But if all goes according to plan, the probe will launch at 3:31 a.m. ET Sunday from Cape Canaveral, Florida, on a United Launch Alliance Delta IV Heavy rocket, one of the world's most powerful rockets.
Set to launch early Saturday, the Parker Solar Probe is as heat-resistant as a spacecraft gets, essential for exploring our star closer than ever before.
The heat shield is built to withstand radiation equivalent up to about 500 times the Sun's radiation here on Earth.
The probe will fly through the sun's corona to gather data on the sun's great mysteries, such as the solar winds that create aurorae on Earth and disrupt satellites and power grids.
The launch of the probe, which will be carried on the back of a United Launch Alliance Delta IV Heavy rocket, is now scheduled to take place on Sunday morning.
The problem with a helium pressurization system could not be resolved in the 10 minutes left in the launch window, forcing ULA to order a 24-hour delay.
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.
Bairstow and Woakes put England in strong position
On the stroke of lunch, the impressive Shami picked up his second wicket with a ball that kept low and cannoned into Root's pads. Pope's wicket left the hosts on 77 for three, with two experience batsmen at the crease in Root and Jonny Bairstow.
Chris Smalling: Manchester United are eyeing Premier League glory this season
However, a move did not materialise and Mourinho must now work with the same central defensive setup as he did last season. As part of that deal, Croatia midfielder Mateo Kovacic has also joined Chelsea on a season-long loan deal.
Perseid meteor shower peaks Saturday, Sunday nights
Both nights this weekend will be great to view the meteor shower and the best viewing will be after midnight Saturday and Sunday. No special equipment is needed, but if you want the best view, it helps to be as far from artificial light as possible.
Parker's lightweight heat shield is just 4 ½ inches (11 centimeters) thick. The spacecraft is created to fly through the sun's super-hot outer atmosphere, called the corona, to study the solar wind and sun storms.
Even in a region where temperatures can reach more than a million degrees Fahrenheit, the sunlight is expected to heat the shield to just around 2,500 deg F (1,371 deg C).
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).
"We are ready. We have the flawless payload".
The tools on board will measure the expanding corona and continually flowing atmosphere known as the solar wind, which solar physicist Eugene Parker first described in 1958. Vindication came with NASA's Mariner 2 spacecraft in 1962.
When it nears the Sun, the probe will travel rapidly enough to go from NY to Tokyo in one minute - some 430,000 miles per hour, making it the fastest human-made object.