Category Archives: Science And Society

General Science, Science And Society, Space

Free Fall

9 Comments

As Clark notes, here is a very nicely written piece on parabolic flight and weightlessness. Rare is the reporter (even science reporters) who get the physics right on this, because (as he points out) they get confused by the phrase “zero gravity,” which doesn’t really exist anywhere in the universe. Only one quibble:

Each period of ‘weightlessness’ is limited to half a minute or so; otherwise we ‘zeronauts’ would continue freefalling right into the Nevada desert at 600mph. As it is, during half-a-minute’s power- dive we drop nearly 20,000ft – although inside the plane we are completely unaware of this.

This gives the impression that weightlessness only occurs when you “drop” (i.e., descend in altitude). But it actually happens on the way up as well. In both cases, you are “falling” (in the sense that there is no force acting on you other than gravity). First you fall up, then hit the top of the trajectory, then fall down, weightless all the while, and unable to discern your direction of motion. If this seems counterintuitive, it is. But consider an elliptical orbit. As you approach perigee you’re heading down (toward the earth), and once you reach it, you start heading back up (away from the earth) to apogee, but you’re in orbit, and free fall the entire orbit. A parabola in an aircraft is an orbit that, if continued, would intersect the earth’s surface (which is why it is wise to not continue it). And of course, to be more technical yet, it is only parabolic in an approximate sense (assuming flat earth). In reality, it is a tiny section of an ellipse, because the contents of the aircraft are (briefly) in orbit, within the atmosphere.

I should also note that the phrase “power dive” is also misleading. “Power dive” implies that you are diving with engines at full thrust to get down as fast as possible, but in fact, the engines are barely running above idle throughout (until the pullout). Their only function is to overcome wind resistance so that the aircraft can approximate a cannon ball falling in vacuum.

Political Commentary, Science And Society, Space, Technology and Society

Death From The Heavens

26 Comments

Was there a major meteoritic strike 13,000 years ago in North America?

That wasn’t very long ago (compared to, say, the sixty-five million years ago that the Yucatan was hit). Evidence continues to accumulate that we get hit a lot more than people have previously imagined. We really need to develop the capability to do something about it. We have technology in hand to do so, but apparently lack the will to deploy it. This by itself is reason enough to make the investment to become a real spacefaring civilization, but pork and maintaining existing jobs remain more important.

Political Commentary, Science And Society, Technology and Society

Smarter Now?

15 Comments

John Tierney wonders if Dr. Holdren learned anything from his misguided bet with Julian Simon:

Dr. Simon’s victory was not (as some Lab readers suggested) a fluke based on exceptionally lucky timing, as you can see from this Wikipedia graph showing the inflation-adjusted prices for the five metals in the bet from 1950 to 2002. (Since 2002, metal prices rose sharply for several years but have since plummeted back to familiar levels.) Prices do sometimes shoot up for natural resources, but people react by finding new sources and substitutes, and prices come back down. If you look back over the past several centuries, as Dr. Simon demonstrated in his book, “The Ultimate Resource,” you’ll see that the trend was downward long before 1950, too.

What lessons Dr. Holdren learn from that bet? The only one I’m aware of is: Don’t test your theories by betting on them. After Dr. Simon collected his winnings in 1990, he offered to make another bet not just on natural resources but also on any measure of human welfare, like life expectancy or food per capita. Once again, Dr. Simon predicted that humans would adapt to new problems (like global warming) and end up better off in the future — by any measure at any future date that Dr. Holdren or Dr. Ehrlich cared to name. They refused his offer. They did, however, go on making more gloomy predictions and calculations about the problems of sustainability, as in this 1995 essay discussing how to avert future shortages of resources.

I find this particular appointment disquieting. As one of my commenters said earlier, I’d much prefer a “science advisor” who sees technology as a solution, rather than a problem. And, again, I have no idea what the implications of this pick are for space policy.

Media Criticism, Political Commentary, Science And Society, Space

Doing The Right Thing Wrong

21 Comments

Mike Thomas has a misguided rant over at the Orlando Sentinel, bashing NASA and its supposed desire to go to Mars (something that is hard for me to discern, based on what it’s actually doing).

There are, broadly, two classes of NASA critics: those who think that it’s doing the wrong thing, and those who think that it’s doing the thing wrong. I fall into the latter camp, but Mr. Thomas is clearly one of the former. But his position seems to be incoherent. He thinks that NASA is supposed to be doing science (as indicated by his final words), and if so, he’s correct that manned spaceflight, as currently performed, contributes very little to it. But he doesn’t seem to think that it should be engaged in space science. He (like too many) thinks that NASA’s job is to heal the planet. My biggest fear of an Obama administration (at least in terms of space policy) is that they will agree, and divert it from its original role as an agency that looks outward, to one that looks instead inward.

Whether one believes that we should be doing more about climate change or not, Mike Griffin is correct that it is not within NASA’s charter to do the heavy (or even any) lifting in that regard. It was a heartburn that I always had with things like the Ride Report, and “Mission To Planet Earth.” If these are important things to do, then set up an agency to do them, but don’t defocus and distract NASA with them. In fact, it is much more a job for NOAA. The problem is that NOAA has no history of developing satellites, and has traditionally relied on NASA to do it for them. Perhaps that ought to change.

