NASA Oceanography

Looking at our Earth from space, it is obvious that we live on a water planet. Ocean covers over 70% of the Earth's surface and contains about 97% of the Earth's surface water. Life in the oceans can be found from the surface to the extreme environments at the bottom of the deepest submarine trench. It is not surprising that the oceans represent over 99% of the living space on Earth...we are indeed living on what is truly an ocean planet.

Oceans & the Earth System	The Physical Ocean	The Living Ocean
Beyond our Planet	Learning Resources	Data Resources
	Oceans Interactive

Why does NASA study the ocean?

Part of NASA's mission is to develop an understanding of the total Earth system and the effects of natural and human-induced changes on the global environment. Our oceans play a major role in influencing changes in the world's climate and weather. Collecting and analyzing long-term ocean data from satellites is a relatively new field of exploration. The analysis of remotely-sensed ocean data makes it possible to understand the ocean in new and exciting ways.
Prior to satellite data, most of what we have learned about the oceans had come from infrequent measurements collected from ships, buoys, and drifters. Ship-based oceanographers are limited to sampling the ocean in a relatively small area with often a great deal of difficulty. Data from ships, buoys, and drifters are not sufficient to characterize the conditions of the spatially diverse of the ocean.

The advent of ocean-observing satellites has launched a new era of marine discovery. Remotely sensed satellite data and modeling techniques enable the global mapping of seasonal changes in ocean surface topography, currents, waves, winds, phytoplankton content, sea-ice extent, rainfall, sunlight reaching the sea, and sea surface temperature. Studying these patterns at a global scale help forecast and mitigate the disastrous effects of floods and drought. Images generated by ocean observing satellite missions tell us volumes about the most fundamental climate changes. During the last decade, forecasting models have benefited from satellite data as they have improved the ability to predict events such as El Niño and other global and regional climate cycles. These models will become more sophisticated as scientists and forecasters further develop the ability to simulate certain ocean phenomena and thus better predict when they will occur.

Using remote sensing data and computer models, scientists can now investigate how the oceans affect the evolution of weather, hurricanes, and climate. Oceans control the Earth's weather as they heat and cool, humidify and dry the air and control wind speed and direction. And the weather determines not just what you'll wear to work in the week ahead--but also whether the wheat crop in Nebraska will get enough rain to mature, whether the snow pack in the Sierras will be thick enough to water southern California, whether the hurricane season in the Atlantic will be mellow or brutal, whether eastern Pacific fisheries will be decimated by El Niño. Long-term weather patterns influence water supply, food supply, trade shipments, and property values. They can even foster the growth of civilizations, or kill them off. You can't escape the weather, or even change it--but being able to predict its caprice makes its impact manageable. And only by understanding the dynamics of the oceans can we begin to do this.

NASA has been observing the oceans from space for more than 20 years. NASA launched Seasat, the first civilian oceanographic satellite, on June 28, 1978. The satellite carried five complementary sensors designed to monitor the oceans from space. These sensors included:
 

• a radar altimeter to measure spacecraft height above the ocean surface
• a microwave scatterometer to measure wind speed and direction
• a scanning multichannel microwave radiometer to measure sea surface temperature
• a visible and infrared radiometer to identify cloud, land and water features
• a synthetic aperture radar to monitor the global surface wave field and polar sea ice conditions

 
Although a massive short-circuit in its power system ended all data-taking operations after only 105 days, the Seasat instruments provided as much oceanographic data as had been acquired by ships in the previous 100 years! The variables that Seasat measured in its short lifetime are some of the most important for understanding the ocean and its role in climate.

Another satellite, Tiros-N, was also launched in 1978. It carried the first AVHRR sensor which produced the first really useful maps of sea-surface temperature, and the Coastal Zone Color Scanner, that produced the first maps of chlorophyll and primary productivity in the ocean.

Today there are several ocean-observing satellite missions and an extensive scientific research community studying these data. Each mission provides its own unique contribution to our knowledge of the ocean, however our understanding is rapidly evolving such that we are coming to more fully understand the role that each parameter plays in the constantly changing conditions and cycles of the ocean and thus on climate and weather.

