RATS is a program in which NASA engineers, scientists, and astronauts take prototype equipment into remote locations on Earth and practice the procedures and operations that they would use if they were actually on another planet. It’s an opportunity for the engineers to see what their creations are capable of, scientists to see how much work astronauts can get done and teach them basic skills like field geology, and the astronauts to get some experience using the equipment so they can provide feedback.

Not only is RATS showing off the best capabilities of the most successful part of the Constellation Program – the Lunar Electric Rover Concept, or LERC – but they have gone to an especially cool site, a well-preserved but little-known cinder cone volcano known as SP Mountain! As that video played, I kept thinking to myself: “that looks familiar…” Here’s my view of SP and the lava flow coming out of the base of the mountain:

SP Cone

SP flow

When I was there, with a class of planetary geology grad students led by Cornell Mars scientist Jim Bell, I couldn’t help but picture the rugged a’a terrain of SP flow with astronauts picking their way along. What a tremendous place to practice exploration operations!

Grad students exploring the flow

Since last February, I have been trying to get my sci-fi short story, “Conference,” published. So far, the score is 0 for 4.

Asimov’s Science Fiction sent me a form-letter rejection.

The Magazine of Fantasy and Science Fiction sent me a personalized letter. The editor wrote that “this tale didn’t quite work for me, I’m afraid,” and thanked me for sending it along. I appreciated the thought, at least.

Analog Science Fiction and Fact sent me a two-page form letter containing, basically, their submission guidelines. The editor scrawled a note at the bottom in blue pen, though: “PS: Present-tense narration tends to call excessive attention to itself and is generally best avoided unless a particular story requires it.”

I just heard back from Strange Horizons. They sent a short note that said thanks, but they decided not to publish the story.

I happen to really like this story, and I’d love to see it published. It takes place in the Cathedral Galaxy, a universe I hope to expand with many more stories, but it grew out of my experiences as a grad student. The mundane bits of researcher life. Giving a presentation to a research community. Camaraderie among grad students. Taking advantage of conferences to go sightseeing – and grinning at the crowds of other scientists doing the same. Research advisors, good and bad; on-the-ball and absent-minded. Having different impressions of a scientist from reading their papers and from actually meeting them. Reacting to the presence of the “big names” in a particular field. Even finding love within a technical community – though it certainly didn’t happen to me the way it happened to Ceren Aydomi.

So, readers, since I like this story so much, I’d like to workshop it a little. If you can, take a look. Is it too long? (It’s almost 10,000 words, which is on the big side for a short, but when I read it, it doesn’t feel too bad to me.) Does the present-tense narration bother you? Is the action too slow or too fast in places? Are the characters strong enough, and do they interact naturally enough? If you’ve been to a research conference before, how does this feel as a depiction?

I’m all ears!

As I mentioned above, I’m an amateur at the beer review process; but at least this is my 3rd Brew Fest, I like trying things, and I can make a stab at putting some of my thoughts into words. Here are some of the highlights that stand out in my mind after Brew Fest 2010:

Ithaca Beer Co.: CascaZilla and Cold Front

We are fortunate to have a really good brewery here in town, and I’ve just got to bring them up first. My friend was especially a fan of CascaZilla, IBC’s red ale. It’s a nicely balanced beer, between hoppiness and maltiness. At my insistence, our first tasting of the day was the Ithaca Beer Co.’s Cold Front, a Belgian-style amber ale. I first tried Cold Front at last year’s Brew Fest and it rapidly became my favorite beer of the fall and winter. It’s got a complex combination of several smoky flavors and gives me a very nice warm-and-fuzzy-inside feeling. Goes wonderfully with pizza from The Nines in Collegetown, or a Guinness burger at the Ithaca Ale House!

Weihenstephan: Korbinian

Weihenstaphen is from Freising, Germany and has been in business since 1040 C.E., so we kind of figured that they probably knew what they were doing! Korbinian is a doppelbock – which is, I think, my favorite kind of beer. Korbinian was particularly caramely and chocolately, with a strong, delicious smell to it. It was a very heavy beer – not really bready, but still not the kind of thing you can just drink; you have to take it in sips. We tried to come back for seconds on this one!

Wagner Valley Brewing Co.: Sled Dog Doppelbock

We continued a round of dark beer tastings with another doppelbock, the Sled Dock from Wagner (a NY local). This doppelbock was second only to the Korbinian, I thought: it also had rich caramel flavors, though it felt a bit lighter, making it easier to drink in larger sips.

Anchor Brewing: Anchor Porter

I do like a good porter, and this one hit the spot: a nice, rich, dark porter; a bit more bitter than all the doppelbocks we tried.

Here we are with the Anchor Steam Porter: it had the perfect color for a Brew Fest photo!

Bellwether Hard Cider: Liberty Spy and No. 4

Bellwether overcomes the disadvantage of its owner’s amHerst College heritage to produce some very tasty hard ciders, and is the establishment that introduced me to fine hard cider on par with all the craft breweries and many upstate NY wineries. I prefer their Original and Liberty Spy hard ciders to the fancier things like Cherry Street and Black Magic, which get augmented with cherries or black currants. Liberty Spy has clear apple flavors coming through; it’s fruity without being too sweet. New to me this year was No. 4, which had more sour-apple notes. Tasty without the flavors being overpowering!

Brewery Ommegang: Abbey Ale and Kup O Kyndnes

Ommegang’s Abbey Ale is brewed in the Trappist style; it’s got a lot of strong brown-ale flavors without being as chocolate- or caramel-dominated as the doppelbocks. Ommegang is a regular and Abbey Ale was a Brew Fest favorite among most of the people I talked to; it topped my friend’s list enough that he said he’s going to make a point to look for it back where he lives in the Boston area. That brew is something to be careful of, though: it’s delicious, but over 8% ABV! I tried their Belgian-style Scotch ale, Kup O Kyndnes, for the first time this year, which successfully combined a number of flavors from other beer styles.

Flying Dog Brewery: Raging Bitch

Whoo! This was the most punch-in-the-faceiest hoppy beer I have ever had. If you like hops, you should try it. It was definitely not my favorite, but I mention it because some people like their hops.

Roosterfish Brewing: Hop Warrior

Roosterfish’s imperial IPA is an extremely hoppy beer, rating 120 IBUs (whatever those are). However, what distinguished it from the Raging Bitch was that its full-on hoppiness was very well balanced out with malts, making it much easier to drink and giving it a full-bodied flavor. It compared nicely with Ithaca Beer Co.’s CascaZilla red ale, only more so.

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:

General Style

I think slides should be spartan. It’s not just that I’ve been lately trending towards minimalism in design – but it also bears thinking about exactly what information you think is important before you put it on a slide. The pictures, equations, and bullet points you select should be put on the slide to draw attention to them, and the slide should not include all sorts of accoutrements and fancy design stuff that distract from the actual content. I like to start all my slides from a “blank” template, and view them as an empty space which I can use to set off the things I want to talk about rather than trying to fill them with content. In general, I like to make slides that don’t include any extraneous information. (For example, everyone in the audience already knows what conference they are attending and what the date is. Not including the standard Powerpoint footer bar could buy you about 10% more slide space to work with.)

