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Post by swamprat on Jul 19, 2018 13:11:51 GMT -6
Death-defying NASA mission will make humanity’s closest approach to the SunThe Parker Solar Probe will dive into the sizzling solar corona to explore its mysteries.
Alexandra Witze | July 18, 2018
The Parker Solar Probe will travel seven times closer to the Sun's surface than any previous spacecraft.Credit: JHUAPL
Step aside, Icarus: NASA has made a spacecraft that can fly through the Sun’s atmosphere without melting.
On 4 August, if all goes to plan, the US$1.5-billion Parker Solar Probe will lift off from a launch pad at Florida’s Cape Canaveral. Just three months later, it will whiz far closer to the Sun than any spacecraft has ever come, to take the first-ever direct measurements of the star's maelstrom of energy.
But that's just the beginning. Over the next 7 years, the craft will loop around the Sun 23 more times, passing nearer and nearer — ultimately flying about 6.2 million kilometres above the surface, well within the solar corona. That’s nearly seven times closer than the record mark set by the German Helios 2 spacecraft in 1976.
The Parker Solar Probe aims to answer some of the biggest outstanding questions about the Sun, such as how its corona is heated to millions of degrees while the surface beneath it stays relatively cool. The spacecraft will also visit the birthplace of the solar wind, a flood of energetic particles that streams outward into the Solar System at speeds of up to 800 kilometres a second. When the solar wind slams into Earth, it generates beautiful polar aurorae, but it can also disrupt satellite communications and navigation systems.
“We’re going to be right where all the interesting stuff happens,” says Nicola Fox, a solar physicist at the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Maryland, and the mission’s project scientist.
Data from the deep-diving probe should allow researchers to better understand the complex picture of how particles, magnetic fields and energy combine in the Sun. “This is going to be such a game-changer,” says Nicholeen Viall, a solar physicist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.
Surfing the solar wind Space physicists have dreamed of a mission that would fly through the solar corona, or at least travel inside the orbit of Mercury, the innermost planet, since 1958. That same year, Eugene Parker — the University of Chicago physicist for whom the probe is named — first proposed the existence of the solar wind.
After decades on the drawing board, the mission is finally approaching launch. Eight weeks after lift-off, it will fly past Venus, using the planet’s gravity to slow down and slip into a tighter orbit around the Sun. Five weeks after that, on 3 November, the probe will make its first close approach — at more than 24 million kilometres, or 35 times the solar radius, from its surface.
From there, the spacecraft will loop around the Sun, drawing gradually closer as it flies past Venus 6 more times. That trajectory will give the probe ample time to gather data, says Yanping Guo, an engineer at APL who designed the mission trajectory.
Somewhere between the first close approach (at 35 solar radii) and its final ones (within 10 solar radii) the probe will encounter the Alfvén surface, a boundary where the solar wind becomes supersonic. Inside the Alfvén surface, the Sun’s magnetic field dominates; outside, the solar wind is more detached and streams away on its own.
Getting warmer Crossing that boundary with a spacecraft will be similar, symbolically, to the moment when the Voyager 1 probe entered interstellar space in 2012, says Justin Kasper, a physicist at the University of Michigan in Ann Arbor who has studied the Alfvén transition. The moment will mark humanity’s passage to another realm in the Solar System. “I’m confident that something special will happen,” he says.
The boundary might be more complicated than previously thought. A recent analysis of images of the outer corona taken by the STEREO spacecraft in 2014 reveals that the Alfvén surface might be more of a broadly, poorly defined zone that contains complicated magnetic structures. That suggests that the Parker Solar Probe will have the chance to measure a new and previously unexpected border zone. “It’s far more wild and woolly than we would have expected,” says Craig DeForest, a solar physicist at the Southwest Research Institute in Boulder, Colorado. He led the team behind the analysis, which was published on 18 July in the Astrophysical Journal.
The Parker Solar Probe bristles with an array of instruments designed to sample the corona directly. Protecting them is a 2.4-metre-wide heat shield made of 11-centimetre-thick carbon foam sandwiched between layers of carbon composite. It can withstand temperatures of nearly 1,400 °C.
