Miami - SpaceX said it cannot attempt to recycle the first stage of its Falcon 9 rocket after launch of a space weather observatory on Wednesday because of high seas.
The launch from Cape Canaveral, Florida of the $340m Deep Space Climate Observatory (DSCOVR), is planned for 18:03, after a series of delays due to weather and radar failures.
But after the launch, rather than trying to guide the elongated first stage of the Falcon 9 back to a floating ocean platform, SpaceX will just attempt to control its descent -- in a so-called "soft landing" -- before allowing it to fall into the Atlantic Ocean.
"Unfortunately we will not be able to recover the first stage of the Falcon 9," said SpaceX in a statement.
"The drone ship was designed to operate in all but the most extreme weather. We are experiencing just such weather in the Atlantic with waves reaching up to three stories in height crashing over the decks."
The California-based company headed by Internet tycoon Elon Musk also said just three of the powered platform's four engines are functioning.
"The rocket will still attempt a soft landing in the water through the storm [producing valuable landing data] but survival is highly unlikely."
SpaceX is embarking on a series of rocket-landing tests with the goal of one day making rockets as reusable as airplanes, instead of allowing them to fall to pieces into the ocean after launch.
Meanwhile, the primary mission of the launch is to replace an aging space weather satellite with a new deep space observatory that will collect data on solar flares and geomagnetic storms.
The unmanned DSCOVR is a sun-observing spacecraft that was initially dreamed up by former US vice president Al Gore.
In its 1990s incarnation, the spacecraft's goal was to observe the Earth. The administration of George W Bush cancelled the mission. Nasa kept the equipment in storage, and brought it out about seven years ago.
Instruments were added and others were refurbished, to make the spacecraft into a tool to help space weather forecasters by collecting data on solar wind and geomagnetic storms that can cause damage to electrical systems on Earth.
Its secondary mission is to collect scientific data about aerosol levels, ozone and radiation balance on Earth.
DSCOVR -- a joint collaboration of the US Air Force, Nasa and the National Oceanic and Atmospheric Administration (Noaa) -- is headed to a point about one million miles from Earth, a destination known as Lagrangian point, or L1.
The journey will take 110 days, followed by 40 days of instrument tests.