Blue Holes from Space

Andros Island in The Bahamas. Acquired by Landsat 8 in February 2017. Data courtesy of NASA.

Blue holes are deep marine caverns or sinkholes which are open at the surface, and they get their name from their apparent blue colour of their surface due to the scattering of the light within water. The often contain both seawater and freshwater, and in their depths the water is very clear which makes them very popular with divers.

The term ‘blue hole’ first appeared on sea charts from the Bahamas in 1843, although the concept of submarine caves had been described a century earlier (from Schwabe and Carew, 2006). There are a number of well-known blue holes in Belize, Egypt and Malta amongst others. The Dragon Hole in the South China Sea is believed to be the deepest blue hole with a depth of 300 metres.

The Andros Island in The Bahamas has the highest concentration of blue holes in the world, and last week we watched a television programme called River Monsters featuring this area. The presenter, Jeremy Wade, was investigating the mythical Lusca, a Caribbean sea creature which reportedly attacks swimmers and divers pulling them down to their lairs deep within of the blue holes. Jeremy fished and dived some blue holes, and spoke to people who had seen the creature. By the end he believed the myth of the Lusca was mostly likely based on a giant octopus. Whilst this was interesting, by the end of the programme we were far more interested in whether you could see blue holes from space.

The image at the top is Andros Island. Although, technically it’s an archipelago, it is considered as a single island. It’s the largest island of The Bahamas and at 2,300 square miles is the fifth largest in the Caribbean. There are a number of well known blue holes in Andros, both inland and off the coast, such as:

Blues in the Blue Hole National Park on the Andros Island in The Bahamas. Acquired by Landsat 8 in February 2017. Data courtesy of NASA.

  • Blue Holes National Park covers over 33,000 acres and includes a variety of blue holes, freshwater reservoirs and forests within its boundaries. The image to the right covers an area of the national park. In the centre, just above the green water there are five black circles  – despite the colour, these are blue holes.
  • Uncle Charlie’s Blue Hole, also called Little Frenchman Blue Hole, is just off Queen’s Highway in Nicholls Town and has a maximum depth of 127 metres.
  • Atlantis Blue Hole has a maximum depth of about 85 metres.
  • Stargate Blue Hole his blue hole is located about 500 miles inland from the east coast of South Andros on the west side of The Bluff village.
  • Guardian Blue Hole is in the ocean and is believed to have the second deepest cave in The Bahamas, with a maximum explored depth of 133 metres.

Blue hole in the south of Andros Island in The Bahamas. Acquired by Landsat 8 in February 2017. Data courtesy of NASA.

The image to the right is from the south of the island. Just off the centre, you can see a blue hole surrounded by forests and vegetation.

So we can confirm that the amazing natural features called blue holes can be seen from space, even if they don’t always appear blue!

Monitoring Fires From Space

Monitoring fires from space has significant advantages when compared to on-ground activity. Not only are wider areas easier to monitor, but there are obvious safety benefits too. The different ways this can be done have been highlighted through a number of reports over the last few weeks.

VIIRS Image from 25 April 2017, of the Yucatán Peninsula showing where thermal bands have picked-up increased temperatures. Data Courtesy of NASA, NASA image by Jeff Schmaltz, LANCE/EOSDIS Rapid Response.

Firstly, NASA have released images from different instruments, on different satellites, that illustrate two ways of how satellites can monitor fires.

Acquired on the 25 April 2017, an image from the Visible Infrared Imaging Radiometer Suite (VIIRS) on the Suomi NPP satellite showed widespread fire activity across the Yucatán Peninsula in South America. The image to the right is a natural colour image and each of the red dots represents a point where the instrument’s thermal band detected temperatures higher than normal.

False colour image of the West Mims fire on Florida/Georgia boundary acquired by MODIS on 02 May 2017. Data courtesy of NASA. NASA image by Jeff Schmaltz, LANCE/EOSDIS Rapid Response.

Compare this to a wildfire on Florida-Georgia border acquired from NASA’s Aqua satellite on the 02 May 2017 using the Moderate Resolution Imaging Spectroradiometer (MODIS). On the natural colour image the fires could only be seen as smoke plumes, but on the left is the false colour image which combines infrared, near-infrared and green wavelengths. The burnt areas can be clearly seen in brown, whilst the fire itself is shown as orange.

