Personal – Mars One School Visit Q&A

I wanted to share something that happens when you regularly visit schools and talk about something awesome like exploring Mars: the job isn’t just answering questions for kids at the school on the day, it also usually means answering questions for kids (and adults) who couldn’t make it or didn’t have time to ask their question on the day too!

After my run of school visits recently one of the teachers at a school I spoke at was bombarded by their 9-10 year olds who didn’t get a chance to ask everything they were curious about, so when I made my usual offer to answer via email they took me up on it. For those of you curious about what sorts of questions I usually get from students and the answers I give them, read on!


Is part of your job to look for any precious stones on Mars? We won’t be looking specifically for precious stones on Mars, but we will definitely spend a LOT of time looking at the rocks on Mars! Studying the rocks on Mars can tell us more about Mars what it might have been like in the past and where the water is. We’ll also have to study the rocks on Mars if we ever want to try to find alien life there, because if we’re going to find fossils or even living alien microbes or bacteria, they’ll be living in or on the rocks!

How do you eat with your helmet on? Inside the habitat you don’t need a spacesuit, so you can just wear normal clothes and eat/drink normally. When you go out onto the surface however you need to wear the bulky spacesuit with the helmet for up to 7 hours at a time. There’s a bag of water inside the spacesuit with a straw next to the astronaut’s head they can sip from, and there’s is a pouch below their chin they can reach down with their teeth to pull up a fruit & cereal bar to eat if they get hungry. The water is pretty easy, but the fruit & cereal bar is really awkward, plus they have to eat all of it straight away so that they don’t have crumbs floating around inside their helmet! Eating with a spacesuit on is really difficult, so most astronauts eat before they put the spacesuit on to go outside.

What does the impact feel like when you land the space craft? Depending on the spacecraft it can be either really gentle like a passenger plane landing, or it can be incredibly jarring and potentially break your back! The space shuttles landed just like a plane, and even though they were going much faster than a jet when they touched down, they could still be very gentle. A Soyuz capsule however fires a single rocket blast a few meters above the ground to make an impact that could kill you a tiny bit gentler! The spacecraft that will land us on Mars will almost certainly use rockets for a lot longer to land much gentler than the Soyuz, but not as gentle as landing like a plane with a space shuttle.

Soyuz landing with retrorockets firing (middle) and impact (right)

What happens if you stay on the surface of Mars longer than one hour? There’s no problem staying on the surface of Mars longer than an hour, and we’ll regularly need to go outside for a lot longer than an hour to make repairs and explore. At the moment though our spacesuits don’t provide any extra protection from the radiation on the surface of Mars, so if we went outside for more than an hour every day then we’d be exposed to too much radiation. We might go outside for 7 hours one day, but then we might stay inside for the rest of the week! It’s all about making sure you don’t go out on the surface more than an hour per day on average, because if we do we’ll increase our risk of cancer and other radiation illnesses beyond the approved limit.

How will you grow fruit and veggies with all the gases in the Mars environment? A friend of mine has been researching exactly what mix of gas would be best for growing fruit and veggies on Mars! The atmosphere on Mars is too thin to grow things outside of a sealed habitat, but she found that if we took the atmosphere on Mars and pressurised it, then added a little bit more oxygen (made by extracting water from the soil then splitting it into hydrogen and oxygen) then you would have the perfect mix of gas for growing plants! Humans couldn’t breathe it because there would be way too much carbon dioxide, but plants would flourish.

What type of plants grow on Mars? No plants yet, but once we start landing greenhouses and habitats there we’ll be able to start! So far Mars One has tested growing radishes, peas, rye and tomatoes and shown that they are completely safe to eat when grown in soil with the same soil with a mix of minerals and heavy metals as we’ve detected on Mars. There are 6 other crops that we know will grow in that same type of soil, but they haven’t finished testing to see if the heavy metals have been absorbed by the plants yet.

The first harvested tomatoes from Mars soil simulant.

Have you discovered any space junk on Mars yet? Depending on who you ask, there’s a few things on Mars some people might call junk that others call “historical sites”! We know the Beagle 2 probe landed on Mars safely in 2003, but it never deployed all it’s panels so it eventually ran out of power and is sitting dead on the surface of Mars. There are rovers like Sojourner and Spirit that have now failed too. Plus there’s stuff on Mars that really is junk – the heat shield that protected the Curiosity rover as it traveled through Mars’s atmosphere was dumped mid-air so that the skycrane could deliver the rover to the surface, plus the skycrane itself crash landed somewhere on Mars afterwards too! There’s a few bits of human junk on Mars, but not a lot – it’s pretty tough to get things there, so we want everything we send to Mars to be as useful as possible.

How can you live without your family? Lots of people in history have had to say goodbye to their friends and family in order to explore places that people have never been before. Most explorers plan to come back again, but millions of people said goodbye to their families forever when they immigrated from places like England to Australia, or from Ireland to the USA. Those families would know that they were starting a new life somewhere else, and while they would miss them they knew that life itself is a one-way mission.

