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Earth Matters

Introducing Landsat Ice Stream (73°36′S, 79°03′W)

June 18th, 2019 by Laura Rocchio, Landsat Communication and Public Engagement Team

The UK’s Antarctic Place-names Committee has agreed that seven ice features in western Antarctica should be named for Earth-observation satellites. One of them is Landsat Ice Steam. 

The new designations were announced on June 7, 2019. The ice features are all located in Western Palmer Land on the southern Antarctic Peninsula.

The seven features ring George VI Sound like pearls on a necklace. The new names, as officially entered into the British Antarctic Territory Gazetteer, are (from west to east): Landsat Ice Steam, ALOS Ice Rumples, Sentinel Ice Stream, GRACE Ice Stream, Envisat Ice Stream, Cryosat Ice Stream, and ERS Ice Stream.

The UK has submitted the new names for the fast-moving ice features to Scientific Committee on Antarctic Research (SCAR), which maintains a gazetteer or registry, of names officially adopted by individual nations. Under the Antarctic Treaty, signatory nations confer on geographic feature names, but each nation’s naming authority formally adopts new names. The U.S. Board on Geographic Names will meet in July and may discuss at that meeting whether the names adopted by the UK also will be adopted by the US. The question of using the term “glacier” for the ice features instead of “ice stream” is also part of each nation’s naming decision.

The new names were proposed by Anna Hogg, a glaciologist with the Center for Polar Observation and Modelling at the University of Leeds. In research published in 2017, Hogg found that glaciers draining from the Antarctic Peninsula were accelerating, thinning, and retreating, with implications for global sea level rise. The fast-moving glaciers that Hogg and colleagues tracked with radar and optical satellite imagery were unnamed. In her paper, the glaciers had to be designated by latitude and longitude.

Anna Hogg, glaciologist from the University of Leeds, proposed naming Antarctic ice features for satellites.

Satellites had enabled Hogg and her team to clock the speed of these nameless ice features—some with rates faster than 1.5 meters/day. In tribute to the spaceborne instruments, Hogg came up with a way to describe the fast-moving ice features more succinctly—name them after the satellites that had helped her understand their behavior.

Hogg proposed to the U.K.’s Antarctic Place-names Committee that the features should be named for Landsat, Sentinel, ALOS PALSAR, ERS, GRACE, CryoSat, and Envisat. She was notified in early June that the committee had agreed to adopt the names, which provide a way to recognize international collaboration, as fifteen space agencies currently collaborate on Antarctic data collection.

“Satellites are the heroes in my science of glaciology,” Hogg told the BBC. “They’ve totally revolutionized our understanding, and I thought it would be brilliant to commemorate them in this way.” 

Naming the glaciers after satellites is also a celebration of data fusion. “Our understanding of ice velocities and ice sheet mass balance has come from putting many different remote sensing data sets together—optical, radar, gravity, and laser altimetry,” said Jeff Masek, the NASA Landsat 9 Project Scientist. “Landsat has been a key piece in assembling that larger puzzle. Naming an ice stream after Landsat is a fitting way to recognize the value of long-term Earth Observation data for measuring changes in Earth’ polar regions.”

Read more from NASA’s Landsat science and outreach team, including the history of Antarctic observation with Landsat. Read more about all of the glaciers and their namesake satellites, as told by the European Space Agency. And read about the island discovered by and named for Landsat, and the woman who discovered it.

Correction, June 27, 2019: SCAR’s role in the Antarctic naming process was incorrectly described in the earlier version of this article. Updates were provided by Dr. Scott Borg, Deputy Assistant Director of the National Science Foundation’s Directorate for Geosciences, and Peter West, the Outreach Program managers for NSF’s Office of Polar Programs, to correctly describe the naming process.

Landsat 8 acquired this image of Mauna Loa on December 20, 2014. The CO2 observatory is located just north of the summit caldera. Credit: NASA Earth Observatory/Landsat 8. Learn more about the image here.

If you follow science news, this will probably sound familiar.

In May 2019, when atmospheric carbon dioxide reached its yearly peak, it set a record. The May average concentration of the greenhouse gas was 414.7 parts per million (ppm), as observed at NOAA’s Mauna Loa Atmospheric Baseline Observatory in Hawaii. That was the highest seasonal peak in 61 years, and the seventh consecutive year with a steep increase, according to NOAA and the Scripps Institution of Oceanography.

The Mauna Loa Observatory has been measuring carbon dioxide since 1958. The remote location (high on a volcano) and scarce vegetation make it a good place to monitor carbon dioxide because it does not have much interference from local sources of the gas. (There are occasional volcanic emissions, but scientists can easily monitor and filter them out.) Mauna Loa is part of a globally distributed network of air sampling sites that measure how much carbon dioxide is in the atmosphere.

