@dasandwichguy: What Precautions Do You Take To Curb The Effects Of Weightlessness?

Is there a pot of gold at the end of a green aurora? Not sure, but these dancing green lights provide a spectacular view fitting for the St. Patrick’s Day holiday. 

This stunning aurora was captured by NASA astronaut Jeff Williams during his 2016 mission on the International Space Station. 

Even though auroras are best seen at night, they are actually caused by the sun. The sun sends us more than just heat a light…it sends lots of other energy and small particles toward Earth. The protective magnetic field around Earth shields us from most of the energy and particles. Sometimes, the particles interact with gases in our atmosphere resulting in beautiful displays of light in the sky. Oxygen gives off green and red light, while nitrogen glows blue and purple.

Happy St. Patrick’s Day!

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Did somebody say space laser?

We’re set to launch ICESat-2, our most advanced laser instrument of its kind, into orbit around Earth on Sept. 15. The Ice, Cloud and land Elevation Satellite-2 will make critical observations of how ice sheets, glaciers and sea ice are changing over time, helping us better understand how those changes affect people where they live. Here’s 10 numbers to know about this mission:

One Space Laser

There’s only one scientific instrument on ICESat-2, but it’s a marvel. The Advanced Topographic Laser Altimeter System, or ATLAS, measures height by precisely timing how long it takes individual photons of light from a laser to leave the satellite, bounce off Earth, and return to ICESat-2. Hundreds of people at our Goddard Space Flight Center worked to build this smart-car-sized instrument to exacting requirements so that scientists can measure minute changes in our planet’s ice.

Sea ice is seen in front of Apusiaajik Glacier in Greenland. Credit: NASA/JPL-Caltech/Jim Round

Two Types of Ice

Not all ice is the same. Land ice, like the ice sheets in Greenland and Antarctica, or glaciers dotting the Himalayas, builds up as snow falls over centuries and forms compacted layers. When it melts, it can flow into the ocean and raise sea level. Sea ice, on the other hand, forms when ocean water freezes. It can last for years, or a single winter. When sea ice disappears, there is no effect on sea level (think of a melting ice cube in your drink), but it can change climate and weather patterns far beyond the poles.

3-Dimensional Earth

ICESat-2 will measure elevation to see how much glaciers, sea ice and ice sheets are rising or falling. Our fleet of satellites collect detailed images of our planet that show changes to features like ice sheets and forests, and with ICESat-2’s data, scientists can add the third dimension – height – to those portraits of Earth.

Four Seasons, Four Measurements

ICESat-2’s orbit will make 1,387 unique ground tracks around Earth in 91 days – and then start the same ground pattern again at the beginning. This allows the satellite to measure the same ground tracks four times a year and scientists to see how glaciers and other frozen features change with the seasons – including over winter.

532 Nanometer Wavelength

The ATLAS instrument will measure ice with a laser that shines at 532 nanometers – a bright green on the visible spectrum. When these laser photons return to the satellite, they pass through a series of filters that block any light that’s not exactly at this wavelength. This helps the instrument from being swamped with all the other shades of sunlight naturally reflected from Earth.

Six Laser Beams

While the first ICESat satellite (2003-2009) measured ice with a single laser beam, ICESat-2 splits its laser light into six beams – the better to cover more ground (or ice). The arrangement of the beams into three pairs will also allow scientists to assess the slope of the surface they’re measuring.

Seven Kilometers Per Second

ICESat-2 will zoom above the planet at 7 km per second (4.3 miles per second), completing an orbit around Earth in 90 minutes. The orbits have been set to converge at the 88-degree latitude lines around the poles, to focus the data coverage in the region where scientists expect to see the most change.

800-Picosecond Precision

All of those height measurements come from timing the individual laser photons on their 600-mile roundtrip between the satellite and Earth’s surface – a journey that is timed to within 800 picoseconds. That’s a precision of nearly a billionth of a second. Our engineers had to custom build a stopwatch-like device, because no existing timers fit the strict requirements.

Nine Years of Operation IceBridge

As ICESat-2 measures the poles, it adds to our record of ice heights that started with the first ICESat and continued with Operation IceBridge, an airborne mission that has been flying over the Arctic and Antarctic for nine years. The campaign, which bridges the gap between the two satellite missions, has flown since 2009, taking height measurements and documenting the changing ice.

