Stars in the city: an introduction to urban astrophotography

As a twelve year old astronomy nut, I was lucky enough to receive a small refracting telescope. Almost immediately, I utilised scrap timber to build an observatory in my back garden, just about large enough for two children (plus star charts, a moon map and at least as important in my opinion, a flask of hot chocolate). I recall it even had a sliding roof, thanks to a pair of dismantled wardrobe doors.

Although the imaging wasn't too bad - I lived in a small town, so light pollution was relatively low - I soon discovered that good optics are only part of the story: without a proper mount, a telescope can be next to useless. In this particular case, I obviously hadn't read the brief introduction to mounts in my trusty The Observer's Book of Astronomy by Patrick Moore. At any rate, I clearly didn't understand the difference between proper equatorial or alt-azimuth mounts and the piece of junk that allowed my refractor to sit on a table top. Therefore, except for getting to know the lunar landscape, I saw little that I couldn't more easily view with my 20x50 binoculars.

Jump forward thirty or so years and courtesy of a large tax refund I found myself in possession of a small reflector, complete with equatorial mount and right ascension motor. After some months getting to know it I started buying accessories, aiming to learn the ins and outs of astrophotography. Thanks to numerous websites I picked up some useful techniques and excellent free software - and as importantly, how to use the assemblage - and now feel it's about time I offered a one-stop-shop guide to getting the best images on a low budget in your own backyard. Of course there are plenty of books available, but most are at least one to two hundred pages long and often specify expensive kit, so this post is an attempt to cover the gap for those wanting an astrophotography 101 with the absolute minimum of basic equipment. Of course, it's entirely my approach, so there are no doubt plenty of other tutorials out there. But at least mine's short!

1. Equipment

I have to admit that I order all my kit from overseas, since New Zealand has few astronomy retailers and those there are appear to have a fairly limited range, often at uncompetitive prices. However, it is possible to accumulate a decent beginner's assortment for around a NZ$1000 / £500. I would always recommend a reflector as a first telescope, being far cheaper than a refractor with similar capability. The Newtonian is the most common, least expensive and easiest to maintain type of reflector, mine being a Sky-Watcher 130. As per the name, the primary mirror is 130mm (about five and a half inches in old money), which is really the minimum useful size for a reflector.

The telescope came with a red dot finder scope, several okay-ish eyepieces, a right ascension motor drive, a poor 2x Barlows and a reasonably stable equatorial mount. Since then I've bought a planetary camera, a good quality 2.5x Barlows, a compact camera adaptor, an adjustable polarising filter and a collimating eyepiece*. I've also made my own Bahtinov mask, courtesy of a website that supplies patterns for various diameter/focal length combinations. Although 'go-to' mounts are available, I agree with the general consensus that the best way to learn the night sky is by manually pointing the telescope, not just programming a target and letting the telescope slew into position for you.

*For complete newbies, a Barlows is a cheap method for increasing magnification with only a limited number of eyepieces, fitting into the eyepiece holder below the eyepiece. A collimator is used to check and correct misalignment between the primary and secondary mirrors, whilst a Bahtinov mask is a simple focussing aid.

I'm lucky to live in the 'winterless north' of New Zealand, but for those in colder climates it's probably wise to make or purchase a dew cap, or rather one for the main tube and another for the finder scope. A rubber eyecup for the eyepiece might also be a good idea; there's not much point in trying to observe anything if water is condensing on the mirrors or lenses.

I would recommend a CCD or CMOS telescope camera or modified webcam, since they are a lot cheaper than a digital SLR and far lighter. The EQ2 mount supplied with the Sky-Watcher needs adjusting on both axis depending on the combination of items in the eyepiece holder, otherwise at high angles it has a tendency to droop. The EQ2 counterweight can just about handle the long tube: experiments with a compact digital camera in a purpose-built mount have confirmed that additional off-centre mass requires regular fine-tuning to retain balance. Incidentally, I use a colour planetary camera since I tend to have short sessions - around two hours - and so only want to film each pass once rather than repeating in triplicate for colour filters, even if mono cameras achieve better resolution.

