Sentinel To Be Launched

Sentinel-2 Image of Plymouth from 2016. Data courtesy of Copernicus/ESA.

Sentinel-2B was launched at 01:49 GMT on the 7th March from Europe’s Spaceport in French Guiana. It’s the second of a constellation of optical satellites which are part of the European Commission’s Copernicus Programme.

Its partner Sentinel-2A was launched on the 23rd June 2015, and has been providing some stunning imagery over the last eighteen months like the picture of Plymouth above. We’ve also used the data within our own work. Sentinel-2B carries an identical Multispectral Imager (MSI) instrument to its twin with 13 spectral bands:

  • 4 visible and near infrared spectral bands with a spatial resolution of 10 m
  • 6 short wave infrared spectral bands with a spatial resolution of 20 m
  • 3 atmospheric correction bands with a spatial resolution of 60 m

With a swath width of 290 km the constellation will acquire data in a band of latitude extending from 56° South around Isla Hornos, Cape Horn, South America to 83° North above Greenland, together with observations over specific calibration sites, such as Dome-C in Antarctica. Its focus will be on continental land surfaces, all European islands, islands bigger than 100 square kilometres, land locked seas and coastal waters.

The satellites will orbit 180 degrees apart at an altitude of 786 km, which means that together they will revisit the same point on Earth every five days at the equator, and it may be faster for parts of southern Europe. In comparison, Landsat takes sixteen days to revisit the same point.

With all Copernicus data being made freely available to anyone, the short revisit time offers opportunities small and micro Earth Observation businesses to establish monitoring products and services without the need for significant investment in satellite data paving the way for innovative new solutions to the way in which certain aspects of the environment are managed. Clearly, five day revisits are not ‘real-time’ and the spatial resolution of Sentinel data won’t be suitable for every problem.There is joint work between the US and Europe, to have complementarity with Landsat-8, which has thermal bands, and allows a further opportunity for cloud-free data acquisitions. Also, commercial operators provide higher spatial resolution data.

At Pixalytics we’re supporters of open source in both software and imagery. Our first point of call with any client is to ask whether the solution can be delivered through free to access imagery, as this can make a significant cost saving and allow large archives to be accessed. Of course, for a variety of reasons, it becomes necessary to purchase imagery to ensure the client gets the best solution for their needs. Of course, applications often include a combination of free to access and paid for data.

Next’s week launch offers new opportunities for downstream developers and we’ll be interested to see how we can exploit this new resource to develop our products and services.

Supporting Chimpanzee Conservation from Space

Gombe National Park, Tanzania. Acquired by Sentinel-2 in December 2016. Image courtesy of ESA.

Being able to visualise the changing face of the planet over time is one of the greatest strengths of satellite remote sensing. Our previous blog showed how Dubai’s coastline has evolved over a decade, and last week NASA described interesting work they’re doing on monitoring habitat loss for chimpanzees in conjunction with the Jane Goodall Institute.

Jane Goodall has spent over fifty years working to protect and conserve chimpanzees from the Gombe National Park in Tanzania, and formed the Jane Goodall Institute in 1977. The Institute works with local communities to provide sustainable conservation programmes.

A hundred years ago more than one million chimpanzees lived in Africa, today the World Wildlife Fund estimate the population may only be around 150,000 to 250,000. The decline is stark. For example, the Ivory Coast populations have declined by 90% within the last twenty years.

One of the key factors contributing to this decline is habitat loss, mostly through deforestation; although other factors such as hunting, disease and illegal capture also contributed.

Forests cover around 31% of the planet, and deforestation occurs when trees are removed and the land has another use instead of being a forest. In chimpanzee habitats, the deforestation is mostly due to logging, mining and drilling for oil. This change in land use can be monitored from space using remote sensing. Satellites produce regular images which can be used to monitor changes in the natural environment, in turn giving valuable information to conservation charities and other organisations.

In 2000 Lilian Pintea, from the Jane Goodall Institute, was shown Landsat images comparing the area around the Gombe National Park in 1972 and 1999. The latter image showed huge deforestation outside the park’s boundary. The Institute have continued to use Landsat imagery to monitor what is happening around the National Park. In 2009 they began a citizen science project with local communities giving them smartphones to report their observations. Combining these with ongoing satellite data from NASA has helped develop and implement local plans for land use and protection of the forests. Further visualisation of this work can be found here. The image at the top was acquired Sentinel-2 in December 2016 and shows the Gombe National Park, although it is under a little haze.

