23.05.2018
More Than 1.1 Million Names Installed on NASA’s Parker Solar Probe
Throughout its seven-year mission, NASA’s Parker Solar Probe will swoop through the Sun’s atmosphere 24 times, getting closer to our star than any spacecraft has gone before. The spacecraft will carry more than scientific instruments on this historic journey — it will also hold more than 1.1 million names submitted by the public to go to the Sun.
“Parker Solar Probe is going to revolutionize our understanding of the Sun, the only star we can study up close,” said Nicola Fox, project scientist for Parker Solar Probe at the Johns Hopkins Applied Physics Lab in Laurel, Maryland. “It’s fitting that as the mission undertakes one of the most extreme journeys of exploration ever tackled by a human-made object, the spacecraft will also carry along the names of so many people who are cheering it on its way.”
“Let’s see what lies ahead.”
– Gene Parker, July 2017
Back in March 2018, the public were invited to send their names to the Sun aboard humanity’s first mission to “touch” a star. A total of 1,137,202 names were submitted and confirmed over the seven-and-a-half-week period, and a memory card containing the names was installed on the spacecraft on May 18, 2018, three months before the scheduled launch on July 31, 2018, from NASA’s Kennedy Space Center in Florida. The card was mounted on a plaque bearing a dedication to and a quote from the mission’s namesake, heliophysicist Eugene Parker, who first theorized the existence of the solar wind. This is the first NASA mission to be named for a living individual.
This memory card also carries photos of Parker, professor emeritus at the University of Chicago, and a copy of his groundbreaking 1958 scientific paper. Parker proposed a number of concepts about how stars — including our Sun — give off material. He called this cascade of energy and particles the solar wind, a constant outflow of material from the Sun that we now know shapes everything from the habitability of worlds to our solar system’s interaction with the rest of the galaxy.
Parker Solar Probe will explore the Sun’s outer atmosphere and make critical observations to answer decades-old questions about the physics of stars. The resulting data may also improve forecasts of major eruptions on the Sun and subsequent space weather events that impact life on Earth, as well as satellites and astronauts in space.
A memory card containing 1,137,202 names submitted by the public to travel to the Sun was installed on Parker Solar Probe on May 18, 2018.
Credits: NASA/Johns Hopkins APL/Ed Whitman
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Though our understanding of the Sun and the solar wind has vastly improved since Parker first theorized the solar wind, there are still questions left unanswered. Two of the most fundamental mysteries – which scientists hope Parker Solar Probe will help solve – are the coronal heating problem and the mechanism behind solar wind acceleration.
In addition to a chip containing submitted names, the plaque installed on the Parker Solar Probe spacecraft also contains a dedication to and quote from Eugene Parker, the mission’s namesake. It reads: "The Parker Solar Probe mission is dedicated to Dr. Eugene N. Parker whose profound contributions have revolutionized our understanding of the Sun and solar wind. 'Let's see what lies ahead' Gene Parker, July 2017"
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The coronal heating problem is what scientists call the apparent mismatch between the temperature of the Sun’s photosphere — the visible “surface,” measuring about 10,000 degrees Fahrenheit — and the much higher temperature of the corona — the Sun’s atmosphere, which reaches temperatures of up to 10 million degrees Fahrenheit. Since the Sun’s energy source is at its core, this increase is similar to walking away from a campfire and suddenly feeling a thousand times hotter — completely counterintuitive. This implies that some other process is continually adding more heat to that solar atmosphere.
Scientists think that the mechanism behind this as-yet unexplained heating happens in the lower corona — and Parker Solar Probe will get closer to this region than any spacecraft has before. Getting a closer look at this region should help scientists identify the source of this coronal heating, along with pinpointing the process that accelerates the solar wind to enormous speeds as it leaves the Sun.
A commemorative reproduction of the plaque bearing an identical memory card — minus the submitted names — was presented to Parker at the Johns Hopkins University Applied Physics Lab in October 2017 by the mission team.
"From the experience of seeing the probe up close, I understand now the difficult task you are undertaking, and I am sure you will succeed,” said Parker after visiting the spacecraft in the clean room.
The plaque containing names submitted to travel to the Sun is mounted below Parker Solar Probe’s high-gain antenna (the round object with gray covering), which the spacecraft will use to transmit data back to Earth.
Credits: NASA/Johns Hopkins APL/Ed Whitman
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Parker Solar Probe is part of NASA’s Living with a Star Program, or LWS, to explore aspects of the Sun-Earth system that directly affect life and society. LWS is managed by NASA’s Goddard Space Flight Center in Greenbelt, Maryland, for the Heliophysics Division of NASA’s Science Mission Directorate in Washington. Johns Hopkins APL manages the Parker Solar Probe mission for NASA. APL designed and built the spacecraft and will also operate it.
