Al Stahler: Spaceship flyover Friday
Special to The Union
Two pounds of oxygen a day.
If you’re traveling through space, you’ve got to haul two pounds of oxygen for every day you’re out.
That’s two pounds of pure oxygen, not air.
Only one in five atoms of air is oxygen, so a day’s worth of air weighs five times as much — close to 10 pounds.
Designers of the Apollo mission hoped to avoid hauling all that air to the moon by putting into their vehicle an atmosphere of pure oxygen. Unfortunately, the seemingly useless four-fifths of the air that isn’t oxygen is still super-important.
The cars on a busy highway slow your race from here to there — try to go faster and you’ll crash into them.
Fuel burns when atoms of oxygen crash into it. But with all those other molecules in the air, oxygen atoms crash into one after another before they finally get to the fuel.
Fires burn much slower in air than in pure oxygen.
During an Apollo ground test, a stray spark ignited a bit of plastic or paper. Fire spread instantly — catastrophically — killing three astronauts.
It also killed the idea of flying to the moon with an atmosphere of pure oxygen.
Radiation shields, temperature control, waste management, food, water, air — you’ve got to haul a lot of stuff on a journey through space.
Of course, water can be recycled from sweat and urine, oxygen can be pulled from the water in your breath. But then, you’ve got to carry bulky recycling equipment, and the power source to run it.
If your journey through space lasts only a week or two — only into near-space — you can carry what you need in a fairly small craft, like the American space shuttle, the Russian Soyuz, the Chinese Shenzhou.
But to travel farther — into deep space — you need a far larger vehicle. Not a spacecraft, but a spaceship.
Earth has yet to launch a true spaceship, but we have built an experimental prototype.
That experimental spaceship will fly over northern California at over 17,000 miles an hour next Friday evening, just after sunset.
Revolving crews of six men and women have inhabited this prototype spaceship, The International Space Station, for 15 years.
The challenge of running a spaceship is hinted at by the fact that, on average, two of the six-person crew are busy with repair and maintenance.
To feed 100,000 watts of power into the station’s eight miles of wire, the ISS carries close to two-thirds of an acre of solar panels.
Two-thirds of an acre of solar panels absorb a lot of sunlight; they also reflect a lot, which will make the station very easy to spot as she flies over this Friday night.
She’ll be starting low in the northwest at 7 p.m. and almost directly overhead a few minuets later.
The International Space Station can never escape low-earth orbit. But one day in the future, a true spaceship will head out to other parts of the solar system.
If you’re up and outside before dawn, you’ve noticed Venus and Jupiter over the eastern horizon, both stars bright because they’re covered with clouds.
Just below Jupiter is another planet, not nearly so bright — sunlight reflecting, not off clouds, but off rock and sand. That’s Mars.
Al Stahler’s science programs can be heard on KVMR (89.5 FM). He brings an understanding of science and nature to students of all ages, and may be reached at firstname.lastname@example.org.
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