How do you wash your clothes on Mars? We’ll have to be very careful to conserve water on Mars, plus the reduced gravity on Mars means we won’t sweat into our clothes as much as we do on Earth so we probably won’t need to wash our clothes as regularly. There’s still some gravity though, so we’ll either wash by hand in a tub of water or if we’re really lucky someone might design a washing machine that works in the reduced gravity on Mars.

How do you play sport on Mars? We might not be able to play lots of team sports on Mars, and if we do it’ll be really difficult in our spacesuits outside! People have done it though – in 1971 Alan Shepherd played golf on the Moon after sneaking a golf club and some balls onto Apollo 14 before the launch! Mostly we’ll stay fit and healthy by using equipment like you’d see in a gym, but designed to work on Mars.

How do you get materials to Mars to grow crops? The soil on Mars (called “regolith”) has almost everything you need to grow plants, except it doesn’t have any living bacteria or microbes to support the plants. So one option shown in the movie “The Martian” is to use the regolith along with waste from the toilet (after it’s been treated) to make soil that plants will grow in!

What type of safety equipment would you use most of? We’ll use a lot of different safety equipment in all sorts of different ways on Mars, but one of the most important is something as simple as a cable to hook your spacesuit onto! In space it’s VERY important to tether yourself during a spacewalk because you could float away if you aren’t hooked on to the spacecraft, but on Mars hooking yourself onto a cable between you habitat and a rover could mean the difference between finding the habitat in the dark after a long spacewalk, and getting lost in the dark!

Are you hoping to find aliens on Mars? I think we’ll find aliens on Mars, but they won’t be little green men or Marvin the Martian – they’ll be bacteria, microbes, and maybe something like a tardigrade. Tardigrades are these tiny little creatures smaller than a pinhead that are incredibly tough: surviving radiation, freezing cold, blistering heat, and even the vacuum of space! We know that Mars had water and was more habitable than Earth a few billion years ago, so it’s even possible that life started on Mars, hitched a ride to Earth on a meteorite, and we’re actually all descended from Martians!

Tardigrade (Approx. 1mm long)

How do you drink fluid on Mars? You can drink on Mars just the same as on Earth, except water will pour out nearly 3 times slower than it does on Earth. It means that for things like showers, you might get really big droplets instead of the ones you’re used to from your shower at home, but drinking will be just the same.

Will you have a car on Mars? The first people on Mars won’t have a car, but when they first land on Mars they might sit on a rover and have it take them from where they landed to the habitat that the rovers have setup for them. Sending a car or truck for Mars means lots of weigh, and we are only sending just what we need when we first go. In the future though we will definitely want someone to bring a car or big rover we can live inside so we can explore much further from the habitat than we can just walking or sitting on a normal rover.

How high can you jump on Mars? Mars has 38% of Earth’s gravity, so you provided your legs muscles are still as strong on Mars as they were on Earth, you’d be able to jump nearly 3 times higher!

Will you get sick of eating the same food all the time? We have to be really careful about making sure there is lots of variety in our food, because people DO get sick of eating the same thing all the time and it’s important for people’s mood. The very first mission NASA carried out at their Mars simulation mission in Hawaii was to see how they could add variety to the meals while people were living in a white dome with only limited food selections. For 4 months the people inside needed to work out how to use the same few ingredients they had to make all sorts of new dishes. So learning to be creative and take what you have and turn it into something new and different is one of the most important skills a Mars colonist will need to have.

Hi-SEAS in Hawaii

Space – Getting To Mars Part 3: Propulsion

We kicked off my series on “Getting to Mars” last time with a look at Orbital Mechanics – showing that the physics of getting from one planet to another can be mostly explained with a stapler, a pen, and Kristen Wiig looking unimpressed. This time we’re looking at the propulsion systems that we’ll use to get to Mars.

Of course because every armchair expert has their own pet propulsion project they think is critical to the future of space exploration, this is probably the article I’ll have to delete the most hate-mail for. That’s right – I don’t even read your unsolicited and poorly-spelled bullshit before deleting it, but thank you for reading all of mine! And if you haven’t already figured it out this is also the article you’re probably going to get me at my snarkiest, because there are three phrases I hear on a fairly regular basis that genuinely get under my skin and strangely all three are connected in some way to spacecraft propulsion…

#1 “Space is hard” – The lame catch-cry of everyone that’s just watched a spacecraft disintegrate in a “rapid unscheduled disassembly“. Don’t whinge that space is “hard” – find the cause of the problem and learn from it. Space isn’t hard, it’s just unforgiving of screw-ups. Screw-ups like when someone puts in a gyroscope upside down on a US$1.3 billion rocket launch, or when someone else loses a Mars probe because it was built by the world’s biggest aerospace contractors in the only country besides Liberia & Myanmar still fighting the Metric system.