Quelle: NASA,ULA
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Update:7.07.2018
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NASA’s Parker probe is about to get up close and personal with the sun
The spacecraft, set to launch August 4, will get within 6 million kilometers of our star
NASA’s Parker Solar Probe is about to embark on one daredevil stunt of a space mission.
Slated to launch August 4, the probe will be the first spacecraft to swoop through the sun’s outer atmosphere, or corona, a roiling inferno of plasma heated to several million degrees Celsius.
Parker will whip around the sun two dozen times over the next seven years, skirting within about 6 million kilometers of the star’s surface — more than seven times as close as any previous spacecraft. At its nearest approach, Parker will hurtle through the corona at about 700,000 kilometers per hour, making the craft the fastest human-made object in the solar system. The probe would need only about a second to zip from Philadelphia to Washington, D.C.
Parker’s closeup observations of the corona and the solar wind, the torrent of charged particles that the sun spews into space, could help resolve long-standing mysteries about the inner workings of the sun’s atmosphere. And the new data may improve forecasts for space weather that endangers spacecraft, astronauts and technology on the ground.
The trove of new data gathered by this probe “is going to answer a lot of questions that we couldn’t answer in any other way,” says Craig DeForest, a heliophysicist at the Southwest Research Institute in Boulder, Colo., who is not involved in the mission. “There’s been a tremendous amount of anticipation.”
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IN THE THICK OF IT This view of the sun, as seen the by a coronagraph onboard the Solar and Heliospheric Observatory spacecraft, reveals the turbulent structure of the sun’s outer atmosphere, or corona. Parker will be the first probe to soar through this searing plasma. |
Scientists have had a probe like Parker on their mission wish lists for nearly 60 years. In 1958, the year that NASA was created, the National Academies’ Space Studies Board recommended that the new agency send a spacecraft inside the orbit of Mercury to investigate the environment surrounding the sun.
Over the years, several research groups have floated solar probe mission ideas, but none could get as close to the sun as astronomers wanted. “It’s only been recently that the technology of heat shields and everything else has converged well enough that we could make this a reality,” DeForest says.
About the size of a small car, the Parker Solar Probe will pack instruments to take 3-D images, measure electric and magnetic fields and catalog high-energy particles. Although the corona sizzles at millions of degrees, the atmosphere is so diffuse that most of the heat that will imperil Parker’s instruments comes from radiation emanating directly from the sun’s surface. This lethally intense sunlight can heat the face of the spacecraft to about 1370°.
To guard Parker’s instruments against that radiation, the probe is armed with a heat shield composed of a layer of carbon foam sandwiched between panes of another carbon-based material similar to the graphite epoxy used to make golf clubs and tennis rackets. As Parker swings around the sun, this heat shield will continuously face the star to keep the instruments tucked behind it safe from radiation up to about 475 times as intense as what Earth-orbiting spacecraft endure.
Parker will dive into the sun’s corona for the first time just three months after launch, sending its first batch of data back to Earth in early December. For scientists, that’s pretty quick gratification: For spacecraft such as New Horizons (SN Online: 6/15/15) that have rendezvoused with more distant solar system objects, the intermission between launch and arrival can span years.
The probe will circle the sun 24 times, using Venus’ gravitational pull to gradually shrink the craft’s orbit. On its first go-round, Parker will fly to about 24 million kilometers from the sun’s surface; on its final few loops in 2024 and 2025, the probe will get within about 6 million kilometers.
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ROUND AND ROUND The Parker probe will circle the sun 24 times over the next seven years, using the gravitational tug of Venus to gradually shrink its own orbit. On its first go-round, Parker will get as close as 24 million kilometers to the surface of the star. On its final few loops, beginning in 2024, the probe will skirt within about 6 million kilometers of the sun’s surface. |
The probe may have some fuel left over to keep cruising around the sun after completing its mission-mandated 24 orbits, says Nicola Fox, project scientist for the mission. But eventually, Parker won’t be able to fire the thrusters that it needs to keep its heat shield aimed at the sun. The probe “will start to turn, and bits of the spacecraft that are totally not designed to see the sun will be in full illumination,” says Fox, a heliophysicist at the Johns Hopkins Applied Physics Laboratory in Laurel, Md. “The spacecraft will break up into kind of large chunks at first, and then they’ll get smaller and smaller.” Eventually, Parker will be nothing more than a smattering of dust scattered across the corona.
