What’s better than taking a picture of a cloud to figure out its size and shape? Taking a bunch of pictures all around it. That way you get a three-dimensional view without having to worry about missing something. The HARP CubeSat is going to do just that: make observations of cloud droplets and tiny airborne particles like soot and dust with a modified camera lens from multiple angles. This will give us a full rendering of what’s going on inside the clouds, specifically, how those airborne particles act as “seeds” for water vapor to condense on and form cloud droplets. Since so many of those particles are in the air as a result of man-made pollution, we want to understand how they may be affecting clouds, weather and climate.
Anyone who’s worn a black shirt on a summer day knows how much sunlight and heat it absorbs. The RAVAN 3-unit CubeSat, however, carries “blacker than black” technology – carbon nanotubes set up like a bundle of drinking straws that suck up nearly all the sunlight and energy that reach them to the point that your black shirt seems merely dark grey in comparison. Flying in low Earth orbit, RAVAN’s super sensitive instrument will detect tiny changes in the amount of sunlight and energy passing into and out of the top of the atmosphere. The amount of energy passing through the top of the atmosphere is where the net accounting of Earth’s energy budget happens – one of the major measurements we need in order to understand the effects of greenhouse gases on global warming and climate change.
That long skinny piece coming out of the bottom right side under the solar panel? That’s a measuring tape. It’s doubling as a communications antenna on the MiRaTA CubeSat that will be a mini-weather station in space. This 3-unit, shoe box-sized satellite is testing out new, miniaturized technology to measure temperature, water vapor, and cloud ice in the atmosphere. They’ll be tracking major storms, including hurricanes, as well as everyday weather. If this test flight is successful, the new, smaller technology will likely be incorporated into major – large – weather satellite missions in the future that are part of our national infrastructure.
The aptly named IceCube will measure – you guessed it – ice in our atmosphere. Unlike the droplets that make up rain, ice is one of the harder things to measure from space. IceCube is a 3-unit CubeSat about the size of a loaf of bread outfitted with a new high-frequency microwave radiometer, an instrument that measures naturally occurring radiation emitted by stuff in the atmosphere – cloud droplets, rain, and the ice particles at the tops of clouds. This will be the first space test of the new microwave radiometer that has to balance its tiny size and low power with being sensitive enough to detect cloud ice.
What do GPS signals do when they’re not talking to your phone? A lot of them are just bouncing harmlessly off the planet’s surface – a fact that the CYGNSS mission is taking advantage of to measure wind speed over the ocean. Eight identical small satellites, each about the size of a microwave oven, flying in formation carry custom modified GPS receivers pointed at the oceans. When the water is smooth – not windy – the GPS signals reflect back uniformly, like the moon on a pond reflected as if in a mirror. When the water is choppy – windy – the signals reflect back in in the same direction but distorted, like the moon reflection on a choppy pond being distorted by ripples. Flying eight satellites in formation means the CYGNSS mission can measure wind speed across more of the ocean at once, which will help with understanding tropical storms and hurricanes.
An important way to improve forecasts of hurricane and tropical cyclone intensity is to see what’s going on inside and around them while they’re happening. That’s the goal of the TROPICS mission, 12 CubeSats that will fly in formation to track the temperature and humidity of storm environments. The TROPICS CubeSats will get very frequent measurements, similar to X-rays, that cut through the overall cloud-cover so we can see the storm’s underlying structure. The storm structures known as the eyewall – tall clouds, wind and rain around the eye – and rainbands – the rainy parts of the spiral arms – give us clues about whether a storm is primed to intensify into a category 4 or 5 storm, something everyone in their path needs to know.
Learn more the world of small satellites at: https://www.nasa.gov/mission_pages/smallsats
Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com
Science is a shared endeavor. We learn more when we work together. Today, July 18, we’re using three different space telescopes to observe the same star/planet system!
