NASA's record-breaking solar mission silently completed another close pass of the sun yesterday (April 4).
The maneuver, called a perihelion, resulted in a closest approach at 6:40 p.m. EDT (2240 GMT) yesterday, when the Parker Solar Probe was about 15 million miles (24 million kilometers) above the surface of the sun. That's about the same distance as the spacecraft reached on Nov. 5, 2018, during its first perihelion.
Both of the close grazes broke the previous record, set by the Helios 2 mission in 1976, for the closest a spacecraft has ever come to the sun. But the Parker probe will continue to break its own records during the mission, eventually skimming just 4 million miles (6 million km) above the star's surface.
A similar process is playing out with the probe's speed: At the peak of its first two perihelions, the spacecraft traveled at about 213,200 mph (343,000 km/h), also breaking records, but future close approaches will see the Parker Solar Probe moving still faster.
These close grazes are anxious times for scientists and engineers on the mission because the spacecraft is out of communication with Earth for several days before and after each perihelion. The radio silence is designed to let the spacecraft focus on keeping its instruments tucked safely behind the thick shield that protects them from the incredible heat of the sun's outer atmosphere, the corona.
After the spacecraft retreats from the sun again in its orbit, the data gathered during the maneuver is sent back to scientists eagerly awaiting the information. The researchers hope to use that data to better understand the corona, where temperatures reach millions of degrees in Fahrenheit and Celsius alike.
The corona is also the source of the solar wind, a constant flow of charged particles that stream off of the sun and across the solar system. Because the solar wind can interfere with communication and navigation satellites in orbit around Earth, scientists hope to use the Parker Solar Probe data to better understand how the solar wind works, at its source.
The spacecraft will conduct another perihelion on Sept. 1 and then use Venus' gravity to adjust its path. The orbital tweak will mean the probe's subsequent close approaches will come just a bit closer to the sun's surface. All told, the spacecraft will complete 24 perihelions over the course of its seven-year mission, inching ever closer to the sun and its secrets.
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