Research Highlights from NASA’s GOLD Mission

By Sarah Frazier
NASA’s Goddard Space Flight Center

A special collection of research in the Journal of Geophysical Research: Space Physics highlights the initial accomplishments of NASA’s GOLD mission. GOLD, short for Global-scale Observations of the Limb and Disk, is an ultraviolet imaging spectrograph that observes Earth from its vantage point on a commercial communications satellite in geostationary orbit.

Since beginning science operations in October 2018, GOLD has kept a constant eye on Earth’s dynamic upper atmosphere, watching changes in the Western Hemisphere, marked by changes in the temperature, composition and density of the gases in this region. 

A few highlights include:

    • Results on one source of airglow seen at night, which relies on electrons on Earth’s day side becoming ionized by sunlight, then being transported along magnetic field lines to the nightside, where they create visible airglow (Solomon, et al)
    • New evidence supporting the idea that the equatorial ionization anomaly appearing in the early morning — a prominent feature in the ionosphere with poorly-understood triggers that can disrupt radio signals — is linked to waves in the lower atmosphere (Laskar, et al)
    • New observations of planet-scale waves in the lower atmosphere that drive change in the ionosphere (Gan, et al & England, et al
    • Multi-instrument measurements of plasma bubbles — “empty” pockets in the ionosphere that can disrupt signals traveling through this region because of the sudden and unpredictable change in density — that suggest they are could be seeded by pressure waves traveling upwards from the lower atmosphere (Aa, et al)
    • Observations showing that plasma bubbles occur frequently at all of the longitudes covered by GOLD with different onset times, providing new information on the influence of the particular configuration of the geomagnetic field at these longitudes (Martinis, et al
    • Measurements of changes in the chemical composition of the thermosphere during the total solar eclipse of July 2, 2019, which give scientists an unprecedented hemisphere-wide look at how the reduction in solar radiation throughout an eclipse affects this part of the atmosphere (Aryal, et al


Read more research from the special collection on the Journal of Geophysical Research: Space Physics website, see an overview of early GOLD results from AGU’s Eos, and see more GOLD mission publications on the mission website.

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What Spring is like on Uranus and Neptune

By Miles Hatfield
NASA’s Goddard Space Flight Center

A new NASA study finds that our distant planetary neighbors, Uranus and Neptune, may have magnetic “seasons:” A time of the year when aurora glow brighter and atmospheric escape may quicken.

Study authors Dan Gershman and Gina DiBraccio, of NASA’s Goddard Space Flight Center in Greenbelt, Maryland, published the results in Geophysical Research Letters. Though these seasonal changes haven’t been directly observed, the results show that a combination of strong solar activity and Uranus’ and Neptune’s unusually tilted magnetic fields is likely to trigger them.

From Mercury to Neptune, every planet in our solar system feels the unceasing stream of the solar wind. This barrage of solar particles, traveling hundreds of miles a second, drags the Sun’s magnetic field out to space, inevitably colliding with planetary magnetic fields.

But each planet responds differently. For planets closer to the Sun, like Mercury and Earth, the solar wind can really shake things up. Strong blasts of solar wind create our northern lights – at their worst, they can even cause electrical surges that lead to blackouts. (Mercury is hit so hard that it can’t even sustain an atmosphere.)

On Jupiter and Saturn, the solar wind’s blast has little effect. This is not because they’re farther away from the Sun – the most important factor is their magnetic fields, which are optimally positioned to protect them. These planets have strong magnetic fields aligned almost perfectly vertically, like a spinning top.  As the solar wind blows past Saturn, for instance, it hits its equator, meeting its magnetic shield where it is strongest.

An animation of Saturn’s magnetosphere as measured during the Voyager 1 flyby.
Credits: NASA/Scientific Visualization Studio/Tom Bridgman

Uranus and Neptune are even farther away from that strong solar wind source, but their magnetic axes make them vulnerable. Uranus’ magnetic axis is tilted by a full 60 degrees. This means that for a portion of its 84-year-long trip around the Sun, the Sun shines almost directly into the planet’s magnetic north pole, where the planet is least protected. Neptune’s axis is similarly tilted – though only by 47 degrees.

