Florida: Atop three columns of flame at 3:31 a.m. Eastern time, NASA’s Parker Solar Probe lifted toward space from Cape Canaveral, Florida on Sunday. The second launch of the spacecraft went off right on time, after glitches interrupted Saturday morning’s first try.
The spacecraft — which NASA touts will one day “touch the sun” — is on top of a Delta IV Heavy rocket built and operated by United Launch Alliance, a joint venture between Boeing and Lockheed Martin.
— NASA (@NASA) August 12, 2018
The main constraint on the launch time is to get the spacecraft to its first rendezvous with Venus in November. At this hour, the launchpad is pointed in the right direction to get to Venus.
It takes a lot of energy to get to the sun — more than 50 times as much as it takes to reach Mars, NASA explains. That is because Earth is moving fast in its orbit around the sun — 67,000 miles per hour. In order for the spacecraft to spiral inward, it has to shed some of that energy, and that means launching at high speed in the direction opposite to Earth’s motion.
The spacecraft is small, about the size of a car and weighing 1,400 pounds, but there is a third stage to give an additional velocity boost.
Another constraint is making sure that the spacecraft passes as quickly as possible through the Van Allen belt, a region around Earth of intense radiation. The radiation can scramble the spacecraft’s electronics. Those considerations also helped dictate when the launch window begins and ends.