Pi Guides The Way

Pi Guides the Way

It may be irrational but pi plays an important role in the everyday work of scientists at NASA. 

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What Is Pi ?

Pi is the ratio of a circle’s circumference to its diameter. It is also an irrational number, meaning its decimal representation never ends and it never repeats. Pi has been calculated to more than one trillion digits, 

Why March 14?

March 14 marks the yearly celebration of the mathematical constant pi. More than just a number for mathematicians, pi has all sorts of applications in the real world, including on our missions. And as a holiday that encourages more than a little creativity – whether it’s making pi-themed pies or reciting from memory as many of the never-ending decimals of pi as possible (the record is 70,030 digits).

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While 3.14 is often a precise enough approximation, hence the celebration occurring on March 14, or 3/14 (when written in standard U.S.  month/day format), the first known celebration occurred in 1988, and in 2009, the U.S. House of Representatives passed a resolution designating March 14 as Pi Day and encouraging teachers and students to celebrate the day with activities that teach students about pi.

5 Ways We Use Pi at NASA

Below are some ways scientists and engineers used pi.

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Keeping Spacecraft Chugging Along

Propulsion engineers use pi to determine the volume and surface area of propellant tanks. It’s how they size tanks and determine liquid propellant volume to keep spacecraft going and making new discoveries. 

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Getting New Perspectives on Saturn

A technique called pi transfer uses the gravity of Titan’s moon, Titan, to alter the orbit of the Cassini spacecraft so it can obtain different perspectives of the ringed planet.

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Learning the Composition of Asteroids

Using pi and the asteroid’s mass, scientists can calculate the density of an asteroid and learn what it’s made of--ice, iron, rock, etc.

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Measuring Craters

knowing the circumference, diameter and surface area of a crater can tell scientists a lot about the asteroid or meteor that may have carved it out.

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Determining the Size of Exoplanets

Exoplanets are planets that orbit suns other than our own and scientists use pi to search for them. The first step is determining how much the light curve of a planet’s sun dims when a suspected planets passes in front of it.

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More Posts from Nasa and Others

2 years ago

A Dusty Fingerprint in Space

An image from NASA’s James Webb Space Telescope shows a bright dot at the center of star-filled black space. The bright dot is actually two stars meeting, as their orbits bring them together every 8 years. The stellar pair are surrounded by 17 rings of gas and dust that appear orangish gray. The rings have a slight rectangular shape and are very clear and defined starting at about 1 o’clock on a clockface. The rings start to break up a bit to our view traveling clockwise around the image. As you arrive at the 12:40 position, only parts of about six rings can be seen as they disappear from view.

A new image from NASA's James Webb Space Telescope reveals a remarkable cosmic sight: at least 17 concentric dust rings emanating from a pair of stars. Just 5,300 light-years from Earth, the star duo are collectively known as Wolf-Rayet 140. Each ring was created when the two stars came close together and their stellar winds (streams of gas they blow into space) collided so forcefully that some of the gas was compressed into dust. The stars' orbits bring them together about once every eight years, and forms a half-shell of dust that looks like a ring from our perspective. Like a cosmic fingerprint, the 17 rings reveal more than a century of stellar interactions—and the "fingerprint" belonging to Wolf-Rayet 140 may be equally unique. Other Wolf-Rayet stars produce dust, but no other pair are known to produce rings quite like Wolf-Rayet 140.

Learn more about Wolf-Rayet 140.

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9 years ago

Answer Time with NASA Astronaut Peggy Whitson

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Ever wonder what it’s like to be a NASA astronaut? On Thursday, Oct. 29, NASA Astronaut Peggy Whitson will answer your questions! She’ll explain how it takes the NASA Village to help train for her mission to space, what the challenges of living in space are and what it’s like to be a NASA astronaut.

Enter your questions here. The Answer Time begins at 3 p.m. EDT on Thursday, Oct. 29.

Fun facts about NASA Astronaut Peggy Whitson:

Astronaut Whitson was selected as an Astronaut Candidate in April 1996, and started training in August of the same year.

After completing two years of training and evaluation, she served as the lead for the Crew Test Support Team in Russia from 1998 to 1999.

Astronaut Whitson completed two six-month tours of duty aboard the International Space Station.

