Why NASA Wants to 'Touch the Sun'

NASA's Parker Solar Probe, as seen in this illustration, will eventually fy to within 4 million miles of the sun's surface. (Photo: NASA, Steve Gribben)

The sun, the very centerpiece of our solar system and the most important source of energy for life on Earth, has a visitor.

NASA's Parker Solar Probe has been studying the sun, flying closer than ever before, and making incredible new discoveries with each new visit. The latest visit, which NASA scientists have described in several papers just published in the journal Nature, has revealed never-before-seen characteristics of the solar wind at its birthplace, information that can help us understand why solar winds can be so turbulent and, at times, destructive to modern life on Earth.

"This first data from Parker reveals our star, the Sun, in new and surprising ways," Thomas Zurbuchen, associate administrator for science at NASA Headquarters in Washington, said in a NASA release. "Observing the Sun up close rather than from a much greater distance is giving us an unprecedented view into important solar phenomena and how they affect us on Earth, and gives us new insights relevant to the understanding of active stars across galaxies. It’s just the beginning of an incredibly exciting time for heliophysics with Parker at the vanguard of new discoveries."

The probe measured a portion of the solar wind coming from a small hole in the sun’s corona near the equator and also found that as the solar wind streams out, sections of it burst out in high-velocity spikes or "rogue waves," as Justin Kasper, a space scientist at the University of Michigan in Ann Arbor described them. You can learn more about the new discoveries in the video below.

Why this mission is a big deal

The probe achieved a milestone in October 2018 by becoming the closest man-made object to the sun. The previous record was held by the German-U.S. Helios 2 satellite, which was 26.55 million miles from the sun. Over the next several years, the probe will orbit closer to the sun with the closest approach being 3.83 million miles away.

In November of that year, the probe completed its first solar encounter phase through the sun's outer atmosphere, the corona. And in September 2019, the probe completed its third close approach of the sun, called perihelion. At the time of perihelion, the spacecraft was about 15 million miles from the sun’s surface, traveling at more than 213,200 miles per hour. That most recent visit, combined with what the Parker team learned from previous missions, spurred the publication of the new papers.

"Parker Solar Probe is providing us with the measurements essential to understanding solar phenomena that have been puzzling us for decades," said Nour Raouafi, Parker Solar Probe project scientist at the Johns Hopkins University Applied Physics Lab. "To close the link, local sampling of the solar corona and the young solar wind is needed and Parker Solar Probe is doing just that."

NASA mission to the sun launch
At Cape Canaveral, the Delta IV Heavy rocket with NASA’s Parker Solar Probe lifts off at 3:31 a.m. EDT on Aug. 12, 2018. (Photo: NASA/Kim Shiflett)

The probe is named after astrophysicist Eugene Parker, the S. Chandrasekhar Distinguished Service Professor Emeritus in the Department of Astronomy and Astrophysics at the University of Chicago, who discovered the phenomenon now known as solar wind.

"Parker Solar Probe has been one of our most challenging missions to date," said Omar Baez, NASA launch director, after the August 2018 launch. "I'm very proud of the team that worked to make this happen. We at NASA and the Launch Services Program are thrilled to be part of this mission."

"The solar probe is going to a region of space that has never been explored before," Parker said in an earlier statement. "It’s very exciting that we’ll finally get a look. One would like to have some more detailed measurements of what’s going on in the solar wind. I’m sure that there will be some surprises. There always are."

This is the first time NASA has named a mission after a living individual, a testament to Parker's vast body of work.

"Placed in orbit within 4 million miles of the sun’s surface, and facing heat and radiation unlike any spacecraft in history, the spacecraft will explore the sun’s outer atmosphere and make critical observations that will answer decades-old questions about the physics of how stars work," NASA said in a 2017 statement. "The resulting data will improve forecasts of major space weather events that impact life on Earth, as well as satellites and astronauts in space."

As the Solar Probe Plus makes its closest approach to the sun, it will experience temperatures outside its heat shield of nearly 2,500 degrees Fahrenheit.
As the Parker Solar Probe makes its approach to the sun, it will experience temperatures outside its heat shield of nearly 2,500 degrees Fahrenheit. (Photo: NASA/Steve Gribben)

Unlike the Greek legend Icarus, whose wings melted when he flew too close to the sun, NASA's new spacecraft came prepared. To protect its instruments from temperatures approaching 2,600 degrees Fahrenheit (1,426 degrees Celsius), the Parker Solar Probe (which was originally named the Solar Probe Plus) features an 8-foot-wide, 4.5-inch-thick carbon-composite foam shield called the Thermal Protection System (TPS).

Unlike traditional armor, TPS weighs only 160 pounds and has an internal structure of 97 percent air. The engineering behind its design is so efficient that those components protected on the shaded side will astoundingly experience nothing more than room temperature. NASA installed the shield in June after it was briefly attached late last year just for testing.

Much like the Cassini spacecraft's series of ever-closer dives toward Saturn, the probe will experience no fewer than 24 close encounters with the sun using repeated gravity assists from Venus. The next encounter is expected in January 2020. Its most precarious dive through the sun's outer atmosphere, projected to occur in 2024, will have it passing by the sun's surface at a distance of only 3.8 million miles. As a comparison, the closest NASA has ever approached the sun is from a distance of 27 million miles with the Helios 2 spacecraft in 1976.

At that point, the Parker Solar Probe will make history by becoming the fastest man-made object ever. Its closest approach to the sun will send the spacecraft speeding along at a record-breaking 450,000 miles per hour. "That's fast enough to get from Philadelphia to Washington, D.C., in one second," NASA added.

Exposing the sun's secrets

The Solar Probe Plus, seen here in April 2017, is being constructed in the cleanroom at the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland.
The then-named Solar Probe Plus, seen here in April 2017, is constructed in the cleanroom at the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland. (Photo: NASA)

In addition to sending a spacecraft into uncharted, scorching territory above a star, NASA also has a series of scientific objectives to accomplish. These include a study of the causes behind the sun's wildly different temperatures (i.e., an atmospheric temperature range of 3.5 million F vs. a surface temperature of "only" 10,000 degrees F) and the forces behind its solar wind and energetic particles that impact Earth and the solar system.

"There are a few major mysteries with the sun and the solar wind," SPP project scientist Nicola Fox told Vice. "One is that the corona — the atmosphere that you see around the Sun during a solar eclipse — is actually hotter than the surface of the sun. So, that kind of defies the laws of physics. It just shouldn't happen."

NASA researchers hope the data gained from this mission will not only enable a greater understanding of how stars like our sun work, but also provide answers that might better protect against potentially catastrophic solar storms.

"Many of the systems we in the modern world rely on — our telecommunications, GPS, satellites and power grids — could be disrupted for an extended period of time if a large solar storm were to happen today," Justin C. Kasper, principal investigator at the Smithsonian Astrophysical Observatory, told Popular Mechanics. "Solar Probe Plus will help us predict and manage the impact of space weather on society."