10,000 Pulses a Second

ICESat-2’s laser will fire 10,000 times in one second. The original ICESat fired 40 times a second. More pulses mean more height data. If ICESat-2 flew over a football field, it would take 130 measurements between end zones; its predecessor, on the other hand, would have taken one measurement in each end zone.

And One Bonus Number: 300 Trillion

Each laser pulse ICESat-2 fires contains about 300 trillion photons! Again, the laser instrument is so precise that it can time how long it takes individual photons to return to the satellite to within one billionth of a second. 

Learn more about ICESat-2: https://www.nasa.gov/icesat-2

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Our sun is dynamic and ever-changing. On Friday, July 14, a solar flare and a coronal mass ejection erupted from the same, large active region. The coils arcing over this active region are particles spiraling along magnetic field lines.

Solar flares are explosions on the sun that send energy, light and high-speed particles into space. Such flares are often associated with solar magnetic storms known as coronal mass ejections. While these are the most common solar events, the sun can also emit streams of very fast protons – known as solar energetic particle (SEP) events – and disturbances in the solar wind known as corotating interaction regions (CIRs).

Learn more HERE.

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When you're finally up out of the air, high enough to see the Earth, what is it like to see our home planet from above for the first time?

Celebrate Earth Day with NASA

"We came all this way to explore the Moon, and the most important thing is that we discovered the Earth." - Apollo 8 astronaut Bill Anders

On Dec. 24, 1968, Anders snapped this iconic photo of "Earthrise" during the historic Apollo 8 mission. As he and fellow astronauts Frank Borman and Jim Lovell became the first humans to orbit the Moon, they witnessed Earth rising over the Moon's horizon. The image helped spark the first #EarthDay on April 22, 1970.

Anders sat down with Dr. Kate Calvin, our chief scientist and senior climate advisor, to chat about the photo, and NASA’s role in studying our home.

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20 Years of the Solar and Heliospheric Observatory

The Solar and Heliospheric Observatory, SOHO for short, has captured the imagination of scientists and the public alike for two decades now. We teamed up with the European Space Agency (ESA) on SOHO, which observes the sun from space. It was launched 20 years ago this week, on Dec. 2, 1995, with the mission to study the internal structure of our neighborhood star, its atmosphere and the origin of the solar wind. SOHO sends spectacular data daily, and has led scientists to a wealth of understanding.

Here are the top 5 things you need to know about SOHO, the sun and other solar observation missions:

1. SOHO Set Out for Space with an Ambitious Mission

SOHO was designed to answer three fundamental scientific questions about the sun: What are the structure and dynamics of the solar interior? Why does the solar corona exist and how is it heated to such an extremely high temperature? Where is the solar wind produced and how is it accelerated? Clues about the solar interior come from studying seismic waves that appear as ripples on the sun's surface, a technique called helioseismology.

2. SOHO Enjoys a Great View

SOHO commands an uninterrupted view of the sun, while always staying within easy communication range of controllers at home. The space-based observatory moves around the sun in step with the Earth, by slowly orbiting around a unique point in space called the First Lagrangian Point (L1). There, the combined gravity of the Earth and sun keep SOHO in a position that's always between the sun and the Earth. The L1 point is about 1 million miles (about 1.5 million kilometers) away from Earth (about four times the distance to the Moon).

3. Bonus Discoveries: Lots of Comets

Besides watching the sun, SOHO has become the most prolific discoverer of comets in astronomical history. In September 2015, SOHO found its 3000th comet. Sometimes the spacecraft's instruments capture comets plunging to their death as they collide with the sun.

4. Extra Innings

SOHO was meant to operate until 1998, but it was so successful that ESA and NASA decided to prolong its life several times and endorsed several mission extensions. Because of this, the mission has been able to observe an entire 11-year solar cycle and much of the next.

5. Keep Your Eye (Safely) on the Sun

You can see what SOHO sees, almost in real time. The latest images from the spacecraft, updated several times daily, are available online. Take a look HERE. 

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New Sun Science Stamps from the U.S. Postal Service

To start off the summer, the U.S. Postal Service issued a set of stamps showcasing views of the Sun from our Solar Dynamics Observatory!

