Ask-a-Scientist, Part V: Styrofoam Cups & Crushing Pressure

Thanks to Mr. Perry’s seventh-grade science classes at Rippowam Cisqua School in Bedford, New York for sending us some questions. Mr. Perry was my science teacher in seventh grade and it was great to be able to connect with some students at my old school!

What led to the discovery of the Styrofoam cup being crushed at deep depths? Who came up with the idea of the Styrofoam cups being used?

I don’t know what exactly led to the discovery of Styrofoam being crushed at deep depths, but humans have known about the extreme pressures underwater for a long time. We also don’t know when exactly the tradition of shrinking Styrofoam cups began, but it’s certainly a long-standing and much-loved one among oceanographers! Styrofoam was invented in 1941 and by the time Barney Balch started going to sea in 1978, crushing cups was already a well-established activity on board research vessels. So, the tradition had to start somewhere between there.

Why were you using Styrofoam cups if they are bad for the environment?

That’s a great question! One of the problems with Styrofoam from an environmental standpoint is that it doesn’t degrade after it’s been introduced to an ecosystem or placed in a landfill. Since we’re keeping the cups after we shrink them, we don’t have to worry about that. Also, some of the people on board who have been going to sea for a while pointed out that as more and more places have banned the use of Styrofoam, it’s getting harder and harder to find cups for us to shrink. So maybe someday soon we’ll have a different collection of shrunken items we use to demonstrate pressure!

A man in a salmon-colored t-shirt and a blue mask is resting his arms on a yellow metal frame.
Unlike Bigelow scientist Bruce Bowler, the CTD can withstand the pressures of the deep ocean. While humans usually only go to about 20 meters depth (with a basic scuba diving certification), the CTD went down to 5100 meters on this cruise!

How does the equipment that you used to get the Styrofoam cups 5100 meters into the water withstand the water pressure?

All of the equipment we send down into the water has gone through extensive testing to make sure it can withstand the ocean’s pressure. Some of the sensors are only rated to go down to 1000 meters, so we had to remove them from the CTD frame every time we did a deeper cast than that. And for some of the sensors, we have spares on board that we can replace if anything were to malfunction.  

After the Styrofoam cups were 3 miles underwater they were crushed and all the air was sucked out of them. How far underwater would a human have to go to have this happen to them?

A basic scuba diving certification allows you to go safely to a depth of about 60 feet (18 meters). The record for scuba diving is nearly 1,100 feet (332 meters) — still a long, long way above the ocean floor (at least where we were)!

Two people are standing at the back of the boat with a calm ocean behind them. Both are wearing high-visibility work gear; one has on an R2-D2 beanie while the other is sporting a camouflage hard hat.
Scripps chemist Melissa Miller and research technician Matt Durham prepare to launch one of the last SOCCOM floats of the cruise.

Who invented the Hawk-eye [SOCCOM float]?

Scientists developed the predecessor to the SOCCOM floats in the early 1990s and have been refining the design since then. The first floats, called ALACE floats, only measured temperature. These were designed at Scripps Institution of Oceanography. The next iteration of floats was the Argo network — these are still being deployed all around the world! They have the capability to measure temperature and salinity, as well as depth.

Scientists developed the predecessor to the SOCCOM floats in the early 1990s and have been refining the design since then. The first floats, called ALACE floats, only measured temperature. These were designed at Scripps Institution of Oceanography. The next iteration of floats was the Argo network — these are still being deployed all around the world! They have the capability to measure temperature and salinity, as well as depth.

The SOCCOM floats are an upgraded version of these earlier floats. They’re equipped with more sensors that let scientists look at biological and chemical quantities in seawater. These extra sensors are added onto the basic floats at the University of Washington before being shipped off around the world for deployment. (To answer another student’s question, Mr. Wynar’s class named Hawk-eye after the pair of nesting hawks at their school, not the Marvel character.)

How much pressure can the Hawk-eye [SOCCOM float] withstand?

Over their lifetime, SOCCOM floats cycle from the surface to a depth of 2,000 meters. For every 10 meters of water depth, the float feels an additional pressure equivalent to that of earth’s atmosphere, so the pressure at that depth is about 200 times greater than at the surface! However, the floats are also designed with a safety factor so they won’t just immediately crumple at 2,001 meters. I’m not entirely sure what that safety factor is, but it’s likely around 25–30% above the pressure it’s rated for.

We also deployed two floats called “Deep Solo” floats for NOAA (the National Oceanic and Atmospheric Administration) on this trip. The deep solo floats can withstand the pressure at a depth of 6,000 meters below the ocean’s surface!

A person with a buzzed hair and a white-and-blue Hawaiian print shirt is drawing on a black metal cylinder contained within a plywood box.
Early on in the cruise, scientists were asked to pitch in to help decorate the SOCCOM floats. Here, Giuliana decorates “Hawk-Eye”, named after St. Elizabeth’s school mascot.

How do all of these sensors play their part and are there any mistakes with the sensors? What would happen if the Hawk-eye malfunctioned?

All of the sensors equipped on SOCCOM floats have been tested extensively, but errors do happen, of course. The ocean is a very harsh environment — especially for electronics! However, since the cost of running a research vessel is so high, we are unable to retrieve malfunctioning floats unless there happens to be a ship nearby when the errors occurred.

Giuliana Viglione is a journalist and science communicator who has joined Senior Research Scientist Barney Balch’s research cruise to study the impact of coccolithophores in the Southern Ocean. On board the ship, she’ll be helping the team carry out experiments, document the research cruise, and conduct educational outreach with students across the country. She can be reached at giuliana.at.sea@gmail.com.

Ask-a-Scientist, Part V: Styrofoam Cups & Crushing Pressure
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