There are some things that technical audiences expect to see on each slide, and I’m willing to make some concessions here. For instance, many people expect some indications showing where this slide fits into the presentation, such as slide numbers. This serves two purposes: first, to give the audience a sense of how the “story” is progressing; and second, to give them something to refer to during the Q&A after a presentation. I also think it’s good to include some mark on each slide identifying yourself, such as a university logo or whatnot, because that helps drive home your technical “street cred.”

Finally, for years I have strongly favored dark backgrounds and light text or graphics. I do so for a simple reason: when projected against a wall in a dark room, light colors can look especially bright and sometimes seem to glow a little. Take an example with 100% black and white backgrounds and text, and with the same glow filter applied to the white parts. Clearly, the text in the top half of the image is not 100% black any more:

Which looks clearer? Which text stands out more?

There are two ancillary bonus features for me in going to a white text/black background scheme. One is that I talk about space, and it helps to make my slides more space-y. Two is that not many people go for a black background, so it helps to make my presentations more distinctive, standing out in the audience’s minds. (Three presentations from my research group were the only ones I saw at GNC that had a black background.)

Title Slides

I think of the title slide as my opportunity to anchor my audience with my premise, and my last chance to catch someone wandering from session to session. So I want flashy stuff, and I want that stuff to connect with my title in such a way that it gives the audience some more insight into what my title keywords mean.

So, here, I have my paper title, authors, and affiliations, but I leave off the name of the conference, session title, date, or any other text. The title slide is not the place to make a point, and again, I presume my audience already knows where they are. My graphic, showing a modular spacecraft in various stages of unfolding, hints at what I mean when my title says “multibody spacecraft reconfiguration,” and the view of Saturn is just plain cool – and hints a little that I’m thinking about far-flung applications.

Here’s another thing I don’t do on my title slides: I don’t start my presentation by saying, “Hi, I’m Joseph Shoer, and I will be presenting on Simulation of Multibody Spacecraft Simulation through Sequential Dynamic Equilibria.” Why? Because my session chair just introduced me with exactly those words. I don’t need to repeat, and I don’t need to read off the slide – presumably my audience can do that for themselves. I say, “Thank you for the introduction,” and then I start right in.

Outline Slides

Engage rant mode!

The vast majority of technical presentations I’ve seen include an “outline” or “agenda” slide. In general: I hate them.

I hate outline slides because they either convey no information I didn’t know already, or they convey very specific information that is entirely out of context and so I don’t understand it yet. Either way, they are a waste of time. In a 10-, 15-, or 20-minute presentation, saving thirty seconds to a minute can be quite important.

The outline slides that convey no new information have a bullet list that says something like Introduction, Background, Methods, Data, Results, Conclusions. You know, some variation on the standard lab report headings. If I’m listening to a presentation, I already know that you’re going to have an introduction and conclusion, and I already know that there’s going to be some kind of content in the middle. And if I’m at a technical presentation, then I already know that the middle sections involve explaining some experiment or model, looking at data, and extracting results. On top of the slide itself, one rule of presenting is that the speaker should talk about everything that appears on the slide. I don’t need the presenter to take the time to say things like, “At the end of my talk, I will conclude with some…conclusions.”

The other kind of outline slide, the one that the audience cannot understand, is the kind that tries to circumvent the lab-report headings by substituting in much more study-specific technical terms. This puts the speaker in a dilemma: if they just read the outline points, the audience won’t understand them. On the other hand, if they take the time to explain what each point means, they will end up repeating their presentation. Even if they do this well (and it’s my opinion that a well-done introduction should be solid enough to make such an additional “preview” unnecessary), there’s usually not much later on in the presentation to connect things back to the outline that ostensibly let the audience know the lay of the land. It’s like seeing the map for a road trip only once, before you get in the car, and then never again.

So: either the outline tells the audience that a presentation has the usual sections, or it tells them something that they’ll forget a slide or two later. In both cases, it’s a waste of time.

(Disclaimer: I have seen outline slides done well. In those cases the outline usually substitutes for the introduction. But they are so, so, so incredibly rare that I’m more than happy advocating the complete omission of outline slides.)

Slide Design and Layout

Here’s a typical slide I displayed.

I had four common elements on each slide:

• The Cornell seal and name of my lab, for branding.
• A brief list of the major sections of my presentation, with the current section highlighted. I find that this is very effective at letting the audience know where I am in my presentation and where I plan on going. It’s much more effective than, for example, a total slide count or a leading “outline” slide.
• A slide title. I go back and forth on whether this is necessary, given the moving highlighting in the section list above.
• A slide number.

The rest of the slide – and it’s quite a big area – is for content. And, in this case, I used that whole area for one thing. It’s certainly a spectacular picture, but I used this as a jumping-off point to talk about the Space Station and how it illustrates more than one application of spacecraft reconfiguration, the subject of my talk. It also illustrates the shortcomings of reconfiguration as implemented nowadays, since the Station’s robot arm is restricted to moving incredibly slowly.

You can see with this one how the black background helps with the space motif. It’s well worth the effort of color-inverting all my plots!

Often, I still end up needing to put a list on the screen. But a bullet list is not often the most desirable or effective way to do this. I have heard and read a number of designers who rail against bullet lists, and I agree with their reasoning: putting points in vertical order implies that each bullet is equivalent in some way, giving the points a parallelism that often doesn’t exist. (Check out the made-up example slide I led off with. Each bullet has a different kind of content. The bullet texts are not even the same type of phrase!) A list also implies some kind of order or hierarchy: the audience will read from top to bottom, making the first and last items in the list stand out.

Here’s the way I did it:

I put each list element in a little box, because they are separate concepts. The boxes also help me set off each item from the other items, making their mis-alignment very obvious. The message I was going for: this is a collection of concepts; they have something to do with each other by virtue of appearing on the same slide, but they are not arranged in list order and aren’t necessarily the same “level” of idea. I also went with a graphic, floating in space over the black background, that connects with several of those concepts. Below is another example, but this time I separated out the elements by color to imply some additional grouping.

Technical Content Slides

Of course, this presentation isn’t all for entertainment. (I estimate a good mix might be 1 part entertainment per 2-3 parts science and engineering for a technical conference. Contrast with a general-interest lecture, or what people like Neil deGrasse Tyson, Carl Sagan, Phil Plait, etc do.) But being engaging and understandable and conveying rigorous technical content are not mutually exclusive! Take this example:

I was explaining the Udwadia-Kalaba method for generating equations of constrained motion. One way to represent kinematic constraints, visually, is that a point representing a system has to move along a surface – which gave me a great way to use the slide as a visual aid to explain the concept. I think this would make for much faster understanding by the audience than spamming equations, too, because I get to say “the system has to move in a way consistent with the constraints” without having to explain all the terms in an equation. Still, it’s a complex slide with a lot of parts to explain, so I used the animation features in Powerpoint (simple fade-ins, nothing fancy, as a rule!) to bring them in a few at a time and explain them in sequence. Using the animations is also useful to me, in that it reminds me to explain everything on the slide and reminds me of the presentation order I decided. I knew I’d be presenting on my own laptop, so I didn’t have to worry about the animations porting over – in the past, I’ve used the trick of making each step in the animation a separate slide to make sure things go smoothly.

