Category Archives: Science

Fermentation

Last week’s blog post, all about alcohol and law, triggered a number of interesting discussions, and one of them (from a Goodreads friend) has inspired this post. It all started with my brief comment about the prospects of brewing on the ISS, up in the microgravity of low earth orbit. But before we get into space, let’s think about what happens during fermentation. (I’m going to mostly focus on beer in this post but similar comments could probably be made about wine).

Beer making in the Egyptian 6th dynasty (British Museum)
Beer making in the Egyptian 6th dynasty (British Museum)

People have been brewing beer for many thousands of years – in Egypt the process was well-organised long before 2000BC, and the earliest confirmed evidence for beer-making that I am aware of is from the 5th millennium BC, at Godan Tepe in modern Iran. I strongly suspect the history is much longer, and that more evidence will turn up in time.

Pottery beer jar, Egypt, c. 1600BC (British Museum)
Pottery beer jar, Egypt, c. 1600BC (British Museum)

Beer making has been credited with all kinds of benefits to humanity, including driving an early wave of technological development. Quite apart from the enjoyment factor. Back then, and for a great many years subsequently, beer was made in open fermentation vessels – basically very large pottery containers, semi-porous and so holding on to residues of yeast and the like. It was often a spin-off of the bread-making industry, seeing as how you needed yeasts and grains for both. Both bread- and beer-making have had, at times, vaguely magical or alchemical associations – these very ordinary foodstuffs are hidden away in a very ordinary vessel, and over the course of a few days they transform into something quite extraordinary. In early times, hops were not added (this seems to have been introduced in the middle ages), but people did sometimes add other flavourings such as fruit or spice extracts.

A 16th century brewery (Wiki)
A 16th century brewery (Wiki)

Now, during fermentation the yeasts work with the various sugars in the raw mixture, together with oxygen in the air at the top surface, and convert these into alcohol and CO2. The process is self-limiting – yeasts eventually kill themselves in too high a proportion of alcohol, so fermentation slows and stops. A brewer can choose whether to let the process go on to completion, or stop it early. An early finish means lower abv (alcohol by volume… the strength of the brew) and a sweeter drink. In olden days, I suspect brewers had conventions about how many days to leave the mixture – nowadays brewers have a more mathematical set of targets to do with final abv balanced against taste. Also, large breweries are very interested in keeping consecutive batches consistent about strength and flavour, whereas a domestic brewer, or someone in pre-industrial days, was less bothered about this.

Finally, carbonation. If you are brewing in an open-top vessel, all the CO2 generated simply goes out into the air. And if you are brewing at room temperature, especially in a hot climate like Egypt, not much gas is held in the liquid anyway. Nowadays we brew and store beer at specific temperatures in order to achieve a target level of carbonation. The colder the beer, the more gas it can retain, and then release as the drinker opens it up at room temperature. You brew for the preferences of your target market – lots of fizz (as in many lagers) or hardly any (as in many real ales).

Fermentation vessels - Grasmere
Fermentation vessels – Grasmere

That brings us onto the specific issue that triggered these fine discussions. What happens in low gravity? Not a problem in ancient Egypt, but looking ahead it’s an issue we will want to solve. Consider a modern fermentation vessel – a cylinder, usually with a cone at the base, and considerably taller than a person. As yeast ferments here on earth, different groups of yeasts arrange themselves at different levels in the vessel – some near the top and others near the bottom. This reflects slightly different ways in which they turn the sugars into alcohol… the sugar level varies in a gradient as you go up and down the vessel. As the yeast becomes exhausted, and starts to die because of the alcohol percentage, the yeast particles sink into the cone, taking with them some of the other residues like hops, grain particles and so on. The beer slowly clarifies by itself, though most brewers also use specific methods to end up with a clear rather than cloudy beer.

The ISS in low earth orbit (NASA/JPL)
The ISS in low earth orbit (NASA/JPL)

That’s fine here on Earth… but in orbit several problems arise. First, there is no real sense of up and down. So a yeast that is used to being near the top of a vessel, with its preferred environment of sugars and whatever, does not know where to go. Likewise, as they finish their job and die from overindulgence in alcohol, there is no “down” direction into which they can settle. Finally, there’s no particular reason why the liquid would stay in one clump – you could easily end up with several disjoint blobs of liquid, with varying proportions of the yeast you had added, each fermenting to different extents.

Centrifugal Fermenter (speculative!)
Centrifugal Fermenter (speculative!)

So this was the point I got to in my Goodreads discussion, which triggered several follow-up chats here in Grasmere. Not that we’re (yet) planing on an orbital version of our various beers and ales, but it is good to be ready for the future! The best answer we could come up with was to artificially introduce a sense of up and down by means of a kind of slow-speed centrifuge. Not so fast as to drive all the solid matter to the outside too quickly, seeing as you need it spread through the liquid at first, but fast enough that the liquid stays in one body, and the yeast can tell which tell which way is up and down. (As a side issue, you’d probably want two of these, rotating in opposite directions, so as not to off-balance the space station itself).

The fermentation will generate CO2, and you don’t want to just dump that into the cabin air supply, so you capture that with a safety valve coming out along the spindle (the “top” of the vessel). That can then either be kept for later use – as many breweries fixed here on Earth do, so as to reuse a resource which costs real money – or fed slowly back into whatever air-purification system takes your fancy. When the time comes to clarify your beer, you just spin the centrifuge faster and let the solid particles accumulate in the “bottom”, taking the splendidly clear beverage out of the “top”.

Artwork, astronaut drinking on the moon (WallpapersByte)
Artwork, astronaut drinking on the moon (WallpapersByte)

Bottling would be an interesting task, since yet again it is something that here on Earth relies on gravity as well as some back-pressure to get the liquid where you want it to go. But if you’ve successfully got this far, I’m sure that the final stage of getting your finished beer into some kind of container would not be an insuperable problem. In orbit you want low carbonation anyway – the last thing you want is for some rogue container to fob frothy mix all around the interior of your capsule. So you keep the whole thing chilled, to hold the gas in suspension in the liquid, and in any case you aim for a quiet liquid rather than a lively one! And voila – you have Orbital Beer, and happy astronauts…

As mentioned very briefly in Far from the Spaceports, concerning the legendary Frag Rockers bar,

“You’ll need to go to Frag Rockers to get anything decent. Regular fermentation goes weird in low gravity. But Glyndwr has got some method for doing it right. He won’t tell anyone what.”

