Image courtesy of ESA
Note: The debris field shown in the image is an artist’s impression based on actual data. However, the debris objects are shown at an exaggerated size to make them visible at the scale shown
Three news items on satellites caught our attention this week. Firstly, at the end of September, it was announced that the DLR Earth Sensing Imaging Spectrometer (DESIS) was fully operational. This is a hyperspectral imager attached to the exterior of the International Space Station (ISS). It has 235 spectral bands, a spatial resolution of approximately 30 m, although this varies slightly with the ISS orbit, and a swath width of 30 km.
The satellite is a joint venture between the German Space Agency DLR and Teledyne Brown Engineering of Huntsville, Alabama, and it’s estimated that the operational cost is around a third less onboard the ISS than if this was an orbiting satellite. DESIS has been collecting 10 nm spectral resolution hyperspectral imagery since towards the end of last year, however following a further year of testing and calibration it is now able to deliver 2.55 nm hyperspectral imagery
Applications of this data are expected to include evaluating the water quality of water bodies, mapping vegetation types, monitoring vegetation stress, as well as identifying natural resources.  On this last application, it’s reported that DESIS has already identified Neodymium on the Earth’s surface –a rare-earth metal used in electronics – and this is the first time such a metal has been detected from space. The data is available from Teledyne with an archive of around 10 million square kilometres of hyperspectral data, together with the ability to task the imager.
Secondly, at the recent 2019 Aeronautical Society of South Africa Conference which took place in Pretoria between the 16th and 18th October, the chairman of the South Africa company Space Commercial Services (SCS), Sias Mostert, described how South Africa could develop its own Earth Observation satellite using either nano-satellites or micro-satellites developed and built in South Africa.
What was interesting about his talk was the distinction between near-real-time and actual real-time coverage. He estimated that near-real-time coverage of South Africa could be delivered with a relatively small number of satellites for around US$50 million using a similar approach as Copernicus and Landsat. Whereas, actual real-time coverage would take a lot more satellites and estimated that the cost would be between US$200 million and US$400 million. Whilst the fact it would cost more to deliver actual real-time rather than near-real-time is not surprising, the indication that the cost difference is between four and eight times is interesting.
Finally, on the 22nd October Elon Musk claimed he’d successfully sent a tweet via the Starlink network, which SpaceX is establishing to offer internet-based broadband services across the world. Although difficult to know for certain, if true, this could be the beginning of the proof of concept of this service. Currently, there are only 60 satellites in the Starlink constellation which was launched in May this year.
It’s expected that another launch will occur before the end of the year, and multiple launches next year. SpaceX is predicting that it may be able to supply internet broadband services to the United Services by the middle of next year, although there is still work to be done on how individual users will access it.
Originally, SpaceX had predicted that the Starlink constellation would be around 12,000 low Earth orbit satellites. However, it recently submitted documents to US Regulators requesting an additional 30,000 satellites for the constellation! It’s almost unimaginable what this would look like around the planet!
