Six Minutes of Terror - Landing Humans on Mars

OriginalArlen writes "Universe Today has a fascinating article discussing the difficulty of executing EDL (entry, descent, landing) on Mars for vehicles bigger than MER, Viking and Pathfinder, and the challenges for manned craft in particular. Airbags can't be used for obvious reasons, but the atmosphere is too thin to be used for parachutes or aerobraking by large heavy vehicles. The stronger gravity (compared to the moon) makes an Apollo-style powered descent impossible. The best current idea is a huge inflatable torus called a hypercone: 'Imagine a huge donut with a skin across its surface that girdles the vehicle and inflates very quickly with gas rockets (like air bags) to create a conical shape. This would inflate about 10 kilometers above the ground while the vehicle is traveling at Mach 4 or 5, after peak heating. The Hypercone would act as an aerodynamic anchor to slow the vehicle to Mach 1.'"

Comments

Hydraulic despotism won't work any more

[Moraelin]

I like a good hyperbole as much as the next guy, but in this case "hydraulic despotism" is so over the top it's no longer funny.

Let's recap what it used to mean historically. It meant that your government can basically cut your only means of subsistence (as in, you _die_) if you disobey. Typically it was applied to water used for agriculture. E.g.,

- in Mesopotamia whoever controlled the sluices had, basically, the life and death of everyone else in their hand. That area was only able to produce enough food by irigation, so basically you obeyed or they could hurt you badly.

- in ancient Egypt, knowledge of the calendar was very important, since their whole agriculture depended on the Nile's yearly floods. So the priestly caste, who knew how to count days and calculate that kind of thing, accumulated disproportionate power. (Plus, used people's superstition to claim power over the river itself. You know, if you don't pay the priests well, Osiris will be angry and give you a crappy flood.)

Note that in both cases the punishment meant literally almost-guaranteed death, not just inconvenience or lack of privileges. As late as the late middle ages agriculture output was as low as 2 to 7 grains harvested per grain planted. So you'd have to work a large surface just to subsist and pay your taxes. Having your crop halved or quarterd because you were denied irrigation, would hit you _hard_. Chances are you didn't even have extra land or work power to compensate for that. And in early barter-based societies, that crop would also be your money, so you couldn't even buy much when something like that happened.

I'm sorry, but no resource imaginable nowadays comes even _close_ to that kind of life-and-death importance. And some of the examples used in SF stories (e.g., orbital rights) are outright laughable.

Also note that historically even this kind of despotism didn't work as well as SF authors like to pretend. Even with that kind of control, you can only push people so far before they revolt. The history of Mesopotamia and Egypt is full of revolts, invasions, usurpers, assassinations and other violent mishaps. The hydraulic empire didn't quite work half as well IRL as in, say, Dune.

Nowadays? Oooer. People might be complacent when it comes to minor deviations from the constitution, but I doubt that any (western) empire would have an easy time justifying to its citizens why it deliberately starved a city to death. I mean, look at the scandal around the government merely responding too late and too inefficient to the Katrina devastation. Now picture the government deliberately blockading a city and letting it starve. And flaunting it at that, because hydraulic despotism doesn't even work unless everyone knows you're willing to use that power. I doubt that even China could get away with it that easily.

So basically while it's a scary concept and makes for good novels... well, let's just say that so do Vampires, but you don't carry stakes with you IRL, do you?