Picking Up Penguins From Space

Danger Islands, off Antarctica. Landsat-8 image acquired on 7th December 2017. Image courtesy of NASA/USGS.

World Wildlife Day is the 3rd March, and so fittingly this blog is looking at how satellite imagery and remote sensing techniques were used to recently discover an unknown colony of 1.5 million Adélie penguins on the Danger Islands off the Antarctica Peninsula in the north-western Weddell Sea. Adélie penguins only live along the Antarctic coast, and they grow to a height of around 70cm and weigh between three and six kilograms.

The paper by ‘Multi-modal survey of Adélie penguin mega-colonies reveals the Danger Islands as a seabird hotspot by Borowicz et al was published in Scientific Reports on the 2nd March 2018. It is interestingly not only because of the discovery of unknown penguins but also because the research combines historic aerial imagery, satellite imagery, drone footage and remote sensing techniques.

The research has its roots in an earlier paper by Lynch and Schwaller from 2014, entitled ‘Mapping the Abundance and Distribution of Adélie Penguins Using Landsat-7: First Steps towards an Integrated Multi-Sensor Pipeline for Tracking Populations at the Continental Scale.’ It describes the development of an algorithm to analyse Landsat and high resolution imagery from WorldView-2 to estimate the size of penguin colonies based on the extent of the guana area. A classification approach was developed from a training dataset of 473 Landsat-7 pixels covering existing Adeline colonies, supported by over 10,000 pixels relating to features such as rock, soil and vegetation.

In the recently published paper, of which Heather Lynch was also a co-author, the team combined a range of imagery alongside some in-situ data to achieve their results. Different types of imagery were used:

  • High Resolution Imagery: Areas of guano staining on the Danger Islands were identified manually from WorldView-2 scenes.
  • Historical aerial photographs: Images taken by Falkland Islands Dependencies Aerial Survey Expedition (FIDASE) on the 31st January 1957 were digitally scanned and geo-referenced to the WorldView-2 data. They were then divided into polygons and analysed using manual classification processing using the open source QGIS software.
  • Landsat: The algorithm previously developed by Lynch and Schwaller was enhanced to work with data from Landsat-4, 7 and 8 by calculating the mean difference of similar bands from Landsat-4 and 8 compared to Landsat-7, and then adjusting based on the mean differences in each spectral band. The enhanced algorithm was then used to classify the penguin colony areas.
  • Drone data: Using a 1.2 megapixel camera flown at height of between 25 m and 45 m, captured footage was processed to produce georeferenced orthomosaics of the Danger Islands. Machine learning techniques were then applied using a deep neural network to locate and identify potential penguins. A training dataset of 160 images with 1237 penguins, followed by a validation dataset of 93 images with 673 penguins was used to teach the network. Once fully trained it analysed all the islands, and the results were validated with a number of manual counts. The scientists worked on an accuracy of plus or minus ten percent for the automated counts, although the variation with the in-situ counts was only 0.6 percent.

The outcome of this research was an identification of 751,527 pairs of previously unknown Adélie penguins on the Danger Islands. More surprisingly is that this increases the world estimates of this type of penguin by almost 50%, when it had been thought that the population had been declining for the last 40 years. The historical aerial imagery has led scientists to speculate that this new colony has remained constant for around the last 60 years in contrast to other known colonies.

This work is a great example of not only how much can be achieved with free-to-access imagery, but also how satellite imagery is helping us discover new things about our planet.

Monitoring Water Quality from Space

Algal Blooms in Lake Erie, around Monroe, acquired by Sentinel-2 on 3rd August 2017. Data Courtesy of ESA/Copernicus.

Two projects using Earth Observation (EO) data to monitor water quality caught our eye recently. As we’re in process of developing two water quality products for our own online portal, we’re interested in what everyone else is doing!

At the end of January UNESCO’s International Hydrological Programme launched a tool to monitor global water quality. The International Initiative on Water Quality (IIWQ) World Water Quality Portal, built by EOMAP, provides:

  • turbidity and sedimentation distribution
  • chlorophyll-a concentration
  • Harmful Algal Blooms indicator
  • organic absorption
  • surface temperature

Based on optical data from Landsat and Sentinel-2 it can provide global surface water mosaics at 90 m spatial resolution, alongside 30 m resolution for seven pilot river basins.  The portal was launched in Paris at the “Water Quality Monitoring using Earth Observation and Satellite-based Information” meeting and was accompanied by an exhibition on “Water Quality from the Space – Mesmerizing Images of Earth Observation”.

