The one-hour window for liftoff of the Delta IV Heavy rocket from Cape Canaveral in Florida will end at 4:31am. (The initial launch attempt was scrubbed yesterday because of a last-minute helium-pressure problem.)
Built by United Launch Alliance, the rocket will send the Parker—a 1,500-lb. computer—on a seven-year trip that will see it reach speeds of 430,000 miles per hour. That’s faster than any human-made object has ever traveled.
You can watch NASA’s live stream of the launch here, starting at 3am ET:
The path to the sun is “the most, most challenging in all space exploration,” as Dr. Yanping Guo, the Johns Hopkins researcher who plotted the trajectory, told Quartz’s Tim Fernholz, who writes of the journey that will take the probe past Venus a record seven times:
…the Earth is orbiting the sun, and quickly—19 miles (30 kilometers) per second. Imagine being on a merry-go-round, circling quickly around a central axis. It’s a lot easier to stay in place, or be flung outward, than to climb towards the center. Those same laws of physics, described by Johannes Kepler and Isaac Newton in the 17th century, govern motion in space.
Let’s stay on our merry-go-round. The sun’s gravity is that central axis, pulling you in, which interacts with your speed around the edge, locking you into an orbit. To get to the interior of the merry-go-round—or the solar system—you must diminish your velocity so the pull from the central axis wins out.
In space, the probe will rely on solar power. The path designed by Guo has it passing closely by the sun 24 times.