For the curious, here is a British Museum video of recreating an ancient beer-making process based on what we know of ancient Egypt…

 

Laws, qualifications, and the drinking of alcohol

University of Cumbria at Barrow - where I took the course
University of Cumbria at Barrow – where I took the course

I heard today that I had passed the study element of a Personal Alcohol Licence, which (after I have gone through a police background check and a few other formalities) allows me to authorise the sale of alcohol in England and Wales. Not in Scotland, Northern Ireland, or indeed anywhere else in the world, but I guess you have to start somewhere.

Now, this is far from my most advanced academic qualification, but the intriguing thing about this one is that it legally entitles me to supervise – and therefore take legal responsibility for – the public sale of what is undoubtedly a kind of drug. Without the licence, I can work under someone else’s supervision, but cannot just set up and flog booze on my own account. With it, and subject to a bunch of other constraints, I can do just that.

You can imagine that a fair proportion of the material, and the final test, focused around UK law relating to drink. There are obvious things to do with the age of the drinker, but I also learned that it is a specific legal offence to sell alcohol to someone who (in the considered opinion of the seller) is already drunk. Too much like shooting fish in a barrel, I suppose. Most of the laws fit around common sense, though as with any body of legal material you are left a little perplexed as to why specific conditions were imposed.

Russian troops and Finnish smugglers, 1853 (Vasily Hudiakov, WIki)
Russian troops and Finnish smugglers, 1853 (Vasily Hudiakov, WIki)

Anyway, all this set me thinking about law and qualification. The government of the day, however it was decided, has for a very long time indeed decided that it is entitled to a certain proportion of the profits from various kind of sales – and alcohol has typically been way up the list. And of course where rulers try to enforce a ruler, some subjects will concoct cunning schemes to get around the additional expense – excise duty spawns groups of smugglers almost by definition. But you only risk smuggling goods where the financial equation makes sense – small, easily concealed items where the tax duty is high enough that you can pocket a decent cut for yourself, while still leaving the buyer feeling they have done very well out of the deal.

So customs duties, and the body of regulations which underpin them, have been around for millennia. And – typically – part of those regulations consists of ways to appoint specific individuals as those few who are allowed to make transactions. In days of old, one suspects that many of these appointments were based on nepotism or bribery… if you had the right connections, or could stump up enough starting cash, you could find yourself in a comfortable position and set up for life. Nowadays the process is rather more transparent, and the barriers to entry are very much lower.

The Jolly Sailor, Bursledon (www.jollysailoroldbursledon.co.uk)
The Jolly Sailor, Bursledon (www.jollysailoroldbursledon.co.uk)

But equally, things have been tightened up in other ways. A couple of hundred years ago, it was fairly common for ex servicemen to use their prize money, or sign-off pay, or whatever they had saved up, to buy a little inn somewhere, and make a tidy living brewing or distilling booze of widely varying quality, and plying locals with the results. (Any pub you find called the Marquis of Granby recalls charitable donations by this 18th century gentleman who donated money to wounded servicemen). Provided you could afford a small building and a few bits and pieces to do the fermentation, you could set yourself up, no questions asked. These days, you have to go through hoops like planning permission, health and safety, police, plus of course getting a premises licence. There are all kinds of reasons why an apparently sound business plan might be rejected by officialdom.

The ISS (NASA/JPL)
The ISS (NASA/JPL)

So that is looking back… but what about forwards? Right now the only human outpost we have away from the Earth is the ISS. It’s not very far away – about 400km above the surface of the Earth, less than the distance from one end of England to the other. And I don’t suppose that the occupants have much privacy or opportunity to set up fermentation or a distillery up there. Though I did hear today that Budweiser has funded one of the science experiments on board, seeking to improve strains of barley with increased resistance to environmental stress. So maybe next year someone wil fund a experiment to make beer up there and see how yeasts behave in microgravity!

Alexa Far from the Spaceports logo
Alexa Far from the Spaceports logo

But let’s assume that within the next couple of decades we have an outpost or two somewhere else – the Moon, say, or Mars, or even a privately operated space station. How likely is it that nobody will attempt to ferment fruit or vegetable juices? And whose laws will be applied to regulate such an operation? Now run the scenario on a few more years, into the solar system I imagine for Far from the Spaceports and its sequels. There are a decent number of scattered habitats, each separated from the others by at least days, often weeks, and sometimes months of travel time. It will, I suspect, become impossible to try to enforce some kind of uniform system of laws.

Alexa Timing logo
Alexa Timing logo

My guess is that each habitat will have its own local set of laws and customs – no doubt broadly consistent with each other, but differing in detail. Sure, you can send a message anywhere in the solar system within a day at most, but if you get a tip-off that the habitat on Charon is bootlegging some kind of moonshine drink that is not allowed on the Moon, it’s going to take your police three or four months to trek out there and investigate. Will they bother? In that kind of situation, I don’t think it is feasible to try to maintain a single unified system of laws and regulations. So now suppose I have trained for my personal alcohol licence here on Earth (which in fact I did), and then decide on a whim to travel out to Charon. Will a publican out there recognise my licence? Or will he or she make me study for a duplicate one, ending up with a signature of someone on Charon rather than Earth? Right now, in the present day, it is extraordinarily hard to transfer qualifications between countries in professions like teaching, nursing, psychotherapy, and so on – will things be any different when we’re scattered across a few dozen habitats? I suspect not, especially as my own new licence doesn’t even allow me to do stuff in Scotland!

All of which is why I like writing about that near-future band of time, when there is no Federation, no Galactic Empire, or whatever – only local enforcement of issues according to moral and social principles which makes sense to the occupants. I suspect the chief coordinating factor would be economic – if you felt that some particular habitat was doing things the wrong way, you wouldn’t trade with them. They would become isolated, and there’s nowhere in the solar system away from Earth that can actually be self-sufficient. Hence I write about economic and financial crime, as these are the things that seriously threaten lives and livelihoods.

Compost

Mars from about 1000 miles, as seen by CubeSat MarCO-B (NASA/JPL)
Mars from about 1000 miles, as seen by CubeSat MarCO-B (NASA/JPL)

Before I start on compost, here’s a remarkable picture of Mars taken with a fairly ordinary camera, from a spaceship about the size of an average briefcase. Called a CubeSat, two of these were launched alongside the Mars Insight probe, and whistled past Mars while said probe made its way to a safe landing. More about Mars later…

It’s the time of year when – at least in the northern hemisphere – you put compost on your garden as part of bedding it down for the winter. These days that’s generally easy – you trot along to your local garden centre and get 3 bags for £12, or whatever the deal is, and you spend a suitable amount of time distributing it around your little patch. Someone else has done most of the hard work of transforming original plant and animal matter into an easy-to-use commodity.

