Imagine that the United States had ignored the territories acquired in the Louisiana Purchase. At first, this was a hostile territory and much of it was considered a desert. Ignoring the American West might have left the Native Americans better off, but the United States would be radically reduced. Other European nations were then actively exploring the territory, as other nations are today exploring space. In the hostile territory of space there is, fortunately, no indigenous population to abuse, and we already know that the resources are there.

... there is no economic case for space exploration. If the goal is to increase employment or spur technological innovation, then the dollars invested in NASA would be better spent elsewhere ...

... Many of the innovations we credit to the space program - such as Teflon and Velcro - were actually invented outside it. Others originated in space research, but the return the government got on its R&D investment was fairly slim. To invent somethig like the CAT scan, to use one of Bush's examples of NASA innovations, it would be a lot cheaper and wiser simply to invest in medical research, rather than in moon shots. ...

When John F. Kennedy announced his moon program, in 1961, the budget deficit was about 3 percent of the total budget. ... This year, the budget deficit is about 17 percent of the budget - when you exclude Social Security, 36 percent. ... you have to wonder where we're going to get the money.

Bush's plan [to go to Mars] sidesteps the budget question by proposing that all the spending be backloaded. ... The President gets the credit for the big, bold idea, and his successors get the bill. ...

... There is no longer much pretense that shuttle flights in particular, or manned space flight in general, has any practical value. You will still occasionally hear people repeating the old NASA lines about the joys of microgravity manufacturing and insights into osteoporesis, but if you repeat these tales to a materials scientist or a physiologist, you will get peals of laughter in return. To seek a cure for osteoporesis by spending $500 million to put seven persons and 2000 tons of equipment into earth orbit ...

...

... There is nothing - nothing, no thing, not one darned cotton-picking thing you can name - of either military, or commercial, or scientific, or national importance to be done in space, that could not be done twenty times better and at one thousandth the cost, by machines rather than human beings. ...

... this mission was a yawn - a low-priority "science" flight forced onto NASA by Congress and postponed for two years because of a more pressing schedule of construction deliveries to the International Space Station. The truth is, it had finally been launched as much to clear the books as to add to human knowledge, and it had gone nowhere except into low Earth orbit, around the globe every ninety minutes for sixteen days, carrying the first Israeli astronaut, and performing a string of experiments, many of which, like the shuttle program itself, seemed to suffer from something of a make-work character - the examination of dust in the Middle East (by the Israeli, of course); the ever-popular ozone study; experiments designed by schoolchildren in six countries to observe the effect of weightlessness on spiders, silkworms, and other creatures; an exercise in "astroculture" involving the extraction of essential oils from rose and rice flowers, which was said to hold promise for new perfumes; and so forth. No doubt some good science was done too - particularly pertaining to space flight itself - though none of it was so urgent that it could not have been performed later, under better circumstances, in the under-booked International Space Station. The astronauts aboard the shuttle were smart and accomplished people, and they were deeply committed to human space flight and exploration. They were also team players, by intense selection, and nothing if not wise to the game. From orbit one of them had radioed, "The science we're doing here is great, and it's fantastic. It's leading-edge." Others had dutifully reported that the planet seems beautiful, fragile, and borderless when seen from such altitudes, and they had expressed their hopes in English and Hebrew for world peace. It was Miracle Whip on Wonder Bread, standard NASA fare. On the ground so little attention was being paid that even the RADARs that could have been directed upward to track the Columbia's re-entry into the atmosphere - from Vandenberg Air Force Base, or White Sands Missile Range - were sleeping. As a result, no RADAR record of the breakup exists - only of the metal rain that drifted down over East Texas, and eventually came into the view of air-traffic control.

• There is no reason to "mourn" the end of the Shuttle program. It was a $200 billion boondoggle, useless. End of manned space program is no loss; more worrisome is that the unmanned program is dying too. Most of manned space program for last 30 years has been a waste. ISS was opposed by every major scientific organization; has no scientific value.



• Repairing the Hubble space telescope was one of the few "scientific" contributions of the Shuttle program. But for the cost of a few Shuttle missions, we could have built a complete new telescope and launched it.



• The postulated industrial/manufacturing uses of the ISS or a Moon base are nonsense; costs are far too high.



• For the cost of a single manned round-trip to Mars, we could send 1000 or 10000 rovers to Mars. And robots are getting better and better.



• Private companies exploring beyond Earth orbit isn't going to work; it's just too expensive, takes too long, and there's no business purpose for it.



• In a manned mission, 99% of the cost is expended just to get the humans there and back. Only 1% is left over for actually doing anything at the destination.



• Chris Kraft (spelling ?) estimates the cost of a manned round-trip to Mars is about 10x the cost of a one-way manned trip to Mars PLUS robotic one-way trips to keep resupplying them for the rest of their lives. The round-trip gets better if you can manufacture fuel on Mars. But the additional radiation of a round-trip might be lethal. Lots of unknowns.

> Do you miss the space shuttle?

No. In spite of the fact that I designed parts of it, I think it was a disaster. It should have been retired -- it cost far too much and was unsafe.

