Note: To celebrate the 20th anniversary of the Hubble Space Telescope, for ten days, Universe Today will feature highlights from two year slices of the life of the Hubble, focusing on its achievements as an astronomical observatory. Today’s article looks at the period April 1992 to April 1994.
“And we have liftoff, liftoff of the Space Shuttle Endeavor, on an ambitious mission to service the Hubble Space Telescope”
Without a doubt, Servicing Mission 1 in early December 1993 was the high point of the Hubble Space Telescope’s third and fourth years in space.
For starters, it successfully replaced the high speed photometer instrument with COSTAR (Corrective Optics Space Telescope Axial Replacement), which, as its name implies, corrected for the mis-figured primary mirror and so permitted the three instruments not replaced to make the high quality images intended (they were the Faint Object Camera, the Faint Object Spectrograph, and the Goddard High Resolution Spectrograph).
It also replaced the WF/PC (Wide Field Planetary Camera) with an upgraded WF/PC (called WFPC2), and made several other repairs and replacements which considerably improved the Hubble’s performance and robustness.
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John Bahcall
Well before the Hubble was launched much of its observing time was pre-allocated, especially to two Hubble Key Projects, “on the Extragalactic Distance Scale”, and the “Quasar Absorption Line” Key Project. The former is well-known (and I’ll cover it in a later Hubble 20th birthday article); the latter hardly known at all outside the astrophysics community. It was the brainchild of the remarkable John Bahcall, and much of the Hubble’s time in its first four years was devoted to it. There are 13 main papers on its results, with hundreds more based on them. In a word, this project revolutionized our understanding of the space between galaxies and galaxy clusters, all the way from just beyond the Milky Way to billions of light-years distant. The lucky 16 amateurs (Credit: NASA/STScI)
It wasn’t only professional astronomers who used the Hubble in these two years; 16 amateurs did too! Do you know what they found? If you had the chance, what would you use the Hubble to observe? Comet Shoemaker-Levy 9 (Credit: Dr H.A. Weaver, T.E. Smith; STScI/NASA)
Perhaps the most captivating images the Hubble took in these two years are the ones of Comet Shoemaker-Levy 9 on its way to a collision with Jupiter (I’ll cover the collision itself tomorrow). Do you remember, back then, that asteroid and comet threats to life on Earth just became a whole lot more believable? eta Carinae (Credit: J.Hester/Arizona State University/NASA)
3C273's jet (Credit: R.C. Thomson&C.D. Mackay, IoA, Cambridge, UK; A.E. Wright, ATNF)
Hubble sent back images of many more objects in these two years, including a much better one of eta Carinae (compare this one with the one in yesterday’s article) and the optical jet of the iconic quasar 3C273.
President Barack Obama during his speech at Kennedy Space Center on April 15, 2010. Image credit: Alan Walters (awaltersphoto.com) for Universe Today
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Speaking at Kennedy Space Center, President Barack Obama discussed his plans for NASA which includes sending astronauts to a nearby asteroid by 2025 and going to Mars by the mid-2030’s. “Let me start by being extremely clear,” Obama said. “I am 100 per cent committed to the mission of NASA and its future because broadening our capabilities in space will continue to serve us in ways we can hardly imagine.” Obama’s plan, which includes the $6 billion in additional funds for NASA over the next five years that was previously announced and using a scaled-down version of the Orion spacecraft as a rescue vehicle for the International Space Station.
Also, Obama committed funds for research now to build a heavy-lift rocket starting in 2015 — or earlier — to launch astronauts and payloads to missions beyond the Moon.
“By 2025 we expect new spacecraft designed for long journeys to allow us to begin the first ever crew missions beyond the Moon into deep space,” Obama said. “So, we’ll start by sending astronauts to an asteroid for the first time in history. By the mid-2030s, I believe we can send humans to orbit Mars and return them safely to earth, and a landing on Mars will follow.” Obama at KSC. Image credit: Alan Walters (awaltersphoto.com) for Universe Today.
Obama said his program of partnering with commercial space companies allows for more missions launched from Kennedy Space Center, an acceleration of advanced technologies that will allow for better space transportation systems and a shortening of the dependence on Russian rockets.
The president made no mention of any extension to the space shuttle program, which was one rumor that floated around before his speech.