As our Transiting Exoplanet Survey Satellite (TESS) enters its third year of observations, it's taking a new look at a familiar system this month. And today it won't be alone. Astronomers are looking at AU Microscopii, a young fiery nearby star – about 22 million years old – with the TESS, NICER and Swift observatories.
TESS will be looking for more transits – the passage of a planet across a star – of a recently-discovered exoplanet lurking in the dust of AU Microscopii (called AU Mic for short). Astronomers think there may be other worlds in this active system, as well!
Our Neutron star Interior Composition Explorer (NICER) telescope on the International Space Station will also focus on AU Mic today. While NICER is designed to study neutron stars, the collapsed remains of massive stars that exploded as supernovae, it can study other X-ray sources, too. Scientists hope to observe stellar flares by looking at the star with its high-precision X-ray instrument.
Scientists aren't sure where the X-rays are coming from on AU Mic — it could be from a stellar corona or magnetic hot spots. If it's from hot spots, NICER might not see the planet transit, unless it happens to pass over one of those spots, then it could see a big dip!
A different team of astronomers will use our Neil Gehrels Swift Observatory to peer at AU Mic in X-ray and UV to monitor for high-energy flares while TESS simultaneously observes the transiting planet in the visible spectrum. Stellar flares like those of AU Mic can bathe planets in radiation.
Studying high-energy flares from AU Mic with Swift will help us understand the flare-rate over time, which will help with models of the planet’s atmosphere and the system’s space weather. There's even a (very) small chance for Swift to see a hint of the planet's transit!
The flares that a star produces can have a direct impact on orbiting planets' atmospheres. The high-energy photons and particles associated with flares can alter the chemical makeup of a planet's atmosphere and erode it away over time.
Another time TESS teamed up with a different spacecraft, it discovered a hidden exoplanet, a planet beyond our solar system called AU Mic b, with the now-retired Spitzer Space Telescope. That notable discovery inspired our latest poster! It’s free to download in English and Spanish.
Spitzer’s infrared instrument was ideal for peering at dusty systems! Astronomers are still using data from Spitzer to make discoveries. In fact, the James Webb Space Telescope will carry on similar study and observe AU Mic after it launches next year.
Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com
This artist’s concept gives a cutaway view of the Skylab orbital workshop, which launched 50 years ago on May 14, 1973. Established in 1970, the Skylab Program's goals were to enrich our scientific knowledge of Earth, the sun, the stars, and cosmic space; to study the effects of weightlessness on living organisms; to study the effects of the processing and manufacturing of materials in the absence of gravity; and to conduct Earth-resource observations.
Three crews visited Skylab and carried out 270 scientific and technical investigations in the fields of physics, astronomy, and biological sciences. They also proved that humans could live and work in outer space for extended periods of time, laying the groundwork for the International Space Station.
Make sure to follow us on Tumblr for your regular dose of space!
A new NASA study provides space-based evidence that Earth’s tropical regions were the cause of the largest annual increases in atmospheric carbon dioxide concentration seen in at least 2,000 years.
What was the cause of this?
Scientists suspect that the 2015-2016 El Niño – one of the largest on record – was responsible. El Niño is a cyclical warming pattern of ocean circulation in the Pacific Ocean that affects weather all over the world. Before OCO-2, we didn’t have enough data to understand exactly how El Nino played a part.
Analyzing the first 28 months of data from our Orbiting Carbon Observatory (OCO-2) satellite, researchers conclude that impacts of El Niño-related heat and drought occurring in the tropical regions of South America, Africa and Indonesia were responsible for the record spike in global carbon dioxide.
These three tropical regions released 2.5 gigatons more carbon into the atmosphere than they did in 2011. This extra carbon dioxide explains the difference in atmospheric carbon dioxide growth rates between 2011 and the peak years of 2015-16.
In 2015 and 2016, OCO-2 recorded atmospheric carbon dioxide increases that were 50% larger than the average increase seen in recent years preceding these observations.