But in a big garden you can do things a bit differently (and if you’re a farmer, you’ll be up into another league altogether, which I am not going to presume to write about). You can gather up said plant and animal matter yourself, stow it away somewhere dark and warm, add whatever extra bits and pieces you want, wait the better part of a year… and there you have your own compost. Which is what has been happening up here in Grasmere – last year’s rotted stuff, including pig manure, was ready for distribution. Not only that, but all those leaves which have been building up in the garden got put into the compost bins, waiting for their turn next year!

Now, this process has been going on pretty much ever since people discovered how to cultivate crops. Last year’s plant waste, together with stuff from whatever animals you had, and most likely human waste as well, got stashed away and spread on the fields when ready. The process has got steadily more scientific over the years, with additives to ensure that the ratios of chemicals are appropriate for the crops in question, but fundamentally nothing has changed.

Plants about to be harvested on the ISS (NASA/JPL)
Plants about to be harvested on the ISS (NASA/JPL)

But now think about what happens when you go out into space. You can grow some crops hydroponically, but this needs water which has been prepared with suitable levels of nutrients… which needs those nutrients to be available. We’ve done it up on the ISS, where the astronauts have prepared bits and pieces of salad to accompany their regular rations. But most of what is eaten in orbit has had to be carried there in a cargo supply ship. Suppose we add a couple of large modules on to the ISS and start growing things on a bigger scale. Then maybe we just need to ship the nutrients up there. That helps.

Now go a bit further. You have built a moonbase, or are living in a dome on Mars, and you want to grow your own stuff. In one sense you are surrounded by soil, but it is totally lifeless soil. It probably has a number of the basic chemicals you need, but none of the complex organic substances that your plants need. So you’re back to shipped-in nutrients… until you have either built up some human waste (and allowed it to decompose in some suitable way), or waited a year for the spare bits and pieces from one year’s harvest to rot down into compost.

Cover - The Martian (Goodreads)
Cover – The Martian (Goodreads)

This is probably reminding you of The Martian – Mark Watney manages to grow potatoes using the left-behind waste of his fellow crew-members. It goes pretty well until an accident exposes all his carefully prepared plants and compost to sub-zero temperatures and an air pressure less than that on Everest… which kills the lot and causes him to revert to Plan B (or probably, Plan F by that stage in the book). All necessary stuff, and emphasising the point that to grow Earth plants, you have to have built up a stock of Earth compost to encourage their growth.

So as I was piling leaves into the compost houses to being their long process of rotting down for this time next year, I suddenly wondered about our future. Out of all the unlikely cargos to be shipped out to our future colonies out on the Moon, Mars, the asteroids, and wherever else, wouldn’t it be supremely funny if most of them were shipping out the raw ingredients to make compost? Not an eventuality that makes its way into fiction very much… but how else are you going to grow your food?

The Compost Houses sitting waiting for next year
The Compost Houses sitting waiting for next year

Fire

The empty fireplace
The empty fireplace

This week I helped swap over an old wood-burning stove for a new one. As has been my experience of all practical jobs, what had promised to be a fairly straightforward out-with-the-old-and-in-with-the-new process ended up having unexpected wrinkles. The chimney pot also needed replacing (since the old fire didn’t draw very well), and a new chimney liner had to be put in. And there was an old liner which had to be pulled out – both liners follow a chimney which is about ten or eleven metres high, so these were interesting tasks in themselves.

The new fire installed
The new fire installed

Then an old hearth had to be taken out (which has already happened in the picture above, thanks to the very large drill on the floor, plus a sledgehammer and other hefty tools). Then the new stove had to be moved into position and the exit pipe fastened to the chimney liner with suitable gunk.

Then the paintwork had to be touched up where it had been bashed about by all this. And finally the copious amounts of dust – from stone, soot, brick and ash – had to be cleaned up on pretty much every surface in the room!

The story has a happy ending – the new fire really does light, as you’ll see below, and early impressions are that it is doing a better job than the old one. But while doing this job, I had plenty of time to contemplate fire. Or more widely, energy.

There are some places on planet Earth where people can live without using any energy source for heating, though most places need something at least in wintertime. But every society that I know of, world-wide, has harnessed fire for cooking. This isn’t just for aesthetic or culinary satisfaction – the process of cooking food makes a much wider range of nutrients accessible to our digestive system in much more reliable quantities. So the harnessing of fire for cooking – something like a couple of million years ago, give or take – liberated our hominid ancestors to get on with other things rather than have to forage endlessly. They could prepare food so as to use it more efficiently, and store it so as to survive lean times.

The Venus of Willendorf, c. 30000 years BCE (Wiki)
The Venus of Willendorf, c. 30000 years BCE (Wiki)

They could invent fish hooks and jewellery in their spare time, create artwork and conduct sacred ceremonies. (They also designed weapons of increasing effectiveness, and social orders which exaggerated differences in wealth between individuals, but we’ll skip over that for today). The use of fire for cooking seems to coincide with one of those great leaps forward in the often-slow process of human development, signalling this opportunity for our remote ancestors to explore and comprehend their world with intelligence.

Cover - In a Milk and Honeyed Land
Cover – In a Milk and Honeyed Land

All this happened in remote prehistory – long before the Late Bronze Age of In a Milk and Honeyed Land and its sequels, and long before the Langdale world where Quarry will be mainly set. By those times, fire and cooking were established parts of life whose origins were lost in the unfathomable world of the ancestors. But fire – energy – has remained a key part of our expanding world. Our ability to inhabit every part of the world has relied totally on our ability to maintain adequate warmth in our houses. An unprotected human in the middle of an Antarctic winter wind would die within thirty minutes at most, and would be crippled long before that.

A wood-burning stove is basically a very old bit of technology – except the one I helped with was made of metal, which pushes the date much more recent. But the problem it is helping to solve is perennial. Nowadays we don’t actually need to burn wood to generate heat, though many people find the experience of being warmed by an actual fire to be more comforting and engaging than just switching on a radiator. Energy from many sources is fed into our electricity grid – coal, water, wind, oil, nuclear, solar – and whatever the source, it runs an electric fire very nicely. The choice of our national energy spectrum of sources is – and should be – made according to national and global considerations, not whether I personally happen to have one device or another.

