Thursday, September 14, 2017

Dreams of Cassini's Demise

By the time I’m done with breakfast tomorrow, the joint NASA/ESA mission to Saturn, Cassini, will be over.  I’ve been enthusiastically following its progress from before its arrival at the Kronian System in 2004. I remember clearly my awe at some of the first pictures of this spectacular, pale yellow-green-brown giant, Saturn at crescent, Saturn eclipsing the sun and setting fire to its rings, Saturn from above, alone against what appears as an empty inkiness behind.  Too, I could barely contain myself -- and entirely neglected my job -- as I followed on my work computer the progress of the Huygens probe’s descent to the surface of Titan as a strangely familiar yet utterly alien world unfolded before me.  These early outcomes captured me irretrievably and, across these last 13 years, the Cassini mission has become part of my day-to-day reality.  In a few hours, that will, as all things must, come to an end.

If you’ve followed the mission or any of the recent popular science pieces on it, you know that the probe is being dropped into Saturn’s atmosphere to protect the moons Enceladus and Titan from any potential contamination:  these two worlds, in very different ways, proffer two of the solar system’s best candidates for extraterrestrial life and scientists hoping for future missions to explore them wish to minimize the chance that any life found comes from us.  So, the solution is to crash the probe on Saturn, which shows every indication of being entirely inhospitable to life as we understand it.

In all of the articles I’ve read about this, the story ends with the loss of signal from Cassini and perhaps descriptions of scientists shutting down computers, turning off monitors, rolling chairs under desks, and walking out of Mission Control to drink a solemn toast to a collective job well done.  But Saturn, while unwelcoming to life, is far from dead; it is a rich, complex, and almost unimaginably vast system, a churning, roiling, rapidly rotating ball of gas -- with a (relatively) little bit of rock.  What happens to Cassini after transmission ceases?  This has been a fascinating question to me and a little reading and Googling has yielded some interesting possible answers; here is what I imagine based on what I found.*

Science journalists describe Cassini’s last waking moments:  edging into Saturn’s upper atmosphere at tens of thousands of miles per hour, it begins to be buffeted and tossed about.  Its aerodynamics pull it to begin to tumble, but its stabilizers, at first, keep its antenna pointed at Earth, but this does not last long.  In short order, the crashing of the wisps of gas at horrendous speeds pummel the craft until its ability to direct itself -- designed for near-vacuum -- is overwhelmed and Cassini tumbles and (some light-minutes further/later) Earth loses its signal.

Almost immediately after this, as the drag on Cassini brings it ever more quickly into thicker and thicker air, the probe begins to break up, heat up, and vaporize.  Different parts will presumably respond differently to the atmospheric insults and, as bits break off and apart, some will slow more quickly than others, and what remains of Cassini will, after probably no more than a few dozen seconds, slow and cool enough to become a minor rain of detritus falling into Saturn’s cloudtops.  I imagine some of these as relatively light pieces of framework or housing, unmassive enough to decelerate rapidly enough to avoid completely vaporizing, as well as various chunks of dense, durable stuff -- the most formidable of which might be whatever remains of Cassini’s power core:  66 pounds of plutonium.

As these bits variously plummet, tumble, or float their way into Saturn’s depths, they will pass first through its upper layers with clouds of ammonia and water ice and bands of ammonium hydroxide.  As pressure in these upper layers increases, water can form droplets and mix with ammonia.  Saturn is, however, by far mostly hydrogen and it is through this that Cassini’s remnants will pass for a very long time.  The outer layers are gaseous hydrogen, but, as pressure increases, this becomes liquid and, eventually, metallic hydrogen.  As the scattered bones of Cassini works their way down through the gas and liquid hydrogen, its densest pieces may come to rest somewhere around the transition from liquid to metal, some 18,000 vertical miles from where it sent its last radio pulse.

Think about this:  Earth is about 7,900 miles in diameter; that means that the shards of Cassini could fall through two and a half Earths before stopping.  For how long will they fall?  Years?  Decades?  Centuries?  Millenia?  Just imagine...

One question I didn’t get an answer to (mine was not an exhaustive search) was at what point might different parts float -- particularly the plutonium?  Metallic hydrogen can, in theory (at least as I understand the lay descriptions), exist as a liquid under sufficient pressure:  would plutonium float in this ocean metal if it made it down that far?  Or would it continue falling?  Down, down below inconceivable depths of the most abundant constituent of the universe, there is probably a hunk of iron, nickel, and rock:  Saturn’s core.  might the densest pieces work their way through the metallic hydrogen, all the way down to stone?  Also, what (if anything) happens when radioactive material like Cassini’s heart comes in contact with a highly conductive material like metallic hydrogen?  And is it possible -- even likely -- that Saturn’s core already has at least a few dozen pounds of radioactive elements?  The metallic-rocky core may be larger than the Earth:  what would that look like?