2. Where to observe?

Of course this is the least flexible part of astrophotography, since you are restricted by the buildings and trees in your garden - or any other convenient location. Not only is your view of the night sky limited by physical obstructions but pollution can severely impact viewing. As I have discussed previously, light pollution is the most obvious form, with street lighting often worse than that of buildings. I've found that even as low as ten percent cloud cover can degrade astrophotography, due to the artificial light reflecting off the clouds.

Heat pollution may be less obvious but can also severely reduce image quality. Therefore, try to avoid pointing the telescope directly above nearby rooftops or you will be looking through a rising column of hot air, either the radiating heat from earlier that day or leaking from poorly-insulated buildings that are heated at night. Also, never set the telescope up indoors and point it through an open window: the thermal variations will generate shimmering galore. Wind above the lightest of breezes cannot be recommended either, not just for 'scope instability but also because dust and particulates can deteriorate the viewing. High water vapour content is bad for the same reason; here in humid Auckland I'm frustrated by the hours before and after rain, meaning the best seeing I've ever had has been in high summer after a rain-free week.

Before using a reflecting telescope, it needs to be set up outdoors well in advance of the viewing session in order to allow the mirror to cool down to the ambient temperature. The cooling time is directly proportional to the primary mirror diameter, which for my 130mm is usually about one hour.

3. What to photograph?

For urban astrophotography I've found the moon and planets to be by far the best targets. By planets I mean just Mars, Jupiter and Saturn. Venus may be both large and bright but due to its cloud cover will never present anything other than a featureless crescent or globe.

The moon is endlessly fascinating, best observed between new moon and first or last quarter (i.e. half full). During these periods, the low-angle sunlight generates shadows that model the features without being overly bright. When observing closer to full moon I always use a polarising filter to reduce the incredibly intense light, but since sunlight is then perpendicular there is little modelling to give relief to the geology.

Jupiter is by far the best planetary target for small telescopes; in addition to the cloud patterns you can see some or all of its four largest moons (Ganymede, Callisto, Europa and Io), their number and position changing on a nightly basis. Saturn is an excellent target too, the angle of the rings varying widely. I've also found Mars to be surprisingly worthwhile even when not at its closest to Earth, with the major features clearly visible in reasonable seeing conditions.

The problem with deep sky objects in urban astronomy is that they are both difficult to locate and their light is easily degraded by light pollution and particulates. I've attempted to get images of more familiar DSOs such as the Orion Nebula with several cameras, but the results are hopeless.

Once you have some experience under your belt, you may want to attempt photographing the International Space Station. Various websites list details for near-future visible passes over any location, when it is easy to spot due to being obviously brighter than any other man-made orbiting object. However, since the ISS will only be visible for around four minutes each pass you have to quickly manoeuver the telescope whilst keeping it in an area that is only about thirty arc seconds in diameter. If I manage to get any image at all, it is usually a few dozen frames resembling an out of focus capital 'H', so it's definitely a target for those with a lot of patience - and good hand-eye co-ordination.

4. Locating targets

Although I'm against beginners using go-to mounts, there are various planetarium programs and mobile apps that are extremely convenient for locating target objects. I use Stellarium, excellent freeware that can be set to any location on Earth and has a night time (i.e. red on black) mode to help keep your eyes sensitive to the dark.

Northern Hemisphere observers are at an advantage compared to their counterparts south of the equator due to the ease with which the North Celestial Pole can be found. Not only is Sigma Octantis slightly further from the SCP than Polaris is from the NCP, it is considerably dimmer. Therefore I've always had great difficulty in lining up the telescope to the South Celestial Pole for setting circles with the polar axis motor drive. There are telescope-camera combinations that allow use of auto guiding software but I prefer the manual approach to finding your way around the night sky. Besides which, spotting the closer planets is pretty easy, the most common potential mix-up being Mars with the red star Antares (whose name after all means 'equal to Mars')! All in all, manually slewing the telescope using a printed or online star chart as a guide is the best way to learn.