The satellite data supplied by NASA comes from the Landsat missions, which currently have an archive of almost forty-five years of satellite data, which is freely available to anyone. We also used Landsat for data in our Dubai animation last week. Landsat captures optical data, which means it operates in a similar manner to the human eye – although the instruments also have infrared capabilities. However, one drawback of optical instruments is that they cannot see through clouds. Therefore, whilst Landsat is great for monitoring land use when there are clear skies, it can be combined with synthetic aperture radar (SAR), from the microwave spectrum, as it can see through both clouds and smoke. This combination enables land use and land change to monitored anywhere in the world. Using the freely available Landsat and Sentinel-1 SAR data you could monitor what is happening to the forests in your neighbourhoods.

Satellite data is powerful tool for monitoring changes in the environment, and with the archive of data available offers a unique opportunity to see what has happened over the last four decades.

Islands of Sand

Animation showing the creation of islands in Dubai between 2001 & 2009 using Landsat images. Data courtesy of NASA.

This week we’re focusing on the development of Dubai’s land-coast interface between July 2001 and October 2009, looking specifically at the creation of the Palm islands and the World Archipelago. Dubai is the most populous city in the United Arab Emirates, home to 2.7 million people as of January 2017. In a place where Dubai police vehicles include a Lamborghini and a Ferrari, and where it’s possible to buy gold bars from vending machines perhaps it’s not surprising to see the creation of extravagant islands.

Palm Islands & The World Archipelago

In the animation at the top of the blog, the development of the Palm Islands and The World Archipelago are clearly visible. The first island created was Palm Jumeirah, the smallest of the three planned palm islands, and can be seen just off centre on the animation. It consists of a tree trunk, a crown with seventeen fronds and a surrounding crescent, and is approximately 25 square kilometres in size. Construction began in 2001 and was completed in 2006. The workers used GPS signals to determine the correct place to deposit sand to create the palm effect.

Built in tandem were the Palm Jebel Ali and The World Archipelago. Construction began in 2002 and was expected to be completed in 2015, however work stopped in 2008 due to the financial crisis. Work has remained suspended on Palm Jebel Ali, but development on the World may be about to start. The World has three hundred islands reclaimed from the sea, but most of them are bare sand. In the last twelve months there have been rumours that ‘The Heart of Europe’ project and floating seahorses around St Petersburg island could be developed in the near future.

It is also possible to see the preliminary creation of Palm Deira at the top of the animation. 300 million cubic metres of sand were used to form the initial reclamation. However, between 2009 and 2016 there has been no further development.

Images of Dubai in 2001, left, and 2009 taken by Landsat 7. Data courtesy of NASA.

It is also worth noting the significant urban sprawl between the first and last images. Dubai’s population increased by 95%, from 910,336 to 1,770,978, during the period we’re looking at and whilst the growth of Dubai is obvious, it is particularly visible southeast of the Palm Jumeirah development.

Creating the Time Series Animation

The animation was created using the first (blue) visible band of the Landsat 7 Enhanced Thematic Mapper Plus (ETM+) instrument. In May 2003, the scan line corrector – used to compensate for forward motion of the spacecraft, ensuring scan lines are parallel – failed. Consequently, the instrument images in a zigzag fashion; some data is captured twice, whilst some is not captured at all. As a result, 22 % of data in Landsat 7 images post May 2003 are missing. To compensate for this we’ve used a Geospatial Data Abstraction Library (GDAL) tool to fill “no data” regions by interpolating from nearby valid pixels. The results, whilst not perfect, are nearly indistinguishable at this resolution.

Impacts of the Islands

The development of these islands has not been without its criticism as it has impacted the local ecology. The dredging of sand has increased the turbidity of the seawater, with sediment transport evident in the animation, which has damaged coral reefs. In addition, water around parts of the islands can remain almost stationary for weeks, increasing the risk of algal blooms. Whilst fish have returned to these waters, they are not the same species as were there before.

Viewed from space, both the speed and scale of the development is mesmerising. It is no surprise that tourism is a vitally important part of the local economy, attracting more than 13 million visitors in 2014. With the limitations of available land in Dubai, developments are sure to start again.