This week it was reported that the Punjab Remote Sensing Centre in India, has been combining remote sensing, geographical information systems and Global Positioning System (GPS) data to identify the burning of crop stubble in fields; it appears that the MODIS fire products are part of contributing the satellite data. During April, 788 illegal field fires were identified through this technique and with the GPS data the authorities have been able to identify, and fine, 226 farmers for undertaking this practice.

Imaged by Sentinel-2, burnt areas, shown in shades of red and purple, in the Marantaceae forests in the north of the Republic of Congo.
Data courtesy of Copernicus/ESA. Contains modified Copernicus Sentinel data (2016), processed by ESA.

Finally, a report at the end of April from the European Space Agency described how images from Sentinel-1 and Senintel-2 have been combined to assess the amount of forest that was burnt last year in the Republic of Congo in Africa – the majority of which was in Marantaceae forests. As this area has frequent cloud cover, the optical images from Sentinel-2 were combined with the Synthetic Aperture Radar (SAR) images from Sentinel-1 that are unaffected by the weather to offer an enhanced solution.

Sentinel-1 and Sentinel-2 data detect and monitor forest fires at a finer temporal and spatial resolution than previously possible, namely 10 days and 10 m, although the temporal resolution will increase to 5 days later this year when Sentinel-2B becomes fully operational.  Through this work, it was estimated that 36 000 hectares of forest were burnt in 2016.

Given the danger presented by forest fires and wildfires, greater monitoring from space should improve fire identification and emergency responses which should potentially help save lives. This is another example of the societal benefit of satellite remote sensing.

China’s Geo-Information Survey

Yuqiao Reservoir, east of Beijing, China from Landsat 8 acquired March 2017. Data courtesy of NASA/USGS,.

The first national geo-information study of China was released last week at a State Council Information Office press briefing.

The study, also referred to as the national census of geographic conditions, was originally announced in March 2013. Over the last three years 50,000 professionals have been involved in collecting a variety of data about China and it’s reported that they have achieved a 92% coverage of the country, generating around 770 terabytes of data in the process.

Data has been collected on natural resources, such as land features, vegetation, water and deserts; together with urban resources such as transport infrastructure, towns and neighbourhoods. This information was gathered, and verified, through remote sensing satellites, drones, aerial photography, 3D laser scanning and in-situ data. It’s reported that the accuracy is 99.7% with a 1 m resolution.

China is one of the largest countries in the world by land mass, at approximately 9.6 m square kilometres. Therefore, simply completing such a study with the accuracy and resolution reported is highly impressive.

It may take years to fully appreciate the variety, size and usefulness of this new dataset. However, a number of interesting high level statistics have already been released by the Chinese Ministry of Land and Resources including:

  • 23.2% of China’s land is above 3,500 m altitude, and 43.4% is below 1,000 m altitude.
  • 7.57 million sq km of the country has vegetation cover, with 21.1% being cultivated lands and the remainder grasslands and forests.
  • 1.3 million sq km of land is desert and bare lands, whilst rivers cover 6.55 million sq km.
  • 153,000 sq km of land has buildings on it.
  • 116,500 sq km of railway track and there is 2 million sq km of roads.

According to Kurex Mexsut, deputy head of the National Administration of Surveying, Mapping and Geoinformation, the Chinese Government will be looking to establish a data sharing mechanism and information services platform for this dataset, together with a variety of data products. It is hoped that public departments and companies will be able to use this to help improve the delivery of public services.

Although not from the survey, the image at the top is of the Yuqiao Reservoir, situated just to the east of Beijing. It has a surface area of 119 sq km, with an average depth of 14 metres.

Not only is this a comprehensive geo-information dataset for a single country, but there is also huge potential for further information to be derived from this dataset. We’ll be watching with interest to see how the data is used and the impact it has.

Three Exciting Ways to Protect Forests With Remote Sensing

Forests cover one third of the Earth’s land mass and are home to more than 80% of the terrestrial species of animals, plants and insects. However, 13 million hectares of forest are destroyed each year. The United Nations International Day of Forests took place recently, on 21st March, to raise awareness of this vital resource.

Three remote sensing applications to help protect forests caught our eye recently:

Two scans show the difference between infected, on the right, and uninfected, on the left, patches of forest. Image Courtesy of University of Leiceste

Identifying Diseased Trees
In the March issue of Remote Sensing, researchers from the University of Leicester, (Barnes et al, 2017), published a paper entitled ‘Individual Tree Crown Delineation from Airborne Laser Scanning for Diseased Larch Forest Stands’. It describes how the researchers were able to identify individual trees affected by larch tree disease, also known as phytophthora ramorum.