Norm Augustine, before the president's speech. Credit: Alan Walters (awaltersphoto.com) for Universe Today
Speaking after the President, Norm Augustine – who headed the Augustine Commission review of NASA’s future, said that the new program is very close to one of the options his panel offered (option 5-B) and this path would be “worthy of a great nation, and be able to transform NASA from transportation to exploration.” Augustine also pointed out that we seem more eager to accept current Russian technology than to encourage future of our own private industry. Buzz Aldrin flew with President Obama to Kennedy Space Center in Air Force One. Image credit: Alan Walters (awaltersphoto.com) for Universe Today
The White House Chief Science Advisor John Holdren said Obama’s plan is a “faster pace to space, with more missions sooner and more affordably.” He said it’s a more visionary approach as it expands commercial capability and allows NASA to devote its resources to exploring deep space.
Obama discussed his space plan at the Operations and Checkout Building at the Kennedy Space Center, the same building used to build the Orion spacecraft. This is the first time in 12 years a sitting U.S. president has visited KSC.
The plan was originally unveiled on Feb 1, 2010, and the proposal to cancel the Constellation program and use commercial companies for trips to LEO was met with harsh criticism from members of Congress and many former astronauts, including a letter from Neil Armstrong, Gene Cernan and Jim Lovell who called the plan “devastating” the legacy of US space leadership.
Today, however, before the president’s speech, Elon Musk from SpaceX – whose Falcon 9 spacecraft will launch a test flight perhaps next month – issued a statement that lauded Obama’s plan to end Constellation.
“The President quite reasonably concluded that spending $50 billion to develop a vehicle that would cost 50% more to operate, but carry 50% less payload was perhaps not the best possible use of funds. To quote a member of the Augustine Commission, which was convened by the President to analyze Ares/Orion, ‘If Santa Claus brought us the system tomorrow, fully developed, and the budget didn’t change, our next action would have to be to cancel it,’ because we can’t afford the annual operating costs.”
“Cancellation was therefore simply a matter of time,” Musk continued, “and thankfully we have a President with the political courage to do the right thing sooner rather than later. We can ill afford the expense of an “Apollo on steroids”, as a former NASA Administrator referred to the Ares/Orion program. A lesser President might have waited until after the upcoming election cycle, not caring that billions more dollars would be wasted. It was disappointing to see how many in Congress did not possess this courage.”
By choosing KSC to make his speech Obama hoped to bring home that his program will add more 2,500 jobs compared to plan under previous administration.
“We will modernize KSC, creating jobs as we upgrade launch facilities, and bringing the potential for more jobs as companies come here to compete for launch projects. This is an area prime to lead in this competition.”
Afterwards, NASA Administrator Charlie Bolden said, “It’s special when a president talks about you but it’s even more special when he comes to visit.”
Readers, what are your thoughts on Obama’s program for NASA, and his speech?
A gallery of images from the President’s speech by Alan Walters, in attendance representing Universe Today.
Space personalities Neil deGrasse Tyson and Jim Bell at Obama's speech at KSC. Image credit: Alan Walters (awaltersphoto.com) for Universe TodayBill Nye, The Science GuyLeland Melvin was one of many astronauts in attendance at KSC. Credit: Alan Walters (awaltersphoto.com) for Universe TodaySenator Bill Nelson (D-Florida) and NASA Administrator Charlie Bolden introduced President Obama. Image Credit: Alan Walters (awaltersphoto.com) for Universe Today
NASA's Terra Satellite captured this image on April 15, 2010 of the volcano and resulting ash plume. NASA image by Jeff Schmaltz, MODIS Rapid Response Team at NASA GSFC.
A volcano under a glacier in Iceland erupted Wednesday, melting ice, shooting smoke and steam into the air and forcing hundreds of people to leave their homes. The resulting ash plume has also halted air traffic over much of Europe. Scientists said the eruption under the ice cap was 10 to 20 times more powerful than an eruption from the that happened from the Eyjafjallajokullin Volcano late last month. “This is a very much more violent eruption because it’s interacting with ice and water,” said Andy Russell, an expert in glacial flooding at the University of Newcastle in northern England, in an article on the CBC website. The dramatic footage in the video here was released today, April 15, and satellite images, below, show how far the ash plume has traveled.
