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| Source: BBC (accessed from https://images.app.goo.gl/hHFDyxHaTdDYWzd98 on 17.05.2019) |
The recent BBC and Open University collaboration Earth from Space explored a range of natural and human phenomenon which can be observed from space through satellite imagery, which, when combined with aerial footage and camera work on the ground provided an insight into four key areas:
- Investigating the Earth from a new perspective
- Patterns visible on the planet
- Colours found across the planetary surface
- The ways in which changes on the Earth's surface may be observed
Whist there was some focus on the impact of humans upon the planet - from cultural exhibitions within China to the presence of large-scale agri-business - the majority of the focus was on the use of Earth Observation for the natural world, of which remote sensing does have a long and illustrious history. However, by focusing so heavily on natural process are we missing out on some of the benefits which can be gleaned from space technologies to analyse very human problems. Or can be investigate these human issues in relation to their detrimental impact on ecosystems. As some things overlooked within the world of remote sensing and I thought I would take the time to explore a few of them here.
The Democratisation of Space Technologies
Throughout the documentary series we were treated to a variety of highly detailed imagery which come at a cost to the average user. Very high spatial resolution which such detail is often associated with commercial data providers such as DigitalGlobe and Airbus. However, the majority of users investigating impacts upon the Earth's surface are not able to access these images due to their high associated costs. Open access to these data are therefore extremely important (see the importance of this access here). There are however a growing range of open access data sources, predominantly from governmental platforms. These sensors are often medium-spatial resolution and have a longevity of data collection which is unrivalled at present by the commercial providers. NASA's Landsat programme has a time series closing in on half a century of data within the archive and this is now being supported by the comparable Copernicus programme from the European Space Agency (ESA) - creating a virtual constellation of satellites securing global data collection with free access for all.
Additionally, the growth of 'SmallSats' is enabling students to launch their own remote sensing technologies, but this is also allowing companies to make use of smaller technologies with lower build and operational costs to create true constellations of EO satellites. Planet Labs is a good example of this where they collect high-spatial resolution data (at approx. 3m) with their most common satellite known as the Dove. These data are therefore less expensive than imagery from larger commercial providers due to the lower resolution, however their imagery has a much higher level of detail than say ESA's Sentinels (10m) and Landsat (30m). Moreover, commercial providers are engaging in partnership with the humanitarian, conservation and education sectors, amongst others, in order to develop the applications for the data, expand knowledge, and support in the growth of the space technology sector.
Alternative forms of Earth Observation
Earth from Space displayed a variety of unique observation of the Earth, from pockets of melting water on the ice caps to wildfires in California, and the development of agricultural practices for palm oil in Indonesia (causing deforestation) to the expansion of the suburbs of Las Vegas. All of these views demonstrated the power of human impact and also showed the wonderful patterns exhibited in both the natural and human realms. These displays were all shown in the visible part of the electromagnetic spectrum - as an optical image. This meant that the observations which utilise the rest of the spectrum were overlooked, despite the fact they can also provide vast swaths of information pertinent to the understanding of the Earth's systems.
False Colour Composites
During the investigation of vegetation across the planet, the combination of a false colour display enables the identification of trends and changes across the seasons, and also display areas where agriculture is thriving or where deforestation has occurred. This display includes the 'green' 'red' and 'near-infrared' bands. This unique display highlights the vegetation in a bright and vibrant red, with the combination of bands being vital in the investigation of vegetation health and coverage through a NDVI analysis.
Atmospheric Analysis
Remote sensing - particularly related to the human impacts, as was the focus of much of the documentary - is not just focused on the surface of the Earth. This was briefly touched upon in Episode 4 which looked a the formation and landfall of tropical storms using data for the geostationary meteorological satellites. Meteorology and atmospheric investigation are an important avenue of research within science, especially as the effects of the climate crisis take hold. These concerns have been reflected in the launch and operation of more atmospheric satellites, such as Sentinel 5 (Copernicus programme). Data continue to be collected by a range of sensors regarding the distribution of pollutants including carbon dioxide levels, ozone distribution to monitor the danger of the ozone hole, and nitrogen dioxide levels amongst others. These data are vital as we contend with the current climate crisis, and increasing our knowledge and evidence-base allows for strategic policy design to limit the levels of pollutants in high-emission zones, locate the causes of these pollutants and monitor the progress of emissions reduction.
Similar principles can also be applied to the monitoring of sea and land temperatures. Ice sheets are also monitored extensively using satellite imagery due to the remote location and inaccessibility. Climate science is subsequently and area of research in which satellite data is vital to understand the scale of the issue fully and begin to tackle the global problem.
LiDAR
As noted previously, optical remote sensing is not the only form of remotely sensed data which we can collect. LiDAR (light detecting and ranging) is an increasingly used methodological approach which enables the investigation of environments through the pulse of a laser. These techniques are airborne at the moment, with the exception of a sensor on-board the International Space Station (ISS). These data also have a range of applications from elevation change to monitoring of biomass in forests.
Remote sensing must be thought of as a range of tools with varying applications; displaying and analysing the data are unique to the problem being investigated and the technical ability and resources accessible to the users. Whilst a variety of observations were shown in Earth from Space, it is worth bearing in mind that there are a variety of other remotely sensed data available to meet the needs of the user, more than have been noted here even.
Remote Sensing to Help Humans
The implications of human activity were extensively explored throughout the series providing a unique insight into the sometimes interesting, more often than not devastating impacts humans have had on our planet. However, the impacts of humans is something which remote sensing research has only relatively recently begun to take seriously. Humanitarian mapping through crowdsourcing activities is now commonplace after a natural disaster (see the activities of Humanitarian OpenStreetMap), and this is supported by the implementation of the International Disasters Charter - whereby satellite imagery providers collect and provide data for free over areas which have been damaged in order to aid rescue operations.
Remote sensing has also been extensively used in the human rights sector since the early 2000s with commercial providers supporting large non-governmental organisations (NGOs) such as Amnesty International, and Human Rights Watch; they are also being applied by educational organisations for the same reasons; see the Harvard Humanitarian Initiative and the Rights Lab (University of Nottingham) - where the application of satellite imagery is being used to investigate the very specific issue of modern slavery as part of the Data Programme.
Earth Observation is one of the greatest innovations of our time. We have already been able to learn much about the implications of human and natural activity upon out planet over the past 40+ years. Developments in technology have allowed, and will continue to enable, the increased understanding of the Earth's systems, what is being affected by climate change, and determine strategies which can be put in place to mitigate and perhaps even reverse the effects which have been shown. As temporal re-visit rates reduce, data becomes more easily accessible and the detail of the imagery increases we should be able to glean even more information about our home. Earth from Space highlighted some of the amazing work that has already been achieved using remotely sensed data, and hopefully it also introduced the concept of remote sensing to the masses in a way that piqued their interest, hopefully leading to further investigation of the ways our planet can be observed.
Earth from Space is still available to view on BBC iPlayer (UK only)
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