The spacecraft’s legacy, however, will live on. Parker’s observations are expected to help answer questions about the corona and solar wind that researchers have puzzled over for decades.
For instance, Parker data could explain the strange temperature difference between the surface of the sun, which is a toasty 5500°, and the several-million-degree corona. This spike may be due to vibrating magnetic field lines heating up material in the corona, or jets of material from the sun’s surface that inject energy into its atmosphere (SN Online: 8/20/17). Parker could also help explain where solar wind particles get the energy to speed up as they escape the sun’s immense gravitational pull (SN Online: 8/18/17).
The enigmatic coronal heat and acceleration of the solar wind probably have a common cause, says David McComas, a space plasma physicist at Princeton University. McComas is the principal investigator for one of the probe’s instruments, the Integrated Science Investigation of the Sun. There are many competing theories to explain these two problems, but Parker’s views of the sun should help winnow down the list of possible explanations.
Parker’s observations should also give new insight into the origins of those highly energetic particles that escape the sun into the solar wind, McComas says. The solar wind washes over Earth at hundreds of kilometers per second, and disturbances in this cosmic breeze can mess with satellites, spacecraft and power grids (SN: 8/19/06, p. 120). A better understanding of the sun’s tumultuous atmosphere and solar wind could lead to better forecasts for potentially dangerous space weather events.
On top of all that, Parker’s zoomed-in view of the sun will undoubtedly raise new mysteries about our home star, McComas says. The data haul from “one mission [often] just whets our appetites for even more observations down the road,” he says.
Fortunately, another spacecraft bound for the sun is launching right on the heels of the Parker probe. The European Space Agency’s Solar Orbiter, set to take flight in 2020, will provide the first direct images of the sun’s poles. Paired with Parker’s observations closer to the sun’s midriff, Solar Orbiter data may reveal how the solar wind varies at different latitudes.
SPACECRAFT: ATG MEDIALAB/ESA; SUN: P. TESTA (CFA)/SDO/NASA
These missions aren’t just about getting to know our own solar system. “Once you know about how our star works, you’re going to know a lot more about … other stars,” Fox says.
Whatever scientific discoveries come from the mission, it’s difficult not to get excited for the sheer “wow” factor of the probe’s impending expedition. “This is really freaking cool,” DeForest says. “We’re launching a probe and flying it through [several-] million-degree plasma on the periphery of a star. I mean, how cool is that?”
Quelle: ScienceNews
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Update: 8.07.2018
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Delta-IV Heavy Undergoing Wet Dress Rehearsals as Parker Solar Probe Nears August 4 Launch
A United Launch Alliance (ULA) Delta-IV Heavy underling a Wet Dress Rehearsal on Space Launch Complex 37B for NASA’s upcoming Parker Solar Probe launch, slated for no earlier than August 4, 2018. Photo Credit: ULA
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The United Launch Alliance (ULA) rocket slated to launch humanity’s first mission to ‘touch’ a star is spending this week undergoing critical pre-flight testing with two Wet Dress Rehearsals (WDR), or practice countdowns, at Space Launch Complex 37 at Cape Canaveral Air Force Station in Florida, to ensure everything is GO for a launch attempt next month with NASA’s Parker Solar Probe spacecraft.
Currently the largest and most powerful rocket used by NASA, the 177-foot tall Delta IV Heavy (without payload fairing) was rolled out from its Horizontal Integration Facility and raised atop launch pad 37B back on April 17, and has since been undergoing preparations for a launch attempt as soon as August 4, with liftoff scheduled for shortly after 4:00 a.m. EDT.
ULA conducted a successful initial WDR on Monday, July 2, which focused on “first stage objectives” with fueling of the vehicle’s three 134-foot tall Common Booster Cores, which are powered by a trio of RS-68A cryogenic liquid hydrogen/liquid oxygen burning engines.
The United Launch Alliance Delta IV Heavy that will carry Parker Solar Probe is raised at Launch Complex 37 at Cape Canaveral Air Force Station in Florida on April 17, 2018. Credit: NASA/Johns Hopkins APL/Ed Whitman
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Today (Friday, July 6), teams are conducting another WDR, a full blown countdown to a simulated liftoff, aiming “to complete all objectives including second stage tanking,” according to ULA. The rocket’s second stage is powered by a single cryogenic liquid hydrogen/liquid oxygen burning RL10 engine.
A WDR helps uncover any issues and validates that the launcher, systems, launch team and ground support equipment are all ready for flight, and ULA says so far so good; on their end all is on track for a launch attempt no earlier than August 4.