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The iceland volcano sent a plume of ash and steam across the North Atlantic prompting airspace closures in the United Kingdom, Ireland, France, and Scandinavia, which then had a ripple effect, disrupting flights to and from other countries as well. Authorities could not say how long the airspace closure would last, and the ash’s spread threatened to force closures of additional airspace over the coming days.
NASA's EO-1 Satellite took this image on April 1, 2010. NASA image by Robert Simmon, using ALI data from the EO-1 team
This natural-color satellite image shows the area of the eruption on April 1, when a new vent opened up. The image was acquired by the Advanced Land Imager (ALI) aboard NASA’s Earth Observing-1 (EO-1) satellite.
The volcano, about 120 kilometres east of Reykjavik, erupted March 20 after almost 200 years of silence.
Pall Einarsson, a geophysicist at the University of Iceland, said magma was melting a hole in the thick ice covering the volcano’s crater, sending water coursing down the glacier, and causing widespread flooding.
Iceland’s main coastal ring road was closed near the volcano, and workers smashed a hole in the highway in a bid to give the rushing water a clear route to the coast and prevent a major bridge from being swept away.
Artist's impression of the Cassini spacecraft making a close pass by Saturn's inner moon Enceladus to study plumes from geysers that erupt from giant fissures in the moon's southern polar region. Copyright 2008 Karl Kofoed/NASA. Click for full size version.
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Observations from two instruments on the Cassini spacecraft shows the moon Enceladus leaves a complex pattern of ripples and bubbles in its wake as it orbit Saturn. The ringed planet’s magnetosphere is filled with electrically charged particles (plasma) originating from both the planet and its moons, and as Enceladus plows through the plasma “spiky” features form that represent bubbles of low energy particles, said Sheila Kanani who led a team of scientists from University College, London who discovered the phenomenon.
Cassini has made nine flybys of the icy, geyser-filled moon Enceladus (Saturn’s sixth-largest moon) since 2005. The closest of these have taken the spacecraft’s suite of instruments just 25 km from Enceladus’s surface, which scientists believe conceals a saline ocean. Heated vents at the south pole of the moon release a plume of material, consisting mainly of icy grains and water vapour, into space.
Measurements from the Cassini Plasma Spectrometer (CAPS) and the Magnetospheric IMaging Instrument (MIMI) show that both the moon and its plume are continuously soaking up the plasma, which rushes past at around 30 kilometers per second, leaving a cavity downstream. In addition, the most energetic particles which zoom up and down Saturn’s magnetic field lines are swept up, leaving a much larger void in the high energy plasma. Material from Enceladus, both dust and gas, is also being charged and forming new plasma.
The mysterious spiky features in the CAPS data shows a complex picture of readjustment downstream from Enceladus.
“Eventually the plasma closes the gap downstream from Enceladus but our observations show that this isn’t happening in a smooth, orderly fashion. We are seeing spiky features in the plasma that last between a few tens of seconds and a minute or two. We think that these might represent bubbles of low energy particles formed as the plasma fills the gap from different directions,” said Kanani. Since Cassini arrived at Saturn, it has been building up a picture of the vital and unexpected role that Enceladus plays in Saturn’s magnetosphere.
“Enceladus is the source of most of the plasma in Saturn’s magnetosphere, with ionised water and oxygen originating from the vents forming a big torus of plasma that surrounds Saturn. We may see these spiky features in the wake of Saturn’s other moons as they interact with the plasma but, to date, we have only studied Enceladus in sufficient detail,” said Kanani.
She presented her results at the Royal Astronomical Society’s National Astronomy Meeting in Glasgow, Scotland this week.
Lots of buzz this morning about a huge fireball seen late April 14, 2010 over at least seven midwestern US states including Wisconsin, Michigan, Iowa, Minnesota and Illinois (that’s where I am!) The video above was taken from the dashboard camera of a police vehicle in Howard County, Iowa, which is near the Minnesota border. Another video, from the University of Wisconsin-Madison caught the meteor. The flash even showed up on a National Weather Service Doppler radar image from the Quad Cities in Iowa. The image shows the fireball’s smoke trail caught at 24,000 feet (the small squiggle near Grant and Iowa counties.) Several reports (this one too!) of booms, shaking and flashes have been posted online. Did you capture any images or video? First, you might want to contact the International Meteor Organization, a nonprofit that watches over amateur meteor sightings. But we’d like to see them too! Post a link in the comments or send an email to me.
