Monthly Archives: August 2010

Politics

Build the Community Center

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I don’t often put up posts about non-space politics on this blog, especially now that I have a smidgen of internet fame to my name. However, there’s something going on now that is both important and something I feel strongly about. I’m talking about all this manufactured controversy in the punditry surrounding the Islamic community center in New York City, and I am putting this post up because I strongly support the center’s construction. I have three main reasons for supporting the community center.

Reason numero uno is that there is no rational connection between this community center and the terror attacks of 9/11. Protesting its construction is pretty much equivalent to protesting the construction of churches south of the Mason-Dixon line because the KKK used to lynch people down there. The protesters and pundits are committing the logical fallacy of the sweeping generalization: the 9/11 hijackers were Muslim, therefore all Muslims are potentially to be feared. This is an extremely dangerous attitude, and it brings me to…

Reason number two: I was raised Jewish. My temple Hebrew school curriculum devoted a full year to education on the dangers of bigotry, prejudice, and otherwise singling out any ethnic, racial, or religious group. Certainly, that education focused on the experiences of Jewish people, but the lessons we discussed were broadly applicable. I have internalized many of my experiences from growing up and living as a member of a cultural minority, and I respect the needs for other minorities to practice their beliefs and gather as a community. Such things should not be made unpleasant by the actions of the cultural majority. More than that, the cultural diversity of our country should be celebrated – it is what makes us great!

It’s very easy for hate speech to come out of this, as the protesters stir up emotions. After all, their entire argument is based on emotion: even when the pundits backpedal as hard as they can to avoid sounding bigoted, they end up calling the community center’s location things like “tasteless” – forgetting that, in this sense, “taste” varies from person to person and is based on emotional responses. Even such mild-seeming criticism can lead to prejudice and bigotry. Now, I’m certainly not saying that I think the United States is on a slippery slope to an imitation Holocaust. I don’t think that is true at all. But I know that pogroms and bigotry happened well before that, and what some of the protesters are saying while assembled in a mob near the Islamic center makes me nervous. As a Jew, when I say “never again,” I don’t just mean myself.

Reason Number Three is that I am an American. I am patriotic. I believe in the American system of government and American ideals. I also think about those ideals. The founders of this country were products of the Enlightenment and the internecine prejudices of Europe; they were wise enough to know that their new country should be established without a single state religion and with built-in acceptance of all the various faiths in all the original thirteen colonies. (Remember that, in those days, the various strains of Christianity were considered as disparate and irreconcilable as Hinduism and Judaism. The colonists came from a Europe that periodically tore itself to pieces over differences between Catholic and Protestant groups – and that was between faiths that agree on basic things like who’s a god and who isn’t!) If the framers of our Constitution had wanted America to be a Christian nation, I’d think they would want to be much more obvious about it, to make sure that their intentions were clear as time passed: while Judeo-Christian philosophy certainly influenced the Constitution, that document contains exactly zero references to God, Jesus, or Christianity.Nor does it refer to any other religion.

Even a general lack of endorsement of one religion over another wasn’t enough for the newly founded states, though. Think back to high school history classes: the states refused to ratify the Constitution before the inclusion of a Bill of Rights, and the very first amendment that they demanded specifically prohibits the federal government from establishing a state religion. Not only that, but it grants individuals the right to practice any religion they like, and to assemble together for any purpose, including practice of religion. So not only is the community building this Islamic center well within their rights to do so, but we ought to celebrate what they are doing – they are exercising rights that do not exist in many countries but that we, as Americans, gladly extend to our citizens. We ought to give thanks to the founders of our country and the legislatures of the original thirteen colonies for giving us so many rights, rather than protesting the exercise of these Constitutional rights!

As a final note, let me mention that other supporters of the community center include the mayor of New York City and the families of 9/11 victims. You know, the people actually affected by the presence of the community center, and the people most likely to have a negative emotional response to it. The pundits on Fox News are using the Islamic center as a political football to try and drum up support for reactionary candidates, and I think they ought to be ashamed of their actions. Not only do they come across as prejudiced, but they seem very un-American to me. Of course, this is America – so they can keep right on saying what they’re saying. That’s one of the sticky points about any debate like this. At the very least, though, I can hope that with all the information available out there, the general populace will think critically about what’s going on before succumbing to emotional reactions.

Concepts, Geology, Science, Science Fiction, Space

The Ice Fracture Explorer

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Europa, the second Galilean moon of Jupiter, has been my favorite planetary body for a long time. The reason I like Europa so much is that it’s a world whose orbital dynamics with Jupiter, its orbital resonances with the other Galilean moons, and its own rigid-body dynamics have a strong hand in creating its surface features – and giving it the potential to harbor life. It’s one of perhaps two or three extraterrestrial places in the Solar System where we might hope to find life. Europa is also easier to get to than Enceladus or Titan. As such, I think it ought to be one of the highest-priority exploration targets for robotic space probes. (Human exploration would be nice, too, but if you think radiation exposure on the way to Mars is hard, you don’t even want to consider putting people in the Jovian system!)

Thanks to magnetometer measurements and images from the Galileo mission, it’s pretty much established at this point that Europa has an icy outer shell over a global liquid ocean, with a rocky core on the inside.* The only question is how thick that ice shell is – I’ve read estimates ranging from 10 meters to 100 kilometers, with a pretty high confidence of ones to tens of kilometers. The ice shell gives rise to a number of interesting surface features. A particularly cool sort of feature, found with global extent across Europa, is the double ridge.

