Sats to weigh Earth H2O
Alien asteroid may be oldest in system
WASHINGTON, May 22, (Agencies): The reason we know today just how much ice is melting in Greenland and Antarctica is because of a pair of satellites, launched in 2002 by NASA and the German Research Centre for Geosciences (GFZ). Now, they are set to be replaced by a more modern duo.
A SpaceX Falcon 9 rocket was scheduled to blast off at 3:47 pm (1947 GMT) Tuesday from Vandenberg Air Force Base in California, hoisting into orbit the spacecraft known as GRACE-FO, a follow-on to the prior, 15-year mission known as the Gravity Recovery and Climate Experiment (GRACE).
Two satellites, each the size of a car, will circle the Earth at a distance of 137 miles (220 kilometers) from each other.
They will be flying about 310 miles (490 kilometers) above the Earth for the next five years.
According to the laws of physics, the slightest variation in mass on Earth modifies the pull of gravity on satellites.
When the lead satellite passes over a mountain, it will get slightly farther from its twin for a few instants because of the extra mass in this area and a slightly stronger pull of gravity.
These slight variations in distance will be constantly recorded by the spacecraft, because each shift signals a change in mass on the planet underneath.
The satellites use a monthly reference point, because unless there is an earthquake or other unusual event, only water has the capacity to change that fast.
Water always has mass, whether it is in the form of liquid, solid or gas.
permission from the agencies involved in the search, including the Colombian government. “We’ve been holding this under wraps out of respect for the Colombian government,” said Rob Munier, WHOI’s vice president for marine facilities and operations.
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When ice melts, the oceans’ mass rises. When it rains a lot in a certain region, the volume of the aquifers mounts. The satellites will pick this up, and the data will show that the mass in a certain area was higher than it was in the prior month, or year.
That is how the GRACE-FO satellites will establish a map of the water on Earth, every 30 days, showing which areas have more and which have less, whether above or below ground.
They operate with a precision equivalent to a change of 0.4 inches (one centimeter) in water height across areas of about 211 miles (340 kilometers) in diameter.
The prior mission, GRACE, allowed scientists to gain an understanding of how much ice Greenland was losing. It was more than they thought, based on ground-observations.
An “alien asteroid” that circles the sun in the giant gas planet Jupiter’s orbital path, but hurtling in the opposite direction, is the first-known permanent resident of our solar system that astronomers have concluded originated in another star system.
Researchers said on Monday a close examination of the asteroid’s orbit indicated it formed elsewhere and was captured by gravitational forces when our solar system — the sun, planets and various other objects — formed from a swirling cloud of gas and dust about 4.5 billion years ago.
“It is a strong candidate for the oldest object in the solar system,” said astronomer Fathi Namouni of Observatoire de la Côte d’Azur in France.