A $US340 million deep-space observatory that aims to alert people on earth of potentially dangerous solar activity and geomagnetic storms has blasted off on top of a SpaceX Falcon 9 rocket.
Experts say the DSCOVR - a joint collaboration of the US Air Force, NASA and the National Oceanic and Atmospheric Administration - will help the preparation and response to space weather, thereby protecting utilities, consumers and industries.
It is headed to a destination between the earth and sun known as Lagrangian point, or L1.
The journey will take 110 days, followed by 40 days of instrument tests.
"The Falcon takes flight, propelling the Deep Space Climate Observatory on a million mile journey to protect our planet earth," said NASA commentator George Diller as the rocket took off from Cape Canaveral, Florida, at 6.03pm on Wednesday (1003 AEDT Thursday).
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Space weather is the primary objective of the five-year mission, although the initial idea for the satellite came from former US vice president Al Gore, who dreamed of a spacecraft that would observe earth and send back live images that would raise environmental awareness of the planet's fragility.
"It was inspiring to witness the launch," Gore said in a statement shortly afterwards.
"DSCOVR has embarked on its mission to further our understanding of earth and enable citizens and scientists alike to better understand the reality of the climate crisis and envision its solutions."
Its secondary mission is to collect scientific data about aerosol levels, ozone and radiation balance on Earth.
Meanwhile, California-based SpaceX said high seas off the coast of Florida had forced it to abandon another planned attempt at recycling its rocket by flying the first stage of the Falcon 9 to a controlled landing on an ocean platform, known as a drone ship.