In my dreams tonight, I imagine Cassini’s bones wafting through ammonia clouds and currents of liquid hydrogen.  May they find a well-deserved and worthy rest there.

*NOTES:  This is pure speculation on my part, based on a relatively cursory search of a handful of what I perceive to be relatively reliable sites (e.g., NASA, Wikipedia, etc.).  I’d actually be thrilled if a real planetary scientist did this thought experiment!  Also, I normally hyperlink my essays extensively, but, tonight, I'm sleepy and actually just proud I got this written and posted.  I invite anyone to explore and/or correct any of the facts I list or ideas I have shared.

Thursday, August 24, 2017

Memories of Andrew

I got a text today from my brother, Matthew, reminding me that it was 25 years ago today that Hurricane Andrew made landfall in South Florida.  He and I were there to witness the event and lived in its aftermath.

I first heard about the storm’s threat the Saturday nine days before (Andrew came through on a Monday night) while I was at a seminar in Boca Raton.  Matt had been staying with me for only a few days, having just relocated to Miami, where I had lived for several years.  At that point, the storm’s prediction cone was pretty wide and best guesses took it north of my apartment on South Beach.  By the next Sunday, it had narrowed in on Fort Lauderdale, less than an hour north of us; to escape the destruction, we could either go well north -- we had relatives in Tampa -- or a little south.  We decided on south.

At the time, I was working as a massage therapist at an acupuncture clinic run by the wife of a mentor of mine; they were kind enough to let Matt and me join them in their apartment to ride out the storm.  All day Monday, Matt and I moved furniture, emptying my east-facing living room and placing as many of my possessions as possible on high shelves in closets in my first floor apartment.  In the evening, we headed down to South Miami, where my boss, Marlene, and my mentor, Bob, lived.  I remember putting my two young kittens, Kylie and Ashoka, in an empty office at the clinic around the corner, as the apartment building allowed no pets; I was really anxious to leave them, but I had no better place.

Safe in the apartment -- old Coast Guard housing converted to condos -- we awaited Andrew’s wrath, watching the green, computer-animated avatar of its wind and rain bear down on us via the local news until we lost power.  At one point, a large picture window in the living room bowed back and forth frighteningly while we put cardboard over it (being an upper story apartment, the usual prophylactic of putting plywood over the outside had been prohibited), but mostly, for us, the storm passed with little more than -- at times unnerving -- noise from wind and rain.  We remained awake until the small hours of the morning, eventually heading to sleep around three or four.

Probably due to nervous energy, we were up again by eight; the wind and rain had largely died down, the sky was cloudy but light, so we ventured out.  As relatively underwhelming as our experience of the storm from inside the apartment had been, the impact on the world outside was overwhelming:  we emerged into what felt like an entirely different world.  We could only be awestruck.  The lush, subtropical paradise of South Miami had been razed such that almost nothing stood more than about a dozen feet high.  Woody deciduous trees were snapped in mid-trunk, their crowns tossed aside like incompleted model train landscape decorations.  A neighbor’s ancient and expansive banyan tree had, over the years prior to the storm, entangled his favorite chair in its aerial roots; Andrew had stripped the tree of its leaves, uprooted it and tossed it back in the yard on its side like a great squat barbell, the owner’s chair still comically clinging, otherwise undisturbed, in the roots.  Power lines and poles littered the streets and cars were buried under detritus.  Palm trees stood like great phalluses lining the streets, shorn of their leaves, the only things of any height remaining.

We learned later that Andrew had not gone north of us, along the Dade/Broward county line, as predicted, but instead had turned suddenly south, with the deadly northern eyewall passing perhaps a dozen and a half miles south of us:  instead of moving further from the storm, my brother and I had come closer.  Indeed, only about a mile south of Bob and Marlene’s, the damage became significantly worse.

I don’t recall where I had stored my car, but it was undamaged.  By mid-day, I heard reports that authorities were letting residents back onto Miami Beach, so, expressing our gratitude to Bob and Marlene for their hospitality and the safety it afforded us, Matt and I retrieved my lonely kittens and attempted to make our way back home.  The drive was a post-apocalyptic steeplechase through downed trees, power lines, and billboards, with neighbors walking about, half-stunned, inspecting the damage and other drivers attempting to wend their way through the newly created maze.  As I recall, it took a few hours, but eventually we were able to make it back to Miami Beach via a causeway north of the route we normally took.  Streets were swept with sand shoals and piled with verdant wreckage.  Working our way south, we were forced to take residential and side streets, which were often blocked by fallen trees, but neighbors were already out in force, clearing sidewalks and roads of branches and trunks; we took part in several efforts that required chainsaws and teams of muscle.

