Thursday, February 26, 2015

Bubble Colony

Now that we’ve visited the moon a few times, nobody is talking about setting up a moonbase. Everybody seems to want to move on to colonizing Mars. But you know what? Venus is a lot closer.
Earth’s orbit is 93,000,000 miles from the sun. Mars’ orbit is 141,600,000 miles from the sun. The closest Mars and Earth can get is about 48,600,000 miles, while the furthest away they get is 234,600,000. Venus is 67,000,000 miles from the sun, so the closest Earth gets to it is 26,000,000, and the furthest away Venus gets is 160,000,000. So yes, it’s about half the distance to get to Venus as it is to get to Mars.
Why is nobody clamoring to colonize Venus?
At first glance, Venus does not seem very welcoming. Oh, sure, it has about the same amount of gravity as Earth, but that’s the only thing that might be called ‘welcoming’. Its atmosphere is carbon dioxide and nitrogen, with clouds of sulfuric acid droplets. There may be trace amounts of H2O and HO in the atmosphere, but don’t expect to go outside without a space suit. The corrosive atmosphere is so dense, no probe that landed on Venus lasted longer than a couple hours. If the acid doesn’t get you, the pressure will. That pressure is the same as being 1.5 miles deep in the ocean. And that’s assuming you don’t land in a volcano, because the surface is highly volcanic.
The atmosphere is the cause of runaway greenhouse effect, and the surface of Venus is about 900°F. Venus rotates backwards, so the sun rises in the west and sets in the east, but it rotates so slowly, a ‘day’ (single rotation) on Venus is 243 Earth days, while it only takes 225 Earth days to complete a circuit around the sun. That would take some getting used to. And despite Venus’ slow rotation, the top lay of clouds whip around it in about 4 Earth days, at speeds of 225 (or more) miles an hour.
Ready to make it your home yet?
There are people considering how it could be done. They don’t see a colony on Venus’ surface, however; they envision an enclosed ‘station’ that floats 30 miles above Venus’ surface, where the pressure is about the same as sea level on Earth. The temperature would be about 160°F, but that would be relatively easy to deal with. And being below that top layer of clouds, it might be pushed around the globe, but not at hurricane speeds.
That doesn’t sound so bad. Maybe they could devise a way to grow plants on the outside walls to change some of the carbon dioxide into oxygen. If enough of that happened, the greenhouse effect could start to calm down, the temperature might lower, and those racing high-level winds would slow down. Who knows, maybe it would be possible to establish a base on Venus’ surface... in a few millennia.

Ready to ship out yet? Or are you waiting for the ship to Europa?

Wednesday, February 18, 2015

Here There Be Dwarves

I’ve been looking into this ‘Dwarf Planet’ issue. I was not happy to have Pluto no longer be a ‘real planet’, but decided maybe it made sense to have another classification for those items in our system that did not quite fit the definition of ‘planet’. Of course, they devised that definition so that it would exclude Pluto, because another body they did not want to consider as a planet was roughly the same size as Pluto. Or so it seems.
Still, it works, as long as they use the definition of ‘dwarf planet’ consistently, right? But, are they?
Mercury is a planet (now called a Classic Planet). It’s about twice the size of Pluto, so... They had to put the dividing line somewhere, right?
Eris is further out than Pluto, and may or may not be as large. The diameters for these two said Pluto was slightly larger, but each had a margin of error. So, if Eris is larger than they think, and Pluto is smaller than they think, then they could be the same size, or Pluto could be slightly smaller. Ergo, if one is a dwarf planet, it makes sense that the other is also.
I had never heard of Makemake or Haumea until I started this research, but they have both been named dwarf planets. Their diameters are each a bit more than half of Pluto’s.
One rule of the definition of a dwarf planet is that it must have enough mass to pull itself into a roughly spheroid shape. It has been postulated that these bodies would need a diameter of at least 400 km before that was likely. I was surprised to read, then, that Haumea was not a sphere - its diameter through the equator is much longer than its diameter through the poles. The explanation (excuse?) was that Haumea rotates so fast, it has warped into a flattened shape.
So far, Ceres is the only asteroid to be named a dwarf planet. Its diameter is less than 1,000 km, but it is the largest asteroid. There are at least 3 other asteroids that are over that minimum diameter of 400 km, and so far as I have been able to discover, they are at least roughly spherical.
There are also 10 or more heavily bodies beyond the orbit of Pluto that are currently under consideration for being Dwarf Planets.
And that brings us to Charon. Long known as - and even now considered - Pluto’s moon, I suggest it be named a Dwarf Planet. Charon’s diameter is slightly less than half of Pluto’s, considerably larger than Ceres’. Yes, there are plenty of big moons in our system, but none of them are so large in relation to the planet they circle. And, technically, Charon does NOT revolve around Pluto. With this division of mass between them, both Charon and Pluto revolve around a point that is between them.
At least one astronomer has suggested that Pluto and Charon be considered a double Dwarf Planet. I definitely agree.
Name
Diameter (km)
# Moons
Mercury
4,879
0
Pluto
2,368
5
Eris
2,326
1
Makemake
1,430
0
Haumea*
1,300
2
2007 OR10
1,280

Charon
1,207

Sedna
1,000

Orcus
946

Ceres
942
0
2002 MS4
934

2005 UQ513
920

2007 UK126
880

Salacia
854

Quaoar
844

Ixion
804

Varuna
700

Pallas
544

Vesta
525

Hygiea
431


* NOT spherical