Ocean Exploration at NASA

NASA is the exploration agency of the Federal Government. NASA Earth observing satellites often open up new vistas for Earth science research. All are meant to explore the envelope of what is known and understood about the physical, chemical and biological processes of the planet

Earth

New Report: Responding to the Challenge of Climate and Environmental Change
NASA's Plan for a Climate-Centric Architecture for Earth Observations and Applications from Space
Earth is a complex, dynamic system we do not yet fully understand. The Earth system, like the human body, comprises diverse components that interact in complex ways. We need to understand the Earth's atmosphere, lithosphere, hydrosphere, cryosphere, and biosphere as a single connected system. Our planet is changing on all spatial and temporal scales. The purpose of NASA's Earth science program is to develop a scientific understanding of Earth's system and its response to natural or human-induced changes, and to improve prediction of climate, weather, and natural hazards.

This is a composite image of the North African Continent. A dust storm can be seen blowing off the coast of Morocco in the northwest corner.
Image: MODIS band combination 1,4,3.

A major component of NASA’s Earth Science Division is a coordinated series of satellite and airborne missions for long-term global observations of the land surface, biosphere, solid Earth, atmosphere, and oceans. This coordinated approach enables an improved understanding of the Earth as an integrated system. NASA is completing the development and launch of a set of Foundational missions, new Decadal Survey missions, and Climate Continuity missions.
The Foundational missions are those missions in development at the time the decadal survey was published and include Aquarius, NPOESS Preparatory Project (NPP), Landsat Data Continuity Mission (LDCM), and Global Precipitation Measurement (GPM). The Decadal Survey missions are those guided by the decadal survey produced by the National Research Council of the National Academy of Sciences and published in 2007. These missions include Soil Moisture Active-Passive (SMAP), Ice, Cloud and land Elevation Satellite (ICESat-II), Hyperspectral Infrared Imager (HyspIRI), Active Sensing of CO₂ Emissions Over Nights, Days, and Seasons (ASCENDS), Surface Water and Topography (SWOT), Geostationary Coastal and Air Pollution Events (GEO-CAPE), and Aerosol-Clouds-Ecosystems (ACE). Earth Venture, also a recommendation of the decadal survey, consists of low cost, competed suborbital and orbital missions as well as instruments for Missions of Opportunity.The Climate Continuity missions include Orbiting Carbon Observatory-2 (OCO-2), Stratospheric Aerosol and Gas Experiment – III (SAGE III), Gravity Recovery and Climate Experiment Follow-on (GRACE-FO), and Pre-Aerosol, Clouds, and Ocean Ecosystem (PACE).
Over the coming decades, NASA and the Agency's research partners will continue to pioneer the use of both spaceborne and aircraft measurements to characterize, understand, and predict variability and trends in Earth's system for both research and applications. Earth is the only planet we know to be capable of sustaining life. It is our lifeboat in the vast expanse of space. Over the past 50 years, world population has doubled, grain yields have tripled and economic output has grown sevenfold. Earth science research can ascertain whether and how the Earth can sustain this growth in the future. Also, over a third of the US economy - $3 trillion annually - is influenced by climate, weather, and natural hazards, providing economic incentive to study the Earth.
NASA Earth System Science conducts and sponsors research, collects new observations, develops technologies and extends science and technology education to learners of all ages. We work closely with our global partners in government, industry, and the public to enhance economic security, and environmental stewardship, benefiting society in many tangible ways. We conduct and sponsor research to answer fundamental science questions about the changes we see in climate, weather, and natural hazards, and deliver sound science that helps decision-makers make informed decisions. We inspire the next generation of explorers by providing opportunities for learners of all ages to investigate the Earth system using unique NASA resources, and our Earth System research is strengthening science, technology, engineering and mathematics education nationwide.

Big Asteroid Tumbles Harmlessly Past Earth

Dec. 12, 2012: This week, NASA's Goldstone radar is tracking a large asteroid as it passes by Earth, and obtaining unusually clear images of the tumbling space rock.
"There is no danger of a collision with Earth," says Lance Benner of NASA's Near Earth Object Program. "At closest approach on Dec. 12th, asteroid 4179 Toutatis will be 7 million km away or 18 times farther than the Moon."