Built by the Johns Hopkins Applied Physics Laboratory in Laurel, Maryland, the car-sized spacecraft demands a lot from the launch; Parker Solar Probe will be the fastest human-made object in the solar system when it makes its closest approaches 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.
Using the gravitational tug of Venus to gradually shrink its orbit, the spacecraft will come closer to our star than any spacecraft has before, facing brutal heat and radiation, in order to provide the first ever samplings of a star’s corona, which is visible to the human eye during a total solar eclipse and can reach temperatures upwards of 10 million degrees Fahrenheit.
But in order to do this, the spacecraft demands an extremely high energy launch, and so the Delta IV Heavy’s capability will be augmented by a powerful third stage from Northrop Grumman Innovation Systems.
“Parker Solar Probe is going to revolutionize our understanding of the Sun, the only star we can study up close,” said Nicola Fox, project scientist for Parker Solar Probe at the Johns Hopkins Applied Physics Lab in Laurel, Maryland. “The mission undertakes one of the most extreme journeys of exploration ever tackled by a human-made object.”
The ultimate goal overall is to understand how the Sun works and how it affects the space environment, to the point of predictability. We’ll have more in-depth articles in the coming weeks on specifics about the science Parker Solar Probe will conduct, and how it will do so, including interviews with mission team members (so stay tuned).
The spacecraft itself is currently in a clean room at Astrotech Space Operations in nearby Titusville, Florida, where it arrived from NASA’s Goddard Space Flight Center in Greenbelt, Maryland on April 2, via a U.S. Air Force C-17 aircraft, for final comprehensive testing, assembly, fueling and mating to the Delta-IV Heavy’s thirst stage.
The spacecraft is expected to be transported to Launch Complex 37 to meet its rocket in mid-July.
Quelle: AS
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Update: 9.07.2018
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Cutting-Edge Heat Shield Installed on NASA’s Parker Solar Probe
The launch of Parker Solar Probe, the mission that will get closer to the Sun than any human-made object has ever gone, is quickly approaching, and on June 27, 2018, Parker Solar Probe’s heat shield — called the Thermal Protection System, or TPS — was installed on the spacecraft.
A mission 60 years in the making, Parker Solar Probe will make a historic journey to the Sun’s corona, a region of the solar atmosphere. With the help of its revolutionary heat shield, now permanently attached to the spacecraft in preparation for its August 2018 launch, the spacecraft’s orbit will carry it to within 4 million miles of the Sun's fiercely hot surface, where it will collect unprecedented data about the inner workings of the corona.
Parker Solar Probe’s heat shield, called the Thermal Protection System, is lifted and realigned with the spacecraft’s truss as engineers from the Johns Hopkins Applied Physics Lab prepare to install the eight-foot-diameter heat shield on June 27, 2018.
Credits: NASA/Johns Hopkins APL/Ed Whitman
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The eight-foot-diameter heat shield will safeguard everything within its umbra, the shadow it casts on the spacecraft. At Parker Solar Probe’s closest approach to the Sun, temperatures on the heat shield will reach nearly 2,500 degrees Fahrenheit, but the spacecraft and its instruments will be kept at a relatively comfortable temperature of about 85 degrees Fahrenheit.
The heat shield is made of two panels of superheated carbon-carbon composite sandwiching a lightweight 4.5-inch-thick carbon foam core. The Sun-facing side of the heat shield is also sprayed with a specially formulated white coating to reflect as much of the Sun’s energy away from the spacecraft as possible.
The heat shield itself weighs only about 160 pounds — here on Earth, the foam core is 97 percent air. Because Parker Solar Probe travels so fast — 430,000 miles per hour at its closest approach to the Sun, fast enough to travel from Philadelphia to Washington, D.C., in about one second — the shield and spacecraft have to be light to achieve the needed orbit.
The reinstallation of the Thermal Protection System — which was briefly attached to the spacecraft during testing at the Johns Hopkins Applied Physics Lab in Laurel, Maryland, in fall 2017 — marks the first time in months that Parker Solar Probe has been fully integrated. The heat shield and spacecraft underwent testing and evaluation separately at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, before shipping out to Astrotech Space Operations in Titusville, Florida, in April 2018. With the recent reunification, Parker Solar Probe inches closer to launch and toward the Sun.
Parker Solar Probe is part of NASA’s Living with a Star Program, or LWS, to explore aspects of the Sun-Earth system that directly affect life and society. LWS is managed by Goddard for the Heliophysics Division of NASA’s Science Mission Directorate in Washington, D.C. The Johns Hopkins Applied Physics Laboratory manages the Parker Solar Probe mission for NASA. APL designed and built the spacecraft and will also operate it.