#2 “It’s not rocket science” – The sarcastic accusation that something you’re struggling with isn’t really that difficult. You know, instead of helping you, someone will suggest you’re an idiot. Here’s something for all of you unhelpful jerks: Rocket science is not difficult. Rocket science can be explained with literally ONE equation (aptly called the “Rocket Equation”) that’s not even remotely complex. Ready for it?
Where \Delta v\ is the change in the spacecraft’s velocity, v_{\text{e}} is how fast things are being shoved out the back of your spacecraft (eg. the rocket exhaust), and you multiply that by the natural logarithm (\ln ) of your spacecraft’s initial mass (m_{0}) over it’s final mass (m_{f}). You can also express the same equation in terms of specific impulse, but if it’s all feeling too complex just remember you go faster if you throw bits of your spaceship out the back really fast to make it lighter.

Rocket science is not difficult, however rocket engineering is ludicrously complex and exceptionally challenging*. So next time you decide to be an obnoxious and holier-than-thou wanker to someone trying to do something they’re struggling with, how about at least getting the terminology right?

*For why I still refuse to say rocket engineering is “hard”, see point 1 above

#3 “We need to develop better solar electric propulsion to get to Mars” – I’ll get to why you’re what’s wrong with the space industry a little later, but for now lets just say you’re a piece of shit and I can prove it mathematically.

Spacecraft propulsion can be broken down into two big categories: Thermodynamic (using heat to move gas) and Electrodynamic (using electricity/magnetism to move gas).

Thermodynamic

This category is mostly the kind of spacecraft propulsion everyone is familiar with: rockets. Absolutely no one is doubting that rockets look super cool. They’re also dangerous, wasteful, noisy, and prone to going boom because of the most tiny and obscure things… like super-chilled liquid oxygen turning solid on your carbon-fiber wrapped helium tanks.

Rockets are also ridiculously expensive and absurdly inefficient at getting things to space. The Saturn V that launched men to the Moon* weighed nearly 3 million kilos on launch, but only 5,560kg of that was left by the time the Command Module splashed down in the ocean. To put it in context, 0.185% of the original rocket’s mass came back to Earth and the other 2,964,440kg was either burnt as fuel, dumped in the ocean/space, or left on the Moon. Considering each Saturn V launch cost about US$1.16 billion in 2016 figures, that’s a whole lot of specialised and expensive stuff to be just throwing away.
* Don’t even start with me Moon Hoaxers – I will destroy you

I’d talk about how NASA’s “Space Launch System” is supposed to (eventually) be more powerful than Saturn V… buuuuuuuut since SLS & the Orion capsule are basically the worst parts of the Bush-era Constellation program that have already cost US$18 billion and are now projected to reach US$35 billion in 2025, at this point it really looks like it’s just a pork-barreling jobs program for a bundle of US Senators through the old conservative aerospace manufacturers. A jobs program which is also takes funding away from real exploration opportunities (like the underfunded Commercial Crew Program) to build a rocket that’s going anywhere. #NotEvenSorry

I currently have a bet with a fellow space geek about SLS: I’m convinced it will be cancelled before it ever flies, whereas she thinks it’ll fly once before it’s cancelled. The loser has to buy the other a ticket to Mars aboard this…

Did you see that gigantic rocket flying itself back to the launch pad to refuel and launch again? That’s SpaceX’s “Interplantary Transport System”, and once it’s up and running in the 2020’s there will be several of these taking 100 to 200 people to Mars every few years for about US$200,000 each – return trip included. They can afford to talk about sending people to Mars and back for less than the median cost of a house in the US (or 1/4 of a house in Sydney) because they’re not dumping most of their rockets into the ocean every time they launch – they’re landing them, refueling them, and launching them again. Building better rockets and not throwing most of them away after a launch means the cost of getting stuff to orbit has decreased dramatically in recent years.

We’ve never used rockets for their efficiency though – we use them because they produce a huge amount of thrust. If you have to get something from the ground into Low-Earth Orbit, it needs to push through the air with enough raw power and velocity to break free of the atmosphere and start falling around the Earth with enough velocity not to hit it again. Right now the only thing we’ve got that can push hard and fast enough to reach orbit is rockets, and no matter whatever weird propulsion system other folks might be dreaming about this is also the only way we’re going to get to Mars in the next 15-20 years*.

*Bring it on Solar Electric Propulsion people – I’ve got your number at the end of this article.

That’s not to say all rockets are the same though – we’ve got all sorts of different ways of making things go boom to get somewhere fast:

Solid Rockets – Basically really big and complex versions of the little gunpowder rocket engines you can buy at a hobby store. They’re cheap, powerful, and easy to make – perfect for launching things like cargo and probes into space.

It’s probably not a great idea to use solid rocket boosters on anything carrying people though – once you light a solid rocket you can’t stop it burning if something goes wrong… like when one on the space shuttle burned through an o-ring and into a 760,000kg tank fuel of rocket fuel, which then exploded and killed seven astronauts. But NASA is planning to use solid rocket boosters again with the crewed SLS (test fire pictured above). So, you know… YOLO.