5. Harvesting ancient light

I tend to take 20-60 seconds of video or still sequences when imaging the moon and planets, depending on various factors such as target brightness and seeing conditions. Planetary cameras allow some manual adjustments such as exposure length and gain, with shorter exposure lengths usually better so as to minimise degradation within a single image. When the seeing is reasonable I stack the planetary camera on top of the 2.5x Barlows, which gives a decent angular size for the planets. I've also used a compact CCD camera with an eyepiece and Barlows combination, but the camera adaptor is fiddly to align on three axis with the eyepiece and the extra weight can mean regular adjustments to the mount, depending on telescope angle.

6. Image processing

Once you have the raw video or sequence of stills there is a lot that can be done to improve the image quality, initially by aligning and stacking the best individual frames and discarding the rest. Again, there is a lot of freeware available to help with this. I use RegiStax, often creating 3 or 4 permutations from each sequence and then loading the best one in Photoshop for final tweaks. (If you cannot afford the latter, then GIMP - GNU Image Manipulation Program - is a great freeware alternative.) It can take a while to understand how to use the likes of RegiStax, but there are YouTube tutorials covering various processes and I always consider a trial and error approach to be a good way to learn!

So what sort of results can you expect from all this effort? The biggest factor in quality is undoubtedly the seeing conditions, which are outside of your control. However, just occasionally you get a perfect night. I find that it can take a few sessions to generate a half-decent image, so it definitely takes perseverance.  Since a picture is worth a thousand words, you can judge the results for yourself here.

Have spacecraft, will travel: planning the first manned Mars mission

As a space travel enthusiast since I was knee-high to a grasshopper it took me many years to appreciate robot probe missions with anything like the zeal engendered by manned spaceflight. As a schoolboy I watched the first space shuttle mission launch in 1981; no doubt like a multitude of others I initially considered this the start of the ‘casual' rather than pioneering phase of astronautics. Therefore it wasn't long before I asked myself the obvious question: when will there be a crewed mission to Mars?

Mars seems extremely familiar, no doubt due to the myriad of science fiction novels and films concerning the Red Planet. The last decade has seen a proliferation of news stories as various orbiters and rovers gather enormous amounts of - at times puzzling - data. However, none of the numerous projects of all scales that have investigated a manned mission have ever lifted off the launch pad. So here's a brief look at the state of play, not to say of course that this might not look woefully dated within the next few years.

1) Who will go to Mars?

Obviously the USA will supply the most funding so they will run the show. Or will they? The NASA budget available for planetary science is less than half that for International Space Station (ISS) operations, although of course the former are all unmanned missions. In fact, the Planetary Society has claimed that NASA spends less each year on interplanetary probes than the USA does on dog toys! A manned mission would have to negate this trend, as realistic estimates could be around US$500 billion for a single mission.

President Obama's announced half-billion dollar increase to the NASA budget is unlikely to be replicated by any Tea Party candidate who might (God forbid) achieve power. Unless that is we see a return to Cold War rivalries, with China offering a two-horse race to Mars. That might sound unlikely, but in 2006 the Chinese Government announced a long-term goal to land a crew there between 2040 and 2060. Since the US refused to allow them ISS involvement due to not wanting its technology to become available to Beijing, it is doubtful the Whitehouse would be any happier to cooperate in a Mars mission.

Either way, it's probable that some of the ISS partners would collaborate. However unrealistic it now appears in light of the financial crisis, back in 2001 the European Space Agency (ESA) announced its own plan for a crewed Mars landing in the 2030s. There was even a suggestion to include Russia as a minority partner, but the political situation there may prove prohibitive.

It doesn't just have to be other Western nations who participate in a NASA-led project, as numerous private companies are now involved in the commercial space programme. No doubt collaboration between some of the long-established aerospace giants and recent start-ups such as Space-X - whose long-term goal is to establish a Martian colony - with various Western governments would be more palatable to finance ministers. But it's still early days for the private sector: smaller infrastructure may shorten timescales compared to monolithic state enterprise, but as the Virgin Galactic SpaceshipTwo crash shows, developing even sub-orbital craft at this level still carries enormous risk.