 

Blog produced by Tom Jones on work placement with Pixalytics Ltd.

Earth Observation Looking Good in 2017!

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

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

2017 is looking like an exciting one for Earth Observation (EO), judging by the number of significant satellites planned for launch this year.

We thought it would be interesting to give an overview of some of the key EO launches we’ve got to look forward to in the next twelve months.

The European Space Agency (ESA) has planned launches of:

  • Sentinel-2B in March, Sentinel-5p in June and Sentinel-3B in August – all of which we discussed last week.
  • ADM-Aeolus satellite is intended to be launched by the end of the year carrying an Atmospheric Laser Doppler Instrument. This is essentially a lidar instrument which will provide global measurements of wind profiles from ground up to the stratosphere with 0.5 to 2 km vertical resolution.

From the US, both NASA and NOAA have important satellite launches:

  • NASA’s Ionospheric Connection Explorer (ICON) Mission is planned for June, and will provide observations of Earth’s ionosphere and thermosphere; exploring the boundary between Earth and space.
  • NASA’s ICESat-2 in November that will measure ice sheet elevation, ice sheet thickness changes and the Earth’s vegetation biomass.
  • In June NOAA will be launching the first of its Joint Polar Satellite System (JPSS) missions, a series of next-generation polar-orbiting weather observatories.
  • Gravity Recovery And Climate Experiment – Follow-On (GRACE_FO) are a pair of twin satellites to extend measurements from the GRACE satellite, maintaining data continuity. These satellites use microwaves to measure the changes in the Earth’s gravity fields to help map changes in the oceans, ice sheets and land masses. It is planned for launch right at the end of 2017, and is a partnership between NASA and the German Research Centre for Geosciences.

Some of the other launches planned include:

  • Kanopus-V-IK is a small Russian remote sensing satellite with an infrared capability to be used for forest fire detection. It has a 5 m by 5 m spatial resolution over a 2000 km swath, and is planned to be launched next month.
  • Vegetation and Environment monitoring on a New MicroSatellite (VENµS), which is partnership between France and Israel has a planned launch of August. As its name suggests it will be monitoring ecosytems, global carbon cycles, land use and land change.
  • KhalifaSat is the third EO satellite of United Arab Emirates Institution for Advanced Science and Technology (EIAST). It is an optical satellite with a spatial resolution of 0.75 m for the visible and near infrared bands.

Finally, one of the most intriguing launches involves three satellites that form the next part of India’s CartoSat mission. These satellites will carry both high resolution multi- spectral imagers and a panchromatic camera, and the mission’s focus is cartography. It’s not these three satellites that make this launch intriguing, it is the one hundred other satellites that will accompany them!

The Indian Space Research Organisation’s Polar Satellite Launch Vehicle, PSLV-C37, will aim to launch a record 103 satellites in one go. Given that the current record for satellites launched in one go is 37, and that over the last few years we’ve only had around two hundred and twenty satellites launched in an entire year; this will be a hugely significant achievement.

So there you go. Not a fully comprehensive list, as I know there will be others, but hopefully it gives you a flavour of what to expect.

It certainly shows that the EO is not slowing down, and the amount of data available is continuing to grow. This of course gives everyone working in the industry more challenges in terms of storage and processing power – but they are good problems to have. Exciting year ahead!

Is the UK Space Industry in good health?

Blue Marble image of the Earth taken by the crew of Apollo 17 on Dec. 7 1972. Image Credit: NASA

Blue Marble image of the Earth taken by the crew of Apollo 17 on Dec. 7 1972.
Image Credit: NASA

Last week the UK Space Agency issued its latest report on the Size and Health of the UK Space Industry, covering 2013/14 and 2014/15. There are a number of eye-catching headlines, but this broad-brush approach means that there are a lot of unanswered questions within the granularity of the report.

UK Space Industry Income is Worth £13.7 bn in 2014/15
This headline figure breaks down into 88% (£12 bn) for downstream activities. Whilst the 12% (£1.7 bn) for upstream activities is much smaller, it is higher than in previous years. Upstream refers to the part of the industry that build and launch satellites and sensors; whilst downstream encompasses the products and services that use the data those objects collect. Overall, the UK represents 6.5% of global space economy.

