Water Quality Measurements in the Sea Set the Stage for Outer Space

A multidisciplinary team of scientists is using a Florida coral reef as a testing ground for a bold mission – expeditions to near-earth asteroids, the Moon or Mars. NEEMO-3.jpg

The undersea environment provides many of the same challenges as space exploration – micro-gravity, remote sites, limited communications and the need for remotely operated data gathering platforms.   

The Aquarius Reef Base – a live-aboard underwater mock-up of a space station that has been home to the NEEMO (NASA Extreme Environment Missions Operation) missions for the past decade – is a perfect testing ground for the space agency’s remote science-gathering protocols and practices.    

“You’re always facing new challenges, like the Apollo 13 mission, and also new discoveries that are unexpected,” says Delaware associate professor or oceanography and geology Art Trembanis, a NEEMO veteran and expert in autonomous underwater vehicles (AUVs).

CastAway: New Frontiers

Trembanis’ instrument-loaded AUV works with DeepWorker submersibles and SCUBA divers to collect a wide variety of data in a broad number of ways.    

He strapped a SonTek CastAway CTD to the AUV. The CastAway is a rugged, palm-sized instrument that samples conductivity, temperature and depth, profiling the water column and computing sound-speed readings that aid in correcting a host of underwater sonar measurements.

With a flow-through measurement cell, the durability to operate as deep as 100 meters below the surface, two AA batteries for power, and an onboard datalogger accessed at the surface via Bluetooth, the CastAway is completely self-contained – a perfect fit with the NASA concept.    

The initial point of strapping CastAways to the DeepWorker submersibles was to simply gather data for the sake of the drill. However, Trembanis notes, the precise location data from the CastAway helped the team better analyze video footage collected by the submersibles, which could aid in his ongoing study of barrel sponges. Also, the sensitivity of the CastAway yielded insight into the spatial relationships among water masses of different salinity and temperature along the reef.      

“There aren’t big differences, but shades of grey can be significant in the reef environment,” he points out.

EXO2 Sonde Goes Deep

Trembanis also outfitted the DeepWorker submersibles with the EXO2 multiparameter advanced water quality monitoring platform.NEEMO-2.jpg

Designed for use as deep as 250 meters – well beyond NEEMO mission parameters – the EXO2 measures pH, dissolved oxygen (DO), temperature, salinity, turbidity, depth, total algae (using a dual-channel sensor for chlorophyll as well as a phycocyanin sensor for blue-green algae), and a fluorescent dissolved organic matter (DOM) sensor.          

Trembanis was enchanted by the possibilities created by the EXO2. Immediately, he recognized the opportunity to give NASA pilots a mission while gathering valuable data about the water dynamics in and around the mysterious barrel sponges that dot the reef.

“At the end of the day, we could connect it to the laptop via Bluetooth and transfer all our data files,” Trembanis says. “We could look at the data on the laptop while someone else was cleaning the unit.

“We changed the batteries every day just to be safe, though the sonde could run for days on a set of batteries,” he notes. “We had it running continuously for five or six hours a day at its maximum rate, and it was already loaded with plenty of memory – turns out we could have conceivably set it up to run for weeks.”

Photo captions:

Art Trembanis displays the orange CastAway CTD and blue EXO2 multiparameter sonde that added sophisticated data-gathering capabilities to the NEEMO 16 mission and proved the remarkable versatility and convenience of both instruments.

A YSI EXO2 multiparameter sonde provides an intimate look at water quality parameters inside a barrel sponge off the coast of Key West. See video below of sponge science with the EXO sonde.


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Additional Blog Posts of Interest:

Monitoring Water Quality Interactions with Multiparameter Sondes

10 Tips to Prevent Biofouling on Water Quality Instruments 

Top 5 Challenges to Collecting Water Quality Data - Challenge 1

Advantages of Smart Sensors and Ports on Water Quality Sondes

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