In eastern and southern tropical South America, including the Amazon rainforest, severe drought spurred by El Niño made 2015 the driest year in the past 30 years. Temperatures were also higher than normal. These drier and hotter conditions stressed vegetation and reduced photosynthesis, meaning trees and plants absorbed less carbon from the atmosphere. The effect was to increase the net amount of carbon released into the atmosphere.
In contrast, rainfall in tropical Africa was at normal levels, but ecosystems endured hotter-than-normal temperatures. Dead trees and plants decomposed more, resulting in more carbon being released into the atmosphere.
Meanwhile, tropical Asia had the second-driest year in the past 30 years. Its increased carbon release, primarily from Indonesia, was mainly due to increased peat and forest fires - also measured by satellites.
We knew El Niños were one factor in these variations, but until now we didn’t understand, at the scale of these regions, what the most important processes were. OCO-2’s geographic coverage and data density are allowing us to study each region separately.
Why does the amount of carbon dioxide in our atmosphere matter?
The concentration of carbon dioxide in Earth’s atmosphere is constantly changing. It changes from season to season as plants grow and die, with higher concentrations in the winter and lower amounts in the summer. Annually averaged atmospheric carbon dioxide concentrations have generally increased year over year since the 1800s – the start of the widespread Industrial Revolution. Before then, Earth’s atmosphere naturally contained about 595 gigatons of carbon in the form of carbon dioxide. Currently, that number is 850 gigatons.
Carbon dioxide is a greenhouse gas, which means that it can trap heat. Since greenhouse gas is the principal human-produced driver of climate change, better understanding how it moves through the Earth system at regional scales and how it changes over time are important aspects to monitor.
Get more information about these data HERE.
Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com.
We continue to make progress toward the first launch of our Space Launch System (SLS) rocket for the Artemis I mission around the Moon. Engineers at NASA’s Stennis Space Center near Bay St. Louis, Mississippi are preparing for the last two tests of the eight-part SLS core stage Green Run test series.
The test campaign is one of the final milestones before our SLS rocket launches America’s Orion spacecraft to the Moon with the Artemis program. The SLS Green Run test campaign is a series of eight different tests designed to bring the entire rocket stage to life for the first time.
As our engineers and technicians prepare for the wet dress rehearsal and the SLS Green Run hot fire, here are some numbers to keep in mind:
The SLS rocket’s core stage is the largest rocket stage we have ever produced. From top to bottom of its four RS-25 engines, the rocket stage measures 212 feet.
For each of the Green Run tests, the SLS core stage is installed in the historic B-2 Test Stand at Stennis. The test stand was updated to accommodate the SLS rocket stage and is 35 stories tall – or almost 350 feet!
All four RS-25 engines will operate simultaneously during the final Green Run Hot Fire. Fueled by the two propellant tanks, the cluster of engines will gimbal, or pivot, and fire for up to eight minutes just as if it were an actual Artemis launch to the Moon.
Our brawny SLS core stage is outfitted with three flight computers and special avionics systems that act as the “brains” of the rocket. It has 18 miles of cabling and more than 500 sensors and systems to help feed fuel and direct the four RS-25 engines.
The stage has two huge propellant tanks that collectively hold 733,000 gallons of super-cooled liquid hydrogen and liquid oxygen. The stage weighs more than 2.3 million pounds when its fully fueled.
It’ll take 114 trucks – 54 trucks carrying liquid hydrogen and 60 trucks carrying liquid oxygen – to provide fuel to the SLS core stage.
A series of barges will deliver the propellant from the trucks to the rocket stage installed in the test stand. Altogether, six propellant barges will send fuel through a special feed system and lines. The propellant initially will be used to chill the feed system and lines to the correct cryogenic temperature. The propellant then will flow from the barges to the B-2 Test Stand and on into the stage’s tanks.
All eight of the Green Run tests and check outs will produce more than 100 terabytes of collected data that engineers will use to certify the core stage design and help verify the stage is ready for launch.
For comparison, just one terabyte is the equivalent to 500 hours of movies, 200,000 five-minute songs, or 310,000 pictures!
