Category Archives: Uncategorized

Casting About

Hello Fellow MIST-ery Men, Women and Children,

We are still steaming towards Taiwan at a steady 10 knots. This has been a long transit (9 days so far), so we have been taking turns presenting our research every night. We have a variety of research disciplines represented on this cruise, and it has been very interesting to hear about the work that each person is doing and how it relates to our cruise’s research aims. Last night Jensen Jacob from the Earth Observatory of Singapore (EOS) presented some of his work on mapping the tectonics of the ocean basins near Indonesia and Australia. Continue reading

Under Pressure

Hello Fellow MIST-chief Makers,

The science portion of the cruise wrapped up a couple days ago, and we have all been resting and catching up on some well-deserved sleep. We are now in transit, heading for our final destination of Kaoshiung, Taiwan. 10 days of transit (~4 left!) is a long amount of time, so to keep entertained we have all been reading, working on papers, playing ping pong (Sylvain was crowned champion of the MIST Open), cards, and other board games. We also recently held a trivia night, with categories ranging from ‘Leviathans of Literature’ to ‘Roger Revelle: The Man, The Ship, The Legend.’ Continue reading

Tsunami day – a memory from Sri Lanka

Imagine, its 4:30am, 26th December and you wake up on the floor in a fisherman’s house on the Sri Lankan coast. It is still pitch black, with only candles lighting up the room. The smell of the smoke of burning wood comes from the kitchen. Don’t remember booking this holiday package? Oh yeah, it was a failed attempt to sleep on the beach in a shelter for fishing nets. You and your friend got discovered by Chamil and then invited to stay with his family for the night. Continue reading

A brief history of underwater acoustics: Part I

It’s amazing to think that while we can image individual stars and planets within galaxies millions of light years away (one light year equals ~10^13 kilometers!), we have only recently began imaging the topography of the seafloor that makes up 70% of the Earth’s surface, the very planet we live on!

hello_seafloor

Fundamentally, this is because neither light nor electromagnetic waves can penetrate very far into water, which makes the whole business of mapping the seafloor significantly more difficult than looking at the stars. So while explorers like Copernicus and many others before him have been peering into the depths of the universe for the past several centuries, it was not until very recently, the last half of the 20th century, that underwater imaging technologies have been developed and used to gaze into the abyss that is the ocean floor.

The initial motivation for such endeavors was militaristic; having the capacity to detect the location of naval vessels, especially submarines, was a critical component of the Allied Forces toolkit developed during World War I and used to defeat the Germans in World War II. The basic concept behind such technology is that acoustic waves, or sounds, travel very far in water before dissipating. Therefore, if you are able to listen to the sounds of the ocean and hear something uncharacteristic, say a ship plowing through the water, you could then try to determine the direction that sound is emanating from. And since acoustic waves are carried for large distances, it is conceivable that a ship, or better yet a submarine, is detectable long before it reaches your position. Today this technology is known as sonar, which is an acronym for sound navigation and ranging.

After such military efforts came to fruition, industry and science communities were able to further develop and apply such methods for their own interests. In particular, underwater acoustics is used to detect and monitor fish populations as well as to map the topography of the seafloor and its subsurface, the latter of which is the basic tenet behind our goals for the MIST expedition.

Look out for Part II in the coming days! And for your viewing pleasure, what exploring the depths of the ocean looks like today.

 -Samer

A Song of Water & Mud

No land for miles and miles

No land for miles and miles  

At around 10:00PM on New Years Eve, the ship arrived on station and we finally got out of the computer lab to get our hands dirty.  By “on station”, I mean that we positioned ourselves at 90E longitude on an oceanic ridge 3100 meters (2 miles) above the seafloor, instead of the usual ~4200 meters (2.8 miles).  Out here in the open ocean it basically looks like we’re in the exact same place, except that now everything is upside down since we’re in the Southern Hemisphere. Continue reading

What do you bring with you on a trip to the moon?

Life on a ship can be stressful when half way across the Indian Ocean, like us, you’re still waiting for your permits to enter Indonesian Waters. So let’s spend some time talking about fun stuff and let’s get a break from politics, international coöperations and ever-changing plans. Let’s talk about what you bring to the moon when you’re one of the lucky guys to go there.

Continue reading

We Have a Winner

A few days ago we started a contest to identify the frequencies used in the multibeam and the chirp.  After what can only be called an unprecedented number of responses I am very happy to announce that Matt Crowne is our winner.  Matt used a program called Audacity (a very cool open source program for playing around with audio) to generate a power spectrum from the MP3 I uploaded and select the correct frequencies.  Matt picked 3.7 kHz for the chirp and 11.6 kHz for the multibeam.  The “official” values are 3.5 kHz and 12 kHz respectively.

Congratulations Matt!

Do you want to win a tee shirt too?  We’ll be starting a tee shirt design contest soon, so check back often!

Robert

Flushing the loo in the Southern Hemisphere

Hurray! We just crossed the equator into the Southern Hemisphere! Everyone has been waiting for this moment in the computer lab, crowding around the screens as the Latitude changed from N to S through a number of zeros. There was no red line to cross or a welcome sign floating. Just an imaginary line imposed on the surface of the vast ocean and us with our numbers.

Roger Revelle crosses the equator!

Roger Revelle crosses the equator!

The ocean has been relatively calm as if welcoming us with a warm embrace. Or perhaps it is just a front, beckoning us deeper into the heart of the ocean only to swallow us into the storm of storms (Luck seems to be on our side looking at the sea state predictions – guess Poseidon likes us). We are approaching our first waypoint where we will survey the area for an ideal location for a gravity core so hopefully Poseidon stays with us. So, now that we are in the Southern Hemisphere, which direction will the flush of the loo go? Clockwise or Anti-clockwise?

Joyce

Joyce’s birds & a contest

As Joyce pointed out in her post the sounds of the multibeam and chirp system can be heard in most places on the ship and are now are constant companions.  I was able to record the sounds in a relatively quite passageway on the ship (using my cell phone believe it or not).

knudsen_em122_waveform

This image shows part of the waveform of the audio I recorded.  There are three pulses, the first and last are the Knudsen chirp and the middle pulse is the EM122 multibeam.

Below is the full audio, 3 chirps with the multibeam between chirps 1 and 2.

The multibeam can be tough to hear because it operates at a higher frequency than the chirp, so I slowed it down by 4x.

Here is the chirp, also slowed down 4x, just because it sounds cool.

And now for a challenge:  Take the mp3 with the chirp and multibeam pulses from above and figure out what frequencies the chirp and multibeam operate at.  The source is noisy so lets say that you need to be within 20% to get the answer right.  First one to post the correct answer wins a tee-shirt.

Robert Petersen

Fine print:  If you already know the answer then you can’t play.  You need to use the sound file to get the answer don’t look up the specs.  Also I’m in international waters so I don’t have to comply with any of those annoying rules that ‘man’ wants me to.

 

scripps oceanography uc san diego