The tool, which can be found here, focuses on providing colour visualizations of the data alongside data legends to help make it as easy as possible to use. It is hoped that this will help inform and educate policy makers, water professionals and the wider public about the value of using satellite data from monitoring water resources.

A second interesting project, albeit on a smaller scale, was announced last week which is going to use Sentinel-2 imagery to monitor water quality in Scottish Lochs. Dr Claire Neil, from the University of Stirling, is leading the project and will be working with Scottish Environment Protection Agency. It will use reflectance measures to estimate the chlorophyll-a concentrations to help identify algal blooms and other contaminants in the waters. The project will offer an alternative approach to the current water quality monitoring, which uses sampling close to the water’s edge.

An interesting feature of the project, particularly for us, is the intention to focus on developing this work into an operational capability for SEPA to enable them to improve their approach to assessing water quality.

This transition from a ‘good idea’ into an operational product that will be used, and therefore purchased, by end users is what all EO companies are looking for and we’re not different. Our Pixalytics Portal which we discussed a couple of weeks ago is one of the ways we are trying to move in that direction. We have two water quality monitoring products on it:

  • Open Ocean Water Quality product extracts time-series data from a variety of 4 km resolution satellite datasets from NASA, giving an overview what is happening in the water without the need to download a lot of data.
  • Planning for Coastal Airborne Lidar Surveys product provides an assessment of the penetration depth of a Lidar laser beam, from an airborne survey system, within coastal waters based on the turbidity of the water. This ensures that companies who plan overflights can have confidence in how far their Lidar will see.

We’re just at the starting point in productizing the services we offer, and so it is always good to see how others are approaching the similar problem!

Celebrating Landsat & the Winter Olympics

First Landsat image acquired in 2013 showing area around Fort Collins, Colorado. Data courtesy of NASA/USGS.

The Landsat programme achieved a couple of significant milestones over the last two weeks. Firstly, the 11th February marked the five year anniversary of the launch of Landsat 8 which took place at the Vandenberg Air Force Base, California, in 2013. The image to the right is the first one acquired by Landsat 8 and shows the area around Fort Collins, Colorado with the Horsetooth Reservoir very clear left of centre.

This anniversary is an interesting one because Landsat 8 was only designed for an operational life of five years. Obviously it has already exceeded this and these planned lifespans are very conservative. More often the amount of fuel on board is a more relevant assessment for lifespan and for Landsat 8 the initial assessment was a 10 year lifespan. However, even this tends to be a conservative estimate. As an example, nineteen years ago Landsat 7 was launched with similar planned operational lifespans. It is still working today, although there have been some degradation issues, and IT achieved its own significant milestone on the 1st February when it completed its 100,000th orbit of the Earth.

Landsat 8 is in a sun-synchronous orbit at an altitude of 705 km, circles the Earth every 98.9 minutes and in the last five years has undertaken over 26,500 orbits according to NASA who have produced a short celebratory video.

It has two main instruments, an Operational Land Imager (OLI) and the Thermal Infrared Sensor (TIRS), which together measure eleven different spectral bands. The TIRS has two thermal bands which are used for sensing temperature, whereas the OLI measures nine spectral bands:

  • Three visible light bands that approximate red, green and blue
  • One near infrared band
  • Two shortwave infrared bands
  • Panchromatic band with a higher spatial resolution
  • The two final bands focus on coastal aerosols and cirrus clouds.

With the exception of the highest polar latitudes, Landsat 8 acquires images of the whole Earth every 16 days which has meant it has acquired over 1.1 million images of the Earth that accounts for 16 percent of all the data in the Landsat multi-mission archive.

Landsat 8 image of Pyeongchang, South Korea, which is hosting the 2018 Winter Olympics. Data acquired 11th February 2018. Data courtesy of NASA/USGS.

