Long Dead NASA Spacecraft Wakes Up

Jan. 26, 2018:  Amateur astronomer Scott Tilley has a hobby: He hunts spy satellites. Using an S-band radio antenna in Roberts Creek, British Columbia, he regularly scans the skies for radio signals from classified objects orbiting Earth. Since he started 5 years ago, Tilley has bagged dozens of secret or unlisted satellites. “It’s a lot of fun,” he confesses.

Earlier this month, Tilley was hunting for Zuma–a secretive United States government satellite lost in a launch mishap on Jan. 8th–when a J-shaped curve appeared on his computer screen. “It was the signature of a lost satellite,” he says, “but it was not Zuma.”

In a stroke of good luck that has dizzied space scientists, Tilley found IMAGE, a NASA spacecraft that “died” more than 10 years ago.


An artist’s concept of IMAGE flying over Earth’s north pole.

Short for “Imager for Magnetopause-to-Aurora Global Exploration,” IMAGE was launched in 2000 on a flagship mission to monitor space weather. Mapping the ebb and flow of plasma around Earth, IMAGE was able to watch our planet’s magnetosphere respond almost like a living organism to blasts of solar activity, while its ultraviolet cameras took gorgeous pictures of Earth’s global auroras.

“It had capabilities that no other spacecraft could match–before or since,” says. Patricia Reiff, a member of the original IMAGE science team at Rice University.

IMAGE was in the 5th year of its extended mission on Dec. 18, 2005, when the spacecraft suddenly went silent. No one knows why, although suspicions have focused on a power controller for the spacecraft’s transponder, which might have temporarily failed.

The one hope was a reboot: When IMAGE’s solar-powered batteries drained to zero during a eclipse by the Earth, onboard systems could restart and begin transmitting again. “If revival occurs, the mission should be able to continue as before with no limitations,” noted NASA’s IMAGE Failure Review Board in their 2006 report.

A deep eclipse in 2007, however, failed to produce the desired result. “After that, we stopped listening,” says Reiff.


Radio signals from IMAGE, detected by Scott Tilley on Jan. 20, 2018. [more]

That is, until Scott Tilley started looking for Zuma. “When I saw the radio signature, I ran a program called STRF to identify it,” he says. Developed by Cees Bassa, a professional astronomer at the Netherlands Institute for Radio Astronomy, STRF treats Earth-orbiting satellites much like binary pulsars–deducing their orbital elements from the Doppler shifts of their radio signals. “The program immediately matched the orbit of the satellite I saw to IMAGE. It was that easy,” says Tilley.

Sometime between 2007 and 2018–no one knows when–IMAGE woke up and started talking. Now, NASA has to find a way to answer.

“The good news is, NASA is working on a recovery plan,” says Reiff. “UC Berkeley still has a ground station that was used for realtime tracking and control. They are scrambling to find the old software and see it they can get the bird to respond. Apparently there are data side lobes on the transmission, so that is a good sign.”

Researchers would love to have IMAGE back. The spacecraft has a unique Big Picture view of Earth’s magnetosphere and “its global-scale auroral imager would be fantastic for nowcasting space weather,” says Reiff. “Fingers crossed!!”

Blue Moon Lunar Eclipse

Jan. 25, 2018: On Wednesday, Jan. 31st, there’s going to be a “Blue Moon”–the second full Moon in a calendar month. People who go outside to look may see a different hue: bright orange. This Blue Moon is going to be eclipsed, swallowed by copper-colored shadow of Earth for more than an hour. The eclipse will be visible from Asia, Australia, and most of North America: visibility map.

EclipsetimesPST
Other time zones: UT, EST, CST, MST, PST, HST. Credit: Larry Koehn.

The bright orange color of the eclipse may be chalked up to volcanic activity–or rather, lack thereof. Atmospheric scientist Richard Keen from the University of Colorado explains:

“During a lunar eclipse, most of the light illuminating the Moon passes through Earth’s stratosphere where it is reddened by scattering,” he says. “If the stratosphere is loaded with dust from volcanic eruptions, the eclipse will be dark. The cataclysmic explosion of Tambora in 1815, for instance, turned the Moon into a dark, starless hole in sky during two subsequent eclipses.”

