Atmosphere - Blog Posts
What Scientists Are Learning from the Eclipse
While millions of people in North America headed outside to watch the eclipse on Aug. 21, 2017, hundreds of scientists got out telescopes, set up instruments, and prepared balloon launches – all so they could study the Sun and its complicated influence on Earth.
Total solar eclipses happen about once every 18 months somewhere in the world, but the August eclipse was rare because of its long path over land. The total eclipse lasted more than 90 minutes over land, from when it first reached Oregon to when it left the U.S. in South Carolina.
This meant that scientists could collect more data from land than during most eclipses, giving us new insight into our world and the star that powers it.
A moment in the Sun’s atmosphere
During a total solar eclipse, the Sun’s outer atmosphere, the corona, is visible from Earth. It’s normally too dim to see next to the Sun’s bright face, but, during an eclipse, the Moon blocks out the Sun, revealing the corona.
Image Credit: Peter Aniol, Miloslav Druckmüller and Shadia Habbal
Though we can study parts of the corona with instruments that create artificial eclipses, some of the innermost regions of the corona are only visible during total solar eclipses. Solar scientists think this part of the corona may hold the secrets to some of our most fundamental questions about the Sun: Like how the solar wind – the constant flow of magnetized material that streams out from the Sun and fills the solar system – is accelerated, and why the corona is so much hotter than the Sun’s surface below.
Depending on where you were, someone watching the total solar eclipse on Aug. 21 might have been able to see the Moon completely obscuring the Sun for up to two minutes and 42 seconds. One scientist wanted to stretch that even further – so he used a pair of our WB-57 jets to chase the path of the Moon’s shadow, giving their telescopes an uninterrupted view of the solar corona for just over seven and half minutes.
These telescopes were originally designed to help monitor space shuttle launches, and the eclipse campaign was their first airborne astronomy project!
These scientists weren’t the only ones who had the idea to stretch out their view of the eclipse: The Citizen CATE project (short for Continental-America Telescopic Eclipse) did something similar, but with the help of hundreds of citizen scientists.
Citizen CATE included 68 identical small telescopes spread out across the path of totality, operated by citizen and student scientists. As the Moon’s shadow left one telescope, it reached the next one in the lineup, giving scientists a longer look at the way the corona changes throughout the eclipse.
After accounting for clouds, Citizen CATE telescopes were able to collect 82 minutes of images, out of the 93 total minutes that the eclipse was over the US. Their images will help scientists study the dynamics of the inner corona, including fast solar wind flows near the Sun’s north and south poles.
The magnetized solar wind can interact with Earth’s magnetic field, causing auroras, interfering with satellites, and – in extreme cases – even straining our power systems, and all these measurements will help us better understand how the Sun sends this material speeding out into space.
Exploring the Sun-Earth connection
Scientists also used the eclipse as a natural laboratory to explore the Sun’s complicated influence on Earth.
High in Earth’s upper atmosphere, above the ozone layer, the Sun’s intense radiation creates a layer of electrified particles called the ionosphere. This region of the atmosphere reacts to changes from both Earth below and space above. Such changes in the lower atmosphere or space weather can manifest as disruptions in the ionosphere that can interfere with communication and navigation signals.
One group of scientists used the eclipse to test computer models of the ionosphere’s effects on these communications signals. They predicted that radio signals would travel farther during the eclipse because of a drop in the number of energized particles. Their eclipse day data – collected by scientists spread out across the US and by thousands of amateur radio operators – proved that prediction right.
In another experiment, scientists used the Eclipse Ballooning Project to investigate the eclipse’s effects lower in the atmosphere. The project incorporated weather balloon flights from a dozen locations to form a picture of how Earth’s lower atmosphere – the part we interact with and which directly affects our weather – reacted to the eclipse. They found that the planetary boundary layer, the lowest part of Earth’s atmosphere, actually moved closer to Earth during the eclipse, dropped down nearly to its nighttime altitude.
A handful of these balloons also flew cards containing harmless bacteria to explore the potential for contamination of other planets with Earth-born life. Earth’s stratosphere is similar to the surface of Mars, except in one main way: the amount of sunlight. But during the eclipse, the level of sunlight dropped to something closer to what you’d expect to see on Mars, making this the perfect testbed to explore whether Earth microbes could hitch a ride to the Red Planet and survive. Scientists are working through the data collected, hoping to build up better information to help robotic and human explorers alike avoid carrying bacterial hitchhikers to Mars.
