The populist authoritarian tribe of the demagogue


I came across a piece by the Guardian encouraging its readers to break out of their bubbles and go read the views of those on distinctly republican websites, such as Reason or the American Conservative. While I appreciate the intent, the fact is there’s not much point. Regular readers of this blog will probably notice I occasionally reference these websites myself. The problem is that conservative voters don’t believe in conservatism anymore, Trump proves that.


One could characterise republicanism as founded on four pillars – religious conservatism, a belief in small government, fiscal conservatism and strong on security. Trump breaks all of these rules. He’s a thrice married sex feint who thinks married women are fair game, fantasises about his own daughter and may have raped multiple women (or so they allege). There’s a big question mark over his religious beliefs, he is certainly not a…

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What worries me about UK energy policy


Figure 1: Thanks to the roaring Forties South Australia is installing increasing amounts of wind energy [Source:, ND]

There was a serious black out incident in South Australia last month due to high winds. Inevitably the anti-wind farm brigade were quick to blame wind farms and inevitably the media (who don’t know any better) were soon parrotting these claims. Is any of this true? No, not in the least. South Australia has seen a significant rise in renewables, in particular wind power over the last few years. They are now supplying 27% of the state’s electricity. However the fact is that the wind farms stayed up and running through the high winds and that it was the collapse of several powerlines that actually caused the black outs.


Figure 2: Wind power has at times met a significant proportion of SA’s electricity demand []Source: The covnversation, 2015]

This is what worries me about UK energy policy. On the one hand there would be a silver lining to any possible power cut, as it would allow experts like me to rub it in the government’s face how they’d screwed up royal by failing to adopt a long term energy plan. I mean one of the first things Theresa May did in office was to close down the DECC! The UK should be prioritising energy efficiency in the first instance along side a strong push to roll out as much renewable energy as we can. Other countries have shown the way. At the same time there’s a need to build in more energy storage and distributed on demand generation (i.e. more CHP, ideally biomass powered at the expense of large fossil fuel power stations) to reinforce the grid against any possible interruptions to supply. However my fear is that the tabloids will inevitably blame wind energy and renewables, regardless of the evidence to the contrary.

And it almost happened a few years ago. In the middle of a powerful storm in October 2013, several power lines came down which connected one of the UK’s nuclear plants to the grid. This forced the plant’s two reactors offline. To make matters worse another nuclear station was also offline for repairs (this is the problem with the UK’s ageing fleet, they are much more fault prone) so the UK suddenly was left with a short fall of several GW’s of power. Fortunately, there was enough spare capacity between gas , hydroelectric and wind power to plug the gap. Although a number of the UK’s wind farms did have to derate as the winds peaked (although this didn’t happen to all of them and not all at the same time), given the high winds the UK’s wind turbines were doing quite well through that night.


Figure 3: UK grid mix during the St Jude’s day storm [Source:, 2013]

However, the headlines in the newspapers next day wasn’t “wind & hydro power helps saves the UK from nuclear power black out”. Instead they focused on how one small wind turbine (the sort which a farmer might use to go off grid, not the big multi megawatt units) had fallen down in the high winds. They focused on how some of the wind farms went down for an hour or two (again not all of them and not all at the same time). Very few even mentioned the fact that a nuclear plant had gone offline and indeed was still offline a week later. Fewer still mentioned the reason why it was shut down (nuclear powerplants need electricity from the grid to power cooling pumps and control systems, they are forced to shut down and switch to backup generators if there is any interruption to their power supply, Fukushima was caused by the failure of those generators due to a Tsunami).

My fear is that regardless of the facts (we after all in the post-truth era), if there is any sort of a power cut in the UK, instead of accepting they need to change policy, instead the Tories will use it as a battering ram to implement the changes they want. They’ll probably try to stop power companies installing wind farms, ban solar panels, etc.. Keeping in mind there’s still some construction ongoing despite the subsidy cuts because energy companies see wind energy as a hedge against future high gas prices. They’ll throw yet more money at the nuclear lobby and shale gas drillers. And of course they’ll renege on the Paris climate treaty. Will this solve anything? Of course not, Hinkley C has taken ten years to plan and will take at least another ten to build (assuming its not delayed again) and produce some of the most heavily subsidized and expensive electricity in UK history. How in blue blazes will more of them solve a power shortage this winter or the next?

So there is a need to confront this reality in advance, the UK energy policy is a recipe for disaster. It is going to lead to less reliable and more expensive energy in future. It is going to make meeting the obligations placed on the country by the Paris accords impossible. This is a known fact, it has been pointed out to the government on numerous occasions. If there’s a power cut this winter, or anytime over the next few winters, it is the not the consequence of adding more renewables to the grid (not sure if the Tories have noticed but renewables “generate” energy, how can having more of something that generates power cause power cuts?), but the failure of the government to come up with a coherent policy, as well as their constant pandering to the climate denial brigade.

Posted in clean energy, climate change, efficiency, energy, Global warming denial, politics, power, renewables, sustainability, sustainable | Tagged , , , , , , | 3 Comments

The case for space – Part 3: Martian delusions


Figure 1: Mars One, serious vision or fantasy….or scam? [Source: Mars One, 2014]

I previously discussed the idea of colonising space as a possible solution to climate change and a future resource crunch. I think the conclusion would be that its not really a feasible solution. Yes, I have no doubt space exploration (as opposed to colonisation) will continue and I would argue that any money spent on space science is money well spent. But migrating large numbers of people off the planet, or start to mine other worlds for their resources just isn’t an economically feasible or practical proposal. It is therefore worthwhile looking at some of the proposals for colonisation doing the rounds on the internet, most notably Mars One, as well the proposed missions from the Mars Society and Elon Musk.

Mars One

The central theme of Mars One is “Mars to stay”. They propose a one way mission to Mars, with no immediate return option. There is perhaps an immediate fallacy in this plan – that a one way trip will be cheaper and easier. Actually, the opposite is likely to be true. Think about it, if you have no line of retreat, you need to build more redundancy into all of your hardware. You’ll need to stockpile spares in case something breaks down (a two way mission can simply abort and return to earth, a one way crew lose this option, as it will take months to get replacement parts out, spares will have to be stockpiled). If you’re only planning to send say 4 astronauts to Mars for thirty days, you can get away with a smallish lander. If they are going to be living there for the rest of their lives, it will need to be physically bigger, you’ll need more than one to handle a larger crew (there’s a minimum number of people you’d need for a permanent colony to work, likely at least 20).

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Figure 2: Mars One in a nutshell [Source: MIT (2015), via]


Figure 3: Mars One compared to Apollo [Source: MIT (2015), via]

Given the impossibility of maintaining any such colony without resupply (as I discussed in a prior post), they will also likely need resupply from earth. So rather than sending one team of astronauts to Mars, were launching multiple cargo ships there on a regular basis. This will very quickly start to stack up in the cost department. And there’s all sorts of hardware that they’ll need that has never been developed, nor flight tested. Even simply landing on Mars with their proposed lander would present all sorts of challenges.


Figure 4: Mars one cargo requirements. Note the growing percentage of ECLSS (life support) spare parts [MIT, 2014 via]

Now nobody’s saying its impossible, its just there’s a whole bunch of development costs they’d need to go through before they got to the stage of working hardware….which would presumably have to be flight tested multiple times to prove it can work, before a human crew is sent out. Add up the costs of this and suddenly the costs of a Mars One proposed mission start to balloon to levels that make NASA’s proposal’s look cheap.

The wrong stuff

All of this is not helped by Mars One’s frankly bizarre proposals for crew selection. They have relied on various individuals who’ve applied over the internet. Their shortlist includes in its top ten or so, a Libertarian bitcoin bug, a motivational guru and a fifty year old Sushi chef. Not exactly the right stuff! They also have an insane system whereby prospective astronauts can bump themselves up the rankings by buying sweatshirts and other merchandise. When perhaps they should be ranking them on the basis of technical knowledge, skills and experience (which is more important, being able to cut sushi on a planet with no fish….or being able to steer a spacecraft down to a safe landing?), the outcome of physiological profiles, etc.