Liquid Rockets – Pumping flammable liquids into a chamber and having them explode in a specific direction. While the Chinese were the first to get serious about solid rockets back in the 1200’s, it wasn’t until the 1900’s that a guy called Robert Goddard started to set fire to liquids to push rockets around. Unfortunately the US’s scientific community and the New York Times just made fun of him for suggesting rockets could work in space.

Correction the New York Times published 3 days before Apollo 11 launched (on liquid rockets) to the Moon… and 24 years after Goddard had died.

Fortunately some people payed attention to Goddard’s research into liquid rockets. Unfortunately those people were also the Nazis, who then used that research to bomb Europe with these:

Liquid rocket engines are way more complex than solid rocket engines essentially because the fuel is sloshing around and needs to be pressurised through tanks & fuel lines for them to keep flying. Going back to my earlier “rocket science is easy, but rocket engineering is hard” – the national security restrictions imposed by each country on who can work on their rocket technology often has little to do with the rocket itself, and is almost entirely about protecting the technology behind the turbopumps that push the fuel and oxidiser at high speed & pressure into the engine bell.

Liquid rockets generally get broken down into two further categories depending on their fuel too. Bipropellants are what you see in a usual rocket launch where an oxidiser (usually liquid oxygen) and a fuel (kerosene, liquid hydrogen, methane, ect) burn to produce thrust. Monopropellant is a single liquid that ignites when it touches a catalyst, and is often used once you’re in space to turn your spacecraft around or give it a gentle push. It’s also usually made of hideously toxic, carcinogenic and explosive liquids like Hydrazine, that apparently smells like fruity-ammonia if you live long enough to tell someone.

Hybrid Rockets – A surreal mix of a solid and liquid rocket. The most obvious and well-known example of a hybrid rocket powers this:

Virgin Galactic’s Spaceship Two

Hybrid engines have a liquid/gas oxidiser that runs through channels in the solid fuel to burn it. They avoid the complexity of liquid rocket engines, and unlike a solid rocket you can stop them once they’re lit by cutting off the oxidiser supply. The downsides are they’re not as efficient as solid or liquid rockets, and most of them are filthy polluters. The fuel going into hybrid engine in Spaceship Two has been changed a lot, but it’s usually nitrous oxide burning rubber. So pumping soot directly into the upper atmosphere isn’t exactly fantastic for things like Global Warming…

Nuclear Propulsion – Launching tonnes of hot, radioactive material into space because it’s really good at getting you places fast… provided it doesn’t explode on the way.

Now I’m only including this because it is a form of thermodynamic propulsion, people have talked about for more than 60 years, folks like NASA & the Soviets have designed entire working systems around it… and even at it’s absolute safest it’s still fairly insane.

Nuclear rockets are outrageously powerful – even the most basic designs are twice as powerful as what’s possible with a chemical rocket. There are dozens of different (theoretical) varieties, however only two have ever been developed properly: NASA’s NERVA and the Soviet Union’s RD-0410. NASA actually had the closed-cycle NERVA XE flight ready and deemed suitable for a Mars mission in 1969, right before NASA’s funding was cut because it was clear the US was going to win the race to the Moon. Both the NASA and Soviet systems still involved using a flying nuclear reactor to super-heat hydrogen in space, however they were designed to be comparatively safe “closed cycle” systems.

I say comparatively, because you have to compare it to the other crazy shit other people were suggesting in the 1960’s. Fun things like “open cycles” designs that used weapons-grade radioactive material and deliberately spewed out clouds of radioactive exhaust.

See the bit saying “Uranium 235 T~55,000 K” leading to an open nozzle? Because fuck everyone else on the planet, right?

Then there’s the folks who designed Project Orion, who clearly felt the only thing better than using a nuclear reactor in space would be to use actual nuclear weapons. Project Orion was about literally firing a nuclear weapon behind your spaceship to propel it in the other direction: for anyone who’s ever played Quake or Team Fortress 2 this is basically a rocket-jump but with a nuke.

We’re not talking about just one nuke either: the idea was to have one going off every second, and some of the interstellar designs called for a spacecraft 20km long that carried 300,000,000 1-Megaton nuclear weapons, or “pulse units” as they were so eloquently renamed. Strangely enough Project Orion pretty much ended when most of the world signed the “Treaty Banning Nuclear Weapon Tests in the Atmosphere, in Outer Space and Under Water” (aka the Partial Nuclear Test Ban Treaty) in 1963.

The fever dreams of Dr Strangelove

Chances are we’ll need some sort of nuclear propulsion in the future to take humans beyond Mars though. Jupiter barely gets 4% of the sunlight the Earth does, so the diminishing light from the Sun makes solar power a lot less viable. It’d also be a great way to reduce the nuclear stockpiles we have, and there’s even some semi-reasonable arguments for taking small nuclear power plants to provide electricity to a colony on Mars – the big issues are obviously what do you do with the waste and what if something breaks?