Unsurprisingly, given the above breakdown, space applications are the biggest segment of the industry, followed by space operations, space manufacturing and ancillary services.

This follows through into capabilities which are dominated by Broadcasting, Communications and Navigation & Timing which account for 56%, 19.6% and 12.2% of the space industry income respectively. Earth observation is listed with an income of £256 m, equating to 1.87% of the overall industry; although Meteorology is shown separately.

38,522 Jobs in the UK Space Industry in 2014/15
The space industry accounts for 0.12% of the total UK workforce, with 29,947 people working in downstream activities, and 8,575 working in upstream. It’s interesting to note the difference in the employment percentages, 78% and 22% respectively, compared to the income split above.

A fascinating fact in the report is that the average qualification level of space industry employees is higher than any other sector in England and Wales. With 74% of employees possessing a degree, 15% holding a HNC and the remaining 11% having other qualifications.

Space Industry Throughout the UK
All regions of the country have space companies. Of course, London and the South East – partially driven by the Harwell Campus – have the highest concentrations. We were delighted to see that the South West had was the third most populous area with 126 space organisations; although the South West is only fourth for Headquarters and income generated with £176 m worth of space business within the area.

UK Space Industry Customers
The report notes that the largest customer type is individual consumers, accounting for 54% of the income. However, given the domination of Broadcasting in the figures and with the majority of their customers being individual consumers this does skew the result. Equally limited information can be gleaned for the other customer types.

Personally, we’d be interested in seeing the customer type split for each capability. This would be much more useful, as at the moment these are a set of high level figures offering little, or no, insight.

Growth Slowing In the Space Industry?
The report has lots of positive statements about growth. There are at least four different income growth rates of 6.5%, 7.3%, 8.1% and 8.5% on page 10, depending on which time period you compare. Similarly, page 12 on employment lists growth rates of 5.8%, 6.0% and 6.7%.

All of this sounds great, but looking at the growth rates within in the tables for the last 7 years, quite wild swings year on year can be seen. The chart below shows some good growth rates, but the last two years are the lowest growth rates.

UK Space Industry Income & Employment Growth 2009 - 2016. Source: Size & Health of the UK Space Industry 2016, UK Space Agency

UK Space Industry Income & Employment Growth 2009 – 2016.
Source: Size & Health of the UK Space Industry 2016, UK Space Agency

To be fair the report itself notes a few caveats on the figures, such as new methodologies and the changing value of the pound. So care should be taken with such figures, but does it show signs that growth could be slowing for the industry?

Towards 2030 Ambitions
In February 2010 the UK Government set ambitious targets for the industry of:

  • 8% of the world space economy by 2020, and 10% by 2030.
  • 100,000 jobs created by 2030, taking the industry to 119,100

By the end of 2014/15 progress had been made towards both of these targets, with the industry representing 6.5% of the world space economy and having 38,522 jobs. Employment needs to grow by 7.8% each year to achieve the target, which is concerning given the current growth levels outlined above. If jobs aren’t being created, it’s unlikely the global market share target will be hit.

Shaping The Future
Finally, the UK Space Agency is currently seeking ideas and evidence on how to implement the 2015 National Space Policy. Anyone can submit their thoughts, and we’d encourage everyone to participate in helping shape the future of the UK space industry.

The submission document is straightforward asking for proposed actions, alongside evidence as why they are necessary, for each of the four principles of the National Space Policy

  • Space is of strategic importance to the UK because of the value that space programmes deliver back to public services, national security, science and innovation and the economy.
  • Preserving and promoting the safety and security of the unique space operating environment, free from interference.
  • Supporting the growth of a robust and competitive commercial space sector, underpinned by excellent academic research.
  • Cooperating internationally to create the legal frameworks for the responsible use of space and collaborating with other nations to deliver maximum benefit from UK investment in space.

Conclusion
The UK Space Industry is growing, but we need to ensure that we take advantage of every opportunity and develop, promote and encourage the use of space based applications and technology.

With all the concerns about economic certainty in the coming years, let’s make sure our industry rockets ahead!

UK Government View On ESA and Space Industry

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

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

This week we got a glimpse of the UK Government’s view on the space industry, with the publication of Satellites and Space: Government Response to the House of Commons Science & Technology Committee’s Third Report of Session 2016/17. The original report was published in June and contained a series of recommendations, to which the Government responded.

