Touted as the “mission to touch the Sun,” the Parker Solar Probe will carry a suite of instruments closer to the nearest star than ever before in an effort to unlock its secrets. The Parker Solar Probe is also the first mission named after a living person, solar physicist Eugene Parker.
“Today’s launch was the culmination of six decades of scientific study and millions of hours of effort,” says project manager Andy Driesman (Johns Hopkins University). “Now, Parker Solar Probe is operating normally and on its way to begin a seven-year mission of extreme science.”
The Science of the Sun
The Parker Solar Probe will soon be speeding toward the Sun at 430,000 mph (192 km/s) — breaking the previous record held by the Helios-B spacecraft and making it the fastest spacecraft to date. Its primary mission is to dip down into the lower solar corona, a region where several key — and still poorly understood — space weather processes occur. The probe will send back data to help scientists understand the origin and acceleration of the solar wind and the dynamics of the coronal magnetic field.
To accomplish this, the Parker Solar Probe will first fly by Venus in October to slow it down, putting it on an initial elongated, 150-day orbit. The Parker Solar Probe will reach its first perihelion on November 1st of this year, which will already take it to within 35 times the radius of the Sun. But the goal is to come even closer.
Six additional Venus flybys will decrease its orbit to 88 days, which will take it from an aphelion of 0.73 a.u. (73% of the Earth-Sun distance or 67.9 million miles), down to a perihelion of just 8.9 solar radii (0.04 a.u. or 3.9 million miles) from the Sun's surface. Those maneuvers will put the probe well within Mercury's orbit (its perihelion is 0.3 a.u.) and closer to the Sun than any other spacecraft has ever been.The probe will complete 24 orbits around the Sun in its seven-year mission.
Parker Solar Probe orbit diagram
Parker Solar Probe will use seven Venus flybys over nearly seven years to gradually shrink its orbit around the sun, coming within 9 times the solar radius — that's about seven times closer than any spacecraft has come before. (The numbers here are calculated from the Sun's center rather than its surface.)
NASA / JPL
The probe will be the first mission to go past what's known as the Alfvén point. Within this boundary, complex, fast-moving Alfvén waves — oscillations in the magnetic field and the movement of charged particles — travel back and forth to the Sun, connecting charged particles to the Sun's surface. Beyond this boundary, thought to be the origin of the solar wind, Alfvén waves can no longer travel back to the solar surface and the particles escape out into the solar system.
Scientists also hope to use data from the Parker Solar Probe to solve the mystery of the super-hot corona, which blazes at millions of degrees, thousands of times hotter than the Sun's visible surface.
The Parker Solar Probe was developed from the Solar Orbiter concept of the early 1990s and will complement other Sun-observing missions, such as NASA's Solar Dynamics Observatory and the aging Solar Heliospheric Observatory.
The Parker Solar Probe is venturing into hostile territory in the name of science and solar astronomy. Near its closest approach to the Sun, the solar wind will be so intense that the spacecraft's reaction wheels will have to push back constantly so the spacecraft doesn't flip. And it'll be hot, in the range of 2,500°F. To take the heat, the Parker Solar Probe is equipped with a heat shield made of 4.5-inch (11.4 centimeter) thick reinforced carbon composite.
On the protected side of the shield, temperatures will be a comfortable 85°F. But a couple instruments — including the Solar Probe Cup (SPC) — will brave the heat to look directly at the Sun. The SPC will extend beyond the heat shield to scoop up samples of charged particles in order to measure their flux and flow.
The major instrument suites aboard the Parker Solar probe a variety of properties of the Sun's outer atmosphere and the solar wind.
ISIS (Integrated Science Investigation of the Sun) has two instruments (EPI-Hi and EPI-Lo) to measure energetic heavy ions, protons, and electrons in the Sun's atmosphere, correlating them with solar wind and coronal structures. The instrument suite is run by Princeton University.
FIELDS (Electromagnetic Fields Investigation). Four of FIELDS' five niobium-alloy antennas will extend beyond the heat shield to measure the electric and magnetic fields around the Sun with the help of three magnetometers. Run by the University of California, Berkeley, this project will measure waves, turbulence, radio emissions, and shock waves in the fast and slow solar winds.
SWEAP (Solar Wind Electrons, Alphas and Protons) uses two instruments, the Solar Probe Cup and Solar Probe Analyzers, to measure the coronal and solar wind plasma. The instruments were developed by the Smithsonian Astrophysical Observatory and the University of Michigan.
WISPR (The Wide-field Imager for Solar Probe). The primary optical imagers for the mission, designed and operated by the Naval Research Laboratory, will help analyze the inner heliosphere and the solar corona. This instrument will generate most of the eye-candy images.
The Parker Solar Probe will also perform key simultaneous observations of the solar corona during upcoming total solar eclipses. Scientists are still analyzing data gathered from last August's total solar eclipse across the United States. With a primary mission of 6 years, 321 days, the Parker Solar Probe will be ready for business for the next total solar eclipse crossing South America on July 2, 2019, and may even be on station for the next eclipse across the United States on April 8, 2024.
“This mission truly marks humanity’s first visit to a star that will have implications not just here on Earth, but how we better understand our universe,” says Thomas Zurbuchen (NASA). “We’ve accomplished something that decades ago, lived solely in the realm of science fiction.”
It will be exciting to see the Parker Solar Probe mission get underway, opening up a new window on solar physics and unlocking the secrets of our tempestuous host star.