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Illuminating First Light Data from Parker Solar Probe

SWEAP (Solar Wind Electrons Alphas and Protons)


Just over a month into its mission, Parker Solar Probe has returned first-light data from each of its four instrument suites. These early observations – while not yet examples of the key science observations Parker Solar Probe will take closer to the Sun – show that each of the instruments is working well. The instruments work in tandem to measure the Sun's electric and magnetic fields, particles from the Sun and the solar wind, and capture images of the environment around the spacecraft.

"All instruments returned data that not only serves for calibration, but also captures glimpses of what we expect them to measure near the Sun to solve the mysteries of the solar atmosphere, the corona," said Nour Raouafi, Parker Solar Probe project scientist at the Johns Hopkins University Applied Physics Lab in Laurel, Maryland.

The mission's first close approach to the Sun will be in November 2018, but even now, the instruments are able to gather measurements of what’s happening in the solar wind closer to Earth. Let’s take a look at what they’ve seen so far.

The SWEAP suite includes three instruments: Two Solar Probe Analyzers measure electrons and ions in the solar wind, while the Solar Probe Cup sticks out from behind Parker Solar Probe’s heat shield to measure the solar wind directly as it streams off the Sun. After opening covers, turning on high voltages and running internal diagnostics, all three instruments caught glimpses of the solar wind itself.

Because of Parker Solar Probe’s position and orientation, the science team expected that Solar Probe Cup would mostly measure background noise at first, without picking up the solar wind. But just after the instrument was powered on, a sudden, intense gust of solar wind blew into the cup, visible in the data as the red streak. As the spacecraft approaches the Sun, such observations will be Solar Probe Cup’s bread and butter — and will hopefully reveal new information about the processes that heat and accelerate the solar wind.

The two Solar Probe Analyzers (SPAN) also caught early peeks of the solar wind. During commissioning, the team turned the spacecraft so that SPAN-A — one of the two SPAN instruments — was exposed to the solar wind directly. It captured about 20 minutes' worth of data (right), including measurements of solar wind ions (top) and electrons (bottom). While SPAN-A and its sister instrument, SPAN-B, will measure solar wind electrons throughout the mission, the spacecraft’s orientation now means that SPAN-A will likely go several more years before it captures such ion measurements again. This is because solar wind electrons can be measured from any direction, as their low mass and high temperature make their motion much more random, while the much heavier solar wind ions follow a relatively direct path out from the Sun.

"SWEAP's solar wind and corona plasma instrument performance has been very promising," said Justin Kasper, principal investigator of the SWEAP instrument suite at University of Michigan. "Our preliminary results just after turn-on suggest we have a set of highly sensitive instruments that will allow us to do amazing science close to the Sun."

The Solar Probe Cup (SPC) was built at the Smithsonian Astrophysical Observatory (SAO) in Cambridge, Mass. On the SWEAP Investigation, SAO partners with team members from University of California, Berkeley Space Sciences Laboratory, the NASA Marshall Space Flight Center, the University of Alabama Huntsville, NASA Goddard Space Flight Center, Los Alamos National Laboratory, and the Massachusetts Institute of Technology. SAO built the SPC (Instrument Scientist: Tony Case), leads the Science Operations Center (Head of Science Operations: Kelly Korreck), and manages the overall SWEAP program.

The full NASA blog post on the Parker Solar Probe’s first light images, including from its other instrument packages, can be found at