The rate at which Greenland is losing its ice is accelerating. This unsurprising conclusion comes from a new study based on 25 years of satellite data from the European Space Agency. The new study was published in Earth and Planetary Science Letters. Continue reading “Ice loss in Greenland is Accelerating”
Nothing lasts forever, especially an iceberg drifting away from its frigid home. This coffin-shaped iceberg was spotted by astronauts on the International Space Station as it drifted northwards. It split off from a much larger iceberg about 18 years ago, and is moving into warmer and warmer waters.
Arctic sea ice is getting thinner and younger. Satellite data and sonar records from submarines show how the ice coverage in the north is getting more and more seasonal. In the past, ice would build up year over year, getting thicker and stronger. But seasonal ice disappears each summer, meaning more open ocean in the summer, and less of the Sun’s energy being reflected back into space.
Stand outside and take deep breath. Do you know what you’re breathing? For most people, the answer is simple – air. And air, which is essential to life as we know it, is composed of roughly twenty-percent oxygen gas (O²) and seventy-eight percent nitrogen gas (N²). However, within the remaining one-percent and change are several other trace gases, as well as few other ingredients that are not always healthy.
NASA’s Earth Observatory is a vital part of the space agency’s mission to advance our understanding of Earth, its climate, and the ways in which it is similar and different from the other Solar Planets. For decades, the EO has been monitoring Earth from space in order to map it’s surface, track it’s weather patterns, measure changes in our environment, and monitor major geological events.
For instance, Mount Sinabung – a stratovolcano located on the island of Sumatra in Indonesia – became sporadically active in 2010 after centuries of being dormant. But on February 19th, 2018, it erupted violently, spewing ash at least 5 to 7 kilometers (16,000 to 23,000 feet) into the air over Indonesia. Just a few hours later, Terra and other NASA Earth Observatory satellites captured the eruption from orbit.
The images were taken with Terra’s Moderate Resolution Imaging Spectroradiometer (MODIS), which recorded a natural-color image of the eruption at 11:10 am local time (04:10 Universal Time). This was just hours after the eruption began and managed to illustrate what was being reported by sources on the ground. According to multiple reports from the Associated Press, the scene was one of carnage.
According to eye-witness accounts, the erupting lava dome obliterated a chunk of the peak as it erupted. This was followed by plumes of hot gas and ash riding down the volcano’s summit and spreading out in a 5-kilometer (3 mile) diameter. Ash falls were widespread, covering entire villages in the area and leading to airline pilots being issued the highest of alerts for the region.
In fact, ash falls were recorded as far as away as the town of Lhokseumawe – located some 260 km (160 mi) to the north. To address the threat to public health, the Indonesian government advised people to stay indoors due to poor air quality, and officials were dispatched to Sumatra to hand out face masks. Due to its composition and its particulate nature, volcanic ash is a severe health hazard.
On the one hand, it contains sulfur dioxide (SO²), which can irritate the human nose and throat when inhaled. The gas also reacts with water vapor in the atmosphere to produce acid rain, causing damage to vegetation and drinking water. It can also react with other gases in the atmosphere to form aerosol particles that can create thick hazes and even lead to global cooling.
These levels were recorded by the Suomi-NPP satellite using its Ozone Mapper Profiler Suite (OMPS). The image below shows what SO² concentrations were like at 1:20 p.m. local time (06:20 Universal Time) on February 19th, several hours after the eruption. The maximum concentrations of SO² reached 140 Dobson Units in the immediate vicinity of the mountain.
Erik Klemetti, a volcanologist, was on hand to witness the event. As he explained in an article for Discovery Magazine:
“On February 19, 2018, the volcano decided to change its tune and unleashed a massive explosion that potentially reached at least 23,000 and possibly to up 55,000 feet (~16.5 kilometers), making it the largest eruption since the volcano became active again in 2013.”
Klemetti also cited a report that was recently filed by the Darwin Volcanic Ash Advisory Center – part of the Australian Government’s Bureau of Meteorology. According to this report, the ash will drift to the west and fall into the Indian Ocean, rather than continuing to rain down on Sumatra. Other sensors on NASA satellites have also been monitoring Mount Sinabung since its erupted.
