NASA has said that its Parker Solar Probe that will be the first spacecraft to be closest to the Sun is almost ready for launch and that it could be launched as early as August second week aboard a United Launch Alliance Delta IV Heavy.
Parker Solar Probe is one of the most advanced satellites that will study our Sun. The spacecraft carries a lineup of instruments to study the Sun both remotely and in situ, or directly. Together, the data from these state-of-the-art instruments should help scientists answer three foundational questions about our star.
One of those questions is the mystery of the acceleration of the solar wind, the Sun’s constant outflow of material. Though we largely grasp the solar wind’s origins on the Sun, we know there is a point – as-yet unobserved – where the solar wind is accelerated to supersonic speeds. Data shows these changes happen in the corona, a region of the Sun’s atmosphere that Parker Solar Probe will fly directly through, and scientists plan to use Parker Solar Probe’s remote and in situ measurements to shed light on how this happens.
Second, scientists hope to learn the secret of the corona’s enormously high temperatures. The visible surface of the Sun is about 10,000 F – but, for reasons we don’t fully understand, the corona is hundreds of times hotter, spiking up to several million degrees F. This is counterintuitive, as the Sun’s energy is produced at its core.
Finally, Parker Solar Probe’s instruments should reveal the mechanisms at work behind the acceleration of solar energetic particles, which can reach speeds more than half as fast as the speed of light as they rocket away from the Sun. Such particles can interfere with satellite electronics, especially for satellites outside of Earth’s magnetic field.
To answer these questions, Parker Solar Probe uses four suites of instruments.
The FIELDS suite, led by the University of California, Berkeley, measures the electric and magnetic fields around the spacecraft. FIELDS captures waves and turbulence in the inner heliosphere with high time resolution to understand the fields associated with waves, shocks and magnetic reconnection, a process by which magnetic field lines explosively realign.
The WISPR instrument, short for Wide-Field Imager for Parker Solar Probe, is the only imaging instrument aboard the spacecraft. WISPR takes images from of structures like coronal mass ejections, or CMEs, jets and other ejecta from the Sun to help link what’s happening in the large-scale coronal structure to the detailed physical measurements being captured directly in the near-Sun environment. WISPR is led by the Naval Research Laboratory in Washington, D.C.
Another suite, called SWEAP (short for Solar Wind Electrons Alphas and Protons Investigation), uses two complementary instruments to gather data. The SWEAP suite of instruments counts the most abundant particles in the solar wind — electrons, protons and helium ions — and measures such properties as velocity, density, and temperature to improve our understanding of the solar wind and coronal plasma. SWEAP is led by the University of Michigan, the University of California, Berkeley, and the Smithsonian Astrophysical Observatory in Cambridge, Massachusetts.
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. By measuring electrons, protons and ions, IS?IS will understand the particles’ lifecycles — 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.
Parker Solar Probe is a mission some sixty years in the making. With the dawn of the Space Age, humanity was introduced to the full dimension of the Sun’s powerful influence over the solar system. In 1958, physicist Eugene Parker published a groundbreaking scientific paper theorizing the existence of the solar wind. The mission is now named after him, and it’s the first NASA mission to be named after a living person.