Figure 5: Mars One crew selection [Source Outerplaces, 2015]

As anyone who as ever read up on the history of the Apollo programme should be able to tell you, it is crucial the right people are sent on such a mission. This is not a place for amateurs, space does not suffer fools. The last few minutes of Apollo 11’s descent to the Lunar surface being a case in point. As the LEM approached the moon, a whole bunch of alarms started going off and nobody knew why (it later turned out the computer had effectively crashed because it was getting too much data and couldn’t cope). Neil Armstrong about the same time recalls looking out the window and seeing they were heading for a hard landing in a boulder field. Fortunately, NASA had a kick ass crew on the case. They took manual control of the LEM, boosted away from danger and brought the LEM down to a safe controlled landing, likely with just seconds of fuel to spare.

Now Neil Armstrong and Buzz Aldrin pulled that off because they were highly trained and experienced astronauts. They had both been intimately involved in the development of the LEM throughout its design life (Mars One seem to think they can order this sort of hardware out of an RS catalogue!). Armstrong even survived crashing a LEM training vehicle. They knew their craft inside and out. And ultimately, they had an abort option available if everything when pear shaped. Mars one will be several light minutes away from earth, meaning that either they’ll have figured it out or crashed before mission control can do anything. They will have no abort options, they’ll either crash and die…..or land safely and die later!


Furthermore, as I discussed previously it is far from proven that its possible for humans to live on Mars permanently. Long duration stays are a possibility, but permanent residence, given the radiation and low gravity they will be exposed to, is a different kettle of fish. Inevitably over a long enough time period the probability of a Mars One crew’s survival drops to zero. If they crash on landing, they’re dead. If any of their key hardware fails, they’re dead. If a key person with technical skills (e.g. the mission doctor or engineer) gets sick, he’s dead, then so is everyone else once nobody’s left to do his job. If they can’t complete a viable life support loop, they’re dead. Given they will lack a line of retreat, its a case of just rolling the dice often enough and eventually we get a TPK.

The supporters of Mars one claim they will fund it by selling TV rights of their mission. The PR generated will inspire generations. Actually the opposite is likely to be true. A Mars one mission, where the public watches the slow gradual drawn outdeaths of a team of astronauts one by one would likely be a PR disaster. And no TV studio is interested in commissioning the most expensive snuff film in history. An MIT study (the same one referenced earlier) even suggested the crew would be dead 68 days after their arrival.


All of these inconvenient facts, the lack of anyone with the appropriate technical skills on the Mars One team has led some to question if its all just a massive scam. One of the few team members with in anyway credible qualifications, quit not too long ago, citing issues he had with the ridiculous way they operated and he openly question the credibility of the whole thing

Now I’m not sure if any of this proves its a scam. There’s enough demented space cadet’s around that its possible those behind it are sincere….and a perfect proof of the Dunning–Kruger effect. However to say there’s a few holes in this proposal is to put it rather mildly. It is no surprise that nobody seems to take Mars one remotely seriously.

Mars Direct and Elon Musk

I was originally going to do a separate analysis of both the Mars Society‘s plans, notably Robert Zubrin‘s Mars Direct and Elon Musk’s more recent proposals. However, given that they are broadly similar, I though it would be sensible to combine the two. Certainly, no doubt that both of these plans are significantly more plausible than anything proposed by Mars one.


Figure 6: Mars Direct proposal: The return vehicle (left) and habitat (right) [Source: NASA spaceflight forum, 2013]

The Mars direct plan involves sending a return vehicle out to Mars fuelled with several tons of hydrogen fuel and a small mobile nuclear reactor. This would then spend a year processing the Martian atmosphere to produce a mix of methane and oxygen, sufficient to fuel the return vehicle for the journey home. Once this vehicle is ready and fuelled, a habitat is sent out along with the astronauts. Once there mission is completed, they return in the already fuelled lander. It should be noted that Mars direct is intended to support Mars exploration, as opposed to colonisation. Although given that we’ll be leaving behind plenty of hardware that could be reused by future travellers, its possible it could form a stepping stone towards colonisation.

Elon Musk’s plans are a bit more ambitious, as he’s planning to send larger numbers for longer stays, leading to eventual colonisation. A extremely large reusable booster rocket will lift either an interplanetary vehicle (or a refuelling tanker) up to orbit. This rocket will be huge, with an LEO throw capability of 300 tons (by comparison the Saturn V could only manage a puny 110 tons) and will be powered by 42 first stage engines, running on the same Methane/LOx mixture mentioned earlier. This booster will be reusable, with the first stage flying back to its pad after staging and landing right back from where it started off.


Figure 7: Elon Musk’s Mars launcher on the pad.

Once in orbit, the Interplanetary craft is fuelled with further launches (using a reusable tanker). It will then head off for Mars and land on the planet. It will then be refuelled in the same manner as discussed for Mar direct, before returning directly to earth. This offers various options in terms of staying on Mars or returning.


Figure 8: SpaceX’s proposed launch sequence [Source:, 2016]

There are a couple of immediate criticisms and questions one must immediately ask, as this space scientist discusses. However I would take a step back and mention a few more obvious practical problems.

Firstly, why fly the booster back to the launch tower? Why not fly it back and land it at some other location? Why not do parachute recovery into the ocean like NASA does with its SRB’s? After all, what if it, say, crashes into the launch tower (or the tank farm!). Already SpaceX lost a few rockets in tests due to retrofire failures or legs failing to deploy. And any accident would jeopardise the mission by paralysing the launch process. Also the rocket would need to be checked out and inspected prior to re-use. So presumably you’d land it somewhere else (on the top of a barge or crawler vehicle) take it indoors for such checks and repairs, then deploy it to the launch site. Not least because Florida (from where they propose to launch) is prone to hurricanes and storms. And speaking of which, why not move down closer to the equator, such as the ESA launch centre in French Guiana? This would be a more fuel efficient location to launch from.

As Jeff Bell recently pointed out, Elon appears to be channelling Sergei Korolev and copying his failed N1 booster. This rocket, used the same idea of clustering multiple engines around a single rocket stage, meaning you’re rolling 42 dice every time you launch and running the risk of one or two engine failures destroying the launch vehicle. With the N1 this configuration meant it proved impossible to test fire the whole assembled rocket on the ground, so they had to work things out in actual test flights…..four extremely expensive and embarrassing failures later (including one of the largest non-nuclear explosions in history) and the Russian manned lunar programme was finished before it even started. Jeff Bell also discusses the extremely ambitious design of the proposed Raptor engines, which will use a staged combustion process operating at extremely high chamber pressures. Not exactly the sort of thing that would boost reliability.


Figure 8: The Russian N1 Rocket [, ND]

But I would raise a more obvious question, why use Methane/Lox for earth ascent and trans Mars Injection? Surely LH2/LOx with an Isp of 450s v’s the 360s he’ll get from his raptor engines (if they don’t blow up!), would be a better idea? His proposal incurs a massive weight penalty right from the start. In theory the only bit of the vehicle that needs to be powered by LCH4/LOx is the section of the flight where astronauts are boosted back up off Mars (or where fuel is ferried up for the transfer vehicle’s flight back to earth). This would have the additional benefit of cutting down the weight landed on Mars considerably, as we’d only be taking a small capsule up/down v’s the entire spacecraft.


And since we’re talking about it there’s a certain swiss army knife nature to this Interplanetary vehicle. It has to withstand launch on a booster from earth (carry the crew one assumes), keep the crew alive for many months on end by meeting all of their life support requirements. It has to survive re-entry through both the Martian atmosphere and the Earth atmosphere (and do both in the one mission, sitting on Mars exposed to the elements for several months prior to return to earth and doing a re-entry there). It must be capable of boosting itself off Mars and perform the Trans Mars and return injections. That’s an absurdly long list of mission requirements.

Playing around with the numbers from Musk’s proposal shows its going to need a mass fraction of at least 0.19, not far off that for an SSTO. I discussed the technical difficulties of developing such a vehicle in a prior post. But in this case Musk is lumbering his vehicle with a whole raft of additional requirements (notably several months of food and consumables has to come out of that 19% mass budget….along with any any payload and crew….and the vehicle’s empty weight as well!).