This fungus-like disease can cause extensive damage, including the death, and diseased trees can be identified by defoliation and dieback. Airborne LiDAR surveys were undertaken by the company Bluesky at an average altitude of 1500 m, with a scan frequency of 66 Hz that gave a sensor range precision within 8 mm and elevation accuracy around 3–10 cm.

Remote sensing has been used to monitor forests for many years, but using it to identify individual trees is uncommon. The researchers in this project were able to successfully identify larch canopies partially or wholly defoliated by the disease in greater than 70% of cases. Whilst further development of the methodology will be needed, it is hoped that this will offer forest owners a better way of identifying diseased trees and enable them to respond more effectively to such outbreaks.

Monitoring Trees From Space
An interesting counterpoint to work of Barnes et al (2017) was published by the journal Forestry last month. The paper ‘Estimating stand density, biomass and tree species from very high resolution stereo-imagery – towards an all-in-one sensor for forestry applications‘ written by Fassnacht et al (2017).

It describes work undertaken to compare the results of very high resolution optical satellite data with that of airborne LiDAR and hyperspectral data to provide support for forestry management. The team used WorldView-2 images, of a temperate mixed forest in Germany, with a 2m pixel size, alongside a LiDAR DTM with a 1 m pixel size. This data was then used to estimate tree species, forest stand density and biomass.

They found  good results for both forest stand density and biomass compared to other methods, and although the tree classification work did achieve over eighty percent, this was less than achieved by hyperspectral data over the same site; although differentiation of broadleaved and coniferous trees was almost perfect.

This work shows that whilst further work is needed, optical data has the potential to offer a number of benefits for forestry management.

Monitoring Illegal Logging
Through the International Partnership Programme the UK Space Agency is funding a consortium, led by Stevenson Astrosat Ltd, who will be using Earth Observation (EO) data to monitor, and reduce, illegal logging in Guatemala.

The issue has significant environmental and socioeconomic impacts to the country through deforestation and change of land use. The Guatemalan government have made significant efforts to combat the problem, however the area to be monitored is vast. This project will provide a centralised system using EO satellite data and Global Navigation Satellite Systems (GNSS) technology accessed via mobile phones or tablets to enable Guatemala’s National Institute of Forestry (INAB) to better track land management and identify cases of illegal logging.

Overall
The protection of our forests is critical to the future of the planet, and it’s clear that satellite remote sensing can play a much greater role in that work.

Catching Wavelength 2017

Remote sensing, like GIS, excels in integrating across disciplines and people. Whilst no one ever said being a multi-disciplinary scientist was going to be easy, for the ‘thirsty’ mind it challenges, cross pollinates ideas and looks at problems with new eyes. A diverse group of people connected by a common thread of spatial and remotely sensed data found themselves doing all these things and more in London last week at the Wavelength 2017 conference.

The talks and posters took us on whirlwind tour through the ever varying landscape of remote sensing. We moved through subject areas ranging from detecting ground ice, vegetation and overall land cover, through to earth surface movement and 3D imaging, and onto agriculture yield and drought. We also covered the different vertical scales from which remotely sensed data is collected, whether from satellites, planes, drones or cameras operated from ground level. On top of this focus we also had some great key note talks, running through the varied career of a remote sensing scientist (Groeger Ltd), as well as in depth data assimilation of remote sensing imagery in models (UCL) and commercial developments in airborne camera work (Geoxphere Ltd).

In parallel, we were taken on a grand tour covering the temperate UK, parts of the Middle East, the tundra in North America, the central belt of Africa, and even onto the moon and Mars! In many cases we heard talks from scientists from these countries (though not the moon or Mars …). Some are based at the universities in the UK, whilst, others came specifically to talk at the conference.

I found myself transfixed by the far flung places. Listening to how the dark side of the moon is being mapped, a place that never sees daylight and is incredibly ‘chilly’ and traps ice in these shadowed lands. I also heard about the CO2 that precipitates out of the atmosphere on Mars as snow and forms a 1m blanket. Working in places like Africa started to feel really quite local and accessible!

