A cryobot or Philberth-probe is a robot that can penetrate water ice. A cryobot uses heat to melt the ice, and gravity to sink downward. The difference between the cryobot and a drill is that the cryobot uses less power than a drill
Features and technology
The cryobot is a surface-controlled instrumented vehicle that can penetrate polar ice sheets down to 3,600 metres (11,800 ft) by melting. It can be used to measure temperature, stress, ice movement, and seismic, acoustic and dielectric properties. It can also be used for other investigations with remote instrumentation. The probe consists of a hot point for melt penetration, instrumentation for control and measurement functions, two supply conductor coils to link the probe with the surface for transmission of power and measurement signals, and a reservoir section. The probe is filled with a dielectric fluid.
The cryobot was invented by German physicist Karl Philberth, who first demonstrated it in the 1960s as part of the International Glaciological Greenland Expedition (EGIG), achieving drilling depths in excess of 1,000 metres (3,300 ft). In 1973 British scientists in Antarctica performed airborne ice-penetrating radar survey and detected a possible lake. In 1991, the European remote sensing satellite ERS-1 confirmed the 1973 discovery of a large lake below four kilometers of ice, now named Lake Vostok. The lake, which is the fifth largest freshwater lake in the world, is thought to be uncontaminated. NASA was planning to use a cryobot to explore the lake, but ultimately Russian scientists ended up using a drill to reach it on February 5, 2012. The lake’s water, which may have been untouched for 15 to 25 million years, is now undergoing analysis to test for the presence of bacteria.
In 2011, NASA awarded Stone Aerospace $4 million to fund the Phase 2 of project VALKYRIE (Very-Deep Autonomous Laser-Powered Kilowatt-Class Yo-Yoing Robotic Ice Explorer). This project aims to create an autonomous cryobot capable of melting through vast amounts of ice. The probe’s power source differs from many other designs in that it does not rely on nuclear power to generate heat, but rather the power of a high energy laser fed to it through a fiber optic cable. This is beneficial because nuclear probes are not allowed for testing in Antarctica as a result of the Antarctic Treaty. Phase 2 of project VALKYRIE consisted of testing a scaled-down version of the cryobot in Matanuska Glacier, Alaska in 2015. Following the success of these missions, Phase 3 of the project is then planned begin in Antarctica. This phase will use a full-scale version of the cryobot which will melt its way to a subglacial lake, collect samples, and then resurface. It has been proposed to mount a radar on the probe, integrated to an intelligent algorithm for autonomous scientific sampling and navigation.
Stone Aerospace is now integrating their ARTEMIS submersible with the VALKYRIE technology to develop a sophisticated cryobot called SPINDLE (Sub-glacial Polar Ice Navigation, Descent, and Lake Exploration). This third phase of the project would be viewed as a precursor to possible future missions to the icy moons of Europa, a moon of Jupiter, and Enceladus, a moon of Saturn, to explore the liquid water oceans thought to be present below their ice, and assess their potential habitability. 
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