I do have the equation there, of course. And I took the time to point out all the important terms. But that doesn’t mean that this slide isn’t pretty! I saw many slides at the conference with similar content, but in Powerpoint bullet-list form.

Results Slides

Of course, the reason to give a presentation like this is to highlight some results. Often, this means graphs. Those results should be displayed as big and easy to read as possible. The black background helps for making things stand out, but there are certain necessities: big fonts and axis labels, in particular.

My favorite way to display results, though, is with movies. I mean, I’m talking about spacecraft made of modules that all slide and swing around each other to morph the whole spacecraft. I could make that extremely dry, but a good way to demonstrate that I’ve developed these algorithms and that they handle control of reconfigurable systems is to show it working. But it’s important to spend the time to put a polished movie together, to integrate it with the rest of the presentation, and to be familiar with its technical content so that I can use the movie to demonstrate my technical points. (Once again: visual aid.)

Believe me, engineers are suckers for cool movies. YouTube has a lot of hits for robotics research, for instance.

Miscellania

Contrast

Making the presentation easy to read is especially important, and it’s worthwhile to keep in mind that reading off a screen and from a projection are different. On your monitor, with light beaming out towards your face, it’s sometimes worth it to use low-contrast settings to keep things easy on the eyes. But on a projection in a dim – not dark – room, it’s better to make everything stand out.

I like to stick to a pretty small color palette, with the exception of photos and movies, which look more natural. For high contrast against black, I used a lot of white, light grays for accents, green, yellow, and cyan. (Blue and red – 0,0,1 and 1,0,0 – on black are bad ideas.  They can easily wash out in a dim room.) Color is a way to convey information, and if I don’t need that information, then I try to keep things black and white.

Fonts

As with colors and contrast, the key thing with fonts is to keep them easy to read. The presentation slides I’ve been pasting use a combination of Eras Medium for headings, Candara for the section highlight bar, and Segoe for text. All of those are sans-serif fonts with easily discernible characters. I could simply have used Arial or Calibri, but I chose to break from the defaults as just another way to say, “my presentation is different from all the others you’ve seen!”

Section Breaks

I have come to like placing minor-heading slides between the major sections of my presentation. Again, that’s a way to keep the audience in the loop about where the presentation is going. But I like them for an even more important reason, which is that they help remind me about the transitions!

Slide Counts

I’ve heard a number of heuristics for how many slides should be in a presentation. Ten total, or one per minute, and the like. It’s hard for me to come up with a reasonable heuristic for myself, though, because I tend to simplify my slides a lot, meaning that there are more of them but I go through them faster. I ended up with 33 slides, presented in 20-25 minutes, at GNC, but about five of those were heading slides and there were a few groups of 2-3 slides that expounded the same concept, so “one concept per minute” might work to describe my style.

Other Stuff

I always include an acknowledgment slide, because research is not usually done alone.

I also like to end my presentations with a repeat of my title slide (though I added in my group’s web site address), which lets the audience connect the graphic they first saw with the context of the rest of my presentation and reminds them who I am, where I’m from, and the title of my paper in case they want to look it up later.

In addition, I keep a bunch of backup slides on hand. Since my presentation style focuses on giving highlights, it’s entirely possible that I’ll get questions about the details; so, I make up a bunch of slides (or paste in from previous presentations) about my prior work or specific details, especially if I can anticipate what questions the audience will ask. If I use the backup slides, I get to look especially well-prepared!

Powerpoint contains this neat feature that lets you make slide templates (in Powerpoint 2007, look for “View Master” under the “View” ribbon). I get a lot of leverage out of the master template slides to get a consistent theme for my titles, headings, and content slides. Slide masters are also an easy way to get the section highlighting in the mini-outline in my header to work without lots of headachy monkeying around with tons of colors and styles on each slide individually. I typically base all my masters on the “blank” template, without any automatically-generated text box placeholders, so I can look at each slide as an empty canvas.

That’s All

Okay, I’ll get off my soapbox now. Maybe I will make some of my Powerpoint presentation templates available. My goals are both clarity in conveying content and engagement of the audience. I try not to sacrifice too much for one or the other, and have ended up at a distinctive, minimalist style. From the feedback I’ve received, it’s generally successful.

I have to give a bit of a shout-out here to the Williams College Physics department, which requires its research students to do a lot of presentations. Those prepared me very well for grad school. There’s also an incident that stands out in my mind in which physics profs Daniel Aalberts and Dwight Whitaker did a joint physics colloquium in which they (intentionally) demonstrated everything that a presenter could do wrong. If I ever am in a position to teach students about presentations, I’d love to play with that!

I hand-coded, from scratch, a multibody dynamics simulation package for Matlab.

This was for my research on treating reconfigurable spacecraft as kinematic mechanisms. We’re looking at how a modular spacecraft with joints (hinges, sliding surfaces, etc) between modules could twist itself around to rearrange itself. The idea is that changing the spacecraft’s shape could also change its functionality at a system level. Right now, proposals to do this involve having all the modules split off from one another, dodge around each other, and re-connect. Our thought is that the joints – the system’s kinematics, in engineering parlance – could dictate the motion in a desirable way. When modules come near one another, they can latch up and engage new joints, then twist around yet again. And again, and again, and again…until the whole system reaches the configuration we want.

In order to do numerical studies of the behavior of such a system, we needed a way to simulate multibody dynamics. We also needed the ability to explicitly control the kinematics of the system during simulation. And, since we don’t necessarily know conditions on the positions and orientations of all these modules (that’s what we’d like to discover!), we wanted tools based on a singularity-free representation such as quaternions. With few university licenses fitting that bill to play with, and surprisingly few relevant hits in the Matlab file exchange for multibody dynamics, I decided to write my own.

I call it QuIRK, which ostensibly stands for Quaternion-state Interface for Rigid-body Kinetics, but mostly I just like the name. (I was actually going for “clockwork,” but couldn’t get the “clo” to happen!)

This thing is pretty remarkably capable for a hand-coded multibody dynamics package. Once I had the toolbox functions, for instance, I produced this movie of a crazy lightly damped double-pendulum jouncing around with only twelve function calls. That’s twelve from Matlab startup to having the movie file as you see it.

[There is a video that cannot be displayed in this feed. Visit the blog entry to see the video.]

Pretty neat, huh?

I wrote up extensive online documentation for my functions and put the whole thing available for download here: www.spacecraftresearch.com/flux/quirk. And, if you’re the sort of person who goes to the AIAA Guidance, Navigation, and Control Conference, I will presenting our research application of this dynamics simulator package there!