Global concentrations of atmospheric carbon dioxide spike every April or May, but in 2019 the spike was bigger than usual. The dashed red line represents the monthly mean values; the black line shows the same data after the seasonal effects have been averaged out. Credit: NOAA. Read more about the image here.

The broad consensus among climate scientists is that increasing concentrations of carbon dioxide in the atmosphere are causing temperatures to warm, sea levels to rise, oceans to grow more acidic, and rainstorms, droughts, floods and fires to become more severe. Here are six less widely known but interesting things to know about carbon dioxide.

The rate of increase is accelerating.

For decades, carbon dioxide concentrations have been increasing every year. In the 1960s, Mauna Loa saw annual increases around 0.8 ppm per year. By the 1980s and 1990s, the growth rate was up to 1.5 ppm year. Now it is above 2 ppm per year. There is “abundant and conclusive evidence” that the acceleration is caused by increased emissions, according to Pieter Tans, senior scientist with NOAA’s Global Monitoring Division.

Credit: NOAA/Scripps Institute of Oceanography. Read more about the chart here.


Scientists have detailed records of atmospheric carbon dioxide that go back 800,000 years.

To understand carbon dioxide variations prior to 1958, scientists rely on ice cores. Researchers have drilled deep into icepack in Antarctica and Greenland and taken samples of ice that are thousands of years old. That old ice contains trapped air bubbles that make it possible for scientists to reconstruct past carbon dioxide levels. The video below, produced by NOAA, illustrates this data set in beautiful detail. Notice how the variations and seasonal “noise” in the observations at short time scales fade away as you look at longer time scales.

CO2 is not evenly distributed.

Satellite observations show carbon dioxide in the air can be somewhat patchy, with high concentrations in some places and lower concentrations in others. For instance, the map below shows carbon dioxide levels for May 2013 in the mid-troposphere, the part of the atmosphere where most weather occurs. At the time there was more carbon dioxide in the northern hemisphere because crops, grasses, and trees hadn’t greened up yet and absorbed some of the gas. The transport and distribution of CO2 throughout the atmosphere is controlled by the jet stream, large weather systems, and other large-scale atmospheric circulations. This patchiness has raised interesting questions about how carbon dioxide is transported from one part of the atmosphere to another—both horizontally and vertically.

The first space-based instrument to independently measure atmospheric carbon dioxide day and night, and under both clear and cloudy conditions over the entire globe, was the Atmospheric Infrared Sounder (AIRS) on NASA’s Aqua satellite. Read more about this image here. The OCO-2 satellite, launched in 2014, also makes global measurements of carbon dioxide, and it does so at even lower in the atmosphere than AIRS.

Despite the patchiness, there is still lots of mixing.

In this animation from NASA’s Scientific Visualization Studio, big plumes of carbon dioxide stream from cities in North America, Asia, and Europe. They also rise from areas with active crop fires or wildfires. Yet these plumes quickly get mixed as they rise and encounter high-altitude winds. In the visualization, reds and yellows show regions of higher than average CO2, while blues show regions lower than average. The pulsing of the data is caused by the day/night cycle of plant photosynthesis at the ground. This view highlights carbon dioxide emissions from crop fires in South America and Africa. The carbon dioxide can be transported over long distances, but notice how mountains can block the flow of the gas.

Carbon dioxide peaks during the Northern Hemisphere spring.

You’ll notice that there is a distinct sawtooth pattern in charts that show how carbon dioxide is changing over time. There are peaks and dips in carbon dioxide caused by seasonal changes in vegetation. Plants, trees, and crops absorb carbon dioxide, so seasons with more vegetation have lower levels of the gas. Carbon dioxide concentrations typically peak in April and May because decomposing leaves in forests in the Northern Hemisphere (particularly Canada and Russia) have been adding carbon dioxide to the air all winter, while new leaves have not yet sprouted and absorbed much of the gas. In the chart and maps below, the ebb and flow of the carbon cycle is visible by comparing the monthly changes in carbon dioxide with the globe’s net primary productivity, a measure of how much carbon dioxide vegetation consume during photosynthesis minus the amount they release during respiration. Notice that carbon dioxide dips in Northern Hemisphere summer.

Credit: NASA Earth Observatory. Read more about this image here.

It isn’t just about what is happening in the atmosphere.

Most of Earth’s carbon—about 65,500 billion metric tons—is stored in rocks. The rest resides in the ocean, atmosphere, plants, soil, and fossil fuels. Carbon flows between each reservoir in the carbon cycle, which has slow and fast components. Any change in the cycle that shifts carbon out of one reservoir puts more carbon into other reservoirs. Any changes that put more carbon gases into the atmosphere result in warmer air temperatures. That’s why burning fossil fuels or wildfires are not the only factors determining what happens with atmospheric carbon dioxide. Things like the activity of phytoplankton, the health of the world’s forests, and the ways we change the landscapes through farming or building can play critical roles as well. Read more about the carbon cycle here.