Possibly the most intriguing aspect of the conference for me, was the advancements that have been made in photogrammetry and how multiple photos are now being used to produce highly intricate 3D models. We saw this applied to cliff morphology and change detection, as well as the 3D point clouds that are produced when modelling trees and vegetation generally.

The 3D models aren’t totally complete due to line of sight and other issues. The model visualisations look like an impressionist painting to me, with tree leaves without trunks or clumps of green mass suspended in mid air. However, this does not matter when calculating leaf volume and biomass, as these discrepancies can be worked with and lead to some very useful estimates of seasonality and change.

Setting this up is no small feat for the organiser, and PhD student, James O’Connor. He delivered an interesting programme and looked after the delegates well. I can truly say I haven’t been to such a friendly conference before. It was also unique in providing ample time to discuss aspects of material presented, both from talks and posters, and sharing technical know-how. This felt of real value, especially to the PhD students and young professionals this conference is geared towards, but equally myself with experience in only certain fields of remote sensing.

I would highly recommend Wavelength, and look forward to seeing what they are planning for 2018!

Blog written by Caroline Chambers, Pixalytics Ltd.

Remote Sensing Goes Cold

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

Remote sensing over the Polar Regions has poked its head above the ice recently.

On the 8th February The Cryosphere, a journal of the European Geosciences Union, published a paper by Smith et al titled ’Connected sub glacial lake drainage beneath Thwaites Glacier, West Antarctica’. It described how researchers used data from ESA’s CryoSat-2 satellite to look at lakes beneath a glacier.

This work is interesting from a remote sensing viewpoint as it is a repurposing of Cryosat-2’s mission. It’s main purpose is to measure the thickness of the ice sheets and marine ice cover using its Synthetic Aperture Radar (SAR)/Interferometric Radar Altimeter, known as SIRAL, and it can detect millimetre changes in the elevation of both ice-sheets and sea-ice.

The team were able to use this data to determine that the ice of the glacier had subsided by several metres as water had drained away from four lakes underneath. Whilst the whole process took place between June 2012 and January 2014, the majority of the drainage happened in a six month period. During this time it’s estimated that peak drainage was around 240 cubic metre per second, which is four times faster than the outflow of the River Thames into the North Sea.

We’ve previously highlighted that repurposing data – using data for more purposes than originally intended – is going to be one of the key future innovation trends for Earth Observation.

Last week, ESA also described how Sentinel-1 and Sentinel-2 data have been used over the last five months to monitor a crack in the ice near to the Halley VI research base of the British Antarctic Survey (BAS). The crack, known as Halloween Crack, is located on the Brunt ice Shelf in the Wedell Sea sector of Antarctica and was identified last October. The crack grew around 600 m per day during November and December, although it has since slowed to only one third of that daily growth.

Since last November Sentinel-2 has been acquiring optical images at each overflight, and this has been combined with SAR data from the two Sentinel-1 satellites. This SAR data will be critical during the Antarctic winter when there are only a few hours of daylight and a couple of weeks around mid-June when the sun does not rise.

This work hit the headlines as BAS decided to evacuate their base for the winter, due to the potential threat. The Halley VI base, which was only 17km from the crack, is the first Antarctic research station to be specifically designed to allow relocation to cope with this sort of movement in the ice shelf. It was already planned to move the base 23 km further inland, and this was successfully completed on the 2nd February. Further movement will depend on how the Halloween Crack develops over the winter.

Finally, the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) project was announced this week at the annual meeting of the American Association for the Advancement of Science. Professor Markus Rex outlined the project, which will sail a research vessel into the Arctic sea ice and let it get stuck so it can drift across the North Pole. The vessel will be filled with a variety of remote sensing in-situ instruments, and will aim to collect data on how the climate is changing in this part of the world through measuring the atmosphere-ice-ocean system.

These projects show that the Polar Regions have a lot of interest, and variety, for remote sensing.

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.

Have you read the top Pixalytics blogs of 2016?

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

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

As this is the final blog of the year we’d like to take a look back over the past fifty-two weeks and see which blog’s captured people’s attention, and conversely which did not!

It turns out that seven of the ten most widely viewed blogs of the last year weren’t even written in 2016. Four were written in 2015, and three were written in 2014! The other obvious trend is the interest in the number of satellites in space, which can be seen by the titles of six of the ten most widely read blogs:

We’ve also found these blogs quoted by a variety of other web pages, and the occasional report. It’s always interesting to see where we’re quoted!

