After coming within a record 15 million miles (24 million km) of the Sun's surface on November 5, 2018, NASA's Parker Solar Probe has completed its first orbit and is heading back for another fiery close encounter. On January 19, the unmanned spacecraft reached aphelion, or its farthest distance from the Sun, and is now being readied by mission control for its second solar plunge on April 4.

The specially constructed Parker Solar Probe is in an eccentric orbit that is growing tighter and tighter with each revolution, while it makes a total of 24 close encounters with the Sun. On its first encounter, it came within half the distance of the previous closest approach by the German-American Helios 2 mission in 1976. As it spirals in, it will eventually skim through the upper reaches of the solar atmosphere, or corona.

Because it will be encountering unprecedented high temperatures and radiation, the Parker Solar Probe requires careful preparation for each perihelion, or close approach. According to NASA, the craft went into full operational status on January 1 and is transmitting data via the space agency's Deep Space Network (DSN).

So far, 17 gigabits of information have been received by mission control and the balance from the first orbit is expected by April before its solid-state memory is wiped of transmitted files to make room for the next batch. In addition, the onboard computer is getting updates to its programming, such as positioning and navigation datasets, along with a new automated command sequence that will allow it to operate autonomously for a month.

When the Parker Solar Probe makes its next close encounter it will, again, come within 15 million miles of the Sun. As it passes, the four onboard instrument suites will collect data, such as the acceleration of the solar winds, as well as learning more about the corona. As it does so, the temperature on the sunward side of the craft's heat shield will reach about 820° F (438° C).

"It's been an illuminating and fascinating first orbit," says Parker Solar Probe Project Manager Andy Driesman, of the Johns Hopkins University Applied Physics Laboratory, which designed, built and manages the probe. "We've learned a lot about how the spacecraft operates and reacts to the solar environment, and I'm proud to say the team's projections have been very accurate."

Source: NASA

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