Ahead of the historic launch on August 4, the shield was installed on June 27 to keep the spacecraft from being burnst to a crisp.
The probe will go within 4 million miles of the sun, which has never been visisted by a human-made spacecraft - approximately 25 million miles closer than Mercury itself ever gets.
The Thermal Protection System is a rounded "carbon-carbon composite sandwiching a lightweight carbon foam core", while the sield has also been sprayed with "a specially formulated white coating to reflect as much of the Sun's energy away from the spacecraft as possible".
It means the shield will stop the core from being exposed to intense temperatures hitting almost 2,500 degrees Fahrenheit - around 1,370 degrees Celsius.
NASA expects that the instruments "will be kept at a relatively comfortable temperature of about 85 degrees Fahrenheit".
If the mission is a success and the spacecraft faces the heat of the solar system's star, it will be aiming to sample the corona and teach scientists more about "the inner workings" of the sun.