Solar panels power the spacecraft, but to keep them cool they have a water-tubing system similar to a car’s radiator. During the searing conditions of close approach, most of the solar panels will fold back to shelter in the heat shield’s shade.
Staring at the Sun Mission scientists hope that the Parker Solar Probe will kick off a new era of studying the Sun. In 2020, the European Space Agency plans to launch its Solar Orbiter spacecraft, which will study the Sun at higher latitudes and from a more distant point in space than the Parker Solar Probe will. Also by 2020, the Daniel K. Inouye Solar Telescope will come online in Hawaii, where it will make daily maps of the solar corona.
For his part, the 91-year-old Parker says that he is looking forward to seeing the waves and turbulence in the solar wind — which he predicted — measured by the probe that bears his name. “I expect to find some surprises,” he says.
www.nature.com/articles/d41586-018-05741-6
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Post by swamprat on Jul 20, 2018 9:34:39 GMT -6
Traveling to the sun: Why won't Parker Solar Probe melt?Date: July 19, 2018 Source: NASA/Goddard Space Flight Center
Summary: This summer, NASA's Parker Solar Probe will launch to travel closer to the Sun, deeper into the solar atmosphere, than any mission before it. If Earth was at one end of a yard-stick and the Sun on the other, Parker Solar Probe will make it to within four inches of the solar surface. Cutting-edge technology and engineering will help it beat the heat.
Inside that part of the solar atmosphere, a region known as the corona, Parker Solar Probe will provide unprecedented observations of what drives the wide range of particles, energy and heat that course through the region -- flinging particles outward into the solar system and far past Neptune.
Inside the corona, it's also, of course, unimaginably hot. The spacecraft will travel through material with temperatures greater than a million degrees Fahrenheit while being bombarded with intense sun light.
So, why won't it melt?
Parker Solar Probe has been designed to withstand the extreme conditions and temperature fluctuations for the mission. The key lies in its custom heat shield and an autonomous system that helps protect the mission from the Sun's intense light emission, but does allow the coronal material to "touch" the spacecraft.
The Science Behind Why It Won't Melt One key to understanding what keeps the spacecraft and its instruments safe, is understanding the concept of heat versus temperature. Counterintuitively, high temperatures do not always translate to actually heating another object.
In space, the temperature can be thousands of degrees without providing significant heat to a given object or feeling hot. Why? Temperature measures how fast particles are moving, whereas heat measures the total amount of energy that they transfer. Particles may be moving fast (high temperature), but if there are very few of them, they won't transfer much energy (low heat). Since space is mostly empty, there are very few particles that can transfer energy to the spacecraft.
The corona through which Parker Solar Probe flies, for example, has an extremely high temperature but very low density. Think of the difference between putting your hand in a hot oven versus putting it in a pot of boiling water (don't try this at home!) -- in the oven, your hand can withstand significantly hotter temperatures for longer than in the water where it has to interact with many more particles. Similarly, compared to the visible surface of the Sun, the corona is less dense, so the spacecraft interacts with fewer hot particles and doesn't receive as much heat.
That means that while Parker Solar Probe will be traveling through a space with temperatures of several million degrees, the surface of the heat shield that faces the Sun will only get heated to about 2,500 degrees Fahrenheit (about 1,400 degrees Celsius).
The Shield That Protects It Of course, thousands of degrees Fahrenheit is still fantastically hot. (For comparison, lava from volcano eruptions can be anywhere between 1,300 and 2,200 F (700 and 1,200 C) And to withstand that heat, Parker Solar Probe makes use of a heat shield known as the Thermal Protection System, or TPS, which is 8 feet (2.4 meters) in diameter and 4.5 inches (about 115 mm) thick. Those few inches of protection mean that just on the other side of the shield, the spacecraft body will sit at a comfortable 85 F (30 C).
The TPS was designed by the Johns Hopkins Applied Physics Laboratory, and was built at Carbon-Carbon Advanced Technologies, using a carbon composite foam sandwiched between two carbon plates. This lightweight insulation will be accompanied by a finishing touch of white ceramic paint on the sun-facing plate, to reflect as much heat as possible. Tested to withstand up to 3,000 F (1,650 C), the TPS can handle any heat the Sun can send its way, keeping almost all instrumentation safe.
