I posted last week about the silliness of trying to colonise Mars on a one-way basis, unless you’re sending Justin Bieber.
Sure, most colonists here on Earth made the trip one-way. But Earth’s way more hospitable. Even Roanoke. You can breathe the air, for a start.
Mars – that’s another planet. It has red skies and blue sunsets, temperatures that make Antarctica look summery, and surface air pressure about 0.6% that of Earth, though that’s academic because it’s mostly carbon dioxide anyway. Mars also has no magnetic field, which means the surface is irradiated from space. Then there’s the dirt, which the Phoenix lander found was saturated with naturally-formed perchlorates. Know what perchlorate is? Rocket fuel. It’s nasty stuff, it’s toxic, and the chances of keeping the habitat clear of it after a few EVA’s seems low.
The biggest problem is that nobody’s been there yet. There’s bound to be a curve ball we don’t know about. It’ll be discovered the hard way.
That was the Apollo experience forty years ago. It turned out lunar dust is abrasive and insidious. As early as Apollo 12, astronauts found dust in the seals when they re-donned their suits for a second EVA – moon-walker Pete Conrad reported that ‘there’s no doubt in my mind that with a couple more EVA’s something could have ground to a halt’. All the later Apollo astronauts hit it; leak rates soared in the suits as dust worked its way into the sealing rings.
I think it’s safe to say something of equal practical difficulty will be discovered about Mars, one way or another. Not good if you’ve just arrived – permanently. Besides, what happens if someone gets needs a hospital now? Or is injured? Well, that’s a no-brainer. You can imagine the colony consisting of a cluster of grounded Dragons with a row of graves next to it.
Mars One plan to send more missions every two years, each with four colonists to join the happy bunch. If they’re alive. My money says they won’t be. This is Scott of the Antarctic territory – high-tech for the day (Scott even had motorised tractors) but still gimcrack.
The main reason we’ve not gone there yet, despite space agencies making serious plans since the 1960s, is cost. Manned interplanetary fly-bys were (just) within reach of the hardware built for the Moon landings – and until the Apollo Applications Programme was slashed to just Skylab, NASA was looking at a manned Venus flyby for 1973-74, using Apollo hardware.
Unfortunately, stopping at the destination, landing on it, and all the rest was another matter. It was easy to accelerate an Apollo CSM and habitat module into a free-return Venus or Mars trajectory; no further fuel was needed, it’d whip past the target at interplanetary velocities, and the CM could aerobrake to a safe landing on Earth. But stopping at the destination, landing and then returning home? In rocketry – whether chemical or nuclear-thermal (NERVA), the two technologies available until recently, mass-ratios are critical.
Mass ratio is the difference in mass between an empty and fuelled rocket at all times, and fuel takes fuel to accelerate it. It’s a calculation of sharply diminishing returns, and the upshot for NASA and other Mars mission planners in the twentieth century was that a practical manned landing mission was going to (a) require a colossal amount of fuel, and (b) would still transit by low-energy Hohmann orbit requiring a 256 day flight each way, meaning more life support, which meant more fuel (see what I mean?).
Some plans looked to refuel the system from Martian resources, but that had challenges of its own. Either way, the biggest challenge in all Mars mission schemes was the first step, lifting the Mars ship off Earth into a parking orbit. No single rocket could do that in one go, meaning multiple launches and assembly in orbit, raising cost and complexity still further. With figures in tens and hundreds of billions of dollars being bandied about, and no real public enthusiasm for space after Apollo, it’s small wonder governments were daunted.
My take – which is far from original to me – is don’t try going to Mars now. Focus on building a space-to-space propulsion system that offers better impulse than chemical or nuclear-thermal motors. Do that and the 256-day trans-Mars cruise – which is what drives the scale and risk of the mission, including problems with radiation doses in deep space – goes away. One promising option is the Variable Specific Impulse Magnetoplasma Rocket (VASIMIR), a high-powered ion drive that might do the trick if it works as envisaged. Another is the FDR (Fusion Driven Rocket). Current projections suggest Earth-Mars transit times as low as 30 days.
Of course, if your drive won’t light when you need it to slow down, you’re on a one-way trip out of the solar system. But hey…
Maybe we should send Justin Bieber on that first VASIMIR mission, just in case…
Copyright © Matthew Wright 2015