A long-time goal of space enthusiasts is about to reach fruition–the first solar sail is about to take flight. The really neat thing about it, to me, is that it’s privately sponsored. I remember discussing this at dinner in 1982 with Rob Staehle, the JPL engineer who was planning the project that long ago as an extra-curricular activity (more recently, he was the pre-project manager for the Pluto Express mission and is now the Deputy Project Manager of the Europa mission), and it’s great to see it finally happening.

To the degree that many people are aware of the concept of solar sails, they mistakenly believe, taking the nautical analogy, that they are blown by the solar wind. But solar sails, or light sails (the more generic term, because they could be powered with lasers as well as the sun) actually get their thrust from radiation pressure. The solar wind is composed of heavy, highly-energetic particles that would blow right through a sail, destroying rather than propelling it. The sail is instead impinged by photons, the components of light.

The article linked above says that the sail absorbs them, and gains their momentum, but if this occurs, it’s actually less efficient. Ideally, the photons actually reflect off the sail, imparting twice the momentum that they would if they were absorbed. Thus, a well-designed sail has a mirrored surface, or at least a surface that acts as a mirror for the frequencies of light for which it’s designed. Also, since the lighter the vehicle, the greater the acceleration for a given force, it’s made as thin as possible while still maintaining structural integrity. Finally, since force is pressure times area, the bigger the sail, the more thrust can be attained.

Because the solar radiation pressure is so small, even for a large sail, the total force might only amount to a few pounds. But if that’s the only force acting (other than gravity), it can still add up, and with continuous acceleration, get you to an outer planet faster than chemical propulsion.

One question often asked is, if the radiation pressure always acts outward from the sun, how a sailing spacecraft can come back into the solar system. Answer: like conventional sailing ships, it tacks (though the analogy is imperfect–being in a vacuum, unlike the water for a ship, there is no medium in which it travels, and it thus has no use for a keel).

Imagine that the sail is at an angle with respect to the sun. Some of the thrust is directed radially along its orbit. Add to orbital velocity, and the energy increases, and the sail heads out to the outer system. Change the angle to subtract from it, and the sail will slow, and fall back in toward the sun. Angle it out of the orbital plane, and you can slowly perform a plane change.

If we really did want to drop nuclear waste into the sun, a sail is probably the only affordable way to do it, with the additional advantage that as the star is approached, the thrust increases as the square of the distance (twice as close means four times the thrust). Unfortunately, because they’re such delicate things, the sail might burn up before it had decreased its velocity sufficiently to drop all the way. So a final booster rocket might still be needed.

Here’s an extremely little-known fact. Solar sails played a significant role in the conceptualization and development of nanotechnology. Back in the 1970s, a young student at MIT, enamored with space, was trying to figure out how to develop the minimum thickness for a sail. He came up with a concept for laying out an ultra-thin layer of aluminum on a wax, using a technique called vacuum-vapor deposition, in which the metal would be heated to a vapor, and sprayed on a substrate in a vacuum chamber. Afterwards, the wax would be melted away, leaving the thin aluminum foil. He reasoned that he could get a sail that was only a few atoms thick–strong and reflective enough to be a good sail (as long as it was handled properly) while providing maximum performance.

One thing led to another, and he eventually came up with other techniques for building things at atomic-level scale, and gave some serious thought to the implications of such manufacturing. He wrote a book on the subject in the mid-1980s, and eventually, in 1991, received the first doctorate in the field, having played a major role in inventing it, from MIT. His name, of course, was K. Eric Drexler.

If you don’t already have plans for Memorial Weekend, and you have the time/money to get to Denver, and are interested in space, you might want to consider attending the International Space Development Conference, sponsored by the National Space Society. I’ve been to many of these, and you’ll find programming to suit every taste, from whiz-bang technologies, to recent results in space science, space law, and discussions of asteroid mining, colonization and settlement. It’s probably the largest gathering of space enthusiasts you’ll find during the year.

Don’t miss it if you want to find out the latest in our progress to spread life into the universe.

The Sixth Circuit Court has reversed the lower-court decision, and ruled that the University of Michigan Law School can practice racial discrimination (my interpretation of the ruling). It was a narrow ruling, five to four. What’s most interesting to me is not just the dissent, but the fact that some of the dissenters claim that the majority is not only wrong, but that they cheated procedurally.

I’m no lawyer, but the arguments for the majority read pretty strained to me. This is why the Dems are fighting so hard to keep Bush from putting judges on the bench. They know that the majorities for their nonsense is thin.

This one’s almost certain to be appealed. It will be interesting to see if the USSC takes it.

