NASA set to launch historic 'touch the Sun' spacecraft

Saturday's launch countdown was halted with just one-minute, 55 seconds remaining, keeping the Delta IV (four) rocket at Cape Canaveral, Florida, with the Parker Solar Probe.

The launch was pushed back because a technical glitch on the rocket carrying the probe, United Launch Alliance's Delta IV Heavy rocket, caused NASA to run out the clock on its 65-minute launch window Saturday.

The probe is meant to plunge into the Sun's mysterious atmosphere, known as the corona, coming within 6.16 million kilometres of its surface during a seven-year mission.

The heat shield is built to withstand radiation equivalent to up to about 500 times the Sun's radiation on Earth.

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 probe's main goal is to unveil the secrets of the corona, the unusual atmosphere around Sun.

The probe is protected by an ultra-powerful heat shield that is just 11.43 centimetres thick.

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 probe is equipped with a 4 1/2-inch thick carbon-carbon heat shield created to withstand temperatures of about 2,500 degrees Fahrenheit. The $1.5 million mission is already a week late because of rocket issues.

If everything goes according to plan, temperatures inside the spacecraft should be a mere 85 degrees Fahrenheit.

This image made available by the Johns Hopkins University Applied Physics Laboratory on Wednesday, May 31, 2017 depicts NASA's Solar Probe Plus spacecraft approaching the sun.

The corona gives rise to the solar wind, a continuous flow of charged particles that permeates the solar system. But when NASA launched its Mariner 2 spacecraft bound for Venus in 1962, it became the first robotic probe to make a successful planetary encounter, and it verified Parker's theory.

Parker said he was "impressed" by the Parker Solar Probe, calling it "a very complex machine".

"With each orbit, we'll be seeing new regions of the Sun's atmosphere and learning things about stellar mechanics that we've wanted to explore for decades", Fox added.

Vanessa Coleman