Seven million years ago, some truly spectacular creatures roamed the woodlands of East Africa. There was a moose-like giraffe called Shiva’s beast. There were giant buffalo with horns wider than the animals were tall. And the lumbering creatures known as anthracotheres defy easy categorization.

“Whenever I ask colleagues who study anthracotheres how they describe them, they always say: hippo-pig,” laughed Tyler Faith, curator of archaeology at the Natural History Museum of Utah. As for the buffalo: “This was a horn span of 3 meters (10 feet). I mean this was an awesome buffalo.”

Image credit: Slide courtesy of Tyler Faith

These and several dozen variations of more recognizable African megaherbivores — elephants, rhinos, hippos, and giraffes — all went extinct within the past several million years. For decades, archaeologists have pinned the blame on early humans, particularly Homo erectus, a species that emerged 2 million years ago, walked upright, and had a body plan similar to modern humans. Since Homo erectus made stone weapons and was capable of butchering large game, many archaeologists assumed that it hunted Africa’s megaherbivores into extinction — much like the fossil record suggests Homo sapiens (modern humans) did to the large mammals of North and South America some 11,000 years ago.

But nobody rigorously tested whether this “overkill hypothesis” fit with the fossil record. “Speculation had been repeated often enough that it just graduated into fact; it became the truth,” Tyler explained during a recent colloquium at NASA’s Goddard Space Flight Center. To check more rigorously, Tyler and colleagues analyzed fossil assemblages from 101 sites in Eastern Africa.

Image credit: Slide courtesy of Tyler Faith

What they found was a surprise. Megaherbivores began disappearing about 4.6 million years ago — long before Homo erectus came on the scene (1.8 million years ago). And there was no increase in the rate of extinctions even when Homo erectus and butchering showed up in fossil records.

However, when the researchers looked at some key indicators of past environmental conditions, they found one key change — the expansion of grasslands — lined up with the extinctions almost perfectly. Five million years ago, classic open grasslands like today’s Serengeti Plain did not exist in East Africa. Trees and shrubs were a much more dominant part of that African landscape then, explained Tyler.

But as carbon dioxide levels declined, mainly due to orbital variations and changes in the amount of Earth covered by ice, forests retreated and grasslands became dominant. Since many of the megaherbivores fed mainly on woody vegetation, they likely faded away along with their food sources. Meanwhile, other familiar species thrived. The ancestors of wildebeest, hartebeests, Thompson gazelles, oryx, plains zebras, and warthogs — all grazers that live in open habitats — proliferated.

Grasslands dominate northern Tanzania’s Serengeti Plain. The first image shows withered grasslands during a drought. The second image shows the same area during a wetter year. Read more about these images. Credit: NASA Earth Observatory

Faith’s bottom line is that it is time to stop blaming Homo erectus for something they didn’t do. “In the search for ancient hominid impacts on ancient African ecosystems, we must focus our attention on the one species known to be capable of causing them – us, Homo sapiens, over the past 300,000 years,” he said.

Faith’s analysis found that megaherbivore diversity started to decline well before Homo erectus emerged. Image credit: Faith et al.

Follow Lewis and Clark as a Citizen Scientist

May 30th, 2019 by Maria-Jose Viñas

In the early 19th century, Meriwether Lewis and William Clark led an ambitious expedition across the western United States. They greatly expanded our knowledge of the country’s geography and biological diversity through their specimen collection, mapping of the landscape, and detailed journal entries.

This year NASA and the National Park Service are encouraging the public to follow in the footsteps of Lewis and Clark through a new citizen science challenge. From June 1 to September 2, citizens are invited to use their smart phones and the NASA GLOBE Observer app to map land cover along the Lewis and Clark National Historic Trail to assist scientists studying environmental changes.

Land cover–such as grass, pavement, or trees–influences the water and energy cycles and influences a community’s vulnerability to natural disasters. NASA studies land cover changes from space as part of its mission to better understand our planet and improve lives.

These “observation station” stickers–located at many of the museums and visitor centers along the Lewis and Clark National Historic Trail–indicate places where repeat observations are needed to verify the accuracy of citizen science data.

To participate in the “GO on a Trail” challenge, download the free GLOBE Observer app from the Apple App Store or Google Play. Use the Land Cover tool to make observations of the landscape. Any observation made along the 5,000-mile-long Lewis & Clark trail from Pittsburgh to the mouth of the Columbia River earns points. The top participants will receive recognition and GO on a Trail commemorative material.