A sampling of Goldstone radar images obtained during the asteroid Toutatis's Dec. 2012 flyby. [more]

Asteroid Toutatis is well known to astronomers; it passes by Earth’s orbit every 4 years. Measuring 4.5 km in length, it is one of the largest known potentially hazardous asteroids (PHAs), and its orbit is inclined less than half-a-degree from Earth's. No other kilometer-sized PHA moves around the Sun in an orbit so nearly coplanar with our own.  This makes it an important target for radar studies.
NASA's Goldstone radar in the Mojave Desert will be pinging the space rock every day from Dec. 4th through 22nd.  The echoes highlight the asteroid's topography and improve the precision with which researchers know the asteroid's orbit.

"We already know that Toutatis will not hit Earth for hundreds of years," says Benner.  "These new observations will allow us to predict the asteroid's trajectory even farther into the future."
Benner and colleagues are particularly excited about a new digital imaging system at Goldstone that could reveal never-before-seen details on the asteroid's surface. "Using the new system, we can now image the asteroid's surface with 2 to 5 times finer resolution than previous flybys," he says. "We may we see something new on Toutatis."
The asteroid is already remarkable for the way that it spins. Unlike planets and the vast majority of asteroids, which rotate in an orderly fashion around a single axis, Toutatis travels through space tumbling like a badly thrown football (movie).  One of the goals of the radar observations is to learn more about the asteroid’s peculiar spin state and how it changes in response to tidal forces from the Sun and Earth.

NASA's 70-meter diameter Goldstone radar. [more]

It's probably no coincidence that the tumbling asteroid is elongated and lumpy. 
"Toutatis appears to have a complicated internal structure," says radar team member Michael Busch of the National Radio Astronomy Observatory. "Our radar measurements are consistent with the asteroid's little lobe being ~15% denser than the big lobe; and they indicate 20% to 30% over-dense cores inside the two lobes."
This raises the interesting possibility that asteroid Toutatis is actually a mash up of smaller space rocks.  "Toutatis could be re-accumulated debris from an asteroid-asteroid collision in the main belt," he says.   The new observations will help test this idea.
Busch points out that the upgraded Goldstone imaging system will produce data with a resolution of 3.75 meters per pixel.  "We'll be putting hundreds of thousands of pixels across the asteroid's surface."
What will so much resolution reveal? Stay tuned for updates from Science@NASA.

NASA Gravity Probes Prepare to Hit the Moon

Dec. 13, 2012: A pair of NASA spacecraft that have been studying the Moon's gravitational field are being prepared for a controlled descent into a mountain near the Moon's north pole.  Impact is expected at about 2:28 p.m. PST (5:28 p.m. EST) on Monday, Dec. 17.
"It is going to be difficult to say goodbye to our little robotic twins," says MIT professor Maria Zuber, principal investigator of the Gravity Recovery and Interior Laboratory (GRAIL) mission. "Planetary science has advanced in a major way because of their contributions."

This animation shows the final flight path for NASA’s twin GRAIL probes, which will hit the Moon on Dec. 17, 2012, around 2:28 p.m. PST. Play it

The two probes, named Ebb and Flow, are being sent purposely into the lunar surface because their low orbit and low fuel levels preclude further scientific operations.
Ebb and Flow's successful mission to the Moon has yielded the highest-resolution gravity field map of any celestial body. The map will provide a better understanding not only of the Moon, but also of how Earth and other rocky planets in the solar system formed and evolved.
The spacecraft have been flying in formation around the Moon since Jan. 1, 2012. They were named by elementary school students in Bozeman, Mont., who won a contest.

These 3-D comparisons depict the unnamed lunar mountain targeted by the NASA's Gravity Recovery and Interior Laboratory (GRAIL) mission for controlled impact of the Ebb and Flow spacecraft. Image credit: NASA/JPL-Caltech/MIT/GSFC

The first probe to reach the Moon, Ebb, also will be the first to go down, at 2:28:40 p.m. PST. Flow will follow Ebb about 20 seconds later. Both spacecraft will hit the surface at 3,760 mph (1.7 kilometers per second). No imagery of the impact is expected because the region will be in shadow at the time. The impact site is located near a crater named Goldschmidt.
Ebb and Flow will conduct one final experiment before their mission ends. They will fire their main engines until their propellant tanks are empty to determine precisely the amount of fuel remaining in their tanks. This will help NASA engineers validate fuel consumption computer models to improve predictions of fuel needs for future missions.
"Our lunar twins may be in the twilight of their operational lives, but one thing is for sure, they are going down swinging," said GRAIL project manager David Lehman of NASA's Jet Propulsion Laboratory in Pasadena, Calif. "Even during the last half of their last orbit, we are going to do an engineering experiment that could help future missions operate more efficiently."
Because the exact amount of fuel remaining aboard each spacecraft is unknown, mission navigators and engineers designed the depletion burn to allow the probes to descend gradually for several hours and skim the surface of the moon until the elevated terrain of the target mountain gets in their way.
The burn that will change the spacecrafts' orbit is scheduled to take place Friday morning, Dec. 14.
"Such a unique end-of-mission scenario requires extensive and detailed mission planning and navigation," said Lehman. "We've had our share of challenges during this mission and always come through in flying colors, but nobody I know around here has ever flown into a Moon mountain before. It'll be a first for us, that's for sure."

