Delta IV launch tonight will boost NASA's $1.5 billion solar probe from Cape Canaveral

Update: Saturday morning's launch was scrubbed due to technical issues. Teams will set up for a 24-hour recycle, so the next attempt will be at 3:31 a.m. Sunday morning. Follow live here.

Only 4.5 inches of carbon composite shielding will stand guard between a $1.5 billion NASA mission and the ferocity of Earth's solar neighbor.

As Parker Solar Probe hurtles past the sun at hundreds of thousands of miles per hour during several flybys, its four instrument suites will lean on the spacecraft's Thermal Protection System for support as it keeps temperatures of up to 2,500 degrees at bay. Behind the 8-foot-wide shield of superheated carbon-carbon composite, meanwhile, the spacecraft's interior is expected to remain a toasty 85 degrees.

That's a far cry from what Parker Solar Probe will see Saturday: Air Force weather forecasters are expecting 70 percent "go" conditions for a United Launch Alliance Delta IV Heavy rocket to boost the 1,400-pound spacecraft at 3:33 a.m., the opening of a 65-minute launch window at Cape Canaveral Air Force Station's Launch Complex 37. The mission will mark the only Delta IV Heavy launch of the year for the Space Coast.

The protection system, according to heat shield lead engineer Betsy Congdon of Johns Hopkins University's Applied Physics Laboratory, which built the spacecraft, is "perfectly designed to cover what it needs to cover."

[NASA Administrator Bridenstine gets one-of-a-kind tour of KSC] 

"Every surface on that shield is designed to either protect or enable something below," she said during a pre-launch news briefing at Kennedy Space Center in July.

If all goes according to plan, the instruments behind the heat shield will help scientists understand behaviors of the sun that are still largely mysterious, such as why the corona, or outer atmosphere, is multitudes hotter than its surface. Gathering more on solar wind speeds and eruptions, meanwhile, is also expected to help better understand how those activities impact astronauts, spacecraft and Earth-based infrastructure. It could have implications for studying climate change, too.

"The sun is full of mysteries," Parker Solar Probe Project Scientist Nicola Fox said during a pre-launch briefing at KSC Thursday. "We've looked at it, we've studied it from missions that are even as close as the planet Mercury, but we have to go there."

Seven years of observations will be made possible by Venus, which will host seven Parker Solar Probe gravity assist maneuvers to guide the 10-foot-tall spacecraft closer and closer to the sun. Its closest approach – of 24 total – will bring it within 3.8 million miles at a whopping 430,000 mph, enabling the probe to break two records: the fastest human-made object in history as well as the closest to the sun.

"If I put the sun and the Earth in the end zones on a football field, Parker Solar Probe will be on the four-yard line in the red zone knocking on the door for a touchdown," Fox said, which will cover 95 percent of the gap between Earth and the sun.

Getting to Venus, though, means the relatively lightweight spacecraft needs an extra push to break the Earth's gravitational influence – that's where Delta IV Heavy's first ever third stage comes into play, which will fire about 37 minutes after liftoff and separate from the probe six minutes later.

Parker Solar Probe is decades in the making: In 1958, University of Chicago astrophysicist Eugene Parker published "Dynamics of the Interplanetary Gas and Magnetic Fields," an article that predicted the existence of high-speed matter and magnetism escaping the sun, also known as solar wind.

"We've had to wait so long for our technology to catch up with our dreams," Fox said of the spacecraft, which has also been described as the most autonomous ever built. The heat shield alone, for example, was under development for 10 years and took 18 months to build.

On Saturday, 60 years after the publication of his article, the 91-year-old Parker will watch from KSC as the 233-foot-tall, three-core rocket takes off with the spacecraft named after his accomplishments. It's the first time NASA has named a mission for a living individual.

"I was stunned and didn't know what to say," Parker said at KSC Thursday while recalling the first conversation with NASA during which teams asked for permission to use his name. "So I said yes."

"I have always said on a mission like this into new territory, you're always going to be in for some new surprises," he said during the briefing, noting that this will be his first in-person launch. "Your point of view will have to change to conform with the data. That’s the fun part.”

All scientific missions for NASA are ambitious, Fox said, but Parker's takes technology, speed and physics to new heights.

"Certainly to send a probe where you haven't been before is ambitious," she said. "To send it into such brutal conditions is highly ambitious."

Contact Emre Kelly at aekelly@floridatoday.com or 321-242-3715. Follow him on Twitter and Facebook at @EmreKelly.

Launch Saturday

• Rocket: United Launch Alliance Delta IV Heavy
• Mission: NASA's Parker Solar Probe
• Launch Time: 3:33 a.m.
• Window: To 4:38 a.m.
• Launch Complex: 37 at Cape Canaveral Air Force Station
• Weather: 70 percent "go"

Join floridatoday.com/space for countdown updates and chat at 2:30 a.m. Saturday, including streaming of NASA's launch webcast starting 30 minutes before liftoff.

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