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On June 19, 2013, the U.S. Geological Survey officially decommissioned Landsat 5 after an astonishing 29 years of operation. The satellite’s longevity was recognized by the Guinness Book of World Records, which dubbed Landsat 5 as the longest-operating Earth observation satellite.

I recently listened to Dr. Steve Covington — the flight systems manager for Landsat 5 since 2001 — recount some of the lucky circumstances and creative engineering that kept the satellite operating for nearly three decades. (The talk will be posted on the Library of Congress web site in the near future.)  Here are some of the highlights.

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Lucky circumstance 1: Landsat 5 had a twin, Landsat 4, which showed problems with its power system once it was in orbit. Those problems let engineers adjust Landsat 5 before it launched on March 1, 1984.

Lucky circumstance 2: Landsat 5 was equipped with a large auxiliary fuel tank designed to let the satellite fly down from its orbit to a lower orbit where astronauts could retrieve and repair it. The polar-orbiting space shuttle program that would enable these on-orbit repairs never got off the ground, and this left Landsat 5 with a whole lot of extra fuel. Mission operators used the fuel to extend the mission across decades.

Creative Engineering 1: In January 2005, Landsat 5′s primary solar array drive failed, and months later, in November, the backup drive failed. This key component turned the solar array to face the Sun straight on whenever the satellite was on the sunlit side of the Earth. Without the drive, the solar array was stuck in a single position, limiting the amount of energy it generated to power the instruments and spacecraft.

The failure of the drives looked to be a mission-ending event, since the Landsat 5′s batteries couldn’t be recharged sufficiently to continue science operations. But mission operation engineers came up with a novel solution: If the solar array couldn’t move, they would move the entire spacecraft. Before the satellite came across Earth’s shadow into the sunlight, they pitched the satellite to face the Sun. The satellite faced down again to acquire data, and then, approaching the shadow again, pitched out to face the Sun. This dance gave the satellite just enough extra Sun exposure to keep the batteries charged and execute its imaging duties.

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Creative Engineering 2: Landsat 5 had four pathways for sending data to the ground: two communication links with relay satellites, and two direct downlinks to ground stations. The last of these failed in 2012, preventing the satellite from sending data from its primary instrument (the Thematic Mapper) to the ground. The secondary instrument, the Multispectral Scanner (MSS) had been turned off in 1995. Mission operations engineers realized that the communication links used by MSS were still good, and the mission could continue if the MSS still worked. Seventeen years after turning the instrument off, engineers powered it back on, and amazingly, it worked. This allowed Landsat 5 to acquire one more year of data until Landsat 8 was ready to take its place in early 2013.

Do Not Adjust the Vertical…

June 12th, 2013 by Jesse Allen

One of the wonderful things about working for the Earth Observatory is that we often get first crack at examining imagery from satellites new and old. It’s been especially exciting to look at data from Landsat 8, a joint U.S. Geological Survey and NASA mission launched in February 2013.

But with new things comes new challenges. We’ve had some odd problems with the very intense memory demands of Landsat 8 imagery, for example. And when I saw the image below, I thought for sure I had stumbled on a processing error.

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This is a natural-color, pan-sharpened image of the Elbe River near Wittenberg, Germany, obtained by Landsat 8 on May 6, 2013. I had obtained this to compare to a new acquisition from June 7, 2013, which showed major flooding in the Elbe.

Oh dear. Look at that ripple pattern along the river banks. Superficially, it looks a lot like a software processing error. New code I wrote: my error, right?  In fact, at first glance, it looked a lot like Landsat data of a decade or so ago when the source files were being distributed with nearest-neighbor resampling–a technique used in remapping and resizing data which limits interactions between adjacent measures, something often useful in science measurements, but which causes jagged-looking edges.  Since this was not the first time my code had done something unexpected, it was the obvious first place to look for the cause.  The software failed me!  Again!

However, a quick glance through the data files showed that, whatever was going on, it was coming from the source data: the same rippling showed up in all the bands. Ha!  Someone else’s software had failed!

Because Landsat 8 is so new, it is easy to assume maybe I was not the only one having occasional processing problems with old software on new data. There was one more check I should have done before contacting customer service at USGS, but…

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…I didn’t think of it. If you see something odd in imagery, it is always good to check reality. In this case, a quick zoomed-in view in Google Earth (as shown here) would have informed me that the jagged edges along the banks of the river in the imagery are real jagged edges along the banks of the river.