The timing is interesting for two reasons:

  • Firstly, it comes just before the European Space Agency (ESA) Ministerial Council taking place on Thursday and Friday this week in Lucerne. We highlighted the importance of this meeting in a recent blog.
  • Secondly, it has taken the Government five months to respond, something the Committee themselves were disappointed with.

The Government’s response has a number of insights into the future for the UK space industry. The full report can be seen here, but we wanted to pick out three things that caught our eye:

ESA
For us, and the ESA Ministerial, the most interesting comment was that the Government reaffirmed that the UK will remain a member of ESA after Brexit. It also noted that “The UK’s investment in the European Space Agency is an important part of our overall investment in space, from which we obtain excellent value.” Whilst the level of financial commitment to ESA won’t become clear until the Ministerial, the mood music seems positive.

Earth Observation
The role of the Space for Smarter Government Programme (SSGP) was highlighted, particularly in relation to helping the Department for Environment, Food and Rural Affairs use satellite data more. As part of SSGP we ran a successful Flood Mapping project during 2015/16. SSGP is running again this year, but given the importance placed on the programme on embedding space activities within Government it was disappointing not to see a further commitment beyond March 2017.

A business plan for a Government Earth Observation Service is currently being written, which is aimed at increasing the uptake of EO data within Government. We’ve not seen too much about this service yet, and will be very interested in the business plan.

Responding a question on harnessing the public interest in Tim Peake’s time in space, it was nice to see the work of the EO Detective highlighted. This is a fantastic project that raises awareness of the space industry in schools, and uses space/satellite imagery to help children explore topics such as climate change.

Small Satellites
“The Government intends to establish the UK as the European hub for low cost launch of small satellites.” It’s an interesting ambition; although it’s not completely clear what they mean by the term small satellites. As we described last week definitions are important.

On top of the three points above there were some words on funding for space related research; however these amounted to no more than an acknowledgement that various Government bodies will work together. There was also reference to the development of a new Space Growth Strategy, something we’ll talk more about in two weeks.

The Government’s response to this report was an interesting read, and whilst there are still a lot of unanswered questions it does hint at cautious optimism that they will support the space industry.

We were all on tenterhooks this week waiting the big announcements from the ESA Ministerial, and here are some of the headline outcomes:

  • Overall, ESA’s 22 member states plus Slovenia and Canada allocated €10.3 billion for space activities and programmes over the next five years. This includes an EO programme valued at €1.37 bn up until 2025.

Within this overall envelope, the UK has allocated €1.4 bn funding over five years, which equates to 13.5% of total. This includes:

  • €670.5 m for satellite technology including telecommunications, navigation and EO.
  • €376.4 m for science and space research
  • €82,4 m for the ExoMars programme.
  • €71 m for the International Space Station Programme
  • €22 m for innovate space weather missions

Our eye was, of course, drawn to the investment in EO and there is a little more detail, with the €670.5 m is:€60 m for the development of the commercial use of space data €228.8 m for environmental science applications and climate services through ESA’s EO programme, including:

  • Incubed – a new programme to help industry develop the Earth observation satellite technology for commercial markets
  • the Biomass mission to measure the carbon stored in the world’s forests
  • the Aeolus mission, measuring wind speed in three dimensions from space

Finally, it is worth noting Katherine Courtney, Chief Executive of the UK Space Agency, who commented, “This significant investment shows how the UK continues to build on the capability of the UK space sector and demonstrates our continuing strong commitment to our membership in the European Space Agency.”

Ten Top Tips Learnt Working for a Small Remote Sensing Company

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

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

I am approaching the end of my year at Pixalytics, and this blog is summary of what I’ve learnt from working for a small commercial remote sensing company.

The work itself has been a real blessing for me. Remote sensing product development was just the role I had been looking for, so I took it on with relish. During the year I have spent time researching, and supporting the product development of, flood mapping using SAR imagery, vegetation time series and light pollution.

