Duncan Steel

Duncan Steel is a space scientist based in Nelson. He has worked in scientific research for over forty years, with times spent with NASA, ESA, various universities and observatories, and also running his own company. Duncan is the author of four books, over a hundred research papers, and more than a thousand articles for newspapers and magazines. He has also appeared in hundreds of radio and TV programmes. Minor planet/ asteroid (4713) Steel is named for him, as is a lunar-roving robot in one of Arthur C. Clarke's SciFi novels.

The Nelson bush fire: What can satellite images tell us about such events? - Out of Space

Feb 12, 2019

[avatar user=”duncansteel” size=”thumbnail” align=”right” /] The ongoing fires in the Nelson-Tasman region have quite rightly provoked much alarm. The response of Fire and Emergency New Zealand, the NZ Police, the NZ Defence Force, and many private individuals, has been magnificent. However, the utilisation of satellite imagery for assessing such fires and then planning and responding is deficient in NZ compared to much of the rest of the developed world, where such information is used as a matter of course. In the post below I illustrate what can be done… and my own mistakes.    I remember once reading a letter to the editor of The Times in which the correspondent lamented that Latin was no longer taught at most schools. He told the tale of having once erred whilst driving, almost colliding with another car which had the right of … Read More

Satellite imagery of the Nelson bush fire - Out of Space

Feb 09, 2019

[avatar user=”duncansteel” size=”thumbnail” align=”right” /] The area burnt in the ongoing bush fire in the Nelson-Tasman region, largely around Pigeon Valley near Wakefield, can easily be seen in satellite imagery collected in recent days.  Earth observation satellites frequently cross New Zealand and, clouds allowing, collect imagery of the land and sea below. In later posts I will discuss such data collection in more detail, but the specific intent of this post is to make easily available some imagery showing the area burnt in the ongoing Nelson-Tasman bush fire. There are many potential free sources of satellite imagery, though of course one needs to know where to access the data, and how to process the images in order to get your desired results. I have been doing such things for some years, and so am well-practised, but downloading and massaging the … Read More

Satellite Orbits: Global Navigation Systems - Out of Space

Feb 05, 2019

[avatar user=”duncansteel” size=”thumbnail” align=”right” /] Apart from the US-provided Global Positioning System (GPS) used by most commercial navigation systems – such as in your car, or mobile phone – there are several distinct networks operated by other space agencies deploying their own satellite fleets. Here I describe the orbits employed by the Russian, European Union and Chinese GNSS constellations. (Part 3 in a series of posts concerning satellite orbits.)   My previous post concerned the US Global Positioning System (GPS), which uses a constellation of at least 24 satellites (currently 31 operational) to provide worldwide high-precision positional location. This is the GNSS (Global Navigation Satellite System) that many of us use daily in our mobile electronic devices. There are other satellite fleets that have been assembled to deliver the same sort of service, however, and in the … Read More

Harry Hindmarsh Atkinson: obituary - Out of Space

Jan 27, 2019

Harry Atkinson in 2012 (courtesy William Tobin). Harry Atkinson was one of those able New Zealanders who went overseas to study, fully intending to return one day to these shores to live, but due to their great success in their adopted homelands never did so. A physicist by training, he moved into science advice and administration in Britain and rose to considerable heights both within the UK Government and also international organisations such as the European Space Agency. Dr Harry Hindmarsh Atkinson (HHA) was born in Wellington and came from a prominent NZ family, his paternal grandfather being Harry Albert Atkinson (HAA), four-time Prime Minister between 1876 and 1891. The Atkinsons were related by marriage to the Richmond family (see also here), who were also active in politics. HAA had three children by his second wife, the … Read More