In addition, data from the Aura satellite‘s Ozone Monitoring Instrument (OMI) recently indicated rising levels of SO² around Sinabung, which could mean that fresh magma is approaching the surface. As Erik Klemetti concluded:
“This could just be a one-off blast from the volcano and it will return to its previous level of activity, but it is startling to say the least. Sinabung is still a massive humanitarian crisis, with tens of thousands of people unable to return to their homes for years. Some towns have even been rebuilt further from the volcano as it has shown no signs of ending this eruptive period.”
Be sure to check out this video of the eruption, courtesy of New Zealand Volcanologist Dr. Janine Krippner:
It’s easy to imagine the excitement NASA personnel must have felt when an amateur astronomer contacted NASA to tell them that he might have found their missing IMAGE satellite. After all, the satellite had been missing for 10 years.
IMAGE, which stands for Imager for Magnetopause-to-Aurora Global Exploration, was launched on March 25th, 2000. In Dec. 2005 the satellite failed to make routine contact, and in 2007 it failed to reboot. After that, the mission was declared over.
It’s astonishing that after 10 years, the satellite has been found. It’s even more astonishing that it was an amateur who found it. As if the story couldn’t get any more interesting, the amateur astronomer who found it—Scott Tilly of British Columbia, Canada—was actually looking for a different missing satellite: the secret ZUMA spy satellite launched by the US government on January 7, 2018. (If you’re prone to wearing a tin foil hat, now might be a good time to reach for one.)
After Tilly contacted NASA, they hurried to confirm that it was indeed IMAGE that had been found. To do that, NASA employed 5 separate antennae to seek out any radio signals from the satellite. As of Monday, Jan. 29, signals received from all five sites were consistent with the radio frequency characteristics expected of IMAGE.
In a press release, NASA said, “Specifically, the radio frequency showed a spike at the expected center frequency, as well as side bands where they should be for IMAGE. Oscillation of the signal was also consistent with the last known spin rate for IMAGE.”
“…the radio frequency showed a spike at the expected center frequency…” – NASA Press Release confirming the discovery of IMAGE
Then, on January 30, the Johns Hopkins Applied Physics Lab (JHUAPL) reported that they had successfully collected telemetry data from the satellite. In that signal was the ID code 166, the code for IMAGE. There were probably some pretty happy people at NASA.
So, now what?
NASA’s next step is to confirm without a doubt that this is indeed IMAGE. That means capturing and analyzing the data in the signal. That will be a technical challenge, because the types of hardware and operating systems used in the IMAGE Mission Operations Center no longer exist. According to NASA, “other systems have been updated several versions beyond what they were at the time, requiring significant reverse-engineering.” But that should be no problem for NASA. After all, they got Apollo 13 home safely, didn’t they?
If NASA is successful at decoding the data in the signal, the next step is to attempt to turn on IMAGE’s science payload. NASA has yet to decide how to proceed if they’re successful.
IMAGE was the first spacecraft designed to “see the invisible,” as they put it back then. Prior to IMAGE, spacecraft examined Earth’s magnetosphere by detecting particles and fields they encountered as they passed through them. But this method had limited success. The magnetosphere is enormous, and simply sampling a small path—while better than nothing—did not give us an accurate understanding of it.
IMAGE was going to do things differently. It used 3-dimensional imaging techniques to measure simultaneously the densities, energies and masses of charged particles throughout the inner magnetosphere. To do this, IMAGE carried a payload of 7 instruments:
High Energy Neutral Atom (HENA) imager
Medium Energy Neutral Atom (MENA) imager
Low Energy Neutral Atom (LENA) imager
Extreme Ultraviolet (EUV) imager
Far Ultraviolet (FUV) imager
Radio Plasma Imager (RPI)
Central Instrument Data Processor (CIDP)
These instruments allowed IMAGE to not only do great science, and to capture great images, but also to create some stunning never-seen-before movies of auroral activity.
This is a fascinating story, and it’ll be interesting to see if NASA can establish meaningful contact with IMAGE. Will it have a treasure trove of unexplored data on-board? Can it be re-booted and brought back into service? We’ll have to wait and see.
