Solar Probe Plus will orbit the Sun 24 times, gradually "walking in" toward the Sun with each pass. The closest points of each orbit come well within orbit of Mercury – the closest planet to the Sun.
On the final three orbits, Solar Probe Plus will fly to within 8.5 solar radii of the Sun's "surface" 8.5 solar radii is 8.5 times the radius of the Sun, or about 3.7 million miles. That is about seven times closer than the current record-holder for a close solar pass, the Helios spacecraft.
At closest approach, Solar Probe Plus will be hurtling around the Sun at approximately 450,000 miles per hour! That's fast enough to get from Philadelphia to Washington, D.C., in one second.
Solar Probe Plus will pass Venus less than two months after launch and will be collecting science data at its first solar pass just one month later.
At closest approach to the Sun, while the front of Solar Probe Plus' solar shield faces temperatures approaching 2,600° Fahrenheit (or 2,000° Celsius), the spacecraft's payload will be at room temperature.