I’ve learnt a huge amount over the past twelve months, and here are my top ten tips on researching & developing remote sensing products:

  1. Keep in mind who your stakeholders are and exactly what they require.
  2. Ensure your ground site is really covered by the satellite image, as coverage tends to be diagonal rather than straightforward latitude and longitude square and can miss a site altogether.
  3. Practise program version control at all times!
  4. Check the images you are using are the best ones for your requirements, i.e., not 16 day composites when daily images are more suitable and available; stopping you wasting a day downloading the wrong images!
  5. Write down problem solving routines, so next time you can do it for yourself!
  6. It’s always important to run pilots and streamline programming. This will save time and effort, and help verify that your end product is statistically robust.
  7. Write down what you find and keep good records of your algorithms and programming, so that you don’t duplicate work.
  8. Write technical notes on your work, so that programs can be easily shared, reviewed and run by others.
  9. Allow sufficient time before deadlines for reviewing and reworking.
  10. Make notes on the data you are using as you go along, including source, dates, locations and any company/organisation credits needed.

These are all lessons I’ll be taking with me when I leave, whether in commerce or academia.

It’s also been an insight into how a business is run, via these activities and hearing (one side!) of Sam’s teleconferences. Plus I’ve been involved in valuable encounters with the Environment Agency on products and have attended conferences, and given a presentation at one, on behalf of Pixalytics.

Plymouth has also been fun to explore. I’ve enjoyed visiting the various arts venues all over the city together with the galleries and museums, festivals and excellent cuisine.

Many thanks to Sam and Andy at Pixalytics for giving me this opportunity. I’m sad to leave and have enjoyed my time here.

Blog written by Dr Louisa Reynolds.

Space is Hard Work!

Pictures showing Sentinel-1A’s solar array before and after the impact of a millimetre-size particle on the second panel. The damaged area has a diameter of about 40 cm. Data courtesy of ESA>

Pictures showing Sentinel-1A’s solar array before and after the impact of a millimetre-size particle on the second panel. The damaged area has a diameter of about 40 cm. Data courtesy of ESA>

Space is unpredictable. Things don’t always go as planned. Over the last few weeks some of the difficulties of working in space have been highlighted.

Gaofen 10
The start of September did not go well for the satellite industry with two failed launches. Firstly, the Chinese Gaofen 10 Earth observation satellite launched on the 31st August onboard the Long March 4C rocket did not appear to have achieved its orbit. The lack of certainty about this is because no official announcement has been made by Chinese authorities, despite pictures of debris appearing on social media the following day. Gaofen-10 was believed to be carrying a multi-polarized C-band SAR instrument and was intended to be part of the China High-Resolution Earth Observation System (CHEOS), joining the existing seven orbiting Gaofen satellites to provide real-time global Earth observations.

SpaceX
The explosion of the SpaceX Falcon rocket on the Cape Canaveral Launchpad received significantly more mainstream media attention than Gaofen 10. This was partly due to the fact it was a SpaceX rocket, and partly because the satellite it carried was going to be used by Facebook. When you have two of the US’s most well-known technology gurus involved, it was bound to grab the headlines.

No-one was hurt, but the satellite was destroyed by the explosion that occurred whilst the rocket was being loaded with fuel; investigations continue into the cause of this. It was an Israeli communication satellite called Amos 6, whose main purpose was the delivery of television channels. However, Facebook also had an agreement to use the satellite to provide internet connectivity to sub-Saharan Africa.

Sentinel-1A Struck in Space
ESA recently confirmed that the Copernicus Sentinel-1A satellite was hit by a millimetre-size particle on one of its solar wings on the 23rd August. The impact caused slight changes to the orientation and orbit of the satellite, although it hasn’t impacted performance.

Engineers were able to activate the onboard cameras, which provided a clear picture of the impact site on the solar panel, which can be seen in image at the top of the blog. The damaged area is approximately 40 centimetres wide, which is consistent with the impact of a fragment of less than 5 millimetres. This damage has reduced the power generated by the solar wing, although the loss will not impact performance as current power generation remains higher than what the satellite requires for routine operations.

It’s not clear whether Sentinel-1A was stuck by space debris or a micrometeoroid. Given the amount of space debris up there significantly larger than 5 millimetres, the potential damage that could be done to satellites is massive!

Back in STEREO
On a more positive note, last month NASA re-established contact with a satellite after a gap of almost two years. In 2006 NASA launched a pair of twin Solar TErrestrial RElations Observatory (STEREO) satellites to provide data about the sun’s solar flares and coronal mass ejections. Contact was lost with STEREO-B (so called because it was orbiting behind STEREO-A; the A signified it was ahead!) on the 1st October 2014 during a routine test. Since that time NASA has been working to re-establish contact with STEREO-B, and amazingly did so on the 21st August 2016!