So all in all, it could be the US and ESA, with or without substantial private investment, or China in a race with a Western bloc or (as an extreme longshot) Dutch engineer and entrepreneur Bas Lansdorp, whose Mars One mission plans to regularly send crews of four non-professional astronauts on a one-way trip to the Red Planet from 2025. So far he has raised about 1/8000th of the project's already shoestring budget, but that hasn't stopped thousands of would-be colonists from applying. In addition to the necessary privations, these volunteers would also be the subjects of a fund-raising reality television show. If doesn't sound even vaguely like the product of an insane society then I don't know what is. Perhaps we should just turn our backs on the rest of the universe and just spend our lives uploading selfies to social media sites?

2) What will happen?

In theory it sounds simple: a small group of professional astronauts with various scientific backgrounds will spend up to two years on a high-risk mission, exploring the Martian surface for perhaps a month or so, then bring back copious samples of rock, soil, atmosphere and ice for more detailed examination on Earth.

The BBC ‘s 2004 mockumentary Space Odyssey: Voyage to the Planets showed the deadly effects that ionizing radiation can have on interplanetary travellers. The Mars Science Laboratory, carrier of the Curiosity rover, spent the Earth to Mars transit recording the radiation levels. It confirmed that they were high enough to risk crew members contracting various serious conditions such as cataracts and cancer. Incidentally, female astronauts would apparently be more prone to radiation-induced cancers than male colleagues. A 2012 mission plan considered developing an electromagnetic anti-radiation shield, but most designs are looking to use traditional aluminium construction, perhaps with polyethylene shielding around the pressurised cabins. This definitely appears to be a case of fingers crossed as much as relying on advanced materials science.

The long duration spent in shipboard micro-gravity will also cause physical problems such as bone and muscle deterioration. The astronauts/cosmonauts/taikonauts (delete as preferred) will then have to adjust on Mars arrival to the one-third Earth gravity. As well as avoiding radiation on the Martian surface they will have to minimise contamination from the fine dust: minute particles suspended in the atmosphere could cause lung and thyroid problems if allowed into the lander cabin.

Besides the physical problems, the pioneering crew will also have to contend with the psychological effects of having travelled further from the Earth than any other humans - by an enormous margin. It's one thing to undertake a mission on the ISS - with a regular exchange of crew and a close-up view of the Earth via the cupola - but quite another to spend several years away from fresh air, blue skies, and all the other fantastic things we take for granted. The interplanetary distances would of course be exacerbated by the lack of real-time conversation: the one-way journey time for radio signals from the Martian surface is between four and twelve minutes.

There has been much research into astronaut's disturbed sleep patterns, which can obviously have deleterious effects on their work as well as their mental health. The claustrophobic conditions may contribute too: negative emotions blighted the small group of inhabitants of the Arizona-based Biosphere 2 sealed ecosystem in the 1990s. In addition, this experiment had distinct problems maintaining the environment, with a primary issue being the fluctuating oxygen and carbon dioxide levels. All in all, there are likely to be problems even the best planned mission won't have predicted.

3) When will it take place?

By comparison to low Earth orbit missions, a trip to Mars would be several magnitudes greater. If you want a pioneering aviation analogy I've just figured out that ratio of the Earth-Moon distance compared to the mean Earth-Mars distance is akin to the Wright Brothers' first flight of 36.5 metres being followed up by another spanning over 5 kilometres!

I can foresee two main issues to consider when planning mission timelines, which should ideally coincide to suggest an ideal launch window. The first is the relative orbital mechanics of the two bodies, which can be exploited so as to utilise a minimum fuel trajectory. The second relies on the eleven-year solar cycle: maximal solar activity helps to block interstellar cosmic rays and so reduce the risk of radiation poisoning. Although the sun's output would be at its peak, the astronauts would be safe from solar flares and coronal mass ejections providing they didn't need to undertake any spacewalks or surface EVAs for their duration.

There are several research projects that if one were to prove successful, could reduce by several decades the time before humanity is ready for its first manned Mars flight. The University of Washington and Lockheed Martin are both working on nuclear fusion technology suitable for such a mission. By reducing the journey time from between six and eight months to just three months there would be far less health risk to the crew, as well as presumably considerable weight savings on air and consumables.