Christmas Sky Show

Dec. 21, 2012:  Just when you thought Christmas was over: At the end of the day on Dec. 25th, a pair of holiday lights will pop out of the deepening twilight. Jupiter and the Moon are having a Christmas conjunction.
It’s a beautiful apparition, visible all around the globe. Even city dwellers, who often miss astronomical events because of light pollution, can see the show. Separated by less than 2 degrees, the bright pair will beam right through urban lights.

A new ScienceCast video previews the Christmas-night conjunction of the Moon and Jupiter. Play it

For anyone who gets a telescope for Christmas, the timing is perfect. Jupiter and the Moon are among the most satisfying targets for backyard optics. A quick sweep of the telescope from Jupiter to the Moon and back again will reveal Jupiter's storms and cloud belts, the Moon's mountains and impact craters, and of course the four Galilean satellites circling the giant planet like a miniature solar system.

Jupiter's trademark Great Red Spot will also be on display--and it is worth a look. Astronomers recently announced that the enormous swirling storm, twice as wide as the planet Earth, is "spinning up."
Actually, explains planetary scientist Glenn Orton of NASA's Jet Propulsion Laboratory, "the Red Spot is shrinking." He likens it to "the iconic picture of a figure skater pulling her arms in to spin faster. As the size contracts, the spin rate increases."
John Rogers, head of the British Astronomical Association's Jupiter Section, noticed the phenomenon in recent pictures of Jupiter snapped by amateur astronomers. He was able to track a dark cloudy feature as it swirled three times around the Red Spot's central vortex. The circulating streak completed the circuit in only 4.0 days, shorter than the 4.5 days Rogers measured in 2006 using the same method.

Jupiter's Great Red Spot is spinning up. Learn more about it in the ScienceCast video Christmas Sky Show

Looking back in time, "the trend of decreasing rotation period has been consistent at least since Voyager visited Jupiter in 1979," says Rogers. As the spot shrinks, it also changes shape. Decades ago the Red Spot looked like a sausage – now it’s more circular.
What happens next is hard to say. "Perhaps the Red Spot will continue to shrink and eventually disappear," speculates Rogers. "Or perhaps it will be rejuvenated if some new storm arises to reinforce it."
One thing is certain, Christmas night is a good time to look. The Red Spot will be transiting Jupiter's middle for observers across North America and will be perfectly positioned for telescopic observations.
But you don't need a telescope to enjoy the show. Step outside at sunset on Dec. 25th and look east. After all, Christmas isn't really over until you've seen the holiday lights.

NASA to Broadcast Asteroid Flyby of Earth

Feb. 13, 2013:  NASA Television will provide commentary starting at 2 p.m. EST (11 a.m. PST) on Friday, Feb. 15, during the close, but safe, flyby of a small near-Earth asteroid named "2012 DA14." NASA places a high priority on tracking asteroids and protecting our home planet from them. This flyby will provide a unique opportunity for researchers to study a near-Earth object up close.
The half-hour broadcast from NASA's Jet Propulsion Laboratory (JPL) in Pasadena, Calif., will incorporate real-time animation to show the location of the asteroid in relation to Earth, along with live or near real-time views of the asteroid from observatories in Australia, weather permitting.

A NASA video depicts the record-setting flyby of asteroid 2012 DA14. Also, in a related blog, Bill Cooke of the Marshall Space Flight Center answers the question "Can I see the Upcoming Asteroid Flyby?"