Alan Boyle has set up a weblog over at MSNBC, covering space and science stuff. It’s off to a good start–right out of the gate, he permalinks to Paul Hsieh, NASA Watch, me, and Jay Manifold, among others.

I notice that MSNBC has put up a disclaimer, though–they disclaim responsibility for internet links. You’d like to think that goes without saying, but unfortunately, it doesn’t.

Here’s yet another good article on the insane stupidity of zero-tolerance policies.

Between this, and the recent stories about the abysmal (and I believe deliberately-planned) ignorance of history among students, the state of our public school system is absolutely frightening. I see it as fundamentally conceptually flawed, and beyond any hope of reform.

Yet another reason for disappointment in Bush. I can only hope that the current federal education nonsense is a maneuver to set the stage for reversing things in a second term, but I see little reason to hope.

Lileks is beating up Patch Adams with a verbal truncheon. Is nothing sacred? Could it be more politically incorrect?

It’s wonderful.

If you knew your doctor was a clown, you?d find another doctor. You don?t want to be given the biopsy results by someone with a flowerpot on his head. You don?t want your doctor to demonstrate the effect of chemotherapy on a tumor by sweeping up an ever-diminishing spotlight. God forbid you should wake up during the operation and see your doctor pulling yards of knotted scarves from your abdomen.

People who are clowns are telling you something and you?re a fool not to heed them.

There’s an article over in Wired about backyard experimentation with anti-gravity devices.

Keith Cowing over at Spaceref (and NASA Watch), has some good thoughts this morning on how to make lemonade out of the lemon that is the International Space Station. I don’t agree with it in entirety, but it’s definitely worth a read.

I was going to write up a report of my trip to the Space Access Conference, but my friend Leonard David has beaten me to it.

It is the belief of a corps of 21st century crusaders that getting up into space requires less of a down payment than ever before. There’s been a reduction in development time and risk to build vehicles able to offer routine, cheap access to space. Lastly, it appears that a flourishing of non-traditional space markets is near at hand, Vanderbilt said. “All this seems to be converging on a spot where the business case for these ventures makes sense,” he said.

Over the decades, pushing spacecraft into orbit has primarily meant taking the “disintegrating totem pole” approach, said Clapp of Pioneer Rocketplane. Critically needed are true spaceships that fly “real high, real fast, and real often,” he said.

At days end, it remains the thrill of space flight that stirs the soul, Clapp added. “It’s almost as if we all share this religion?this enthusiasm for doing something in space. It?s a passion that people who are very religious, I think, would understand.”

Clark Lindsey at Hobby Space has a good review as well.

My Fox News column got some email response, which regurgitated the standard conventional “wisdom.”

Stephanie Crowe writes:

You make a point that if pilots were not needed Fed Ex would not be using them. I think that there are a few issues that keep pilots flying Fed Ex Planes. a) liability risk, b) unions, and c) pre and post flight taxiing.

Well, no. The primary reason is that the FAA requires it, and if you ask Fred Smith, I think that he would himself be leery of roboticizing his aircraft, regardless of what the union thinks.

I will agree somewhat with (a). To the degree that liability risk is there, it’s because it’s a real risk. There’s no evidence that a totally-automated aircraft would be safer, from a third-party standpoint, than the current system. There may be some time in the future in which that becomes the case, but it isn’t even in sight right now.

For NASA the liability risk is small as all flights are over water.

This is irrelevant because a) the proposed vehicle will not (necessarily) be operated by NASA (and if it is, it’s unlikely that it will operate much more cheaply than Shuttle, so there’s no point in spending billions of dollars developing it), and b) there’s no reason to suppose that it will only operate over water. Finally, this argument utterly ignores the fact that reliability is very important in a reusable vehicle, regardless of what’s happening on the ground below–these things will be expensive. Anything that can enhance it (including the use of human pilots) will be employed.

There is however a considerable “union” pressure from the astronaut corps to keep piloting crafts (I am reminded of a scene from “The Right Stuff” where the engineers are calling the vessel a capsule and the test subject are calling it a space craft). Taxing has never been an issue with space going craft. Unmanned rocket payloads have always had automated flight paths and the current Space Shuttle is effectively automated during launch. People are foolish (as a group) and like to see a person “in control” regardless of his actual authority.

Even if such a desire is “foolish,” the desire remains, and so will the pilot, if the vehicle is to be used as anything other than a Shuttle replacement. If it’s to be used only as that, then it’s a huge waste of money.