The B-2 Test Stand has a flame deflector that will direct the fire produced from the rocket’s engines away from the stage. Nearly 33,000 tiny, handmade holes dot the flame deflector. Why? All those minuscule holes play a huge role by directing constant streams of pressurized water to cool the hot engine exhaust.
When NASA conducts the SLS Green Run Hot Fire test at Stennis, it’ll be the first time that the SLS core stage operates just as it would on the launch pad. This test is just a preview of what’s to come for Artemis I!
The Space Launch System is the only rocket that can send NASA astronauts aboard NASA’s Orion spacecraft and supplies to the Moon in a single mission. The SLS core stage is a key part of the rocket that will send the first woman and the next man to the Moon through NASA’s Artemis program.
Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com
From people and pets to pens and pencils, everything gives off energy in the form of heat. We’ve got special instruments that measure thermal wavelengths, so we can tell whether something is hot, cold or in between. Hotter things emit more thermal energy; colder ones emit less.
We have special instruments in space, zipping around Earth and measuring the hottest and coldest places on our planet.
We can also measure much subtler changes in heat – like when plants cool down as they take up water from the soil and ‘sweat’ it out into the air, in a process called evapotranspiration.
This lets us identify healthy, growing crops around the world.
The instrument that can do all this is called the Thermal Infrared Sensor 2 (TIRS-2). It just passed a series of rigorous tests at our Goddard Space Flight Center in Greenbelt, Md., proving it’s ready to survive in space.
TIRS-2 is bound for the Landsat 9 satellite, which will continue decades of work studying our planet from space.
Learn more about TIRS-2 and how we see heat from space: https://www.nasa.gov/feature/goddard/2019/new-landsat-infrared-instrument-ships-from-nasa/.
Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com.
Our Voyager 1 spacecraft officially became the first human-made object to venture into interstellar space in 2012.
Whether and when our Voyager 1 spacecraft broke through to interstellar space, the space between stars, has been a thorny issue.
In 2012, claims surfaced every few months that Voyager 1 had “left our solar system.” Why had the Voyager team held off from saying the craft reached interstellar space until 2013?
Basically, the team needed more data on plasma, which is an ionozied gas that exists throughout space. (The glob of neon in a storefront sign is an example of plasma).
Plasma is the most important marker that distinguishes whether Voyager 1 is inside the solar bubble, known as the heliosphere. The heliosphere is defined by the constant stream of plasma that flows outward from our Sun – until it meets the boundary of interstellar space, which contains plasma from other sources.
Adding to the challenge: they didn’t know how they’d be able to detect it.
No one has been to interstellar space before, so it’s like traveling with guidebooks that are incomplete.
Additionally, Voyager 1’s plasma instrument, which measures the density, temperature and speed of plasma, stopped working in 1980, right after its last planetary flyby.
When Voyager 1 detected the pressure of interstellar space on our heliosphere in 2004, the science team didn’t have the instrument that would provide the most direct measurements of plasma.
Voyager 1 Trajectory
Instead, they focused on the direction of the magnetic field as a proxy for source of the plasma. Since solar plasma carries the magnetic field lines emanating from the Sun and interstellar plasma carries interstellar magnetic field lines, the directions of the solar and interstellar magnetic fields were expected to differ.
Voyager 2 Trajectory
In May 2012, the number of galactic cosmic rays made its first significant jump, while some of the inside particles made their first significant dip. The pace of change quickened dramatically on July 28, 2012. After five days, the intensities returned to what they had been. This was the first taste test of a new region, and at the time Voyager scientists thought the spacecraft might have briefly touched the edge of interstellar space.
By Aug. 25, when, as we now know, Voyager 1 entered this new region for good, all the lower-energy particles from inside zipped away. Some inside particles dropped by more than a factor of 1,000 compared to 2004. However, subsequent analysis of the magnetic field data revealed that even though the magnetic field strength jumped by 60% at the boundary, the direction changed less than 2 degrees. This suggested that Voyager 1 had not left the solar magnetic field and had only entered a new region, still inside our solar bubble, that had been depleted of inside particles.