The image to the left is the Pyeongchang region of South Korea where the Winter Olympics are currently taking place acquired by Landsat on its five year anniversary on the 11th February. Pyeongchang is in the north west of South Korea in the TaeBaek Mountains just over one hundred miles from the capital, Seoul. The left area of the image shows the mountain range where the skiing, biathlon, ski jumping, bobsled, luge and skeleton events take place and to the right is the coastal city of Gangneung, where the ice hockey, curling, speed skating and figure skating are taking place.

With its forty-five year archive, Landsat offers the longest continuous dataset of Earth observations and is critical to researchers and scientists. Landsat 9 is planned to be launched in 2020 and Landsat 10 is already being discussed.

Congratulations to Landsat 7 and 8, and we look forward to many more milestones in the future.

Five Learning Points For Developing An Earth Observation Product Portal

Landsat mosaic image of the Isle of Wight. Data courtesy of NASA.

This week we’re gently unveiling our Pixalytics Portal at the DATA.SPACE 2018 Conference taking place in Glasgow.

We’ve not attended DATA.SPACE before, but great feedback from some of the last years attendees convinced us to come. It’s an international conference focusing on the commercial opportunities available through the exploitation of space-enabled data and so it seemed the perfect place to demonstrate our new development.

Regular readers will know we’ve had the product portal idea for a little while, but it often went to the back of the work queue when compared to existing work, bid preparation and our other developments. Hence, six months ago we pinpointed the DATA.SPACE as our unveiling event!

On the 1st and 2nd February at Technology & Innovation Centre in Glasgow we have a stand where we’re inviting everyone to come up and have a look at the portal and give us feedback on the idea, principles and the look and feel of the portal.

We’re demonstrating five products, and we’re looking to expand this, these are:

  • Landscape Maps of the UK
  • Water Extent Mapping
  • Flood Water Mapping
  • Coastal Airborne Lidar Survey Planning Datasets
  • Open Ocean Water Quality Parameters

We’re not just attending, we’re exhibiting and Sam’s presenting!! So we’re going to have the full triumvirate conference experience. Sam is presenting in the first day’s second session titled ‘Looking at our Earth’ which starts at 11.10am. Her presentation is called ‘Growing Earth Observation By Being More Friendly.’

Developing this portal to its current state has been a really interesting journey. When we began we didn’t know why some of the larger companies haven’t cracked this already! Six months later and we’ve started to understand the challenges!

We thought it might be helpful to reveal are five top learning points for any other SME’s in our industry considering developing a portal. They are:

  1. Challenging the Digital e-commerce Process: Standard digital e-commerce systems allow customers to purchase a product and then download it immediately. The need to have an additional step of a few minutes, or even hours, to undertake data processing complicates things. It means that simple off-the-shelf plug-ins won’t work.
  2. Don’t Go for Perfection: Building a perfect portal will take time. We’ve adopted the approach of Eric Ries, author of The Startup Way, who advocates building a system for ten purchases. We’re perhaps a bit beyond that, but certainly we know that this will only be the first iteration of our portal.
  3. Linking The Moving Parts: Our portal has a web-front end, a cloud processing backend and the need to download requested data. We’ve tried to limit the amount of data and processing needed, but we can’t eliminate it entirely. This means there are a lot of moving parts to get right, and a lot of error capturing to be done!
  4. Legal & Tax issues: Sorting out the products is only one part of the process, don’t forget to do the legal and tax side as that has implications on your approach. We have learnt a lot about the specific requirements of digital services in e-commerce!
  5. Have a deadline: We chose to exhibit at DATA.SPACE to give us a deadline. We knew if we didn’t have a hard deadline we’d still be debating the products to include, and have developed none of them! The deadline has moved us really close to having a portal.

If you’re at DATA.SPACE this week, please come up and say hello. If you’ve got a few minutes to spare we’d love to get you feedback on our portal.

Have you read the top Pixalytics blogs of 2017?

World Cloud showing top 100 words from Pixalytics 2017 blogs

In our final blog of the year, we’re looking back at our most popular posts of the last twelve months. Have you read them all?

Of the top ten most read blogs, nine were actually written in previous years. These were:

You’ll notice that this list is dominated by our annual reviews of the number of satellites, and Earth observation satellites, orbiting the Earth. It often surprises us to see where these blogs are quoted and we’ve been included in articles on websites for Time Magazine, Fortune Magazine and the New Statesman to name a few!

