NASA launches Parker Solar Probe in its first mission to the Sun

NASA launched its historic small car-size probe to "touch the Sun" from Cape Canaveral Air Force Station in Florida on Sunday. Its scheduled launch on Saturday got scrubbed as NASA cited the cause of delaying the launch as a "violation of a launch limit".

"The launch of a United Launch Alliance Delta IV Heavy rocket carrying the Parker Solar Probe spacecraft was scrubbed today due to a violation of a launch limit, resulting in a hold. There was not enough time remaining in the window to recycle," NASA said in a blog post.

"The forecast shows a 60 per cent chance of favourable weather conditions for launch," the post added.

The probe is named after Eugene Parker, a solar physicist who in 1958 first predicted the existence of the solar wind, the stream of charged particles and magnetic fields that flow continuously from the Sun.

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.

Weighing just 635 kgs, it is a relatively light spacecraft, Andy Driesman, project manager for the mission at the Johns Hopkins University Applied Physics Laboratory in the US, said in an earlier statement issued by NASA.

"And it needs to be, because it takes an immense amount of energy to get to our final orbit around the Sun," Driesman added.

Zooming through space in a highly elliptical orbit, the Parker Solar Probe will reach speeds of up to 700,000 kms per hour, setting the record for the fastest spacecraft in history.

During its nominal mission lifetime of just under seven years, the Parker Solar Probe will complete 24 orbits of the Sun -- reaching within 3.8 million miles of the Sun's surface at the closest approach.

In an orbit this close to the Sun, the real challenge is to keep the spacecraft from burning up.

"Recent advances in materials science gave us the material to fashion a heat shield in front of the spacecraft not only to withstand the extreme heat of the Sun, but to remain cool on the backside," said Adam Szabo, the mission scientist for the Parker Solar Probe at NASA's Goddard Space Flight Center in Greenbelt, Maryland.

The heat shield is made of a 4.5-inch thick carbon composite foam material between two carbon fibre face sheets.

At the Parker Solar Probe's closest approach to the Sun, temperatures on the heat shield will reach nearly 1,371 degrees Celsius, but the spacecraft and its instruments will be kept at a relatively comfortable temperature of about 29.4 degrees Celsius.