Animated GIF showing Uranus’ magnetic field. The yellow arrow points to the Sun, the light blue arrow marks Uranus’ magnetic axis, and the dark blue arrow marks Uranus’ rotation axis.
Credits: NASA/Scientific Visualization Studio/Tom Bridgman

With that background knowledge, Gershman and DiBraccio set out to study how the solar wind would affect the ice giants. Using historical data from the Helios, Pioneer and Voyager spacecrafts, Gershman and DiBraccio measured the Sun’s magnetic field throughout the solar system.

The results showed that during intense conditions, the solar wind can be as impactful near Uranus and Neptune as it normally is near Mercury, some 1.5 billion miles closer to the Sun.

Such intense conditions aren’t even a rarity. The enhanced solar activity Gershman and DiBraccio studied occurs regularly, as part of the 11-year solar cycle. The solar cycle refers to the periodic flipping of the Sun’s magnetic field, in which activity rises and falls.  At the high point, known as solar maximum, the Sun’s magnetic field throughout space can double in strength.

If the Sun enters solar maximum when Uranus or Neptune is at the appropriate angle, the effects, Gershman and DiBraccio argue, could be extreme. These planets so far from the Sun could suddenly be driven by it. Though the seasonal effects have not yet been directly observed, the physics suggests that aurora should brighten and spread further across the planet. Globs of particles known to escape the Uranian atmosphere may do so at a quickened pace. But only a few Earth-years later, it all goes away and the planets enter a new magnetic season.

The only close-up measurements we have of the planets are from the single flyby of Voyager 2 in 1986 and 1989, respectively. But a future NASA mission to the Ice Giants may well change that, giving us the first glimpse of their other-worldly magnetic seasons.

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SDO Captures Brilliant Solar Eruption

By Karen Fox
NASA’s Goddard Space Flight Center


Credits: NASA’s Goddard Space Flight Center/SDO
Download this video

This imagery captured by NASA’s Solar Dynamics Observatory shows a solar flare and a subsequent eruption of solar material that occurred over the left limb of the Sun on November 29, 2020.  From its foot point over the limb, some of the light and energy was blocked from reaching Earth – a little like seeing light from a lightbulb with the bottom half covered up.

Also visible in the imagery is an eruption of solar material that achieved escape velocity and moved out into space as a giant cloud of gas and magnetic fields known as a coronal mass ejection, or CME. A third, but invisible, feature of such eruptive events also blew off the Sun: a swarm of fast-moving solar energetic particles. Such particles are guided by the magnetic fields streaming out from the Sun, which, due to the Sun’s constant rotation, point backwards in a big spiral much the way water comes out of a spinning sprinkler. The solar energetic particles, therefore, emerging as they did from a part of the Sun not yet completely rotated into our view, traveled along that magnetic spiral away from Earth toward the other side of the Sun.

While the solar material didn’t head toward Earth, it did pass by some spacecraft: NASA’s Parker Solar Probe, NASA’s STEREO and ESA/NASA’s Solar Orbiter. Equipped to measure magnetic fields and the particles that pass over them, we may be able to study fast-moving solar energetic particles in the observations once they are downloaded. These Sun-watching missions are all part of a larger heliophysics fleet that help us understand both what causes such eruptions on the Sun – as well as how solar activity affects interplanetary space, including near Earth, where they have the potential to affect astronauts and satellites.

To download this video and see other views of the eruption, visit NASA’s Scientific Visualization Studio page.

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Mission to study space weather moves into formulation

By Sarah Frazier
NASA’s Goddard Space Flight Center

NASA will begin formulation of a new mission to study Earth’s dynamic interface to space: the upper atmosphere. This is a region that is constantly changing, influenced by Earth’s weather percolating up from below and space weather — in the form of solar energy and space plasma — streaming in from above. This new mission will provide the first systematic study of this region in our atmospheric backyard, providing the data needed to assess, and ultimately forecast, the phenomena that course through Earth’s upper atmosphere.