This story is also interesting culturally. IMAGE was in service at a time when the internet wasn’t as refined as it is currently. NASA has mastered the internet and public communications now, but back then? Not so much. For example, to build up interest around the mission, NASA gave IMAGE its own theme song, titled “To See The Invisible.” Yes, seriously.
But that’s just a side-note. IMAGE was all about great science, and it accomplished a lot. You can read all about IMAGE’s science achievements here.
For several months, scientists have been keeping an eye on a piece of Antarctica’s Larsen C ice shelf, waiting for the inevitable. And now it has happened.
Sometime between July 10 and July 12, 2017 a trillion ton iceberg split off, “changing the outline of the Antarctic Peninsula forever,” said one scientist.
The new iceberg is now called A68, and at 2,240 square miles (5,800 square km) it is one of the biggest ever recorded, about the size of Delaware in the US, or twice the size of Luxembourg.
A fissure on the ice shelf first appeared several years ago, but seemed relatively stable until January 2016, when it began to lengthen. In January 2017 alone, the crack grew by 20 km, reaching a total length of about 175 km.
The calving of the iceberg was confirmed by the Visible Infrared Imaging Radiometer Suite (VIIRS) on the Suomi NPP satellite and was reported this morning by Project MIDAS, an Antarctic research project based in the UK.
The MODIS instrument on NASA’s Aqua satellite also confirmed the complete separation of the iceberg.
Larsen C is a floating platform of glacial ice on the east side of the Antarctic Peninsula, is the fourth largest ice shelf ringing Earth’s southernmost continent. With the break-off of this iceberg, the Larsen C shelf area has shrunk by approximately 10 percent.
Some scientists say the Larsen C rift and iceberg calving is not a warning of imminent sea level rise, and linking climate change to this specific event is complicated. Adrian Luckman, Professor of Glaciology and Remote Sensing from Swansea University wrote a detailed explanation of this for The Conversation.
David Vaughan, glaciologist and Director of Science at British Antarctic Survey (BAS), said, “Larsen C itself might be a result of climate change, but, in other ice shelves we see cracks forming, which we don’t believe have any connection to climate change. For instance on the Brunt Ice Shelf where BAS has its Halley Station, there those cracks are a very different kind which we don’t believe have any connection to climate change.”
While Vaughan said they see no obvious signal that climate warming is causing the whole of Antarctica to break up, he added that there is little doubt that climate change is causing ice shelves to disappear in some parts of Antarctica at the moment.
“Around the Antarctic Peninsula, where we saw several decades of warming through the latter half of the 20th century, we have seen these ice shelves collapsing and ice loss increasing,” he said. “There are other parts of the Antarctica that which are losing ice to the oceans but those are affected less by atmospheric warming and more by ocean change.
Scientists said the loss of such a large piece is of interest because ice shelves along the peninsula play an important role in ‘buttressing’ glaciers that feed ice seaward, effectively slowing their flow.
“The interesting thing is what happens next, how the remaining ice shelf responds,” said Kelly Brunt, a glaciologist with NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and the University of Maryland in College Park. “Will the ice shelf weaken? Or possibly collapse, like its neighbors Larsen A and B? Will the glaciers behind the ice shelf accelerate and have a direct contribution to sea level rise? Or is this just a normal calving event?”
The U.S. National Ice Center will monitor the trajectory of the new iceberg, but they don’t expect it to travel far very fast, and it shouldn’t cause any immediate problems for navigation of ships.
Back in 1993, Carl Sagan encountered a puzzle. The Galileo spacecraft spotted flashes coming from Earth, and nobody could figure out what they were. They called them ‘specular reflections’ and they appeared over ocean areas but not over land.
The images were taken by the Galileo space probe during one of its gravitational-assist flybys of Earth. Galileo was on its way to Jupiter, and its cameras were turned back to look at Earth from a distance of about 2 million km. This was all part of an experiment aimed at finding life on other worlds. What would a living world look like from a distance? Why not use Earth as an example?
Fast-forward to 2015, when the National Oceanographic and Atmospheric Administration (NOAA) launched the Deep Space Climate Observatory (DSCOVER) spacecraft. DSCOVER’s job is to orbit Earth a million miles away and to warn us of dangerous space weather. NASA has a powerful instrument on DSCOVER called the Earth Polychromatic Imaging Camera (EPIC.)