Suppose you ask: Hey, Joe! What’s your research about?

Well, it’s about building Transformers in space out of Legos connected by tractor beams. Seriously. Okay, fine, they’re not “tractor beams,” more like…”tractor fields.” But other than that, not a bad description. Here’s an old-ish video version:

First: Why?!

There are a lot of possible reasons why we ought to be thinking about building large-scale structures in space. Imagine assembling a huge space telescope out of hundreds of mirror segments, giving the telescope an effective light-gathering area of hundreds of meters and letting us peer into the dimmest corners of the Universe – from the most distant objects to extrasolar planets. Or, if we’re interested in space-based solar power (putting solar power collectors in space, where they could gather sunlight 24 hours a day without atmospheric filtering, and then beaming that power down to Earth) we would want to make the biggest collector area we can. Proponents of geoengineering approaches to climate change mitigation have been seriously considering constructing a giant sunshade to reduce solar incidence on the Earth, a short-term solution that could stave off environmental impacts while we work up longer-term fixes. And finally, if we want to maintain a long-term human presence in space – from Mars explorers to microgravity research and manufacturing technicians to paying space tourists – we will need vehicles and stations with enough room to accommodate many people, hold life support and other supplies, and provide equipment to stave off the detrimental effects of microgravity on human physiology.

All of these possible applications – any one of which would have tremendous implications for our lives on Earth – demand that we build a large structure in orbit out of smaller components. The reason for this is simple: launch vehicles can only carry so much mass and volume into orbit. Those limits are on the “stowed” size of spacecraft, so we do have the option to build craft that deploy, or unfold, out of their tightly-packed, mostly cylindrical launch configuration and into some more spindly and useful shape. For example, most Earth-orbiting satellites get their power from large solar panel “wings” that would not fit into a launch vehicle fairing unless rolled up in some clever way. There’s a lot of research these days on inflatable spacecraft, that could expand to many times their stowed size and get structural support from their internal pressure, but even those balloon-like craft cannot get indefinitely bigger than their launch envelope. Deployments and inflatables only make the volume or length of the spacecraft larger – so, for the same mass, you end up with spindlier structures, which might be fine for some applications but not others. So, in order to get the really big spacecraft, we must assemble smaller pieces to make the final system. Think of the International Space Station assembly process. 

Legos

The concept of modularity is simple: build your spacecraft out of smaller pieces, each of which has only a small fraction of the functionality you want out of the entire system, such that the whole can do more than the sum of its parts. This might sound like it fits the description of anything build out of more than one component, but the key to modularity lies in the interfaces between components. Interfaces should be standardized such that you should be able to connect two modules together without really worrying about which function each module performs. So, if you want a space telescope, you build your spacecraft from a power module, propulsion module, telemetry and command module, communications module, and science instrument module. If you want a GPS satellite, you can take the same power, propulsion, T&C, and comm module, but instead of instruments have a GPS transmitter module. If you want to send the telescope to a Lagrange point, you just substitute a beefier propulsion module. Once the initial modular design is complete, development costs go way down – you just pick your parts. These modules are the “Legos” of the spacecraft. Each Lego brick has some basic function (its shape) and they have standardized interfaces (the studs). The selection of bricks, and the way in which you connect them together, determine the functionality of the final system – but you never have to worry about whether bricks of different shapes will connect, or have to mold all the bricks yourself.

A great example of a modular system is the USB architecture. If you go out and buy a USB device, it doesn’t really matter what that device is – keyboard, webcam, printer, or hard drive, you are pretty much guaranteed that there is some software that will let the device work with your computer as long as you have a USB interface and can run the software. Imagine having to buy a new computer built specifically for and around the new mouse! Such modular designs are very common in the computing industry, from IDE and ATA devices to object-oriented code to browser extensions. Even software itself: when I install a program, I don’t expect the process to involve reinstalling a new version of the operating system!

The spacecraft industry, however, has been slow to adopt modular design principles. There are some very good reasons for this! One reason involves the high expense of getting things into space and the harsh space environment (radiation is not kind to electronics). So, engineers typically want to be absolutely sure that their spacecraft will work once in orbit. They carefully design most systems around a small set of specific functions (space telescope, weather radar, GPS, …) and integrate everything together to work exactly right, subject to extensive testing. This makes sense: nobody wants to launch a multi-million-dollar satellite only to have it fail right after launch because some piece of code doesn’t play nice with some hardware component. After all, the engineers can’t just go online and download missing USB drivers like we can when our new printer doesn’t work immediately after we plug it in! A second important reason why most spacecraft are “monolithic” rather than modular designs has to do with how optimized spacecraft have to be. All these interfaces between components are little bits of mass and volume that take away from a spacecraft’s payload.

There’s an interesting (though not perfect!) parallel here with desktop Macs and PCs. External devices and third-party software aside, Macs tend to be monolithic, while PCs tend to be modular. PC users can swap out different graphics cards, DVD drives, hard disks, RAM, CPUs, Ethernet cards, et cetera. That makes PCs, typically, cheaper than Macs for comparable functionality, upgradeable and expandable when any new functionality comes out, and gives end users the ability to replace old or broken components – even build their own computers – without specialized training or equipment. However, that also tends to make desktop PCs larger in form factor than Macs and potentially less reliable, as PC software must allow for many more possible combinations of hardware. Right now, spacecraft tend to be like Macs because the spacecraft industry is risk-averse and already must deal with high costs. I want them to be like PCs to bring costs down, allow upgrades, and introduce the potential for more functionality.

International Space Station (NASA)

Modular spacecraft do exist. Great examples are the Hubble Space Telescope and International Space Station. The Hubble was built with modular instrument bays inside its structure; this allowed astronauts on the five HST Servicing Missions to open up the bay doors, pull out the old modules, and slot in new ones without having to disassemble the whole telescope on a spacewalk. That design decision has kept Hubble operating and returning stellar (ha!) imagery for almost twenty years. The Space Station was designed and built with the idea that the components could be brought into orbit and assembled using the Space Shuttle as a work platform, and so we end up with Shuttle-cargo-bay sized modules that astronauts, working with the STS and ISS Canadarms, pieced together. Each module has some set of functions (laboratories, living quarters, nodes, airlocks, truss segments, solar panels, logistics, …) and some of them have even been disconnected from temporary berths and moved to different locations during the ISS assembly process.

What would make modularity easier to achieve on spacecraft is a better way to build the interfaces between components. Something that doesn’t require a lot of mass and volume on the ends of the modules, and doesn’t require a lot of finesse from astronauts or robot arms to assemble. We get this by, essentially, abstracting the interface away: transfer data and power wirelessly between modules, and you don’t have to have any connectors. More radically than that, though, we want to have an interface that works by some principle that ties the dynamics of neighboring modules together (a general statement of what a mating adapter or truss does) but without physical contact.