A good place to get started is at an observation station marked with a large sticker (image above) at Lewis and Clark visitor centers and museums. To navigate to sites of interest along the trail, the Lewis and Clark National Historic Trail and GLOBE Observer teams have provided an online map.

“We hope that by becoming involved with this project, people will care about the trail and become its stewards,” said Dan Wiley, chief of integrated resource stewardship for the Lewis and Clark National Historic Trail. Wiley notes that the challenge will both spark a general interest in science and show the public how it can be involved in collecting vital information for decision makers.

In July 1804, the Lewis & Clark Expedition paused to rest and repair their boats and planned the “first” Native American council (Council Bluff) with representatives of the Otoe Tribe.

GLOBE Observer is an app-based citizen science program active in more than 120 countries. The program invites citizens to contribute land cover, cloud, mosquito, and tree height observations to NASA and the science community. NASA-funded scientists are eager to see citizen science observations of land cover along this trail because of its wide range of ecological regions. Data collected during the challenge could help improve satellite-based mapping of land cover across the continent. 

“We are observing and monitoring our changing home planet from space to better understand how it is changing and what are the main drivers of change,” said Eric Brown de Colstoun, a scientist at NASA Goddard Space Flight Center. “The view from the ground provided by the challenge participants is one component that helps us verify the space-based data.”

In September 1805, the 29-person “Corps of Discovery” crossed the Bitterroot Mountains (shown above) along the Lolo Trail—one of the most arduous portions of the 28-month journey from St. Louis to the Pacific Ocean and back.

Even if you are not able to visit the Lewis and Clark Trail this summer, you can still join the GO on a Trail challenge from any of the more than 120 countries where GLOBE Observer is active. Just get outdoors and map the land cover around you. The top participants from beyond the trail will also receive recognition and commemorative material.

“Lewis and Clark and their team were exploring a totally new environment to them,” said Brown de Colstoun. “We invite you to get out and explore, and document the places you know and care about. Go on a trail and do science along with us.”

NASA GLOBE Observer and Lewis and Clark National Historic Trail will provide regular updates about the GO on a Trail challenge via social media throughout the summer with the hashtag #GOonaTrail. Follow GLOBE Observer on Facebook @nasa.globeobserver or Twitter @NASAGO. Follow the Lewis and Clark National Historic Trail on Facebook @lewisandclarknht, Twitter @lewisclarktrail, and Instagram @lewisandclarknht or visit the website at: https://www.nps.gov/lecl/index.htm.

It Was 20 Years Ago Today…

April 29th, 2019 by Mike Carlowicz

On April 29, 1999, NASA Earth Observatory (EO) started delivering science stories and imagery to the public through the Internet. So much has changed in those 20 years…

+ In 1999, about 3 to 5 percent of the world had Internet access. About 41 percent of American adults used the World Wide Web, most often to look at the weather. Today an estimated 56 percent of the world’s population (4.3 billion people) are active on the Internet. 

+ At the end of the 20th century, all EO readers came to us through a computer, mostly desktops. One third of them were connecting via dial-up modem. Today, about 40 percent of our audience arrives to the web site via mobile phones and tablets on public wifi and cellular networks. Yet even now, 65,000 of our most loyal followers subscribe to our newsletters. Many others subscribe to our RSS feeds.

The site has had five different designs over the decades.

+ In 1999, “social” media mostly consisted of chatrooms and newsgroups. Even by 2005, only 5 percent of Americans were using social media. Today about 69 percent of adults use social media, and people are just as likely to see Earth Observatory content on social platforms as on our web site. Ten million people follow EO and NASA Earth science on Facebook, with 1.3 million more on Twitter, and 500,000 on Instagram.

+ When EO launched, images from Earth science satellites were generally available about a month after acquisition. Public access to science data and imagery was extremely limited, highly filtered, and sometimes required a fee. Two decades later, many NASA Earth science observations are available freely on the web within hours of acquisition.

+ On our first day online, the site got 400 pageviews–most of them were likely colleagues and relatives. Today we get about 50,000 views per day.

Our baby portrait from 1999.

+ In our first year, we published 35 “Images of the Week” and 9 feature stories. By 2001, we started delivering an Image of the Day. Since launch, we have published more than 6,900 Images of the Day, 8,300 natural hazards images, and 450 features and videos. Yes, more than 15,000 image-driven stories, and all of them are still available in our archive.

+ In 1999, two members of our staff were in elementary school and three were in high school. The readers of EO Kids were not born yet.