The other most read blogs of the year were:

Whilst only three of 2016’s blogs made our top ten, this is partly understandable as they have less time to attract the interest of readers and Google. However, looking at most read blogs of 2016 shows an interest in the growth of the Earth Observation market, Brexit, different types of data and Playboy!

We’ve now completed three years of weekly blogs, and the views on our website have grown steadily. This year has seen a significant increase in viewed pages, which is something we’re delighted to see.

We like our blog to be of interest to our colleagues in remote sensing and Earth observation, although we also touch on issues of interest to the wide space, and small business, communities.

At Pixalytics we believe strongly in education and training in both science and remote sensing, together with supporting early career scientists. As such we have a number of students and scientists working with us during the year, and we always like them to write a blog. Something they’re not always keen on at the start! This year we’ve had pieces on:

Writing a blog each week can be hard work, as Wednesday mornings always seem to come around very quickly. However, we think this work adds value to our business and makes a small contribution to explaining the industry in which we work.

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

We’d like to wish everyone a Happy New Year, and a very successful 2017!

Perspectives from the 12th Appleton Space Conference

Sam presenting at the 2016 Appleton Space Conference. Image courtesy of Deimos UK.

Sam presenting at the 2016 Appleton Space Conference. Image courtesy of Deimos UK.

Last week I attended the 12th Appleton Space Conference, it was the first time I’d been to one of these conferences, and I was excited to be giving a talk. It was hosted by RAL Space at the Harwell Campus.

After the welcome, the day started with a talk from Ross James (Deputy CEO at the UK Space Agency). He’s new to the space community, and so has enjoyed learning to understand it more fully. It was interesting to hear him reinforce the conclusion that the space industry’s value-added multiplier is two, but also that the industry needs to be more regionally and user focused.

Talks then followed by members of European Centre for Space Applications and Telecommunications (ECSAT, the UK’s ESA centre) and the Harwell Campus. I was surprised hear the comparison that the Harwell Campus site is roughly equivalent to the size of the City of London. Whilst Harwell doesn’t yet have any of the iconic tall buildings of the City, it does mean it has plenty of space to grow – with plans to increase the campus to 5 500 jobs by 2020; although it was acknowledged that an upgrade of the underpinning infrastructure would be needed to support this.

Sam presenting at the 2016 Appleton Space Conference. Image courtesy of Sara Huntingdon, Space for Smarter Government Programme.

Sam presenting at the 2016 Appleton Space Conference. Image courtesy of Sara Huntingdon, Space for Smarter Government Programme.

After the break we swapped to the topics of growth and innovation. The Autumn Statement had a strong focus on creating an environment for backing winners, with Innovation UK targeted on turning scientific excellence into economic input and scaling up high potential businesses. Two quotes from Tim Just (Innovate UK) that particularly resonated with me:

  • Research is the transformation of money into knowledge; and
  • Innovation transforms it back again.

There was also a debate on whether the space industry is reaching the threshold for a tipping point as outlined in Malcolm Gladwell’s criteria – i.e., where a slow moving trend reaches critical mass and causes a larger change such as the use of space applications and technologies becoming the everyday norm. The last two talks before lunch were on the development of new instruments – including the recently launched Sentinel-3 mission.

The first afternoon session was on understanding scientific advances. We started off by discussing exoplanets (a planet which orbits a star outside the solar system), followed by detecting signals using ground based radars and then understanding gravitational waves. My own talk on harnessing the increasing volumes of Earth Observation (EO) data came at the end of this session. I focused on discussing how there has been a massive change in the amount of available EO data with the need to bring the abilities of computers and humans together to best use this wealth of information.

The slides from my presentation can be found here. It was interesting to see some of the messages people took away from my talk on Twitter such as:

  • The availability of free satellite data is revolutionising remote sensing
  • We have to make the most out of the large quantity of data made available by Earth Observation

After lots of people coming to talk to me during coffee it was great to see Paul Jerram from e2V showing what EO sensors look like, ranging from much larger version of the snapshot imagers found in smart phones to time delay imagers that collect the signal over a period of time so we can have very high resolution imagery. For example, the planet Mars is being imaged at 30 cm resolution. Prof Martin Wooster (Kings College London) focused on biomass burning emissions. Research has shown that the Malaysian fires in 2015, linked to El Nino, contributed to 15% of the global carbon dioxide increases that year but also to thousands of deaths due to the air pollution they caused.