Having made contact the team are assessing the satellite, and its components, with the hope of bringing it back to working order in the near future.

Close-up of the Philae lander, imaged by Rosetta’s OSIRIS narrow-angle camera on 2 September 2016 from a distance of 2.7 km. The image scale is about 5 cm/pixel. Philae’s 1 m-wide body and two of its three legs can be seen extended from the body. Image courtesy of ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA.

Close-up of the Philae lander, imaged by Rosetta’s OSIRIS narrow-angle camera on 2 September 2016 from a distance of 2.7 km. The image scale is about 5 cm/pixel. Philae’s 1 m-wide body and two of its three legs can be seen extended from the body. Image courtesy of ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/ INTA/UPM/DASP/IDA.

Philae Located!
A second discovery after lost contact is ESA’s Philae Lander! This was the robot that made a historic landing on Comet 67P/Churyumov–Gerasimenko in November 2014, as part of the Rosetta mission. Unfortunately, Philae bounced away from the intended landing site and after a short period of operation, communications were lost. There was brief resurrection in July 2015, before silence returned.

Amazingly, last week the resting site of Philae was finally located with Rosetta’s high resolution camera. It is stuck in a dark crack on the comet surface, explaining why its solar powered batteries were unable to be recharged.

Philae will be joined later this month by the Rosetta probe itself, as it will be crash landed onto the comet. Cameras and chemical sensors will be operating throughout the descent which is planned to take place on the 30th September bringing to end this historic comet chasing mission.

Onward Despite Difficulties
DigitalGlobe’s WorldView 4 satellite is due to be launched on Friday, 16th September aboard an Atlas V rocket from Vandenberg Air Force Base. Like WorldView 3 this satellite should provide imagery with a spatial resolution of 31 cm in panchromatic mode and 1.24 m in multispectral mode.

This shows that despite all of the ups and downs of the last few weeks, the satellite industry keeps moving forward!

Satellite Data Continuity: Hero or Achilles Heel?

Average thickness of Arctic sea ice in spring as measured by CryoSat between 2010 and 2015. Image courtesy of ESA/CPOM

Average thickness of Arctic sea ice in spring as measured by CryoSat between 2010 and 2015. Image courtesy of ESA/CPOM

One of satellite remote sensing’s greatest strengths is the archive of historical data available, allowing researchers to analyse how areas change over years or even decades – for example, Landsat data has a forty year archive. It is one of the unique aspects of satellite data, which is very difficult to replicate by other measurement methods.

However, this unique selling point is also proving an Achilles Heel to industry as well, as highlighted last week, when a group of 179 researchers issued a plea to the European Commission (EC) and the European Space Agency (ESA) to provide a replacement for the aging Cryosat-2 satellite.

Cryosat-2 was launched in 2010, after the original Cryosat was lost during a launch failure in 2005, and is dedicated to the measurement of polar ice. It has a non sun-synchronous low earth orbit of just over 700 km with a 369 day ground track cycle, although it does image the same areas on Earth every 30 days. It was originally designed as three and half year mission, but is still going after six years. Although, technically it has enough fuel to last at least another five years, the risk of component failure is such that researchers are concerned that it could cease to function at any time

The main instrument onboard is a Synthetic Aperture Interferometric Radar Altimeter (SIRAL) operating in the Ku Band. It has two antennas that form an interferometer, and operates by sending out bursts of pulses at intervals of only 50 microseconds with the returning echoes correlated as a single measurement; whereas conventional altimeters send out single pulses and wait for the echo to return before sending out another pulse. This allows it to measure the difference in height between floating ice and seawater to an accuracy of 1.3cm, which is critical to measurement of edges of ice sheets.

SIRAL has been very successful and has offered a number of valuable datasets including the first complete assessment of Arctic sea-ice thickness, and measurements of the ice sheets covering Antarctica and Greenland. However, these datasets are simply snapshots in time. Scientists want to continue these measurements in the coming years to improve our understanding of how sea-ice and ice sheets are changing.