But Earth is experiencing a bit of a volcanic lull. We haven’t had a major volcanic blast since 1991 when Mt Pinatubo awoke from a 500 year slumber and sprayed ten billion cubic meters of ash, rock and debris into Earth’s atmosphere. Recent eruptions have been puny by comparison and have failed to make a dent on the stratosphere. To Keen, the interregnum means one thing: “This eclipse is going to be bright and beautiful.”

opticaldepth
From “Two Centuries of Volcanic Aerosols Derived from Lunar Eclipse Records” by R.  Keen

Keen studies lunar eclipses because of what they can tell us about Earth’s energy balance. A transparent stratosphere “lets the sunshine in” and actually helps warm the Earth below. “The lunar eclipse record indicates a clear stratosphere has contributed about 0.2 degrees to warming since the 1980s.”

“Mt. Pinatubo finished a 110-year episode of frequent major eruptions that began with Krakatau in 1883,” he says. “Since then, lunar eclipses have been relatively bright, and the Jan. 31st eclipse should be no exception.”

In the USA, the best time to look is during the hours before sunrise. Western states are favored: The Moon makes first contact with the core of Earth’s shadow at 3:48 am Pacific Time, kicking off the partial eclipse. Totality begins at 4:52 am PST as Earth’s shadow engulfs the lunar disk for more than an hour. “Maximum orange” is expected around 5:30 am PST. Easternmost parts of the USA will miss totality altogether.

“I welcome any and all reports on the brightness of this eclipse for use in my volcano-climate studies,” says Keen.  While actual brightness measurements (in magnitudes) made near mid-totality are most useful, I can also make use of Danjon-scale ratings. Please be sure to note the time, method, and instruments used in your reports.” Observations may be submitted here.

visibilitymap

The Pacific Radiation Bowl

Jan. 22, 2018: For years, Spaceweather.com and the students of Earth to Sky Calculus have been flying balloons to the stratosphere to monitor cosmic rays penetrating Earth’s atmosphere. Lately, we’ve been flying the same payloads onboard airplanes. We want to map Earth’s radiation environment at aviation altitudes where millions of people are routinely exposed to elevated levels of cosmic rays.

Recently we encountered an interesting feature in data taken over the Pacific Ocean: a “radiation bowl.” On Nov. 30th, 2017, Hervey Allen, a computer scientist at the University of Oregon, carried our radiation sensors onboard a commercial flight from San Francisco, California, to Auckland, New Zealand: map. As his plane cruised at a nearly constant altitude (35,000 ft) across the equator, radiation levels gracefully dipped, then recovered, in a bowl-shaped pattern:

equatorcrossing

map2

In one way, this beautiful curve is no surprise. We expect dose rates to reach a low point near the equator, because that is where Earth’s magnetic field provides the greatest shielding against cosmic rays. Interestingly, however, the low point is not directly above the equator. A parabolic curve fit to the data shows that the actual minimum occurred at 5.5 degrees N latitude.

Is Earth’s “radiation equator” offset from the geographic equator? Very likely it is. Earth’s magnetic field is tilted with respect to Earth’s spin axis and, moreover, there are many inhomogeneities in our planetary magnetic field that may create radiation zones of interest in unexpected places.

We are now planning additional trips across the equator to map the band of least radiation girdling our planet. In fact, we are working on a dataset now that includes an equator-crossing between the USA and Chile. Stay tuned for updates.

The Sun is Dimming

Dec. 15, 2017: On Friday, Dec. 15th, at the Cape Canaveral Air Force Station in Florida, SpaceX launched a new sensor to the International Space Station named TSIS-1. Its mission: to measure the dimming of the sun. As the sunspot cycle plunges toward its 11-year minimum, NASA satellites are tracking a decline in total solar irradiance (TSI). Across the entire electromagnetic spectrum, the sun’s output has dropped nearly 0.1% compared to the Solar Maximum of 2012-2014. This plot shows the TSI since 1978 as observed from nine previous satellites:


Click here for a complete explanation of this plot.

The rise and fall of the sun’s luminosity is a natural part of the solar cycle. A change of 0.1% may not sound like much, but the sun deposits a lot of energy on the Earth, approximately 1,361 watts per square meter. Summed over the globe, a 0.1% variation in this quantity exceeds all of our planet’s other energy sources (such as natural radioactivity in Earth’s core) combined. A 2013 report issued by the National Research Council (NRC), “The Effects of Solar Variability on Earth’s Climate,” spells out some of the ways the cyclic change in TSI can affect the chemistry of Earth’s upper atmosphere and possibly alter regional weather patterns, especially in the Pacific.