The technology of science and the Internet has changed in a generation, and our site has evolved and grown with the changes. But our core values have not changed. You find us on more platforms and with some new approaches, but you can still count on us to deliver beautiful, newsworthy, interesting, and scientifically important images and stories. Our editorial team has more than 110 years of experience in science communication and data visualization, and we bring that depth of knowledge to every story, 365 days a year.

None of this would be possible without the many scientists, engineers, communicators, data hounds, patrons, and friends inside and outside of NASA who review our work, tip us off to stories and images, share their scientific insights, and inspire and challenge us. Thank you.

You can view a daily “greatest hit” from our archives at the On This Day page.

As we celebrate our 20th year, we are going to share some looks back and some looks ahead. In the next twelve months, look for…

  • EO on This Day – a chance to see some of the most memorable Images released on each day of the calendar year
  • New puzzlers, videos, and social media events
  • Stories of science evolving, as we revisit images, global maps, and science stories from the past 20 years and ask “what have we learned in two decades and where do we go next?”
  • Our first photo essay book, available in print, on the web, or downloadable to your tablet.

If you have been with us for many (or all) of our 20 years, thank you. We have some of the most engaged, challenging, and thoughtful readers on the planet, and we work hard to live up to your trust and interest. If you are new to the site, bring a friend. We have 15,000 stories about Earth to share, with more being added every day.

Related Links and References

Earth Observatory 10th Anniversary

Pew Research Center (2018)  World Wide Web Timeline

Internet World Stats (2019)  Internet Growth Statistics

Wikipedia (2019) Global Internet Usage

Picture Earth for Earth Day

April 18th, 2019 by NASA Earth Science Communications Team

For Earth Day 2019, NASA invites you to celebrate the planet we call home with our #PictureEarth social media event.

NASA studies Earth as part of its mission. Our satellites and instruments #PictureEarth daily. Some take visible light photos, much like your camera. Others peer into the infrared, microwave, ultraviolet, or radio spectrums, which human eyes cannot see. Each satellite image or data set reveals a small detail of the land, water, atmosphere, and life on Earth.

Four global views illustrate how NASA satellites and instruments #PictureEarth daily. From left to right, average precipitable water vapor; monthly average sea level variation; average daytime air temperature; root zone soil moisture.

How do you #PictureEarth?

Show NASA how you see your planet by posting photos on social media. Focus on the details around you with close-up images.

What makes your location special? 

What are the textures, colors, or patterns in your surroundings? 

Look for Earth’s dynamism, motion, and beauty: blooming flowers, crashing waves, sturdy trees, furry and feathered animals, molten lava, puffy clouds, smooth ice, and warm sunlight.

These photos of plants, animals, insects, and the atmosphere, land and water were taken by NASA employees and provide examples of how to #PictureEarth for Earth Day 2019.

Share your best Earth photo!

On Earth Day — April 22, 2019 — share your best photos of Earth on social media with the hashtag #PictureEarth. Be sure to tell us where your photo was taken. We love to read posts from around the world because NASA Earth data is available to everyone – we all live on this planet together.

We’ll be watching on Instagram, Twitter, and our Facebook event page for your images and messages. As with our previous Earth Day events, we’ll select some of the publicly-shared photos to showcase in videos and composite images featuring your beautiful imagery.

Then download the NASA Earth photo book

To see how we #PictureEarth from space, download the new Earth photo book or read it online: https://earthobservatory.nasa.gov/features/earth-book-2019

Landsat 7 Turns 20

April 16th, 2019 by Laura Rocchio

On April 15, 1999, Landsat 7 first made its way into space. 106,380 orbits later, the 2.6 million images acquired by Landsat 7 have given us a fuller and more nuanced understanding of Earth.

Landsat 7 launched from Vandenberg Air Force Base in California on April 15, 1999. Photo credit: NASA

Take for example the Millennium Coral Reef Mapping Project. In 2006, Landsat 7 data were used to create a first-of-its kind global survey of coral reefs. The research lead on this project, Frank Muller-Karger, commented in 2015: “Until we made the map of coral reefs with Landsat 7, global maps of reefs had not improved a lot since the amazing maps that Darwin drafted.”

Landsat 7 data, together with data from its predecessor Landsat 5, provided the most comprehensive assessment ever of Earth’s mangroves in 2010.

And for the International Polar Year (2007-2008), data from more than 1,000 Landsat 7 images were used to create the Landsat Image Mosaic of Antarctica (LIMA)—what was then the most detailed satellite mosaic of Antarctica.

Here the LIMA data set shows Antarctica’s Ferrar Glacier (at 15 meters per pixel).

If we travel two decades back in time and rewind the 4,733,375,587.686 kilometers that Landsat 7 has flown since April 1999, we arrive at a very different moment in spaced-based Earth observation.