Our day of talks concluded with a keynote lecture by Tim Peake, giving a personal insight into his mission into Space onboard the International Space Station (ISS). As an afternoon speaker I had a front row seat, and so I’m easily spotted on Tim’s room selfie! It was interesting to hear that Tim found adjusting to gravity back on Earth more difficult than weightlessness in space. How much he enjoyed his time on the ISS was obvious when he said he’d be happy to go again as the journey into space was particularly exhilarating.

Whilst aboard the ISS Tim used his limited amount of spare time on Sundays to take photographs of the Earth. Anyone who followed Tim on Twitter will have seen some of these, but he has also now brought out a book of these pictures titled ‘Hello, is this planet Earth? My View from the International Space Station’. An interesting footnote, although not from the conference, is that the UK has just purchased the capsule Tim used to get to, and from, space and it will go on display in the Science Museum next year.

Overall, it was a fantastic day jam packed with interesting, exciting and inspiring discussions about space!

Small Satellites Step Forward

Artist's concept of one of the eight Cyclone Global Navigation Satellite System satellites deployed in space above a hurricane. Image courtesy of NASA.

Artist’s concept of one of the eight Cyclone Global Navigation Satellite System satellites deployed in space above a hurricane. Image courtesy of NASA.

We’re all about small satellites with this blog, after looking at the big beast that is GOES-R last week. Small satellites, microsatellites, cubesats or one of the other myriad of names they’re described as, have been in the news this month.

Before looking at what’s happening, we’re going to start with some definitions. Despite multiple terms being used interchangeably, they are different and are defined based around either their cubic size or their wet mass – ‘wet mass’ refers to the weight of the satellite including fuel, whereas dry mass is just the weight of satellite:

  • Small satellites (smallsats), also known as minisats, have a wet mass of between 100 and 500 kg.
  • Microsats generally have a wet mass of between 10 and 100 kg.
  • Nanosats have a wet mass of between 1 and 10 kg.
  • Cubesats are a class of nanosats that have a standard size. One Cubesat measures 10x10x10 cm, known as 1U, and has a wet mass of no more than 1.33 kg. However, it is possible to join multiple cubes together to form a larger single unit.
  • Picosats have a wet mass of between 0.1 and 1 kg
  • Femtosats have a wet mass of between 10 and 100 g

To give a comparison, GOES-R had a wet mass of 5 192 kg, a dry mass of 2 857 kg, and a size of 6.1 m x 5.6 m x 3.9 m.

Small satellites have made headlines for a number of reasons, and the first two came out of a NASA press briefing given by Michael Freilich, Director of NASA’s Earth science division on the 7th November. NASA is due to launch the Cyclone Global Navigation Satellite System (CYGNSS) on 12th December from Cape Canaveral. CYGNSS will be NASA’s first Earth Observation (EO) small satellite constellation. The mission will measure wind speeds over the oceans, which will be used to improve understanding, and forecasting, of hurricanes and storm surges.

The constellation will consist of eight small satellites in low Earth orbits, which will be focussed over the tropics rather than the whole planet. Successive satellites in the constellation will pass over the same area every twelve minutes, enabling an image of wind speed over the entire tropics every few hours.

Each satellite will carry a Delay Doppler Mapping Instrument (DDMI) which will receive signals from existing GPS satellites and the reflection of that same signal from the Earth. The scattered signal from the Earth will measure ocean roughness, from which wind speed can be derived. Each microsatellite will weigh around 29 kg and measure approximately 51 x 64 x 28 cm; on top of this will be solar panels with a span of 1.67 m.

The second interesting announcement as reported by Space News, was that NASA is planning to purchase EO data from other small satellite constellation providers, to assess the quality and usability of that data. They will be one-off purchases with no ongoing commitment, and will sit alongside data from existing NASA missions. However, it is difficult not to assume that a successful and cost effective trial could lead to ongoing purchases, which could replace future NASA missions.

It’s forecast that this initiative could be worth in the region of $25 million, and will surely interest the existing suppliers such as Planet or TerraBella; however, in the longer term it could also attract new players to the market.

Finally in non NASA small satellite news, there was joint announcement at the start of the month by the BRICS states (Brazil, Russia, India, China and South Africa) that they’d agreed to create a joint satellite constellation for EO. No further detail is available at this stage.

Once again, this shows what a vibrant, changing and evolving industry we work in!