Satellite Orbits: Global Positioning System - Out of Space

Jan 24, 2019

[avatar user=”duncansteel” size=”thumbnail” align=”right” /] Most of us use GPS everyday in some way, either driving in our cars or finding our way on a map displayed on our smart phones as we walk around town. Few know what sorts of orbits are occupied by the satellites making all this possible, though. (Part 2 in a series of posts concerning satellite orbits.)   In a previous post I described satellites in geostationary orbit, these remaining above one point on the equator and being used for radio communications or whole-disk imaging of the Earth for meteorological and other purposes. Such satellites take precisely one sidereal day (almost four minutes short of a mean solar day) to orbit the planet, travelling at a speed just above 3 km/sec (11,000 kph). The geostationary altitude is around 35,790 km above the equator, … Read More

The invention of the geostationary communications satellite - Out of Space

Jan 18, 2019

[avatar user=”duncansteel” size=”thumbnail” align=”right” /] The idea of satellites beaming radio communications around the globe was discussed by science-fiction author Arthur C. Clarke in 1945, though he imagined huge geostationary space stations permanently staffed by astronauts who would be needed to change the electronic valves in the onboard radio transmitters. We’ve not been able to watch live cricket matches from around the globe on television for very long. When I was a child in the UK in the 1960s we would need to wait for days for film of major events in the US to be flown across the Atlantic and shown on TV. After I first arrived in New Zealand in 1982, highlights of British football games played on a Saturday were shown on TV the Sunday afternoon eight days later – unless the tape missed the flights … Read More

Satellite Orbits: Geostationary - Out of Space

Jan 16, 2019

[avatar user=”duncansteel” size=”thumbnail” align=”right” /] What sorts of orbits around Earth do we use for different types of satellite, and why are those paths chosen? In this, Part 1 in a series of blog posts, geostationary orbits are described. Satellites come in all sorts of shapes and sizes, ranging from half the size of a bus down to something not much bigger than your mobile phone. Indeed if one counts the International Space Station as being a satellite – as we surely must – objects constructed in orbit can be larger still. My intent in this series of blogs is to describe different types of satellite orbit around Earth (geocentric orbits), and the uses to which they are put. It’s all quite simple, and I hope that educators might find the series (and in particular the … Read More

Space War and NZ’s Position - Out of Space

Jan 09, 2019

[avatar user=”duncansteel” size=”thumbnail” align=”right” /] With regard to tracking military satellites newly-launched from eastern Asia and potentially of concern to our allies, New Zealand’s geographical position is of huge (yet overlooked) significance.   Surely no-one could imagine that space-wise there is not a lot going on at present, with another probe just landed on Mars, three other spacecraft missions having encounters with asteroids, and many other announcements showing how our exploration of the solar system is proceeding apace. Exciting times. In future posts I will turn my attention to several of these giant leaps, but immediately there is something more important to discuss and closer to home. In the latter half of 2018 the announcement by the present President of the United States that the nation would be establishing a new service within the US military, a ‘Space Force’, … Read More

It’s crowded at the edge of the solar system   - Out of Space

Jan 01, 2019

[avatar user=”duncansteel” size=”thumbnail” align=”right” /] Looking out at the stars it would be easy to think that the solar system is mostly empty, bar the handful of planets circuiting the Sun and the occasional comet we see passing by. The reality, we now know, is that the edge of the solar system contains a vast population of substantial objects orbiting just beyond Neptune, one of which is currently being visited by NASA’s New Horizons spacecraft.   Sometimes the mechanics of the heavens lead to things happening at inopportune times. I am not talking about astrology. What I mean is that NASA’s New Horizons spacecraft is just flying past a minor planet out beyond the orbits of Neptune and Pluto, and it’s January 1st. That will have played havoc with the seasonal festivities of all involved – heck, … Read More

Numbering our New Years - Out of Space

Dec 31, 2018

[avatar user=”duncansteel” size=”thumbnail” align=”right” /] New Year is coming in a few hours (as I write), at least on the calendar used as the global standard. Not everyone counts years in quite the same way, though.     It takes most of us a week or two to get used to the number of the year having changed. In the days when we still wrote cheques, the first few such slips of paper each year would often carry the signs of hasty corrections in the very last digit at upper right. But imagine what it is like if you also use a different dating system to that which has become the world standard. In my preceding post I wrote about how our common dating system uses a radix defined by the traditional day of the circumcision and naming of … Read More