In hindsight, there were other clues. Notice that the jagged features are present in some places and not others.  And notice that the rippled pattern along the banks bends and curves with the flow of the river. A processing artifact might only show up on very strongly contrasting features (the boundary between land and water here, for example), but would most likely be aligned consistently through the image.  It wouldn’t appear and disappear like it does here, and it would probably be more regular.  It would probably distort in the same direction every time it happened.

In the end, it turns out that all the new systems were working just fine and there really is a very oddly shaped series of features along the banks of the Elbe River near Wittenberg, presumably to stablize the banks of the river and control sediment flow.

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But there’s not much they can do in the face of severe flooding.

You’ve Come a Long Way, Landsat

June 10th, 2013 by Mike Carlowicz

Today’s guest post is from Kate Ramsayer of the NASA Earth Science News Team. Kate wrote the caption for today’s Image of the Day about El Paso and the mountains of data collected by Landsat over four decades.

When the first Landsat satellite — originally called the Earth Resources Technology Satellite (ERTS) — launched in 1972, it was no small feat to visualize the data it sent back and to conduct research with it.

“When ERTS was first launched, there was one cathode ray tube in the country that could take in the digital data and display an image,” said Jeff Masek, Landsat project scientist at NASA Goddard.

In the early years, satellite observations of the light reflected off of Earth were transmitted to receiving stations and mailed to processing centers. Computers translated the image data into photographic prints or transparencies that could be placed on light tables for interpretation. Alternatively, computers translated the numbers in each pixel into alpha-numeric symbols that were printed on large reams of paper. Analysts, often graduate students, could then color-in the symbols with crayon or magic markers. Standing on ladders over the colored-in data, they’d try to visualize the landscape represented by the maps.

“Things were pretty primitive in those days,” Masek said. “People say, ‘Why didn’t they produce a global land cover map in those first few years?’ They were lucky to be able to look at one image for a Ph.D. dissertation.”

Read more about the history of Landsat in “Landsat Looks and Sees.”

Here is the first published image from ERTS…nee, Landsat 1.

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The Tornado Chase

June 5th, 2013 by Erin Jones

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The following is a guest post from Erin Jones (pictured above), the scientific outreach lead for the Global Modeling and Assimilation Office at Goddard Space Flight Center. As a graduate student at Purdue University, she used to chase tornadoes. 

June 2, 2013, started as most Sundays do. My alarm went off; I got out of bed; I came downstairs, and I turned on my computer. I logged on to facebook. A quick look at my news feed told me that this Sunday would not be the same as most Sundays:

 Getting lots of rumors that veteran chasers were killed by the El Reno tornado. I really hope this is not real.

…  just received the news of the possible passing of Tim, Carl and Paul. We are in total shock… God rest their souls if this is true.

Hopes that messages about Tim Samaras are not true… Bad news if this is true…

I put my hand to my chest.

“No.”

The rumors were true. Tim Samaras, his son Paul, and his chase partner Carl Young were gone. They had been killed while chasing a storm on May 31 near El Reno, Oklahoma, when a large tornado hit their car and reduced it to scrap metal.

I was in shock.

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The storm that produced the El Reno tornado, as seen from the vantage point of mobile Doppler radar DOW8, near Mustang, OK. Photo courtesy of Paul Robinson.

The sad truth of the matter is that many in the community have thought for years that it was only a matter of time before a storm chaser was killed. Since the practice of storm chasing began over 50 years ago, not a single chaser had died in pursuit of a storm. Over the past several years, however, increased media coverage and TV shows like Storm Chasers have glamorized chasing and spurred the growth of an entire industry built around following storms.

The number of chasers has exploded, and it has made chasing for science more difficult and dangerous. I’ve seen it. I’ve felt what it’s like to be on a storm, just hoping that the circulation getting ready to pass over your head stays aloft because you’re stuck in chaser-induced gridlock and there’s no way you’d be able to escape if a tornado forms. I’ve known that fear. It’s like we have been on borrowed time.

As much as I dreaded the day when I would hear that a tornado had killed a storm chaser, I thought I was prepared for it. But nothing could have prepared me for what I heard on Sunday morning. Tim Samarasa pillar of the chase communitywas dead. He was a well-respected, veteran chaser. He wasn’t out for the thrill, and he wasn’t out to get the best picture or to take some extreme video. He was a serious scientist. And he was gone.

