans, those can be as high as two feet (60 centimeters). While water is easier to move, the gravitational pulling by the sun and moon also causes Earth’s crust to bulge in solid tides of about 20 inches (50 centimeters).

The presence of a subsurface layer of liquid water at Titan is not itself an indicator for life. Scientists think life is more likely to arise when liquid water is in contact with rock, and these measurements cannot tell whether the ocean bottom is made up of rock or ice. The results have a bigger implication for the mystery of methane replenishment on Titan.

“The presence of a liquid water layer in Titan is important because we want to understand how methane is stored in Titan’s interior and how it may outgas to the surface,” said Jonathan Lunine, a Cassini team member at Cornell University, Ithaca, N.Y. “This is important because everything that is unique about Titan derives from the presence of abundant methane, yet the methane in the atmosphere is unstable and will be destroyed on geologically short timescales.”

A liquid water ocean, “salted” with ammonia, could produce buoyant ammonia-water liquids that bubble up through the crust and liberate methane from the ice. Such an ocean could serve also as a deep reservoir for storing methane.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The mission is managed by JPL for NASA’s Science Mission Directorate in Washington. DSN, also managed by JPL, is an international network of antennas that supports interplanetary spacecraft missions and radio and radar astronomy observations for the exploration of the solar system and the universe. The network also supports selected Earth-orbiting missions. Cassini’s radio science team is based at Wellesley College in Massachusetts. JPL is a division of the California Institute of Technology in Pasadena.

For more information about the mission, visit: and .

Jia-Rui Cook 818-354-0850
Jet Propulsion Laboratory, Pasadena, Calif.

Dwayne Brown 202-358-1726
NASA Headquarters, Washington

Liftoff of the NROL-15


UPDATE  09:15:  Liftoff successful.

Delta IV Heavy to Launch NROL-15

Rocket/Payload:  A Delta IV Heavy configuration will launch the National Reconnaissance Office (NRO) NROL-15 mission.

Date/Launch Time/Site: Friday, June 29,  from Space Launch Complex (SLC)-37 at Cape Canaveral Air Force Station, Fla. Launch is planned for 6:13 a.m. EDT.

Launch Notes:  NROL-15 is the third of four planned launches for the NRO in 2012, and the second of three NRO launches in just six weeks..

Mission Description: The mission will be launched for the National Reconnaissance Office in support of national defense.

Viewing the Launch Online: A live simulcast of the launch broadcast will begin at 5:53 a.m. EDT.

Go Delta! Go NROL-15!

Giant Arc Discovered Behind Massive Galaxy Cluster

These images, taken by NASA's Hubble Space Telescope, show an arc of blue light behind an extremely massive cluster of galaxies residing 10 billion light-years away. Image credit: NASA/ESA/University of Florida, Gainsville/University of Missouri-Kansas City/UC Davis

Full image and caption

Hubble Space Telescope Credit: NASA

PASADENA, Calif. — Seeing is believing, except when you don’t believe what you see. Astronomers using NASA’s Hubble Space Telescope have found a puzzling arc of light behind an extremely massive cluster of galaxies residing 10 billion light-years away. The galactic grouping, discovered by NASA’s Spitzer Space Telescope, was observed as it existed when the universe was roughly a quarter of its current age of 13.7 billion years.

Spitzer Space Telescope Credit: NASA

The giant arc is the stretched shape of a more distant galaxy whose light is distorted by the monster cluster’s powerful gravity, an effect called gravitational lensing. The trouble is, the arc shouldn’t exist.

“When I first saw it, I kept staring at it, thinking it would go away,” said study leader Anthony Gonzalez of the University of Florida in Gainesville, whose team includes researchers from NASA’s Jet Propulsion Laboratory, Pasadena, Calif. “According to a statistical analysis, arcs should be extremely rare at that distance. At that early epoch, the expectation is that there are not enough galaxies behind the cluster bright enough to be seen, even if they were ‘lensed,’ or distorted by the cluster. The other problem is that galaxy clusters become less massive the further back in time you go. So it’s more difficult to find a cluster with enough mass to be a good lens for gravitationally bending the light from a distant galaxy.”

Galaxy clusters are collections of hundreds to thousands of galaxies bound together by gravity. They are the most massive structures in our universe. Astronomers frequently study galaxy clusters to look for faraway, magnified galaxies behind them that would otherwise be too dim to see with telescopes. Many such gravitationally lensed galaxies have been found behind galaxy clusters closer to Earth.

