Nestled atop a United Launch Alliance Delta IV Heavy - one of the world's most powerful rockets - with a third stage added, Parker Solar Probe will blast off toward the Sun with a whopping 55 times more energy than is required to reach Mars.
The probe is created to plunge into the Sun's mysterious atmosphere, known as the corona, coming within 3.83 million miles (6.16 million kilometres) of its surface during a seven-year mission.
The car-sized probe is created to give scientists a better understanding of solar wind and geomagnetic storms that risk wreaking chaos on Earth by knocking out the power grid. The forecast shows a 60 per cent chance of favourable weather conditions for the launch.
The Delta 4 Heavy's countdown ran into problems before fueling late Saturday, prompting ULA to delay the launch from 3:33 a.m. Saturday to 3:53 a.m.
The probe is set to use seven Venus flybys over almost seven years to gradually reduce its orbit around the Sun, using instruments created to image the solar wind and study electric and magnetic fields, coronal plasma and energetic particles.
The mission is expected to shatter a number of records: It will approach seven times closer to the sun than any other manmade object ever has, and it will be Nasa's fastest spacecraft, reaching top speeds of over 400,000 miles per hour (643737 kmh - fast enough, as Nasa's website says, to get from Washington, DC, to Philadelphia in less than one second).
The probe is protected by a 4in-thick shield that constantly repositions itself between the sun's power and the scientific instruments on board.
Scientists also hope the probe can help them to answer why the corona, the outermost layer of the sun's atmosphere, is 300 times hotter than its surface.
"The sun is full of mysteries", said Nicky Fox, project scientist at the Johns Hopkins University Applied Physics Lab.
It is created to withstand heat of up to 1,000 degrees Celsius, speeds of 700,000 kilometres per hour and a journey that will last seven years.
In addition, physicists don't know what's driving the solar wind, the supersonic stream of charged particles constantly blasting away from the sun.
Parker, now 91, recalled that at first some people did not believe in his theory.
"Parker Solar Probe uses Venus to adjust its course and slow down in order to put the spacecraft on the best trajectory", said Driesman. The shield took more than a decade to develop and 18 months to build.
The probe is set to become the fastest-moving manmade object in history.