NASA’s current flagship satellite for measuring TSI, the Solar Radiation and Climate Experiment (SORCE), is now more than six years beyond its prime-mission lifetime. TSIS-1 will take over for SORCE, extending the record of TSI measurements with unprecedented precision. It’s five-year mission will overlap a deep Solar Minimum expected in 2019-2020. TSIS-1 will therefore be able to observe the continued decline in the sun’s luminosity followed by a rebound as the next solar cycle picks up steam. Installing and checking out TSIS-1 will take some time; the first science data are expected in Feb. 2018. Stay tuned.

Rock Comet Approaches Earth

Dec. 11, 2017: You’ve heard of comets. But have you ever heard of a rock comet? They exist, and a big one is approaching Earth this week. 3200 Phaethon will fly past our planet on Dec. 16th only 10 million km away. Measuring 5 km in diameter, this strange object is large enough for amateur astronomers to photograph through backyard telescopes. A few nights ago, the Astronomy Club of the Sing Yin Secondary School in Hong Kong video-recorded 3200 Phaethon’s approach using a 4-inch refractor:

“We observed 3200 Phaethon from the basketball court of our school campus,” the club reports. “Our school is located close to the city center where the visual limiting magnitude is about 2 to 3. Despite the glare, we were able to record the motion of this object.” (For others who wish to do this, Bob King of Sky & Telescope has written an excellent set of observing tips.)

3200 Phaethon is the source of the annual Gemini meteor shower, which is also coming this week. Sky watchers can see dozens of Geminids per hour on Dec. 13th and 14th as gravelly bits of the rock comet disintegrate in Earth’s upper atmosphere. The best time to look is during the dark hours before sunrise when Gemini is high in the sky.

“This is 3200 Phaethon’s closest encounter with Earth until December of 2093, when it will come to within 1.8 million miles,” notes Bill Cooke of NASA’s Meteoroid Environment Office. Despite the proximity of the rock comet, he doesn’t expect to see any extra Geminids this year. “It would take at least another revolution around the sun before new material from this flyby could encounter Earth – probably longer.”

A “rock comet” is an asteroid that comes very close to the sun–so close that solar heating scorches plumes of dust right off its stony surface. 3200 Phaethon comes extremely close to the sun, only 0.14 AU away, less than half the distance of Mercury, making it so hot that lead could flow like water across its sun-blasted surface. Astronomers believe that 3200 Phaethon might occasionally grow a comet-like tail of gravelly debris–raw material for the Geminid meteor shower. Indeed, NASA STEREO-A spacecraft may have seen this happening in 2010. There is much to learn about 32900 Phaethon, which is why NASA radars will be pinging it as it passes by. Stay tuned for updates.

Atmospheric Radiation is Increasing

Dec. 9, 2017: Since the spring of 2015, Spaceweather.com and the students of Earth to Sky Calculus have been flying balloons to the stratosphere over California to measure cosmic rays. Soon after our monitoring program began, we quickly realized that radiation levels are increasing. Why? The main reason is the solar cycle. In recent years, sunspot counts have plummeted as the sun’s magnetic field weakens. This has allowed more cosmic rays from deep space to penetrate the solar system. As 2017 winds down, our latest measurements show the radiation increase continuing apace–with an interesting exception, circled in yellow:

In Sept. 2017, the quiet sun surprised space weather forecasters with a sudden outburst of explosive activity. On Sept. 3rd, a huge sunspot appeared. In the week that followed, it unleashed the strongest solar flare in more than a decade (X9-class), hurled a powerful CME toward Earth, and sparked a severe geomagnetic storm (G4-class) with Northern Lights appearing as far south as Arkansas. During the storm we quickened the pace of balloon launches and found radiation dropping to levels we hadn’t seen since 2015. The flurry of solar flares and CMEs actually pushed some cosmic rays away from Earth.

Interestingly, after the sun’s outburst, radiation levels in the stratosphere took more than 2 months to fully rebound. Now they are back on track, increasing steadily as the quiet sun resumes its progress toward Solar Minimum. The solar cycle is not expected to hit rock bottom until 2019 or 2020, so cosmic rays should continue to increase, significantly, in the months and years ahead. Stay tuned for updates as our balloons continue to fly.