Artist's impression, Juno probe near Jupiter (NASA/JPL)
Artist’s impression, Juno probe near Jupiter (NASA/JPL)

And the situation become more stark as we go out into space. Space, as well as being mind-bogglingly big – is a weird place. In one sense it is freezing cold – a warm body will radiate away energy at a steady rate. But in another sense it is full of energy – light from the sun, electromagnetic radiation, and down at a quantum level a whole sea of vibrant energy just waiting to be collected. Whether we send out a robotic probe like Dawn, or we go elsewhere in person, we either take our energy with us or we collect it from the void around. The Juno probe has huge solar power collectors – each of those three panels in the picture is about the height of a typical house – and it is operating  almost at the outer limit of where such solar panels can be used. Probes that go further from the sun must carry their energy with them, and when it runs out they will die.

Cover, Tau Zero by Poul Anderson (Goodreads)
Cover, Tau Zero by Poul Anderson (Goodreads)

Most science fiction writers assume that the spaceships that they write about can refuel somewhere in space – maybe by gathering up interstellar hydrogen as they travel about using one variation or another of an idea of the physicist Robert Bussard – Poul Anderson’s Tau Zero was a relatively early novel making use of a Bussard ramjet, and at some stage Star Trek script writers decided that this was how the Enterprise and other similar ships gathered fuel (alongside matter-antimatter reactions and dilithium crystals). That way your ship can carry on boldly going without the inconvenience of having to stop at a nearby starbase just to load fuel into the necessary bunkers.

However it’s done, people will continue to need energy – fire – wherever they go. I think it’s most unlikely that energy sources in my science fiction books look anything like a wood-burning stove, but whatever they do look like, they serve the same purpose.

The new wood-burner alight
The new wood-burner alight

Mars Insight lander and Elysium Planitia

A quick post today as I have been buried deep in coding web applications for Lake View Country House and its sister businesses. As an added bonus there will be an extract, this time from Timing.

Artist's impression, Insight on Mars (NASA/JPL)
Artist’s impression, Insight on Mars (NASA/JPL)

First though, the NASA Mars Insight lander. This is well on its way to Mars, and is due to touch down on November 26th (at around 3pm Eastern Time, or 8pm UK time). Landing on Mars has traditionally been a hazardous affair, and something like half of all probes sent there have not done so successfully. But things have improved recently, so let’s hope all goes well on 26th.

Now, Insight has a couple of primary science targets, both relating to the interior of the planet. One instrument will measure heat flow under the surface, and another will detect seismic changes – earthquakes if you like, though perhaps Marsquakes might be a better word. The overall intention is to get a better idea of what Mars is like once you probe below the dusty surface. To that end, various drills will work their way several metres down below wherever the probe ends up landing.

The site area on Elysium Planitia chosen for landing (NASA/JPL)
The site area on Elysium Planitia chosen for landing (NASA/JPL)

But it was the landing place that particularly caught my eye – a flat plain called Elysium Planitia, roughly straddling the equator. This was chosen for scientific reasons – it is mostly flat and has a suitable kind of surface layer for the instruments to work well. But interestingly, Elysium Planitia features in Timing (Far from the Spaceports Book 2) as the site for a developed, and particularly lively, habitat.

In that book, Mit and Slate visit a couple of places on Mars, as well as its tiny moon Phobos. Their first target is a training college close to the mountain Olympus Mons, and from there they move across to Elysium Planitia in order to meet an old adversary… who claims now to be an ally. The two sites are in stark contrast – the training college is austere and frankly dull (though helpful for Mit and Slate in deducing what has been happening), but Elysium Planitia is exciting to the point of excess… Insight will have a very staid experience in comparison…


The quayside at Elysium Planitia was busy and bustling, and didn’t exactly feel safe. I kept all my pockets sealed shut, held my bag in front of me all the time, and tried to stay alert. Slate had promised to keep a eye out for anybody trying to infiltrate at a virtual level. I was used to crowds in London, but they were well-behaved, in which individuals knew where they were going, and made a habit of slipping past each other without interaction. And, as Slate kept reminding me, I had been away from that environment for a considerable time now, and the various habitats I had visited more recently were comparatively empty. I was out of practice.

Here, there was a lot of intrusion into personal space. Men and women jostled past each other, and there was a sensory bombardment on every side, offering all kinds of goods and services. Nothing was free, and the price of the more personal interactions was, literally, astronomical.

The habitat was much the biggest one I had been to, making even the south lunar pole settlement look small. I focused on threading my way through the hustle, following Slate’s internal prompts for some distance from the dock towards a quieter, cheaper row of guest houses. All I wanted – all that Elias would expense for – was an economical, no-frills hideaway. All being well, I would be back to Phobos soon.

The place I selected had no human greeters, just an automated checkin service. I wasn’t paying enough to warrant a real person’s presence. Out in space, Slate had sighed about the frequent partings our job required. I was much more basic in my needs, and this was my complaint. I particularly loathed the need to keep staying in dingy soulless rooms.

My heart sank slightly when the welcome screen spiralled brightly coloured words at me: “We’re Like Vegas Used To Be! Only In Space! And Better!!” But the process of getting access to the room was easy to follow, and it didn’t take long. You just had to focus away from the vivid ads which pressed in from the edge of the screen just as soon as the system had decided that I was an adult.

Once I had successfully navigated that, I was given access to the room. It was secure and reasonably comfortable, and it got me off the streets well before the really busy evening time. I had no particular desire to just go wandering round in a fit of exploration. There was going to be quite enough excitement just meeting Jocasta tomorrow.

 

Dawn, death, and ion drives

Dawn takes off, September 27th 2007 (KSC/NASA)
Dawn takes off, September 27th 2007 (KSC/NASA)

Last week, NASA’s Dawn space probe, which first launched back in 2007, finally ran out of fuel and has been declared dead. Regular readers will know that Dawn has been a great source of information and inspiration for me as I have been creating the future world of Far from the Spaceports, Timing, and the in-progress The Liminal Zone. So it seemed fitting to me to do a kind of tribute to Dawn here.