Why? How?

These questions have been at the forefront of the minds of many of my friends and colleagues over the past few days. As people begin to piece together accounts of what happened…as they process and analyze the data that were collected during the storm, a clearer picture is beginning to emerge. The tornado that hit near El Reno was more than 2.5 miles wide, making it the widest tornado ever recorded. It had a multiple vortex structure with wind speeds of up to 296 miles per hour. Toward the end of its life, it became occluded and turned northeast, deviating from its forecast path.

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Tim Samaras and Carl Young. Photo courtesy of Ryan McGinnis.

Tim Samaras and his crew had always chased safely. They knew what they were doing but it didn’t matter. Had they been caught off guard? Had they ended up stuck in traffic? Were they driving on unpaved roads that were difficult to navigate in storm conditions? Was the tornadic circulation so large that it was impossible for them to get to safety? We still don’t know.

Many of my friends were out there that day. By chance or circumstance, they all stationed themselves out of harm’s way. Three of them–Paul Robinson, Eddie Smith, and Jon Lutz–were several kilometers away from the tornado, collecting mobile Doppler radar data on the storm when it hit Tim Samaras. I asked them if they had any thoughts or stories they’d like to share about what happened.

“I’m not sure what to contribute,” Eddie said. “At the same time Paul, Jon, and I were high-fiving each other over our great positioning and the phenomenal data set we were recording, we were watching, in real-time, this thing kill our friends. How do you reconcile that?”

Jon reflected that “that thing could have killed any of us, depending on which way it turned.”

And Paul told me how he was struck by a sense of eerie irony when they ended up in Moore, Oklahoma, after fleeing the storm, where they then witnessed an EF-0 tornado disturb the same landscape that an EF-5 tornado had devastated just two weeks before.

We still don’t have a great understanding of how tornadoes form, and we still don’t know much about what the wind fields are like near the ground. Tim Samaras spent his career trying to answer these questions so that the losses due to tornadic storms might be minimized. When Tim left this world, his work was not done. It would be a disgrace to his memory if we were to stop trying to collect scientific data on severe storms and to retard the progress on tornado research that he so diligently strove for.

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During a chase on May 19, 2010, Jones’ team had to abort operations because heavy traffic made their attempts to collect data unsafe. Credit: Erin Jones.

Mammatus Clouds over Oklahoma

May 24th, 2013 by Adam Voiland

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Earth Observatory reader Warren Bonesteel sent us this shot of mammatus clouds over Duncan, Oklahoma, on May 20, 2013.  They were taken at about 7:00 p.m. CST, a few minutes after a large supercell storm passed. The same storm system spawned a violent tornado that devastated the nearby city of Moore. While most clouds form in rising air and have flat bottoms, mammatus clouds have pouch-like protrusions caused by sinking air that hang on their undersides.

Mammatus clouds can only form if the sinking air is cooler than the air around it. The sinking air must also have high water or ice content.  Though they are often associated with thunderstorms, the clouds are harmless and usually form in pockets of turbulent air after the worst of a storm has passed. They are not an indicator that a tornado is about to hit. You can learn more about mammatus clouds from  Astronomy Picture of the Day, Earth Science Picture of the Day, AccuWeather, CBC News, EarthSky, and UCAR.

Did you have other dramatic shots of this storm system that you would like to share? Please send them to adam.p.voiland@nasa.gov. I’ll add the best of what we receive to this post.

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Updates:

The photo below was taken on Sunday May 19, 2013, by Darren Purcell.  It was taken in advance of the storm that hit Norman, Oklahoma.

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GOES-13 is Down

May 23rd, 2013 by Adam Voiland

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On May 22, 2013, GOES-East, a key weather satellite that observes the eastern part of the United States stopped working normally. After initial efforts to revive the satellite failed, National Oceanic and Atmospheric Administration (NOAA) engineers have put the satellite in storage mode for troubleshooting.

Losing one of the two geostationary weather satellites that National Weather Service meteorologists rely upon could have serious consequences at any time, but that is especially true with the 2013 hurricane season just around the corner. Fortunately, NOAA had planned ahead. The agency always keeps a “spare” satellite in orbit, ready to spring into action when problems arise. On May 23, the spare satelliteGOES 14was active and had started to acquire images.