To my mind breaking the job up into three separate spacecraft, an ascent module, a transfer vehicle and a descent stage would solve a whole host of problems. Quite apart from the obvious fact that if the transfer vehicle is designed to be reusable, then if it stays in space we skip the need for another launch to send it back into earth orbit again. Indeed, I’d go further and point out that direct flights to Mars using chemical rockets are extremely fuel inefficient (meaning our space craft ends up being mostly fuel tanks, as discussed), limiting the amount of cargo the ship can carry. There are alternative ways of getting there with a lower fuel burn, but they increase the time in space and thus exposure to radiation.

Using alternatives to chemical rockets (nuclear rockets, M2P2, solar thermal rockets, etc.) would however speed things up considerably and also have the advantage of cutting the fuel requirements down yet further (Isp’s of 900s or higher, twice that of LH2/LOx, at least three times better than what Musk is proposing).


Now you may say, am I not forgetting something, we don’t have nuclear engines, nor M2P2 (nor photon torpedoes!), so not a realistic proposal? Yes, but both Mars Direct and Elon Musk’s Mars plan also involve a an unproven element – that nuclear reactor to process the Martian atmosphere and create fuel. Then store that fuel in a cryogenic liquefied state for over a year on the surface of Mars. Has anyone built such a thing? How sure our we about Zubrin’s weight calculations? Has anyone built such a processing plant and sent it to Mars to check the concept will work? Yes the basic theory is sound on paper, but theory and practice are two different things. If I were Elon Musk I’d quit rocket and engine development and send a boiler plate test article to Mars ASAP and test the basic concept. If its not feasible he’ll be building in a massive weight penalty right from the start. To the point where this could be a potential show stopper.

This problem perhaps hints at a wider fundamental problem with both Musk and Mars Direct. It explains why NASA estimates for the cost of a Mars mission come in at hundreds of billions, while Musk/Zubrin/Mars One come in at a price of tens of Billions (or less!). To draw an analogy from mountaineering, NASA propose to climb the Martian mountain the same way they did with the Moon, what would sometimes be called the Mallory method in mountaineering circles. Here we lay siege” to the mountain. A large base camp is established (e.g. the NASA development centres) from where we make increasingly ambitious forays up the mountain. Based on the experience of these missions we eventually send a team of suitably equipped, acclimatised, experienced and well supported climbers, up to a high camp, from where they make an attempt on the summit.

By contrast what Zubrin and Musk propose is to climb the Martian mountain alpine style. This means taking the minimum of gear and climbing the mountain in one continuous push. This is a much more physically arduous task to perform, it requires a higher level of technical skill and it is much more risky (largely because your lines of retreat are limited if something goes wrong). Keep in mind there are several mountains worldwide that have never been climbed alpine style (and it would be suicidally stupid to even try!). By contrast the best analogy I can think of for Mars One is the fate (and cautionary tale) of Maurice Wilson, an eccentric amateur who tried to climb Everest unsupported in the 1920’s and ultimately descended into madness and died on the mountain.

But I digress, the bottom line is that to maximise ones chance of success on Mars, it would be sensible to conduct a serious of shakedown cruises and dress rehearsals first, much as happened during Apollo. Missions to the moon first, an extended space soak (e.g. to an asteroid, Mars or Venus flyby’s), test runs of the descent vehicle in the upper earth atmosphere (or on the moon) would gradually build up to the main event. Of course this would take longer and cost a lot more, but it would make the chances of success significantly higher. The reason why Aldrin and Armstrong didn’t pull the abort lever during those last few minutes prior to landing is because they had confidence in what they were doing. Confidence built up on the past missions they and their colleagues had performed.

Space central planning

Also there’s the obvious question why Mars? Musk say’s its in case some disaster renders earth uninhabitable. Well even any of the disasters he lists would still make the earth a more hospitable place to live than Mars. And there’s a whole host of issues I raised previously about human habitation of space which we’ve not looked into. But suffice to say there’s more than a few holes in this plan.

Perhaps the key myth we need to debunk here is the notion that you can build a space colonisation program without involving the government. It doesn’t help that many space cadets are rabid libertarians who see it as their way of breaking free from the shackles of government…..only some of them seem to think that said big government and its NASA’s resources and budget should now be turned over to Elon Musk. Ah, no! When did we vote to end democracy?

NASA I’m quite sure would like to work with anyone on Mars, they’ve incorporated parts of Robert Zubrin’s plans into their own mission designs, but their experts may decide to do things differently. They may want to go away and do some testing first. Almost certainly I suspect they’ll opt for their own SLS system for earth launch as well as stretch out the launch schedule, shrink the size and complexity of the main spacecraft (yet still bulk up the budget for its development) and generally downside the ambitions. They may offer elements of any future contracts to SpaceX (one assumes a competitive bidding process will be put in place), they made decide to go with someone else. The point is they know what they are doing, we’d be fools to ignore them.

But space cadets seem to want to skip this important process of technical review and democratic discussion. Going to Mars would be a big decision, not least because of the costs involved. That decision needs to be made in a democratic way, particularly if you are looking to taxpayers to bankroll it. Personally, I’d have no objection to a crewed Mars mission, so long as it was justified by well supported proposal of potential research outputs and it wasn’t overly expensive and its goals and objectives were realistic and achievable. However, there are plenty of people who won’t be willing to do so. And Musk and Mars one are proposing something more along the lines of colonisation of Mars and a blank cheque to go with that. Without the necessary justification and democratic mandate it would be insane to even try such a thing.

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Now everyone’s been Trumped



So its Trump, how can 60 million people be that dumb! Many are trying to put the spin on it, that it was working class Americans in rust belt states fed up with how they are treated in Washington that swung the election. Well no, the polling data (both before and after the election) shows the vast majority of Trump voters are middle class or upper class whites who generally have a better than average income. The majority of low income whites still voted for Hillary. Certainly some more of them than did vote for Trump than would normally be expected in an election, but in theory this was cancelled out (to some degree) by an increased level of turn out and voting for Hillary by ethnic minority voters.

Indeed its worth remembering that she carried the popular vote, Trump carried the key swing states by only a…

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Bigoted Britain



One of the more unsavoury aspects of the brexit vote is how the bigot brigade now feel they can throw their weight about. There’s been a worrying rise in racist and xenophobic incidents, up 14% nationally, but as high as 70% higher in some hot spots. A number of foreigner visitors (some only here as tourists) have reported all manner of stories of random abuse being shouted at them, eggs thrown at them, shop windows smashed or being attacked in a public park. Even Lily Allen has reported how she had abuse shouted at her by a cab driver who refused to accept her fare (she’d said something earlier in the week about how the UK should take in more refugees). And this is on the mild side. We have of course the recent murder of a Polish man (not being investigated as a hate crime) and of course…

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Space a sustainability solution – Part 2: Living on the high frontier


Figure 1: A future space colony?

In the previous post on this topic I outlined the general problems regarding space propulsion. In this article I’ll be looking at the problems of living and working in space, and the logistical challenges that this presents.

Motivations and costs

In the table below is a list of current metal and commodity prices.


Table 1: A list of key commodities which might be of interest to space miners in the future and their present day market price

To mine such resources from space would mean moving tens of thousands of tonnes of mining equipment to space. Its worth just looking at the spec’s for one or two of these machines and try to imagine how difficult and expensive it would be to re-locate such equipment to the moon or an asteroid. Even at launch costs in the order of a few hundred per kg it seems doubtful it would ever be economically possible to extract said resources and then send the ore back to earth (rare earth and precious metals being perhaps some of the few exceptions).


Figure 2: Lunar mining conceptional art [Source: NASA, 2013]

And speaking of which, recall that even after we’ve built our mine and extracted said ore, we would need to get the stuff back to earth. Some space cadets talk of building a giant “mass driver” to fling cargo into earth orbit, where cargo slugs are then de-orbited either by shuttle or retrofire and crash landed in the deserts. However both of these will still have some sort of cost associated with them. And even if said costs were small, say $100/kg and even if we could mine the stuff for less than its current mining cost on earth (which we can’t) commodity prices would have to get absurdly high before it would be economic to mine them from space.


