10 Things to Know About Parker Solar Probe

On Aug. 12, 2018, we launched Parker Solar Probe to the Sun, where it will fly closer than any spacecraft before and uncover new secrets about our star. Here’s what you need to know.

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1. Getting to the Sun takes a lot of power

At about 1,400 pounds, Parker Solar Probe is relatively light for a spacecraft, but it launched to space aboard one of the most powerful rockets in the world, the United Launch Alliance Delta IV Heavy. That’s because it takes a lot of energy to go to the Sun — in fact, 55 times more energy than it takes to go to Mars.

Any object launched from Earth starts out traveling at about the same speed and in the same direction as Earth — 67,000 mph sideways. To get close to the Sun, Parker Solar Probe has to shed much of that sideways speed, and a strong launch is good start.

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2. First stop: Venus!

Parker Solar Probe is headed for the Sun, but it’s flying by Venus along the way. This isn’t to see the sights — Parker will perform a gravity assist at Venus to help draw its orbit closer to the Sun. Unlike most gravity assists, Parker will actually slow down, giving some orbital energy to Venus, so that it can swing closer to the Sun.

One’s not enough, though. Parker Solar Probe will perform similar maneuvers six more times throughout its seven-year mission!

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3. Closer to the Sun than ever before

At its closest approach toward the end of its seven-year prime mission, Parker Solar Probe will swoop within 3.83 million miles of the solar surface. That may sound pretty far, but think of it this way: If you put Earth and the Sun on opposite ends of an American football field, Parker Solar Probe would get within four yards of the Sun’s end zone. The current record-holder was a spacecraft called Helios 2, which came within 27 million miles, or about the 30 yard line. Mercury orbits at about 36 million miles from the Sun.

This will place Parker well within the Sun’s corona, a dynamic part of its atmosphere that scientists think holds the keys to understanding much of the Sun’s activity.

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4. Faster than any human-made object

Parker Solar Probe will also break the record for the fastest spacecraft in history. On its final orbits, closest to the Sun, the spacecraft will reach speeds up to 430,000 mph. That’s fast enough to travel from New York to Tokyo in less than a minute!

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5. Dr. Eugene Parker, mission namesake

Parker Solar Probe is named for Dr. Eugene Parker, the first person to predict the existence of the solar wind. In 1958, Parker developed a theory showing how the Sun’s hot corona — by then known to be millions of degrees Fahrenheit — is so hot that it overcomes the Sun’s gravity. According to the theory, the material in the corona expands continuously outwards in all directions, forming a solar wind.

This is the first NASA mission to be named for a living person, and Dr. Parker watched the launch with the mission team from Kennedy Space Center in Florida.

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6. Unlocking the secrets of the solar wind

Even though Dr. Parker predicted the existence of the solar wind 60 years ago, there’s a lot about it we still don’t understand. We know now that the solar wind comes in two distinct streams, fast and slow. We’ve identified the source of the fast solar wind, but the slow solar wind is a bigger mystery.

Right now, our only measurements of the solar wind happen near Earth, after it has had tens of millions of miles to blur together, cool down and intermix. Parker’s measurements of the solar wind, just a few million miles from the Sun’s surface, will reveal new details that should help shed light on the processes that send it speeding out into space.

7. Studying near-light speed particles

Another question we hope to answer with Parker Solar Probe is how some particles can accelerate away from the Sun at mind-boggling speeds — more than half the speed of light, or upwards of 90,000 miles per second. These particles move so fast that they can reach Earth in under half an hour, so they can interfere with electronics on board satellites with very little warning.

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8. The mystery of the corona’s high heat

The third big question we hope to answer with this mission is something scientists call the coronal heating problem. Temperatures in the Sun’s corona, where Parker Solar Probe will fly, spike upwards of 2 million degrees Fahrenheit, while the Sun’s surface below simmers at a balmy 10,000 F. How the corona gets so much hotter than the surface remains one of the greatest unanswered questions in astrophysics.

Though scientists have been working on this problem for decades with measurements taken from afar, we hope measurements from within the corona itself will help us solve the coronal heating problem once and for all.

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9. Why won’t Parker Solar Probe melt?