Concept of a non-contacting space station

This is kind of like spacecraft formation flight – in which a swarm of small vehicles form a sort of “virtual structure,” perhaps with a time-varying shape, that lets them perform some function as a group. For example, a space-based interferometry mission like the proposed Terrestrial Planet Finder consists of a cluster of spacecraft that must hold a particular shape and cooperate their motions and actions. All of this usually gets accomplished by extensive feedback control. However, our idea is that we can come up with technological solutions to those challenges, rather than control-based solutions, by using force-field interactions to establish passive dynamic relationships between spacecraft modules.

The Electromagnetic Formation Flight (EMFF) and Coulomb Formation Flight (CFF) projects at MIT and UC Boulder, respectively, are similar to our approach in that they use attractive and repulsive forces between spacecraft to keep them in some desired configuration. However, they must use control to stabilize the interaction, or else the formation will either collapse and collide or fly apart. Our choice of physics is magnetic flux pinning, which gives spacecraft passively stable dynamics when they get very close to one another.

Tractor Beams

Magnetic flux pinning is an interaction between a magnetic field and a type II high-temperature superconductor. “High temperature” is very relative here: these materials have zero electrical resistance below a critical temperature that is often around 80-100 Kelvin, liquid nitrogen temperatures, instead of 1-5 K, liquid helium temperatures. The favorite in our lab is yttrium barium copper oxide (YBCO), one of the first HTSC’s discovered.

Magnetic field penetrating a superconductor

When the YBCO is above critical temperature, it’s just a piece of ceramic. We can place a permanent magnet near it and the magnetic field will happily penetrate the YBCO. But when the YBCO cools, interesting things start to happen. The magnetic field starts to induce currents – and those currents have magnetic fields of their own. Since there is zero electrical resistance in the superconductor, the fields from all those little supercurrents exactly oppose the field of the magnet. But YBCO is a special type of superconductor, laced with impurities – little regions of nonzero resistance. That leads to a far more subtle interaction than the YBCO simply repelling all applied magnetic fields.

What happens is that the YBCO sort of tries to maintain the magnetic flux distribution that was present within its volume when it cooled. The net effect is that the YBCO exerts a restoring force on the magnet, pushing it back to the same position and orientation it had when the YBCO temperature crossed below critical. The interaction provides nonlinear stiffness and damping, effects which get stronger as the magnet and YBCO get closer together, and the equilibrium position of the magnet and superconductor depends on their initial positions. All this comes without any power or control: all you need to do is keep the superconductor cool. Away from Earth’s reflected light, that could be done with a sunshade – and beyond about the orbit of Mars, the superconductors would be below critical temperature without any shielding at all. The magnet and YBCO stick together passively, with a several-centimeter gap between them.

A flux-pinned magnet floating above YBCO

For my first couple years of graduate study, I spent my time characterizing this flux pinning interaction for spacecraft applications. We needed to know how stiff the interaction is in all six rigid-body degrees of freedom (three translations and three rotations), simultaneously. First, we did quasistatic stiffness measurements of a magnet pinned to 19 tiled hexagonal pieces of YBCO. We used a (supposedly precision) robot arm to make small displacements and rotations of the magnet, and a 6-degree-of-freedom load cell to measure all the restoring forces and torques simultaneously. From that data, we estimated the 6D stiffness matrix of the pinned magnet and YBCO. Later, we did dynamic measurements: we hung a magnet from a long pendulum and pinned it to an upright, much higher-quality YBCO disk next to the pendulum’s equilibrium position, excited vibrations of the pendulum by feeding white noise to an electromagnet coil, and tracked the response of the flux-pinned pendulum by motion capture. That experiment gave us both stiffness and damping information, and we used the pendulum experiments to explore how shaping the flux-pinned magnetic field affected the macroscopic properties of the magnet-YBCO interaction.

I was able to determine that a permanent magnet flux-pinned to a YBCO disk can have stiffnesses up to hundreds of Newtons per meter when they are separated by a centimeter or so at the time of field-cooling. The stiffness drops off exponentially as the field-cooling separation increases, out to a maximum range of 7-9 cm for the magnet and superconductor I tested. That’s not exactly the stiffness of a steel girder, or even of a truss segment on ISS, but it is high enough to withstand the typical perturbation forces in the space environment: gravity gradient, solar pressure, atmospheric drag, and others. So flux pinning could be enough to hold multiple spacecraft together into a single structure, passively, once they come within close range. We can also change the stiffness and damping of the interface, by design, if we place metals that interact with magnetic fields near the YBCO.

Pouring nitrogen into an early motion capture pendulum setup

Last summer, I participated in a NASA microgravity flight that grew out of this research. Our team devoted one of our two flight days to an attempt at testing the 6DOF stiffness of a CubeSat-sized spacecraft mockup flux-pinned to a superconductor in a nitrogen-filled 3U-CubeSat-sized Dewar. That was our first microgravity flight, and the lack of experience really impacted our ability to get good data. Which is to say, we didn’t. Get good data, that is. We did see low-stiffness pinning of the CubeSat to the Dewar, but weren’t able to get a measure of that stiffness. Now that we have that experience under our belts, though, we should have a much better-designed experiment this coming summer!

Transformers

How many times has this happened to you: you build a multimilliondollar spacecraft, drop a few tens of millions of bucks on a launch, get it into orbit, and suddenly you smack your forehead and cry, “Man, I wish this spacecraft could do X?” Or maybe your spacecraft just up and broke, and you’d like to fix it. Or maybe it’s done with its mission, but it still has propellant and functional systems, and you’d like to do some more stuff with it, but the payload isn’t any good for what you’d like now. In all three cases, it’s time to build a new spacecraft!

Spacecraft are typically one-shot vehicles, built for a very specific function. But if we consider modular spacecraft, as above, we can start to consider changing functionality by adding, removing, and swapping out components – or even just by altering their physical layout. A couple examples of current vehicles that change functionality by changing shape might be the F-14 Tomcat - a “swing-wing” aircraft, which uses different wing shapes to optimize its performance at super- and sub-sonic speeds – or the V-22 Osprey, which changes shape to go between “helicopter-like” flight and “airplane-like” flight. A more dramatic example is the Terrafugia vehicle that transforms between a road-drivable “car mode” and FAA-compliant “airplane mode.”

In the space world, there are also a few great cases in which the craft experienced some change in functionality as a result of changing components or component layouts. One is the Hubble Space Telescope, which has had several servicing missions, each of which added or changed parts of the spacecraft. Another is the International Space Station. Take a careful look at this animation of the assembly process, and you will notice not only steps in which components get added to the station, but steps in which a component disappears from one part of the station and reappears in another. What’s going on in both cases is a process of reconfiguration – a generalized word that encompasses adding things, removing things, and rearranging things.

Both of these examples involve lengthy and complicated maneuvers with dexterous robotics and human spacewalks. When engineers think about reconfiguration, if they think about reconfiguration, they typically think about the control process necessary to accomplish such gymnastics. Even the most reconfigurable space systems envisioned, such as the SPHERES project at MIT, view reconfiguration as a process of simultaneously undocking the modular components from their current configuration, maneuvering them to their target positions and orientations, avoiding collisions with all the other maneuvering vehicles, and then docking again in their new configuration. That’s a tremendous control problem, and the usual solutions generally involve many vehicles sensing their state very accurately and communicating it near-perfectly to each other. If the communication gets garbled, a sensor develops a bias, or an actuator goes wonky, the risk of modules colliding and ruining the whole system skyrockets.