The Cup that Measures the Wind But not all of the Solar Parker Probe instruments will be behind the TPS. Poking out over the heat shield, the Solar Probe Cup is one of two instruments on Parker Solar Probe that will not be protected by the heat shield. This instrument is what's known as a Faraday cup, a sensor designed to measure the ion and electron fluxes and flow angles from the solar wind. Due to the intensity of the solar atmosphere, unique technologies had to be engineered to make sure that not only can the instrument survive, but also the electronics aboard can send back accurate readings.
The cup itself is made from sheets of Titanium-Zirconium-Molybdenum, an alloy of molybdenum, with a melting point of about 4,260 F (2,349 C). The chips that produce an electric field for the Solar Probe Cup are made from tungsten, a metal with the highest known melting point of 6,192 F (3,422 C). Normally lasers are used to etch the gridlines in these chips -- however due to the high melting point acid had to be used instead.
Another challenge came in the form of the electronic wiring -- most cables would melt from exposure to heat radiation at such close proximity to the Sun. To solve this problem, the team grew sapphire crystal tubes to suspend the wiring, and made the wires from niobium.
To make sure the instrument was ready for the harsh environment, the researchers needed to mimic the Sun's intense heat radiation in a lab. To create a test-worthy level of heat, the researchers used a particle accelerator and IMAX projectors -- jury-rigged to increase their temperature. The projectors mimicked the heat of the Sun, while the particle accelerator exposed the cup to radiation to make sure the cup could measure the accelerated particles under the intense conditions. To be absolutely sure the Solar Probe Cup would withstand the harsh environment, the Odeillo Solar Furnace -- which concentrates the heat of the Sun through 10,000 adjustable mirrors -- was used to test the cup against the intense solar emission.
The Solar Probe Cup passed its tests with flying colors -- indeed, it continued to perform better and give clearer results the longer it was exposed to the test environments. "We think the radiation removed any potential contamination," Justin Kasper, principal investigator for the SWEAP instruments at the University of Michigan in Ann Arbor, said. "It basically cleaned itself."
The Spacecraft That Keeps its Cool Several other designs on the spacecraft keep Parker Solar Probe sheltered from the heat. Without protection, the solar panels -- which use energy from the very star being studied to power the spacecraft -- can overheat. At each approach to the Sun, the solar arrays retract behind the heat shield's shadow, leaving only a small segment exposed to the Sun's intense rays.
But that close to the Sun, even more protection is needed. The solar arrays have a surprisingly simple cooling system: a heated tank that keeps the coolant from freezing during launch, two radiators that will keep the coolant from freezing, aluminum fins to maximize the cooling surface, and pumps to circulate the coolant. The cooling system is powerful enough to cool an average sized living room, and will keep the solar arrays and instrumentation cool and functioning while in the heat of the Sun.
The coolant used for the system? About a gallon (3.7 liters) of deionized water. While plenty of chemical coolants exist, the range of temperatures the spacecraft will be exposed to varies between 50 F (10 C) and 257 F (125 C). Very few liquids can handle those ranges like water. To keep the water from boiling at the higher end of the temperatures, it will be pressurized so the boiling point is over 257 F (125 C).
Another issue with protecting any spacecraft is figuring out how to communicate with it. Parker Solar Probe will largely be alone on its journey. It takes light eight minutes to reach Earth -- meaning if engineers had to control the spacecraft from Earth, by the time something went wrong it would be too late to correct it.
So, the spacecraft is designed to autonomously keep itself safe and on track to the Sun. Several sensors, about half the size of a cell phone, are attached to the body of the spacecraft along the edge of the shadow from the heat shield. If any of these sensors detect sunlight, they alert the central computer and the spacecraft can correct its position to keep the sensors, and the rest of the instruments, safely protected. This all has to happen without any human intervention, so the central computer software has been programmed and extensively tested to make sure all corrections can be made on the fly.
Launching toward the Sun After launch, Parker Solar Probe will detect the position of the Sun, align the thermal protection shield to face it and continue its journey for the next three months, embracing the heat of the Sun and protecting itself from the cold vacuum of space.