The new mission, called the Geospace Dynamics Constellation, or GDC, answers a call laid out in the most recent solar and space physics decadal survey for a mission to study how Earth’s atmosphere absorbs and responds to energy inputs. GDC is a mission within NASA’s Living With a Star program, focusing on fundamental heliophysics science and applications of that science to protecting human society and technology. On Sept. 8, 2020, GDC successfully completed the Key Decision Point – A review, or KDP-A, moving the project into Phase A, when the team works on concept and technology development that will support the mission. The GDC project management has been directed to NASA’s Goddard Space Flight Center. The target Launch Readiness Date is late 2027, and GDC mission timeline will be developed during Phase A.

Data visualization showing Earth with two bands of dense plasma near the equator, complex upper atmospheric winds, and Earth's magnetic field like a belt near the middle of the planet.
This data visualization combines models of ions, upper atmospheric winds, and Earth’s magnetic field, a few of the many overlapping conditions that feed into complex processes in Earth’s upper atmosphere. The upcoming Geospace Dynamics Constellation mission will study this region of Earth’s atmosphere and provide the first systematic view of this area. Credit: NASA’s Scientific Visualization Studio

GDC will study Earth’s upper atmosphere, where our planet’s near-space environment overlaps with our atmosphere and space weather effects can manifest — ranging from the scrambling of communications and navigation signals to satellite orbit disruptions and induced currents that can trigger power outages on Earth’s surface.

Using a distributed constellation of spacecraft working together to gather comprehensive observations from multiple vantage points, GDC will explore the fundamental physics of this region of near space, investigating the complex processes that transmit energy and momentum on scales ranging from seasonal to daily to minute by minute. The level of detail and resolution provided by GDC will give us an unprecedented understanding of the space environment surrounding our home planet. Understanding these processes will provide crucial information needed to understand, and ultimately predict, the variable nature of the space environment our satellites, signals, and astronauts must travel through — and give us new insights into the forces that shape our home planet and other worlds.

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Small-Class Flare Seen on the Sun

By Mara Johnson-Groh
NASA’s Goddard Space Flight Center

Late on August 16, 2020, the Sun released a burst of light and energy known as a solar flare. This B1-class solar flare – the second smallest class of flare – peaked at 1:26p.m. EDT.

NASA’s Solar Dynamics Observatory observes the Aug. 16, 2020, B-class flare at 131, 171, and 193 angstroms. Credit: NASA/SDO

Solar flares, which are abrupt outbursts of energy and light on the solar surface, are often accompanied by CMEs. B-class flares – or “background” flares – were originally the lowest class of flare before lower level A-class flares were observed. B-class flares are relatively common; there have been at least three B-class flares in the last week.

The recent activity occurred in an otherwise quiet area of the Sun, providing an example of activity that did not originate from a sunspot – the darkened, magnetically active patches on the solar surface that often spawn flares and CMEs.

The flare was first seen by NASA’s Solar Dynamics Observatory, which has kept a constant eye on the Sun for over a decade.

 

 

Comet NEOWISE Seen in an Aurora-Filled Sky

Comet NEOWISE is visible in a sky filled with purple and green aurora
Image: Copyright Donna Lach, used with permission

Comet NEOWISE is visible in an aurora-filled sky in this photo by Aurorasaurus Ambassador Donna Lach. The photo was taken early on July 14, 2020, in western Manitoba, Canada. The purple ribbon-like structure to the left is STEVE, an aurora-related phenomenon discovered with the help of citizen scientists working with the Aurorasaurus project. The bright streak near the top of the image is a meteor.

Read more on nasa.gov.

NASA’s STEREO Sees Comet NEOWISE

By Sarah Frazier
NASA’s Goddard Space Flight Center

Comet NEOWISE appears as a streak against a starry background

This image of comet NEOWISE was captured by NASA’s Solar and Terrestrial Relations Observatory, or STEREO, on June 24, 2020, as the comet approached the Sun. The comet was visible in the field of view of STEREO’s Heliospheric Imager because of a special observing campaign: STEREO underwent a 180-degree roll on June 24 in order to observe the star Betelgeuse, whose brightness variations over the past several months have intrigued scientists. This image has been processed to increase contrast.

Credit: NASA/STEREO/William Thompson

Download additional imagery from NASA Goddard’s Scientific Visualization Studio.