So here’s a timeline of key events:

  • September 2007 — Launch
  • February 2009 — Mars Gravity Assist
  • July 2011 — Vesta Arrival
  • September 2012 — Vesta Departure
  • March 2015 — Ceres Arrival
  • June 2016 — End of prime mission
  • July 2016 — Start of first extension
  • November 2017 — Start of second extension
  • November 2018 — No remaining fuel: mission ends
Enhanced colour image of Ceres (NASA/JPL-Caltech/UCLA/MPS/DLR/IDA)
Enhanced colour image of Ceres (NASA/JPL-Caltech/UCLA/MPS/DLR/IDA)

Of course, Dawn is not going anywhere – it will remain in its current orbit around Ceres for decades at least, until some combination of inevitable gravitational perturbations distorts that orbit enough that it eventually crashes into the surface. But there will be no more navigation from Dawn, no more course correction, no more photos or science information.

I want to talk a bit about Dawn’s ion drive, in the connection of storytelling, but if you want pictures and information about the mission findings, the best place to start is the NASA site, which has separate pages for Vesta and Ceres.

So, the ion drive. Most craft up to now have used chemical rockets – two or more chemicals are stored separately, then mixed to form a high-energy burst of propulsion. For example, the latest SpaceX SuperDraco engine uses the two liquids nitrogen tetroxide and Monomethylhydrazine. The net effect is that the spacecraft is pushed with high acceleration in a particular direction. After this engine burn, the craft coasts with no further propulsion for days or months, until it’s time for another correction. Astronauts in the craft have to endure short periods of high g-forces, followed by long periods of weightlessness. The engine burns have to be very precisely calculated for direction, force, and duration, so as to minimise the need for subsequent burns. Once the fuel is gone, it’s gone, and each burn takes a fair proportion of the fuel stores.

Falcon Heavy launch, February 6th 2018 (SpaceX via Wikipedia)
Falcon Heavy launch, February 6th 2018 (SpaceX via Wikipedia)

What does this mean for storytelling? Well, most of the journey is spent at zero acceleration, coasting towards your destination without burning fuel, and without any sense of up or down. It took the Apollo astronauts about three days to get from the Earth to the Moon (and the same back again, after doing stuff on the lunar surface). As and when SpaceX or whoever sends another rocket there, it will still take about three days – the time taken is a result of the coasting period without power, not the force of the engine. And because of the long zero-gravity sections, you need to be fairly well-trained to manage this.

SpaceX 'Starman' orbit (SpaceX Twitter feed)
SpaceX ‘Starman’ orbit (SpaceX Twitter feed)

Now consider a trip to Mars. In February of this year, SpaceX launched a Falcon Heavy rocket, with payload of a Tesla car and suitable contents. It left Earth orbit and headed out on an orbit that goes out past Mars, but at a slight angle so that the two never intersect. Each orbit takes 557 days to complete, so at this point not even one has been finished. The payload – a Tesla car – passed by Mars orbit a few days ago, after about eight months.

The Hermes rocket from the film The Martian (http://the-martian.wikia.com)
The Hermes rocket from the film The Martian (http://the-martian.wikia.com)

Now, this rocket had not reserved enough fuel to slow down and enter Mars orbit – it was a vivid proof of concept for SpaceX, not a real attempt to land on the Red Planet. But basically, if a human crew does the same journey in the same rocket, it will take them about eight months to get there – eight months of zero gravity, unless rocket design changes to include a kind of pseudo-gravity produced by rotation, as in the Hermes spacecraft in The Martian.

Getting out into the solar system on chemical rockets just prolongs these figures. Potential astronauts have to cope with months, if not years, of isolation and low gravity. It is just not viable to send people there, which is why the present focus has been on sending hardware and instruments.

Schematic diagram of ion drive (NASA/JPL)
Schematic diagram of ion drive (NASA/JPL)

Enter the ion drive, as used on Dawn and a handful of other craft. It is, in some ways, the opposite of a chemical rocket. It produces small amounts of drive thrust continuously for a very long time. NASA estimates that the thrust of the engines on Dawn is roughly the same as what you feel when you hold a piece of paper on the palm of your hand. It’s quite useless for getting off the Earth’s surface – you really do need something powerful for that – but as a way to get you from Earth to Vesta… or Vesta to Ceres… From a standing start in free space, Dawn would take about four days to go from 0 to 60 mph. But that ion drive just keeps piling on speed. Dawn’s engine ran for a total of about 2000 days during the mission – over 5 years.

Artist's impression, Dawn at Ceres (NASA/JPL)
Artist’s impression, Dawn at Ceres (NASA/JPL)

Now, if you have an engine that is always-on, your whole picture of the solar system changes. Let’s suppose you keep accelerating to the mid point, then flip over and decelerate the rest of the way, so that you get to feel a constant gravity all the way. Then further is more efficient. In twice the time you can go four times the distance. Or, to put the same thing another way, to go twice the distance takes less than one and a half times the time.

Of course, Dawn’s motors were still early versions of the design, with a low thrust output even at maximum. For my stories, I’ve assumed that the design can be enhanced to give an acceleration equivalent to 1/20 of that at Earth’s surface – considerably less than what you get on the moon. It would take some getting used to, but it means that your body and brain have a clear sense of up and down, and all those physiological functions that need gravity have a good chance to keep going! What does this mean for travel time?

  • Earth to Mars takes between ten and twenty days, depending on their relative position at the time of launch
  • Earth to Ceres takes about 3 weeks
  • Earth to Pluto takes about three months
Timing Kindle cover
Timing Kindle cover

That works for storytelling – it’s not very different from journeys that people would take by sail back in the day. For example, an 18th century trip from England to India would take something like four to six months. Once the Suez canal was open, this reduced to about two months. People will put up with a journey like that for all kinds of reasons. So that’s roughly how you can imagine the solar system of my science fiction novels – a bit like our world was in the days of sail and early steam ships.

Here’s a short extract from Timing, in which journey time gets discussed a bit. Meanwhile, RIP Dawn!

Then, quite suddenly, I had been sent all the way to the Jovian system. That would have been fair enough after the local jobs, but it turned out to be a false alarm. One of the analysts thought he had seen a recurrence of an old scam, running out of the Callisto hub. So off we had gone – a long journey for both Slate and I, and when we left Earth orbit the planetary alignment meant there were no friendly stopovers to break the journey.