It’s unlikely ESA will provide a follow on satellite, as their aim is to develop new technology and not data continuity missions. This was part of the reason why the EU Copernicus programme of Sentinel satellites was established, whose aim is to provide reliable and up to date information on how our planet and climate is changing. The recently launched Sentinel-3 satellite can undertake some of the measurements of Cryosat-2, it is not a replacement.

Whether the appeal for a Cryosat-3 will be heard is unclear, but what is clear is thought needs to be given to data continuity with every mission. Once useful data is made available, there will be a desire for a dataset to be continued and developed.

This returns us to the title of the blog. Is data continuity the hero or Achilles Heel for the satellite remote sensing community?

Identifying Urban Sprawl in Plymouth

Map showing urban sprawl over last 25 years in the areas surrounding Plymouth

Map showing urban sprawl over last 25 years in the areas surrounding Plymouth

Nowadays you can answer a wide range of environmental questions yourself using only open source software and free remote sensing satellite data. You do not need to be a researcher and by acquiring a few skills you can the analysis of complex problems at your fingertips. It is amazing.

I’ve been based at Pixalytics in Plymouth, over the last few months, on an ERAMUS+ placement and decided to use Plymouth to look at one of the most problematic environmental issues for planners: Urban Sprawl. It is well known phenomenon within cities, but it can’t be easily seen from ground level – you need to look at it from space.

The pressure of continued population growth, the need for more living space, commercial and economic developments, means that central urban areas tend to expand into low-density, monofunctional and usually car-dependent communities with a high negative ecological impact on fauna and flora associated with massive loss in natural habitats and agricultural areas. This change in how land is used around cities is known urban sprawl.

As a city Plymouth suffered a lot of destruction in World War Two, and there was a lot of building within the city in the 1950s and 1960s. Therefore, I decided to see if Plymouth has suffered from urban sprawl over the last twenty-five years, using open source software and data. The two questions I want to answer are:

  1. Is Plymouth affected by urban sprawl? and
  2. If it is, what are Plymouth’s urban sprawl trends?

1) Is Plymouth affected by urban sprawl?
To answer this question I used the QGIS software to analysis Landsat data from both 1990 and 2015, together with OpenStreetMap data for natural areas for a 15 kilometre area starting from Plymouth’s City Centre.

I then performed a Landscape Evolution analysis, as described in Chapter 9 of the Practical Handbook of Remote Sensing, written by Samantha and Andrew Lavender from Pixalytics. Firstly, I overlaid natural areas onto the map of Plymouth, then added the built up areas from 2015 shown in red and finally added the 1990 built-up areas in grey.

Detailed map showing the key urban sprawl around Plymouth over last 25 years

Detailed map showing the key urban sprawl around Plymouth over last 25 years

The map, which has an accuracy of 80 – 85%, shows you, no major urban development occurred in the city of Plymouth and its surroundings in the last 25 years – this is of course about to change the development of the new town of Sherford on the outskirts of the city.

However, as you can see in the zoomed in version of the map on the right, there is a noticeable urban development visible in the north west of the city and a second in Saltash in Cornwall on the east of the map. The built up area in the 15km area around Plymouth increased by around 15% over the 25 year period. The next question is what are the trends of this sprawl.

2) What are Plymouth urban sprawl trends?
A large amount of research tries to categorize urban sprawl in various types:

  • Compact growth which infill existing urban developments, also known as smart growth, and mainly occurs in planning permitted areas
  • Linear development along main roads
  • Isolated developments into agricultural or wildlife areas in proximity with major roads.

These last two have a bad reputation and are often associated with negative impacts on environment.

Various driving forces are behind these growth types, creating different patterns for cities worldwide. For example, rapid economic development under a liberal planning policy drives population growth in a city which then is expands and incorporates villages located in near or remote proximity over time. This is fragmented approach, and results in a strong land loss.

But this is not the case for Plymouth which in the last 25 years showed a stable development in the extend permitted by planning policies with a predominant infill and compact expansion, a smart growth approach that other cities could take as an example.

These conclusions can be taken following only a few simple steps- taking advantage of free open source software and free data, without extensive experience or training.
This is a proven example of how you can make your own maps at home without investing too much time and money.

This is the end my internship with Pixalytics, and it has been one of my best experiences.

Blog written by Catalin Cimpianu, ERASMUS+ Placement at Pixalytics.