The commercially-owned Landsat 6 satellite had failed to reach orbit six years earlier. Landsat 5 was 12 years past its design life and operated by a for-profit entity that charged upwards of $4000 per image and collected international data only when there was an immediate customer. Both situations curtailed the systematic global coverage of Earth that had been envisioned by the Landsat Program’s founders.

A building consensus about the critical role of Earth observation data for global change research had led the National Space Council to recommend that Landsat 7 be built. It should be operated by the U.S. government to ensure a continuous global archive of medium-resolution data for the long-term monitoring of Earth’s land surface. This was codified with the 1992 U.S. Land Remote Sensing Policy Act.

When Landsat 7 launched on April 15, 1999, the Enhanced Thematic Mapper Plus (ETM+) instrument onboard was the most sophisticated Landsat sensor yet. ETM+ carried a new 15-meter panchromatic band and had a thermal band with a spatial resolution refined to 60 meters (compared to 120 meters for Landsat 4 and 5). It also carried a new solid-state data recorder—one of the first to fly on a civilian mission. For the first time in Landsat program history, Landsat 7 was equipped with hardware that could reliably store large amounts of imaged data onboard for later download when a ground station was in range.

A natural color Landsat 7 image of the extensive coral reefs on the northern shore of Vanua Levu, Fiji’s second largest island (acquired on September 19, 2002).

Landsat 7’s state-of-the-art recorder, together with a strategic global image acquisition plan, enabled the best global coverage the program had ever known. The LIMA project lead, Robert Bindschadler, penned in a 2001 journal article that “The revolutionary concept of systematic collection of Landsat 7 data timed to optimize anticipated scientific applications will make possible a global monitoring of the cryosphere with a data set heretofore only available in limited regions.”

During its ascent into orbit in 1999, Landsat 7 collected data as it flew under Landsat 5. This enabled the cross-calibration of Landsats 5 and 7. (In 2013, Landsat 8 underflew Landsat 7 for the same reason). Additionally, a team of calibration scientists oversaw in-the-field calibration efforts, making certain that satellite measurements agree with physical ground measurements. Such careful data calibration ensures that the Landsat data record can show meaningful trends of land use and land cover change—even when the changes are subtle.

Landsat 7 has enabled many firsts when it comes to global studies. The Giri et al. mangrove map is one such example.

In May 2003, an image scanning mechanism on Landsat 7 (the Scan Line Corrector) failed, leaving wedge-shaped gaps in the imagery—a net loss of 22 percent of each image. As devastating as this failure was, the remaining data are, as USGS describes, “some of the most geometrically and radiometrically accurate of all civilian satellite data in the world.”

The landmark 2008 USGS decision to make all Landsat data free and open, and the subsequent trend towards best-pixel composite-based data analysis, has made these data gaps even less problematic.

All in all, Landsat 7 has made remarkable contributions to global studies for two decades now, and according to fuel-based predictions, it should be able to continue doing so until the launch of Landsat 9.

Did you know?

In the second it took you to read this line, Landsat 7 traveled about 7.499 kilometers.

The launch of Landsat 7 was the second image ever posted on NASA Earth Observatory.

The Landsat 7 Mission Operations Control Center is staffed by 14 engineers, seven days a week, 8 hours a day. Someone is always on call and ready to respond if a ground or spacecraft anomaly occurs. 

References:
Goward, S.N. et al. (2017) Landsat’s Enduring Legacy: Pioneering Global Land Observations from Space. Bethesda, MD: American Society for Photogrammetry and Remote Sensing.

Wulder, M.A. et al. (2019) “Current status of Landsat program, science, and applications.”  Remote Sensing of Environment 225:127-147.

Science for the Peeple

March 21st, 2019 by Kasha Patel
Photo credit: Kate Ter Haar / Flickr via Creative Commons

What do you get when you mix science with sugary marshmallow candy? Peepola Tesla, the candy bunny that invented the transmitter. Or Neanderpeeps, the group of sweet marshmallows that created fire. Or Dmitri Mendelpeep, the father of the peepiodic table.

For the first time possibly ever, science writers, school children, and enthusiastic science fans participated in “The World’s Finest Science-Themed Peeps Diorama Contest.” Participants were asked to recreate scenes of scientific discoveries, field work, moments in history, and model organisms— all made with the spring marshmallow treats. With nearly 50 entries to choose from, you now get to vote on which diorama deserves the coveted “Peeple’s Choice Award.”

Of course here at NASA Earth Observatory, we are partial to the space- and Earth-themed dioramas. Take a peep at some of the entries below. Make sure to vote for your favorite here before April 14, 2019.