For the last year, I’ve been working on an approach to reconfiguration that involves picking the system kinematics so that the physics of the problem naturally drive and regulate the reconfiguration maneuvers in a very power-efficient and reliable way. “Kinematics” are the set of paths in space along which a set of bodies can move – usually defined by system joints. For instance, a typical door can swing open and closed, but cannot move sideways – likewise, a sliding door can translate in and out along one line, but cannot rotate. The question I’m asking boils down to this: Can we take a modular space system and get it to reconfigure by changing the way the modules are allowed to move with respect to one another?

An asymmetric magnet has stiffness in all degrees of freedom

What inspired us to look at this question was the sight, common in our lab, of a cylindrically symmetric magnet flux-pinned to a superconductor. The magnet’s axis of symmetry allows it to act as a revolute joint – a hinge – with one rotation degree of freedom about its axis and stiffness in all other degrees of freedom. But in addition, if that symmetry gets spoiled – perhaps by an electromagnet or another permanent magnet – then the free rotation gets locked out with some stiffness. So, with flux pinning, we actually have a way to change joint kinematics on the fly, simply by changing magnetic fields.

Now, if we have a modular space system held together by flux-pinned connections, we can specify whether each interface is completely fixed, or has some degrees of freedom. We can reconfigure the vehicle by releasing some of those degrees of freedom. If the spacecraft is in orbit around a planet, or near the radiation of a star, or in a magnetic field, or spinning, then there will be some set of forces and torques on the individual modules making up the craft which will push the craft – bending it along the kinematic pathways we specified. Eventually, the modules will naturally tumble down into an equilibrium. Then we can pick a new set of kinematics and allow the spacecraft to tumble again. And again, and again, and again…. Once it gets to the configuration we want, we have the spacecraft lock out its kinematics. So, we could have spacecraft modules “walk” around to new locations without ever disconnecting them from the rest of the spacecraft, or even have the entire system move like a mechanism with gears, chains, and linkages.

Some interesting features of this method of reconfiguration are that it doesn’t require any power input (except when the kinematics change) and the spacecraft doesn’t need active control when it is moving between these intermediate stepping-stone configurations. We let the natural physics of the system determine how the spacecraft moves. That lets us enforce collision prevention – and other undesirable behaviors – simply by choosing kinematics that we know will lead to safe motions. Computers on board the spacecraft need only keep track of the possible equilibrium configurations and the sets of kinematics that lead between them; then, when the spacecraft gets a command to reconfigure, it does a graph search to figure out which intermediate steps to go through. Each configuration is a “safe step” – since we let ambient forces in the space environment drive the process, each set of dynamics is passively stable. If something breaks, it just gets stuck at the equilibrium configuration where it is and ground controllers can troubleshoot the problem from a stable point.

The Future

Prototype of a CubeSat-sized vehicle that floats on air feet

Right now, I’m working on some of the math behind this reconfiguration stuff; I’m trying to develop algorithms that a spacecraft could implement. In the near future, my lab will be trying out these algorithms on an air-levitated testbed of nanosatellite-scale vehicles. We’re also working up to more involved microgravity experiments that will include several vehicles with flux-pinned interfaces maneuvering around one another. We recently ordered a cryocooler to keep our superconductors superconducting, and my labmates have started machining parts and designing electronics. Further afield, we may try to get an actual CubeSat designed and built to demonstrate flux pinning on spacecraft.

Flux-pinned CubeSat concept

In general, all this flux pinning stuff could evolve into a technology that helps make in-orbit modular spacecraft assembly much easier, and gives engineers more options to reconfigure existing systems. Imagine spacecraft that you could add new capabilities to whenever a small-satellite launch comes up, spacecraft with “recyclable” parts that can be repurposed into entirely different systems at the end of their designed life, or spacecraft that can split into several different sub-missions.

For instance, imagine sending a probe to Jupiter, having it leave some of its instruments in orbit around Europa, pointing half of the spacecraft at Jupiter and half at Ganymede as it swings around, picking up the Europa instruments on another flyby, and eventually receiving some extra fuel tanks, replacement computer parts, and upgrade instruments from Earth. Or, imagine building a spacecraft out of power modules, fuel tanks, crew habitats, centrifuge modules, and lab modules in Earth orbit…sending up a propulsion modules to blast the whole thing to Mars…and having astronauts go down to the surface in lander modules, leaving the habitats in orbit. Imagine supplying the orbiting habitat with more fuel, propulsion, and habitat modules on subsequent launches. Imagine building up an orbital station and return vehicles at the same time as we build up a ground station. And if there’s any problem, we can reconfigure the spacecraft to repair it.

A cartoony reconfiguration concept

I like to think that technologies like this will help us expand our exploration out into the Solar System. And in the meantime, I’ll get a Ph.D. out of it!

I, personally, rebel against using TeX or its derivatives in my academic work. Yes, I can program in Matlab and Mathematica, and yes, I can create some pretty snazzy HTML/CSS web pages, so I’m not foreign to coding and markup languages, but really, I’m trying to concentrate on the science and engineering when I write a paper. I want to see what I will get. There is no reason at this point in the history of computers for me to have to use a command-line word processor that I have to compile. That sort of thing is for numerical scripts, not for documents.

Word 2007 took some great strides in the direction of making Office easier and better for technical purposes, with a WYSIWYG equation editor that you can control almost entirely from the keyboard using common operators and that automatically prettifies the equations as you write them. It’s way cool.

Word 2007 also has, from the beginning, included some automatic citation generating and outputting features. It’s almost like EndNote or BibTex and such, except that I don’t have to pay extra for them. However, it’s HUGE shortcoming was that it contained only 10 citation formats, and didn’t include some common technical formats. Right around the release of Office 2007, Microsoft blogs touting Word went on and on about how easy it would be for users to generate their own formats, since they used open XML files to create them. However, it turns out that those XML files are totally opaque to my understanding, and when I did try to change some things, I didn’t get what I expected. And it seemed like the rest of everybody agreed with me, because downloads for new citation formats did not immediately appear on the Internet.

I have finally, finally, finally found a web site with a small library of citation format files. It is here.

They unfortunately don’t have the AIAA format, which is what I use most often, but maybe they have something close. And, anyway, it adds to my options for the future.

An article just appeared in the Cornell Chronicle about our stuff.

We’ll be applying to fly a refined experiment on the Vomit Comet next summer, as well, through the NASA FAST program. (Check out the link to our video on the FAST front page!)

