Parker Solar Probe turned on its intstruments for its fifth solar flyby farther from the Sun than during previous encounters. Credit: NASA/Johns Hopkins APL/Steve Gribben

On May 9, 2020, NASA’s Parker Solar Probe began its longest observation campaign to date. The spacecraft, which has already completed four progressively closer orbits around the Sun, activated its instruments at a distance of 62.5 million miles from the Sun’s surface, some 39 million miles farther from the Sun than a typical solar encounter. The four instrument suites will continue to collect data through June 28, markedly longer than the mission’s standard 11-day encounters.

The nearly two-month campaign is spurred by Parker Solar Probe’s earlier observations, which revealed significant rotation of the solar wind and solar wind phenomena occurring much farther from the Sun than previously thought. The earlier activation of the science instruments allows the team to cover a larger range in order to trace the evolution of the solar wind as it moves away from the Sun.

“We have a real opportunity here to see what’s going on in these regions further from the Sun’s corona,” said Nour Raouafi, Parker Solar Probe project scientist at the Johns Hopkins Applied Physics Laboratory. “While our primary goal is to understand the mysteries at the Sun’s corona and the ‘young’ solar wind closer to the Sun, there is evidence indicating very interesting physics to explore earlier in the orbit and link that to what occurs near the Sun. We have the capability to gather this data and see what it yields.”

The spacecraft will reach its closest point to the Sun for this orbit, called perihelion, on June 7. At perihelion, Parker Solar Probe will be about 11.6 million miles from the Sun’s surface, matching its own record for closest human-made object to the Sun set during its fourth orbit on Jan. 29.

After this solar encounter, the spacecraft will swoop by Venus for its first outbound flyby of the planet. This is when Parker Solar Probe will perform its third Venus gravity assist, which will allow the spacecraft to shed some of its orbital energy and get much closer to the Sun on the following orbit. Flying at an altitude of approximately 516 miles above Venus’ surface — much lower than the previous two flybys but still well above Venus’ atmosphere — Parker Solar Probe will also witness a brief 11-minute solar eclipse during the maneuver. All four instrument suites will be on and collecting data about the near-Venus environment and the planet’s night side during the flyby.

Data from this fifth observation campaign will be downlinked to Earth between late June and mid-August 2020, and will be released to the public in November 2020.

By Justyna Surowiec
Johns Hopkins University Applied Physics Lab