So despite only being published in November this year coming in as the fourth most popular blog of the year was, unsurprisingly:

For posts published in 2017, the other nine most popular were:

2017 has been a really successful one for our website. The number of the views for the year is up by 75%, whilst the number of unique visitors has increased by 92%!

Whilst hard work, we do enjoy writing our weekly blog – although staring at a blank screen on a Wednesday morning without any idea of what we’ll publish a few hours later can be daunting!

We’re always delighted at meetings and conferences when people come up and say they read the blog. It’s nice to know that we’re read both within our community, as well as making a small contribution to informing and educating people outside the industry.

Thanks for reading this year, and we hope we can catch your eye again next year.

We’d like to wish everyone a Happy New Year, and a very successful 2018!

Big Data From Space

Last week I attended the 2017 Conference on Big Data from Space (BiDS’17) that was held in Toulouse, France. The conference was co-organised by the European Space Agency (ESA), the Joint Research Centre (JRC) of the European Commission (EC), and the European Union Satellite Centre (SatCen). It aimed to bring together people from multiple disciplines to stimulate the exploitation Earth Observation (EO) data collected in space.

The event started on Tuesday morning with keynotes from the various co-organising space organisations. Personally, I found the talk by Andreas Veispak, from the European Commission’s (EC) DG GROW department which is responsible for EU policy on the internal market, industry, entrepreneurship and SMEs, particularly interesting. Andreas has a key involvement in the Copernicus and Galileo programmes and described the Copernicus missions as the first building block for creating an ecosystem, which has positioned Europe as a global EO power through its “full, free and open” data policy.

The current Sentinel satellite missions will provide data continuity until at least 2035 with huge amounts of data generated, e.g., when all the Sentinel satellite missions are operational over 10 petabytes of data per year will be produced. Sentinel data has already been a huge success with current users exceeding what was expected by a factor of 10 or 20 and every product has been downloaded at least 10 times. Now, the key challenge is to support these users by providing useful information alongside the data.

The ESA presentation by Nicolaus Hanowski continued the user focus by highlighting that there are currently over 100 000 registered Copernicus data hub users. Nicolaus went on to describe that within ESA success is now being measured by use of the data for societal needs, e.g., the sustainable development goals, rather than just the production of scientific data. Therefore, one of the current aims is reduce the need for downloading by having a mutualised underpinning structure, i.e. the Copernicus Data and Information Access Services (DIAS) that will become operational in the second quarter of 2018, which will allow users to run their computer code on the data without the need for downloading. The hope is that this will allow users to focus on what they can do with the data, rather than worrying around storing it!

Charles Macmillan from JRC described their EO Data and Processing Platform (JEODPP) which is a front end based around the Jupyter Notebook that allows users to ask questions using visualisations and narrative text, instead of just though direct programming. He also noted that increasingly the data needed for policy and decision making is held by private organisations rather than government bodies.

The Tuesday afternoon was busy as I chaired the session on Information Generation at Scale. We had around 100 people who heard some great talks on varied subjects such as mass processing of Sentinel & Landsat data for mapping human settlements, 35 years of AVHRR data and large scale flood frequency maps using SAR data.

‘Application Of Earth Observation To A Ugandan Drought And Flood Mitigation Service’ poster

I presented a poster at the Wednesday evening session, titled “Application Of Earth Observation To A Ugandan Drought And Flood Mitigation Service”. We’re part of a consortium working on this project which is funded via the UK Space Agency’s International Partnership Programme. It’s focus is on providing underpinning infrastructure for the Ugandan government so that end users, such as farmers, can benefit from more timely and accurate information – delivered through a combination of EO, modelling and ground-based measurements.

It was interesting to hear Grega Milcinski from Sinergise discuss a similar approach to users from the lessons they learnt from building the Sentinel Hub. They separated the needs of science, business and end users. They’ve chosen not to target end users due to the challenges surrounding the localisation and customisation requirements of developing apps for end users around the world. Instead they’ve focussed on meeting the processing needs of scientific and business users to give them a solid foundation upon which they can then build end user applications. It was quite thought provoking to hear this, as we’re hoping to move towards targeting these end users in the near future!