... Today it costs US$10,000 to US$20,000 per kilogram, just to get to low Earth orbit (LEO). It is a rare industry that can make a profit with cargo rates this high. This price has barely changed since Apollo, in constant dollars. ...

Why the space station? ... no one talks about why we keep the stupid thing up there. More than $100 billion has been invested to produce a smelly tin can that periodically threatens to break down, and in which almost no significant scientific discoveries have been made. Why are we still wedded to this project, other than the claim that it fosters international science cooperation? For that misty goal, the space station pales in comparison to the Large Hadron Collider, which cost one-tenth as much, involves far more countries, and actually does real science.

Despite being a huge space nerd for many years, I've gradually come round to monkeys in deep space being a Really Stupid Idea. For the next few decades at least.

• First off, the wonderful, magical thing about the Earth is that - unlike the Moon or Mars or deep space in general - it has a damn great magnetic field around it and a thick atmosphere. This serves two purposes: it deflects galactic cosmic rays (GCRs) and it deflects solar flares and their associated solar proton events (SPEs).



• So problem #1 with leaving the Earth's magnetosphere is that you're exposed to a constant barrage of GCRs. They stay at a pretty constant level, and that constant level is .3-.7Sv/year (Sv being the sievert, the SI unit of effective dose) depending on where we are in the solar cycle. Now as far as chronic doses like this go, each sievert you absorb corresponds to a (linearly increasing) ~5.5% chance of getting cancer. What I'm saying is that if you stick a colony in deep space without shielding, everyone will get cancer and die inside 20 years. Things are a little better on Mars, where the weak-but-present atmosphere and having your backside shielded by the planet dissipates some of the dose, but it's still sitting at .1-.3, which is still utterly lethal in 30-40 years. Even with shielding, you better hope your colonists are doing all their work inside else it'll knock a fair chunk of them out anyway.



• Problem #2 is the aforementioned SPEs. These are occasional events, and vary hugely in magnitude, but a medium-sized one can dump 2Sv in an hour. For the big ones, it's an order of magnitude higher. With an acute dose of 2Sv, you don't have a 11% chance of getting cancer, you have a 100% chance of bleeding out of every orifice by the end of the week. More, these things can arrive at Earth within 15 mins of leaving the Sun, which means that in a space colony no-one could venture more than 15, 30, 60 minutes (depending on how far from the Sun you are) from the nearest shelter. On a Moon or Mars colony, you can of course travel as much as you want during the night, but if your rover breaks down 8 hours out you are In For It.



• Of course that's all without shielding. What about with shielding? Well, there are two kinds:



• Active shielding ! Active shielding systems propose to emulate the Earth's magnetosphere with damn great superconducting magnets. Because SPEs and GCRs move at significant fractions of the speed of light though, they need to be truly vast and ridiculously intense, leaving them out of the question for the near future. Maybe, someday, we'll have the power supplies and materials to do this sh*t, but it ain't happening any time soon. "But with another Apollo program, we'd solve it!" I hear you say. No, we wouldn't. Things like "really f**king good superconductors" and "awesome energy supplies!" are things that'd be hella valuable everywhere else on Earth, so if they were only a few billion dollars away we'd have them already.



• Passive shielding ! Passive shielding works on the principle of putting a lot of nuclei between you and the radiation source. The obvious thing to use is stuff up the periodic table like lead, but unfortunately when a relativistic particle runs into a huge nuclei, the huge nuclei absorbs the relativistic particle ... and spits out a couple more. The latter bunch aren't as relativistic, but they'll still chew holes in your brain. Heavy-nuclei shielding actually makes things worse. Instead, you have to use small nuclei - hydrogen ideally - which work to gradually slow the particle down through many many collisions. This means the best passive shielding material ever is stuff like polyethylene, but regolith will do too. Estimates vary on how much shielding you need, but they all hang around "a couple of tonnes per square meter", and the more the better. Obviously this is easy enough to find on planets and asteroids, but it pretty much rules out classic-SF space stations.

Something else I should mention: as bad as deep space radiation is, there are a couple of places in the solar system where it's worse. The first place is close to the Sun. Your warning for SPEs drops, and the dosage goes through the roof. Those solar arrays orbiting just above the heliosphere? Maybe we'll build them one day, but no human is going to get to see them up close. Hell, silicon will have a hard enough time down there. The other bad places are in Jovian orbit. While Jupiter does have a spectacular magnetic field, and it does indeed deflect GCRs and SPEs, Jupiter unfortunately spews out its own barrage of radiation, and that fantastic magnetosphere then traps it all and rains it down upon the moons.

(There's one exception - Callisto - that's far enough in to be protected by the magnetosphere but not so far as to get eviscerated by the radiation belts. It only gets ~40mSv/year, which while ten times the Earth background, is kinda-safe-enough for it to be one of the few Non-Stupid places to live in the solar system. Unfortunately it's also f**king miles from Earth. Similarly, some of the other outer-planet moons are decent targets.)