Then, in April 2013, scientists got another piece of the puzzle by chance. For the first eight years of exploring the heliosheath, which is the outer layer of the heliosphere, Voyager’s plasma wave instrument had heard nothing. But the plasma wave science team had observed bursts of radio waves in 1983 and 1984 and again in 1992 and 1993. They determined these bursts were produced by the interstellar plasma when a large outburst of solar material would plow into it and cause it to oscillate.
It took about 400 days for such solar outbursts to reach interstellar space, leading to an estimated distance of 117 to 177 AU (117 to 177 times the distance from the Sun to the Earth) to the heliopause.
Then on April 9, 2013, it happened: Voyager 1’s plasma wave instrument picked up local plasma oscillations. Scientists think they probably stemmed from a burst of solar activity from a year before. The oscillations increased in pitch through May 22 and indicated that Voyager was moving into an increasingly dense region of plasma.
The above soundtrack reproduces the amplitude and frequency of the plasma waves as “heard” by Voyager 1. The waves detected by the instrument antennas can be simply amplified and played through a speaker. These frequencies are within the range heard by human ears.
When they extrapolated back, they deduced that Voyager had first encountered this dense interstellar plasma in Aug. 2012, consistent with the sharp boundaries in the charged particle and magnetic field data on Aug. 25.
In the end, there was general agreement that Voyager 1 was indeed outside in interstellar space, but that location comes with some disclaimers. They determined the spacecraft is in a mixed transitional region of interstellar space. We don’t know when it will reach interstellar space free from the influence of our solar bubble.
Voyager 1, which is working with a finite power supply, has enough electrical power to keep operating the fields and particles science instruments through at least 2020, which will make 43 years of continual operation.
Voyager 1 will continue sending engineering data for a few more years after the last science instrument is turned off, but after that it will be sailing on as a silent ambassador.
In about 40,000 years, it will be closer to the star AC +79 3888 than our own Sun.
And for the rest of time, Voyager 1 will continue orbiting around the heart of the Milky Way galaxy, with our Sun but a tiny point of light among many.
Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com.
What would you take with you to the Moon? 🧳
We’re getting ready for our Green Run Hot Fire test, which will fire all four engines of the rocket that will be used for our Artemis I mission. This test will ensure the Space Launch System rocket is ready for the first and future missions beyond Earth’s orbit, putting us one step closer to landing the first woman and the next man on the Moon!
In celebration of this important milestone, we’ve been asking everyone (yeah, you there!) to dust off your suitcase, get creative, and show us what you would take if you were heading to the Moon!
Take a moment to peruse these #oddlysatisfying #NASAMoonKits submitted by people like you, and let them inspire you to lay out your own masterpiece. Post a picture of what you’d pack for the moon using the hashtag #NASAMoonKit for a chance to be shared by us!
A stunning #NASAMoonKit in blue. 💙
Looks like a little friend is hoping to catch a ride with this #NASAMoonKit. 🐶
A #NASAMoonKit fit for an explorer. 🧭
Shout out to the monochrome #NASAMoonKit enthusiasts! 🖤
This #NASAMoonKit is thoughtfully laid out by a true fan. 📚
This geologist’s #NASAMoonKit rocks. ⛏️
Beauty in simple #NASAMoonKits. ✨
This #NASAMoonKit successfully fits into our Expert Mode — a volume of 5” by 8” by 2” (12.7 cm x 20.32 cm x 5.08 cm). The Expert Mode dimensions are based on the amount of space astronauts are allowed when they travel to the International Space Station!