There were some key technology themes that came of the presentations at the conference:

  • Jupyter notebooks were popular for frontend visualisation and data analytics, so users just need to know some basic python to handle large and complex datasets.
  • Making use of cloud computing using tools such as Docker and Apache Spark for running multiple instances of code with integrated parallel processing.
  • Raw data and processing on the fly: for both large datasets within browsers and by having the metadata stored so you can quickly query before committing to processing.
  • Analysis ready data in data cubes, i.e. the data has been processed to a level where remote sensing expertise isn’t so critical.

It was a great thought provoking conference. If you’d like to get more detail on what was presented then a book of extended abstracts is available here. The next event is planned for 19-21 February 2019 in Munich, Germany and I’d highly recommend it!

Inspiring the Next Generation of EO Scientists

Artist's rendition of a satellite - 3dsculptor/123RF Stock Photo

Artist’s rendition of a satellite – 3dsculptor/123RF Stock Photo

Last week, whilst Europe’s Earth Observation (EO) community was focussed on the successful launch of Sentinel-5P, over in America Tuesday 10th October was Earth Observation Day!

This annual event is co-ordinated by AmericaView, a non-profit organisation, whose aim to advance the widespread use of remote sensing data and technology through education and outreach, workforce development, applied research, and technology transfer to the public and private sectors.

Earth Observation Day is a Science, Technology, Engineering, and Mathematics (STEM) event celebrating the Landsat mission and its forty-five year archive of imagery. Using satellite imagery provides valuable experience for children in maths and sciences, together with introducing subjects such as land cover, food production, hydrology, habitats, local climate and spatial thinking. The AmericaView website contains a wealth of EO materials available for teachers to use, from fun puzzles and games through to a variety of remote sensing tutorials. Even more impressive is that the event links schools to local scientists in remote sensing and geospatial technologies. These scientists provide support to teachers including giving talks, helping design lessons or being available to answer student’s questions.

This is a fantastic event by AmericaView, supporting by wonderful resources and remote sensing specialists. We first wrote about this three years ago, and thought the UK would benefit from something similar. We still do. The UK Space Agency recently had an opportunity for organisations interested in providing education and outreach activities to support EO, satellite launch programme or the James Webb Space Telescope. It will be interesting to see what the successful candidates come up with.

At Pixalytics we’re passionate about educating and inspiring the next generation of EO scientists. For example, we regularly support the Remote Sensing and Photogrammetry Society’s Wavelength conference for students and early career scientists; and sponsored the Best Early-Career Researcher prize at this year’s GISRUK Conference. We’re also involved with two exciting events at Plymouth’s Marine Biological Association, a Young Marine Biologists (YMB) Summit for 12-18 year olds at the end of this month and their 2018 Postgraduate conference.

Why is this important?
The space industry, and the EO sector, is continuing to grow. According to Euroconsult’s ‘Satellites to Be Built & Launched by 2026 – I know this is another of the expensive reports we highlighted recently – there will be around 3,000 satellites with a mass above 50 kg launched in the next decade – of which around half are anticipated as being used for EO or communication purposes. This almost doubles the number of satellites launched in the last ten years and doesn’t include the increasing number of nano and cubesats going up.

Alongside the number of satellites, technological developments mean that the amount of EO data available is increasing almost exponentially. For example, earlier this month World View successfully completed multi-day flight of its Stratollite™ service, which uses high-altitude balloons coupled with the ability to steer within stratospheric winds. They can carry a variety of sensors, a mega-pixel camera was on the recent flight, offering an alternative vehicle for collecting EO data.

Therefore, we need a future EO workforce who are excited, and inspired, by the possibilities and who will take this data and do fantastic things with it.

To find that workforce we need to shout about our exciting industry and make sure everyone knows about the career opportunities available.

Can You See The Great Wall of China From Space?

Area north of Beijing, China, showing the Great Wall of China running through the centre. Image acquired by Sentinel-2 on 27th June 2017. Data courtesy of ESA/Copernicus.

Dating back over two thousand three hundred years, the Great Wall of China winds its way from east to west across the northern part of the country. The current remains were built during Ming Dynasty and have a length of 8 851.8 km according to 2009 work by the Chinese State Administration of Cultural Heritage and National Bureau of Surveying and Mapping Agency. However, if you take into account the different parts of the wall built by other dynasties, its length is almost twenty two thousand kilometres.