Figure 3: A mass driver

What about He-3 I hear you say? shouldn’t we be mining the moon for that? Well actually no! That’s more of a fantasy and the last place you’d go to mine for it would be the moon.

A common and perhaps fatal mistake of many cornucopian’s is to assume that the price of commodities will just escalate upwards until some other lower grade of ore (or space mining) becomes economic (some will even go to such absurdities of suggesting that soil and water could be “mined”). However in reality the cheapest solution to escalating prices has always been conservation, using less, better recycling and switching to alternatives (or just making do without). Any time the oil price has gone up, cars which are more fuel efficient, or indeed cars that don’t need oil at all, have been churned out. Spikes in the price of rare earth metals (crucial for renewables) has resulted in conservation and more efficient use of said materials, as well as the development of alternatives.

So even if say, we began to run out of copper, its probable we’d sooner switch to Aluminium wire (or perhaps in the future graphene) and just make do, rather than go to the trouble an expense of a space mine. With the exception of certain niche markets (again rare earth metals) I can’t ever see space mining being economic. The one game changer would be if industries (i.e. factories) were to move into space (perhaps for environmental reasons), although again we’d face the problem of getting produce back to earth (could be viable for high value products, although not the cheap stuff we buy from China). Then there would be a demand for raw materials in space and it would make sense to source them locally. However for that to work we need to assess how easy (or hard) it would be to relocate large numbers of people to space to operate these mines and factories.

Space sustainability

At present it requires at least 10 kg’s of resupply to keep an astronaut alive on the ISS for a day. At present launch costs that’s a good half a million in resupply costs to keep a crew of 6 alive and functioning. Relocate all of that to the moon (which roughly triples the costs), increase the size of the crew to say a hundred (a reasonable estimate for a lunar mining colony), consider that building the ISS cost $100 billion, so something even bigger on the moon… get the message! Using current technology its not even remotely feasible. Even with launch costs down in the region of a thousand per kg, it still looks pricey (£5 million a day, not including crew rotation and construction costs).


Figure 4: The space life support process [Source NASA, ND]

If there’s any more potent symbol for what’s wrong with our society and our attitude to the environment, its astronauts on the ISS, living a throwaway life style needing regular flights to send them up supplies and deorbiting cargo ships to dispose of their waste. Clearly there is a need to develop a more sustainable life support system. And space agencies have been experimenting with creating viable self sustaining ecosystems in space, where plants absorb carbon dioxide, produce oxygen and grow food.

Photograph by John de Dios

Figure 5: The Biosphere 2 experiment [Source: University of Arizona, ND]

In the 1980’s the Biosphere experiments were carried out in which a group of 20 volunteers were placed in a hermetically sealed greenhouse for several months at a time to see if a viable biosphere could be created. It was found that the oxygen levels fell, as did food supplies, necessitating that air be pumped in an food from outside supplied. This lead many critics to label the experiments a failure and proof that any attempt at colonising a planet (or long range space flight) was doomed to failure. However this wasn’t the case. NASA did managed to drastically cut the resupply needs from what they would be on any space station. Also it did identify where the problems may lie. Further tests were somewhat more successful.

Certainly the Biosphere experiments did seem to indicate that any future space colony will need some level of resupply. However if they can get access to water (and thus oxygen and hydrogen) then this would cut down the level of resupply needed. Mars has abundant supplies of water frozen within its polar ice caps. The moon may have some small deposits of ice within permanently shadowed craters at the poles. The moons of Jupiter are almost entirely ice bound. So it does hint at a solution. However, resupply isn’t just food, water and air, but also spare parts and electronics. NASA is already toying with the idea of using 3D printing to aid in machine repair. So all in all, space colonies will need some level of resupply, but it can be cut down substantially from that demanded by the ISS. Indeed one could argue this the whole point of the ISS, to find those weak links in the supply chain.

No country for old men

Another problem is the health effects of long term exposure to low gravity and a heighten level of background radiation. Several long duration flights were carried out by astronauts on Mir and the ISS, which showed a astronaut can survive for several years in space. I actually once attended a talk from Mir astronauts and they did admit to having some difficulties on return (after over a year in space), but they quickly recovered over the following months. However, this was done in the comparatively calm and safe waters of LEO. What happen to any astronaut who ventured out beyond the earth’s magnetosphere?


Figure 6: Radiation dosages in space compared to earth based scenarios, note this is a log scale! [Source: JPL, 2013]

The consensus is that long duration missions to Mars or the Moon, lasting a few years should be possible. The astronaut will take a pretty hefty dose of radiation and suffer quite a bit of bone loss from microgravity. Keep in mind that even when he gets to his destination gravity isn’t nearly as strong as it is on earth (Mars its about 1/3rd earth’s gravity, the moon about 1/11th). The jury is out as to what’s the minimum level of gravity needed to stay healthy. So our returning astronaut may have to take some sort of hit to his or her long term health, but probably no worse than someone who smokes, drinks and doesn’t exercise enough.

However, the longer an astronaut stays, the worse its going to get. Insulating the colony to cut down on exposure is one solution, but at some point they will need to go outside and obviously they need to get there and back. Beyond a certain point the astronauts health will likely deteriorate to the point where they are more a hindrance than a help. They may fall victim to things like cancer, arthritis, leukaemia (which means you suddenly need to start shipping in a whole load of medical supplies). So its probably likely that in any space colony it will be necessary to rotate the entire crew out of the colony and pack them home to earth at regular intervals (exactly how regular is the question).


Figure 7: Burying future space habitats might make a lot of sense

This is an important point from a logistics point of view. It means that one way missions, such as those proposed by Mars One are little more than an expensive form of suicide. Quite apart from the astronaut’s health, a one way mission leaves no line of retreat. If a crew on a two way mission experience a medical emergency or an equipment failure, they can withdraw back to earth (either the entire crew or just those at risk). A one way mission crew have no way out, they either deal with the problem or die. If a resupply rocket crashes on take off (leaving them short of supplies), they’re dead. If their habitat fails they’re dead, if the only engineer/doctor on the mission falls down a crater they’re dead. Basically with a one way mission its a case of rolling the dice often enough and sooner or later you’ll end up with a TPK .

I recall some space cadet telling me how he planned to retire on Mars. Unfortunately, no way that’s ever going to happen. The last thing a Martian colony needs is a bunch of work shy geriatrics. With it costing the company or government running the colony tens of millions a day just to keep the lights on, they will try to keep the crew to a minimum and will want everybody working. Indeed they will no doubt make use of robotics to cut crew levels down to as low as possible. In much the same way that during Apollo program each astronaut had a pool of backroom boys running errands for him back on earth, each of our future space colonists could have the same. A small team of staff on earth who would sort out admin tasks, write programming code for him, run simulations, handle calls from the mother in law, etc. All he needs to do is focus on the tasks they can’t handle remotely, or the robotic drones can’t deal with. This could perhaps allow the numbers on a future space colony to be cut down to just a handful of people (such as in the movie Moon where there is literally just one man on the moon).

And no wee’ins neither!

Inevitably one has to ask the question, what happens when our astronauts start doing what humans have done through history and engage in “specific relating” (NASA terminology for astronauts humping) and the inevitable consequences that follow from that. Suffice to say they will be well advised to use birth control, because any women who get pregnant on a future space colony will likely be bundled into the first shuttle back to earth pretty quickly.


Figure 8: NASA conceptional art at its worst!

Above is probably one of the most scientifically inaccurate images ever produced by a NASA commissioned artist. Where to start. Well a space walk is pretty much the most dangerous thing an astronaut can do, what sort of deadbeat dad takes his infant son on a space walk? And how much would that space suit sized for kids cost?..not to mention the dozen others he’ll need as he grows older. And a child living on a space station would be exposed to low gravity and cosmic radiation levels at a critical point in his development…. and that assumes he wasn’t already born horribly deformed.