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The strength of the magnetic fields here on Earth, on the Sun, in inter-planetary space, on stars in our galaxy (the Milky Way; some of them anyway), in the interstellar medium (ISM) in our galaxy, and in the ISM of other spiral galaxies (some of them anyway) have been measured. But there have been no measurements of the strength of magnetic fields in the space between galaxies (and between clusters of galaxies; the IGM and ICM).
Up till now.
But who cares? What scientific importance does the strength of the IGM and ICM magnetic fields have?
The Large Area Telescope (LAT) on Fermi detects gamma-rays through matter (electrons) and antimatter (positrons) they produce after striking layers of tungsten. Credit: NASA/Goddard Space Flight Center Conceptual Image Lab
Estimates of these fields may provide “a clue that there was some fundamental process in the intergalactic medium that made magnetic fields,” says Ellen Zweibel, a theoretical astrophysicist at the University of Wisconsin, Madison. One “top-down” idea is that all of space was somehow left with a slight magnetic field soon after the Big Bang – around the end of inflation, Big Bang Nucleosynthesis, or decoupling of baryonic matter and radiation – and this field grew in strength as stars and galaxies amassed and amplified its intensity. Another, “bottom-up” possibility is that magnetic fields formed initially by the motion of plasma in small objects in the primordial universe, such as stars, and then propagated outward into space.
So how do you estimate the strength of a magnetic field, tens or hundreds of millions of light-years away, in regions of space a looong way from any galaxies (much less clusters of galaxies)? And how do you do this when you expect these fields to be much less than a nanoGauss (nG), perhaps as small as a femtoGauss (fG, which is a millionth of a nanoGauss)? What trick can you use??
A very neat one, one that relies on physics not directly tested in any laboratory, here on Earth, and unlikely to be so tested during the lifetime of anyone reading this today – the production of positron-electron pairs when a high energy gamma ray photon collides with an infrared or microwave one (this can’t be tested in any laboratory, today, because we can’t make gamma rays of sufficiently high energy, and even if we could, they’d collide so rarely with infrared light or microwaves we’d have to wait centuries to see such a pair produced). But blazars produce copious quantities of TeV gamma rays, and in intergalactic space microwave photons are plentiful (that’s what the cosmic microwave background – CMB – is!), and so too are far infrared ones. MAGIC telescope (Credit: Robert Wagner)
Having been produced, the positron and electron will interact with the CMB, local magnetic fields, other electrons and positrons, etc (the details are rather messy, but were basically worked out some time ago), with the net result that observations of distant, bright sources of TeV gamma rays can set lower limits on the strength of the IGM and ICM through which they travel. Severalrecentpapers report results of such observations, using the Fermi Gamma-Ray Space Telescope, and the MAGIC telescope.
So how strong are these magnetic fields? The various papers give different numbers, from greater than a few tenths of a femtoGauss to greater than a few femtoGauss.
“The fact that they’ve put a lower bound on magnetic fields far out in intergalactic space, not associated with any galaxy or clusters, suggests that there really was some process that acted on very wide scales throughout the universe,” Zweibel says. And that process would have occurred in the early universe, not long after the Big Bang. “These magnetic fields could not have formed recently and would have to have formed in the primordial universe,” says Ruth Durrer, a theoretical physicist at the University of Geneva.
So, perhaps we have yet one more window into the physics of the early universe; hooray!
Note: To celebrate the 40th anniversary of the Apollo 13 mission, for 13 days, Universe Today will feature “13 Things That Saved Apollo 13,” discussing different turning points of the mission with NASA engineer Jerry Woodfill.
While oxygen tank number two on the Apollo 13 spacecraft was an accident waiting to happen, another problem on the Saturn V rocket could have destroyed Apollo 13 before it reached Earth orbit. During the second-stage boost, the center – or inboard — engine shut down two minutes early. The shutdown wasn’t a problem, as the other four engines were able to compensate for the loss by operating for an extra four minutes. But why the engine shut down is a mystery that may have saved the mission.