The Thermal Protection System connects to the custom-welded truss on the Parker Solar Probe spacecraft at six points to minimize heat conduction.
Quelle: NASA
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Update: 17.07.2018
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A LOOK BEHIND THE SCENES AT THE PARKER SOLAR PROBE
Videographer Lee Hobson and photographer Ed Whitman spend their days documenting mankind's mission to "touch" the sun
Lee Hobson and Ed Whitman flew to Florida in style three months ago, touching down in the Sunshine State in a Boeing C-17 loaded with priceless cargo: the Parker Solar Probe.
Hobson, director of photography for the Johns Hopkins Applied Physics Laboratory, is the video documentary lead for the APL-led mission to "touch" the sun. He and Whitman, APL's senior photographer, have spent the past four years painstakingly documenting the construction and testing of the probe, which is scheduled to launch in August. Flying through the sun's corona, or atmosphere, and facing heat and radiation like no spacecraft before it, the Parker Solar Probe will provide new data on solar activity and make critical contributions to scientists' ability to forecast major space-weather events that impact life on Earth.
The Hub caught up with Hobson and Whitman to talk about their work, the mission, and what it's like to stand in the presence of the spacecraft that could change humanity's understanding of Earth's closest star.
How did you get involved with APL and documenting its projects?
Ed Whitman: As a kid, I was always fascinated with how things worked. There was nothing in my home that was safe from me and a screwdriver. I knew early on that I wanted to do photography, and I had my own company for many years, but when the opportunity at APL came up it just seemed like the right fit. I took the position and just loved it because, you know, I'm basically a frustrated engineer.
Lee Hobson: I joined in 1988 as a staff photographer and then moved into the video sector in 1996. On any given day I could be working in air defense or force projections, or national security analysis and research, or of course space exploration. That's what's really cool about APL—there's a lot of different things we work on.
"[W]e're working next to the spacecraft that's going to fly within 4 million miles of the sun, and I get to walk around the launchpad. That's really cool," says Hobson.
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What's it like to document the Parker Solar Probe?
LH: The average day is about 10 hours here, but it's sometimes as long as 15 hours depending on what we're doing. Ed and I are unique in that when the day's operation is finished, we don't go home, we come back to the office to edit footage. So it can be a really long day.
EW: We do press releases for the public, and those are more like the milestone events when significant things happen. But day to day, I'm working with the mechanical team, shooting everything that's being integrated into the spacecraft—every nut, every bolt, every process that takes place. And that's helpful because if the mechanical team gets a faulty software reading or a piece of hardware that's not functioning properly, they can go back through our photos and images and diagnose the problem.
VIDEO: LEE HOBSON / JOHNS HOPKINS APPLIED PHYSICS LABORATORY
What's been your favorite experience documenting the Solar Probe?
LH: I've really enjoyed writing and editing the Solar 60 video series. I wanted to come up with a way of telling a story through the eyes of our different technicians and scientists and engineers. They get to be the reporters, and they have great camera presence, and I get to be the producer and script writer. So that's a lot of fun, getting to tell those stories. And, of course, the access that I have to the spacecraft. I mean, we're working next to the spacecraft that's going to fly within 4 million miles of the sun, and I get to walk around the launchpad. So that's really cool.
EW: For me, it's interesting to see the process of building something that's so highly engineered and thought out but is still a one-off that's never been built before. And I got to integrate my photography with the mechanical team for a test they needed to conduct: They had to lift the spacecraft way up in the sky and then drop down this magnetometer boom, and they had to do it really carefully so they could see how things were working. As it was coming down, I was walking around taking photos in 360 degrees, and I was shooting the photos to the lead engineer using my iPad. I mean, this $2 billion spacecraft is dangling from this lift in front of me and from my photos, the engineer can see the boom harness and determine the clearance and how it interacts with the spacecraft.
Engineers created a bank of lasers to test the solar arrays that will power the spacecraft. "When we turned off the lights, magical things happened," says Whitman. "Reflections and a purple glow everywhere... Visually, it was really incredible."
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What's the most surprising thing about your work with the Solar Probe?
EW: The spacecraft is so light! It's only 1,500 pounds, and it's being launched in literally the biggest launch vehicle ever built, the Delta IV Heavy. It's a monster! It stands in front of you like a building. You feel so tiny and insignificant when you look at it, and the spacecraft—they call it a hood ornament—it's this tiny thing in this giant housing, but those are the things that are going to fall away during launch. It's just mind-boggling to me.