She has accumulated 377 days in space between two missions, which is the most for any woman.

Astronaut Whitson has performed a total of six career spacewalks, adding up to 39 hours and 46 minutes! She is also one of only a handful of people to perform spacewalks in both Russian and US spacesuits.

She is scheduled to launch in late 2016 as part of the Expedition 50/51.

Firsts:

Science Officer of the International Space Station

Female Commander for the International Space Station

Female to serve as Chief of the Astronaut Office

Follow her on social media to see how it takes a NASA Village to train her for her upcoming mission: Tumblr, Facebook and Twitter. 


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5 years ago

How Gravity Warps Light

Gravity is obviously pretty important. It holds your feet down to Earth so you don’t fly away into space, and (equally important) it keeps your ice cream from floating right out of your cone! We’ve learned a lot about gravity over the past few hundred years, but one of the strangest things we’ve discovered is that most of the gravity in the universe comes from an invisible source called “dark matter.” While our telescopes can’t directly see dark matter, they can help us figure out more about it thanks to a phenomenon called gravitational lensing.

The Gravity of the Situation

Anything that has mass is called matter, and all matter has gravity. Gravity pulls on everything that has mass and warps space-time, the underlying fabric of the universe. Things like llamas and doughnuts and even paper clips all warp space-time, but only a tiny bit since they aren’t very massive.

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But huge clusters of galaxies are so massive that their gravity produces some pretty bizarre effects. Light always travels in a straight line, but sometimes its path is bent. When light passes close to a massive object, space-time is so warped that it curves the path the light must follow. Light that would normally be blocked by the galaxy cluster is bent around it, producing intensified — and sometimes multiple — images of the source. This process, called gravitational lensing, turns galaxy clusters into gigantic, intergalactic magnifying glasses that give us a glimpse of cosmic objects that would normally be too distant and faint for even our biggest telescopes to see.

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Hubble “Sees” Dark Matter

Let’s recap — matter warps space-time. The more matter, the stronger the warp and the bigger its gravitational lensing effects. In fact, by studying “lensed” objects, we can map out the quantity and location of the unseen matter causing the distortion!

Thanks to gravitational lensing, scientists have measured the total mass of many galaxy clusters, which revealed that all the matter they can see isn’t enough to create the warping effects they observe. There’s more gravitational pull than there is visible stuff to do the pulling — a lot more! Scientists think dark matter accounts for this difference. It’s invisible to our eyes and telescopes, but it can’t hide its gravity!

The mismatch between what we see and what we know must be there may seem strange, but it’s not hard to imagine. You know that people can’t float in mid-air, so what if you saw a person appearing to do just that? You would know right away that there must be wires holding him up, even if you couldn’t see them.

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Our Hubble Space Telescope observations are helping unravel the dark matter mystery. By studying gravitationally lensed galaxy clusters with Hubble, astronomers have figured out how much of the matter in the universe is “normal” and how much is “dark.” Even though normal matter makes up everything from pickles to planets, there’s about five times more dark matter in the universe than all the normal matter combined!

WFIRST Will Escalate the Search

One of our next major space telescopes, the Wide Field Infrared Survey Telescope (WFIRST), will take these gravitational lensing observations to the next level. WFIRST will be sensitive enough to use weak gravitational lensing to see how clumps of dark matter warp the appearance of distant galaxies. By observing lensing effects on this small scale, scientists will be able to fill in more of the gaps in our understanding of dark matter.

WFIRST will observe a sky area 100 times larger than Hubble does, but with the same awesome image quality. WFIRST will collect so much data in its first year that it will allow scientists to conduct in-depth studies that would have taken hundreds of years with previous telescopes.

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WFIRST’s weak gravitational lensing observations will allow us to peer even further back in time than Hubble is capable of seeing. Scientists believe that the universe’s underlying dark matter structure played a major role in the formation and evolution of galaxies by attracting normal matter. Seeing the universe in its early stages will help scientists unravel how it has evolved over time and possibly provide clues to how it may continue to evolve. We don’t know what the future will hold, but WFIRST will help us find out.

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This science is pretty mind-bending, even for scientists. Learn more as our current and future telescopes plan to help unlock these mysteries of the universe...

