Aug. 10, 2018On Saturday, NASA’s Parker Solar Probe is scheduled to launch from Cape Canaveral, Fla. The space agency is touting it as a mission “to touch the sun.” Here is some background information about the Parker mission.
Why would anyone want to touch the sun?The spacecraft will eventually pass within 4 million miles of the sun’s surface. That may still sound like quite a ways, but it’s close enough to skim through the sun’s outer atmosphere. Four million miles is about one-tenth the distance between the sun and Mercury, the innermost planet of the solar system.
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.
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.
What is solar wind?A stream of charged particles — primarily protons and electrons — 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 generates the beautiful aurora borealis, also known as the Northern and Southern lights, that flicker at night in the polar regions.
Solar wind originates in the corona, but how it is generated is not fully understood. The surface of the sun is about 10,000 degrees Fahrenheit. The Parker Solar Probe is expected to fill in many of the blanks.
The Parker Solar Probe on July 30, encapsulated and making its way to Cape Canaveral.CreditKim Shiflett/NASAIt could 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, damaging transformers on the electrical grid, potentially requiring months to years to repair.
[Sign up to get reminders for space and astronomy events on your calendar.]
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.
When does the Parker Solar Probe launch?Launch is scheduled for 3:33 a.m. Eastern time on Saturday. There is a 65-minute window if there are weather or technical issues. If the launch is called off, there are additional opportunities through Aug. 23 before the planets are too far out of alignment.
How do I watch the launch?If you’re not down in Cape Canaveral, and you like to wake up very early or stay up very late, NASA TV will broadcast coverage of the launch on the web beginning at 3 a.m. Saturday.
How big is the spacecraft?The Parker Solar Probe is fairly small for a spacecraft, about the size of a car and weighing 1,500 pounds at launch.
The spacecraft needs to be accelerated to a high enough speed to break away from Earth’s gravity and enter orbit around the sun. Thus, it is launching on top of a Delta 4 rocket, one of the most powerful currently available.
How will the probe get to the sun?On 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.
How fast will it go?On the 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.
Who is Parker?Until last year, the spacecraft was known as Solar Probe Plus. NASA renamed it 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.
Kenneth Chang has been at The Times since 2000 writing about physics, geology, chemistry, and the planets. Before becoming a science writer, he was a graduate student whose research involved the control of chaos. @kchangnyt