When GOES-East experienced a similar technical problem in September 2012, we published the image above showing the field of view of all three weather satellites. GOES-15, which has served as GOES-West since December 2011, is on the left and orbits at 135 degrees west longitude; GOES-14, the spare, is in the middle and resides at 105 degrees west. GOES-13, the malfunctioning satellite that has served as GOES-East since April 2010, is on the right and sits at 75 degrees west. The top row of images shows visible images acquired by the three satellites on September 15, 2012. The lower row shows the field of view of each satellite.

You can follow daily status updates on the health of GOES-13 by checking here and here. The latest GOES imagery is available here.

My 15 Favorite Commander Hadfield Photos

May 14th, 2013 by Adam Voiland

“Who’d have thought that five months away from the planet would make you feel closer to people,” mused Canadian astronaut Chris Hadfield a few days before his return trip back to Earth. Along with two crew members, the commander of International Space Station Expedition 35 landed safely in Kazakhstan on May 13, 2013, via a Russian Soyuz space capsule.

What a tour it has been. After 2,336 orbits, 62 million miles traveled, Hadfield returns as a rock star of sorts. His recording of a cover of David Bowie’s “Space Oddity” quickly went viral this week (6 million+ views and counting). But it’s not just his skill with a guitar that has attracted attention. More than anything else, it has been Hadfield’s mastery of the cameraand Twitterthat has catapulted him to fame.

Hadfield isn’t the first astronaut to tweet from space. Mike Massimino did that in 2009. But the abundance and quality of Hadfield’s tweets has set a new standard. He spent several hours per day taking photographs from the Cupola, and with the help of his son Evan (back on Earth) posted the best of them to his feed.

The photos they shared didn’t seem to be raw. One of the Hadfields must have been tweaking the brightness and contrast of the images to make them pop. When paired with snappy, heartfelt captions, the photos proved irresistible. Hadfield’s online followers skyrocketed from about 20,000 when he went into space to more than 900,000 when he returned.  Many of his images were retweeted thousands of times.

To celebrate the safe return of Expedition 35, I’ve posted fifteen of my favorites below. Thank you, Commander Hadfield, for the remarkable tour.  And welcome home.

BKKlQW6CYAAmILu.jpg_largeTo some this may look like a sunset. But it’s a new dawn. pic.twitter.com/iVgyUihqEN

BBaVLu3CAAAkpnE.jpg_largeAustralia. Jackson Pollock would have been even further inspired by seeing the Outback from orbit. pic.twitter.com/UHtp6lqp

BGPUPVlCcAEzhbh.jpg_large  The Richat Structure. A giant gazing eye upon the Earth. pic.twitter.com/Uqv9JSh17b

BFHNvgbCcAAEyOF.jpg_largeWhen I look at thunderstorms from above, I see faces. What do you see in the clouds? pic.twitter.com/IxSu5XUqGQ

BHm4u6oCEAILfJ5.jpg_largeI have no idea what this Brazilian outcrop looks like on the ground, but from orbit, it’s a brain. pic.twitter.com/QPRcdRGkov

BJxccf-CQAA-p36.jpg_largeSame land, different politics. The US – Mexican border, seen from space. pic.twitter.com/rsEnFX0enN

BKFmjafCIAAWQYz.jpg_largeSpaceships glowing blue in the dawn as we leave Florida headed across the Atlantic. pic.twitter.com/GzEoCg2bb5

BFWax4ICYAEgMEt.jpg_largeCrazed patchwork of farms in Central Asia, a monochromatic 3D hallucination in the snow. pic.twitter.com/PaKYxOn7fg

BHMUeeiCEAAJHox.jpg_largeMorning jet traffic over San Francisco. pic.twitter.com/xgtLVjDD6G

BJnof82CYAEoaDC.jpg_largeOur Sun is immensely, unfathomably powerful. pic.twitter.com/j10CCpP6ya

BHvoL-4CUAEVSeH.jpg_largeWarm brown textures of the Patagonian Andes. pic.twitter.com/GGKgurSQhk

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Seven billion hearts, but I can see only one. #ValentineFromSpace pic.twitter.com/01Lvmkig

BJIsY4ACUAAfrtq.jpg_largeDubai, the Palm Island like a trilobite in the night. pic.twitter.com/RxBHEnSzst