Hubble: https://www.nasa.gov/mission_pages/hubble/main/index.html WFIRST: https://wfirst.gsfc.nasa.gov/

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7 years ago

The Sun Just Released the Most Powerful Flare of this Solar Cycle

The Sun released two significant solar flares on Sept. 6, including one that clocked in as the most powerful flare of the current solar cycle.

The solar cycle is the approximately 11-year-cycle during which the Sun’s activity waxes and wanes. The current solar cycle began in December 2008 and is now decreasing in intensity and heading toward solar minimum, expected in 2019-2020. Solar minimum is a phase when solar eruptions are increasingly rare, but history has shown that they can nonetheless be intense.

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Footage of the Sept. 6 X2.2 and X9.3 solar flares captured by the Solar Dynamics Observatory in extreme ultraviolet light (131 angstrom wavelength)

Our Solar Dynamics Observatory satellite, which watches the Sun constantly, captured images of both X-class flares on Sept. 6.

Solar flares are classified according to their strength. X-class denotes the most intense flares, followed by M-class, while the smallest flares are labeled as A-class (near background levels) with two more levels in between. Similar to the Richter scale for earthquakes, each of the five levels of letters represents a 10-fold increase in energy output. 

The first flare peaked at 5:10 a.m. EDT, while the second, larger flare, peaked at 8:02 a.m. EDT.

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Footage of the Sept. 6 X2.2 and X9.3 solar flares captured by the Solar Dynamics Observatory in extreme ultraviolet light (171 angstrom wavelength) with Earth for scale

Solar flares are powerful bursts of radiation. Harmful radiation from a flare cannot pass through Earth's atmosphere to physically affect humans on the ground, however — when intense enough — they can disturb Earth’s atmosphere in the layer where GPS and communications signals travel.

Both Sept. 6 flares erupted from an active region labeled AR 2673. This area also produced a mid-level solar flare on Sept. 4, 2017. This flare peaked at 4:33 p.m. EDT, and was about a tenth the strength of X-class flares like those measured on Sept. 6.

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Footage of the Sept. 4 M5.5 solar flare captured by the Solar Dynamics Observatory in extreme ultraviolet light (131 angstrom wavelength)

This active region continues to produce significant solar flares. There were two flares on the morning of Sept. 7 as well. 

For the latest updates and to see how these events may affect Earth, please visit NOAA’s Space Weather Prediction Center at http://spaceweather.gov, the U.S. government’s official source for space weather forecasts, alerts, watches and warnings.

Follow @NASASun on Twitter and NASA Sun Science on Facebook to keep up with all the latest in space weather research.

Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com.


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6 years ago

Happy 4th of July… From Space!

In Hollywood blockbusters, explosions and eruptions are often among the stars of the show. In space, explosions, eruptions and twinkling of actual stars are a focus for scientists who hope to better understand their births, lives, deaths and how they interact with their surroundings. Spend some of your Fourth of July taking a look at these celestial phenomenon:

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Credit: NASA/Chandra X-ray Observatory

An Astral Exhibition

This object became a sensation in the astronomical community when a team of researchers pointed at it with our Chandra X-ray Observatory telescope in 1901, noting that it suddenly appeared as one of the brightest stars in the sky for a few days, before gradually fading away in brightness. Today, astronomers cite it as an example of a “classical nova,” an outburst produced by a thermonuclear explosion on the surface of a white dwarf star, the dense remnant of a Sun-like star.

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Credit: NASA/Hubble Space Telescope

A Twinkling Tapestry

The brilliant tapestry of young stars flaring to life resemble a glittering fireworks display. The sparkling centerpiece is a giant cluster of about 3,000 stars called Westerlund 2, named for Swedish astronomer Bengt Westerlund who discovered the grouping in the 1960s. The cluster resides in a raucous stellar breeding ground located 20,000 light-years away from Earth in the constellation Carina.

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Credit: NASA/THEMIS/Sebastian Saarloos

An Illuminating Aurora

Sometimes during solar magnetic events, solar explosions hurl clouds of magnetized particles into space. Traveling more than a million miles per hour, these coronal mass ejections, or CMEs, made up of hot material called plasma take up to three days to reach Earth. Spacecraft and satellites in the path of CMEs can experience glitches as these plasma clouds pass by. In near-Earth space, magnetic reconnection incites explosions of energy driving charged solar particles to collide with atoms in Earth’s upper atmosphere. We see these collisions near Earth’s polar regions as the aurora. Three spacecraft from our Time History of Events and Macroscale Interactions during Substorms (THEMIS) mission, observed these outbursts known as substorms.