Nothing like a cozy #NASAMoonKit. 🧦
This #NASAMoonKit is clearly for the builder-types! 🧸
There are four social media platforms that you can use to submit your work:
Instagram: Use the Instagram app to upload your photo or video, and in the description include #NASAMoonKit
Twitter: Share your image on Twitter and include #NASAMoonKit in the tweet
Facebook: Share your image on Facebook and include #NASAMoonKit in the post
Tumblr: Share your image in Tumblr and include #NASAMoonKit in the tags
If a #NASAMoonKit post catches our eye, we may share your post on our NASA social media accounts or share it on the Green Run broadcast!
Click here for #NASAMoonKit Terms and Conditions.
Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com
Meet BurstCube! This shoebox-sized satellite is designed to study the most powerful explosions in the cosmos, called gamma-ray bursts. It detects gamma rays, the highest-energy form of light.
BurstCube may be small, but it had a huge journey to get to space.
First, BurstCube was designed and built at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. Here you can see Julie Cox, an early career engineer, working on BurstCube’s gamma-ray detecting instrument in the Small Satellite Lab at Goddard.
BurstCube is a type of spacecraft called a CubeSat. These tiny missions give early career engineers and scientists the chance to learn about mission development — as well as do cool science!
Then, after assembling the spacecraft, the BurstCube team took it on the road to conduct a bunch of tests to determine how it will operate in space. Here you can see another early career engineer, Kate Gasaway, working on BurstCube at NASA’s Wallops Flight Facility in Virginia.
She and other members of the team used a special facility there to map BurstCube’s magnetic field. This will help them know where the instrument is pointing when it’s in space.
The next stop was back at Goddard, where the team put BurstCube in a vacuum chamber. You can see engineers Franklin Robinson, Elliot Schwartz, and Colton Cohill lowering the lid here. They changed the temperature inside so it was very hot and then very cold. This mimics the conditions BurstCube will experience in space as it orbits in and out of sunlight.
Then, up on a Goddard rooftop, the team — including early career engineer Justin Clavette — tested BurstCube’s GPS. This so-called open-sky test helps ensure the team can locate the satellite once it’s in orbit.
The next big step in BurstCube’s journey was a flight to Houston! The team packed it up in a special case and took it to the airport. Of course, BurstCube got the window seat!
Once in Texas, the BurstCube team joined their partners at Nanoracks (part of Voyager Space) to get their tiny spacecraft ready for launch. They loaded the satellite into a rectangular frame called a deployer, along with another small satellite called SNoOPI (Signals of Opportunity P-band Investigation). The deployer is used to push spacecraft into orbit from the International Space Station.
From Houston, BurstCube traveled to Cape Canaveral Space Force Station in Florida, where it launched on SpaceX’s 30th commercial resupply servicing mission on March 21, 2024. BurstCube traveled to the station along with some other small satellites, science experiments, as well as a supply of fresh fruit and coffee for the astronauts.
A few days later, the mission docked at the space station, and the astronauts aboard began unloading all the supplies, including BurstCube!
And finally, on April 18, 2024, BurstCube was released into orbit. The team will spend a month getting the satellite ready to search the skies for gamma-ray bursts. Then finally, after a long journey, this tiny satellite can embark on its big mission!
BurstCube wouldn’t be the spacecraft it is today without the input of many early career engineers and scientists. Are you interested in learning more about how you can participate in a mission like this one? There are opportunities for students in middle and high school as well as college!
Keep up on BurstCube’s journey with NASA Universe on X and Facebook. And make sure to follow us on Tumblr for your regular dose of space!
Our two long-running missions, Cassini and the Hubble Space Telescope, are providing new details about “ocean worlds,” specifically the moons of Jupiter and Saturn.
The details – discussed during our April 13 science briefing – included the announcement by the Cassini mission team that a key ingredient for life has been found in the ocean on Saturn's moon Enceladus.
Meanwhile, in 2016 Hubble spotted a likely plume erupting from Jupiter’s moon Europa at the same location as one in 2014, reenforcing the notion of liquid water erupting from the moon.
These observations are laying the groundwork for our Europa Clipper mission, planned for launch in the 2020s.