At the time of its closest approach to Earth at approximately 2:25 p.m. EST (11:25 a.m. PST/ 19:25 UTC), the asteroid will be about 17,150 miles (27,600 kilometers) above Earth's surface. Measuring approximately 50 meters wide, 2012 DA14 is about half the size of a football field. Since regular sky surveys began in the 1990s, astronomers have never seen an object this big come so close to our planet. The asteroid will actually pass closer to Earth than many manmade satellites.
The commentary will be available via NASA TV and streamed live online at http://www.nasa.gov/ntv and http://www.ustream.tv/nasajpl2

In addition to the commentary, near real-time imagery of the asteroid's flyby before and after closest approach, made available to NASA by astronomers in Australia and Europe, weather permitting, will be streamed beginning at about noon EST (9 a.m. PST) and continuing through the afternoon at http://www.ustream.tv/nasajpl2
Also, a Ustream feed of the flyby from a telescope at NASA's Marshall Space Flight Center in Huntsville, Ala., will be streamed for three hours starting at 9 p.m. EST (8 p.m. CST). To view the feed and ask researchers questions about the flyby via Twitter, visit http://www.ustream.tv/channel/nasa-msfc

What Exploded over Russia?

Feb. 26, 2013:  When the sun rose over Russia's Ural Mountains on Friday, Feb. 15th, many residents of nearby Chelyabinsk already knew that a space rock was coming. Later that day, an asteroid named 2012 DA14 would pass by Earth only 17,200 miles above Indonesia. There was no danger of a collision, NASA assured the public.

Maybe that's why, when the morning sky lit up with a second sun and a shock wave shattered windows in hundreds of buildings around Chelyabinsk, only a few people picking themselves off the ground figured it out right away. This was not a crashing plane or a rocket attack.

"It was a meteor strike--the most powerful since the Tunguska event of 1908," says Bill Cooke of NASA's Meteoroid Environment Office.

A new ScienceCast video reviews what researchers have learned about the Russian meteor. Play it

In a coincidence that still has NASA experts shaking their heads, a small asteroid completely unrelated to 2012 DA14 struck Earth only hours before the publicized event. The impactor flew out of the blue, literally from the direction of the sun where no telescope could see it, and took everyone by surprise.
"These are rare events and it is incredible to see them happening on the same day," says Paul Chodas of NASA's near-Earth Object Program at JPL.

Researchers have since pieced together what happened. The most telling information came from a network of infrasound sensors operated by the Comprehensive Test Ban Treaty Organization (CTBTO). Their purpose is to monitor nuclear explosions.
Infrasound is a type of very low-frequency sound wave that only elephants and a few other animals can hear. It turns out that meteors entering Earth's atmosphere cause ripples of infrasound to spread through the air of our planet. By analyzing infrasound records, it is possible to learn how long a meteor was in the air, which direction it traveled, and how much energy it unleashed.

The Russian meteor's infrasound signal was was the strongest ever detected by the CTBTO network. The furthest station to record the sub-audible sound was 15,000km away in Antarctica.

Listen to the infrasound recording, sped up 135x into the range of human hearing. Play it

Western Ontario Professor of Physics Peter Brown analyzed the data: "The asteroid was about 17 meters in diameter and weighed approximately 10,000 metric tons," he reports. "It struck Earth's atmosphere at 40,000 mph and broke apart about 12 to 15 miles above Earth's surface. The energy of the resulting explosion exceeded 470 kilotons of TNT." For comparison, the first atomic bombs produced only 15 to 20 kilotons.

Based on the trajectory of the fireball, analysts have also plotted its orbit. "It came from the asteroid belt, about 2.5 times farther from the sun than Earth," says Cooke.
Comparing the orbit of the Russian meteor to that of 2012 DA14, Cooke has shown that there is no connection between the two. "These are independent objects," he says. "The fact that they reached Earth on the same day, one just a little closer than the other, appears to be a complete coincidence."

Infrasound records confirm that the meteor entered the atmosphere at a shallow angle of about 20 degrees and lasted more than 30 seconds before it exploded. The loud report, which was heard and felt for hundreds of miles, marked the beginning of a scientific scavenger hunt. Thousands of fragments of the meteor are now scattered across the Ural countryside, and a small fraction have already been found.

Preliminary reports, mainly communicated through the media, suggest that the asteroid was made mostly of stone with a bit of iron--"in other words, a typical asteroid from beyond the orbit of Mars," says Cooke. "There are millions more just like it."

And that is something to think about as the cleanup in Chelyabinsk continues.