“A catastrophic failure should have ensued,” said Apollo engineer Jerry Woodfill, “and would have, except for the unexplained behavior of the engine’s shutoff system. In fact, even the NASA Apollo 13 accident report fails to deal with the seriousness of the event.”
When the center engine shut down, it caused a few moments of uneasiness for Mission Control and the crew. Speaking after the flight, Commander Jim Lovell said that when NASA gave them the OK to carry on with the flight, “We all breathed a sigh of relief on the spacecraft. Hey, that was our crisis over with and we thought we’d have a smooth flight from then on.”
Woodfill said that the quick assessment in Mission Control was that a minor electrical signal failed to keep the engine operating so that it shut down prematurely. But that wasn’t the problem.
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What happened was the Saturn V rocket experienced dangerous so-called “pogo” thrust oscillations, a problem NASA knew about. While a fix had been planned for Apollo 14, time did not permit its implementation on Apollo 13’s Saturn V.
“While a clerical error caused Apollo 13’s oxygen tank to explode,” said Woodfill, “because its heater design had not been updated for 65 volt operation, and the tank was a virtual bomb (see Part 1), similarly NASA’s failure to fix a known serious booster flaw should have destroyed Apollo 13.”
The Saturn V rocket had five J-2 engines, each producing 200,000 pounds of thrust, together creating the 1 million pounds of thrust needed for a mission to the Moon.
On previous Saturn flights, these pogo oscillations had occurred during launch. The phenomenon occurred as the fuel lines and structure of the rocket resonated at a common frequency. The resonance tended to amplify in force and potential destruction with each bounce of the “pogo” mechanism. So damaging was the phenomena on the unmanned Apollo 6 mission that an entire outer panel of the Saturn 5 ejected into space. Launch of Apollo 6. Credit: NASA
“The oscillations are like a jack hammer and it was so dreadful on Apollo 6 that it tore off a panel on the booster, and threatened the mission,” said Woodfill. “Apollo 6’s orbit was supposed to be circular, but because of the pogo effect and failure of second stage engines, the orbit became an elongated orbit of about 60 by 180 miles.”
Woodfill said if Apollo 13 had ended up in that type of orbit, it would have been bad but not fatal. However, Apollo 13 was a much different situation than Apollo 6.
The Apollo 6 mission carried a mock lunar lander of more modest mass than the “full-up” lander which Apollo 13 carried to orbit. With the added mass for Apollo 13, the pogo forces were suddenly a magnitude greater in intensity. A mission report said that the engine experienced 68g vibrations at 16 hertz, flexing the thrust frame by 3 inches (76 mm).
Woodfill said that if the center engine had continued running a few more seconds, the oscillations may have destroyed the vehicle. “That engine was pounding horizontally up and down, a quarter foot, at the rate of 16 times a second,” he said. “The engine had become a two ton sledge hammer, a deadly pogo stick of destruction, putting enormous forces on the supporting structures.”
What shut the engine down?
“It is, to this day, not fully understood, but it had something to do with fooling the engine’s thrust chamber pressure sensor that pressure was too low,” said Woodfill. He has studied the mission report, but says the complete analysis of why the engine shut down isn’t included.
“Though the shutdown command came from a low thrust chamber pressure sensor assessment, actually, the engine was operating correctly,” he said. ” The sensor had nothing to do with the pogo phenomenon. For some inexplicable reason, it was like something sucked the pressure out of the chamber and a sensor turned the engine off. But no one knows exactly why.”
Woodfill said those who later examined the situation said it was altogether lucky that the sensor shut down the engine. “Something intervened, stopping the engine from pounding its way from the mount into the fragile fuel tanks. This would have destroyed the Apollo 13 launch vehicle.”
As it was, the engine shutdown likely saved the Apollo 13 mission.
Tomorrow, Part 6: Navigation
Other articles from the “13 Things That Saved Apollo 13” series:
Here’s this week’s Where In The Universe Challenge, and can you believe it — this is the 100th WITU we’ve done! Amazing! But no resting on our laurels, or yours either for that matter (thanks to you, our readers for making the WITU Challenge such as success!) But you know what to do: take a look at this image and see if you can determine where in the universe this image is from; give yourself extra points if you can name the instrument responsible for the image. We’ll provide the image today, but won’t reveal the answer until tomorrow. This gives you a chance to mull over the image and provide your answer/guess in the comment section. Please, no links or extensive explanations of what you think this is — give everyone the chance to guess.