"[The spacecraft is] being launched in literally the biggest launch vehicle ever built, the Delta IV Heavy. It's a monster! It stands in front of you like a building," says Whitman.
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How do you think you'll feel when the Parker Solar Probe finally launches?
EW: I'll feel probably sad and elated. Happy that I was part of something that's just so awesome, but sad in the sense that I don't want it to end because it's just so exciting and so interesting.
LH: I'm always really proud when we have a successful launch, and we've gotten that telemetry maybe 20 minutes after launch that means it survived and that the engineers built a really good spacecraft. But also I'll feel really proud when we start to get the data sent back. I mean, the Parker Solar Probe is going to rewrite the textbooks with new information about the sun and the corona, and I've touched it—the spacecraft that's going to fly around our sun and give scientists information that they never knew before. That's really exciting.
Quelle: Johns Hopkins University
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Update: 21.07.2018
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NASA Prepares to Launch Parker Solar Probe, a Mission to Touch the Sun
NASA's First Spacecraft to 'Touch the Sun' Ready For August 6 Launch on Delta IV Heavy
Our Sun is far more complex than meets the eye. Rather than the steady, unchanging disk it seems to human eyes, the Sun is a dynamic and magnetically active star. The Sun's atmosphere constantly sends magnetized material outward, enveloping our solar system far beyond the orbit of Pluto and influencing every world along the way. Coils of magnetic energy can burst out with light and particle radiation that travel through space and create temporary disruptions in our atmosphere, sometimes garbling radio and communications signals near Earth. The influence of solar activity on Earth and other worlds are collectively known as space weather, and the key to understanding its origins lies in understanding the Sun itself.
“The Sun’s energy is always flowing past our world,” said Fox. “And even though the solar wind is invisible, we can see it encircling the poles as the aurora, which are beautiful – but reveal the enormous amount of energy and particles that cascade into our atmosphere. We don’t have a strong understanding of the mechanisms that drive that wind toward us, and that’s what we’re heading out to discover.”
That's where Parker Solar Probe comes in. The spacecraft carries a lineup of instruments to study the Sun both remotely and in situ, or directly. Together, the data from these state-of-the-art instruments should help scientists answer three foundational questions about our star.
One of those questions is the mystery of the acceleration of the solar wind, the Sun's constant outflow of material. Though we largely grasp the solar wind's origins on the Sun, we know there is a point – as-yet unobserved – where the solar wind is accelerated to supersonic speeds. Data shows these changes happen in the corona, a region of the Sun's atmosphere that Parker Solar Probe will fly directly through, and scientists plan to use Parker Solar Probe's remote and in situ measurements to shed light on how this happens.
Second, scientists hope to learn the secret of the corona's enormously high temperatures. The visible surface of the Sun is about 10,000 F – but, for reasons we don't fully understand, the corona is hundreds of times hotter, spiking up to several million degrees F. This is counterintuitive, as the Sun's energy is produced at its core.
"It's a bit like if you walked away from a campfire and suddenly got much hotter," said Fox.
Finally, Parker Solar Probe's instruments should reveal the mechanisms at work behind the acceleration of solar energetic particles, which can reach speeds more than half as fast as the speed of light as they rocket away from the Sun. Such particles can interfere with satellite electronics, especially for satellites outside of Earth's magnetic field.
To answer these questions, Parker Solar Probe uses four suites of instruments.
The FIELDS suite, led by the University of California, Berkeley, measures the electric and magnetic fields around the spacecraft. FIELDS captures waves and turbulence in the inner heliosphere with high time resolution to understand the fields associated with waves, shocks and magnetic reconnection, a process by which magnetic field lines explosively realign.
The WISPR instrument, short for Wide-Field Imager for Parker Solar Probe, is the only imaging instrument aboard the spacecraft. WISPR takes images from of structures like coronal mass ejections, or CMEs, jets and other ejecta from the Sun to help link what’s happening in the large-scale coronal structure to the detailed physical measurements being captured directly in the near-Sun environment. WISPR is led by the Naval Research Laboratory in Washington, D.C.
Another suite, called SWEAP (short for Solar Wind Electrons Alphas and Protons Investigation), uses two complementary instruments to gather data. The SWEAP suite of instruments counts the most abundant particles in the solar wind — electrons, protons and helium ions — and measures such properties as velocity, density, and temperature to improve our understanding of the solar wind and coronal plasma. SWEAP is led by the University of Michigan, the University of California, Berkeley, and the Smithsonian Astrophysical Observatory in Cambridge, Massachusetts.