The corona reaches millions of degrees Fahrenheit, so how can we send a spacecraft there without it melting?

The key lies in the distinction between heat and temperature. Temperature measures how fast particles are moving, while heat is the total amount of energy that they transfer. The corona is incredibly thin, and there are very few particles there to transfer energy — so while the particles are moving fast (high temperature), they don’t actually transfer much energy to the spacecraft (low heat).

It’s like 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 air of the oven, your hand doesn’t get nearly as hot as it would in the much denser water of the boiling pot.

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10. Engineered to thrive in an extreme environment

Make no mistake, the environment in the Sun’s atmosphere is extreme — hot, awash in radiation, and very far from home — but Parker Solar Probe is engineered to survive.

The spacecraft is outfitted with a cutting-edge heat shield made of a carbon composite foam sandwiched between two carbon plates. The heat shield is so good at its job that, even though the front side will receive the full brunt of the Sun’s intense light, reaching 2,500 F, the instruments behind it, in its shadow, will remain at a cozy 85 F.

Even though Parker Solar Probe’s solar panels — which provide the spacecraft’s power — are retractable, even the small bit of surface area that peeks out near the Sun is enough to make them prone to overheating. So, to keep its cool, Parker Solar Probe circulates a single gallon of water through the solar arrays. The water absorbs heat as it passes behind the arrays, then radiates that heat out into space as it flows into the spacecraft’s radiator.

For much of its journey, Parker Solar Probe will be too far from home and too close to the Sun for us to command it in real time — but don’t worry, Parker Solar Probe can think on its feet. Along the edges of the heat shield’s shadow are seven sensors. 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 behind the heat shield.

Read the web version of this week’s “Solar System: 10 Things to Know” article HERE.

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Spilling the Sun’s Secrets

You might think you know the Sun: It looks quiet and unchanging. But the Sun has secrets that scientists have been trying to figure out for decades.  

One of our new missions — Parker Solar Probe — is aiming to spill the Sun’s secrets and shed new light on our neighbor in the sky.

Even though it’s 93 million miles away, the Sun is our nearest and best laboratory for understanding the inner workings of stars everywhere. We’ve been spying on the Sun with a fleet of satellites for decades, but we’ve never gotten a close-up of our nearest star.

This summer, Parker Solar Probe is launching into an orbit that will take it far closer to the Sun than any instrument has ever gone. It will fly close enough to touch the Sun, sweeping through the outer atmosphere — the corona — 4 million miles above the surface.

This unique viewpoint will do a lot more than provide gossip on the Sun. Scientists will take measurements to help us understand the Sun’s secrets — including those that can affect Earth.

Parker Solar Probe is equipped with four suites of instruments that will take detailed measurements from within the Sun’s corona, all protected by a special heat shield to keep them safe and cool in the Sun’s ferocious heat.

The corona itself is home to one of the Sun’s biggest secrets: The corona’s mysteriously high temperatures. The corona, a region of the Sun’s outer atmosphere, is hundreds of times hotter than the surface below. That’s counterintuitive, like if you got warmer the farther you walked from a campfire, but scientists don’t yet know why that’s the case.

Some think the excess heat is delivered by electromagnetic waves called Alfvén waves moving outwards from the Sun’s surface. Others think it might be due to nanoflares — bomb-like explosions that occur on the Sun’s surface, similar to the flares we can see with telescopes from Earth, but smaller and much more frequent. Either way, Parker Solar Probe’s measurements direct from this region itself should help us pin down what’s really going on.

We also want to find out what exactly accelerates the solar wind — the Sun’s constant outpouring of material that rushes out at a million miles per hour and fills the Solar System far past the orbit of Pluto. The solar wind can cause space weather when it reaches Earth — triggering things like the aurora, satellite problems, and even, in rare cases, power outages.

We know where the solar wind comes from, and that it gains its speed somewhere in the corona, but the exact mechanism of that acceleration is a mystery. By sampling particles directly at the scene of the crime, scientists hope Parker Solar Probe can help crack this case.