The surprise in this Hubble observation is spotting a galaxy lensed by an extremely distant cluster. Dubbed IDCS J1426.5+3508, the cluster is the most massive found at that epoch, weighing as much as 500 trillion suns. It is 5 to 10 times larger than other clusters found at such an early time in the history of the universe. The team spotted the cluster in a search using NASA’s Spitzer Space Telescope in combination with archival optical images taken as part of the National Optical Astronomy Observatory’s Deep Wide Field Survey at the Kitt Peak National Observatory, Tucson, Ariz. The combined images allowed them to see the cluster as a grouping of very red galaxies, indicating they are far away.

This unique system constitutes the most distant cluster known to “host” a giant gravitationally lensed arc. Finding this ancient gravitational arc may yield insight into how, during the first moments after the Big Bang, conditions were set up for the growth of hefty clusters in the early universe.

The arc was spotted in optical images of the cluster taken in 2010 by Hubble’s Advanced Camera for Surveys. The infrared capabilities of Hubble’s Wide Field Camera 3 helped provide a precise distance, confirming it to be one of the farthest clusters yet discovered.

Once the astronomers determined the cluster’s distance, they used Hubble, the Combined Array for Research in Millimeter-wave Astronomy (CARMA) radio telescope, and NASA’s Chandra X-ray Observatory to independently show that the galactic grouping is extremely massive.

Coma Cluster Credit: NASA/JPL-Caltech/GSFC/SDSS

“The chance of finding such a gigantic cluster so early in the universe was less than one percent in the small area we surveyed,” said team member Mark Brodwin of the University of Missouri-Kansas City. “It shares an evolutionary path with some of the most massive clusters we see today, including the Coma cluster and the recently discovered El Gordo cluster.”

El Gordo Cluster Credit: NASA's Chandra X-ray Observatory in blue, along with optical data from the European Southern Observatory's Very Large Telescope (VLT) in red, green, and blue, and infrared emission from the NASA's Spitzer Space Telescope in red and orange.

An analysis of the arc revealed that the lensed object is a star-forming galaxy that existed 10 billion to 13 billion years ago. The team hopes to use Hubble again to obtain a more accurate distance to the lensed galaxy.

The team’s results are described in three papers, which will appear online today and will be published in the July 10, 2012 issue of The Astrophysical Journal. Gonzalez is the first author on one of the papers; Brodwin, on another; and Adam Stanford of the University of California at Davis, on the third. Daniel Stern and Peter Eisenhardt of JPL are co-authors on all three papers.

JPL manages the Spitzer Space Telescope mission for NASA’s Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at the California Institute of Technology in Pasadena. Data are archived at the Infrared Science Archive housed at the Infrared Processing and Analysis Center at Caltech. Caltech manages JPL for NASA. For more information about Spitzer, visit and .

Whitney Clavin 818-354-4673
Jet Propulsion Laboratory, Pasadena, Calif.

Donna Weaver / Ray Villard 410-338-4493 / 338-4514
Space Telescope Science Institute, Baltimore, Md. /

The Evolution of a Tropical Cyclone

NASA's Aqua satellite passed over Tropical Storm Debby when she became a tropical storm on June 23 as she continued to organize and strengthen. Infrared data from the AIRS instrument onboard, indicated the bulk of showers and thunderstorms stretched from the north to the east and southern quadrants. Credit: NASA/JPL, Ed Olsen

Tropical Storm Debby formed from the low pressure area called System 96L, that NASA satellites were studying last week. NASA’s Aqua satellite flew over the storm right after it strengthened into a tropical storm on June 23.

Debby was born Saturday, June 23 around 4 a.m. EDT as her maximum sustained winds whipped up to 50 mph very quickly. She was born about 220 miles (355 km) south-southeast of the mouth of the Mississippi River, near 26.2 North and 87.6 West. Debby was moving to the north at 6 mph (9 kmh).