Finally, the ISʘIS suite – short for Integrated Science Investigation of the Sun, and including ʘ, the symbol for the Sun, in its acronym – measures particles across a wide range of energies. By measuring electrons, protons and ions, ISʘIS will understand the particles’ lifecycles — where they came from, how they became accelerated and how they move out from the Sun through interplanetary space. ISʘIS is led by Princeton University in New Jersey.
Parker Solar Probe is a mission some sixty years in the making. With the dawn of the Space Age, humanity was introduced to the full dimension of the Sun's powerful influence over the solar system. In 1958, physicist Eugene Parker published a groundbreaking scientific paper theorizing the existence of the solar wind. The mission is now named after him, and it's the first NASA mission to be named after a living person.
Only in the past few decades has technology come far enough to make Parker Solar Probe a reality. Key to the spacecraft's daring journey are three main breakthroughs: The cutting-edge heat shield, the solar array cooling system, and the advanced fault management system.
“The Thermal Protection System (the heat shield) is one of the spacecraft’s mission-enabling technologies,” said Andy Driesman, Parker Solar Probe project manager at the Johns Hopkins Applied Physics Lab. “It allows the spacecraft to operate at about room temperature."
Other critical innovations are the solar array cooling system and on-board fault management systems. The solar array cooling system allows the solar arrays to produce power under the intense thermal load from the Sun and the fault management system protects the spacecraft during the long periods of time when the spacecraft can’t communicate with the Earth.
Using data from seven Sun sensors placed all around the edges of the shadow cast by the heat shield, Parker Solar Probe's fault management system protects the spacecraft during the long periods of time when it can't communicate with Earth. If it detects a problem, Parker Solar Probe will self-correct its course and pointing to ensure that its scientific instruments remain cool and functioning during the long periods when the spacecraft is out of contact with Earth.
Parker Solar Probe's heat shield – called the thermal protection system, or TPS – is a sandwich of carbon-carbon composite surrounding nearly four and half inches of carbon foam, which is about 97% air. Though it's nearly eight feet in diameter, the TPS adds only about 160 pounds to Parker Solar Probe's mass because of its lightweight materials.
Though the Delta IV Heavy is one of the world’s most powerful rockets, Parker Solar Probe is relatively small, about the size of a small car. But what Parker Solar Probe needs is energy – getting to the Sun takes a lot of energy at launch to achieve its orbit around the Sun. That's because any object launched from Earth starts out traveling around the Sun at the same speed as Earth – about 18.5 miles per second – so an object has to travel incredibly quickly to counteract that momentum, change direction, and go near the Sun.
The timing of Parker Solar Probe's launch – between about 4 and 6 a.m. EDT, and within a period lasting about two weeks – was very precisely chosen to send Parker Solar Probe toward its first, vital target for achieving such an orbit: Venus.
“The launch energy to reach the Sun is 55 times that required to get to Mars, and two times that needed to get to Pluto,” said Yanping Guo from the Johns Hopkins Applied Physics Laboratory, who designed the mission trajectory. “During summer, Earth and the other planets in our solar system are in the most favorable alignment to allow us to get close to the Sun.”
The spacecraft will perform a gravity assist to shed some of its speed into Venus' well of orbital energy, drawing Parker Solar Probe into an orbit that – already, on its first pass – carries it closer to the solar surface than any spacecraft has ever gone, well within the corona. Parker Solar Probe will perform similar maneuvers six more times throughout its seven-year mission, assisting the spacecraft to final sequence of orbits that pass just over 3.8 million miles from the photosphere.
“By studying our star, we can learn not only more about the Sun,” said Thomas Zurbuchen, the associate administrator for the Science Mission Directorate at NASA HQ. “We can also learn more about all the other stars throughout the galaxy, the universe and even life’s beginnings.”
Parker Solar Probe is part of NASA’s Living with a Star Program, or LWS, to explore aspects of the Sun-Earth system that directly affect life and society. LWS is managed by NASA’s Goddard Space Flight Center in Greenbelt, Maryland, for the Heliophysics Division of NASA’s Science Mission Directorate in Washington. Johns Hopkins APL manages the Parker Solar Probe mission for NASA. APL designed and built the spacecraft and will also operate it.
Quelle: NASA
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Update: 22.07.2018
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NASA’s Parker Solar Probe will ‘shake’ hands with sun, thanks to small push from Venus
Sending a spacecraft from Earth to a stationary target like the sun is like trying to throw a dart from a speeding train. That’s because Earth is barreling through space at 19 miles per second, or 67,000 miles per hour. No matter how fast we try to shoot the probe into space, its momentum will cause it to keep orbiting the sun.
