A last-minute technical hitch forced controllers at the Florida space centre to cancel the night-time launch of the Parker Solar Probe, announcing that they would try again on Sunday.
The Parker probe will have tools to measure the sun's expanding corona and its flowing atmosphere known as the solar wind, which was first discovered by solar physicist Eugene Parker in 1958.
The red pressure alarm for the gaseous helium system had gone off.
"Launch teams will attempt to launch on Sunday morning", NASA said in a tweet on Saturday.
The launch time is 3:31 am EDT.
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 was scheduled to take off from Florida's Cape Canaveral at 9.28am United Kingdom time, but just one minute and 55 seconds before launch it was cancelled after a technical fault.
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 project, with a $1.5 billion price tag, is the first major mission under Nasa's Living With a Star program.
This is a phenomenon that has baffled NASA scientists because the sun's atmosphere "gets much, much hotter the farther it stretches from the sun's blazing surface".
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. The shield took more than a decade to develop and 18 months to build.
The goal for the Parker Solar Probe is to make 24 passes through the corona during its seven-year mission.
"And it needs to be, because it takes an vast amount of energy to get to our final orbit around the Sun", Driesman added.
A $1.5 billion Parker Solar Probe mission will fly through the sun's outer atmosphere within 6.4 million km of the very big hot star repeatedly, gathering key insights about solar structure, activity, atmosphere, solar winds and other features. The names were uploaded to a memory drive that is being carried by the probe.