Over the course of seven years of planned mission duration, the spacecraft will make 24 orbits of our star. On each close approach to the Sun it will sample the solar wind, study the Sun's corona, and provide unprecedentedly close up observations from around our star -- and armed with its slew of innovative technologies, we know it will keep its cool the whole time.
Story Source: Materials provided by NASA/Goddard Space Flight Center. Note: Content may be edited for style and length.
www.sciencedaily.com/releases/2018/07/180719165026.htm
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Post by swamprat on Jul 20, 2018 11:45:31 GMT -6
"PSP-Certificate-FF92CB74-99C8-CF67-CDE7-E03"
Cool!
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Post by jcurio on Jul 21, 2018 7:15:12 GMT -6
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Post by swamprat on Jul 23, 2018 8:36:43 GMT -6
Will Parker Solar Probe Really 'Touch the Sun'?By Elizabeth Howell, Live Science Contributor | July 23, 2018
Next month, NASA will give the sun its close-up. The Parker Solar Probe will begin a seven-year mission to examine the sun's energy, in an effort to better protect people and spacecraft from the star's potentially devastating effects. A particularly lofty milestone for the probe? "Touching the sun," NASA says.
Considering the sun is a ball of sizzling gas — with no solid surface — what, exactly, does that mean?
After it launches, no earlier than Aug. 4, Parker will periodically fly through the outermost layer of the sun's atmosphere, called the corona, WHERE TEMPERATURES CAN SOAR AS HIGH AS 3.5 MILLION DEGREES FAHRENHEIT (2 MILLION DEGREES CELSIUS). The only reason Parker can survive is because the corona's density is so low. Low density slows heat transfer.
Even more bizarre, the sun's corona is 300 times hotter than the photosphere — the lowest layer of the sun's atmosphere, where solar flares belch and sunspots form. (Why that's the case is still a mystery – that's one question Parker is designed to answer.) And as the corona billows out into space as a stream of charged particles known as the solar wind, the superheated gas cools.
Because of the extreme temperatures, sun-observing spacecraft have trouble getting close enough to get a complete picture of the corona's activity. So, the Parker Solar Probe, equipped with special shielding, will zoom in to just 4 million miles (6.4 million kilometers) from the sun's photosphere to get close-up views. That's more than 14 times closer than Mercury is to the sun — a distance that averages of 58 million miles (93 million km). And it will be the closest that any human-made object has been to the sun — essentially, Parker will "touch the sun."
"Parker is going to be the first time where we're going to get close enough to the sun to see where the action is happening, where the corona is heated and where the solar wind is being accelerated," Eric Christian, a research scientist on the Parker mission at NASA's Goddard Space Flight Center in Greenbelt, Maryland, told Live Science.
Parker's main science goals are to understand how the solar wind is accelerated and why the corona is superhot. These are important science and exploration questions, Christian said. The sun periodically sends out solar flares and, along with them, coronal mass ejections that can carry dangerous charged particles across the solar system.
Parker's heat shield is a lightweight, 4.5-inch thick carbon foam core that is 97 percent air, according to NASA. Surrounding it is two panels of superheated carbon-carbon composite. The side closest to the sun was spray-coated to reflect the star's energy, allowing the spacecraft to stay as cool as possible.
The spacecraft will be so close to the sun that it won't be able to take pictures while looking straight at it, because otherwise it will be damaged. So NASA will depend on its fleet of other sun spacecraft to show how the sun looks while Parker collects information about the star's activity. The Solar Dynamics Observatory and the Solar and Heliospheric Observatory already do regular observations of the star from afar to monitor its sunspots, flares and other indications of solar activity, so they'll continue doing that job while Parker gets its close-up view.
Parker's first glimpse of the sun from up close will happen just four months after launch. First, it will do a quick flyby of Venus. However, Christian said science observations at the planet are unlikely because Parker's instruments are designed to pick up charged particles, and Venus doesn't have much of a magnetic field. Then, Parker will dip as close as 17 million miles (27 million km) from the sun in this particular flyby, autonomously collecting observations and then slowly transmitting them back to Earth the following year, Christian said.