Therefore it may become feasible as early as the 2040s but I doubt any earlier, regardless of how much advance is made in fusion technology. On top of all the usual political and socio-economic fluctuations there are just too many important longer-term issues that need resolution here first.

4) Where will it take place?

Mars, of course! The planet has a wide variety of locales (hint of travel brochure there), some rather more interesting than others. If the public get to vote on sites for exploration - bearing in mind that taxpayers will no doubt be funding the majority of the mission - conspiracy theorists and assorted nutbars might promote the curious tetrahedrons (note, not pyramids) of Elysium. Presumably they're enormous ventifacts, but they still appear to be very interesting geological features.

Then there's the great canyon system of Valles Marineris, over 4000 kilometres long and up to 7 kilometres deep. Or how about the 25 kilometre high Olympus Mons and its surrounding escarpment? In Pale Blue Dot: A Vision of the Human Future in Space, Carl Sagan suggested that it might be fruitful to explore the slopes of the Martian volcanoes in case they are scattered with diamonds ejected from the carbon-rich mantle!

Other locations that are just begging for detailed exploration are the polar caps, now thought to be mostly composed of water ice rather than frozen carbon dioxide, and caves or caverns, which would not only be a good place to search for native microbes but also to hide from radiation or dust storms.

5) Why will it happen?

This is perhaps the most difficult question to answer. Carl Sagan argued that the mission would fulfil the deep-seated need for exploration that our species - only recently converted from a nomadic existence - still feels. There is something to be said of this provision of a surrogate for human wanderlust, as identified in Bertrand Russell's 1959 quote: "a world without war need not be a world without adventurous and hazardous glory." This form of argument seems fairly mainstream in astronautic circles: even NASA's budget estimate for 2016 includes the phrases ‘reveal the unknown' (very likely) and ‘benefit all humankind' (which seems rather less obvious, except for Earth resources and weather satellites).

Against this notion are rather more pragmatic motives such as a combination of accelerated technological development and national prestige. But if nuclear fusion power is acquired in time for the first mission it's difficult to see what else will be gained from spending say half a trillion US dollars on a single crewed flight: wouldn't it be wiser to spend such vast sums on environmental stabilisation or medical research here on Earth? I've already commented on the potential white elephant of the ISS and there are no doubt many who don't consider any manned space exploration a suitable use of such enormous resources.

It's obvious that there are distinctive practical advantages to having humans on the spot rather than relying on robots. One issue that a single manned mission might be able to resolve that countless probes wouldn't is the question of life on Mars. The haze and plume seen in 2012 and the seasonal methane suggest some very interesting meteorological phenomenon if there isn't a biological explanation, but if there is any Martian bacteria then surely the mission could be deemed worthy of its immense budget? Somehow, I have my doubts…

One day in the next few centuries there could well be - unfortunately - branches of Starbucks and McDonalds on Mars and the Red Planet will be an alien frontier no more. But until then, any humans who undertake such an incredible journey will be pioneers in the Yuri Gagarin/Roald Amundsen/Edmund Hillary mould. However, I doubt the first human to step onto the Martian surface will use the latter's keen Kiwi phraseology: "we knocked the b***d off!"

Warp engines offline, Captain: has science fiction become confused with science fact?

The current bickering in Copenhagen seemingly ignores a rather pertinent issue: our skills and experience in reversing climate change are almost exactly zero. Of course we can drastically cut back on fossil fuels, increase energy efficiency and possibly even slow down population growth, but there is little on the technological horizon that can profoundly alter the climate in favour of our species. Yet the implicit view seems to be that if a political solution is found then a practical solution will follow in due course.

So why is it assumed that given enough Government funding, the people in white lab coats can perform miracles of climate engineering? This attitude is symptomatic of an ever-widening gap between the scientific forefront and public perception. Many strands of contemporary science are so detached from everyday life that they inhibit straightforward public assimilation, whilst the ubiquity of electronic consumer goods may be lulling us into a false sense of security regarding our abilities. We are surrounded by 'space age' gadgets and technology from Wii to Wi-Fi that only a generation ago were strictly for James Bond. And with Virgin Galactic seemingly about to usher in a new age of space tourism, becoming an astronaut will be akin to a very expensive form of air travel, though a sub-orbital hop hardly counts as boldly going anywhere.