Technical note: The radiation sensors onboard our helium balloons detect X-rays and gamma-rays in the energy range 10 keV to 20 MeV. These energies, which span the range of medical X-ray machines and airport security scanners, trace secondary cosmic rays, the spray of debris created when primary cosmic rays from deep space hit the top of Earth’s atmosphere.

SPOTLESS SUN SPARKS PINK AURORAS

Nov. 23, 2017: On Nov. 22nd, the face of the sun was unblemished by sunspots, and NOAA classified solar activity as “very low.”  Nevertheless, the skies above Tromsø, Norway, exploded with a remarkable outburst of pink auroras. “Suddenly, the whole valley turned white (with a hint of pink),” says Frank Meissner, who witnessed and photographed the display. “It was over after about 20 seconds.”

How bright was it? “The brightness of the auroras may be compared to the car lights in the background of my photo,” points out Meissner.

In nearby Kvaløya, aurora tour guide Marianne Bergli witnessed a surge of pink that was, if anything, even more dramatic:

“Ironically, our guests stopped taking pictures,” says Bergli. “They were awestruck and frozen to the spot by the incredible pink and green lights overhead.”

This outburst was powered by a stream of solar wind flowing from a hole in the sun’s atmosphere. Such holes are common during Solar Minimum, and they require no sunspots to form. That’s why auroras continue throughout the 11-year solar cycle.

The pink color of the outburst tells us something interesting about the solar wind on Nov. 22nd: it seems to have been unusually penetrating. Most auroras are green–a verdant glow caused by energetic particles from space hitting oxygen atoms 100 km to 300 km above Earth’s surface. Pink appears when the energetic particles descend lower than usual, striking nitrogen molecules at the 100 km level and below.

In recent winters, big displays of pink and white auroras have coincided with spotless suns often enough to make observers wonder if there is a connection.  If so, more outbursts are in the offing as the sun continues its plunge toward a deep Solar Minimum. Stay tuned for pink!

Realtime Aurora Photo Gallery

Severe Space Weather on Mars

Oct. 4, 2017: More than 150 years after it happened, scientists are still taking about the Carrington Event—a solar storm in Sept. 1859 that sparked Northern Lights as far south as Cuba and sprayed the entire surface of Earth with high energy radiation.

On our planet, such global events are rare. On Mars, they happen surprisingly often—in fact, there was one just a few weeks ago.

The storm began on Sept. 10, 2017–a day the sun was supposed to be quiet: The solar cycle is currently at low ebb, near Solar Minimum, and strong flares are rare. Nevertheless, sunspot AR2673 erupted, producing a powerful X8-class solar flare that accelerated a potent spray of charged particles into space.

In a matter of hours, a “ground level event” (GLE) was underway on Mars. GLEs occur when energetic particles normally held at bay by a planet’s atmosphere or magnetic field penetrate all the way to the ground. Mars rover Curiosity detected the radiation spike as it crawled just south of the Martian equator.

“Radiation levels suddenly doubled and they remained high for nearly two days,” says Don Hassler of the Southwest Research Institute, principal investigator for Curiosity’s Radiation Assessment Detector (RAD). “This is the largest event we have seen since Curiosity landed in 2012.”

Earth was in the line of fire, too, but our planet’s magnetic field and thick atmosphere mitigated the effect of the storm. The terrestrial GLE on Sept. 10th was restricted to polar regions and amounted to a meager 6% increase–a tiny fraction of what happened on Mars.

Mars got walloped because, simply put, it is more vulnerable to space weather. The Red Planet has no global magnetic field to protect it, and an atmosphere only 1% as thick as Earth’s. Energetic particles from the Sept. 10th explosion peppered the entire dayside surface of Mars while auroras fringed the upper atmosphere all around the globe.

NASA’s MAVEN spacecraft saw the auroras using its ultraviolet imager. “If a human had been present, with eyes sensitive to visible light, they would have probably seen Mars lit up in green light (557.7nm) much like auroras on Earth,” says Sonal Jain of the Laboratory for Atmospheric and Space Physics (LASP) at the University of Colorado.