BJVHCWCCIAAGwAD.jpg_largeShadow play of cloud and mountain at sunset. pic.twitter.com/PRggJS7ZOe

BJN2y7kCEAE3KV5.jpg_largeThe Moon ushering in the dawn over the Southeastern United States. pic.twitter.com/i3ETfHP79m

Meet GROVER: NASA’s Rover in Greenland

May 10th, 2013 by María-José Viñas & Adam Voiland

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Not all of NASA’s rovers are headed to Mars. A new Earth science rover nicknamed GROVER started roaming Greenland’s ice sheet this week. The autonomous, solar-operated robot carries a ground-penetrating radar that will be used to examine how snow is accumulating on the Greenland ice pack. Its findings could help scientists understand how the massive ice sheet gains and loses ice.

The GROVER team, led by Goddard Space Flight Center glaciologist Lora Koenig, arrived in Summit Camp, the highest spot in Greenland, on May 6, 2013. After loading and testing the rover’s radar and fixing a minor communications glitch, tests began on the ice on May 8, in spite of winds that blew up to 23 miles (37 kilometers) per hour and temperatures that were as low as -22 degrees Fahrenheit (-30 degrees Celsius).

The tank-like GROVER prototype stands six feet (two meters) tall, including its solar panels. It weighs about 800 pounds and traverses the ice on two repurposed snowmobile tracks. The robot is powered entirely by solar energy, so it can operate in pristine polar environments without adding to air pollution. The panels are mounted in an inverted V, allowing them to collect energy from the sun and sunlight reflected off the ice sheet.

You can track GROVER’s progress by following @NASA_Ice. Read more about GROVER from Climate Central, CBS News, and Discovery News.

Longshot Captures the First Tournament Earth

April 8th, 2013 by Mike Carlowicz

Tournament: Earth 2013 has come to a stunning end. A newcomer to the landscape—a volcano that wasn’t even above the water’s surface at the beginning of 2012—literally came out of nowhere to win our first-ever tournament. The #7 seeded El Hierro submarine eruption from the “events” bracket captured the overall crown.

In a true Cinderella story, the underwater volcano proceeded to knock off four higher seeds before meeting another #7 seed—the crack in the Pine Island Glacier—in the final. The matchup was not even close, as El Hierro romped with 91 percent of the votes.

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Perhaps sensing its impending victory, El Hierro began stirring in late March 2013. According to Erik Klemetti’s “Eruptions” volcanology blog, earthquake swarms beneath the island suggested that magma was on the move. Perhaps a volcano will soon be popping some lava champagne to celebrate the win.

Here is a walk through the opponents that El Hierro tossed aside on it’s month-long romp through earthly fame:

ROUND 1: Overnight View of Hurricane Sandy (#2 seed, events bracket)

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ROUND 2: GOES View of Hurricane Sandy (#3 seed, events bracket)

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ROUND 3: New Volcanic Island in the Red Sea (#5 seed, events bracket)

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ROUND 4: Night Lights 2012 – Flat Map (#2 seed, Earth at night bracket)

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ROUND 5: Flying Through a Crack in the Ice (#7 seed, data bracket)

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Google+ Hangout: Sea Level Rise

April 2nd, 2013 by Adam Voiland

How much and how fast will sea level rise in the coming decades? What makes sea level rise hard to predict? Who will be affected? NASA scientists and guests discussed this and much more in a Google+ Hangout on April 2, 2013. You can watch an archived version of the hangout below.

Hangout participants included:
Josh Willis, NASA’s Jet Propulsion Laboratory
Sophie Nowicki, NASA’s Goddard Space Flight Center
Mike Watkins, NASA’s Jet Propulsion Laboratory
Virginia Burkett, U.S. Geological Survey
Andrew Revkin, Pace University & New York Times Dot Earth blogger

Plus, here’s some background reading on sea level rise.
+NOAA: Sea Level Trends
+NASA Climate Indicator: Sea Level
+Jet Propulsion Laboratory: Sea Level Viewer
+NASA News: What Goes Down Must Come Up
+Earth Observatory: Regional Patterns of Sea Level Change 1993-2007
+Climate Central: Surging Seas
+National Geographic: Sea Level Rise
+New York Times: Sea Level and the Limits of the Bathtub Analogy
+Los Angeles Times: Most in U.S. Concerned about Sea Level Rise, Poll Finds