Shane Kimbrough and his Russian colleagues returned home safely after spending 173 days in space during his mission to the International Space Station.
Meanwhile, astronaut Peggy Whitson assumed command of the orbital platform and she and her crew await the next occupants of the station, which is slated to launch April 20.
We’ve announced the preliminary winner of the 2017 Student Launch Initiative that took place near our Marshall Space Fight Center, The final selection will be announced in May. The students showcased advanced aerospace and engineering skills by launching their respective model rockets to an altitude of one mile, deploying an automated parachute and safely landing them for re-use.
On April 11, a ground-breaking ceremony took place at our Langley Research Center for the new Systems Measurement Laboratory. The 175,000 square-foot facility will be a world class lab for the research and development of new measurement concepts, technologies and systems that will enable the to meet its missions in space explorations, science and aeronautics.
Space fans celebrated Yuri’s Night on April 12 at the Air and Space Museum and around the world. On April 12, 1961, cosmonaut Yuri Gagrin became the first person to orbit the Earth.
On April 12, 1981, John Young and Bob Crippin launched aboard Space Shuttle Columbia on STS-1 a two-day mission, the first of the Shuttle Program’s 30-year history.
Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com
You may have seen the famous blue marble or pale blue dot images showing Earth from 18,000 and 3.7 billion miles away, respectively. But closer to home — some 300 miles above Earth's surface — you might encounter an unfamiliar sight: vibrant swaths of red and green or purple and yellow light emanating from the upper atmosphere.
This light is airglow.
Airglow is created when atoms and molecules in the upper atmosphere, excited by sunlight, emit light to shed excess energy. Or, it can happen when atoms and molecules that have been ionized by sunlight collide with and capture a free electron. In both cases, these atmospheric particles emit light in order to relax again. The process is similar to how auroras are created, but while auroras are driven by high-energy solar wind, airglow is energized by day-to-day solar radiation.
Since sunlight is constant, airglow constantly shines throughout Earth’s atmosphere, and the result is a tenuous bubble of light that closely encases our planet. Its light is too dim to see easily except in orbit or on the ground with clear, dark skies and a sensitive camera — it’s one-tenth as bright as the light given off by all the stars in the night sky.
Airglow highlights a key part of our atmosphere: the ionosphere. Stretching from roughly 50 to 400 miles above Earth’s surface, the ionosphere is an electrified layer of the upper atmosphere generated by extreme ultraviolet radiation from the Sun. It reacts to both terrestrial weather below and solar energy streaming in from above, forming a complex space weather system. Turbulence in this ever-changing sea of charged particles can manifest as disruptions that interfere with Earth-orbiting satellites or communication and navigation signals.
Understanding the ionosphere’s extreme variability is tricky because it requires untangling interactions between the different factors at play — interactions of which we don’t have a clear picture. That’s where airglow comes in. Each atmospheric gas has its own favored airglow color, hangs out at a different height and creates airglow by a different process, so we can use airglow to study different layers of the atmosphere.
Airglow carries information on the upper atmosphere’s temperature, density, and composition, but it also helps us trace how particles move through the region itself. Vast, high-altitude winds sweep through the ionosphere, pushing its contents around the globe — and airglow’s subtle dance follows their lead, highlighting global patterns.
Two NASA missions take advantage of precisely this effect to study the upper atmosphere: ICON — short for Ionospheric Connection Explorer — and GOLD — Global-scale Observations of the Limb and Disk.
ICON focuses on how charged and neutral gases in the upper atmosphere behave and interact, while GOLD observes what drives change — the Sun, Earth’s magnetic field or the lower atmosphere — in the region.
By imaging airglow, the two missions will enable scientists to tease out how space and Earth’s weather intersect, dictating the region’s complex behavior.
Keep up with the latest in NASA's airglow and upper atmosphere research on Twitter and Facebook or at nasa.gov/sunearth.
Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com.
Explore the universe and discover our home planet with the official NASA Tumblr account
1K posts