My research group at Cornell got an opportunity to fly an experiment on a microgravity flight sponsored by NASA. We’ve been doing research on how an effect called magnetic flux pinning, in which a magnet sticks to a superconductor without touching it, could be used to assemble, hold together, and reconfigure spacecraft. While I was interning at Johnson Space Center this summer, my team designed and built a shoebox-sized dewar for holding cryocooled YBCO superconductors and two mockup CubeSats – 10x10x10 cm spacecraft – containing magnets and electromagnets. We took them to Houston to try out flux pinning on the Zero-G Corporation’s aircraft – “G-Force One” – a modified Boeing 727 that is now of the sort of aircraft known affectionately as the “Vomit Comet.”

Before I was cleared to fly, I had to jump through some medical qualification hoops. I have type I diabetes, and have in the past been diagnosed with asthma. Several letters from my doctors and one pulmonary function test later, I had the okay for physiological training and then flight. “Physiological training” consists of classroom lectures about what happens to a human body during ascent to altitude, oxygen deprivation (hypoxia), and spatial disorientation, followed by a session in a pressure chamber designed to simulate a flight to 25,000 feet.

View of the Neutral Bouyancy Lab's 40-foot-deep tank and the altitude chamber below it

Physiological training was at the Sonny Carter Training Facility, home of the Neutral Bouyancy Lab (NBL) where astronauts train for spacewalks. That photo above shows off the 40-foot-deep pool, which looms over the altitude chamber – that chunky rectangular room directly below the “Welcome to the NBL” banner. In the chamber run, they bring in 16 participants and seat them in two rows of 8, facing each other, put them on 100% oxygen through a mask system (all wear fighter-pilot-style masks and snoopy communications caps), and then pump air out of the chamber until it gets to the same pressure as an altitude of 25,000 feet. Then, they have half of the participants take off their masks for five minutes to learn how they react to hypoxia (while under very strict supervision). You see, everyone’s hypoxia symptoms are different: loss of concentration, peripheral or color vision, shaking, euphoria, lethargy, blue lips and fingernails, or dizziness. The purpose of the altitude chamber run is for us to recognize what our hypoxia symptoms are, so that if we’re in an airplane that decompresses, we’ll recognize when we need to go get emergency supplemental oxygen equipment. (In other words, we were learning exactly why they tell you, “Put your own mask on first, then assist others.”)

When it came time for me to take part in the demonstration, I dropped my mask and stared ahead at Max, my Cornell teammate. He had dropped his mask for five minutes earlier, while I observed. They handed us a worksheet to fill out while we were off the masks, consisting of some simple brain exercises. At first, nothing seemed terribly different from breathing normally. I looked around the chamber, at the other participants, my teammate, the worksheet, and some color wheels placed around the interior of the chamber. I held my fingers up to either side of my head to check my peripheral vision, and glanced at my fingernails to see if they were turning blue, and started in on the brain teasers. Almost immediately, my hands started to shake visibly. I scrambled to answer the worksheet questions, nervous about what might happen while I was writing. My chief worry was that loss of concentration would be one of my hypoxia symptoms. I kept checking peripheral and color vision, and didn’t notice any change. After a few minutes, I felt like the muscles just under the skin in my torso and ankles started to shake along with my hands. But then, after about four minutes at 25,000 feet, I found out that I’m one of the lucky ones for whom euphoria is a hypoxia symptom – the shaking stopped, and I felt much better. That’s a false feeling, though – as I was actually becoming quite dizzy without my brain realizing it. Max can attest that after five minutes, as soon as I put the mask back on, I suddenly registered my dizziness – and I reeled for a moment before the 100% oxygen flow got back into my system. About fifteen minutes later, the chamber was back to 1 atm pressure and we were filing out.

Our flight week involved a lot of work in intense heat and humidity in a hangar at Ellington field, as well as late nights at my sublet while we finished up NASA documentation and got our equipment up to the loading standards for the Zero-G aircraft. A lot of pizza, hardware store runs, typing, metal-sawing, The Beastmaster, and one 4 AM run to Kinko’s later, and we were ready for our Test Readiness Review by NASA officials.

The team after a *very* successful TRR: Max (holding the superconductor dewar), Laura (with one of the CubeSat mockups), me (and a high-speed camera), and William (holding the other mockup CubeSat)

We passed with flying colors and got ready to load the plane! (One of the NASA reps told me afterwards that our TRR was one of the best of the day.) The 727 has a rear stairway under the tail engine, standard airliner seating in the rear of the cabin, and the middle and forward part of the cabin is just open, padded space. We carried in our mounting boxes, laid them out, and had them bolted to the airframe. Eight other experiments flew both days we were up, each with at least three flight crew, plus there were about five or six NASA crew each day, so it got kind of crowded. Then we left Ellington Field and went out for a steak dinner – since Max and I heard at physiological training that a high-protein diet helps stave off motion sickness.

The modified Boeing 727, ready for staging and loading of experiments

Flight day 1 began with some frantic setup in the hangar as Max got the dewar filled with nitrogen to keep our superconductors cold. Laura, William, and I were the flight team for the day, so we headed off to get our preflight briefing and medical briefings. At the med briefing, they gave us all some scop-dex, a two-medication cocktail tailored to shut our inner ears down and help prevent motion sickness. The preflight brief let us all know about the flight plan for the day: since none of the experimenters specifically requested a break, we were going to go up over the Gulf of Mexico and knock out as many parabolic trajectories as possible before the plane would turn around and parabola its way back towards Ellington.

Laura, William, and I came back to the hangar to grab the dewar, which Max kept topped off and had ready to go just before flight. We boarded the plane through the rear stairway, secured the experiment in its case, and then came back to the seating in the rear of the cabin. We got a brief safety overview (cards in our seat-back pockets and everything). Takeoff and climbing to cruise altitude was more uneventful than on a standard airliner, given that there weren’t any windows to be seen from our seats. Then, we got a signal that we were free to move about the cabin. We unstrapped, climbed out into the aisle, and made our way forward into the padded central cabin where our experiment cases were bolted to the airframe.

Getting the laptop set up to control the experiment and getting situated with a legstrap.

We got our cases undogged, our feet under some legstraps, and got ready to pull out the CubeSat mockups. The aircrew waited until all nine teams of experimenters said they were ready to go, and then the plane unceremoniously went into a high-g climb. I saw the flight surgeon lie down behind me a moment before, so I emulated him and lay on my back next to the laptop. There’s a monitor at either end of the cabin that shows the current parabola number and the effective gee force, but lying down, I couldn’t see it. I could definitely feel it as the plane poured on the g’s up to about 1.8g. (I don’t understand fighter pilots who get up to 6g. Or 8g. Or 10g. 2g was uncomfortable enough for me.) The extra “gravity” pressed me tightly into the floor padding.

In two gravitites, getting my camera ready for zero-g.

Then the plane nosed over. As it comes into the top of its parabolic trajectory, the downward acceleration of the plane exactly matches gravity and everything inside the cabin is in freefall for about 26 seconds. Almost immediately, I felt like I was falling and flailed my arms around a bit to grab onto something – which, of course, does nothing except for maybe letting me hit something. I had the legstrap over my lower right thigh, thinking that would hold me. It didn’t: the single point of contact acted as a pivot rather than securing me, so the first thing that happened to me was that I floated around and twisted involuntarily towards the side of the plane, shouting “Waaaauuugh!”

