MIAMI - SpaceX counted down Sunday to the launch of its unmanned Dragon cargo ship toward the International Space Station, carrying food, supplies and experiments for growing lettuce in space.
The launch is scheduled for 10:21 am (1421 GMT) from Cape Canaveral, Florida, where the skies were clear and posed little risk of any weather delay.
After liftoff, the California-based company headed by Internet entrepreneur Elon Musk will make a third try at making a controlled, upright landing of its Falcon 9 rocket on an ocean platform.
Two previous attempts have failed, but SpaceX says the goal is to perfect the technology in order to eventually save millions of dollars on each launch by making recyclable rockets that are as reusable as airplanes.
Currently, rockets fall to pieces in the ocean after blasting their cargo to space, wasting valuable equipment and damaging the marine environment.
Cargo for astronauts
The Dragon capsule is carrying 4,000 pounds (1,800 kilograms) of gear to the space station, including a large parking space, known as an International Docking Adaptor, designed to make it easier for an array of commercial spacecraft to dock at the orbiting lab in the future.
The gear is the first of two adaptors that will be affixed to the US side of the space station.
The cargo ship is also carrying dozens of science experiments, including one that will allow astronauts to grow their own greens - both Tokyo Bekana cabbage and Red Romaine lettuce.
Another experiment devised by middle school students aims to study how worms behave in a compost pile in space.
With longer, deep space missions planned for the future to Mars or an asteroid, scientists are keen to figure out how space travelers will be able to grow their own food in distant places where fresh produce is impossible to get.
The cargo ship should arrive at the space station on Tuesday and will stay for five weeks, before returning to Earth August 5.
Three men are currently living at the space station, including Russian cosmonaut Mikhail Kornienko and American astronaut Scott Kelly who began their year-long mission in orbit back in March.
The station commander, Russian cosmonaut Gennady Padalka, arrived with them but is only staying six months.
Padalka, 57, however, set a new world record on Sunday, when he became the person who has officially spent the longest amount of cumulative time in space - 804 days.
His career includes one trip to the Mir Space Station and four to the ISS.
"Padalka has travelled roughly the equivalent of four trips to Mars during his time aboard the International Space Station," said NASA commentator George Diller.
Padalka has now made 12,848 orbits of Earth, for a total distance of 339,870,899 miles (546,969,192 kilometers), Diller said.