A prominent double-ridge feature on Europa, most likely a crack in the icy shell

Planetary scientists have a number of models for how these double ridges form, and they generally seem to agree that the ridges mark the locations of cracks in the ice crust. One especially well-established model suggests that these cracks occur when Jupiter raises tides in Europa’s ocean – just like how the Moon raises tides in terrestrial oceans, but much stronger, because Jupiter is frakking huge compared to Earth’s moon. Europa’s ice crust bulges out over the ocean’s tidal swell and then cracks under the incredible stress. (I like to take a moment to think about the mindbogglingness of that statement: the whole moon’s surface cracks. I’ve stood on a frozen pond when a crack pings through the foot or so of ice on top of the water – Just imagine standing on Europa when this happens!) Once a crack forms, the tides don’t go away. As Europa rotates, about once every three and a half Earth days, the tides periodically lever these cracks apart and squeeze them back together again. In this model, every time the cracks gape open the subsurface ocean gets exposed to space. The surface water boils and rapidly crusts over with ice, and when the cracks get smushed closed, all this ice gets crushed up and forced to the top and bottom of the crack, forming the ridges. The ridges appear in pairs because the crack opens up again after that. These double-ridge features are mounds of crushed ice flanking passages into Europa’s ocean!†

Dr. Richard Greenberg is a planetary scientist who thinks that these cracks in the ice shell might be potential sites for life to take hold. Unlike the rest of the subsurface ocean, they get exposed to sunlight, which means that photosynthesis could take place. The periodic in-and-out forcing of the crack would also drive strong currents, which is another energy source Europan life could use. (Those aren’t the only energy sources: other possibilities include thermal gradients in the water, volcanic vents on the ocean floor, or even induction as Europa travels through the Jovian magnetic field.) Of course, that life would also have to adapt to the crack opening and closing once every 3 1/2 Earth days!‡

Europa's possible ice-fissure biosphere (from New Scientist; click for full article)

We do at least know, from the Galileo mission, that these cracks often have accompanying veneers of organic (e.g. carbon-based) molecules and salts splashed onto the ice surface. This is why the cracks appear as brown stripes in large-scale context images. The crack/veneer combination suggests that there are organic molecules and salts in the Europan ocean, and that those compounds get pumped to the surface through these cracks.

So, let’s take stock: Europa is the only extraterrestrial world with a global liquid water ocean, there is a definite possibility for life in that ocean, and these double-ridged cracks are a possible gateway into the alien biosphere.

Well, then, let’s go diving! Read on for my concept system architecture for an ambitious Europan ocean-exploring mission, which I call the Ice Fracture Explorer.

Continue reading The Ice Fracture Explorer →

Graduate school, Research, Science

My Presentation Philosophy

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Hello again, Blogosphere!

I spent last week in Toronto at the annual AIAA Guidance, Navigation, and Control Conference. This is a huuuuuuuuuuge conference of engineers from academia, military, and industry all presenting papers about their research. So, I got to see a lot of Powerpoint presentations. (Okay, okay, supernerds, there were some PDFs and Keynotes. But “Powerpoint” is pretty much like “Kleenex” these days.) And an awful lot of the presentation slides I saw looked something like this:

Fine, right? I mean, this is a technical venue, full of super-brainy engineers. We want the facts, ma’am, just the facts, in all their glorious mathematical detail, and style means nothing. Right?

WRONG!

The first rule anyone will ever tell you about giving any kind of presentation is to know your audience. And if I’m in the audience at a conference like this, then I’m spending a full day listening to technical talks and you have only twenty minutes to make me think that your research is as cool, interesting, or relevant as the title made it sound when I picked it out of the lineup that morning. Because I’m still holding the conference program in my hand, and I have a notepad and pen ready to jot down research ideas the last cool presentation made me think of, and I might have my laptop in my bag, so I’m not at a loss for things to do if you’re not very exciting. In other words, not only do you need to convey your technical material, but you also need to keep me interested and/or entertained, at least enough to keep me listening to your technical stuff.

It’s a tall order.

I’ve been told that I do a good presentation, though, so I’m going to share a bit of my philosophy for what a technical presentation should be like. Here are the points that I start from:

  1. Nobody wants to see lots of equations. Some are necessary, sure, and they can be a great way to add technical gravitas, but a 20-minute presentation is a much better time to show off results, pictures, movies, hypotheses, conclusions, possibilities, tricks, and excitement. And if the conference is like GNC, requiring a paper with each presentation, then all the equations go in there, anyways. The oral presentation is for highlights, not derivations.
  2. These presentations come in the middle of a solid block of otherwise identical presentations that are going to blur together in the audience’s minds. So, they need to be distinctive. In other words, a bit of flash and polish goes a long way. Also, attention-grabby things like pictures and movies are good, but not if they’re just thrown together in a clip-art sort of way. (There’s good attention to grab, and bad attention to grab!)
  3. Slides are visual aids. I mean both “visual” and “aids.” Think about both of those terms: slides are supposed to be for showing the audience things. And the slides in a live presentation are not supposed to be completely independent of the presenter: you should refer to them, but you are the one giving the presentation.

As an example of my own style, allow me to go through my recent GNC presentation slides and point out my thoughts on their layout, style, and content. If you want to follow along, most of the presentation itself is here on YouTube:

Continue reading My Presentation Philosophy →