My last post discussed when we can go to Mars (once every 780 days, all tickets non-refundable) given the realities of orbital mechanics, and how long it will take to make the journey (180 days more or less, usually a bit more) based on our current rocket technology. Mildly depressing, but do-able.
But 180 days! That's a long time to be sitting in a ship listening to Alice humming the same freaking tune over and over and over, and if Bob makes that clicking noise in the back of his throat one more time I swear I'll grab a can opener and jail-break my way out of this thing. And "sitting" will almost certainly be a figure of speech as in the primitive craft of these early days there probably won't be anything resembling gravity, which means you'll be drifting around like a party balloon for months on end, eating everything out of bags and bulbs and paste out of trays, and getting rid of the waste products will be a very careful experience as you certainly don't want THAT stuff floating around in your cabin for the rest of the trip. And of course, that idiot Leonard WILL forget to close the back-check valve before starting the evacuation pump so bring a mask.
We can safely say that while the trip is possible it will be cramped, boring, and uncomfortable.
So, people and their needs. When we talk about "sending a person to Mars" what does that entail? What constitutes "a person"? Well, let's use Leonard as an example. There's him; we know that the average mass of a person globally is 60 kilograms, Europeans average 70 kilograms and, of course, everyone has to excel at something so we North Americans average 80 kilograms. Leonard is from Belgium (it is an international effort), so 70 kilograms plus a 5 kg baggage allowance gives us 75 kilograms. Then we will have to bring along everything that Leonard will need to keep him alive, which at a minimum is food, water, and air.
Food is an easy one. The good people operating the International Space Station (ISS) have been running a space-catering business for years, so we can confidently say that Leonard can get by just fine on 1.75 kg of food per day, so 1.75 kg * 180 days = 315 kg of food. 340 would be better because more is better than less and you can't order out.
Water is much more complicated, as you can see from the diagram below. There is the water moving through Leonard's body, about 2.5 liters/day, but there is also washing, showering, maintaining comfortable relative humidity, etc. The ISS has been recovering 25 liters per day from six people, or a bit more than 4 liters per day per person, for the past twenty years, so if nothing breaks water shouldn't be a problem. But we all know that the framis on the hoodjat will break the day after we leave LEO, so an emergency reserve (2.5 liters/day * 180 days = 450 liters = 450 kilograms) is mandatory.
How water moves through Leonard's body.
Finally, there is air. Breathing is good. Happily, we have over fifty years of submarine technology dealing with the process of creating breathing air out of- wait for it- water! Run a current through water and oxygen and hydrogen comes off the anode and cathode, and collecting the gases is dead simple. The hydrogen can be run through the Sabatier System, which combines it with the carbon dioxide waste gas that Leonard produces when he breathes, creating CH4 which is the rocket fuel that the new SpaceX Raptor rocket engine runs on. It's also the fuel that vehicles on Mars Surface will almost certainly burn, so I'm sure we can find a use for it. Leonard "burns" about 0.875 kilos of oxygen per day, and the ISS has equipment that can routinely generate that amount, but of course, there is always the framis on the hoodjat, so (0.875*180 = 157.5 kg) another 160 kilograms of water for emergencies.
And that is it. One Leonard (we're applying to make that an International Standard Unit) equals 75 kg of himself + 340 kg food + 450 kg water + 160 kg air = 1025 kilograms. The next question is, how many Leonards can we send in one bus?
Today's gold standard for moving mass from Earth Surface is Falcon Heavy, which is rated to carry 63,800 kilograms to LEO and 16,800 kilograms to Mars Surface. Yes I know I know, Starship and the Chinese and maybe Blue Origin in a few years, but TODAY, FOR SURE, we can yeet 16,800 kg from here to there with an existing machine. (Pretty impressive, actually.) That's terrific, now we need to pick a craft that our Leonards can live in. Leafing through the brochure, the number of reasonably available spacecraft appears to be... none. There is an airtight people-can out there called Crew Dragon, which SpaceX uses to move people to-and-from the ISS, but it has some serious shortfalls that would need to be rectified before it could travel to Mars. It needs landing legs, it has no long-term life-support systems, and it is too small to carry people and cargo on an extended journey. In my opinion, at least one of these ultimately isn't fixable. Crew Dragon has an internal volume of 328 cubic feet, roughly a room 7x7x7 feet, and there is no way we are going to fit a herd of Leonards, a couple thousand kilos of cargo, and several life support systems into that space. So, we currently don't have a craft that can take our Leonards to Mars.