The average height of the wall is between six and seven metres, and its width is between four to five metres. This width would allow five horses, or ten men, to walk side by side. The sheer size of the structure has led people to believe that it could be seen from space. This was first described by William Stukeley in 1754, when he wrote in reference to Hadrian’s Wall that ‘This mighty wall of four score miles in length is only exceeded by the Chinese Wall, which makes a considerable figure upon the terrestrial globe, and may be discerned at the Moon.’

Despite Stukeley’s personal opinion not having any scientific basis, it has been repeated many times since. By the time humans began to go into space, it was considered a fact. Unfortunately, astronauts such as Buzz Aldrin, Chris Hatfield and even China’s first astronaut, Yang Liwei, have all confirmed that the Great Wall is not visible from space by the naked eye. Even Pixalytics has got a little involved in this debate. Two years ago we wrote a blog saying that we couldn’t see the wall on Landsat imagery as the spatial resolution was not small enough to be able to distinguish it from its surroundings.

Anyone who is familiar with the QI television series on the BBC will know that they occasionally ask the same question in different shows and give different answers when new information comes to light. This time it’s our turn!

Last week Sam was a speaker at the TEDx One Step Beyond event at the National Space Centre in Leicester – you’ll hear more of that in a week or two. However, in exploring some imagery for the event we looked for the Great Wall of China within Sentinel-2 imagery. And guess what? We found it! In the image at the top, the Great Wall can be seen cutting down the centre from the top left.

Screenshot of SNAP showing area north of Beijing, China. Data acquired by Sentinel-2 on 27th June 2017. Data courtesy of ESA/Copernicus.

It was difficult to spot. The first challenge was getting a cloud free image of northern China, and we only found one covering our area of interest north of Beijing! Despite Sentinel-2 having 10 m spatial resolution for its visible wavelengths, as noted above, the wall is generally narrower. This means it is difficult to see the actual wall itself, but it is possible to see its path on the image. This ability to see very small things from space by their influence on their surroundings is similar to how we are able to spot microscopic phytoplankton blooms. The image on the right is a screenshot from Sentinel Application Platform tool (SNAP) which shows the original Sentinel-2 image of China on the top left and the zoomed section identifying the wall.

So whilst the Great Wall of China might not be visible from space with the naked eye, it is visible from our artificial eyes in the skies, like Sentinel-2.

Algae Starting To Bloom

Algal Blooms in Lake Erie, around Monroe, acquired by Sentinel-2 on 3rd August 2017. Data Courtesy of ESA/Copernicus.

Algae have been making the headlines in the last few weeks, which is definitely a rarely used phrase!

Firstly, the Lake Erie freshwater algal bloom has begun in the western end of the lake near Toledo. This is something that is becoming an almost annual event and last year it interrupted the water supply for a few days for around 400,000 residents in the local area.

An algae bloom refers to a high concentration of micro algae, known as phytoplankton, in a body of water. Blooms can grow quickly in nutrient rich waters and potentially have toxic effects. Although a lot of algae is harmless, the toxic varieties can cause rashes, nausea or skin irritation if you were to swim in it, it can also contaminate drinking water and can enter the food chain through shellfish as they filter large quantities of water.

Lake Erie is fourth largest of the great lakes on the US/Canadian border by surface area, measuring around 25,700 square km, although it’s also the shallowest and at 484 cubic km has the smallest water volume. Due to its southern position it is the warmest of the great lakes, something which may be factor in creation of nutrient rich waters. The National Oceanic and Atmospheric Administration produce both an annual forecast and a twice weekly Harmful Algal Bloom Bulletin during the bloom season which lasts until late September. The forecast reflects the expected biomass of the bloom, but not its toxicity, and this year’s forecast was 7.5 on a scale to 10, the largest recent blooms in 2011 and 2015 both hit the top of the scale. Interestingly, this year NOAA will start incorporating Sentinel-3 data into the programme.

Western end of Lake Erie acquired by Sentinel-2 on 3rd August 2017. Data

Despite the phytoplankton within algae blooms being only 1,000th of a millimetre in size, the large numbers enable them to be seen from space. The image to the left is a Sentinel-2 image, acquired on the 3rd August, of the western side of the lake where you can see the green swirls of the algal bloom, although there are also interesting aircraft contrails visible in the image. The image at the start of the top of the blog is zoomed in to the city of Monroe and the Detroit River flow into the lake and the algal bloom is more prominent.