A SHOT IN THE DARK: Part VII

A SHOT IN THE DARK

Chasing the aurora from the world’s northernmost rocket range

Part VII
I • II •​ ​III •​ IV •​ ​V •​ VI​ •​ VII


Rowland in his office. Credit: NASA/Miles Hatfield

Three months later, the science team convened at NASA’s Goddard Space Flight Center on the outskirts of Washington, D.C. Button-up shirts replaced down coats, their hair not ruffled from beanies and headlamps. But the mood, an eagerness to proceed, remained. Even Zaccarine — back at school and unable to make the meeting — had spent the past months helping with designs for a new instrument. It would fly on the next mission, VISIONS-3.

The next two days were filled with discussion. Each team member presented their preliminary findings, sharing open questions with the group. Each of the 11 instruments onboard captured a different part of the picture; the findings of one could often explain anomalies in the other. But telling the whole story would require many more meetings like this one.

Pfaff was the last to present, sharing the results from his electric fields experiment before departing for another meeting. The remaining members gathered around a table in Rowland’s new office, to which he had just moved after returning from Ny-Ålesund. By his estimates, Rowland would spend the next year or two here, in front of a computer screen under fluorescent lighting, analyzing data from that 15-minute rocket flight. Around him were mostly the familiar knick-knacks of his old office — books about physics, family pictures, academic regalia. Just to the right of his desk, second shelf from the bottom, was a new trinket. It was a small triangle, outlined in red, framing the silhouette of a polar bear.♦


Watch the video

A SHOT IN THE DARK: Part VI

A SHOT IN THE DARK

Chasing the aurora from the world’s northernmost rocket range

Part VI
I • II •​ ​III •​ IV •​ ​V •​ VI​ •​ VII


Doug Rowland. Credit: NASA/Joy Ng

On the snow-covered balcony, the science team huddled together in t-shirts and indoor slippers, too rushed to don their coats. Everyone was there except Rowland.

The first rocket was already in the air, but many on the team — glued to their computers until the last moments — had missed it. The flight of the second rocket would be their first chance to see the launch.

“Thirty seconds,” an unidentified voice called from inside.

The hall door opened. With only a few moments left, Rowland made his way into the huddle. The crowd lifted their phones to capture the event, but all eyes were off in the distance, staring toward the launchpad. Suddenly, all faces were illuminated. A collective sigh rose up as an intensely bright flash illuminated the terrain. Ny-Ålesund was surrounded by mountains — for the first time, they could see them.

The second VISIONS-2 rocket launches. Credit: NASA/Joy Ng

The bright orb lifted quickly into the sky, followed a few moments later by a thunderous rumble. The trail of light continued on its arc as heads craned out over the balcony. The light began to dim, then suddenly brightened again. “Second stage!” Pfaff called out, to hollers of approval. Then the rocket passed out of view.

Without a word, the entire crowd rushed for the door, running back to their computers to watch the data stream in.  As they took their places, Rowland hovered among them like a conductor surveying his orchestra.

“First images!” he called out, pointing at a screen at the first station. It was the CCD imager, nitrogen-cooled, that was now flashing images in four square boxes, arranged two-by-two on the screen. At first, they each flickered rapidly, unsynchronized. Then suddenly, a semicircle of bright light appeared in all of them. “We’ve got the limb of the Earth!” he cried — the horizon was in view. The rocket was in space, looking back down at them.

Rowland continued down the line. Next up was a particle counter, measuring the oxygen ions escaping the atmosphere as the rocket flew through them. “We got the counts?” he called. Zaccarine, still glued to her screen, raised a thumbs-up.

Rowland scanned the room. Scientists watched their data roll in, narrating each dip and turn to one another like sports announcers. Radio chatter crackled in the background. At just under four minutes into the flight, all of the instruments were on, and no problems had been reported. Rowland stood, hands on the back of an empty seat, as his eyes welled with tears. A team member reached for a handshake but Rowland went for a hug.

Moen and Pfaff, the two veterans, met him in the middle of the room for congratulations. “Everything seems to be working,” Rowland said. He smiled and looked at Pfaff. “Looks like you might make your conference after all.”