If NASA improperly gets assigned the task of healing the planet, it is inevitable that it will make it even harder for it to properly explore and develop space, which is what it was established to do. Now frankly, given how wrongly NASA has been doing the right thing, I’m not sure that it would be all that much of a tragedy if we were to end its manned spaceflight program. But unlike Mr. Thomas, I’d rather see it starting to do it right.

Science And Society, Technology and Society

Better Climate Control

19 Comments

Through nanotech. J. Storrs Hall (aka JoSH) has some ideas. I have a problem with this one, though:

So you have this balloon and it floats up there twenty miles. They all have a little GPS and receiver so they can turn themselves. That’s all there is to it. What can you do with a machine like this? The machine is essentially a programmable greenhouse gas. If you set the mirrors facing the sun, it reflects all the sunlight back. If you set them sideways, it allows the sunlight to come through, and similarly for the longwave radiation coming from the back side of the earth at night.

He seems to be implying that GPS can be used to determine attitude. It can’t. It only provides velocity and position. Now it may want to know that information for other purposes, but there will have to be some other means of attitude knowledge. It seems to me the simplest way would be to just measure the sunlight hitting the mirror (which would actually be a solar cell). As you adjust your attitude, the power available will grow or shrink, and it can use the rate to control the angle. As for how to physically control the attitude, I would guess that little reaction wheels would do the job.

Of course, many of the warm mongers hate technical solutions like this, because they don’t require us to piously tighten up our hair shirts, and they don’t allow for sufficient control of the global economy.

Political Commentary, Science And Society, Space, Technology and Society

The New “Science” Advisor

16 Comments

Ron Bailey has some background on Dr. Holdren.

I put the “science” in quotes, because I’ve always thought the position misnamed. It’s really about science and technology (as indicated by the name — the Office of Science and Technology Policy), and the science advisor should also be a technologist, not just a scientist. Either that, or get a different and separate advisor for technology. When you put a “science” advisor in charge of providing advice on NASA, it reinforces the false perception that NASA is primarily about science, which results in all manner of policy ills.

In any event, I hope that Dr. Holdren has modified his environmental views from the seventies, and no longer allies himself with Paul Ehrlich.

[Mid-afternoon update]

Yuval Levin has more thoughts and concerns:

Perhaps more striking is his activism well beyond his own academic specialty, arguing, for instance, that scientists have a responsibility to advance the cause of the elimination of all nuclear weapons and seeking controls on population growth. And he didn’t say all this in the 1970s either—have a good look at the speech he delivered when he assumed the leadership of the AAAS in 2006. It describes a fundamentally activist liberal mentality about the very purpose of science and its place in our kind of society. My favorite part of that speech is his call for ending population growth which, in the published text of the speech, is accompanied by this footnote:

This was the key insight in Paul Ehrlich’s The Population Bomb (Ballantine, New York, 1968), as well as one of those in Harrison Brown’s prescient earlier book, The Challenge of Man’s Future (Viking, New York, 1954). The elementary but discomfiting truth of it may account for the vast amount of ink, paper, and angry energy that has been expended trying in vain to refute it.

The Population Bomb was the book in which Ehrlich predicted that “in the 1970s and 1980s hundreds of millions of people will starve to death,” because all the world’s resources were running out while population was growing out of control, and there was simply no way we could sustain our civilization at modern levels of consumption and growth. Just about every one of the book’s predictions has proven wrong, and its empirical claims and methods have not held up well under later scholarly scrutiny. It certainly made a useful political point for the left, though.

I wonder if all those who complained about the supposed “politicization of science” by the Bush administration will raise worries about Holdren…don’t you?

No, actually, I don’t wonder at all. I think we know the answer to that one.

[Bumped]

[Update a few minutes later]

Here’s more from John Tierney:

Does being spectacularly wrong about a major issue in your field of expertise hurt your chances of becoming the presidential science advisor? Apparently not, judging by reports from DotEarth and ScienceInsider that Barack Obama will name John P. Holdren as his science advisor on Saturday.

Dr. Holdren, now a physicist at Harvard, was one of the experts in natural resources whom Paul Ehrlich enlisted in his famous bet against the economist Julian Simon during the “energy crisis” of the 1980s. Dr. Simon, who disagreed with environmentalists’ predictions of a new “age of scarcity” of natural resources, offered to bet that any natural resource would be cheaper at any date in the future. Dr. Ehrlich accepted the challenge and asked Dr. Holdren, then the co-director of the graduate program in energy and
resources at the University of California, Berkeley, and another Berkeley professor, John Harte, for help in choosing which resources would become scarce.

In 1980 Dr. Holdren helped select five metals — chrome, copper, nickel, tin and tungsten — and joined Dr. Ehrlich and Dr. Harte in betting $1,000 that those metals would be more expensive ten years later. They turned out to be wrong on all five metals, and had to pay up when the bet came due in 1990.

I hadn’t realized that there were other bettors besides Ehrlich, or that Holdren had made the pick. To be honest, I had never heard of the guy until Obama named him. So now we shift from a “Republican war on science” to a “Democrat war on science.” Or, perhaps, a Democrat war on the economy and freedom in the ostensible name of science. And I have no idea what this portends for space policy.

[Late afternoon update]

“Solve Climate” has an extensive set of Holdren links. I sure hope that he at least gets some tough questioning in confirmation hearings.