Nuclear propulsion isn’t completely insane… but do we need to take the risk, when we can get to Mars just fine using conventional chemical rockets? No. 

Do you know what else we don’t need to get to Mars? Solar Bullshit Electric Fucking Propulsion.

Electrodynamic

Maybe you’ve heard on the news about some crazy space propulsion system that uses lasers, ions, or something else that sounds really complex and weird. Chances are it’s either a solar sail (which are slow but cool in their own “Star-Surfing with Sagan” kind of way) or you’ve heard about some variant of an ion drive (which are also slow but cool in their own “Star Trekking with William Shatner” kind of way too).

Ion drives are not some far flung science-fiction fantasy though: Harold Kaufmann built the first ion thruster in 1959, the Russians launched their own variant (known as a Hall Effect Thruster) on a satellite in 1971, and almost all modern communication satellites use some form of ion drive for “station-keeping” – correcting for variations in Earth’s gravity to maintain a highly precise “geo-stationary” orbit.

Essentially ion drives use electric fields to accelerate a gas (usually Xenon) out an exhaust at incredibly high velocities to produce a tiny thrust. The high exit velocity (aka “Specific Impulse”) means ion drives are insanely efficient and capable of reaching much higher maximum velocities than any rocket ever could, and there’s been some really exciting improvements… but because ion drives only throw out only a tiny bit of gas (eg. roughly the same amount of force you feel blowing on the back of your hand) they’re also incredibly slow to accelerate up to those high velocities.

How slow? NASA’s Dawn mission has three Xenon ion thrusters capable of 90mN of thrust (about the same force as the weight of a postage stamp) that can accelerate the probe from 0 to 100km/hr over four days.

Ion drives absolutely have their place, but no matter what bullshit spin some of the old aerospace players might try to pull that place is not getting people to Mars. Ion drives are improving, but unless VASIMR unexpectedly gets a demo flight and proves it actually works electrodynamic propulsion simply won’t be powerful enough to shorten the trip to Mars for humans any time in the next few decades. Especially if you’re only using solar power.

Improved ion drives that run on solar power will be really useful however for… getting communication satellites from Low-Earth Orbit into a Geo-stationary orbit.

Here’s a fun fact: the global satellite communication industry generates over US$200 billion in revenue each year, and makes up nearly 2/3’s of the entire space industry. Reaching Low-Earth Orbit (160km to 2000km altitude) with a rocket is relatively simple, however getting to Geo-stationary orbit (~36,000km and where almost all large communication satellites need to be placed) is much harder, requires far greater velocities, and usually needs an additional stage on the rocket. This extra velocity and additional staging brings greater risks of things going wrong, so naturally launching something to such a high orbit is also a lot more expensive.

So if telecommunication companies can launch new satellites to a much cheaper Low-Earth Orbit and then use solar powered ion drives (aka “Solar Electric Propulsion” aka “The bane of my existence”) to slowly shift new satellites up to geo-synchronous orbit over several months, they’ll save literally billions in launch costs alone.

Are you bored by this yet?  

No shit – the satellite communication industry is boring, but it’s also really big money. Do you know what is not boring, but also means risking lives for something that won’t make anywhere near as much money? SENDING PEOPLE TO MARS.

Which is why there’s a huge amount of money and research going into solar electric propulsion at the moment, and why I roll my eyes obnoxiously at everyone who tells me it’ll “help with NASA’s #JourneyToMars”. Because they either don’t understand how weak solar electric propulsion currently is, or they’re trying to bullshit me and others into believing a technology being developed to reduce the cost of deploying communication satellites around Earth will somehow get me to Mars.

I’m happy to be proven wrong on all of this, and I’m certain in the far future we’ll use ion drives to zip between Earth and Mars. I’m even sure some of them will even use solar power. They’ve been trying since 1971, but maybe Ad Astra will finally get somewhere with VASIMR afterall. Maybe the EM Drive will be completely validated and change everything. But don’t tell me we to need to pour billions more into solar electric propulsion research to get to Mars – chemical rockets have been getting things there just fine for decades.

In the meantime, Mars One was founded with the express purpose of permanently colonising Mars, and SpaceX was founded with the express purpose of establishing a sustained human presence on Mars too. Do you see either of them talking about needing further research into solar electric propulsion?
No? Just using conventional liquid rockets you say?

Funny that…

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Space – Getting To Mars [Part 2: Orbital Mechanics] or: How I Learned To Stop Worrying and Love Gravity

There’s a common misconception among the general public that physics is boring, yet nothing could be further from the truth. As a physicist I can say with confidence physics is awesome, it’s just physics teachers that are boring. I hesitate to say all physics teachers are boring, because I’ve met a few really exceptional ones… but there’s also been plenty of others who some how manage to suck all the colour and joy out of the incredible relationships that govern our universe. So with this in mind we’re going to tackle arguably one of the most abstract, mathematically complex, and potentially boring concepts in Newtonian physics – Orbital Mechanics – and we’re going to make it awesome instead.

