Klear wrote:I could have sworn Randall specifies the height somewhere in the article... I've got "9 km" stuck in my head, but no idea where it came from.
I did the calculation including the 9km result on a Monday evening entry to the
What-If 0053: "Drain the Oceans" forum (and as I write, the last entry). Sorry to be late to that party, but I was igniting the Eta Carinae supernova and my FTL drive broke down part way home. Don't worry, earthlings, you have 7743 years to dig in before the X-rays hit.
The volume of the Earth's oceans are about 1.35 billion km
3. Mars is 3396 km radius, the surface is around 145 million km
2. If all the seawater moved, and nothing stuck up too far on Mars, the height of the water would be 1350/145 or 9.5 km. But not all the seawater reaches the Earthside portal(s), and there are some enormous Martian mountains poking up above 9 km, so 9±1 km is a reasonable ballpark guess for how high the portal must be for water to keep flowing.
In that previous posting, I suggested enormous steel stoppers ("drain plugs") to manage the flow, and passing down the stream in plummeting submarines to colonize Mars. Better still, submarines can rendezvous with airlocks on the earth-side of the stoppers, while the flow is stopped. A 14 km or Kevlar tether can be lowered through the portal from inside the Earth stopper to the Martian surface - a baby space elevator. Even better, a loop of tether running between two large pulleys. This loop is powered by paddle wheels in whatever small flow is allowed through the stopper. I love the idea of interplanetary travel powered by water wheels.
For extra credit, compute the amount of hydropower that can be generated from the pressurized flow coming in, and from the further 9 to 14 kilometer drop (at 3.7m/s2 gravity) down to Lake Gale (I prefer the Gale Sea, see?). That should be enough to electrolyze 900,000 km3 of water and create a breathable 20KPa oxygen atmosphere for Mars.We only need to send through enough water to create a habitable Mars, a tiny fraction of the 1350 million km
3 of Earth ocean water available. Air dropped through the portal would also fall to Mars, but rather than move ordinary air, we can separate and drop only CO
2, which, along with a lot of methane, might create enough of a greenhouse effect to keep Mars warm for a while.
After colonizing Mars, we can resume our space program from there. The escape velocity from Mars is only 5 km/s, so single stage to orbit rockets will be much easier than Earth's 11km/s.
Using another portal to go directly to into space would not be sporting. The moons of Mars are also much closer and easier to land on, so a wussy little space program should be able to reach them. Luxembourg to the moon!