Once we got there, the two of us had poked around, wormed our way into this module and that, but found nothing. To be sure, we confirmed that the reported irregularities were real. We had easily managed to find the batch runs where the credit had gone missing, by comparing input and output. It happened every time a specific input value was missing or unreadable, and a default value had to be assumed. But the chosen default looked right and we couldn’t find root cause. The code was non-standard, and frustratingly weird, but there was nothing obviously suspicious. The logs were so skimpy as to be almost useless. It did not seem to be the kind of task that needed our skills, nor to be as much of a problem as the analyst had first thought.

When it was over, and having drawn a blank, we sent a summary report down to the Finsbury Circus office, suggesting that perhaps it would be more effective to send an accountant. We had managed to get four weeks out of the work, but it still felt like a long drag for not much return. To be fair, it was unusual for the analysts to make a mistake like that, so I was professionally polite rather than curt. Then it was time to warm up the engines of our sloop, the Harbour Porpoise, and off we set on the homeward leg.

I was all set for a boring journey back down the gravity hill to Earth, but Slate found an orbital option which would take us right past the Scilly Isles. That settled it. We deserved a reward for our fruitless diligence. So we changed the navigation plan, sent some messages ahead, and here we were. Elias, my manager back in London, had made a token protest at the diversion, but I told him that the Harbour Porpoise needed servicing and the delay was unavoidable.

Anyway, a couple of hours signal lag meant that we were already en route by the time his answer came back. We just said that we didn’t have enough reaction mass for such a radical course change. It might even have been true, though I was careful not to ask Slate for a technical analysis, and she was just as careful not to offer one.

Regardless of that, we weren’t minded to listen. Slate and I both reckoned that we deserved the break. Six weeks of voyage out to Callisto, and four weeks of fairly dull work had not made us receptive to a tedious trip straight back home again. It would mean nearly three months’ travel time for just one month of work, and we weren’t about to just put up with that without an argument.

Tesla Starman (SpaceX Twitter feed)
Tesla Starman (SpaceX Twitter feed)

Ultima Thule

Today’s blog is focused on the next target of the New Horizons probe, which back in July 2015 sent back such remarkable pictures of Pluto and Charon. But before that, here’s a quick reminder of this week’s Kindle Countdown deals for Far from the Spaceports and Timing – £0.99 / $0.99 for the next couple of days. Follow these links…

New Horizons route, including Pluto and Ultima Thule (Wiki)
New Horizons route, including Pluto and Ultima Thule (Wiki)

Right. New Horizons. After the Pluto flyby, the natural question was, what next? There was enough fuel and energy reserves to consider a small course change… but to what end? Pluto is at the inside edge of the Kuiper Belt, a tenuous and very sparsely populated volume of space. Over the last few years, we have been steadily gaining information about some of the contents, many of which have hugely elongated orbits. The big prize out there is the possibility of a really sizeable planet, acting as a gravitational shepherd to coax the smaller bodies into resonant patterns.

Planet 9 has not yet been found, but several smaller bodies have. And one of them, catalogue number KBO 2014 MU69 , happened to be well placed for New Horizons. So, an appropriate course change was made as Pluto dwindled into the distance, and KBO 2014 MU69 – now provisionally renamed Ultima Thule – became the next goal.

Current New Horizons view of Ultima Thule (NASA/JHUAPL/SwRI)
Current New Horizons view of Ultima Thule (small dot on right-hand frame) (NASA/JHUAPL/SwRI)

But distances out in the Kuiper Belt are large, so there has been a considerable wait. Ultima Thule is about 12% further away from Earth as Pluto is. The actual flyby will occur on January 1st next year, and at this stage we still don’t really know what to expect. The Hubble telescope orbiting Earth shows Ultima Thule as just a slowly moving point of light. New Horizons is about 33 million miles away from it – about 1/3 the Earth-Sun distance – and still can’t resolve it to more than just a point source. We cannot make out any surface detail. We don’t know if it’s roughly spherical, or irregular, or even a little cluster of fragments all moving together. Just about all we know is that it’s less than 40 km across, and although very dark by the standards we are used to in the inner system, is slightly more reflective than expected.

Artist's impression, New Horizons and Ultima Thule (Steve Gribben/NASA/JHUAPL/SwRI)
Artist’s impression, New Horizons and Ultima Thule (Steve Gribben/NASA/JHUAPL/SwRI)

After sending the Pluto and Charon data home, New Horizons went to sleep for a couple of years, with a wake-up call in June for some of the instruments and a course correction. It is now being prepared as best we can for the encounter. It’s a fascinating problem – light or radio signals take around 6 hours to cross the gulf between us and the probe, so there is no possibility of direct control.  Any reply takes another 6 hours to get back. The systems have to be set up in advance, according to our best guess of what will be there. The final course changes will occur in mid December, when the ground crew wil decide just how close to steer towards Ultima Thule. In one sense, the nearer the better… but the higher the risk that the probe will make brief, catastrophic contact with some fragment of rock and ice. On the day, the probe will whistle by at over 30000 km/h, so there’s no opportunity for second chances. Whatever sequence has been set up in advance, will be played out without modifications. After that, New Horizons will spend the better part of two years streaming the data back to Earth. So although the rendezvous will be a New Year treat, we shall have to wait a long time until we get any high-resolution images or other data.

As yet I haven’t written about what life might be like in a suitably protected environment out in the Kuiper Belt… maybe this encounter will be the seed of another book, in the way that the flyby past Pluto and Charon has contributed to The Liminal Zone. And here, just for a bit of fun, are someone’s first impressions of the settlement on Charon, extracted from the early sections of The Liminal Zone

Nina walked steadily along the winding curves of Lethe towards Asphodel. The house AI had finally told her where Lance’s quarters were situated in Acheron, and had transferred directions onto a hand-held to direct her there. From space, the overall shape of the Charon settlement had been clear – five sinuous linear habitats, following curves in the underlying terrain and joined radially to Asphodel. When you were actually down here, it wasn’t nearly so neatly divided. There were extra little corridors and alcoves which broke up the superficial symmetry, and little tunnels that dived underground and then resurfaced at unexpected places. She was glad that the little hand-held router buzzed faintly at junctions to tell her which way to turn.

Back to life on other planets…

Our solar system - comparison of sixes (BBC)
Our solar system – comparison of sixes (BBC)

It’s a while since I added to my occasional series concerning the exploration of life on other planets, so here are some thoughts about the giant planets in our solar system. Largest of all is Jupiter, followed by Saturn, then Uranus and Neptune. Each of these has a collection of moons, but I’ll deal with them another day. We also know of a number of exoplanets of this size circling other stars – big planets being easier to detect than smaller ones, other things being equal – but that’ll be the subject for another day.