Those Russians I mentioned on Mir kept themselves busy by breeding chickens (well actually it was Quail, the idea was to create an protein rich food supply for future astronauts). They discovered that the birds suffered quite severe birth defects and a 60% mortality rate. They managed to correct this problem with a small centrifuge incubator, but they never quite solved the problem. And of course the problems would be much worse beyond LEO (due to heightened radiation exposure) and one assumes a chicken is a good deal less complicated than a human baby. Similar experiments were conducted with rats by NASA on the ISS, with research still ongoing.

And quite apart from the health risks to the child, or the mother since we’re talking about it, there’s the problem of having to have schools, maternity wards, a fully trained mid-wife, etc. And even inside a space colony can be a potentially dangerous environment. Recall that NASA started having kittens when they learnt of the Russian plan to fly space tourists to the ISS. A chain is only as strong as its weakest link and in an emergency any rugrat on a space colony is going to be a very weak link. Therefore space colonies will almost certainly be child free zones (were can I sign up!).

A stable of science fiction is that of future space colonies being the new Americas or Australia’s of the future. Of them eventually becoming sovereign states in their own right. However, given that the entire population of any future space colony will likely be transient labour, that doesn’t seem likely. In fact such colonies sound like the most awful grotty little mining town hellholes (the sort of middle of nowhere mining towns you’ll find in the Australian outback or Canadian Northern Territories). The sort of place people only travel to because some company’s paying them a shed load of cash to work there. They sound less like star trek and more like the space colony portrayed in the film “Outland.

Indeed speaking of Australia, its possible that space colonies might eventually become penal colonies, as portrayed in the Judge Dredd series (where Titan has become a penal colony for corrupt Judges). Where those sentenced to twenty years for questioning the size of the one true Donald’s….hands…..can cut his sentence down to five if he goes to work in the colonies (if he survives of course!). In the movie “Total Recall the colonists are fighting for independence from an oppressive corporation. In reality, they’ll be fighting for a seat on the next shuttle back to earth.


So by all accounts even if we do ever get around to building space colonies they ain’t going to be places people will flock too. Someone will go there yes (if you pay them enough!) but we’re not talking about a mass migration or anything. Which kind of suggests we cannot relocate a large chuck of the earth’s population off the planet. Is there anything we could do to create a place people would actually want to go to? One idea is to terraform planets, notably Mars (although there are other potential targets for terraforming), to create a living breathing atmosphere.


Figure 9: Terraforming Mars might take longer and be harder than many suppose [Source:, ND]

While there is no question we could heat up Mars (take a look a recent IPCC data and you’ll see we’ve been doing that to the earth!), but simply heating a planet up might not be enough. Just because a planet gets hotter doesn’t mean its going to magically sprout a oxygen rich atmosphere. This process took many millions of years on earth, one assumes it would still take a considerable period for any Martian atmosphere and the ecosystem it interacts with to evolve as well. And its far from proven whether we could control this terraforming process once its started (after all its not as if we’re in control of the process on earth, that’s precisely the problem with climate change!). And given that the planet’s original atmosphere (which was almost certainly not earthlike) was stripped away by the solar wind, what’s to stop that happening again?

One possible short cut is what’s known as Paraterraforming. This involves building a dome over some small area, e.g. a crater or one of those large valleys on Mars, pumping in air and starting to grow plants and develop a self sustaining ecosystem (as I mentioned that didn’t quite work out with the Biosphere, but I’m assuming we’d have corrected all the issues on earth before attempting this). So it represents a sort of “pay as you go” option of gradually terraforming small segments of a planet in stages. Incidentally, experiments have shown it is possible to grow plants in lunar soil, given suitable levels of fertiliser, water and protected from the cold. And we won’t be limited to just Mars, lunar craters could be terraformed, as could caverns built under the ice sheets of the moon’s of Jupiter.


Figure 10: Paraterraforming – life under the dome

However there are some things we can’t change. While our domed colony could be designed to limit radiation exposure levels (using a radiation absorbing aerogel to construct the dome, or indeed locating the entire colony under ground rather on the surface) any colonists will still take some level of elevated dosage (not least when they have to go outside or travel back to earth). We simply don’t know how much is too much. Also the gravity on such worlds is going to be much lower than earth gravity. It is, like I said, far from proven that its possible for humans to survive long term on a world with low gravity.


Figure 11: The interior of a future underground space colony? Note the guy with wings. In low gravity it would be possible for a human to fly like this

Rotating space colonies

One possibility is to build large rotating space stations, as proposed by Stanford Professor Gerard O’Neill back in the 1970’s. By spinning the entire colony, gravity can be generated. However there is the (not so) small matter of costs. Recall what we said about launch costs earlier. The ISS is costing at least $150 billion. We’re talking about lifting at least 10 million tons into orbit, against the roughly 420 tons of the ISS. Even with launch costs 1/100th that of the present level and a fairly aggressive experience curve to bring down manufacturing costs, you’re still talking about something with a price tag in the tens of trillions. Who is going to pay for that?


Figure 12: The interior of a rotating space colony

And what the hell are they all going to do up there?….aside from gradually soak up an elevated dose of radiation? I’ve heard some space cadets talk of setting up an offshore tax haven on such stations. This falls down for three rather obvious reasons A) No government in the world will ever recognise such a legal entity. There have been numerous attempts by libertarian types to set up new countries on oil rigs, ships or unoccupied Islands and every one of them has failed for this very reason. B) There are already plenty of nations on earth who offer these same services, who don’t require tens of trillions in initial start up costs and don’t need expensive resupply from earth and hence have lower running costs, so a non starter. C) Living on such a station would be extremely expensive (giving its likely high running costs) and is not without risks. This would immediately wipe out any tax savings.

A new breed of astronaut….literally!

One theory is to use genetic engineering to breed new species of humans adapted to low gravity and elevated radiation levels. But we have now drifted well into science fiction rather than science fact or even science possible (incidentally a good website on such speculations but with a “hard” science fiction view point is Orion’s Arm). We simply don’t know enough about genetics at present to even tell if any of that is even an option. But it does seem clear to me that we are unlikely to ever be able to relocate a significant proportion of earth’s current population to another world. Not now and not even in the distant future.


Figure 13: Future humans adapted to life in space….as envisaged by sci-fi authors [Source: Bernd Helfert &, 2000]

The reality is that we humans are evolved to live on earth. Other planets are basically outside our bodies design envelope. We can make extended stays, but that’s about it. Even if that new planet they’ve just discovered around Proxima centuri turned out to be a living breathing world (not unlike the planet Pandora in the movie Avatar), it would be an entirely alien world which we are not adapted too. Yes we’d probably send some scientists out there to pick up some rocks and study its eco-system, but that’s about it. It would be easier (and considerably cheaper) to try colonising Antarctica than Mars or any other planet.


Figure 14: Artist impression of the surface of the exo-planet Proxima Centauri b [Source: ESO, 2016]


All in all, I would argue that space does not offer a solution to our planet’s current sustainability issues. Yes over a long enough time period (hundreds of years!) its possible we’ll develop the technology needed and perhaps build some space colonies, but its unlikely to happen any time soon (by which I mean within the next 50-100 years). And we’re probably never going to be able to migrate millions off world. Running away from this world’s problems simply isn’t an option, we’ve nowhere to run too.

Does this mean space exploration is a waste of time? Absolutely not. Many technologies have come out of the space race, everything from carbon fibre, solar panels, fuel cells, microchips, even velcro and freeze dried food. And many of these technologies are crucial to developing a more sustainable world. One assumes this trend will continue. Any money spend on space exploration is (and has been) money well spent. And the sums spend on space exploration have, at present, not been particularly unreasonable (in the grand scheme of things). Although obviously a more aggressive campaign with higher levels of funding could change that, and we’d then have to question whether such a program represent value for money.

Therefore we do need to be realistic about what is achievable and what isn’t. And recognise the challenges and dangers such endeavours will have to overcome. For example: Is a crewed mission to Mars a worthy objective?

