Cryobot

Abstract: One of the more likely places in the solar system for the existence of extraterrestrial life forms is the Jovian moon Europa. It has been postulated that a volcanically-heated ocean is likely to exist underneath Europa's icy surface. If a detailed remote-sensing reconnaissance of Europa determines that an ocean does exist under the ice, then in- situ measurements will be needed to directly explore the Europan ocean and the ice that lies above it. In order to make quantitative measurements of the Europan environment, a lander spacecraft capable of penetrating the surface ice layer by melting through it is proposed. This vehicle, dubbed a `Cryobot', will be designed to carry a small deployable submersible (a `Hydrobot') equipped with a complement of instruments. The design of an instrument package to search for life across the wide range of thermal and pressure environments expected on Europa, the issues in sample handling, and long-term reliability for a potential multi-year transit through the ice all present difficult design issues. Opportunities for performing investigations of deep, submerged Antarctic lakes on Earth are described which would test the Cryobot/Hydrobot system while collecting intrinsically valuable terrestrial science data.© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Abstract: The Cryobot team at JPL has been working on the design of a Cryo-Hydro Integrated Robotic Penetrator System (CHIRPS), which can be used to penetrate the Mars North Polar Cap or the thick sheet ice surrounding Jupiter’s moon, Europa. The science for either one of these missions is compelling. For both Mars and Europa the major scientific interest is to reach regions where there is a reservoir of water that may yield signs of past or extant life. Additionally, a Mars polar cap penetration would help us understand both climatic and depositional histories for perhaps as far back as 20 million years. Similarly, penetration of the Europa ice sheet would allow scientists to unravel the mysteries surrounding the thick ice crust, its chemical composition, and subsurface ocean properties. Extreme mass and power constraints make deep drilling/coring impractical. The best way to explore either one of these environments is a cryobot mole penetrator vehicle, which carries a suite of instruments suitable for sampling and analyzing the ice or ocean environments. This paper concentrates on a Europa deep ice (i.e., kilometers thick) application of the CHIRPS, and introduces the reader to the vehicle design with focus on the use of radioisotope thermoelectric generator (RTG) technology as the primary heat (1 kW total) and power source for the robotic vehicle. Radioisotope heater unit (RHU) milli-watt power systems (120 mW total) are also employed to power the mini-radiowave ice transceivers, which are used to relay data through the ice up to the surface lander. The results of modeling and design work for both of these areas are discussed in this paper. Although radioisotope power is baselined for the Europa flight version of the cyrobot, no decision on the final design of the cryobot will be made until the environmental review process is complete. Any use of the cryobot for Mars or Europa will conform to all environmental and planetary protection requirements.

Abstract: Several studies have been conducted to design robotic exploration vehicles for investigating a sub-surface water ocean within Jupiter's moon Europa. The current data from the Galileo spacecraft indicates a possible sub-surface ocean of undetermined depth covered by a water ice crust on the order of 10 kilometres thick. The ice crust also flexes several tens of metres every Europan day due to tidal forces. This presents several design challenges, especially for the communications link back to the science team on Earth. This paper presents the modeling and analysis for a communications system that uses transceivers embedded within the ice crust. The work was done for a design study that examined using ice-embedded transceivers to communicate between a deep ice penetration "cryobot" at the liquid water ocean and a communications package on the Europan surface. This paper focuses on the microwave properties of ice and the communications link margin analysis.

Abstract: A 2007 Mars North Polar Cap penetration mission is being proposed under the Mars Scout Discovery Program. The Cryobot robotic mole vehicle being developed by a team of JPL engineers would penetrate 200 meters below the polar ice cap in the only known accessible reservoir of water on the planet. The probe would be manifested with a suite of science instruments which will (1) examine the climatic history of Mars as reflected in the layers of ice-the Mars Surveyor Orbiter Camera (MOC) has revealed exciting images of the polar ice cap indicating the layers to be of the order of 1 to 100 meters thick; (2) look for organics and bio-signatures potentially transported via wind and trapped in the ice; (3) examine trapped minerals and understand the chemical make-up of soluble constituents; and (4) provide the first-ever polar cap surface images as well as characterize the polar cap meteorology. Although radioisotope power is baselined for the Mars '07 version of the Cryobot, no decision on the final design of the Cryobot will be made until the environmental review process is complete. Any use of the Cryobot for Mars will conform to all environmental and planetary protection requirements.