We COULD attach a habitat to Crew Dragon that would resolve the living space, cargo storage, and life support systems. Crew Dragon has an airlock connection, so it would be a trivial issue to attach a habitat, live in it en route to Mars, and then leave the habitat in Low Mars Orbit (it has obvious future utility) and use the Crew Dragon to land on its shiny new legs. But of course, a habitat will weigh a lot and now we don't have enough fuel to get everything to Mars.
Rats. So, we need a rebuild, a rethink, or both. Don't get discouraged, space is hard. If this was easy someone would have already done it, but that does not mean it cannot be done.
The easiest way to address this is to launch the Falcon Heavy to LEO with no payload. That results in the Falcon Heavy's second stage, which weighs just under 4 tons, having 85.5 tons of fuel onboard when it reaches LEO. 85.5 tons of fuel will take 35 tonnes to Low Mars Orbit, and since the Crew Dragon plus four Leonards plus a full load of hypergolic fuel for landing weighs 15 tonnes we can now send an additional 20 tonnes to Low Mars Orbit, which sounds a lot like a customized Dragon XL (yes, there is such a beastie, at least in the fever-dreams of SpaceX engineers) with an airlock that attaches to the front of Crew Dragon.
An Artist's Rendering of Dragon XL
Once we have a Falcon Heavy second stage sitting in LEO with 85.5 tons of fuel, we can send up two Falcon Nines with the actual payload. The first one would carry a Crew Dragon, four Leonards, and a full load (2600 kg) of hypergolic fuel. That would weigh 16,200 kg, well below a Falcon Nine's capacity of 22,800 kg. The second Falcon Nine would carry the modified Dragon XL, which could weigh up to 18,200 kg with a maximum dimension of roughly 5 meters in diameter and 15 meters in length as it needs to fit inside the Falcon Nine's large fairing. The currently designed Dragon XL weighs roughly 14 tons loaded, so there's lots of room for increasing the pressurized volume, adding the life support systems, etc. Once everything is in orbit, attach the Crew Dragon to the fueled Falcon Nine second stage (the clamps are already there), attach the Dragon XL to the front of the Crew Dragon (it's a standard airlock mechanism), and you have a ship that's ready to go to Mars! Once the craft is in Low Mars Orbit the Crew Dragon detaches from the Dragon XL, which is an excellent and ongoing resource in orbit (think LMO space station), and the Falcon Heavy Second Stage (which is still a perfectly functional pusher unit that just needs fuel to be reused), and proceeds through aerobraking and its internal engines to land on Mars Surface. Yay! We got four Leonards to Mars!
The bad news; all the Leonards will now die. They are sitting on Mars Surface in a craft that has no fuel and can't be refueled as they are designed to burn special fuels, the Leonards ate all their food on the trip from Earth, and they have no supplies left. So we need to send another Crew Dragon to keep them alive for the twenty-six months until another Crew Dragon shows up to keep them alive for another twenty-six months until... So, a qualified success at best. We could overcome this to some degree by sending a fleet, perhaps four Crew Dragons plus Habitats and another eight or so Cargo Dragons, which would give us a dozen craft on the ground for the sixteen Leonards to modify into habitats.
Artist's depiction of a flock of Red Dragons on Mars Surface
So we could make it LOOK like colonization, but it isn't really. I just described the history of Canadian colonization, by the way. Small groups of European 17th-century Leonardos watched their ships sail back to Europe in late summer, and the ones who didn't starve or freeze to death or die of disease got to die anyway if the ships didn't return the next year. Colonization has always been hard.
Establishing a colony in Low Mars Orbit would be MUCH easier as we already have the Dragon XLs and the pusher-units in Low Mars Orbit and we don't have to solve the Landing And Taking Off Problem. The basic problem is we don't have a big enough craft to get decent-sized equipment and materials to Mars Surface, and we need decent-sized equipment if we are going to build a viable community. Elon Musk figured all this out a long time ago, we need his Big-Ass Spaceships if we are going to have any chance of pulling this off.
My next posts will discuss a few options for making the trip more quickly, more comfortably, or both.
Thanks for reading along!
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