Also I don’t mean in that fake-smiling “YAY!!! ISN’T THIS FUN KIDS?!” way where you’re desperately trying to convince yourself and others that your entire life’s work means something, while your soul slowly crumples inside as you fight the creeping existential dread that the universe is unloving and ambivalent to your existence and everything you do… I mean in a “Holy crap the universe is ridiculous, awful and weird, and I need to know more!” equation & jargon-free kind of way to explain how we’ll get to Mars.

Which I think we can all agree is a lot more fun than reading Nietzsche and embracing nihilism over a cup of tea.

Firstly some basics. If you want to go anywhere in space, you either need to a) increase your spacecraft’s velocity using a rocket or other propulsion system (we’ll cover propulsion in the next article) for a little to increase the size of your orbit and coasting through space as gravity to pulls you around on a curved path, b) have a ludicrously powerful propulsion system to brute force a straight line to wherever you want to go, or c) travel at 88mph and use 1.21 Gigawatts of energy to tear a hole through the fabric of space-time and pop out wherever/whenever you like.

Because we don’t yet have anything even remotely powerful enough to brute force a straight line through space, and neither Doc Brown or Sam Neill have been opening any portals to hell recently, that leaves firing a rocket for a bit to increase the size of our orbit and letting gravity do the rest of the work. The most fuel-efficient way to do this is called a “Hohmann Transfer”, where you increase your velocity just enough to reach where you’re going. When you’re trying to get from Earth to Mars that means burning your rockets when your spaceship is closest to Earth (to get the most out of the rocket thrust) and after coasting for 8.5 months you arrive at Mars at the slowest point of your new orbit.

Burn your rocket when you’re travelling fastest at #1 (Earth), slow down as you travel along the yellow line, arrive at #3 (Mars) when you’re at the slowest point of the new orbit

But “fuel-efficient” is slow and boring – the space exploration equivalent of having sex while listening to Enya. It’s fine if you don’t have anything better to do with your afternoon – or if you want to launch cargo to Mars that can take 8.5 months to get there – but the longer you spend in deep space the more cosmic radiation (and Enya) you’re being exposed to. Humans also need food and water and oxygen and a bunch of other nonsense robots and cargo don’t, so Hohmann transfers aren’t ideal for sending humans to Mars unless you really hate them.

Getting to Mars in less than the 8.5 months means we have to leave faster. Sounds simple, but this gets ridiculously complicated really quickly. The three things to remember though are the more you accelerate:

  1. The straighter you’ll travel and faster you’ll get there (which is awesome)
  2. The more you’ll have to de-accelerate at the other end (which sucks – you now need extra fuel to slow down, or take a mega heat shield to slow down using Mars’s atmosphere and risk skimming off it and into the cosmic abyss)
  3. The exponentially more fuel and energy you need (Newton’s 3rd law: to go somewhere you have to throw stuff in the opposite direction)

We’ll talk more about propulsion systems in the next post, but right now using traditional chemical rockets the quickest we can get to Mars is about 6 months. Which looks something like this:

Interplanetary transfer for the Mars Odyssey probe in 2001

Obviously you also don’t aim for where Mars is when you’re launching from Earth, because it won’t be in the same place you were aiming for 6 months later. Like throwing a water-bomb at a toddler you aim ahead to where your target will be in the future, letting gravity and the easily predictable path of a planet or under 5 do the work for you.

Because Earth orbits the Sun once every 365.25 days and Mars orbits the sun once every 687 Earth days*, they only line up for this kind of transfer once every 22 Earth months.

*Mars has a “day” of 24 hour and 36 minutes called a “Sol”, so 1 year on Mars is 668.6 sols

Alright, enough already

There a couple of other little tricks of gravity we can also use to get to Mars quicker and with less fuel too, namely Orbital Slingshots and Ballistic Capture.

Orbital Slingshots AKA “Gravity Assists” AKA “Big Thing Make Spaceship Go Fast”

Turns out you can actually use an entire planet to speed up your spacecraft if you’re willing to swing in close enough. The gravitational attraction between a planet and a spacecraft doesn’t just move the spacecraft – it also moves the planet a tiny fraction too! So by flying up behind a planet as it orbits and letting gravity swing your spacecraft towards it you’ll slow the planet down (increasing it’s “year” by a few nanoseconds) but massively increase the velocity of your spaceship!

The last diagram, I swear

This is actually what they use in The Martian to get the Hermes back to Mars and save Mark Watney. While Donald Glover is being a mentalist with a stapler in a NASA boardroom, he’s describing an especially powerful orbital slingshot. The speed boost the Hermes gets swinging around Earth is the reason they can get back to Mars so quickly, but it’s also why they’re going so fast at the other end.