Image: The small metal card used to transport bacteria.
Finally, our EPIC instrument aboard NOAA’s DSCOVR satellite provided awe-inspiring views of the eclipse, but it’s also helping scientists understand Earth’s energy balance. Earth’s energy system is in a constant dance to maintain a balance between incoming radiation from the Sun and outgoing radiation from Earth to space, which scientists call the Earth’s energy budget. The role of clouds, both thick and thin, is important in their effect on energy balance.
Like a giant cloud, the Moon during the total solar eclipse cast a large shadow across a swath of the United States. Scientists know the dimensions and light-blocking properties of the Moon, so they used ground- and space-based instruments to learn how this large shadow affects the amount of sunlight reaching Earth’s surface, especially around the edges of the shadow. Measurements from EPIC show a 10% drop in light reflected from Earth during the eclipse (compared to about 1% on a normal day). That number will help scientists model how clouds radiate the Sun’s energy – which drives our planet’s ocean currents, seasons, weather and climate – away from our planet.
For even more eclipse science updates, stay tuned to nasa.gov/eclipse.
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After 20 years in space, the Cassini spacecraft is running out of fuel. In 2010, Cassini began a seven-year mission extension in which the plan was to expend all of the spacecraft’s propellant exploring Saturn and its moons. This led to the Grand Finale and ends with a plunge into the planet’s atmosphere at 6:32 a.m. EDT on Friday, Sept. 15.
The spacecraft will ram through Saturn’s atmosphere at four times the speed of a re-entry vehicle entering Earth’s atmosphere, and Cassini has no heat shield. So temperatures around the spacecraft will increase by 30-to-100 times per minute, and every component of the spacecraft will disintegrate over the next couple of minutes…
Cassini’s gold-colored multi-layer insulation blankets will char and break apart, and then the spacecraft's carbon fiber epoxy structures, such as the 11-foot (3-meter) wide high-gain antenna and the 30-foot (11-meter) long magnetometer boom, will weaken and break apart. Components mounted on the outside of the central body of the spacecraft will then break apart, followed by the leading face of the spacecraft itself.
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Our pale blue dot, planet Earth, is seen in this video captured by NASA astronaut Jack Fischer from his unique vantage point on the International Space Station. From 250 miles above our home planet, this time-lapse imagery takes us over the Pacific Ocean’s moon glint and above the night lights of San Francisco, CA. The thin hue of our atmosphere is visible surrounding our planet with a majestic white layer of clouds sporadically seen underneath.
The International Space Station is currently home to 6 people who are living and working in microgravity. As it orbits our planet at 17,500 miles per hour, the crew onboard is conducting important research that benefits life here on Earth.
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Freaky fast and really awesome! NASA astronaut Jack Fischer posted this GIF to his social media Tuesday saying, “I was checking the view out the back window & decided to take a pic so you can see proof of our ludicrous speed! #SpaceIsAwesome”.
In case you didn’t know, the International Space Station travels 17,500 miles per hour as it orbits 250 miles above the Earth.
Currently, three humans are living and working there, conducting important science and research. The orbiting laboratory is home to more than 250 experiments, including some that are helping us determine the effects of microgravity on the human body. Research on the station will not only help us send humans deeper into space than ever before, including to Mars, but also benefits life here on Earth.
Follow NASA astronaut Jack Fischer on Instagram and Twitter.
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1,000 Days in Orbit: MAVEN’s Top 10 Discoveries at Mars
On June 17, our MAVEN (Mars Atmosphere and Volatile Evolution Mission) will celebrate 1,000 Earth days in orbit around the Red Planet.
Since its launch in November 2013 and its orbit insertion in September 2014, MAVEN has been exploring the upper atmosphere of Mars. MAVEN is bringing insight to how the sun stripped Mars of most of its atmosphere, turning a planet once possibly habitable to microbial life into a barren desert world.
Here’s a countdown of the top 10 discoveries from the mission so far:
10. Unprecedented Ultraviolet View of Mars
Revealing dynamic, previously invisible behavior, MAVEN was able to show the ultraviolet glow from the Martian atmosphere in unprecedented detail. Nightside images showed ultraviolet “nightglow” emission from nitric oxide. Nightglow is a common planetary phenomenon in which the sky faintly glows even in the complete absence of eternal light.