Click to play a movie of the UV auroras on Mars

“Sonal had the excitement of being blown away when the raw data come in,” says his colleague Nick Schneider, also of LASP. “The auroras were 25 times brighter than the previous record.” Both scientists work with MAVEN data and specialize in Martian auroras.

“These global events are really interesting,” says Schneider. “On Earth It takes a truly extreme solar storm to cause global havoc thanks to the strength of our magnetic field. Mars’ lack of a global magnetic field means that planet-wide events are far more common. Indeed, since MAVEN went into Mars-orbit 3 years ago, we’ve seen a bunch of auroral displays that were probably global, even though this has been a really wimpy solar cycle.”

Hassler agrees. “Curiosity has seen 5 ground level events since 2012. They are not uncommon,” he says, “and they will probably grow stronger in the years ahead as we move through Solar Minimum and return to a more active phase of the solar cycle.”

Planners of future human missions to Mars will have to take into account the frequency of these “Martian Carrington Events,” increasingly revealed by rovers and orbiters of the Red Planet. Meanwhile, researchers are still poring over data from the latest, hoping to learn more. “Analysis of these observations, both at Mars and Earth, is just beginning,” says Hassler, “so stay tuned.”

CME Sweeps Aside Cosmic Rays

July 18,2017: On July 16th, a CME hit Earth’s magnetic field, sparking two days of geomagnetic storms and beautiful southern auroras. The solar storm cloud also swept aside some of the cosmic rays currently surrounding Earth. Spaceweather.com and the students of Earth to Sky Calculus launched a space weather balloon to the stratosphere hours after the CME arrived. We detected a 7% decrease in X-rays and gamma-rays (two tracers of secondary cosmic rays). Neutron monitors in the Arctic and Antarctic recorded similar decrements. For instance, these data from the Bartol Research Institute show a nearly 8% drop in cosmic ray neutrons reaching the South Pole:

This is called a “Forbush Decrease,” named after physicist Scott E. Forbush who first described it in the 20th century. Wherever CMEs go, cosmic rays are deflected by magnetic fields inside the solar storm clouds. As a result, when solar activity is high, cosmic radiation around Earth is relatively low–a yin-yang relationship that holds throughout all phases of the solar cycle.

Lately, cosmic rays around Earth have been intensifying as the solar cycle plunges toward minimum. The CME of July 16th reversed that trend–but only for a few days. Solar activity has returned to low levels and cosmic rays are on the rise again.

Why do we care about cosmic rays? For one thing, they penetrate commercial airlines, dosing passengers and flight crews so much that pilots are classified as occupational radiation workers. Some research shows that cosmic rays can seed clouds and trigger lightning, potentially altering weather and climate. Furthermore, there are studies ( #1, #2, #3, #4) linking cosmic rays with cardiac arrhythmias in the general population.

Giant ‘ELVE’ Appears over Europe

On April 2nd, high above a thunderstorm in the Czech republic, an enormous ring of light appeared in the night sky. Using a low-light video camera, amateur astronomer Martin Popek of Nýdek photographed the 300 km-wide donut hovering near the edge of space:

“It appeared for just a split second alongside the constellation Orion” says Popek.

This is an example of an ELVE (Emissions of Light and Very Low Frequency Perturbations due to Electromagnetic Pulse Sources). First seen by cameras on the space shuttle in 1990, ELVEs appear when a pulse of electromagnetic radiation from cloud-to-ground lightning propagates up toward space and hits the base of Earth’s ionosphere. A faint ring of deep-red light marks the broad ‘spot’ where the EMP hits.

“For this to happen, the lightning needs to be very strong–typically 150-350 kilo-Ampères,” says Oscar van der Velde, a member of the Lightning Research Group at the Universitat Politècnica de Catalunya. “For comparison, normal cloud-to-ground flashes only reach 10-30 kA.”

ELVEs often appear alongside red sprites, which are also sparked by strong lightning. Indeed, Popek’s camera caught a cluster of sprites dancing nearby.

ELVEs are elusive–and that’s an understatement. Blinking in and out of existence in only 1/1000th of a second, they are completely invisible to the human eye. For comparison, red sprites tend to last for hundredths of a second and regular lightning can scintillate for a second or more. Their brevity explains why ELVEs are a more recent discovery than other lightning-related phenomenon. Learn more about the history and physics of ELVEs here and here.

Realtime Sprite Photo Gallery