Coming up off the floor as we go into microgravity

One of the first things that I learned about microgravity is how hard it is to control yourself in a short timescale. Unless you’re methodical in your movements from the start (I got used to counting from about three to five from when I first felt like I was in “zero gee” before I started actually moving around) you kind of bounce around. Again, to us physicists and engineers, this shouldn’t be a surprise, but it takes intuition a while to catch up!

Free-floating!

Microgravity almost doesn’t feel exciting at all, once the falling sensation fades. I mean, it doesn’t feel like anything. I just hung there in space. My inner ears told me nothing (partially thanks to the scop-dex). My sense of touch didn’t tell me that I was touching anything, because if I did, the normal force would push me away pretty quickly. I wasn’t sitting or standing on anything. The best way I can describe it is to say, “you’re just there.”

As an example of what I mean, take this little maneuver:

That looks like tremendous fun, but I have to say, it was kinda boring. The only thing I had to go on to know that I was spinning at all was my eyes. Even my partially functional inner ears were silent – after all, once I lost contact with the floor, I was rotating at constant velocity! (Now, of course, being a physicsy guy, I know how to make that fun. Given a bit longer than 25 seconds, or maybe just some careful planning, I’d love to try out some other experiments with linear and angular momentum, or exploit the human body’s nonholonomic constraints. And, really, I’m not going to contend that I didn’t love every second of that.)

We worked diligently at our experiment for about 20 parabolae, after 3 just getting used to handlign ourselves and our equipment in zero g. William and Laura had the tasks of pulling our experimental dewar and CubeSat mockup out of a padded case at the beginning of each parabola, shepherding them together and watching the magnets and superconductors flux pin together, and then stuffing them back into the case when the NASA crew gave us the “feet down!” warning. My job was to set up and record high-speed video of each parabola, call out general directions to Laura and William for the best video, and control the CubeSat mockup via computer. Here’s a video I compiled of our research highlights:

For the last fifteen or so parabolae, our nitrogen had run out and the experiment no longer functioned. We tried a couple times to just pose the equipment to take some pretty pictures. After a bit of that, we just started to play around in zero gravity! At one point, to try and take photos from a different angle, I floated myself over to Laura and William’s side of our little experimental area, propelling myself along with a few pats of my hands against the floor and the cases bolted to the airframe. Now that is fun, just moving yourself along effortlessly! Look for a clip of that at the end of this next video.

All good things must come to an end, and after 20-25 seconds of microgravity, the NASA crew shouts for all the experimenters to get their feet under them once again and the effective gravity in the plane waxes up to 2 g’s in about a five-second transition period. I found that at 2 g’s, movement in general was difficult. I felt like I had to push my arms through soup. And, a couple times, I made the mistake of moving my head too quickly in 2 g. Then I can tell you my inner ears felt it. In fact, I will admit that of our flight crew, I was the sickest of the bunch – but only for the last two or three of 35 parabolae, and I did not vomit! By “sick,” I just mean that in the last 2 g parabola, I had to sit still with my head facing along the aircraft axis to line up with its motion. But I was fine. Here’s me towards the end of our run:

And then we went back to our seats, the aircraft landed, we unbuckled, and high-fived as we disembarked!

High-fives all around as we walk back across the tarmac!

The Day 1 flight team immediately postflight

That was the end of flight day 1, and my flight crew involvement. Max, the fourth member of our team, was on ground crew the first day and, since he’d done a lot of machining and gruntwork for us over the course of the summer (he wins my “destroying his body for the team” award for, erm, “machining” some steel) I volunteered that he could go up on day 2 instead of me. I just hung around on the ground and poured liquid nitrogen:

Dispensing LN2 from the big dewar, in protective gear in the 100+ F hangar.

The great news is that our team was successful enough that we’re going to be working towards another microgravity demo in summer 2010! This will probably be the capstone of my research. It’s certainly a great life achievement!

Apparently, it has been only two years since the Reduced Gravity Office at JSC has allowed anyone with diabetes onto the plane at all. I got all the clearances I needed and have been thrilled to be a part of such an experience. This might be the closest thing I get to going into space – but given what I’ve taken part in this summer (and will again next summer, if all goes according to plan), I don’t think I’ll rule that out. In a way, things have come full circle: the space program of the ’60s gave us the high-tolerance manufacturing capability and jump-started the microprocessor industry in such a way as to make, decades down the line, insulin pumps. My Animas pump, in turn, has given me the control over my diabetes I needed to pass NASA physical evaluations and get a flight spot on the Zero-G aircraft.

First, while I do some of the more mechanical computer modeling work during the day, I’ve been listening to a lot of NPR streamed over the Tubes. Today, I learned some factoids that basically break down as follows:

1. If you figure out how many people in America get health care and the quality of care they recieve, you find that we actually have the most “rationed” healthcare system of industrialized nations. That is, in a country with omg-we-can’t-have-that single-payer healthcare, or even anything not as vile and disgusting as that, more people get the care they need when they need it than in the USA.
2. If you figure out how much health care costs in this country, and compare it to the cost of health care in other countries – not just premiums, mind you, but tax money that goes into health care as well – you find that Americans have the most expensive health care system in the world.

If you’re thinking what I’m thinking, it’s that the GOP is neither morally nor fiscally responsible; and that they are not really “conservative” in any actual definition of the word. If you’re not thinking that, you’re probably a Republican and have just pegged me as a pinko commie godless bleeding-heart Massachusetts liberal. (I will give you three of the words in that phrase, contend that there’s nothing wrong with at least those three, and the rest I contest.) In fact, I am merely a scientist and engineer, and I know how to read numbers and am willing to make policy decisions based on data. I’m also insulin-dependent diabetic, and would seriously appreciate a much lower cost and more assurance of the efficacy of the treatments just keeping myself alive.

Second, I have been hoping to come up with some good theoretical results to present in a conference paper on my research later this summer, and it just hasn’t happened. I’ve been too busy with other work-related things, and now I’m in a summer internship at NASA and don’t have the time to spare, so results are not going to be forthcoming before the paper deadline. This leads me to conclude that I much prefer being an experimentalist to being a theoretician. The reason is that labs sometimes go the experimenter’s way, and sometimes they don’t – but part of that is uncontrollable. The experimenter can, though, usually sift through data to find some useful results. Even negative results are useful. Any results at all will at least shed light on the techniques employed. If theoretical work doesn’t go the theoretician’s way, however…you are just left with a theoretician staring blankly at a piece of paper with a lot of scratchwork. And a lack of results just means that the theoretician hasn’t done the right thing or worked hard enough yet.

In other words, I have no results and it’s my own damn fault. I can’t even blame fault apparatus, numerical noise, or experimental error. I just didn’t do enough, or the right kind of, work. And that just makes me less motivated to continue this line of inquiry.