Since its launch in 2010, the Solar Dynamics Observatory (or SDO) has kept up a near-constant watch on the Sun from its vantage point in orbit around Earth. SDO watches the Sun in more than 10 different types of light, including some that are absorbed by Earth’s atmosphere so can only be seen from space. These different types of light allow scientists to study different parts of the Sun – from its surface to its atmosphere – and better understand the solar activity that can affect our technology on Earth and in space.

The new set of stamps features 10 images from SDO. Most of these images are in extreme ultraviolet light, which is invisible to human eyes.

Let’s explore the science behind some of the stamps!

Coronal hole (May 2016)

The dark area capping the northern polar region of the Sun is a coronal hole, a magnetically open area on the Sun from which high-speed solar wind escapes into space. Such high-speed solar wind streams can spark magnificent auroral displays on Earth when they collide with our planet’s magnetic field.

Solar flare (August 2011)

The bright flash on the Sun’s upper right is a powerful solar flare. Solar flares are bursts of light and energy that can disturb the part of Earth’s atmosphere where GPS and radio signals travel.

Active Sun (October 2014)

This view highlights the many active regions dotting the Sun’s surface. Active regions are areas of intense and complex magnetic fields on the Sun – linked to sunspots – that are prone to erupting with solar flares or explosions of material called coronal mass ejections.

Plasma blast (August 2012)

These images show a burst of material from the Sun, called a coronal mass ejection. These eruptions of magnetized solar material can create space weather effects on Earth when they collide with our planet’s magnetosphere, or magnetic environment – including aurora, satellite disruptions, and, when extreme, even power outages.

Coronal loops (July 2012)

These images show evolving coronal loops across the limb and disk of the Sun. Just days after these images were taken, the Sun unleashed a powerful solar flare.

Coronal loops are often found over sunspots and active regions, which are areas of intense and complex magnetic fields on the Sun.

Sunspots (October 2014)

This view in visible light – the type of light we can see – shows a cluster of sunspots near the center of the Sun. Sunspots appear dark because they are relatively cool compared to surrounding material, a consequence of the way their extremely dense magnetic field prevents heated material from rising to the solar surface.

For more Sun science, follow NASA Sun on Twitter, on Facebook, or on the web.

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Questions coming up from….

@teamadamsperret: Congrats on your PhD!! When people ask what you do, what's your reply?

@Anonymous: How does it feel, working in NASA?

@moonlighy: How did you find your love for this job?

@redbullanddepression: what the prettiest star in the sky in your opinion? also, you are a great role model as a queer woman who is attending university next year to major in aerospace engineering!!!

We’re With You When You Fly

Did you know that "We’re With You When You Fly”? Thanks to our advancements in aeronautics, today’s aviation industry is better equipped than ever to safely and efficiently transport millions of passengers and billions of dollars worth of freight to their destinations. In fact, every U.S. Aircraft flying today and every U.S. air traffic control tower uses NASA-developed technology in some way. Here are some of our objectives in aeronautics:

Making Flight Greener

From reducing fuel emissions to making more efficient flight routes, we’re working to make flight greener. We are dedicated to improving the design of airplanes so they are more Earth friendly by using less fuel, generating less pollution and reducing noise levels far below where they are today.

Getting you safely home faster

We work with the Federal Aviation Administration to provide air traffic controllers with new tools for safely managing the expected growth in air traffic across the nation. For example, testing continues on a tool that controllers and pilots can use to find a more efficient way around bad weather, saving thousands of pounds of fuel and an average of 27 minutes flying time per tested flight. These and other NASA-developed tools help get you home faster and support a safe, efficient airspace.

Seeing Aviation’s Future

Here at NASA, we’re committed to transforming aviation through cutting edge research and development. From potential airplanes that could be the first to fly on Mars, to testing a concept of a battery-powered plane, we’re always thinking of what the future of aviation will look like.

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Before my question I would like to congratulate you on your career at Nasa, it must be amazing to work there even if you didn’t achieve your dream of being an astronaut, you can still lead missions from the ground. (Sorry if my punctuation is a bit off) as for my question, what has it been like to work at nasa all of these years and get to help with so many missions? Do you ever get nervous for the people who’s lives are in your hands? Signed ~ Phillip