Soon, Barack Obama must make a decision on whether to continue funding NASA's daffy plan to build a Motel 6 on the moon. The president will be put on the spot when the final report of a space commission (here is its preliminary report) is delivered. Rumor is that in keeping with the tradition of Washington commissions, the report will contain extremely vague language about sweeping reform; then cite every item on every wish list of every interest group with a finger in this pie; then recommend nothing specific, so as to offend no interest group; then close with a call for higher subsidies. NASA is not one of the core missions of government, and spends only one-half of 1 percent of the federal budget, so space waste is relatively minor in the scheme of things. But if public policy can't get this right, what can it get right?Of course, I completely disagree that space solar power is a good idea...I think it is a terrible, terrible idea. But other than that, I couldn't agree more.
Right now NASA's budget is $18 billion annually, and the quarter or so spent on science -- planetary probes, telescopes that scan the far universe -- is going very well. The rest of NASA is a mess. The agency has just thrown $100 billion of your money down the drain on the space station, which has no scientific achievement and no known purpose other than keeping checks in the mail to favored contractors and congressional districts. The station is such a white elephant the current plan is to "deorbit" the thing in 2016. "Deorbit" is polite for "make it burn up in the atmosphere." So after spending $100 billion to build a space station, we'll destroy it. Your tax dollars at play!
Since 2004, NASA has said its next goal is a manned outpost on the moon, as a stepping-stone to manned travel to Mars. There's nothing a person could do on the airless, lifeless lunar surface that a tele-robot operated from a Houston office building could not do at a fraction of the price and risk. And the moon has nothing to do with Mars. Any Mars-bound mission will leave directly from low-Earth orbit to the Red Planet: stopping at the moon, then blasting off again, would consume the mission's fuel to accomplish nothing. Though NASA has been studying moon-base and Mars-mission proposals for five years, the agency refuses to give a cost estimate -- a sure sign the plans cannot pass a giggle test. Considering the space station price was $100 billion for a limited facility that was not accelerated to the speed necessary to reach the moon -- speed means fuel which means higher price -- even a Spartan moon base easily could cost several hundred billion dollars. For what? Why, for "economic expansion"! Today, no one is interested in economic expansion at Earth's poles, which are far more amenable to life than the moon, have copious resources, and can be reached at one-ten thousandth the cost of reaching the moon.
What about Mars? That planet is fascinating, and people are sure to go there someday. But until there is a fundamental breakthrough in propulsion, Mars travel will be ultra-expensive and extremely impractical. Today's chemical rockets are little different from those of the Apollo era, meaning the great cost of getting weight into orbit and then to escape velocity, coupled with long travel times, remains a high barrier to any Mars mission.
The fastest trajectory available with current propulsion is a 520-day Mars mission, and that only gets you 30 days on Mars -- the rest is transit time. Now think about weight. The Apollo vehicle, which was 45 tons at departure from low-Earth orbit, carried three people on a maximum mission of 13 days. That's 1.1 tons per person per day. A Mars-bound mission would require less fuel per day, but a lot more weight for supplies, interior volume, multiple redundant systems and radiation shielding that was not required for moon flight. Interior volume is essential. The crew was strapped into seats in the Apollo command module; they couldn't even stand up. For a nearly two-year voyage, the crew will need to be able to get up and walk (or float) around to avoid going bonkers. The Russian and European space agencies recently locked volunteers into a spacecraft-like big chamber to see how long they could stand it; they were able to stand it for 105 days, a fifth of the length of the fastest possible Mars mission. (Hilariously, the agencies announced the volunteers "simulated a 105-day Mars mission full of experiments and realistic mission scenarios." This scenario is "realistic" only using warp drive.)
Any Mars craft will need to provide at least some private space for each crew member, and a decent exercise facility, to stave off the muscle loss and bone decay that is triggered by zero-gee. At least one fully equipped surgical theater will be required. Loads of spare parts and loads of equipment to use on the Martian surface will be needed, versus Apollo, which carried no spare parts and no equipment beyond a small, short-range dune buggy. (Most likely a Mars mission would not be a single vehicle -- unmanned cargo craft would go first, and people would not leave until supplies were in place -- but the weight's the same regardless of whether it's a single vehicle or a collection of launches.) Considering these things, the 1.1 tons per person per day of Apollo may prove conservative for a Mars mission.
Anyway, suppose that number is right. Assume a Mars crew of six people -- two astronauts, two scientists and two surgeons -- on a 520-day Mars mission. (Two surgeons are needed in case one of them gets injured.) Based on the Apollo experience, our six-person Mars mission gone 520 days would weigh about 3,400 tons at departure from orbit. That's approximately the displacement of an Oliver Hazard Perry class guided-missile frigate, and we are not launching a frigate to Mars anytime soon.
My weight estimate didn't pop out of the sky. These numbers have been debated by specialists for decades, and have not changed much by recent tech developments -- for example, electronics are a lot lighter now than in the Apollo era, but since electronics compromised less than 1 percent of Apollo's weight, new miniature stuff does not do much for weight. Two-thirds to three-quarters of the mission weight will be fuel, and fuel weight hasn't changed. In the 1950s, Apollo designer Werner von Braun projected that a Mars mission would weigh 3,700 tons. In the 1960s, von Braun supposed the mission could weigh 1,600 tons if nuclear propulsion was developed, but that hasn't yet happened. Discovery One, the imaginary planetary spaceship in the 1968 movie "2001: A Space Odyssey," was described as weighing 5,400 tons, which oddly sounds about right. In 2007, a NASA workshop supposed a Mars mission might weigh only 400 tons, an utterly unrealistic budgetary lowball number.
The true numbers are budget busters! Because it costs about $20 million to place a ton of anything into low-Earth orbit, the heavier the Mars craft, the higher the price. Merely placing into orbit the 3,400 tons of a conjectured mission would cost about $70 billion. That's just the launch cost -- construction of the spaceship is extra! If space station total costs are a basic guide, the full price of a 3,400-ton Mars mission would be $1 trillion. Converted to today's dollars, the entire Apollo program -- not one mission, the entire program -- cost about $140 billion.
Now you see why NASA won't estimate prices.
The shame is that while NASA toys with monumental waste of tax dollars on a moon base and speaks of a Mars mission it knows full well is inconceivable using current propulsion, the agency is not even considering two space initiatives that could return tangible benefits to taxpayers: protection against asteroids and space solar power. Sunlight collected in space where its energy value is far higher than on the ground, then beamed to Earth as microwaves, might provide a long-term fossil-free solution to the planet's energy needs. No one knows if space solar power is practical. But NASA won't as much as fund a demonstration project; all money must go to moon base subsidies and Mars plans.
Aware its current course makes no sense, NASA may soon roll out the reddest of red herrings -- we've got to go back to the moon to beat the Chinese and the Indians. During the Cold War, no one questioned NASA spending because national prestige was involved. Why must we "beat" China and India to something we already did 40 years ago? If China or India beats us to space solar power -- now, that would hurt.
_
0 comments:
Post a Comment