Well if the justification is to study the planet’s geology because this will tell us a lot about not just Martian geology but other worlds too (including some of those exoplanet’s we’re now finding). And also a Mars mission would try to establish whether or not there ever was life on Mars, and thus the probability of whether there might be life on those other worlds beyond this solar system which we’ve started finding. That sounds like a reasonable justification to me (although that does depend on the price). However if the justification is that we want to go to Mars to pave the way for near future colonisation and to start the terraforming (as Elon Musk appears to be saying), well now you’re just being silly. Go back to reading comic books!

However one conclusion to make is that like tackling climate change, space exploration requires an international effort. Voting for policies like brexit, or voting in divisive politicians like Trump is all but guaranteed to kill off space development long term.

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Space a sustainability solution? A critical review


Figure 1: Could space travel and eventual colonisation help solve some of the world’s environmental problems?

One could characterise the whole environmental debate, or the debate about issues like peak oil or overpopulation as all boiling down to one key issue – resources, or lack thereof. We live on a single planet, which has only a limited supply of materials and a limited area in which to live and grow food. And regardless of how much fossil fuels there are, the atmosphere has a limited capacity to absorb carbon dioxide and the natural world can only deal with so much environmental damage and habitat destruction before a collapse is a risk (with a knock on effect on food supplies).


Figure 2: We will likely face a series of resource crunches in the next few decades [Source: New Scientist, 2007]

Now we can debate the exact scale of these resources, if you believe the more optimistic voices on fossil fuels we could stretch supplies out a good deal longer than many assume. But they will start to run out sooner or later, almost certainly within this century. And keep in mind there’s some who say we’ve already hit the peak. And a growing population means a growing demand for resources which sooner or later we will not be able to meet. There’s a wide range of arguments on what is the sustainable population of earth, with estimates ranging from under 2 billion (if we all lived like Americans) to 24 billion (if we all lived like hippies!). But my point is that regardless of the number, there is a number, there is a limit. Its just a matter of finding it….hopefully without causing catastrophic environmental damage to the ecosystem in the process!

However, there is perhaps a loophole we are over looking – Space. If we could gain access to space that would change everything. Suddenly we’d have access to vast amounts of resources. For example a joint NASA and University of Arizona study took a seemingly average asteroid 3554 Amun and attempted to estimate how much resources we could extract from it. They concluded that it contained 30 times as much metal as the human race had mined throughout history, including iron, nickel, cobalt and platinum. Suffice to say one or two space mining colonies and any shortages of platinum or rare earth metals, in support of, say, fuel cell or solar panel production, would be a thing of the past.


Figure 3: Could space colonisation be the solution too our environmental problems? [DSI, 2013]

Moving earth’s more polluting industries into space would eliminate the threat they pose to the environment. And space could also provide power directly to the earth beamed down from giant orbiting solar power plants. So given the potential game changing nature of space colonisation, I think its important for us to assess how likely it is that we could colonise space.


Figure 4: Space based solar power satellites could beam power down to the earth from orbit 24 hrs a day [NASA conceptual art, ND]

In order to properly assess the possibility of space colonisation, we need to break the question down a bit. Firstly we are talking about “space colonisation” (going to Mars, for example, not to collect rock samples, but to stay) as opposed to “space exploration” (e.g. temporary crewed expeditions, robotic probes). Obviously exploration is a lot easier, indeed we’re already doing it. Colonisation is likely to be a lot harder and opens a whole can of worms in terms of problems.

Also we need to break the problem down into two broad areas – getting into space and an assessment of the technical problems and possible solutions therein. And secondly, the problems associated with living in space, or on other planets, on a long term basis. I’ll be tackling the first of these points below, looking at the habitation issue in a later post.

The cold equations of space flight

To achieve orbit around the earth you must accelerate a spacecraft to the seemingly unimaginable speed of about 25 times the speed of sound, about 8 km’s per second. If there’s one thing you need to know to understand the difficulties of achieving orbit its Tsiolkovsky rocket equation.


Figure 5: Tsiolkovsky rocket equation

The rocket equation states that to achieve a delta-v (i.e. a change in velocity) sufficient for orbit, typically about 9 to 10.2 km/s (varies depending on where you launch from, note this accounts for air resistance) will equal the exhaust velocity of the rocket times the natural log of the mass ratio (i.e. the fully loaded and fuelled mass on the launch pad divided by the dry empty mass of the rocket plus its payload). Do the maths and you’ll see that even using the best fuel available, with the highest specific impulse, which would be liquid hydrogen (LH2) and liquid oxygen (Lox) producing an exhaust velocity of 4.4 km/s, means that about 90% of the initial take off mass will be fuel.

This should make it obvious why rockets are built the way they are, in other words like giant gas tanks. Keep in mind that the remaining 10% of mass that isn’t fuel has to include everything else, the engines, the fuel tanks, the payload, recovery system (heat shield, parachutes), etc. Every gram of extra empty weight basically means several more grams of fuel must be carried. So the empty weight of the rocket has to be pared down to the bone. The truth is that rocket science isn’t that complicated (I pretty much just explained it in a few sentences above!). Rocket engineering on the other hand is the tricky bit. If rocket engineers had a motto it would be “yes it has to be exact”. Over-designing something means excess weight and no useful payload, under designing means it likely fails and gets blown to bits during launch. Naturally this explains why rocket parts are so expensive, we’re talking about applying a level of precision to parts exceeding that of the aviation industry. Then throwing away nearly the entire vehicle in the process of launch.


Figure 6: A Delta IV stage on its way to the pad [Source: NASA, 2007]

The rocket equation also explains the weight saving trick of staging. By splitting a rocket up part way through the launch, we can discard some of the useless dead weight of empty fuel tanks and unwanted engine capacity (since the rocket’s getting lighter, you don’t need as much thrust to keep going) as we climb, meaning we can deliver more payload. Staging also allows the rocket to switch between different propellants as it climbs.

Different rocket fuels have their own particular “sweet spots”. Solid boosters are useful as a first stage as they can provide a very high trust and are relatively cheap, so they can get the launch vehicle up off the pad. However, the Isp for solid rockets isn’t as good as with liquid bipropellants (like LH2/LOx), so normally we’d now switch to one of those. Historically no large LH2 burning engines existed (not the case anymore) and LH2 is somewhat expensive, so some rockets use Kerosene/LOx for the next stage (or for the first stage altogether), often followed by LH2/LOx for the intermediate stage that follows (as noted this supplies the best Isp possible). Once in orbit a space craft must manoeuvre and fire its engines on a periodic basis to achieve the desired orbit. Given that cryogenic fuels like LH2 or LOx would simply boil off over time, we now need some sort of storable propellant instead. Hydrazine is a common choice, either as a monopropellant, or in combination with an oxidiser of some sort. So by splitting up the rocket into stages allows us to use a range of different propellants in the same launch vehicle.

As the above should indicate, the end result is that any launch vehicle quickly becomes very large, complex and expensive. Which, as noted, is largely thrown away in the process of launch. As a result it currently costs tens of thousands of dollars to launch a single kilo of payload into orbit. Getting an astronaut up to the ISS costs tens of millions of dollars….and that doesn’t include the costs of supplying him when he’s up there (or building the ISS, the most expensive object in history). Its widely assumed that to allow space colonisation, we’d have to pull those launch costs to less than a thousand per kg, or possibly a few hundred per kg. Elon Musk recently suggested a figure of $200,000 per person. That’s a big ask, so what can be done to lower these costs?

Single Stage to Orbit

One proposal is to switch from expendable rockets to reusable launch vehicles, most notably an SSTO (single stage to orbit). The logic is that this would allow airliner like operations, no need to assemble stages first (which is also incidentally a risky process, NASA purposely keeps the number of staff in the giant VAB to a minimum in case of a catastrophic fire during launch preparations) and no throwing stages away either. How long do you think BA would stay in business if they had to throw away a 747 after every flight to America? This could allow more frequent operations with the same hardware and a smaller launch crew, with much of the hardware reused for hundreds of launches rather than just one, thus substantially lowering costs.