Landsat 8 acquired this image of the northwest coast of Norway on the 23rd July 2017,. Image courtesy of NASA/NASA Earth Observatory.

It’s not just Lake Erie where algal blooms have been spotted recently:

  • The Chautauqua Lake and Findley Lake, which are both just south of Lake Erie, have reported algal blooms this month.
  • NASA’s Landsat 8 satellite captured the image on the right, a bloom off the northwest coast of Norway on the 23rd July. It is noted that blooms at this latitude are in part due to the sunlight of long summer days.
  • The MODIS instrument onboard NASA’s Aqua satellite acquired the stunning image below of the Caspian Sea on the 3rd August.

Image of the Caspian Sea, acquired on 3rd August 2017, by MODIS on NASA’s Aqua satellite. Image Courtesy of NASA/NASA Earth Observatory.

Finally as reported by the BBC, an article in Nature this week proposes that it was a takeover by ocean algae 650 million years ago which essentially kick started life on Earth as we know it.

So remember, they may be small, but algae can pack a punch!

Landsat Turns 45!

False colour image of Dallas, Texas. The first fully operational Landsat image taken on July 25, 1972, Image courtesy: NASA’s Earth Observatory

Landsat has celebrated forty-five years of Earth observation this week. The first Landsat mission was Earth Resources Technology Satellite 1 (ERTS-1), which was launched into a sun-synchronous near polar orbit on the 23 July 1972. It wasn’t renamed Landsat-1 until 1975. It had an anticipated life of 1 year and carried two instruments: the Multi Spectral Scanner (MSS) and the Return-Beam Vidicon (RBV).

The Landsat missions have data continuity at their heart, which has given a forty-five year archive of Earth observation imagery. However, as technological capabilities have developed the instruments on consecutive missions have improved. To demonstrate and celebrate this, NASA has produced a great video showing the changing coastal wetlands in Atchafalaya Bay, Louisiana, through the eyes of the different Landsat missions.

In total there have been eight further Landsat missions, but Landsat 6 failed to reach its designated orbit and never collected any data. The missions have been:

  • Landsat 1 launched on 23 July 1972.
  • Landsat 2 launched on 22 January 1975.
  • Landsat 3 was launched on 5 March 1978.
  • Landsat 4 launched on 16 July 1982.
  • Landsat 5 launched on 1 March 1984.
  • Landsat 7 launched on 15 April 1999, and is still active.
  • Landsat 8 launched on 11 February 2013, and is still active.

Landsat 9 is planned to be launched at the end 2020 and Landsat 10 is already being discussed.

Some of the key successes of the Landsat mission include:

  • Over 7 million scenes of the Earth’s surface.
  • Over 22 million scenes had been downloaded through the USGS-EROS website since 2008, when the data was made free-to-access, with the rate continuing to increase (Campbell 2015).
  • Economic value of just one year of Landsat data far exceeds the multi-year total cost of building, launching, and managing Landsat satellites and sensors.
  • Landsat 5 officially set a new Guinness World Records title for the ‘Longest-operating Earth observation satellite’ with its 28 years and 10 months of operation when it was decommissioned in December 2012.
  • ESA provides Landsat data downlinked via their own data receiving stations; the ESA dataset includes data collected over the open ocean, whereas USGS does not, and the data is processed using ESA’s own processor.

The journey hasn’t always been smooth. Although established by NASA, Landsat was transferred to the private sector under the management of NOAA in the early 1980’s, before returning to US Government control in 1992. There have also been technical issues, the failure of Landsat 6 described above; and Landsat 7 suffering a Scan Line Corrector failure on the 31st May 2003 which means that instead of mapping in straight lines, a zigzag ground track is followed. This causes parts of the edge of the image not to be mapped, giving a black stripe effect within these images; although the centre of the images is unaffected the data overall can still be used.

Landsat was certainly a game changer in the remote sensing and Earth observation industries, both in terms of the data continuity approach and the decision to make the data free to access. It has provided an unrivalled archive of the changing planet which has been invaluable to scientists, researchers, book-writers and businesses like Pixalytics.

We salute Landsat and wish it many more years!