So, conclusions: traditional space stations are out. Traditional colony ships are out too, but they're daft anyway. If you want to do Mars, Moon or asteroid colonies with regular ole' humans, the base is going to be several meters underground and you better manage their time on the surface damned well. More, your workers will likely refuse point-blank to go more than an hour from a shelter, what with the risk of sudden death and all.

Where does that leave us? With what we've always known, that humans are woefully ill-designed for space exploration. The entire radiation thing aside, we're a kilo or so of (pretty wasteful) computational matrix stuck in 70kg of meat that needs >10,000kg of life support in order to have any hope of functioning off of this planet. When considering the mass budget, if you think them's good economics then you're plain crazy.

Fortunately, for every worthwhile thing space offers us as a species, there're some damn good alternatives. Anyone who's a fan of space colonization has a few justifications in mind:

• Living space
• Energy
• Minerals
• Knowledge
• Security
• Romance

The first five are good reasons. The last isn't and we're not going to do the others the indecency of considering it.

• Energy, minerals and living space are proposed as justifications because we look around us and see they're in deathly short supply. Thing is, if you can build a colony on Mars to reduce population pressures, you can build one in the 70% of the Earth still yet to be occupied. If you can build solar panels in space to supply energy to Earth, you can build them in the deserts here. Sure, they won't be as efficient but the transmission losses will be a damn sight smaller and you won't have to drag all the material up there in the first place. Minerals? We're sitting on a twelve-thousand kilometer ball of rock for chrissake. It's a bit quicker to dig a new hole than it is to re-orbit an asteroid, and again 70% of the Earth has yet to have holes dug in it. Sometimes people will talk about how automated factories will make space solar and asteroid mining economical. But if it were to make those things economical, then surely we could pave the Sahara with photovoltaics for next-to-nothing.



• Knowledge. No question about it, we can't find this one on Earth. We want to learn about the solar system, we have to go out there. Except, we don't. People say "oh a robot is great but if you want to do complex science or engineering then you need a human on the ground" well yeah, right now you do. But 20 years from now? Then I'd put even money on those people being wrong. It's a long way off sure and requires a lot of major leaps, but those leaps are dwarfed by the revolutions that'd be needed to make human scientific expedition a more cost-effective option. More, the research needed to make human-equivalent robotic exploration feasible - learning algorithms, complex reactive behaviours, etc - has trillions of dollars behind it, enough to dwarf even the wildest dreams of a second Apollo program.



• Security. When people talk about how delicate Earth is, they're not worried about every living thing on Earth being wiped out, but about society being so disrupted by an asteroid strike/nukes/grb/whatever that the warring remnants finish the job. So the value in an off-world base isn't so much in being off-world as it is in it being self-sufficient and divorced from anything going on at home. But if we can build a self-sufficient community off-world, we can certainly build one here. Except what about making sure it doesn't get wiped out by the initial blast? Well, there're two options: first, your off-world city will have to be meters underground anyway, so you may as well build it underground here. Secondly, may I draw your attention to the exceptional energy-absorbing properties of liquid water. Nuclear blasts are good for all of a few hundred meters in it, and if you're worried about asteroid-induced tsunamis then hell just build one in the Atlantic and the other in the Pacific. Build your colony underwater and not only will it dodge whatever rain of hellfire is consuming the rest of the world, but when things go t*ts up for the colony (which is far more likely than the end of the world) you'll actually be able to reach out and help them.

Anyway, there's my argument. Don't send anyone to their death in the next few decades, send ever-improving robots instead and get the rest without leaving the gravity well. I'm aware this position is in opposition to a lot of very smart people who know a lot more than I do, but I suspect many of them are heavily invested in actualizing their dreams. You don't really go into the space industry for any other reason. The romantic notion I mentioned? I dismissed it out of hand because it can't be rationally argued with, not because it isn't a powerful justification.

Note that none of the above forbids a human-manned Moon or Mars base if you bury it deep enough, it's just liable to end up in the same position as the ISS: cool, but a boondoggle. Anything worth doing you do with specially-designed robots instead. As to full colonies - maybe humans (or our offspring) will eventually be able to thrive off Earth, but it isn't going to happen until we've got flavour-of-the-week "singularity" technologies like compact fusion reactors or super-advanced genetic engineering or mind uploading or strong AI. When you pull those things into an argument, though, you may as well be debating about how leprechauns will help us live on the Moon, so I'm choosing to ignore them. My personal (unfounded) opinion is that Mars is unlikely to ever see a "baseline" human, and the asteroid belt almost certainly won't.

As an aside, if I had Elon Musk's money and arrogance, I'd probably still have similar ambitions. 'First man on Mars' is about as lasting a legacy as you could hope to have.

...

> What about Bigelow Aerospace ?

Bigelow is constructing habitats for low Earth orbit. While that's of course outside the atmosphere, it's still shrouded in 90,000km of magnetosphere that serves to deflect the overwhelming majority of charged particles. Even then though, ISS levels sit at .15Sv/year, which is about a ~1% rate of cancer incidence per annum, cumulative. That's fine for six-month rotations, but colonies? You gotta be kidding. Moreover, put those habitats outside the magnetosphere, and the inhabitants will cook in the first SPE to turn up.