Kristen Wiig will have none of your swingline shenanigans

Ballistic Capture

Recently we’ve discovered another way to get things from Earth to Mars that doesn’t require you waiting nearly 2 years for an alignment or having Sam Neill take you through a portal to Hell… but it’s even slower than the “Enya-Space-Sex” Hohmann Transfer. This “Ballistic Capture” approach involves getting just close enough to a planet or moon that it’s gravity slowly pulls your spacecraft into it at low velocity without needing any extra fuel to slow down. It’s just like knocking a pool ball towards a pocket and having it stop right on the edge: it’ll either roll in on it’s own after a few seconds, or you give the table a little bump to help it in.

Ballistic capture was used by the Japanese probe “Hiten” to orbit the Moon in 1990, but until recently it was believed that Mars was too small and too far away for ballistic capture to work. Some clever folks with a super computer recently worked out though that you can launch towards Mars anytime as long as you don’t mind taking up to a year to get there. For a human crew this would be like having sex to Enya playing at half tempo, so you might prefer the trip through actual Hell with the Event Horizon instead.

Before you realise Sam Neill is playing Enya through the PA too

For someone like Mark Watney though – slowly starving on Mars because his potato crops were suddenly freeze dried – this would have been pretty handy. Building a new probe full of food, testing it properly (rather than just glancing at it and saying “Yeah mate, she’ll be right”) and launching it on a 1 year trajectory using a ballistic capture would have been considerably quicker and safer than the mentalist orbital slingshot the Hermes crew do in the film. Although I guess staying put and eating potatoes for a few more years isn’t as “Hollywood” as:

  • Surviving 20 Gs while riding into space on a rocket with the front half of the capsule removed, using a canvas tarp over the holes… for decoration?
  • Explosively decompressing the pressurised living area of an inter-planetary spaceship (full of critical life support systems that can’t operate in a hard vacuum) to slow down
  • Instantly cutting through the dozen layers of rubber, canvas, Kevlar and Mylar in a spacesuit glove, then using the minuscule pressure in a space suit (less than what’s in a football) to “Be Ironman” and fly to safety…

Me during the last 10 mins of The Martian

So there you have it: orbital mechanics that’s awesome and not lame/boring. Obviously there is so much math to dig into if that’s what gets you off, and I’m not one to kink-shame: go and get wild solving three-body problems or dig out on the crazy equations describing Lagrange points, gravitational keyholes, Halo orbits, Lissajous orbits and Horseshoe orbits, or Hill spheres… if that’s your thing.

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Space – Choosing a Crew for Mars

With Mars One’s next astronaut selection round later this year looking to bring the current crop of 100 candidates down to 18-36 who will then start full-time training, I figured it was time to talk a little about how the next round will progress and what the selectors have said they want from the first Martian colonists.

When most folks talk about finding the “best” people for a job, especially when it’s space-related, there’s unfortunately one default reference pretty much every one leaps to:

It’s hardly a popular opinion, but the truth is today the “The Right Stuff” is a fantastic catalog of what NOT to look for when selecting astronauts for a mission to Mars. The Mercury program (and consequently “The Right Stuff”) was all about flying solo: selecting the best trained and most technically proficient pilots the US military had – who were the right size – and launching them alone on the US’s first foray into space. They had to meet incredibly stringent requirements: only test pilots under 40, no taller than 180cm (5’11”), no heavier than 82 kg (180lb), with a bachelor’s degree or equivalent (uncommon in 1959), and with over 1,500 hours flying time to meet even the basic requirements to apply at all. And don’t think the Russians were doing things differently back then: a huge factor in Yuri Gagarin being the first human in space was at 158cm (5’2″) and 70kg (153lb) it was easier to fit him inside Vostok 1. 

Good-sized hands though. The best hands. Very beautiful hands. Slightly large, actually.

I don’t say any of this to take away anything from any of the early astronauts – all of them were incredible people who dedicated and risked their lives to be the first to venture beyond Earth’s atmosphere. But it’s important to recognise the criteria the early astronauts were selected on is radically different from what future Mars mission astronauts/colonists will be selected on. From the first Russian space stations, to the US shuttle program, through to the astronauts selected for 6 and 12 month missions to the International Space Station, we’ve seen significant changes in the way selectors assess potential astronauts, and by far the biggest changes have been how candidates are psychologically screened and prepared.

The critical difference between the first people in space and now? You’re still hurtling through the darkness in a hazardous tin can; except now it’s a fraction larger, you’re going for a lot longer AND you’re going with other people… so just because you’re a really great pilot doesn’t mean you can get away with being a jerk anymore!

Sorry Steve – you’re staying home

There is still a requirement to be fit and healthy – I needed to pass the equivalent of a commercial pilot’s medical exam for example. But because we’re spending longer in space and not jamming people into tiny cockpits for the entire trip, being short and light isn’t such a necessity anymore (it still helps though). You also obviously still need to be smart enough to process all you’ll need to learn, which is why Mars One tested our technical knowledge during the interview phase. But given Mars One is planning on sending people to Mars for the rest of their lives, finding people who have a clear sense of purpose and get along with others under isolation and stress is way more important than finding people who are really, really good (and short) pilots.

