Early Saturday morning, the United Launch Alliance will send up its most powerful rocket, the Delta IV Heavy, along with a spacecraft bound for the Sun. On top of the rocket is NASA’s Parker Solar Probe, embarking on the first ever mission into the Sun’s atmosphere, known as the corona. Thanks to a big lift from the Delta IV, the Parker Solar Probe will get closer to the Sun than any human-made vehicle has been before — a mere 4 million miles away.
Getting to the Sun is actually super difficult. That’s because the Earth is moving sideways relative to the Sun at about 67,000 miles per hour, according to NASA. In order to journey to the center of the Solar System, the Parker Solar Probe will basically have to cancel out that speed by moving in the opposite direction to Earth. The vehicle needs a lot of power when it launches. That’s where the Delta IV Heavy comes in.
This particular Delta IV Heavy will have even more thrust than usual. The rocket, which consists of three rocket cores strapped together, sports a special third stage on top of its center booster from Northrop Grumman. It’s a stage that runs on solid rocket propellant, designed to give an extra boost to the spacecraft to put it on its path to the Sun.
But Parker will get even more boosts on its journey. Over the course of its seven year mission, it will perform seven flybys of Venus, using the planet’s gravity to go even faster and spiral in closer toward the center of the Solar System. Eventually, Parker will clock a speed of 430,000 miles per hour, making it the fastest moving space vehicle by far. The next fastest vehicle was Helios 2, another spacecraft meant to study the Sun, that reached a speed of more than 220,000 miles per hour when it moved away from Earth.
Once in the Sun’s corona — a region that reaches more than 3 million degrees Fahrenheit — Parker will study the energetic particles in the region to solve the mysteries about this area of the Solar System. For one thing, the corona is about 300 times hotter than the surface of the Sun, which doesn’t make much sense to researchers. Additionally, the corona is constantly breaking away from the Sun, flowing outward and bathing the planets in the Solar System. NASA wants to know how that happens.
The Delta IV Heavy carrying Parker is slated for liftoff at 3:33AM ET from Cape Canaveral, Florida. The rocket has a 65-minute launch window, so it can take off until 4:38AM ET. So far weather looks like it should cooperate, as there’s a 70 percent chance of favorable conditions, according to the 45th Space Wing, which oversees launches from Florida. NASA’s coverage of the launch will begin at 3AM ET.