GRACE, standing for GRAVITY RECOVERY AND CLIMATE EXPERIMENT, is a space mission conducted by the NASA.
GRACE contains 2 identical spacecraft, flying 220 kilometers apart in polar orbit, 500 kilometers above planet Earth. This costed $98 Million.
Launched in the March of 2002, GRACE was the second of NASA Earth Science Pathfinder Program started in May of 1997. Simply put, it's job is to accurately map variations in Earth's gravity field. It does this through use of GPS and microwave ranging systems. Changes in gravity will affect one of the two satellites, thus changing the distance and speed between them. Scientists calculate this, and can then create gravity maps of this information. This system is accurate to 10 microns--about one-tenth the width of a human hair.
The gravity variations studied by GRACE include:
Changes due to surface and deep currents in the ocean;
Runoff and ground water storage on land masses
Exchanges between ice sheets or glaciers and the ocean;
Variations of mass within Earth.
Here is a model of GRACE:
Oribiting Earth 16 times a day, GRACE produces details maps of Earth's gravity field and aids the work of scientists that use space technology.
For example, GRACE's output may be used for satellite altimetry, and radio interferometry. This data can then be used in a variety of branches, including: oceanography, hydrology, glaciology, geology and other related disciplines.
"GRACE marks the first launch of NASA's Earth System Science Pathfinder program,designed to develop new measurement technologies for studying our Earth system," said Dr. Ghassem Asrar, associate administrator for NASA's Earth Science Enterprise, NASA Headquarters, Washington. "Through NASA's continuing investment in technology development, we've been able to create an innovative mission at a fraction of the cost of missions formulated just a decade ago. GRACE will provide us with a new view of our home planet and help us to better understand climate change and its global impacts such as changes in sea level and the availability of water resources."
Ultimately, GRACE can be used for predicting climate change and global warming, finding weather patterns, locating natural resources, and exploring places nobody has dared to visit before.
There are already a number of things GRACE has been used to discover, for example:
1. Ground-water: Hydrologist Matt Rodell of NASA's Goddard Space Flight Center, Greenbelt, Maryland have found more and more locations where humans are pumping out groundwater faster than it is replenished. So, Rodell and his team provide GRACE data on deep soil moisture and groundwater to the National Drought Mitigation Center each week, using a hydrology model to describe how the moisture is changing throughout the month between one map and the next. This data is used in preparing weekly maps of U.S. drought risk.
2. Antarctica is one of the world's toughest places to collect data, and Greenland isn't far behind. However, it is crucial to know how fast these ice sheets are melting to better understand rates and variations of sea level rise around the world. Since GRACE launched, its measurements show Greenland has been losing about 280 gigatons of ice per year on average -- a bit less than twice the weight of Mt. Everest -- and Antarctica has lost slightly under 120 gigatons a year. It is dire that we take measures to battle this.
3. The sea level is rising both because melting ice from land is flowing into the ocean and because seawater is expanding as it warms. With GRACE, scientists are able to distinguish between changes in water mass and changes in ocean temperatures. For example, a study led byCarmen Boening, whichexplained a significant drop in sea level with the 2011 La Niña event. The study showed that the water that left the ocean, causing the drop in sea level, was rained out over Australia, South America and Asia. The finding gave scientists a new view on the global water cycle.
4. The viscous mantle under Earth's crust is also moving ever so slightly in response to mass changes from water near the surface. Measurements like these can provide unprecedented insights into what is happening far below Earth’s surface in big quakes such as the 2004 Sumatra event and 2011 Tohuku (Japan) quake, both of which caused devastating tsunamis.
1. Prediction of natural disasters such as Earthquakes, Tsunamis, and Weather phenomenons.
2. A single satellite image can be used to analyse and make conclusions on a variety of topics.
3. Inaccessible regions can be accessed, and scavanged, being used to make interesting discoveries.
1. Can be fairly expensive at the large scale. Launching -> Usage, capturing data, and communicating to Earth -> Management/Repairing.
2. Requires specially trained workforce to use and analyse data from the satellite. This also leads to human error, which can result very dramatically.
In comparison, there are not many disadvantages to using a machine with so simple an idea as GRACE.
Overall, GRACE is one of the most influential missions NASA has ever conducted. Upcoming, NASA will launch the GRACE-FO project, due to the original GRACE running out of battery. GRACE-FO is planned to be used to further research global water cycles, and extend the legacy of the GRACE by a decade.
It is my opinion that the UN's involvement in Space missions would greatly increase it's productivity scale, effectiveness and efficiency. It has been done several times, like this, but it can be done even better in a global perspective.
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