I agree that using a man safe certified system for ferrying cargo is foolish and I am glad it was stopped for whatever the reason. I have always though that there should be a three level certification process for space systems something maybe like this:

Shuttle is not a “man safe certified system.”

Man certified – capable of carrying human cargo (probability of failure 0.999999 or 6-9’s, although the current STS only has a demonstrated probability of failure of 0.99 or 2 9’s).
high value certified – capable of carrying high value instrumentation
(3-9’s)
low value certified – capable of carrying low value instrumentation,
fuel, food, …. (2-9’s)

Again, all of your “certification levels” (which currently don’t exist in any form, other than man rating, which is irrelevant to the current discussion–see this post which is the full-length version of my Fox News column, and expands greatly on this very subject), totally ignore the value of a reusable space transport itself. Hint: think hull insurance.

Robert Engberg writes:

I beg to differ with the notion in your article “Look Ma, no pilot” that a piloted vehicle would lower the cost and be more reliable than an unpiloted one. Ariane 5 is curently the most cost effective launch vehicle to place a satellite in LEO. It is entirely automated.

Note that he brings up an entirely irrelevant example. Ariane V is an expendable launch system. Putting a pilot in it would either increase costs tremendously, or it would be an oxymoron, unless the pilot were a kamikaze type. It doesn’t bring anything back, so it’s nonsense to talk about piloting it. The fact that it’s the most effective (that’s only because its development was subsidized largely by the French government) doesn’t make it good in any absolute sense. The reason that SLI exists is to, ostensibly, dramatically reduce the cost of access to orbit, and eventually put things like Ariane out of business.

As were every scientific space probes to all the planets in our solar system.

Again, this example has zero relevancy, for the same reasons. It was unaffordable to put people on those probes (though we’d have no doubt learned much more if we had). The argument isn’t that automation can’t be done, if essential–it’s that it’s not the best way to operate a reusable transportation system.

And with the exception of docking, lowering the landing gear, and deploying the drag chute, the space shuttle can launch and land automatically.

Yes, it can. And the Shuttle costs half a billion dollars per flight. I’m not arguing that we can’t build a fully-automated space transport. I’m simply arguing that this is not the road to low cost, as his examples demonstrate much more eloquently than I could.

Even the cash strapped Russians had an automated launch and landing of their version of a space shuttle back in 1988. No cosmonauts.

That’s because they made the mistake, taking NASA’s lead, of building an all-up system with no incremental flight testing. Again, cash-strapped or not, the system was ultimately unaffordable. That suggests that they may have made a bad design decision in building such a thing in the first place (which was largely a copy of the Shuttle).

With astronauts and pilots, they of course require training, salaries, etc. not to mention the added complexity of environmental, control, and life support systems to the launch vehicle. The automated GNC technology for launching and landing spacecraft has been around for decades.

These are not significant expenses in the context of the total program. And the automated GN&C technology for taking off and landing aircraft has been around for decades as well. But for some reason, those philistines and luddites at the FAA and the airlines still insist on putting pilots in the cockpit. The airliner industry is extremely mature, but they still think pilots are important. But you argue that in a new type of vehicle (a reusable space transport), never successfully built before, that we can do without them. What’s wrong with this picture?

As such, the reasons for having a manned (sorry, “crewed”) launch vehicle are more political and psychological than technical and economical. Who would have really cared if a lunar probe had landed on the moon?

More irrelevancy. We’re not talking about humans as payloads–we’re talking about humans as pilots of vehicles that you want to get back, routinely and reliably.

(Actually, it already had by the time Neil Armstrong stepped on the lunar surface.) As for Fed Ex wanting automatic planes, well, Fed Ex is not in the risky, expensive business of developing commercial aircraft. Most commercial aircraft business is to airlines, which carry passengers, and not many passengers would want to fly in planes with no human pilot.

Yes, and they will want that even more in something as unfamiliar as a space transport.

Even flight attendants were originally put in planes by airlines to attract more male bread-winner passengers, since if they saw young women flying in planes, they reasoned that it must be pretty safe.

Yes, and much the same thing will happen to sell space passenger travel.

Earth to orbit flight is one of those things that for now is barely possible.

Nonsense. It’s routine. The only thing that’s difficult is doing it affordably, because very little effort has gone into developing markets large enough to make that possible.

The main challenges are finding a suitable energy and propulsion system and developing suitable materials that can survive such extreme changes in aerodynamic loads and temperature.

No, the main challenges are overcoming stale Cold-War notions like the ones above, and raising the financing for a viable commercial vehicle. And my prediction is that when this occurs, it will be piloted. The technology is the easy part.