Figure 7: Some argue that single stage to orbit vehicles will bring down launch costs

However, developing a working SSTO is no easy task. Recall that roughly 90% of its take off mass will be fuel. The rest will consist of everything else, the fuel tanks, engines, guidance, crew (if any), life support, recovery system (e.g. extra fuel for a powered landing, parachutes or wings) and of course the heat shield. And that heat shield doesn’t just need to protect a small capsule but the entire launch vehicle. Keep in mind it was largely the cost of maintaining the shuttle’s heat shield that pushed its launch costs to double that of a conventional rocket.

In the 90’s and 00’s NASA attempted to develop two SSTO’s the Delta Clipper (from the DC-X prototype) and the Venture Star (X-33 prototype). As both vehicles developed and more and more systems were added, they either ended up seeing drastic reductions in payload, or the size (and cost) of the vehicle started to balloon in size. The last iteration of the Venturestar would have weighted in at 1,000 tons. Think about that for a minute, a vehicle 3 times the take off weight of a jumbo jet, just to get half a dozen astronauts up to the ISS. I’m sceptical if the servicing bill for such a behemoth would actually have worked out cheaper than current launch methods.


Figure 8: The X-33 (left) and DC-X (right) prototypes [Source: Justathinker, 2015]

On a wing and prayer

I’ve heard some argue that winged SSTO’s would get around the rocket equation because it doesn’t apply to aircraft. Well that’s not entirely true. Certainly wings generate lift, but they also generate drag. Now for most aircraft, cruising along at subsonic or low supersonic speeds, the benefits of lift outweight the problems caused by drag. However for a launch vehicle cruising at hypersonic speeds, its a little bit different. The drag would actually increase fuel consumption (potentially up to three fold more). This is why the aforementioned Venturestar went for a lifting body approach and vertical take off (minimising time in the atmosphere during launch), while the X-15 (which was air dropped from a carrier plane) went for short stubby wings. In both case the intention is to allow the vehicle to perform a glider landing but not aid with the boost and climb phase, by minimising drag during these phases.


Figure 9: Winged SSTO have long been a common element of science fiction, such as this example from the movie 2001

And speaking of which glider lands, as proposed in some SSTO studies, are not necessarily as safe as proponents claim. Landing such a large (and often quite delicate) aircraft at the sort of high speeds an SSTO would typically be travelling at, is a tricky manoeuvre. One or two X-15’s were written off in similar high speed landings. NASA actually fitted ejector seats to the shuttle for the first phase of its operations, for these very reasons. They only removed them because it was seen as unethical that the pilots would have a route of escape but the rest of the crew would not. Even so they developed an alternative bailout process for crew to ensure they could abandon ship if the mission commander decided a landing was too big a risk.

Taking the heat

Also while generating drag those wings (and indeed the entire spacecraft) will heat up…..alot! So the entire vehicle will have to be build to withstand such heat. You’ll also have to find a way of insulating the crew and electronics from the heat as well. On which point there are three approaches to heat shields. The ablative kind (used on expendable vehicles as it amounts to a form of sacrificial protection), the insulator/thermal soak variety (ceramic tiles that insulate the vehicle from heat, radiating it away by glowing red hot, come with all the disadvantages of ceramics, i.e. brittle, difficult to machine, expensive), or simply building the spacecraft out of metal or composite materials with a very high melting point.


Figure 10: The X-20, Dyna soar, a late 60’s space plane proposal during re-entry [Source: NASA, ND]

Given the problems with traditional heat shielding, a number of SSTO proposals have cited the latter of these approaches as their intended solution to the problem of heat shields. The trouble is that while the launch vehicle will survive re-entry, given that metals (and composites) are very poor insulators, everything inside it will be cooked to a well done crisp.

The only serious proposal for a space vehicle using a metal heat shield that ever came close to flying was the Dynasoar. And it needed an elaborate 3 stage cooling system to protect its single person crew and electronics from the heat of re-entry. It also needed to land on skids rather than wheels as there was no way any tire could survive re-entry heat intact (even inside the plane!). So there are some serious questions to be asked as to whether a number of these proposals are actually viable.

Airbreathing engines

Another proposal is to use air breathing engines for part of the journey, cutting down on oxidiser. For any spacecraft a vast proportion (typically 70-80% in fact) of that “fuel” at launch will be oxidser. So using the atmosphere as an oxidiser can produce a significant weight saving.

However air breathing engines tend to have a much worse thrust to weight ratio‘s. While the Saturn V’s F-1’s have a thrust to weight ratio of 100:1, a typical jet engine comes in at closer to 8:1, 5.4:1 for concorde’s engines,5.2:1 for the Mach 3 capable blackbird’s engines and about 2:1 for a scramjet. You’ll notice how the thrust to weight seems to get worse the faster an air breathing engine goes. This is not surprising because it needs to work at higher temperatures and endure higher working pressures, meaning it ends up getting heavier.


Figure 11: Specific Impulse by rocket engine type v’s Mach Number

The general assumption is that the weight saving benefits of carrying less oxidiser will be cancelled out by having to use heavier engines (and burn more fuel overcoming all that air resistance), quite apart from the fact that at some point you must switch to conventional rocket power (to get into space where there is no air) hauling a set of now useless air breathing engines all the way to orbit and back again.


Figure 12: Skylon and the Sabre engine system [Source: Metro News & Reaction Engines, 2008]

The British Skylon project proposes to get around a number of these issues by using an air breathing hybrid rocket engine called Sabre. Initial tests have been promising, they’ve demonstrated that they can potentially cool down the incoming airstream. However there are still a number of obstacles to overcome. By their own admission, the Sabre engine will need to generate a thrust to weight ratio of at least 14:1 (i.e. twice that of a normal subsonic engine!) to be effective. That’s a big ask and its far from proven that this is technically possible.

And recall that with past SSTO’s its not been the engines that have been the problem but the development of everything else that makes up the vehicle. Recall that the X-33 was cancelled because of the failure of a fuel tank during testing (well officially anyway, I think in truth NASA has by now given up on it and this was more of an excuse to kill off a project they could no longer afford to fund).

Two stages to orbit?

Indeed my main criticism of Skylon is why an SSTO? It would make sense to me to split Skylon in two. An air breathing lower stage that accelerates and raises the 2nd stage to a suitable speed and altitude, then separates and returns for a glider landing. The rocket powered 2nd stage then flies on to orbit. Yes this would mean facing the problem of mating these two stages back together again sometime. But I’m of the view that all the technical problems (and in-efficiencies) an SSTO presents us with do not outweigh the benefits of avoiding the job of bolting the two halves of the craft together again.

Keep in mind that the vast majority of space missions involve launching space probes and satellites, often to either higher orbits or beyond earth orbit. In such cases we have no desire to recover the 2nd stage (nor the payload). It seems to me to be rather foolish to risk a multi-billion dollar launch vehicle, flying all the way into orbit and back again, for a satellite worth a fraction of that.

Of course one stage or two stage, any reusable launcher still comes with the fundamental problem that my making the vehicle reusable you are increasing your initial capital costs building and developing it, adding in servicing costs between launches and decreasing the payload you could otherwise deliver, if it was non-reusable. The logic is that reusing the spacecraft with then cancel out these extra costs and the cost implications of the lower payload. However to date, the evidence doesn’t suggests this is feasible.

The big dumb booster approach

It is for all of these reasons that some argue that a reusable space launch vehicle, or an SSTO is a waste of time and would (like the shuttle) likely end up being more expensive to maintain than it is to just keep building conventional rocket stages. Instead they argue in favour of taking a cheap and nasty “Ryanair” style approach. Rockets are instead mass produced in large volumes on the cheap. A good example is the OTRAG concept which would have used large numbers of mass produced smaller self contained rocket stages bundled together to make larger launch vehicle stages.

The main down side of this approach is that launch vehicles like this would probably have a much higher rate of failure. If a rocket engine has, say a 1 in 200 chance of blowing up every time you start it up, the more engines on our rocket, the more dice we’re rolling, the more likely we’ll get a money shot. So probably not a good idea for crewed missions. Also the environmentalist in me has to shudder at the thought of 20 spent rocket stages ending up in the bottom of the ocean every time we launch a payload. Surely we’d need to send someone out to fish those spent stages out of the sea and recycle them? How much is that going to cost?