Long-exposure photo of the 39 and 40 rocket launches. Credit: NASA/Allison Stancil-Ervin

Continue to Part VII

A SHOT IN THE DARK: Part V

A SHOT IN THE DARK

Chasing the aurora from the world’s northernmost rocket range

Part V
I • II •​ ​III •​ IV •​ ​V •​ VI​ •​ VII


Rob Pfaff. Credit: NASA/Joy Ng

Pfaff paced in front of the Wall of Science, stroking his chin, weighing the signs that launchable conditions were approaching. He had spent earlier hours on the phone, rapidly rebooking flights to make his science conference on time. But that was earlier, when conditions weren’t good. Now, everyone was at full attention.

In the background, the tinny sound of voices over a video chat trickled in. Moen, the professor from Oslo, was speaking with colleagues 50 miles south in Longyearbyen. One voice belonged to Fred Sigernes, Chief of the Kjell Henriksen Observatory, who was running the all-sky imager, the instrument that detected the cusp on the Wall of Science. The other voice belonged to Kjellmar Oksavik, a professor at the University of Bergen and at UNIS in Svalbard. He was running the EISCAT radar, scanning the sky for atmospheric heating. They kept the line open as they worked, ready to discuss every bit of new data as it appeared, in real time.

One of two EISCAT radar antennas in Longyearbyen. Credit: NASA/Joy Ng

At 11 a.m. — with one hour left in the day’s launch window — the solar wind’s magnetic field started to point south.

Rowland, sensing the opportunity to launch may be drawing close, OK’d the launch team to arm the rocket. “Let’s run the clock down to three minutes,” he said. It was as close to zero as they could get. Below that, the rocket was switched to internal battery power and the engineers completed their final checks.

Fifteen minutes passed and the solar wind’s magnetic field was still pointing south, but always zig-zagging, threatening to head north at any moment. The red blob marking the cusp remained too far north above Ny-Ålesund to launch through. A call came in over a walkie-talkie, and Rowland picked it up.

“We have some concern about surface winds.” It was Range Control. “It is not really stable enough just yet, and they are quite high. If you see something you want to start the count for, we will have to assess the winds at that point to make a decision if we can go or not.”

Rowland paused, working through his options. The cusp was still too far north at the moment, but given the steady stream of southward-pointing solar wind hitting Earth, it was due to move any moment. Once it moved into the rocket’s trajectory, they needed it to heat the atmosphere before they’d be ready to launch. “We’ll let it cook for a few minutes,” Rowland responded, “and then we’ll pick up the count.”

Zaccarine stands over her computer as launch opportunity draws near. Credit: Miles Hatfield

Before Rowland finished his sentence, Pfaff was already gesturing to him. “It’s slowly moving south,” he said. They rushed out to the Wall of Science, and Pfaff pointed to the red blob marking the cusp. “This used to be up here, now it’s right on top of us.”

By 11:50 a.m., with just ten minutes left in the launch window, the atmosphere was starting to heat up. The EISCAT radar’s measurements, once cool blues and greens, were turning orange and yellow. Now, time was of the essence.

“It’s three minutes to get in the air, and another couple to get to apogee — we’re five minutes from measuring anything,” said Rowland. It wasn’t the data now, but five minutes into the future, that they depended on. Rowland turned to Moen, who spoke to his colleagues over the video chat. “Should we go?” Moen asked.

Rowland looked around to the surrounding science team. The stakes were high enough to demand a unanimous decision. If they launched toward a transient, momentary fluke of heating that disappeared before they reached it, three years of work on the mission would be wasted. But waiting too long could lead to a similar fate if they missed their only chance. “Any dissenters?” he asked.

A hushed discussion ensued over the video chat as Rowland, out of earshot, studied the Wall of Science. Pfaff leaned in to the computer to listen closely. “They’re saying go!” Pfaff yelled. Everyone turned to Rowland. That was all the resolution he needed.

Rowland notified Range Control of their decision to launch and rushed back to the Wall of Science. At the bottom left display, the clock, long frozen at three minutes, began to count down.

Continue to Part VI