These large gas giants are characterised by hugely deep atmospheres, in which the pressure rapidly builds to intolerable levels as you drop down through it. It is unclear whether there is a hard surface at any point, or whether the gases of the upper layers simply get progressively denser and more viscous with depth. With no obstructions to stop them, wind currents circle the planet and stir up giant storms that can last for decades. It is not an obvious place for life to thrive.

Spacehounds of IPC - cover (Goodreads)
Spacehounds of IPC – cover (Goodreads)

Science fiction writers have, nevertheless, speculated about life here. Some authors simply ignore what we know (or were writing at a time when much less was known), while others try to weave their stories alongside the facts as we understand them. Typical of the first is EE (Doc) Smith, who was never shy of hypothesising life anywhere, and took great delight in speculating how environmental pressures would shape an alien race’s outlook on life, as well as their physiology. He placed several races on gas giants, including Jupiter. Such races, in his view, would be not only squat and strong – to cope with the gravity – but arrogant and condescending towards the weaklings of other worlds. A large part of Spacehounds of IPC deals with a long-running war between the hexans and the Vorkuls, inhabiting two opposing cities and fighting an impeccable war against each other. The Earthlings help resolve the fight by siding with the more morally upright side – they have little enough in common with either, but the hexans turn out to be unacceptably vicious and ruthless.

The Algebraist - cover (Goodreads)
The Algebraist – cover (Goodreads)

Iain M Banks, on the other hand, tried to take a more nuanced view. A couple of his books – including The Algebraist, for example – present life on gas giants as essentially floating, by analogy with oceanic creatures here on Earth. Different kinds of life coexist at different levels of the multi-layered atmosphere. Some of these interact, for better or worse, and others never meet.

Current scientific thinking is less optimistic about life of these giant planets, preferring to think about their moons. That’s a subject for another day. But there was a fascinating piece of analysis I read recently, trying to tackle the question of whether denizens of the gas giants would develop space travel. Basically, the rocket problem is that of managing your fuel. You need a certain amount of fuel to send your object of interest – the payload – up from the surface to orbit. But the payload has a protective casing, which you don’t need in orbit but which weighs something. Then there’s the fuel you’ll burn, and the container holding it… and these also weigh something. So you need more fuel to push up all that lot… and so on. Think back to how small the Apollo moon landers were compared to the entire Saturn V launch system.

The most fuel-efficient way to accomplish this is to have booster stages that are used in the early part of the flight, and then detached when empty to reduce weight for the next stage. Until the advent of reusable vessels like the Space Shuttle, and more recently Elon Musk’s launch vehicles that return to a soft landing, all of these lower stages were single-shot throwaway items. Now, that’s a problem for us here, but in turns out to be a much bigger problem if you are starting from a larger planet. Even one twice Earth’s mass would present difficulties, and Jupiter has about 300 times the mass. Musk’s Falcon Heavy rocket can place about 50 tons of payload into low earth orbit. Taking off from Jupiter, the same rocket could only get 40 kilograms into space. Would a race of beings living on one of these gas giants – even supposing they wanted to look through dense layers of cloud to see what was outside and spark their curiosity – have the resources to embark on space exploration?

One of Cassini's last images of Saturn (NASA/JPL)
One of Cassini’s last images of Saturn (NASA/JPL)

Weather – away from Earth

Last week I talked about weather on Earth, both in fact and fiction. This week, suitably enough, it’s time to think about the other planets in our solar system. And there’s plenty to talk about.

Dust storm front, northern latitudes of Mars (ESA Mars Express)
Dust storm front, northern latitudes of Mars (ESA Mars Express)

The obvious first place to start is Mars – the atmosphere is thin there (ground level on Mars is about the same as 30 km altitude here, high above the Himalayan peaks), but it’s well able to have weather patterns. There are seasonal changes, with the polar ice caps (frozen CO2, or dry ice, rather than water ice) growing and shrinking as the planet tilts one pole or the other towards the sun. Then there are erratic changes, such as dust storms which can build up over a substantial area. The Martian opened with one such storm, and the book version had a second which threatened Mark Watney’s journey towards rescue (the film skipped over this one). In the real world, back in the summer, one such storm of vast proportions cut off communication between NASA’s Opportunity rover and mission control. The problem here is not actually caused by fierce winds buffering the craft, but that the dust has blocked its ability to capture sunlight and so generate electricity (the exact problem Watney faced late on in The Martian).

Storm on Saturn seen by Cassini probe, 2010 (NASA)
Storm on Saturn seen by Cassini probe, 2010 (NASA)

Venus has ferociously fierce winds, and if ever we try to build a permanent settlement on the surface there (which personally I doubt, since orbital or high atmospheric bases would probably suffice) then they will need immensely strong anchors, and extraordinary resistance to high levels of heat and acidity. There are outline plans at present for building a lander able to survive for a few months, rather than the few hours which is all that has been achieved to date. Jupiter and Saturn have no discernible surface – probably one exists, but the pressure would be intolerable well before you reached it. They also have huge storms spreading thousands of miles across.

Artist's impression, dust storm on Titan (PGP/Labex UnivEarthS/University Paris Diderot – C. Epitalon & S. Rodriguez)
Artist’s impression, dust storm on Titan (PGP/Labex UnivEarthS/University Paris Diderot – C. Epitalon & S. Rodriguez)

But several of the moons of the giant planets are more promising. Recently, dust storms were spotted on Saturn’s moon Titan… not sand as might be on Earth or Mars, but great clouds of organic hydrocarbon molecules are stirred up into its atmosphere. So there’s definitely weather on Titan, and pretty much everywhere else we look.

Moons like Titan have been known to have atmospheres for some time, but as well as this, our solar system contains a lot of small bodies which used to be thought of as entirely airless. Closer investigation has shown that many of these actually have very thin layers of air around them. In some cases these are probably generated by underground deposits of liquid and gas which slowly ooze to the surface and evaporate. In others, we don’t yet know how they came into being. But these discoveries are reshaping how we think of our sibling worlds, and by extension the worlds we are spotting around other stars.

New Horizons image of clouds on Pluto (NASA/JPL)
New Horizons image of clouds on Pluto (NASA/JPL)

Back in 1950, EE (Doc) Smith, in First Lensman, could describe Pluto as being rocky and entirely barren. We couldn’t say that any more, not after the New Horizons probe sent back this fantastic image of air and clouds above Pluto. In Liminal Zone, my protagonists on Pluto’s moon Charon witness such changes both outside the dome where they live, and also when they look up at Pluto. Weather, it seems, is pretty universal, and will go on forming a topic of conversation for a lot of years to come.