When we finally made it home, we were astonished to discover that a single pane of the jalousie windows had worked loose, leaving a narrow opening for Andrew to deposit a small puddle of muddy water on the living room floor; the rest of the apartment was as we had left it.  We quickly went to work restoring the space to its former condition.

Over the next week, we had many experiences that told of how much our corner of the world had been upended.  Matt and I went to help a friend who lived in one of the neighborhoods where the damage had been more severe.  When we arrived, there was more roofing tile on her lawn than remained on her roof.  We found her in her flooded sunken living room, pathetically scooping water into a kitchen trash can with a measuring cup.  We spent the day with her, mostly picking up Spanish tile and emptying her new in-living-room pool.

Another day, a kid in my neighborhood, previously a stranger, invited us to his uncle’s house in Coconut Grove, a very wealthy suburb on the mainland:  having been out of power for three days, the meat in his freezer had thawed and he was cooking it all on his barbecue and serving it to anyone who would come.  We ate well -- and gratefully, as my own, much more modest, larder had been similarly compromised.  While there, I took a walk around the neighborhood and I stumbled upon a 35’ sailboat, still attached to its pier, a good hundred yards inland from the bay.

I was an avid cyclist during the years I lived in Miami and one of my favorite places to go was Key Biscayne; the route was a nice, eclectic 30 mile out-and-back from my apartment.  I had heard that the park at the south end of the island had been particularly badly hit by the storm.  When I finally made it down to see for myself, I felt as devastated as the land looked.  What had been rich, green, breezily swaying acres of Australian pine and palm trees, in which bright yellow and brown, tea-saucer-sized spiders wove glistening four-foot wide orbs, had been mown down to a height of no more than six feet.  I could stand on my bike at the park entrance and see, across an immensity of jagged, graying, desiccated stumps, down to the cape of the island.  I felt shocked as if I were a bug stumbling out of a field of wildflowers into someone’s lawn.

City-sized changes took place overnight:  with thousands of houses suddenly unfit for living, entire communities relocated instantly, many permanently.  This created traffic snarls like I had never seen:  an infrastructure that had grown organically over decades suddenly functioned like it had been imported unmodified from another, entirely different city.  By the time, a week or two later, when enough of the city was functioning that most of the inhabitants were returning to work, long stretches of previously fluid expressway were turned into rush hour parking lots, while others seemed abandoned.  Drivers got pretty good at four-way stops, since nearly all the city’s traffic lights were dead for days, many for weeks.  Postal service was rendered third-world in its reliability.

Most disturbing for me, though, was Homestead, a town and military base at the south end of the county, bordering the entrance to the Keys.  I had heard that that area had been hit the hardest, with families reporting their homes literally collapsing around them and many residents killed.  It wasn’t until months later that I visited it:  the military base had been abandoned completely and, apparently, suddenly, with yards still scattered with toys and playsets, curtains and blinds hanging raggedly in shattered windows, trees lying dead where Andrew had felled them, some with rusting cars beneath them.  It reminded me of films I had seen of atomic test sites.

The non-military parts of the city were worse:  nearly all the homes there were abandoned, too, but most were in partial or complete collapse and spray painted unceremoniously with contact information for the owners’ insurance companies.  Some properties, by that time, had been scraped clean of wreckage, leaving concrete slabs, with odd bits of plumbing or electrical conduit occasionally reaching up from them, as testaments to a family’s life and Andrew’s power to interrupt it.

Post-storm analyses revealed that Andrew had been a Category 5 storm, rather than the 4 it was estimated as when it hit.  Embedded in its inner tempest were scores if not hundreds of tornadoes, which apparently were responsible for the worst destruction, especially around Homestead.  On the other hand, steady, unchecked wind, can snap stiff, woody trunks, which is why the Australian pines of Key Biscayne and the decorative deciduous trees of Bob and Marlene’s neighborhood were killed, while the bendy native palms with their sacrificial heads grow back, after an awkward, Seussian stage.  Being especially strong, the hurricane’s center held exceptionally low atmospheric pressure within its eye, which lifted up the sea into a roiling hill of a storm surge; vertical forces like this, rather than the horizontal ones, were apparently responsible for events like lifting a pier by the boat tied to it and depositing it whole a football field inland.