Why the delay? The sun is a powerful source of radio waves, and it can interfere with Parker's communications. While Parker is close to the sun and orbiting near the sun (relative to Earth's view), NASA will avoid getting in touch with the probe, so that the space agency's commands don't confuse the spacecraft. NASA is already used to such situations, such as when Mars gets close to the sun (from Earth's perspective) and the agency suspends conversations with rovers on the surface.
Christian said he can't wait to see what Parker will show us about the sun. Compared with terrestrial weather forecasting, he said, our solar weather predictions "are way behind … We can't forecast when the sun will give off these storms," he said. But with more data, scientists may someday understand solar weather as well as they do tornado formation on Earth today, he said.
www.livescience.com/63130-will-solar-probe-touch-the-sun.html
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Post by swamprat on Aug 9, 2018 8:57:28 GMT -6
A spacecraft to touch the sunBy Deborah Byrd in HUMAN WORLD | SPACE | August 9, 2018
Set to launch August 11, the daredevil Parker Solar Probe will get closer to the sun than any spacecraft in human history.
Illustration of NASA's Parker Solar Probe in front of the Sun Credits: NASA/Johns Hopkins APL/Steve Gribben
Spoiler ahead … Sci fi fans! Remember that great scene in Battlestar Galactica, when Anders took control of the abandoned fleet and piloted it into the sun? Recall it this weekend, as NASA launches its newest mission, the Parker Solar Probe. The craft is destined to go, if not directly into the sun, at least closer to our local star than any spacecraft before. On its seven-year mission, the craft will whip through the sun’s sizzling outer atmosphere, or corona, swooping to within 4 million miles (6.4 million km) of the sun’s surface. Set to launch on August 11, 2018, this craft will face heat and radiation like no spacecraft before it. Why won’t it melt? Explanation here.
Scientists hope that – if it does survive its fiery journey so close to our local star – the Parker Solar Probe’s instruments will provide data leading to better predictions of space weather, which begins at the sun and ultimately can wreak havoc on human technologies on Earth and in space.
The scientists also hope the Parker Solar Probe will help them address fundamental questions about the sun’s dynamic and mysterious corona.
The Parker Solar Probe – named for Eugene Parker, who first theorized that the sun constantly sends out a flow of particles and energy called the solar wind – will explore one of the last regions of the solar system to be visited by a spacecraft.
Keep up with the latest on the sun at @nasasun on Twitter.
Join NASA live on Thursday, August 9, at 17:00 UTC (1:00 p.m. EDT; translate UTC to your time) for a pre-launch briefing about Parker Solar Probe. You’ll hear from scientists, mission experts and launch team members. That’s at nasa.gov/live, or watch on Facebook.
Parker Solar Probe will lift off on a United Launch Alliance Delta IV Heavy rocket from Space Launch Complex 37 on Cape Canaveral Air Force Station in Florida. The first launch opportunity is at 3:33 a.m. EDT, at the opening of a 65-minute window.
SOURCE: NASA and Space.com
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Post by swamprat on Aug 11, 2018 7:50:42 GMT -6
Sigh..... I got up at 3:30 to watch.....
Parker Solar Probe New Launch Date is Aug. 12
5 hours ago The launch of a United Launch Alliance Delta IV Heavy rocket carrying the Parker Solar Probe spacecraft was scrubbed today due to a violation of a launch limit, resulting in a hold. There was not enough time remaining in the window to recycle. The launch is planned for Sunday, Aug. 12 from Space Launch Complex-37 at Cape Canaveral Air Force Station. The forecast shows a 60 percent chance of favorable weather conditions for launch. The launch time is 3:31 a.m. EDT.
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Post by swamprat on Aug 11, 2018 9:34:12 GMT -6
See Scientist Eugene Parker Bid Farewell to the Sun Probe NASA Named for HimBy Meghan Bartels, Space.com Senior Writer | August 10, 2018
NASA Science Mission Directorate Associate Administrator Thomas Zurbuchen, solar astrophysicist Eugene Parker and United Launch Alliance President Tory Bruno in front of the rocket that will carry the Parker Solar Probe into space. Credit: NASA/Bill Ingalls
It's never too late to do something for the first time — especially if that thing is seeing a rocket launch in person, and even more so if that rocket is carrying a mission named after you.