And in a final stop-press, the existence of a new dwarf planet has just been announced. The finders were actually looking for the enigmatic Planet Nine, whose existence is suspected from a variety of gravitational anomalies in the orbits of other far-out objects. That has still not been detected, but instead they found 2015 TG387, dubbed The Goblin for simplicity. This newly recognised member of our solar system has a fantastically elongated orbit. At closest approach it is still well outside the orbit of Pluto, and at aphelion it strays 35 times as far away. It takes around 40,000 years to complete an orbit: last time it was in its present position we were sharing much of the planet with Neanderthals.

Orbit of 2015 TG387 (Roberto Molar Candanosa and Scott Sheppard, courtesy of Carnegie Institution for Science)
Orbit of 2015 TG387 (Roberto Molar Candanosa and Scott Sheppard, courtesy of Carnegie Institution for Science)

Red dwarf stars, and life away from Earth

After a few weeks in which I have been thinking about ancient Cumbria, this week I’m back in space again. In particular, this post looks at some possible locations for alien life which, until recently, were considered most unlikely. Over the last few years, thousands of planets have been identified by equipment both on Earth’s surface and in orbit. We now know that planets are exceedingly common in the galaxy, and that on average, each star has more than one planet. There are more planets near us than stars. Many of these are large in size, gas giants like our own Jupiter and Saturn – larger planets are obviously easier to detect than smaller ones – but a great many are small and rocky, more like Earth.

Artist's impression - the seven planets of TRAPPIST-1 (ESO)
Artist’s impression – the seven planets of TRAPPIST-1 (ESO)

The most extreme case we know of is designated TRAPPIST-1 (the acronym originating from the Chilean telescope which first detected them). This has seven planets, so the system is broadly like our own. And a very recent analysis suggests that each of them has liquid water at its surface, and in some cases considerably more water than we enjoy here. If we were to travel the forty light years to get there, we might well find a world which is entirely ocean.

But as well as the striking nature of the planetary system, the sun itself is interesting. Up until fairly recently, the search for life elsewhere was focused on stars which were as similar to our sun as possible. It was assumed that this was necessary in order for the associated planets would be like Earth. But TRAPPIST-1 is not at all like our sun – it is a comparatively cool red dwarf star. Red dwarfs are extremely common in space, but they are small and dim, and until modern orbital telescopes revealed the true situation, were thought to be rare.

Comparison of solar system sizes (ESO)
Comparison of solar system sizes (ESO)

Now, red dwarf stars are much cooler than our sun, between 1/3 and 2/3 of the effective temperature, so for a planet to be in the Goldilocks Zone – neither too hot nor too cold – it must be much closer to its sun. But that’s OK – in the TRAPPIST-1 system, all seven planets orbit well within the distance that super-hot Mercury circles our sun. Indeed, that system is not much larger than that of the moons of Jupiter. Red dwarfs are miserly with their energy, so you have to huddle in close to the fire to get any warmth. But along with that, they burn at their low rate for a hugely longer time than our sun will last. The hotter and brighter the star, the less time it shines for. Too short a stellar lifetime, and their might not be time for life to develop on whatever planets are around. Red dwarfs give their planets massive amounts of time to develop.

Right now we have absolutely no idea whether any of the TRAPPIST-1 planets supports life – or indeed any of the myriad other red dwarfs and their planets in our quadrant of the galaxy. But if you were a betting person, you’d be more likely to bet on life arising around a red dwarf than a super-hot star like Sirius.

Artist's impression, Ross-128b (ESO)
Artist’s impression, Ross-128b (ESO)

Now, 40 light years is inconveniently far away from Earth for exploration in reality or fiction. Our current generation of telescopes can find out a decent amount of information about the 7 planets of circling TRAPPIST-1, but not nearly as much as one would like. And if you consider near-future science fiction, without warp drives, wormholes, or other exotic ways to travel around space -as I do – then 40 light years is well beyond a realistic journey time. Happily, there are other red dwarfs much closer to us. One of these, which has been studied with great excitement for a few years now, is called Ross 128 (the rather boring name coming from a catalogue number). It has at least one planet (Ross 128-b) which appears to be a little larger and more massive than our Earth, and some calculations suggest that its surface temperature may well be around 21C. Ross 128 is only about 11 light years from Earth, so is getting towards the we-might-send-something-there territory.

I thought about using Ross 128 as the focus of interest in my in-progress novel The Liminal Zone, but in the end pitched for the even-closer Gliese 411 – another catalogue name, which for fictional purposes has been rebranded something more interesting. Gliese 411 is under 9 light years away, and is the 4th-closest star system to us. The planet Gliese 411b is, so far as we can tell, larger than Earth, and almost certainly rather hotter, but (probably) not so hot as to preclude interesting things there. And its proximity to us makes it a credible target for the Breakthrough Starshot project, in which tiny “spacecraft” with roughly the capability of a mobile phone are boosted towards their target by a laser beam shining against a light-catching sail. The miniature spaceships are called Sprites, and last year were tested for their ability to communicate from space after being launched from Earth. Each is just a few centimetres square, weighs just 4 grams, and costs a few tens of dollars. The entire actual cost of the mission is in the devices needed to boost these Sprites to their final speed.

Starshot’s current plans are for Proxima Centauri as target – the nearest star to us, a little over 4 light years away – and a boost to 1/5 light speed. Proxima Centauri is in fact another red dwarf star, and a very recent theoretical study suggests its planet may have a large ocean and survivable temperatures… though so far we lack real observations which might confirm or refute this, and other studies have suggested that the radiation levels are uncomfortably high for life to thrive.

My fictional version is a little more ambitious – Gliese 411 and 1/2 light speed. A journey time of about 17 years, plus the time taken for the homeward bound signal on arrival, means about a 25 year lag from lift-off to analysis of results. It’s still a long time, but less so than some space projects – it is now over 41 years since the two Voyager spacecraft left Earth, and we are still following them. A very recent theoretical study

As to what happens in The Liminal Zone once these little ships get there – well, it’s still work in progress, but hopefully you’ll get a chance to see for yourself early next year!

The Liminal Zone (temporary cover)
The Liminal Zone (temporary cover)