Parker Solar Probe should also help us uncover the secrets of some of the fastest particles from the Sun. Solar energetic particles can reach speeds of more than 50% the speed of light, and they can interfere with satellites with little warning because of how fast they move. We don’t know how they get so fast — but it’s another mystery that should be solved with Parker Solar Probe on the case.  

Parker Solar Probe launches summer 2018 on a seven-year mission to touch the Sun. Keep up with the latest on the Sun at @NASASun on Twitter, and follow along with Parker Solar Probe’s last steps to launch at nasa.gov/solarprobe.

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In Conversation with the Sun: Parker Solar Probe Communications

Our Sun powers life on Earth. It defines our days, nourishes our
crops and even fuels our electrical grids. In our pursuit of knowledge
about the universe, we’ve learned so much about the Sun, but in many ways we’re
still in conversation with it, curious about its mysteries.

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Parker Solar
Probe
will advance this conversation, flying
through the Sun’s atmosphere as close as 3.8 million miles from our star’s
surface, more than seven times closer to it than any previous spacecraft. If
space were a football field, with Earth at one end and the Sun at the other,
Parker would be at the four-yard line, just steps away from the Sun! This
journey will revolutionize our understanding of the Sun, its surface and solar
winds.

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Supporting Parker on its journey to the
Sun are our communications networks. Three networks, the Near Earth Network,
the Space
Network
and the Deep Space Network, provide our
spacecraft with their communications, delivering their data to mission
operations centers. Their services ensure that missions like Parker have
communications support from launch through the mission.

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For Parker’s launch
on Aug. 12, the Delta IV Heavy rocket that sent Parker skyward relied on the Space
Network. A team at Goddard Space Flight Center’s Networks Integration Center
monitored the launch, ensuring that we maintained tracking and communications
data between the rocket and the ground. This data is vital, allowing engineers
to make certain that Parker stays on the right path towards its orbit around
the Sun.

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The Space Network’s constellation of Tracking and Data
Relay Satellites
(TDRS) enabled constant communications coverage for
the rocket as Parker made its way out of Earth’s atmosphere. These satellites
fly in geosynchronous orbit, circling Earth in step with its rotation, relaying
data from spacecraft at lower altitudes to the ground. The network’s three collections
of TDRS over the Atlantic, Pacific and Indian oceans provide enough coverage
for continuous communications for satellites in low-Earth orbit.

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The Near Earth Network’s Launch
Communications Segment tracked early stages of Parker’s launch, testing our brand
new ground stations’ ability to provide crucial information about the rocket’s
initial velocity (speed) and trajectory (path). When fully operational, it will
support launches from the Kennedy spaceport, including upcoming Orion
missions. The Launch Communications Segment’s three ground stations are located
at Kennedy Space Center; Ponce De Leon, Florida; and Bermuda. 

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When Parker separated from the Delta IV
Heavy, the Deep Space Network took over. Antennas up to 230 feet in diameter at
ground stations in California, Australia and Spain are supporting Parker for
its 24 orbits around the Sun and the seven Venus flybys that gradually shrink
its orbit, bringing it closer and closer to the Sun. The Deep Space Network is
delivering data to mission operations centers and will continue to do so as
long as Parker is operational.

Near the
Sun, radio interference and the heat load on the spacecraft’s antenna makes
communicating with Parker a challenge that we must plan for. Parker has three
distinct communications phases, each corresponding to a different part of its
orbit.

When Parker comes closest to the Sun, the
spacecraft will emit a beacon tone that tells engineers on the ground about its
health and status, but there will be very little opportunity to command the
spacecraft and downlink data. High data rate transmission will only occur
during a portion of Parker’s orbit, far from the Sun. The rest of the time,
Parker will be in cruise mode, taking measurements and being commanded through
a low data rate connection with Earth.

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Communications infrastructure is vital to
any mission. As Parker journeys ever closer to the center of our solar system,
each byte of downlinked data will provide new insight into our Sun. It’s a
mission that continues a conversation between us and our star that has lasted many
millions of years and will continue for many millions more.

For more information about NASA’s mission
to touch the Sun: https://www.nasa.gov/content/goddard/parker-solar-probe

For more information about our satellite
communications check out: http://nasa.gov/SCaN


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