Atop three columns of flame at 3:31 a.m. Eastern time, NASA’s Parker Solar Probe lifted toward space on Sunday. The launch was the second attempt to carry the spacecraft, which NASA touts will “touch the sun” one day, into orbit after a scrub early on Saturday.
The probe — which will study the sun’s outer atmosphere as well as the stream of particles known as solar wind — was carried on top of a Delta IV Heavy rocket built and operated by United Launch Alliance, a joint venture between Boeing and Lockheed Martin. It is one of the most powerful rockets currently available. Its third stage gave the probe the extra kick it needs to escape Earth’s gravity at a high enough velocity to put it on course for Venus in November, and eventually the sun.
The Parker Solar Probe is designed to expand our understanding of the sun, measuring electrical and magnetic fields, cataloging the ingredients of the solar wind and photographing the corona — the outer atmosphere that is millions of degrees hotter than the sun’s surface. Instruments on the spacecraft will be able to detect details that cannot be seen from farther away, and hopefully fill in many of the blanks in human understanding of our star.
The spacecraft will eventually pass within 4 million miles of the sun’s surface, close enough to skim through the star’s outer atmosphere. Four million miles is about one-tenth the distance between the sun and Mercury, the innermost planet of the solar system.
At its closest approach, the outside of the spacecraft will reach 2,500 degrees Fahrenheit, or about the melting temperature of steel. But a 8-foot-wide carbon composite shield will absorb the intense heat and keep the spacecraft and its instruments cool. The foam in the shield is so fluffy — 97 percent empty space — that it adds only 160 pounds of weight.
Solar wind is the stream of charged particles — primarily protons and electrons — that continuously flows outward from the sun through the solar system at a speed of about a million miles per hour. Earth’s magnetic field generates a bubble that deflects the solar wind around our planet and results in the beautiful aurora borealis, also known as the Northern and Southern lights, that flicker at night in the polar regions.
Understanding the solar wind is of importance to scientists and policymakers because of its potential to devastate civilization.
Occasionally, a huge explosion, called a coronal mass ejection, erupts from the sun, sending a larger-than-usual deluge of particles into space. In 1859, one of those explosions made a direct hit on Earth, disrupting telegraph wires in America and Europe. If the same thing happened today, it could cause continentwide blackouts, potentially requiring months to years to repair.
In 2012, one of NASA’s sun-watching spacecraft, Stereo-A, detected an explosion comparable to the 1859 explosion. Fortunately, it was not aimed in Earth’s direction.
During its first plunge to the sun, the probe will pass within about 15 million miles of the sun. That’s close enough for the instruments to collect some useful data, but the greater excitement will come later.
The probe will also zip close to Venus, using that planet’s gravity as a brake to sap energy from its motion and allow it to spiral inward, closer to the sun. After seven such course changes, the probe will be in an 88-day elliptical orbit of the sun, with a closest approach of about 3.8 million miles.
In total, the spacecraft will complete 24 orbits, and the mission is to end in 2025.
During its later orbits, the strong pull of the sun’s gravity will accelerate the probe to 430,000 miles per hour, which will be the fastest human-made object ever.
The spacecraft is named for Eugene N. Parker, a retired University of Chicago astrophysicist who was the first to predict the solar wind. It is the first time NASA has named a mission for a living person.
Dr. Parker, 91, who took in the launch from Florida on Sunday, expressed his enthusiasm about the scientific potential of the mission.
“All I can say is wow, here we go,” he said on a NASA broadcast after the liftoff. “We’re in for some learning over the next several years.”
Michael Roston contributed reporting.