Every hour, EPIC takes images of the sunlit side of Earth, and these images can be viewed on the EPIC website. (Check it out, it’s super cool.) People began to notice the same flashes Sagan saw, hundreds of them in one year. Scientists in charge of EPIC started noticing them, too.
One of the scientists is Alexander Marshak, DSCOVR deputy project scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. At first, he noticed them only over ocean areas, the same as Sagan did 25 years ago. Only after Marshak began investigating them did he realize that Sagan had seen them too.
Back in 1993, Sagan and his colleagues wrote a paper discussing the results from Galileo’s examination of Earth. This is what they said about the reflections they noticed: “Large expanses of blue ocean and apparent coastlines are present, and close examination of the images shows a region of [mirror-like] reflection in ocean but not on land.”
Marshak surmised that there could be a simple explanation for the flashes. Sunlight hits a smooth part of an ocean or lake, and reflects directly back to the sensor, like taking a flash-picture in a mirror. Was it really that much of a mystery?
When Marshak and his colleagues took another look at the Galileo images showing the flashes, they found something that Sagan missed back in 1993: The flashes appeared over land masses as well. And when they looked at the EPIC images, they found flashes over land masses. So a simple explanation like light reflecting off the oceans was no longer in play.
“We found quite a few very bright flashes over land as well.” – Alexander Marshak, DSCOVR Deputy Project Scientist
“We found quite a few very bright flashes over land as well,” he said. “When I first saw it I thought maybe there was some water there, or a lake the sun reflects off of. But the glint is pretty big, so it wasn’t that.”
But something was causing the flashes, something reflective. Marshak and his colleagues, Tamas Varnai of the University of Maryland, Baltimore County, and Alexander Kostinski of Michigan Technological University, thought of other ways that water could cause the flashes.
The primary candidate was ice particles high in Earth’s atmosphere. High-altitude cirrus clouds contain tiny ice platelets that are horizontally aligned almost perfectly. The trio of scientists did some experiments to find the cause of the flashes, and published their results in a new paper published in Geophysical Research Letters.
“Lightning doesn’t care about the sun and EPIC’s location.” – Alexander Marshak, DSCOVR Deputy Project Scientist
As their study details, they first catalogued all of the reflective glints that EPIC found over land; 866 of them in a 14 month period from June 2015 to August 2016. If these flashes were caused by reflection, then they would only appear on locations on the globe where the angle between the Sun and Earth matched the angle between the DSCOVER spacecraft and Earth. As the catalogued the 866 glints, they found that the angle did match.
This ruled out something like lightning as the cause of the flashes. But as they continued their work plotting the angles, they came to another conclusion: the flashes were sunlight reflecting off of horizontal ice crystals in the atmosphere. Other instruments on DSCOVR confirmed that the reflections were coming from high in the atmosphere, rather than from somewhere on the surface.
“The source of the flashes is definitely not on the ground. It’s definitely ice, and most likely solar reflection off of horizontally oriented particles.” -Alexander Marshak, DSCOVR Deputy Project Scientist
Mystery solved. But as is often the case with science, answering one question leads to a couple other questions. Could detecting these glints be used in the study of exoplanets somehow? But that’s one for the space science community to answer.
As for Marshak, he’s an Earth scientist. He’s investigating how common these horizontal ice particles are, and what effect they have on sunlight. If that impact is measurable, then it could be included in climate modelling to try to understand how Earth retains and sheds heat.
NASA strives to explore space and to expand our understanding of our Solar System and beyond. But they also turn their keen eyes on Earth in an effort to understand how our planet is doing. Now, they’re releasing a new composite image of Earth at night, the first one since 2012.
We’ve grown accustomed to seeing these types of images in our social media feeds, especially night-time views of Earth from the International Space Station. But this new image is much more than that. It’s part of a whole project that will allow scientists—and the rest of us—to study Earth at night in unprecedented detail.