At 91, renowned solar scientist Eugene Parker is experiencing just that this weekend as NASA launches its Parker Solar Probe, a seven-year, $1.5 billion mission to "touch the sun."
Parker, now retired from the University of Chicago, spent his career trying to understand the sun and the ways it affects the solar system. In 1958, he hypothesized the existence of the solar wind, the constant rush of highly charged particles that constantly streams off the sun. And now, six decades later, a spacecraft that will revolutionize our understanding of the phenomenon is prepared to launch.
Since the mission was named in his honor last year, NASA has offered Parker special behind-the-scenes access to the spacecraft carrying his name. He previously toured the facility where the spacecraft was built, and now he is in Florida, visiting NASA's Kennedy Space Center.
Parker also received a tour of Kennedy Space Center. Credit: NASA/Kennedy Space Center/Sandy Hillman Communications
Today (Aug. 10), accompanied by NASA Science Mission Directorate Associate Administrator Thomas Zurbuchen, project scientist Nicola Fox of Johns Hopkins University, and United Launch Alliance President Tory Bruno, Parker admired the Delta IV Heavy rocket with the probe in its tip. The spacecraft is NOW scheduled to launch tomorrow (Aug. 12) at 3:31 a.m. (0731 GMT).
Parker has never seen a launch in person before.
We can't offer quite the same experience, but you can watch the launch live here on Space.com, courtesy of NASA TV.
www.space.com/41453-scientist-eugene-parker-solar-probe-farewell-photos.html
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Post by swamprat on Aug 12, 2018 8:59:00 GMT -6
I saw it from my front yard! A tiny red light rising in the southeast!
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Post by swamprat on Aug 19, 2018 18:32:55 GMT -6
Parker Solar Probe Marks First Mission Milestones on Voyage to SunJust two days after launch on Aug. 11, 2018, from Cape Canaveral Air Force Station in Florida, NASA’s Parker Solar Probe achieved several planned milestones toward full commissioning and operations, announced mission controllers at the Johns Hopkins Applied Physics Laboratory, or APL, in Laurel, Maryland.
On Aug. 13, the high-gain antenna, which Parker Solar Probe uses to communicate high-rate science data to Earth, was released from locks which held it stable during launch. Controllers have also been monitoring the spacecraft as it autonomously uses its thrusters to remove (or “dump”) momentum, which is part of the flight operations of the spacecraft. Managing momentum helps the spacecraft remain in a stable and optimal flight profile.
There are four instrument suites on board Parker Solar Probe, which will each need to be powered and readied for science data collection. The FIELDS investigation, which consists of the most elements, went first. It was powered up on Aug. 13 for two activities. First was the opening of the clamps which held four of the five FIELDS antennas stowed during takeoff. These antennas will be deployed roughly 30 days after launch, and they will stick out from the corners of the spacecraft’s heat shield — called the Thermal Protection System — and be exposed to the harsh solar environment. Second, the spacecraft’s magnetometer boom was fully deployed. This boom contains three magnetometers and a fifth, smaller electric field antenna, all part of the FIELDS suite. Further instrument check-outs and deployments are scheduled in the coming days for the spacecraft.
As of 12:00 p.m. EDT on Aug. 16, Parker Solar Probe was 2.9 million miles from Earth, traveling at 39,000 miles per hour, and heading toward its first Venus flyby scheduled for Oct. 3, 2018, at 4:44 a.m. EDT. The spacecraft will use Venus to slightly slow itself and adjust its trajectory for an optimal path toward first perihelion of the Sun on Nov. 5, 2018, at 10:27 p.m. EST (Nov. 6, 2018, at 03:27 UTC).
“Parker Solar Probe is operating as designed, and we are progressing through our commissioning activities,” said Project Manager Andy Driesman of APL. “The team — which is monitoring the spacecraft 24 hours a day, seven days a week — is observing nominal data from the systems as we bring them on-line and prepare Parker Solar Probe for its upcoming initial Venus gravity assist.”
By Geoff Brown Johns Hopkins University Applied Physics Lab blogs.nasa.gov/parkersolarprobe/2018/08/17/parker-solar-probe-marks-first-mission-milestones-on-voyage-to-sun/
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