Sink or Swim!

You know the feeling when you finally program your robot to autonomously move forward, turn left, locate a CASCADE EFFECT ball, and then pick it up all on its own? Then you travel to your next FTC competition and your robot is off! Without a hitch! Have you ever wondered how this amazing skill you now possess will benefit you in the future? The Deep Phreatic Thermal Explorer (DEPTHX) is basically a very, very advanced FTC robot constructed with the goal of creating a vehicle that could travel and explore the underwater oceans of Jupiter’s moon, Europa.  

 The Deep Phreatic Thermal Explorer (DEPTHX) is an autonomous underwater vehicle that was designed and built by Stone Aerospace, an aerospace engineering firm from Austin, Texas. It was designed to autonomously explore and map underwater sinkholes in northern Mexico as well as collect water and wall core samples. The DEPTHX vehicle was the first of three vehicles to be built by Stone Aerospace, which were funded by NASA with the goal of developing technology that can explore the oceans of Jupiter’s moon Europa to look for extraterrestrial life.

DEPTHX was a collaborative project; Stone Aerospace worked with Carnegie Mellon University, which was responsible for the navigation and guidance software, the Southwest Research Institute, which built the vehicle’s science payload, and research scientists from the University of Texas at Austin, the Colorado School of Mines, and NASA Ames Research Center.

This underwater vehicle underwent several different design concepts over a few years as engineers at Stone Aerospace explored various options. The elliptical shape came about after it was realized that the round shape would be beneficial when the vehicle was trying to maneuver tight spots in unknown territory. The scientists and engineers also did field work at Cenote Zacatón in Mexico to acquire data for the software team which also contributed to the design changes. The final design was decided in 2006 and construction began.

The completed vehicle was approximately 7 feet in diameter and weighed 3,300 pounds. It had redundant navigation systems including 54 sonars, an inertial measurement unit, Doppler velocity logger, as well as depth gauges and accelerometers. Propulsion systems were also redundant, having six thrusters and two equivalent battery stacks. It was outfitted with a variable buoyancy system, and finally with the science payload that included the ability to take in water and solid core samples for later analysis, as well as an onboard microscope to analyze water samples in real time.

During the DEPTHX 2007 deployment, the vehicle was able to create 3D maps of four cenotes in Sistema Zacatón in Tamaulipas, Mexico. This was the first autonomous system to explore and map a subterranean cavern. The mapping of Cenote Zacatón was particularly notable because its depth was previously unknown, human divers had not yet successfully reached the bottom of the cavern. DEPTHX created the first map of the bottom of the Zacatón, which has a depth of over 1,000 feet. DEPTHX was the first robotic system of any kind to implement three dimensional simultaneous localizing and mapping (SLAM). It was also the first such system to make its own decisions on where and how to collect samples. From these samples at least three new divisions of bacteria were discovered.

The success of the DEPTHX mission led to the funding of the following project, ENDURANCE. The ENDURANCE vehicle reused the frame and a number of systems from the DEPTHX vehicle, but was redesigned for optimal function in the Antarctic environment.

References:

http://www.frc.ri.cmu.edu/projects/depthx/index.html

http://en.wikipedia.org/wiki/DEPTHX

http://science.howstuffworks.com/environmental/earth/oceanography/depthx.htm