2002 EARTH SCIENCE VIDEOTAPES |
| |
Tape Title | Record ID | Date Produced | TRT: |
Synopsis |
| AMAZING GRACE - THE BEST LOOK YET AT EARTH'S INVISIBLE GRAVITY FIELD
| G02-002 | 3/7/02 | 00:20:00 | Gravity - it's the unseen hand that roots humanity firmly to the ground and helps control the motion of the oceans. It's a force of nature like no other, working to pull two masses together. Just like the life it plants on the surface of the Earth, gravity is ever changing. When mass moves within the planet's atmosphere, ocean, land, or frozen surface (cryosphere), the gravity field moves as well. NASA's Gravity Recovery and Climate Experiment (GRACE), launching in March 2002, will give scientists around the globe the most accurate look yet at the face of gravity and how it shapes our world.
|
TAPE CONTENTS: |
| ITEM (1): Clearly Unique: The Invisible World of Gravity (Reporter Pac w/vo) - Strange and abstract, yet vaguely familiar. Could this lumpy, bumpy object really be our orbiting home in the galaxy? While the human eye is more familiar with Earth in its blue marble form, NASA's Gravity Recovery and Climate Experiment shakes off the cloaking exterior and takes a peek at Earth's invisible gravity field.
Gravity. According to physics, gravity is the force of nature that pulls two masses together, But in reality, it is the unseen hand that roots humanity firmly to the ground and helps control the motion of the oceans. It is a force of nature like no other, and just like the life it plants to the surface, gravity is forever changing.
Nicknamed GRACE, NASA's newest spacecrafts to take orbit will map Earth's gravity field more accurately than ever before. Since mass is uneven within the Earth, GRACE sees a lumpy, bumpy portrait of our planet. GRACE scientists will develop new gravity maps every thirty days from which researchers across the globe can benefit.
Not just a vehicle carrying science instruments, GRACE is a science tool. Designed as twin spacecrafts, the GRACE units are connected only by a microwave beam. As one unit approaches an area of higher gravity, it speeds up and increases the distance between the satellites. The global positioning system will pinpoint the distance between the spacecrafts, resulting in the gravity measurements.
GRACE will help us understand the structure of our Earth better, from its land to its water, its air to its oceans. The mission will aid in studies of climate change, sea level rise, the water cycle, and global weather prediction. GRACE is an amazing new way to look at our planet. Credit: NASA
|
| ITEM (2): Clearly Unique: The Invisible World of Gravity (Reporter Pac wo/vo)
|
| ITEM (3): Amazing GRACE - GRACE is actually two identical spacecraft that will fly about 200 kilometers apart, connected only by a microwave signal. As they orbit the Earth, the spacecraft are pulled by areas of higher and lower gravity and will move in relation to one another. As the front satellite approaches an area of higher gravity, it will be pulled toward that higher gravity and speed up, increasing the distance between the two spacecraft. As GRACE straddles the area of higher gravity, the trailing satellite will speed up but the front satellite will slowdown. HAIRS, the high accuracy intersatellite ranging system will measure the distance changes between the spacecraft. New maps of Earth's gravity field will be produced every thirty days based on distance measurements between the two spacecraft. Credit: NASA
|
| ITEM (4): GRACE in Action - We don't reside on a flat planet as we perceive from our daily activities. Earth appears neat and round from space, but take a look at the planet from GRACE's perspectiveŠThe bumps and lumps seen in the next animation are the result of an uneven distribution of mass inside the Earth. Mass varies between mountains, valleys, oceans, and caverns, which means gravity varies in these areas as well. GRACE will map out the precise location of these lumps, enabling greater understanding of the structure of the Earth. Credit: NASA/USFS
|
| ITEM (5): Taking Our Lumps - GRACE gravity data will provide scientists a monthly view of Earth that looks like the following animation. Land features like mountains and valleys cause differences in the gravity field, but they are not the only creators of this bumpy view of Earth. Changes in the ocean, like El Nino events, runoff and ground water storage on land masses, exchanges between ice sheets, glaciers, and the oceans and many other subtle changes can alter the gravity field. Understanding gravity better might help us predict changes in our planet. Credit: NASA/USFS
|
| ITEM (6): GRACE and the Land - When gravity changes in one area, it could be due to the movement of water on or beneath the surface. GRACE's measurements of this change help us to understand how water moves from the oceans to lakes, land and rivers and back again, as in the global water cycle. In the following water cycle animation, sunlight is absorbed by the ocean and the energy is used to evaporate water. Water vapor then rises into the sky, where the condensation releases energy into the atmosphere. Water drops fall back to Earth and the cycle repeats itself. Credit: NASA
|
| ITEM (7): GRACE and Ice - GRACE will measure changes in mass over Earth's great ice sheets, such as Antarctica. This information will aid scientists in determining if these areas are changing in size. Knowledge of mass variation is key to understanding the effects of climate change on sea level rise. This animation shows the retreat of the Western Antarctic ice sheet. It begins with Antarctica as it is today, then morphs to depict changes in the Antarctic ice sheet since the peak of the last ice age - nearly 20,000 years ago. The animation then morphs again to show current conditions. The West Antarctic ice sheet has lost nearly 2/3 of it's mass during this period - a volume sufficient to raise sea level 33 feet. Credit: NASA
|
| ITEM (8): GRACE and the Oceans - Tides may be controlled by the moon's gravity, but they have an impact on Earth's gravity as well. As the tides move, mass redistributes in the ocean. Scientists will compare GRACE measurements over the ocean with measurements of sea surface height to study sea level changes. In this animation, scientists derived a 16-day set of predictive data from the TOPEX/JASON mission to show how tides might move around the world's oceans. Blue signifies places where the ocean level is lower than the average reference height, and red shows areas where it's higher. The difference is significant: between the darkest blue and the brightest red is a range of more than 15 meters, displaced by lunar tidal forces. White areas separating the blues and reds approximate the "zero" point, a reference sea level against which other areas are compared. Credit: NASA
|
| ITEM (9): GRACE B-Roll - GRACE is an international collaboration between NASA, DLR (German Space Agency), and the University of Texas. The spacecraft was assembled and tested in Germany, and will launch from Plesetsk, Russia. Credit: NASA/DLR
|
| ITEM (10): Interview With - Primary Investigator, Dr. Byron Tapley, University of Texas Credit: NASA
|
Earth Science Gallery