Aug. 6 (UPI) -- NASA's Parker Solar Probe is expected to fly closer to the sun than any spacecraft in history.
Scientists expect the spacecraft's record trip, scheduled for Saturday, to offer profound insights into the nature of the sun's atmosphere, called the corona and its solar winds.
The sun's corona is full of mysteries.
"The Parker Solar Probe's observations will help us answer questions like: Why is the corona a couple million degrees hotter than the sun?" Eric Christian, a space scientist at NASA's Goddard Space Flight Center, told UPI.
Most of Earth's atmosphere gets colder at high elevations.
"Another question we hope to answer is: Why is the solar wind accelerating up to very high speeds in the corona?" Christian said. "Some high-energy solar particles accelerate to nearly half the speed of light, and we don't know why."
To help scientists answer these questions, engineers have outfitted the solar probe with a variety of instruments. The FIELDS instrument suite, a series of antennas and magnetometers, will measure shape and scale of the corona's electric and magnetic fields.
The Solar Probe Cup and Solar Probe Analyzers will measure electrons, protons and helium ions, the most abundant solar wind particles. The Energetic Particle Instrument -- actually a pair of instruments, EPI-Lo and EPI-Hi -- will also detect and measure electrons, protons and ions, but across a wider energy spectrum.
None of the instruments would be of much help, however, without the probe's next-generation heat shield.
"The thermal protection system is so important," Christian said. "We couldn't have a mission if that wasn't tested to death and perfected."
The sandwich-like layers of foam and carbon fiber, further insulated and strengthened with special coats of paint, create an incredible lightweight defense against the extreme temperatures the probe will encounter as it flies within 4 million miles of the sun's surface.
In addition to extreme temperatures, the Parker Solar Probe will face the risk of collision. The probe will become the fastest manmade object in history as it speeds toward the sun. At such extreme speeds, even a tiny speck of dust can do damage.
"The probe's carbon fiber shield compensates for those high-velocity impacts," Geronimo Villanueva said in a recent interview.
The probe is designed to study the sun's atmosphere at small scales, particle by particle. Scientists believe these miniature measurements will improve their understanding of solar phenomena, much the way small-scale surveys of Earth's atmosphere -- the study of clouds and the movement of atmospheric particles -- revolutionized weather prediction models during the latter half of the 20th century.
Likewise, scientists hope the probe's small-scale, short-term analysis will improve space weather prediction models.
"We see these big storms happening on the sun and then see them collide with Earth," said Geronimo Villanueva. "That connection between sun phenomena and space weather in our upper atmosphere -- how that energy arrives at our planet -- is still not well understood."
The probe will execute several highly elliptical heliocentric orbits. On its way to and from the sun's atmosphere, the probe's wide field camera will provide large-scale images of the sun.
"So we have the broader context with the camera, and at the same time we have the instrument suite's localized measurements," Geronimo Villanueva said.
All the measurements compiled by the probe can improve scientist's understand of not only our own sun, but of faraway suns, too. Improved solar models can help scientists study sun-like stars elsewhere in the cosmos.
"Solar wind and space weather affect habitability, so understanding the dynamics of faraway stars can help us predict which stars are most likely to host habitable planets," Christian said.