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Credit: NASA/Hubble Space Telescope//ESA/STScI

A Shining Supermassive Merger

Every galaxy has a black hole at its center. Usually they are quiet, without gas accretions, like the one in our Milky Way. But if a star creeps too close to the black hole, the gravitational tides can rip away the star’s gaseous matter. Like water spinning around a drain, the gas swirls into a disk around the black hole at such speeds that it heats to millions of degrees. As an inner ring of gas spins into the black hole, gas particles shoot outward from the black hole’s polar regions. Like bullets shot from a rifle, they zoom through the jets at velocities close to the speed of light. Astronomers using our Hubble Space Telescope observed correlations between supermassive black holes and an event similar to tidal disruption, pictured above in the Centaurus A galaxy. 

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Credit: NASA/Hubble Space Telescope/ESA

A Stellar Explosion

Supernovae can occur one of two ways. The first occurs when a white dwarf—the remains of a dead star—passes so close to a living star that its matter leaks into the white dwarf. This causes a catastrophic explosion. However most people understand supernovae as the death of a massive star. When the star runs out of fuel toward the end of its life, the gravity at its heart sucks the surrounding mass into its center. At the turn of the 19th century, the binary star system Eta Carinae was faint and undistinguished. Our Hubble Telescope captured this image of Eta Carinae, binary star system. The larger of the two stars in the Eta Carinae system is a huge and unstable star that is nearing the end of its life, and the event that the 19th century astronomers observed was a stellar near-death experience. Scientists call these outbursts supernova impostor events, because they appear similar to supernovae but stop just short of destroying their star.

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Credit: NASA/GSFC/SDO

An Eye-Catching Eruption

Extremely energetic objects permeate the universe. But close to home, the Sun produces its own dazzling lightshow, producing the largest explosions in our solar system and driving powerful solar storms.. When solar activity contorts and realigns the Sun’s magnetic fields, vast amounts of energy can be driven into space. This phenomenon can create a sudden flash of light—a solar flare.The above picture features a filament eruption on the Sun, accompanied by solar flares captured by our Solar Dynamics Observatory.

Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com


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4 years ago

That's a wrap! Thank you all for the wonderful questions.

NASA Mars Perseverance Rover Mission Engineer Chloe Sackier answered questions about how we prepared for the mission, Perseverance’s entry, descent, and landing, and what Perseverance will do once on Mars.

Check out her full Answer Time for more: Career | Preparation | Entry, Descent, & Landing | Operation

We hope you had fun today and learned a little bit about our robotic astrobiologist landing on Mars on February 18th. You won't want to miss this! Tune in to NASA TV HERE starting at 2:15 p.m. EST.

That's A Wrap! Thank You All For The Wonderful Questions.

If today’s Answer Time got you excited, team up with us to #CoutdownToMars! We created a virtual Mars photo booth, have sounds of Mars to listen to and more for all you Earthlings to channel your inner Martian. Check out ways to participate HERE.

Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com


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8 years ago

Physical Science...In Space!

Each month, we highlight a different research topic on the International Space Station. In May, our focus is physical science.

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The space station is a laboratory unlike any on Earth; on-board, we can control gravity as a variable and even remove it entirely from the equation. Removing gravity reveals fundamental aspects of physics hidden by force-dependent phenomena such as buoyancy-driven convection and sedimentation.

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Gravity often masks or distorts subtle forces such as surface tension and diffusion; on space station, these forces have been harnessed for a wide variety of physical science applications (combustion, fluids, colloids, surface wetting, boiling, convection, materials processing, etc).

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Other examples of observations in space include boiling in which bubbles do not rise, colloidal systems containing crystalline structures unlike any seen on Earth and spherical flames burning around fuel droplets. Also observed was a uniform dispersion of tin particles in a liquid melt, instead of rising to the top as would happen in Earth’s gravity. 

Physical Science...In Space!