I left Miami about eleven months after Andrew.  This is largely coincidence:  although my career was going well and I really loved the city and my apartment, an opportunity arose the next spring that took me to New York City.  My brother had come to Miami to live with me and to heal our estrangement of some years; leaving him behind, as well as a city I loved, was difficult, even as accepting the opportunity felt right.  I sometimes wonder what my life might have looked like had I stayed; Miami still inhabits my dreams.

Thursday, July 20, 2017

Galenean Harp

I've spent a lot of time in the three and a half months since my last post messing around with different parts of my musical/audio instrument collection:  whacking bells, banging on the toy piano, hooking up contact mics to random objects and hitting them, learning how difficult good field recording is, patching miscellaneous objects together in Max and M4L, etc.  I've produced a lot of noise, started a lot of projects, and none of it seemed really to want to go very far -- at least until the last week or so, when a couple of disparate ideas came together and formed this new piece.

It's an ambient work, so you can put it on in the background or you can sit and listen meditatively; I wrote it more with the latter in mind, but it works for the former.  As usual, I recommend good headphones and sufficient volume so you can hear all that's going on (it doesn't get much louder than where it is by the first 90 seconds or so).

This post's title is a reference* to aeolian harps, string instruments that are played by the wind; the central instrument in this piece is a kind of electronic version of that which is "played" by the field recording of waves I made recently.  It's called a resonator; I built it in M4L and gen~, based on an instrument built by a Max programmer (who had, in turn, built his instrument based on a Karplus-Strong synthesizer).  It works analogously to an aeolian harp in that it takes random energy -- in the case of the aeolian harp, wind; in the case of the resonator here, white noise in the form of surf -- and allows tiny samples (effectively grains) to loop in on themselves at specific frequencies and, well, resonate.  The frequencies are, in my version, determined by MIDI pitches, which are programmed by me in an adjacent Live track and fed into the resonator on the audio track through a side channel.  The end result is this sound like waves brushing against open strings, which I just love.

The two additional instruments here are a choir sample pack and Valhalla VintageVerb.  I wanted the choir to remain almost hidden, leading the listener to stretch her ear to hear it.  The reverb fades in very slowly, again, being something you tend to notice only after it's been there a while; I really liked the otherworldly effect it has on the familiar sound of the surf.

Last, a bit on the surf itself:  the waves were recorded among rocks on a stony/sandy beach in Westport, MA early this summer.  I placed my field recorder down as close to the waves as I could get; this yielded the wonderful sloppy, smacking, slapping sounds as the water played around the stones.  The high dynamic range was especially well-suited for use with the resonator, producing the strum-like tones; narrower dynamic ranges tend to produce more organ-like or sustained-string sounds from it.  The stones in the pic accompanying the piece were photographed on the beach as I found them.

*The piece's title is a bit of a pun, in case you hadn't already noticed:  resonances are, by definition, waves.

Monday, April 3, 2017

"Hello Polly! This is your nine o'clock alarm call!"

I've been following Marc Weidenbaum's Disquiet Junto Project for some months now.  I originally discovered it on the lines forum and have made a couple of attempts to participate; in all cases, I did not complete my effort before deadline.  This current piece is the most recent attempt and the only one to see actual (if tardy) completion.  That I finished it is in part due to my enthusiasm for the project:  I have for decades struggled to find the perfect wake-up music and decided now was the time to write some for myself.

It's a simple piece, but I'm very happy with it, for some technical as well as musical reasons.  Technically, I'm pleased that, having identified some mixing issues, I figured out how to resolve them, as well as having gotten a little better with making the granular sampling in the Tuvan voice track work smoothly.  Musically, I like that I was able to incorporate my mother's Coniff bells, as well as some native Live bell samples, and I liked how the voices and the bells worked together.  I was also pleased with how nicely the birds surprise in the end.

The challenge that I've found in choosing music to wake up by is that it must fade in ever so gently -- so as not to scare the piss out of me -- and it cannot have a strong beat; ideally, it would have no beat at all.  For many years, I relied on Pat Metheny Group's "The Bat, Part 2," but my new wife feels that Vasconcelos' berimbau at the beginning sounds creepy.  I switched to Phill Niblock's "A Cage of Stars," which works because of its fade-in and simplicity, but I never listen to the entire 28 1/2 minutes (and, anyway, doing so through an iPhone speaker would be even more criminal than doing so with "The Bat, Part 2").  Weidenbaum's Junto #273 gave the the chance to explore what I really want to wake up to and to create that for myself.

This piece was constructed in Ableton Live using native samples, the wonderful Olympus Elements choir sample pack, AAS's Chromaphone 2 and Valhalla Vintage Verb plug-ins, and two recordings from, along with my personal bell samples, mentioned above.