Scientists Peep Satellite Data to Save the Peep-guins

Credit: Sarah Frazier, Katy Mersmann / The Open Notebook

Antarctic peep-searchers use Landsat images of peep-guin peep (er, poop) to measure the health of colonies. Penguin peep (er, poop) is bright pink and bright blue, depending on if they’re eating shrimp or sardines. What they’re eating and how much peep (er, poop) is on the ice is an important indicator of peep-guin health. In this diorama, intrepid peep-searchers are bundled up in their cozy Arctic gear, visiting the peep-guin colony from a peep-search ship to ground-truth the colony counts they’re getting with satellite data. Reminder to all peep-searchers: Don’t eat the pink snow!

Read about the original research on NASA Earth Observatory.


New Hare-rizons: Ultima Peep Flyby

Credit: Emily Conover / The Open Notebook

Peep scientists are investigating an unusual object at the far reaches of the solar system, known as Ultima Peep. The spacecraft New Hare-rizons is closing in, and images of Ultima Peep are becoming clearer. At first, Ultima Peep appeared to be shaped like a bowling pin, but now, some are beginning to suspect that Ultima Peep is shaped like a peep. (Perhaps it is a lonely space peep?) The peeple demand information! Scientists have called a press conference to weigh in, and journalists are peepering them with questions.

The scientific inspiration for this diorama is, of course, NASA’s New Horizons spacecraft and its investigation of the Kuiper Belt object Ultima Thule, the shape of which became clearer as the spacecraft got closer. Unfortunately, in our world, bunny ears never materialized. The diorama also includes a title and a close-up of the encounter between New Hare-rizons and Ultima Peep.

Read about the Ultimate Thule flyby.


Hidden Peeps

Credit: Ella Theoharis, Jeanne Theoharis, George Theoharis & Sam Theoharis / The Open Notebook

Hidden Peeps is an artistic rendering of the Black women who made essential contributions to the U.S. scientific space program at NASA. The right side of the diorama depicts the women, known as computers, whose work enabled US spaceflights but went largely unsung.  The details include Dorothy Vaughan programming an early computer, Katherine Johnson and Mary Jackson writing their official technical reports, other women doing math on the chalkboard, calculating trajectories, verifying fight patterns. Be sure to check out the ‘colored’ bathroom sign (NASA’s facilities in Virginia were segregated), the Mary Jackson quote, the women’s glasses, typewriter, pencils, coffee mugs and family peeps photo.

The other side of the diorama depicts the men receiving attention and accolades for the space program complete with astronaut John Glenn in the rocket, military band, NBC photographer, and medals.  Check out the NASA logo and the Neil Armstrong-inspired banner, “One small hop for Peeps….”

Learn more about NASA’s Hidden Figures and Modern Figures.


Apeepllo 11 at Tranquilipeep Base

Credit: Lauren Morello / The Open Notebook

Astropeeps Bunny Aldrin and Neil Peepstrong explore Tranquilipeep Base — making history as the first sentient marshmallows to step on the moon. Marshmallow Collins drew the short straw and is orbiting up high in the Columbia capsule.

Meanwhile, Bunny is collecting rock samples with his shovel and sample box, and Neil takes pictures with his hand-held camera. The two astropeeps have already planted the American flag, and their ride — the Eagle lander — waits in the distance. They keep their spacesuits on, because bad things happen to Peeps in a vacuum…

See the photograph taken by Neil Armstrong of the Lunar Module at Tranquility Base.


Peepil Armstrong – First Peep on the Moon

Credit: Mrs. Tamblyn’s Class (Team SM) / The Open Notebook

Peepil Armstrong takes his first hop on the moon.

View the original video of Neil Armstrong walking on the moon.


To The Moon? Nein! To Mars, My Peeps!

Credit: Cassondra Windwalker, Thomas Klingensmith / The Open Notebook

Wernher Von Braun’s V2 rockets ultimately powered the Saturn V and took the United States to the moon, but von Braun always saw Mars as the true destination. Today, we are proving him right. So while the crowds have their eyes on the moon, von Braun points the way to Mars.

Learn about NASA’s mission to Mars.


The contest is hosted by The Open Notebook, a non-profit publication aimed to help science journalists sharpen their skills by providing useful tools, articles, and career advice.  The contest is the brainchild of volunteers Joanna Church, Helen Fields, and Kate Ramsayer, an award-winning trio of peep diorama makers from the Washington, DC, area.

Beyond the Galapagos with Darwin

February 12th, 2019 by Adam Voiland

On February 12, 1809, Charles Robert Darwin was born in England in the town of Shrewsbury. The famed naturalist, geologist, and biologist is best known for his 19th century expedition to the Galápagos Islands, which inspired revolutionary insights about evolution and natural selection. Lesser known is that the expedition to the Galápagos was just one part of a much longer journey. The Second Voyage of the HMS Beagle brought Darwin and his fellow travelers to South America, Australia, Africa, and several islands in between. Here are a few interesting places where the HMS Beagle stopped that we have covered in earlier stories.