9. Key Features on the Loss of Atmosphere
Some particles from the solar wind are able to penetrate unexpectedly deep into the upper atmosphere, rather than being diverted around the planet by the Martian ionosphere. This penetration is allowed by chemical reactions in the ionosphere that turn the charged particles of the solar wind into neutral atoms that are then able to penetrate deeply.
8. Metal Ions
MAVEN made the first direct observations of a layer of metal ions in the Martian ionosphere, resulting from incoming interplanetary dust hitting the atmosphere. This layer is always present, but was enhanced dramatically by the close passage to Mars of Comet Siding Spring in October 2014.
7. Two New Types of Aurora
MAVEN has identified two new types of aurora, termed “diffuse” and “proton” aurora. Unlike how we think of most aurorae on Earth, these aurorae are unrelated to either a global or local magnetic field.
6. Cause of the Aurorae
These aurorae are caused by an influx of particles from the sun ejected by different types of solar storms. When particles from these storms hit the Martian atmosphere, they can also increase the rate of loss of gas to space, by a factor of ten or more.
5. Complex Interactions with Solar Wind
The interactions between the solar wind and the planet are unexpectedly complex. This results due to the lack of an intrinsic Martian magnetic field and the occurrence of small regions of magnetized crust that can affect the incoming solar wind on local and regional scales. The magnetosphere that results from the interactions varies on short timescales and is remarkably “lumpy” as a result.
4. Seasonal Hydrogen
After investigating the upper atmosphere of the Red Planet for a full Martian year, MAVEN determined that the escaping water does not always go gently into space. The spacecraft observed the full seasonal variation of hydrogen in the upper atmosphere, confirming that it varies by a factor of 10 throughout the year. The escape rate peaked when Mars was at its closest point to the sun and dropped off when the planet was farthest from the sun.
3. Gas Lost to Space
MAVEN has used measurements of the isotopes in the upper atmosphere (atoms of the same composition but having different mass) to determine how much gas has been lost through time. These measurements suggest that 2/3 or more of the gas has been lost to space.
2. Speed of Solar Wind Stripping Martian Atmosphere
MAVEN has measured the rate at which the sun and the solar wind are stripping gas from the top of the atmosphere to space today, along with details of the removal process. Extrapolation of the loss rates into the ancient past – when the solar ultraviolet light and the solar wind were more intense – indicates that large amounts of gas have been lost to space through time.
1. Martian Atmosphere Lost to Space
The Mars atmosphere has been stripped away by the sun and the solar wind over time, changing the climate from a warmer and wetter environment early in history to the cold, dry climate that we see today.
Maven will continue its observations and is now observing a second Martian year, looking at the ways that the seasonal cycles and the solar cycle affect the system.
For more information about MAVEN, visit: www.nasa.gov/maven
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Flying With Fuel From Plants: The Eco-friendly Way to Go
We eat them. We make medicines out of them. Now we’re learning how to use plants as airplane fuel that helps the environment.
Using biofuels to help power jet engines reduces particle emissions in their exhaust by as much as 50 to 70 percent, according to a new study that bodes well for airline economics and Earth’s atmosphere.
All of the aircraft, researchers and flight operations people who made ACCESS II happen. Credits: NASA/Tom Tschida
The findings are the result of a cooperative international research program led by NASA and involving agencies from Germany and Canada, and are detailed in a study published in the journal Nature.
The view from inside NASA's HU-25C Guardian sampling aircraft from very close behind the DC-8. Credits: NASA/SSAI Edward Winstead
Our flight tests collected information about the effects of alternative fuels on engine performance, emissions and aircraft-generated contrails – essentially, human-made clouds - at altitudes flown by commercial airliners.
The DC-8's four engines burned either JP-8 jet fuel or a 50-50 blend of JP-8 and renewable alternative fuel of hydro processed esters and fatty acids produced from camelina plant oil. Credits: NASA/SSAI Edward Winstead
Contrails are produced by hot aircraft engine exhaust mixing with the cold air that is typical at cruise altitudes several miles above Earth's surface, and are composed primarily of water in the form of ice crystals.