Another possible cause that doesn't seem to have gained much notice is the influence of science fiction films and television series. With their largely computer-generated visual effects, most Hollywood product effortlessly outshines any real life counterpart. For example, doesn't the International Space Station (ISS) resemble nothing so much as a bunch of tin cans linked by Meccano struts? Yet the ISS is about as good as ultra-expensive high-technology gets, being by far the largest man-made structure ever assembled in orbit. Given a choice between watching ISS crew videos (Thanksgiving dinner with dehydrated turkey, anyone?) and the likes of Bruce Willis saving mankind from doomsday asteroids, most people unmistakably opt for the latter.

Now that the majority of humans live in crowded conurbations far removed from our ancestral peripatetic existence, the desperation for new horizons is obvious. Yet our exploratory avatars such as the Mars rovers hardly qualify as charismatic heroes, hence the great appeal of fictional final frontiers. The complex interplay between reality and fiction is further confused by the new genre of "the science behind…" book. Frequently written by practicing scientists for the likes of Star Trek, The X-Files, Dr Who, etal, the blurring of boundaries can be exemplified by one buyer of The Physics of Star Trek who compared it to A Brief History of Time (although admittedly Stephen Hawking did write the foreword to the former).

Furthermore, the designers of such disparate items as medical monitoring equipment, flip top phones and military aircraft instrumentation have been inspired by Hollywood originals to such an extent that feedback loops now exist, with arcade simulators inspiring real hardware which in turn inspire new games. Articles discussing quantum entanglement experiments seem obliged to draw a comparison with the Star Trek matter transporter, though the transportees are as yet only photons. Theoretical physicist Miguel Alcubierre has even spent time exploring the fundamentals for a faster-than-light 'warp' drive, although it's unlikely to get beyond calculations for some little while. Blue-sky thinking is all very well, but there are plenty of more pressing issues that our finest minds could be working on...

Closer to home, it appears that a lot of the hype surrounding sustainable development is just that. Are we simply in thrall to companies hoping to make a fast buck out of fear, flogging us technologies about as useful as a chocolate teapot? A recent report suggested that the typical British home would gain only minute amounts of electricity from installing solar panels and wind turbines, although the development of spray-on solar cells may drastically improve efficiency in the next few years. But where does this leave us now? Although our species has endured sudden, severe climate changes such as the end of the last glaciation ten thousand years ago, current population density and infrastructure forbid anything as simple as packing our things and moving to higher ground. Cutting back on fossil fuel consumption is clearly necessary, but isn't it equally as important to instigate long-term research programmes in case some of the triggers are due to natural causes such as the Milankovitch cycles? If global temperature increase is inevitable, never mind potential cooling in Western Europe due to a diverted Gulf Stream, then reducing greenhouse gas emissions is merely the tip of the iceberg (sorry, couldn't resist that one).

Anyone who looks back at the grandiose pipe dreams of the 1960's can see that our technological ambitions have profoundly reduced in scope since their idealistic heyday; what we have gained in the micro-scale technologies, we have lost in the giant engineering projects envisaged by likes of Gerard O'Neill, Freeman Dyson, and Arthur C. Clarke. Yet Thunderbirds-style macho engineering is presumably the type we will need to develop if we are heading for a chain reaction of environmental change.

Restructuring an ailing climate will take more than a few decades of recycling and installation of low-voltage light bulbs - we will have to mobilise people and funds on a unique scale if we are not to prove powerless against the mighty engine of Planet Earth. To this end we need to spread the message of our own insignificance, mitigated by research into alleviating the worst-case scenarios: there can be no Hollywood-style quick-fixes to the immense forces ranged against us. No-one could argue that even short-term weather forecasting is an exact science, so discovering whatever trouble the Quantum Weather Butterfly has in store for us will keep earth scientists engaged for many years to come (and there I go again, confusing fiction with reality, doh!)