The not-so dumb booster

SpaceX have gone for a sort of hybrid approach somewhere between reusable launch vehicles and the BDB. On the one hand they are putting their faith in conventional rockets, which are mass produced using as many common components as possible. On the other hand they are also experimenting with reusable lower stages and upper crew modules. So far they’ve pulled down their launch costs to about half that of their nearest competitor, with further cuts expected once further refinements are added and larger launch vehicles are brought into service.


Figure 13: SpaceX have recently demonstrated the ability to recover their falcon 9 1st stage [Source: SpaceX, 2015]

However, its likely that there’s a floor to how low SpaceX can make space flight. And my suspicion is that this floor price will still be too high to allow space colonisation. Certainly it will make a number of the many things we’d like to do in space cheaper and thus more likely to go ahead. These include new space telescopes, space probes (notably to the moons of Jupiter) perhaps even crewed missions to Mars and the Moon. But colonisation (going to Mars or the Moon to stay) will require much lower costs to be viable (again Musk himself admits a figure of $200,000 would be necessary, about 1/20th the current cost).

Also rockets (in general, not just SpaceX) aren’t noted for their reliability. Most have a failure rate of about 1:12. So one has to question whether it would be feasible to take such odds with the lives of the many thousands you’d need to move into space for colonisation to happen. And its worth keeping in mind that those accidents will have legal consequences. Keep in mind that the space shuttle failure rate made it about as dangerous to fly into space on board it, as it was to fly combat missions over Europe in the 1940’s.

Beyond LEO

Up until now we’ve only discussed the difficulties of getting into orbit. However going further afield, to the moon or Mars for example, requires further engine burns. In terms of Delta-v’s while launching off the earth will be the largest single segment, going all the way to the lunar or Martian surface and back can add up an extra 50 – 100% onto that “delta-v budget”. And recall the “payload” for the earlier stages into orbit will be the fuel to perform these manoeuvres. Of the Saturn V’s take off weight of 2,300 tons the LEM, Apollo Crew modules and life support systems represented a mere 18 tons combined. Everything else (99.2%) was just fuel and engines.


Figure 14: Delta-V requirements for different missions. Note those in red indicate the possibility of an aerobrake, i.e. sometimes when there is no aerobrake option you’ll need to expend further fuel just slowing down!

Alternative propulsion options

Naturally this has led some to question whether it is practical to rely on “kick and coast” chemical rockets when moving beyond earth orbit. One idea would be to have a space station in orbit, where astronauts transfer from a launch vehicle to some sort of dedicated space vehicle. This would use engines that provided a much higher specific Impulse per kg of fuel. A solar thermal rocket (which uses large mirrors to superheat hydrogen gas) or a nuclear rocket engine (same idea but with a nuclear reactor doing the heating) can provide an exhaust velocity at least double that of a chemical rocket (9 km/s v’s a maximum of 4.4 km/s for chemical rockets). A VASIMR thruster could potentially provide an incredible 30-120 km/s.


Figure 15: Solar Thermal Rocket concept [Source: left – Hokkaido University (2010), right – JPL (2000)]

Another interesting idea is that of solar sails or magnetic sails. One such proposal is the M2P2 system. This uses a plasma generated by the spacecraft to inflate a magnetic bubble around the ship. This bubble then reacts with charged particles released by the sun and gets blown along like a tumbleweed bush in the wind. Such systems could offer 50 times the Isp of a conventional engine. A ship equipped with such a system could reach Jupiter in about a year (v’s the 5-7 years it currently takes). As an additional benefit, the magnetic field would serve to protect the crew from cosmic radiation.


Figure 16: Hitching a ride in a Magnetic bubble [Source: NASA, 2000]

You may enquire why I’ve not mentioned Ion thrusters (of Tie fighter fame) or Arcjets. Well because they are low thrust engines. They have a high Isp and a high exhaust velocity, but very low thrust (i.e. pushing power). It would take an Ion engined spacecraft about a year to reach the Moon. One assumes that any astronauts inside would need a good Netflix subscription and that any fuel savings would be cancelled out by the amount of Twinkie’s and Cheeto’s they’d go through over that year. More importantly you’d be increasing the time exposed to danger of the astronauts. The longer they spend in transit, the more likely it is that they’ll get fried by a solar flare.

Even putting such issues of safety aside, there are problems with a number of these alternative propulsion methods. Firstly, most of these ideas have never been flight tested. We have no idea how reliable they would be or what costs would be involved, as the technology is too immature to tell us. How long would it take to develop such propulsion methods? Your guess is as good as mine!

Going nuclear

Also a lot of these alternative propulsion methods nearly all rely on some sort of additional power source on board the ship. Solar power (either thermal or PV) is one possibility, but the quantities involved here means you’d need a very large array. So its possible some sort of nuclear reactor would be needed. Regular readers of this blog will know I’m somewhat skeptical of nuclear power, as I think its too expensive, comes with too much excess baggage and there are other far simpler alternatives available (renewables, or energy efficiency). In space however, I’d argue that it might be very difficult, if not impossible, to colonise space without the use of nuclear energy in some way shape or form. And powering spacecraft is just the start, I’m thinking about how to keep astronauts warm during those long lunar nights.


Figure 17: Nuclear Thermal Rocket Design [Source: The Time Machine Project, 2005]

However this is not to suggest all of the problems with nuclear energy magically disappears just because we are in space. Actually, they get worse. Our reactor will need to be very lightweight, which basically means a much more expensive design that the types preferred for power generation on earth. And a design that simple and easy to maintain (the astronauts may not be able to access it during flight). We’d need something that’s inherently safe (yet high performance) as there will be no mass budget to take along triple redundancy backups or multiple layers of containment. Keep in mind that if a nuclear power plant goes into meltdown on earth, we can just evacuate everyone (for 100,000 years!). The astronauts will essentially be strapped onto the top of a melting down reactor, they’ll have nowhere to go in an emergency. Stephen Baxter, in his excellent “hard” sci-fi book “Voyage” considers such a scenario…and the PR disaster that follows!


Figure 18: A NASA contractor inspects the RTG power sources for the Cassini spacecraft prior to launch [Source: NASA, 1997]

Space agencies have used RTG’s (essentially a lump of plutonium with a heatsink and a Seeback effect power generator attached) to power deep space probes or Martian rovers, but they’ve never been used as the primary means of power/propulsion on a manned space mission. Nor have we ever launched a nuclear reactor into space. Back in the 1970’s NASA did attempt to develop just such a nuclear engine, in a programme called NERVA. While many technical aspects of the project were proven to be sound, it was ultimately cancelled during the testing phase. It would take further design and development to confirm the viability of such a design.


Figure 19: NASA’s NERVA nuclear rocket engine undergoes testing in the 1960’s [Source: NASA historic image]

And then there’s the problem of launching our nuke into orbit. Again this brings us back to our choice of launch vehicle. Those with beach front property down range from the launch site might not be terribly keen on a 1 in 12 gamble every time NASA wants to launch a Mars mission. And what happens if our reactor accidentally falls back to earth after its been used? That’s happened with RTG’s before, but not a large nuclear reactor. Space cynic Jeffrey Bell discusses the likely consequences of such an accidentand the PR disaster that follows!

Hence there’s a lot of political implications (as if the technical problems we’re enough) for using nuclear power in space and they would need to be addressed first. Simply telling people there, there, we know best, we work for NASA and smoke pipes ain’t going to get you very far.


All in all we can see that the obstacles to space colonisation are indeed numerous. There are possible solutions and research is ongoing on some of those as we speak. However I find it doubtful that space colonisation is going to happen any time soon. We are probably going to face some sort of a crisis (energy or environmental) within the next 30-50 years, unless there’s a major change in policy (of course there’s some who’d say we’re already at crunch point now). And its unlikely all of these technical hurdles could be overcome within that time frame.

Not least because we’ve only discussed up until now the technical problems of getting into space. Even if all these propulsion problems could be solved there are a further range of problems which come with trying to live in space, something I will discuss in the 2nd part of this article.

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