January 1832: The Dusty Canary Islands, Tenerife

Read more about this Landsat 8 image.

The crew of the Beagle was denied landing on Tenerife because of fears they might be carrying cholera. The Operational Land Imager (OLI) on Landsat 8 acquired this image of the island on January 25, 2016.

Darwin was struck by the intensity of the dust in this area. “The atmosphere is generally very hazy, chiefly due to an impalpable dust, which is constantly falling, even on vessels far out at sea,” he wrote. “It is produced, as I believe, from the wear and tear of volcanic rocks, and must come from the coast of Africa.”

Read more about this Terra image.

Christmas 1832: Cape Horn, South America

Read more about this Landsat 8 image.

Southwest of Cape Horn at the southern tip of South America, the ocean floor rises sharply. Along with the potent westerly winds that swirl around the Furious Fifties, this pushes up massive waves with frightening regularity. Add in frigid water temperatures, rocky coastal shoals, and stray icebergs—which drift north from Antarctica across the Drake Passage—and it is easy to see why the area is known as a graveyard for ships. In his journal, Darwin described the harrowing journey as the explorers tried to round the Horn just before Christmas.

“Great black clouds were rolling across the heavens, and squalls of rain, with hail, swept by us with such extreme violence, that the Captain determined to run into Wigwam Cove. This is a snug little harbor, not far from Cape Horn; and here, at Christmas-eve, we anchored in smooth water. The only thing which reminded us of the gale outside, was every now and then a puff from the mountains, which made the ship surge at her anchors.”

Charles Darwin
Read more about this astronaut photograph.

September 1835: The Galapagos

The Galapagos archipelago includes more than 125 islands, islets, and rocks populated by a diversity of wildlife. Charles Darwin’s book, The Voyage of the Beagle, cast a spotlight on the Galapagos, which he called “a little world within itself, or rather a satellite attached to America, whence it has derived a few stray colonists.” It was this little world that would revolutionize scientific understanding of biology and lead to Darwin’s On the Origin of Species, which would come to be known as the foundation of evolution.

Read more about this Aqua image.

November 1835: The Coral Reefs of Tahiti

On this stopover, Darwin had a chance to explore coral reef.

“We paddled for some time about the reef admiring the pretty branching Corals,” he wrote. “It is my opinion, that besides the avowed ignorance concerning the tiny architects of each individual species, little is yet known, in spite of the much which has been written, of the structure and origin of the Coral Islands and reefs.”

The Enhanced Thematic Mapper Plus on the Landsat 7 satellite captured this natural-color image of Tahiti on July 11, 2001. This island is part of a volcanic chain formed by the northwestward movement of the Pacific Plate over a fixed hotspot.

Read more about this Landsat 7 image.

1836: Pondering Phytoplankton Near Australia

All the sea travel offered plenty of time to observe and ponder the intricacies of phytoplankton.

“My attention was called to a reddish-brown appearance in the sea. The whole surface of the water, as it appeared under a weak lens, seemed as if covered by chopped bits of hay, with their ends jagged,” he wrote. “These are minute cylindrical, in bundles or rafts of from twenty to sixty in each…Their numbers must be infinite: the ship passed through several bands of them, one of which was about ten yards wide, and, judging from the mud-like color of the water, at least two and a half miles.”

On August 9, 2011, the Moderate Resolution Imaging Spectroradiometer (MODIS) on the Aqua satellite captured this image of a similar band of brown between the Great Barrier Reef and the Queensland shore. Though it’s impossible to identify the species from satellite imagery, such red-brown streamers are usually trichodesmium. Sailors have long called these brown streamers “sea sawdust.”

Read more about this Aqua image.

Astronauts Photograph Brazil Mine Tailings Disaster

February 12th, 2019 by Adam Voiland

A few days after we published a Landsat 8 image of a deadly dam collapse and flood in Brazil, astronauts photographed the scene from the International Space Station on February 2, 2019.

The tailings pond label points to the source of the mine waste. When an earthen dam on the southwestern edge of that pond collapsed on January 25, it sent a torrent of sludge pouring down a valley toward the Paraopeba River. Over a distance of roughly 8 kilometers (5 miles), the mine sludge overran the mine’s headquarters, a hotel, and a residential area. Videos published by news agencies and AGU’s Landslide Blog offer a remarkable view of the dam collapsing and sludge rushing forward at roughly 120 kilometers (75 miles) per hour.

NASA’s Earth Science Disasters Program has developed an interactive version of the astronaut photograph that allows you to explore the area before and after the disaster. More astronaut photos of the event are available here.