A large band of intense rain (darker red) lies just off shore, while light (blue areas) to moderate rain covers a broad area of the Florida peninsula.Moderate rain (shown in green) north and east of the center extends from near Tampa Bay all the way around to near Panama City. Tornado symbols mark the locations of tornado reports. Credit: SSAI/NASA, Hal Pierce

In an infrared image taken on June 23 from the Atmospheric Infrared Sounder (AIRS) instrument on NASA’s Aqua satellite, the bulk of showers and thunderstorms (heaviest rainfall and strongest t-storms) were seen north, east and south of the center of circulation. That triggered heavy rainfall, flash flooding and isolated tornadoes in Florida this weekend.

By the next day, Sunday June 24 at 8 a.m. EDT, Debby’s maximum sustained winds were near 60 MPH (95 kmh), and Debby was located about 170 miles (270 km) southeast of the mouth of the Mississippi River. That’s about 195 miles southwest of Apalachicola, Fla. Debby slowed to a crawl in a northerly direction at 2 mph (4 kmh).

By early Monday, June 25, Debby was almost stationary in the Gulf of Mexico bringing heavy rain, storm surge, tropical-storm-force winds to several Gulf states. Watches and warnings on June 25 include: A tropical storm warning for east of the Alabama-Florida border eastward to the Suwannee River, Florida. A tropical storm watch is also in effect for south of the Suwannee River to Englewood Florida.

Text Credit: Rob Gutro
NASA Goddard Space Flight Center, Greenbelt, Md.

Capt Dave’s note:  Debby finally made landfall near Cedar Key, Florida on June 26 and is thought to be moving east toward the Atlantic.  Let’s hope so.

Orion Ready For Final Assembly

Readying Orion for Flight


The NASA team at the Michoud Assembly Facility in New Orleans has completed the final weld on the first space-bound Orion capsule. The Exploration Flight Test 1 (EFT-1) Orion will be shipped to the Kennedy Space Center for final assembly and checkout operations.

The EFT-1 flight will take Orion to an altitude of more than 3,600 miles, more than 15 times farther away from Earth than the International Space Station. Orion will return home at a speed of 25,000 miles, almost 5,000 miles per hour faster than any human spacecraft. It will mimic the return conditions that astronauts experience as they come home from voyages beyond low Earth orbit. As Orion reenters the atmosphere, it will endure temperatures up to 4,000 degrees F., higher than any human spacecraft since astronauts returned from the moon.

Image Credit: NASA/Eric Bordelon

Living Organisms Survive Exposure in Space


Cladonia bellidiflora. Photo by Karen Dillman, U.S. Forest Service.

Lichen Survive in Space: Space Station Research Sheds Light On Origin of Life

Lichens are a part of our everyday life.  They are found most everywhere. On rocks, pathways, trees, rooftops, and can be very beautiful.

ISS Astronauts and Scientists can attest to the hardiness of the lichen.

You can freeze it, thaw it, vacuum dry it and expose it to radiation, but still life survives. ESA’s research on the International Space Station is giving credibility to theories that life came from outer space — as well as helping to create better sunscreens.

In 2008 scientists sent the suitcase-sized Expose-E experiment package to the Space Station filled with organic compounds and living organisms to test their reaction to outer space.
When astronauts venture on a spacewalk, hours are spent preparing protective suits to survive the hostile conditions. No effort was made to protect the bacteria, seeds, lichen and algae attached to the outside of the Space Station, however.
“We are exploring the limits of life,” explains ESA’s René Demets.
Our atmosphere does a wonderful job of protecting life on Earth by absorbing harmful UV rays and keeping temperatures relatively stable.
In contrast, the space samples endured the full power of the Sun’s rays. The samples were insulated somewhat by the Space Station but still had to cope with temperatures changing from -12ºC to +40ºC over 200 times as they orbited Earth.
The samples returned to Earth in 2009 and the results have now been published in a special issue of the journal Astrobiology.
Lichen have proven to be tough cookies — back on Earth, some species continue to grow normally.
René explains, “These organisms go into a dormant state waiting for better conditions to arrive.”
The lichen have attracted interest from cosmetic companies. They can survive the full power of the Sun for 18 months, so knowing more could lead to new ingredients for sunscreen.
Living organisms surviving in open space supports the idea of ‘panspermia’ — life spreading from one planet to another, or even between solar systems.
It seems possible that organisms could colonize planets by hitching rides on asteroids. ESA is probing this intriguing theory further on future Station missions with different samples.

For additional pictures and information on lichens, go to the U.S. Forestry web site:  and, the Astrobiology Journal at:

Story Source:  European Space Agency.