Matt Berry (left), a flight operations engineer at our Armstrong Flight Research Center, reviews the flight plan with Principal Investigator Bruce Anderson. Credits: NASA/Tom Tschida
Researchers are interested in contrails because they create clouds that would not normally form in the atmosphere, and are believed to influence Earth’s environment.
The alternative fuels tested reduced those emissions. That’s important because contrails have a larger impact on Earth’s atmosphere than all the aviation-related carbon dioxide emissions since the first powered flight by the Wright Brothers.
This photo, taken May 14, 2014, is from the CT-133 aircraft of research partner National Research Council of Canada. It shows the NASA HU-25C Guardian aircraft flying 250 meters behind NASA's DC-8 aircraft before it descends into the DC-8's exhaust plumes to sample ice particles and engine emissions. Credit: National Research Council of Canada
Researchers plan on continuing these studies to understand the benefits of replacing current fuels in aircraft with biofuels.
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Sounding Rocket Science in the Arctic
We sent three suborbital sounding rockets right into the auroras above Alaska on the evening of March 1 local time from the Poker Flat Research Range north of Fairbanks, Alaska.
Sounding rockets are suborbital rockets that fly up in an arc and immediately come back down, with a total flight time around 20 minutes.
Though these rockets don’t fly fast enough to get into orbit around Earth, they still give us valuable information about the sun, space, and even Earth itself. Sounding rockets’ low-cost access to space is also ideal for testing instruments for future satellite missions.
Sounding rockets fly above most of Earth’s atmosphere, allowing them to see certain types of light – like extreme ultraviolet and X-rays – that don’t make it all the way to the ground because they are absorbed by the atmosphere. These kinds of light give us a unique view of the sun and processes in space.
The sun seen in extreme ultraviolet light by the Solar Dynamics Observatory satellite.
Of these three rockets, two were part of the Neutral Jets in Auroral Arcs mission, collecting data on winds influenced by the electric fields related to auroras. Sounding rockets are the perfect vehicle for this type of study, since they can fly directly through auroras – which exist in a region of Earth’s upper atmosphere too high for scientific balloons, but too low for satellites.
The third rocket that launched on March 1 was part of the ISINGLASS mission (short for Ionospheric Structuring: In Situ and Ground-based Low Altitude Studies). ISINGLASS included two rockets designed to launch into two different types of auroras in order to collect detailed data on their structure, with the hope of better understanding the processes that create auroras. The initial ISINGLASS rocket launched a few weeks earlier, on Feb. 22, also from the Poker Flat Research Range in Alaska.
Auroras are caused when charged particles trapped in Earth’s vast magnetic field are sent raining down into the atmosphere, usually triggered by events on the sun that propagate out into space.
Team members at the range had to wait until conditions were just right until they could launch – including winds, weather, and science conditions. Since these rockets were studying aurora, that means they had to wait until the sky was lit up with the Northern Lights.
Regions near the North and South Pole are best for studying the aurora, because the shape of Earth’s magnetic field naturally funnels aurora-causing particles near the poles.
But launching sensitive instruments near the Arctic Circle in the winter has its own unique challenges. For example, rockets have to be insulated with foam or blankets every time they’re taken outside – including while on the launch pad – because of the extremely low temperatures.
For more information on sounding rockets, visit www.nasa.gov/soundingrockets.
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What Happened to Mars?
Billions of years ago, Mars was a very different world. Liquid water flowed in long rivers that emptied into lakes and shallow seas. A thick atmosphere blanketed the planet and kept it warm.
Today, Mars is bitter cold. The Red Planet’s thin and wispy atmosphere provides scant cover for the surface below.
Our MAVEN Mission
The Mars Atmosphere and Volatile EvolutioN (MAVEN) mission is part of our Mars Scout program. This spacecraft launched in November 2013, and is exploring the Red Planet’s upper atmosphere, ionosphere and interactions with the sun and solar wind.
The purpose of the MAVEN mission is to determine the state of the upper atmosphere of Mars, the processes that control it and the overall atmospheric loss that is currently occurring. Specifically, MAVEN is exploring the processes through which the top of the Martian atmosphere can be lost to space. Scientists think that this loss could be important in explaining the changes in the climate of Mars that have occurred over the last four billion years.
New Findings
Today, Nov. 5, we will share new details of key science findings from our ongoing exploration of Mars during a news briefing at 2 p.m. EDT. This event will be broadcast live on NASA Television. Have questions? Use #askNASA during the briefing.
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