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.

Big Eye Wide, But Shut - Out of Space

Nov 23, 2020

A few days ago the US National Science Foundation (NSF) announced the decommissioning of the Arecibo Observatory in Puerto Rico. This story has been the subject of items in the mass media around the globe, and also in New Zealand. Cables supporting the massive horns and radio receivers above the dish have snapped, the actual dish surface has been badly damaged, and following more than half-a-century of intensive use it has been decided that it would be too costly and dangerous to try to fix the telescope. Many astronomers and space scientists have been stunned by this decision. (There are numerous other reports on space-related websites, such as here and here, and here, and here, and here; and you might also be interested to follow this Twitter feed: #whatarecibomeanstome .) Most of … Read More

Water on the Moon? - Out of Space

Oct 27, 2020

The space news this week is largely focused on an announcement from NASA regarding the discovery of water on the Moon. Not liquid water – the lunar surface is far too cold for that – but apparently ice deposits in the surface layers in near-polar regions, and perhaps deeper below the surface too. Finding water on the Moon in an accessible form would be important for our future exploration and exploitation of Earth’s natural satellite, perhaps involving permanently-crewed scientific outposts. The water itself would be essential for drinking, washing, and growing food; it could be electrically separated to produce oxygen for breathing; and when split into its constituent hydrogen and oxygen it could be used as rocket fuel. Transporting the necessary water from Earth would be hugely expensive, because we are in a gravity well, whereas the gravity of the … Read More

Science at the movies: The new comet impact film - Out of Space

Oct 22, 2020

Disaster movies forever capture the public attention… but did you ever stop to think that the word disaster actually means bad star? That is, ‘dis’ implies a pejorative (as in disease, or disgust, or disrespect), while ‘aster’ comes from the Latin astrum, similarly the Greek astron. Obviously enough, this derives from old astrological beliefs. In modern science, asteroids are called that because they are star-like (points of light in a telescope), while comets get their name from an ancient Greek word meaning hair-like, referring to the tails exhibited as they cross the night sky. The archetypal disaster movie really should involve an asteroid or comet striking the Earth, then, and there has been no shortage of them. To list a few: Meteor (1979), starring Sean Connery and Natalie Wood (note the pun: starring) Armageddon (1998), and modesty prohibits me … Read More

Possible inter-satellite collision on Friday - Out of Space

Oct 14, 2020

Two objects in low-Earth orbit may collide with each other on Friday, in a hyper-velocity impact which would lead to millions of fragments being left on-orbit, each potentially-lethal to functioning satellites. Fingers crossed (not that I am superstitious) that it is a miss, rather than a hit. One local media article is available here. Above I wrote ‘objects’ because neither is an operational satellite. One is Cosmos-2004, a Russian military navigation satellite launched in February 1989, and long past its use-by date. It circles our planet at altitudes between 977 and 1020 km, rather higher than most satellites in so-called low-Earth orbit (LEO); for example, the International Space Station (ISS) orbits at an altitude just above 400 km. If we deserted the ISS, within a few years/a decade or so the tenuous atmospheric drag at that height would cause … Read More

Small asteroid to make near-miss of Earth in NZ skies tonight - Out of Space

Sep 24, 2020

Sorry for the late notice on this one, but I only just heard myself, in common with most of the human race. A small asteroid, somewhere between the size of a truck and the size of a house in dimensions, will hurtle past the Earth tonight, dipping closer to our planet’s surface than the altitude at which TV transmission and weather satellites orbit high above the equator. Not only that, but it seems that it will pass across the sky above New Zealand and Australia, meaning that astronomers here could get the best view during its closest approach, at about 11:18pm NZST. At that time the asteroid would be visible in the constellation Pisces, fairly close to Mars in the sky (the bright reddish object that will rise in the east at about 8:15pm), but actually very close to the … Read More

Tiny asteroid whizzing past Earth today - Out of Space

Jul 28, 2020

Four weeks ago I wrote about the last time a sizable asteroid hit our planet – the ‘Tunguska Event’ of 1908, when an object about 50 metres across exploded above the Siberian taiga – but smaller cosmic rocks shoot close by Earth fairly frequently. In the past 42 hours (as I write) a tiny asteroid less than five metres in size has been discovered by astronomers in Arizona, tracked from Mt John Observatory in New Zealand, and then additionally followed by observers in Croatia and France. As a result we know it will miss us, but will today fly by at a distance that is less than the altitude of geostationary satellites. This asteroid is called 2020 OY4. The ‘2020’, obviously-enough, is the year of discovery. The ‘O’ denotes the half-month of discovery (the second half of July): we … Read More

The day the sky fell in - Out of Space

Jun 30, 2020

It’s June 30th, marked as Asteroid Day by many people of an astronomical bent around the globe. On this date in 1908, early in the morning in a remote part of central Siberia, the sky fell in. Well, not literally. What happened is a substantially-sized bit of cosmic detritus – a lump of rock and perhaps ice – arrived in the upper atmosphere at a speed of around 30 kilometres per second (108,000 kph). It was about 50 metres in size, based on a stone-like density and an energy release that has been estimated as being between 3 and 20 megatonnes of TNT equivalent. Compare that with the Hiroshima nuclear bomb, at 15 kilotonnes about a thousand times less energetic. This was some big bang. This occurrence is generally known as the Tunguska Event (for the Podkamennaya Tunguska … Read More

The fate of the albatross - Out of Space

Jun 19, 2020

Yesterday I wrote that I can find some reason to celebrate almost any date, and today (19th June) is no exception: it’s World Albatross Day. Unfortunately the day began with a news story concerning a commercial fishing boat killing four endangered Antipodean albatrosses off NZ’s East Cape. Even more unfortunately, such events are not unusual, with several others media stories this year concerning the loss of albatrosses and other seabirds as a consequence of commercial fishing (for example, see here, and here, and here). Clearly there are reasons for concern. In my post yesterday about Wellington and Nelson I wrote that there was not much about astronomy or space (my usual subjects) involved. In the present blog post there is, in fact, a bit of an astronomy connection, and I will come to … Read More

Connecting Wellington and Nelson - Out of Space

Jun 18, 2020

My blog post here has essentially nothing to do with space and astronomy, my usual subjects, but it concerns a little matter of history I thought I’d like to write about. Once upon a time I wrote a long book about calendars, and as a consequence accumulated knowledge about many of the special dates in the year which could be used as an excuse for having a beer. Two days ago it was Bloomsday, a good reason for a Guinness (and also for giving flowers to someone: my doctor’s surgery staff kindly obliged me by accepting a bunch of yellow roses). Although the hours are running out, today is June 18th, and so the 205th anniversary of the Battle of Waterloo. I imagine that many today know about it mainly from the song by ABBA, but the battle … Read More

Where is New Zealand’s highest point? - Out of Space

May 01, 2020

Did you know that the top of Mount Cook is by no means New Zealand’s furthest point from the centre of the Earth? And that Samoa’s tallest mountain is seven kilometres further from our planet’s core than anywhere in NZ? The highest point anywhere, in terms of separation from Earth’s centre? — It’s not Mount Everest.  It’s the sort of question that gets asked as a tie-breaker in a pub quiz: I am stood on the point on Earth’s surface that is furthest from its centre. My feet are two-feet apart (of course) along a north-south line. Which country is each foot in?  Cue for head-scratching and debate. Most people think that the point in question is the top of Mount Everest, and some know the border between Nepal and Tibet (as claimed by China) goes through that peak. In consequence … Read More