Basically we need to find people who at the bare minimum can live together without someone turning into Jack Torrance after a few months.

Wendy! I’m home to the hab!

Given Mars One isn’t planning to launch a crew until 2031, they also have 12-13 years to train candidates – more than enough time to learn anything and everything they’ll need provided they have the right motivation and a proven capacity to learn.

So with a greater focus on 1) Why someone wants to live to Mars, 2) How they get along with others & respond to stressful situations while isolated, and 3) their ability to learn new things quickly; Mars One’s selectors identified five key characteristics they sought in an astronaut candidate: Resiliency, Adaptability, Curiosity, Ability to trust, and Creativity/Resourcefulness. The short answer? Mars One is essentially looking to send 4 MacGyvers to Mars who are also great housemates.

No, not the “new” series. I mean the one that was actually good.

I’ve always been a fan of the MacGyver approach: he knows what he’s trying to achieve, he knows what resources he has available, he knows how much time he has, and he doesn’t ask permission to use something in a unique or different way to solve a problem. In short, he survives because he’s a “do-er”. Even so, MacGyver was a bit of solo act: saving the day through knowledge, lateral thinking and cool under pressure… but usually on his own, and everything usually cut to fit a 48 minute episode. To find a much closer parallel to the psychological endurance required by the Mars One crew, we really need to look back more than 100 years to a group of explorers trying to cross the southern pole of this planet.

The 28 crew members of the “Endurance”

The story of Ernest Shackleton’s “Imperial Trans-Antarctic Expedition” (commonly referred to as the “Endurance Expedition”) is far better told by others elsewhere – “Endurance” by Alfred Lansing is brilliant, but even the Wikipedia entry is a great way to get an idea of what it was like: 28 men surviving back-to-back winters on the Antarctic ice after their ship was crushed in pack ice, before attempting one of the most daring rescue missions in history by paddling 1300km in open boats across the Southern Atlantic then hiking for 3 days across the unexplored interior of South Georgia to reach help.

Many look to Shackleton as one of the greatest leaders of all time, and rightly so. I’m currently rereading “Shackleton’s Way” by Margot Morrell, which focuses on the incredible leadership lessons that can be taken from Shackleton and the Endurance expedition. The entire book has countless pearls of wisdom that can be easily applied to the planning and execution of a human Mars mission, but arguably the most important is how Shackleton selected and prepared his crew. And even if you haven’t heard of Ernest Shackleton before, there’s a good chance you’ve heard of this though: 

“Men wanted for hazardous journey, small wages, bitter cold, long months of complete darkness, constant danger, safe return doubtful, honor and recognition in case of success. Ernest Shackleton 4 Burlington st.”

There’s been a persistent myth that Shackleton took out this advert to recruit for the Endurance expedition, but unfortunately it’s almost certainly #FakeNews. The reality is Shackleton didn’t need to put out an advert: he received more than 5,000 applications when the expedition was announced, which is surprisingly similar to the 4,227 people who submitted completed applications to Mars One (Note: 202,586 people registered & confirmed their online applications, but the process to actually complete the application was… thorough).

Shackleton had the applications sorted into 3 boxes: “Mad”, “Hopeless”, and “Possible”. You could argue everyone applying was “Mad”, but Shackleton was looking for people who knew what they were getting themselves in for, had the experience he needed, and most importantly shared his vision and enthusiasm for exploration. After discarding the “Mad” and “Hopeless” boxes, the “Possible” applicants were then put through some pretty unconventional interviews, like asking the expedition physicist if he could sing. Shackleton wasn’t looking for the “best of the best” – he was looking for people who were qualified for the work and could live together peacefully for long periods without any outside communication. In the wise words of the man himself “Science or seamanship weigh little against the kind of chaps they were”. As Mars One selectors Dr Norbert Kraft and Dr Raye Kass point out in their Huffington Post article on Mars One crew selection, Shackleton chose people who were optimistic and could keep morale up like musicians and storytellers.

Meterologist Leonard Hussey, and his banjo that Shackleton considered “vital mental medicine”

Above all Shackleton picked people who did their job really well, but weren’t prone to being miserable or obnoxious when things got tough. People who great at what they did, but focused on building a sense of camaraderie among the group and were always quick with a laugh especially when things have gone wrong. Rather fittingly, Ernest Shackleton went to Antarctica with people very much like Mark Watney…

As we head into the next selection phase of Mars One narrows the group down to the 18 to 36 who will start training, and as that training continues towards a launch date, more and more questions will be asked about the psychological challenges the crew will face, and ultimately what makes the ideal crew for a one-way mission to Mars. My suspicion is they will be the same kind of people who were aboard the Endurance in 1914 as it approached the pack ice: people who love what they do and working with the people alongside them, who know deep down why what they’re doing is important to them, and who love laughing at every ridiculous aspect of the bizarre adventure they signed up for together.