Parker Solar Probe Cleared For Launch to the Sun Saturday at 3:33am EDT

NASA’s Parker Solar Probe mission and launch teams today concluded a successful Launch Readiness Review, finding no technical issues at this time, giving a GO for liftoff on Saturday, Aug. 11, at 3:33 a.m. EDT on a United Launch Alliance Delta IV Heavy rocket from Cape Canaveral. Photo Credit: NASA

Mission and launch teams for NASA’s Parker Solar Probe gave the GO for flight Saturday morning (Aug 11), after concluding a successful Launch Readiness Review today and finding no technical issues. Liftoff of the $1.5 billion mission, the first ever to ‘touch’ the sun, is scheduled for liftoff at 3:33 a.m. EDT atop a 232-foot tall United Launch Alliance (ULA) Delta IV Heavy rocket from Cape Canaveral Air Force Station Launch Complex-37B, at the opening of a 65-minute launch window. The weather forecast currently calls for a 70% chance of favorable conditions for launch.

Built by the Johns Hopkins Applied Physics Laboratory in Laurel, Maryland, the lightweight car-sized PSP is the most autonomous spacecraft ever made, and will become the fastest human-made object in history when it makes its closest approach to the sun, traveling at speeds of up to 430,000 miles per hour (700,000 kilometers per hour) as it swoops through the sun’s atmosphere 24 times over a period of 7 years, or as fast as traveling from New York City to Tokyo in less than one minute.


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The spacecraft was encapsulated within its 62.7-foot bullet-like payload fairing in mid July, and was transported from its clean room processing facility to the launch pad on the night of July 30-31. The move took 7 hours to complete, before arriving to meet its rocket early in the morning July 31. Workers then carefully hoisted the spacecraft over 230 feet high and integrated it atop the impressive triple-barreled launcher.

Encapsulated in its payload fairing, NASA’s Parker Solar Probe is mated to a United Launch Alliance Delta IV Heavy rocket at Cape Canaveral Air Force Station’s Space Launch Complex 37 on Tuesday, July 31, 2018. Photo Credit: NASA

But PSP only has until August 23 to launch, otherwise it will miss the planet Venus, whose gravity the spacecraft will need to “steer” itself into the proper orbits of the sun for the mission’s science objectives, getting closer and closer with each orbit. The next window of opportunity isn’t until May 2019, when Venus is in position again to give PSP the gravity-assists it needs to reach the brutally hostile corona and sample the sun’s atmosphere.

It’s a small spacecraft in one of the most powerful rockets in the world, because it requires such an extremely high energy launch; 55 times more energy than reaching Mars actually. Even the Delta-IV Heavy can’t do that alone, so the spacecraft will employ a third rocket stage, a Star 48BV from Northrop Grumman, to gain the incredible speed it needs to reach the sun.

Scientists have been trying to answer some of the big questions about the Sun for over 60 years, such as how does energy and heat move through the solar corona? What accelerates the solar wind and solar energetic particles? And why is the temperature of the Sun’s surface about 10,000 degrees Fahrenheit, while its corona, or “atmosphere”, can reach millions of degrees Fahrenheit?

  • Read our story on the science of the mission HERE.

But to get the answers, you have to actually go there, and fly through the corona itself.

Illustration of the orbit of PSP around the Sun. PSP will swoop through the Sun’s “atmosphere” (corona) 24 times over a period of 7 years. Image Credit: NASA’s Scientific Visualization Studio

Upon liftoff the rocket will head due East, pushing over 2 million pounds of thrust from its three liquid hydrogen and liquid oxygen-burning RS-68A engines. Once the two outer cores are spent at 3:57 into flight they will jettison, and the center core will go on until its engine is spent at 5:35. Eight seconds later the first stage will separate, followed seconds later by ignition of the rocket’s 24,750 lb-thrust second stage cryogenic liquid hydrogen/liquid oxygen RL10B-2 engine.

Ten seconds later the fairings will jettison, exposing PSP to space for the first time as the second stage engine continues accelerating it ahead until 10:37, coasting for several minutes until reigniting at 22:25 and cruising over Africa and Madagascar until the seined engine cutoff at 36:38.

The second stage will then separate, and the third stage engine will ignite to take over at 37:29, burning for about 1.5 minutes and burning out, then deploying the spacecraft off the coast of Australia at 43:18, sending it on its way to becoming the fastest spacecraft in history as it comes face to face with our star to sample its corona.

  • Follow our coverage from Cape Canaveral and Kennedy Space Center with our launch tracker.

Image: ULA


PSP will reach its first close encounter with the Sun in November, after looping around Venus and using its gravity to slow down. On its first approach, it will reach a distance from the center of the Sun equal to 36 times the Sun’s radius (36 solar radii). By comparison, Venus orbits at 155 solar radii and Mercury at 83 solar radii. Eventually, over the next 6 years, PSP will come to within 9.8 solar radii.

“The goal of the mission is to get inside that transition region, so we get into the real corona where the flow is subAlfvénic,” said Stuart Bale,a UC Berkeley professor of physics, former director of the campus’s Space Sciences Laboratory and one of four principal investigators for the instruments aboard the mission. “We think that boundary is at about 15 solar radii, so we probably won’t start hitting it until 2021.”

“In early December, I am counting on having that first pass of data at 35 solar radii, and I am sure it will be revolutionary. There will be great new stuff in there, from what we know about previous missions,” he added.

Illustration of the orbit of PSP around the Sun. PSP will swoop through the Sun’s “atmosphere” (corona) 24 times over a period of 7 years. Image Credit: NASA’s Scientific Visualization Studio

Space weather plays a vital role in the health of not only our home planet, but the entire solar system overall. The more we know about how the sun works, the more we can understand and predict how it affects our celestial neighborhood and life here. We’ve been lucky so far, but it’s probably just a matter of time before a Coronal Mass Ejection cripples our satellites and power grids, and if we can have advanced warning that it will occur, it could save us all a lot of trouble. Not to mention, it could open our eyes as to how life on Earth developed and evolved, and teach us a lot about how stars across the universe behave.

  • Stay tuned for our coverage leading top to and following launch.

– Written by Mike Killian & Paul Scott Anderson


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