UC Berkeley researchers build part of solar probe launched by NASA

NASA/Johns Hopkins APL/Lee Hobson/Courtesy

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The Parker Solar Probe, or PSP, was launched into space Aug. 12. Two of its four instruments, FIELDS and SWEAP, were built by campus researchers.

The PSP will come closer than any other spacecraft has ever been to the sun by entering the sun’s corona, the outer layer of the sun’s atmosphere.

According to Stuart Bale, a campus physics professor and the principal investigator for FIELDS, the purpose of the PSP is to learn why the sun’s corona is much hotter than its surface.

“The photosphere (of the sun) is 6,000 degrees Celsius,” Bale said. “But the corona is a couple million degrees Celsius and so hot it escapes the sun’s gravity and becomes solar wind.”

The PSP project started when NASA announced in 2009 that anyone could submit a proposal to be a part of the project, Bale said. Davin Larson, the principal investigator for SWEAP and a UC Berkeley physicist, added that the different groups could apply for different “elements of science” for the PSP project, and his and Bale’s teams were selected to each develop a separate PSP instrument.

According to Bale, FIELDS has one magnetometer to measure currents from fluctuating magnetic fields and two magnetometers that generate their own magnetic fields to measure solar winds’ magnetic fields. In addition, voltage probes can extend into the corona’s plasma to detect electric field differences, Bale said.

Larson said SWEAP measures the actual particles of the corona with electrostatic analyzers. The analyzers can select out their specific type of particle — electron, proton or alpha particle — and take measurements such as average velocity, temperature and density of a large number of particles, Larson said.

“It has three electrostatic analyzers that accept particles in field of view and dim them down to measure particles one at a time, quickly measuring angles the particles come from and the energy they have.” Larson said.

Larson explained that there were multiple challenges in building the PSP. He added that the PSP cost $1.5 billion, so there were “no second chances” when building the probe. The probe also had to be tested to withstand intense vibration, a vacuum environment and much heat, Bale said.

The roughly 70-person project involving at least five institutions began with building a cheaper engineering model of the PSP to ensure the science and programming of the PSP worked, according to Bale. Afterward, a more expensive flight model of the probe was built and underwent rigorous testing before finally being launched into space, he added.

“Fundamentally, we’re trying to understand how the corona is heated and accelerated to become solar wind,” Bale said.

Yao Huang covers research and ideas. Contact him at [email protected] and follow him on Twitter at @Yhoneplus.