Good Luck!
Update: The answer has now been posted below:
Answers were split down the middle, but the winners are those who said Mars. Yes, this is an image of icy layers at Mars’ north pole, taken by the HiRISE camera on the Mars Reconnaissance Orbiter. The HiRISE folks say that the Martian north polar layered deposits are an ice sheet much like the Greenland ice sheet on the Earth. Just as with the ice sheet in Greenland, this Martian ice sheet contains many layers that record variations in the Martian climate. So this is a very interesting image — and place — to study.
The date was 24 April, 1990; “Liftoff of the Space Shuttle Discovery, with the Hubble Space Telescope, our window on the universe”.
Over the next ten days I’ll be reviewing these twenty years, starting with the first two today; I hope you will enjoy the show.
Of course, the Hubble’s history goes back many years before 1990; astrophysicist Lyman Spitzer is credited with the first paper proposing a space-based optical observatory, in 1946! He spent a good half century working on the idea (Trivia fact: Spitzer really knew his plasma physics; among other things he founded the Princeton Plasma Physics Laboratory, in 1951; the PPPL is home to some exciting magnetic reconnection experiments). Not so well-known, in the US at least, is that European involvement in the Hubble – via the European Space Agency (ESA) – dates from 1975, 15 years before its launch (Trivia fact: ESA’s Space Telescope European Coordinating Facility (ST-ECF) issued its first newsletter in March 1985). HST WF/PC first light image (Credit: NASA/ESA/STScI)
For all the brilliant engineering, the best money could buy, the Hubble’s primary mirror was ground to exquisite precision and accuracy … but precisely and accurately wrong; the “presence of significant spherical aberration” was announced by NASA at the end of June, 1990. (Trivia fact: the cause of the mis-grinding was a field lens in the reflective null corrector used to test the figure of the primary mirror; it was “mis-located by about 1.3mm” Did heads roll as a result?)
However, because the primary mirror was ground so precisely and accurately, if wrongly, images sent back from the Hubble could be processed to largely remove the unintended blur, and so after a half year or so of rather intense work, the scientific show did go on. Supernova 1987A (Credit: NASA, ESA, STScI)
And what a show it was! Saturn's North Polar Hood (Credit: NASA, ESA, STScI)
Take a trip down memory lane, check out Hubble’s image of Saturn’s North Polar Hood; it’s zoomable!
But a faulty mirror and image processing are not quite the real thing; sometimes there are image processing artifacts, as this 1991 image of a nearby supernova-to-be shows: Eta Carinae (Credit: NASA, ESA)
Of course it wasn’t only pretty pictures that the Hubble returned to Earth; a great many papers based on the astronomical data from the Hubble were published in its first two years of operation, covering a wide range of topics (perhaps I’ll base a future Universe Puzzle on this, maybe ‘what was the first such paper?’). And it wasn’t only images; the Hubble carried an instrument called the Faint Object Spectrograph, which worked in a part of the electromagnetic spectrum accessible only from space, the far ultraviolet (click on this link to read about limits on He I emission, the He I Gunn-Peterson effect, and Ly-alpha absorption spectrum “at z roughly 0.5”).
What’s your favorite from the first two years? 3C 273, 2003 HST image (Credit: NASA/J.Bahcall(IAS))
Mine’s The Ultraviolet Absorption Spectrum of 3C 273; not only is about the iconic quasar 3C 273, not only is it a classic John Bahcall paper (he writes so well!), not only does it illustrate well the scientific power of spectroscopy, but shines a light on composition of the intracluster medium.
Tomorrow: 1992 and 1993, including COSTAR and the first servicing mission.
NASA’s Cassini spacecraft has captured images of lightning on Saturn, allowing the scientists to create the first movie showing lightning flashing on another planet. “Ever since the beginning of the Cassini mission, a major goal of the Imaging Team has been the detection of Saturnian lightning,” said team leader Carolyn Porco in an email. Porco said the ability to capture the lightning was a direct result of the dimming of the ringshine on the night side of the planet during last year’s Saturn equinox. “And these flashes have been shown to be coincident in time with the emission of powerful electrostatic discharges intercepted by the Cassini Radio and Plasma Wave experiment,” Porco added.
