Out of Space

Satellite imagery of the Nelson bush fire

Duncan Steel • Feb 09, 2019

• bush fires,
• Earth observation,
• natural disasters,
• Nelson,
• remote sensing,
• satellites,
• Tasman District

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 … Read More

Satellite Orbits: Global Navigation Systems

Duncan Steel • Feb 05, 2019

• GNSS,
• GPS,
• navigation,
• Orbits,
• satellites,
• space

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 … Read More

Harry Hindmarsh Atkinson: obituary

Duncan Steel • Jan 27, 2019

• asteroids,
• comets,
• European Space Agency,
• near-Earth objects,
• Nelson,
• New Zealand scientists,
• physics,
• space,
• UK Government

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 … Read More

Satellite Orbits: Global Positioning System

Duncan Steel • Jan 24, 2019

• GPS,
• navigation,
• Orbits,
• Satellite,
• space

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 … Read More

The invention of the geostationary communications satellite

Duncan Steel • Jan 18, 2019

• Arthur C. Clarke,
• communications,
• geostationary orbit,
• history of science,
• Orbits,
• radio,
• rockets,
• satellites,
• space,
• Television

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 … Read More

Satellite Orbits: Geostationary

Duncan Steel • Jan 16, 2019

• broadcasting,
• communications,
• Earth observation,
• geostationary,
• meteorology,
• Orbits,
• satellites,
• space

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 … Read More

Space War and NZ’s Position

Duncan Steel • Jan 09, 2019

• Low Earth orbit,
• military power,
• Orbits,
• radar,
• satellite launches,
• satellites,
• space,
• Space debris,
• space situational awareness,
• Space Wars,
• surveillance,
• tracking space objects

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 … Read More

It’s crowded at the edge of the solar system  

Duncan Steel • Jan 01, 2019

• asteroids,
• astronomy,
• comets,
• Minor Planets,
• planetary science,
• planets,
• science communication,
• solar system,
• space exploration,
• Space Science,
• Spacecraft

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 … Read More

Numbering our New Years

Duncan Steel • Dec 31, 2018

• astronomy,
• Calendars,
• Christmas,
• Equinoxes,
• History,
• New Year,
• religion,
• science communication,
• Solstices

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 … Read More

And so this is Christmas…

Duncan Steel • Dec 19, 2018

• astronomy,
• Calendars,
• Christianity,
• Christmas,
• Equinox,
• History,
• New Year,
• religion,
• science communication,
• solstice

The date of Christmas is a matter many find confusing, and yet the adopted anniversary is easy to understand if you follow through the history, astronomy and human biology that are involved.  Why is the Nativity commemorated on December 25th, when it is clear Jesus was not actually born on that date? And how can a year be termed “Before … Read More