In early August, NASA will take on this challenge when it launches the Parker Solar Probe — a mission to fly seven times closer to the sun than any other spacecraft has before.
Like Icarus of Greek mythology, the journey is a daring flight into the unknown. But NASA scientists must strike the perfect balance between flying just close enough that the spacecraft can collect the data it needs but not so close that it burns up. Here’s what the mission will take.
The Venus effect
Yanping Guo is the mission designer for the probe. She has worked for the past 16 years to create a flight path for the mission at the Johns Hopkins University Applied Physics Laboratory, where the probe was designed and built.
Yanping Guo is the mission designer for the Parker Solar Probe. She and her team have mapped a journey that will bring the probe into the sun’s corona. Photo by Johns Hopkins APL/Ed Whitman
“You might think getting to the sun is easy because it’s not far and you can see it,” she said. “But of all the solar system explorations, it’s the most challenging.”
The only way to get it close, Guo figures, is to slow the Parker Solar Probe way down, so it can achieve tighter orbits around the sun. To do that, the 1,400-pound probe will get a little help from Venus. The probe will fly just close enough to Venus so that it will get pulled toward the surface, allowing it to slow down and change its path–this is called a gravity assist.
Over the next seven years, as it circles the sun, the probe will wrap around Venus seven times, each time slowing down and swooping closer to the sun. In seven years, the probe will be within four million miles of the sun’s surface. In space terms, that’s practically shaking hands.
Guo has employed this tactic of using other planets to help move spaceships in the past. For instance, she used Jupiter to propel the New Horizons mission to Pluto. But using the same planet seven times? That’s completely new, and there’s a lot to keep track of.
“To achieve the flyby, you have to know how fast you’re moving, where the orbit is, where Venus is,” Guo said. “You have to have it all sorted out, predicted precisely, and timed exactly to be in the right place at the right time.”
Every inch closer to the sun means the probe will be exposed to more excruciating heat and radiation. At its closest pass, in December 2024, the probe will be subjected to 2,500 degrees Fahrenheit — which is toasty but still pales in comparison to solar flares that reach tens of millions of degrees. The probe will be flying straight through coronal plasma, which is electrified gas that shoots out from the sun’s surface, hoping to miss these super hot flares. (Don’t worry, the chances of hitting a flare are low.)
Thanks to a state-of-the-art carbon-carbon heat shield, the Parker Solar Probe’s instruments will be kept at room temperature if everything goes as planned.
“Whatever we think the worst case could possibly be, we are designed and built to withstand a lot worse than that,” said Nicola Fox, project scientist for the probe mission, also at Johns Hopkins.
The probe, including its carbon-carbon heat shield, is only about 10 feet tall. Its light weight and small stature make it easier to shoot into space. Photo by NASA/Johns Hopkins APL/Ed Whitman
What Parker is probing
After all, getting close to the sun is the whole point. The probe will take scientists into the solar corona–the sun’s atmosphere. Nicholeen Viall is a solar scientist at NASA who is anxiously awaiting data from the probe to answer questions that have eluded scientists for years.
One thing on Viall’s mind is what she calls the counterintuitive “coronal heating problem,” a phenomenon in which the sun’s atmosphere is hundreds of times hotter than the sun’s surface. That’s like walking away from a normal fireplace and suddenly being subjected to 100,000 degree temperatures.
Scientists know that the phenomenon has something to do with the interaction between the sun’s heat and magnetic waves, but no one knows exactly what is happening.
Illustration of the Parker Solar Probe spacecraft approaching the Sun. Image by NASA/Johns Hopkins APL/Steve Gribben
“With the probe, we get to stick a thermometer and a magnetic field sensor into the sun right as these very energetic processes happen,” said Viall, who wasn’t involved with the mission. “These are new measurements we’ve never been able to make before.”
A close look at the sun’s magnetic field will also shine light on the origins of solar wind–that’s the charged gas that comes off the sun and bombards Earth. Our planet’s magnetic field wards off this radiation.
Quelle: PBS
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Update: 24.07.2018
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Quelle: NASA
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Update: 25.07.2018
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Parker Solar Probe Launch Targeted for Aug. 11
NASA and its mission partners are targeting Aug. 11 for the launch of the Parker Solar Probe mission to the Sun. The 45-minute launch window will open at 3:48 a.m. EDT. During final inspections following the encapsulation of the spacecraft, a small strip of foam was found inside the fairing and additional time is needed for inspection.
The spacecraft will launch on a United Launch Alliance Delta IV Heavy rocket from Space Launch Complex 37 on Cape Canaveral Air Force Station in Florida.
Quelle: NASA
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