What I Learned Today

The 1976 Viking landers conducted a handful of experiments that involved injecting a nutrient-laden solution into Martian soil, then measuring gases given off in response. Indeed, gases were observed from the regular soil, but not from soil that was first heated to 160 C (sterilized). That seemed intriguing to many scientists—but others noted that the same result could be obtained through (abiotic) chemical oxidation triggered by the application of water. If I understand the arguments, heating the soil would break down the presumed oxidizer in the soil so it would then react less or not at all to a new injection of moisture.

But lo and behold, the scientists who (still) insist that Viking found life have published a new paper: “Complexity Analysis of the Viking Labeled Release Experiments” by Bianciardi, Miller, Straat, and Levin. They’ve used “complexity variables” to characterize the time series data, then clustered them (with k-means clustering, k=2). Indeed, they found that presumed “active” samples (including some examples from Earth) clustered together while presumed “inactive” samples (including some controls from Earth) clustered in a different group.

Since my dissertation was on clustering, I thought I should take a look and see how this machine learning method was being used in this setting. And, well, I’m just not convinced. Yes, they do seem to have gotten two distinct populations. But they only used 15 samples (11 from Mars, 4 from Earth) and that hardly seems sufficient to characterize the range of behavior, nor are they all obviously comparable (one time series consists of “core temperature readings taken every minute from a rat in constant darkness”; how is this related to possible bacterial activity in soil? Is darkness relevant? What about a rat in daylight, or a diurnal cycle?). The authors have agreed that more data would be better. I think more data, and thoughtfully chosen, would be essential.

My other reservation is about the “complexity variables” that were used. These are presented with no justification or discussion:

• LZ complexity
• Hurst exponent
• Largest Lyapunov exponent
• Correlation dimension
• Entropy
• BDS statistic
• Correlation time

Especially since these generated the 7D space in which the clustering happened, it’d be nice to have some intuition about why these might relate to life. There are some brief comments about life being “ordered” and of “high complexity” (and I’ve worked on this subject myself!) but I’m not convinced that the distinction they found is truly meaningful.

I don’t want to be unscientifically biased or negative. The results as presented in the paper do seem to show a quantitative separation between active and inactive samples. But this should be conducted with hundreds or thousands of samples from the Earth at the very least, where we have tons of examples of life-bearing soils as well as artificial or sterilized samples. These could fill out the feature space and properly position the Viking observations in more context.

Of course, it would also be useful to get more Martian samples!

Most of what we know about Mars only goes skin deep. We’ve had several orbiters studying the planet with a variety of remote sensing instruments (cameras, lasers, radar, etc.) and several rovers running around on the surface. The Phoenix lander dug around in the soil a little.

But so far, we haven’t been able to look beneath that skin. No drills, no cores, no subsurface probes. We haven’t even gotten a seismometer to the planet, which could be used to learn about the composition of the planet’s interior, and help answer the question of whether Mars still has a molten core. (The Apollo astronauts put seismometers on the Moon to help answer similar questions.)

The InSight mission to Mars seeks to change that. InSight is a lander that will use a seismometer and a heat flow probe to learn about the planet’s interior. (It will also have a surface camera, of course!) The plan is for InSight to launch in early 2016 and land on Mars later that year.

We’ve studied Mars from the outside for decades now… it’s time to look under the hood!

InSight is competing with two other concepts to be the next Discovery mission to Mars. (The others are the Titan Mare Explorer and Comet Hopper.) One of the three will be selected in late 2012. Stay tuned!

The new NASA budget isn’t looking good, and Planetary Science in particular is taking a ***20%*** cut, most of which cuts Mars funding!

In a move that’s equal parts desperation and brilliance, the community is rallying to put on a nationwide Planetary Exploration Car Wash & Bake Sale on June 9. Each local organizer will send a check with the proceeds to Congress, requesting them to apply it to increase the planetary science budget.

If your car doesn’t need washing or you’re watching your waistline, check out this AAS site for information on how to contact congressfolk and a list of useful “talking points.” If you care about the future of planetary exploration, make your voice heard!

It had to come sooner or later: I hit my first plateau with the violin. You know, that point where you keep practicing and working and somehow nothing seems to improve (and sometimes things even get worse!). This is frustrating, but I recognize that it’s part of the process and you just have to push on. After a while, something will click, and you’ll start making progress again.

My plateau hit while working on the first two Minuets in Suzuki book #1. These are two simple pieces in 3/4 time in the key of G. I’ve gotten rather good at scales and arpeggios in the key of G (when I relax and focus), but this only means I hear my mistakes all the more when playing the pieces. :) You know you’re at a plateau when you start getting exactly the same feedback and homework assignments from your teacher on subsequent weeks.

For me, the struggle was in (as dumb as this sounds) using the whole bow. I’d gotten used to practicing with a small mid-section of the bow, as this made “enough” sound for me.

“No, no,” my teacher says. “This piece is to be played forte, and that means the whole bow!”

So, just use the whole bow, right? But you have to cram the whole bow into a quarter note. Suddenly I was rushing, trying to use up the whole bow’s real estate in one click of the metronome. And my intonation degraded, and the bow would make breathy sounds or skip on the strings. Ugh! Gradually I figured out that some of this can be addressed by pressing more firmly (“dig in!” says my teacher) and that it’s really an issue of good bow control (not just letting it slide across the strings), which will come with practice and time.

At about this point, I happened across the excellent “Teaching Suzuki” blog (by a Suzuki teacher) who coincidentally posted about Long Bow Day. She writes about the utility of setting aside a practice session just to work on long bows, and breaks this down very nicely. I went on to read some more of her posts, which manage somehow to be both delightful detailed and accessible, and fascinating in that they provide pedagogical insights about (her philosophy of) how one learns the violin. She appears to be working her way through book 1 right now, in her posts, so I’m eager for her to “catch up” to where I am with the evil Minuets. I love the chance to learn from someone else in addition to my weekly lessons.

Anyway, after much effort, I am making more forte-like sounds, and the intonation is improving. I feel I’m starting to break free of that static-feeling plateau. I’m also getting a bit better at some associated skills from these pieces, like triples (3 notes played in one quarter-note’s time; tricky mainly because it’s a rhythm change), staccato slurs, and “hopping” a left-hand finger to enable playing two notes in succession that require the same finger but are on different strings. Onward and upward!

It never occurred to me to wonder where Motorola got its name. Recently, I heard this fascinating tidbit and followed up — it appears to be true!

From Motorola’s own timeline:

In 1930 Galvin Manufacturing Corporation introduced the Motorola radio, one of the first commercially successful car radios. Company founder Paul V. Galvin created the brand name Motorola for the car radio — linking “motor” (for motorcar) with “ola” (which implied sound). Thus the Motorola brand meant sound in motion.

Today, Motorola’s cell (mobile) phones give a whole new meaning to “sound in motion.”