So what? By understanding the fundamentals of combustion and surface tension, we may make more efficient combustion engines; better portable medical diagnostics; stronger, lighter alloys; medicines with longer shelf-life, and buildings that are more resistant to earthquakes.

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Findings from physical science research on station may improve the understanding of material properties. This information could potentially revolutionize development of new and improved products for use in everything from automobiles to airplanes to spacecraft.

For more information on space station research, follow @ISS_Research on Twitter!

Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com


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6 years ago

NASA’s 60th Anniversary: How It All Began

Congress passed the National Aeronautics and Space Act, on July 16 and President Eisenhower signed it into law on July 29, 1958. We opened for business on Oct. 1, 1958, with T. Keith Glennan as our first administrator. Our history since then tells a story of exploration, innovation and discoveries. The next 60 years, that story continues. Learn more: https://www.nasa.gov/60

Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com.


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7 years ago

A Hitchhiker’s Ride to Space

This month, we are set to launch the latest weather satellite from the National Oceanic and Atmospheric Administration (NOAA). The Joint Polar Satellite System-1, or JPSS-1, satellite will provide essential data for timely and accurate weather forecasts and for tracking environmental events such as forest fires and droughts.

A Hitchhiker’s Ride To Space
8 years ago

6 Reasons NOAA’s GOES-R Satellite Matters

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NOAA’s GOES-R weather satellite will soon be launched into space – becoming our nation’s most advanced geostationary satellite to date. So what does that mean for you? Here are six reasons to be excited about GOES-R:

1. GOES-R helps you know what the weather is going to be

Perhaps you turn on the TV or radio, or check your favorite weather website or smartphone weather app to get the latest forecast. No matter the platform of your weather forecast, the data and information for those forecasts come from NOAA’s National Weather Service (NWS).

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Weather satellites, like the GOES satellites, are the backbone of NWS forecasts. GOES-R will be more advanced than any other weather satellite of its kind and could make the answer to the question “What’s the weather going to be?” more detailed and accurate both in the near term and further out into the future.

2. GOES-R will get better data faster than ever before

Do you live in an inland state, a state with a coastline or a state with a mountain range? Great, that’s all of you! Data from the GOES-R satellite will be a game changer for forecasters in your area.

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Here’s why: satellites are fitted with instruments that observe weather and collect measurements. The primary instrument on the new GOES-R satellite will collect three times more data and provide four times better resolution and more than five times faster coverage than current satellites! This means the satellite can scan Earth’s Western Hemisphere every five minutes and as often as every 30 seconds in areas where severe weather forms, as compared to approximately every 30 minutes with the current GOES satellites. Pretty cool, right?

3. GOES-R is a real life-saver

This expedited data means that forecasts will be timelier, with more “real-time” information in them, allowing NWS to make those warnings and alerts that much faster, thereby potentially saving lives.

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And a faster forecast is a big deal for our economy. Commercial shipping and aviation are just two examples of industries that rely on up-to-date weather data for critical decisions about how to route ships and safely divert planes around storms.

4. GOES-R helps keep the electricity flowing

We all depend on a power grid for virtually every aspect of modern life. But power grids are vulnerable to bursts of energy from the sun that can affect us on Earth. 

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Luckily, GOES-R will be sitting over 22,000 miles above us, and in addition to measuring weather on Earth, it will monitor incoming space weather.

5. GOES-R is truly revolutionary

How different will GOES-R be? Imagine going from your classic black and white TV to a new high definition one. It will enable NOAA to gather data using three times more channels, four times the resolution, five times faster than the current GOES satellites. 

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This faster, more accurate data means better observations of developing storms and other severe weather.

6. GOES-R will be a continuing a legacy

GOES-R may be the first of its kind, but it is the heir to a rich tradition of geostationary earth observation. 

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In fact, NOAA has continuously operated a GOES satellite for over 40 years. Since 1975, GOES satellites have taken well over 3 million images!

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The GOES-R satellite is scheduled to launch Saturday, Nov. 19 at 5:42 p.m. EST aboard a United Launch Alliance Atlas V rocket. Liftoff will occur from our Kennedy Space Center in Florida.

Learn more about the mission: https://www.nesdis.noaa.gov/GOES-R-Mission

Article Credit: NOAA

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