Night-time views of Earth have been around for 25 years or so, usually produced several years apart. Comparing those images shows clearly how humans are changing the face of the planet. Scientists have been refining the imaging over the years, producing better and more detailed images.
The team behind this is led by Miguel Román of NASA’s Goddard Space Flight Center. They’ve been analyzing data and working on new software and algorithms to improve the quality, clarity, and availability of the images.
VIIRS detects photons of light in 22 different wavelengths. It’s the first satellite instrument to make quantitative measurements of light emissions and reflections, which allows researchers to distinguish the intensity, types and the sources of night lights over several years.
Producing these types of maps is challenging. The raw data from SUOMI NPP and its VIIRS instrument has to be skillfully manipulated to get these images. The main challenge is the Moon itself.
As the Moon goes through its different phases, the amount of light hitting Earth is constantly changing. Those changes are predictable, but they still have to be accounted for. Other factors have to be managed as well, like seasonal vegetation, clouds, aerosols, and snow and ice cover. Other changes in the atmosphere, though faint, also affect the outcome. Phenomenon like auroras change the way that light is observed in different parts of the world.
The newly released maps were made from data throughout the year, and the team developed algorithms and code that picked the clearest night views each month, ultimately combining moonlight-free and moonlight-corrected data.
The SUOMI NPP satellite is in a polar orbit, and it observes the planet in vertical swaths that are about 3,000 km wide. With its VIIRS instrument, it images almost every location on the surface of the Earth, every day. VIIRS low-light sensor has six times better spatial resolution for distinguishing night lights, and 250 times better resolution overall than previous satellites.
What do all those numbers mean? The team hopes that their new techniques, combined with the power of VIIRS, will create images with extraordinary resolution: the ability to distinguish a single highway lamp, or fishing boat, anywhere on the surface of Earth.
Beyond thought-provoking eye-candy for the rest of us, these images of night-time Earth have practical benefits to researchers and planners.
“Thanks to VIIRS, we can now monitor short-term changes caused by disturbances in power delivery, such as conflict, storms, earthquakes and brownouts,” said Román. “We can monitor cyclical changes driven by reoccurring human activities such as holiday lighting and seasonal migrations. We can also monitor gradual changes driven by urbanization, out-migration, economic changes, and electrification. The fact that we can track all these different aspects at the heart of what defines a city is simply mind-boggling.”
These maps of night-time Earth are a powerful tool. But the newest development will be a game-changer: Román and his team aim to provide daily, high-definition views of Earth at night. Daily updates will allow real-time tracking of changes on Earth’s surface in a way never before possible.
Maybe the best thing about these upcoming daily night-time light maps is that they will be publicly available. The SUOMI NPP satellite is not military and its data is not classified in any way. They hope to have these daily images available later this year. Once the new daily light-maps of Earth are available, it’ll be another powerful tool in the hands of researchers and planners, and the rest of us.
These maps will join other endeavours like NASA-EOSDIS Worldview. Worldview is a fascinating, easy-to-use data tool that anyone can access. It allows users to look at satellite images of the Earth with user-selected layers for things like dust, smoke, draught, fires, and storms. It’s a powerful tool that can change how you understand the world.
Mount Etna is Europe’s most active volcano, and it’s been spouting off since late February 2017. It spewed lava and gas with a rather big eruption last week, where 10 people were actually injured. The Expedition 50 crew on board the International Space Station have been able to capture both day and nighttime views of the activity from orbit.
ESA astronaut Thomas Pesquet took the image below on March 19, and shared it on Twitter, writing, “Mount Etna, in Sicily. The volcano is currently erupting and the molten lava is visible from space, at night! (the red lines on the left).”
This crop shows the glowing lava:
Mount Etna towers above the city of Catania on the island of Sicily. Scientists estimate it has been active for about 500,000 years. The first recorded eruption dates back to 1500 B.C., and it has erupted over 200 times since then.
NASA’s Suomi NPP satellite also spotted nighttime activity from orbit. The image was acquired by the Visible Infrared Imaging Radiometer Suite (VIIRS), using its “day-night band,” which detects light in a range of wavelengths and uses filtering techniques to observe signals such as gas flares, city lights, and reflected moonlight. In this image, it detected the nighttime glow of molten lava.