NASA rescheduled the launch of Parker Solar Probe on August 6. A United Launch Alliance Delta IV Heavy will light up the sky near Cape Canaveral, Florida.

On late Wednesday NASA announced the two-day delay from the previous target launch date of Aug. 4.

“Additional time was needed to evaluate the configuration of a cable clamp on the payload fairing,” NASA said. “Teams have modified the configuration and encapsulation operations have continued.”

NASA said technicians at the Astrotech processing facility have repaired a leak discovered last week in purge ground support tubing on the Star 48 rocket motor.

However, the space agency has planned the Liftoff for approximately 4:08 a.m. EDT (0808 GMT) Aug. 6.

“The spacecraft is buttoned up, looking beautiful and ready for flight,” Nicola Fox, Parker Solar Probe project scientist at Johns Hopkins Applied Physics Laboratory, said during a NASA press conference Friday.

This is NASA’s first mission to the sun and its outermost atmosphere called the corona.

The Parker Solar Probe will explore the sun’s atmosphere wearing a nearly 5-inch coat of carbon-composite solar shields.

“We’ve been studying the Sun for decades, and now we’re finally going to go where the action is,” said Alex Young, associate director for science in the Heliophysics Science Division at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

Parker Solar Probe will depart Earth on a trajectory to fly by Venus in September. It will be the first of seven gravity assist maneuvers to move the spacecraft’s orbit closer to the sun.

So, after each flyby of Venus, the probe will get closer to the Sun. Therefore, reaching the closest point to the sun, at a distance of around 3.8 million miles (about 6.2 million kilometers) in late 2024. That’s well inside the orbit of Mercury.

The Survey

The spacecraft carries a swarm of instruments to study the Sun. The collected data from these instruments could boost our knowledge on the physics of stars, change what we know about the mysterious corona, increase understanding of solar wind and help improve forecasting of major space weather events. Those events can impact satellites and astronauts as well as the Earth — including the power grid and radiation exposure on airline flights, NASA said.

The mission’s objectives include “tracing the flow of energy that heats and accelerates the sun’s corona and solar wind, determining the structure and dynamics of the plasma and magnetic fields at the sources of the solar wind and explore mechanisms that accelerate and transport energetic particles.”

To achieve this, Parker Solar Probe uses four suites of instruments.

First, the FIELDS suite, whom the University of California, Berkeley, controls. The instrument measures the electric and magnetic fields around the spacecraft. It also captures waves and turbulence in the inner heliosphere with high time resolution. Thus, understanding the fields associated with waves, shocks and magnetic reconnection, a process by which magnetic field lines explosively realign.

Second, the WISPR (Wide-Field Imager for Parker Solar Probe) instrument. This is the only imaging instrument aboard the spacecraft. WISPR captures structures like coronal mass ejections, or CMEs, jets and other ejecta from the Sun. Therefore, helping link what’s happening in the large-scale coronal structure to the detailed physical measurements captured directly in the near-Sun environment. WISPR is led by the Naval Research Laboratory in Washington, D.C.

Then, the SWEAP suite, short for Solar Wind Electrons Alphas and Protons Investigation, uses two complementary instruments to gather data. The suite counts the most abundant particles in the solar wind—electrons, protons, and helium ions. It also measures such properties as velocity, density, and temperature. Therefore, improving our understanding of the solar wind and coronal plasma. The University of Michigan, the University of California, Berkeley, and the Smithsonian Astrophysical Observatory in Cambridge, Massachusetts, lead the SWEAP suite.

Finally, the IS?IS suite—short for Integrated Science Investigation of the Sun, and including ?, the symbol for the Sun, in its acronym—measures particles across a wide range of energies. Therefore, understanding where they came from, how they became accelerated and how they move out from the Sun through interplanetary space. IS?IS is led by Princeton University in New Jersey.

Thumbnail image: Illustration of NASA’s Parker Solar Probe leaving Earth. Credit: NASA/Johns Hopkins APL/Steve Gribben.