EnEx-RANGE is part of the EnEx initiative, an initiative of the DLR Space Administration. RANGE is an acronym for „ robust autonomous acoustic navigation in glacier ice “ (German: „ R obuste autonome Akustische Navigation in Gletscher-Eis “ ). Participating RWTH institutes are the Physics Institute III B and Institute Cluster IMA/ZLW & IfU.
Intelligent acoustic sensor network
EnEx-RANGE aims to develop an intelligent acoustic sensor network which allows for the navigation of an autonomous probe within an ice volume, e.g. an alpine glacier.
The intelligent acoustic sensor network will consist of separate Autonomous Pinger Units (APU), which are equipped with matched acoustic emitter and low noise acoustic receiver units. The APU carrier system includes a melting system enabling the APU to melt downwards into the glacier. A sophisticated, high performance data system records and processes the sensor data and controls the actuating elements. Furthermore, a reasoning system will carry out a distributed optimization of the sensor network based on its evaluation of current sensor data. Both, automated positioning via two-way acoustic signal exchange and autonomous evaluation of the signal quality is conducted. The latter information is used to determine the accuracy of the positioning and to assure an uniform acoustic coverage of the test area.
Navigation of the EnEx probe
Both the acoustic positioning as well as reconnaissance system developed within the former collaborative EnEx project will be enhanced within EnEx-RANGE.
The acoustic positioning system was developed to determine the absolute position of the EnEx probe based on trilateration. This system is to be adapted to the APU network and will be improved by an increase in sensitivity of the sensor technology. This improved performance will be achieved by the reuse of technology developed for the APU network. Overall this permits a reduction of measurement time while increasing the measurement accuracy. Furthermore, the degree of autonomy will be increased to enable the EnEx probe to act independently. This includes trajectory planning based upon the expected signal quality as well as autonomously initiated re-positioning in case of exceeded error tolerances.
The acoustic reconnaissance system acquires information about the surroundings of the EnEx probe based on sonography. The system emits directive acoustic signals and records the echoes from structural transitions such as obstacles (e.g rock fragments) or regions of interest (e.g. water-fille d crevasses). The data provided by the acoustic reconnaissance system allows generating a map of the fore-filed of the EnEx probe, which can be used for navigation purposes. The sensor technology of the acoustic reconnaissance system is to be optimized to achieve a higher sensitivity as well as an expanded range. Furthermore, a performance enhancement of the electronics will enable an extension of local data processing.
System tests in water and glacier ice
System tests in water and glacier ice are carried out to review the accomplished improvements as well as the self-optimization of the APU network. Since glacier expeditions present a great logistic effort, measurements are conducted in water if possible. Measurements requiring water volumes up to about three cubic meters can be performed in the Aachen acoustic laboratory which is part of the Physics Institute III B. The swimming pool of the Ulla-Klinger-Halle as well as at the Rur Lake at RWTH Aachen Wildenhof venue can be used for e xperiments that require larger test environments. Especially the latter allows for spacious test scenarios similar to the ones planned for the glacier expedition in summer 2017. In summer 2018 the functionality of the intelligent acoustic sensor network in combination with the EnEx probe is to be demonstrated within the ice of an alpine glacier.
The aim of a future Enceladus Explorer space mission is the search for extraterrestrial life on Saturn’s moon Enceladus. To allow for such a mission, new technologies are being developed within the scope of the EnEx initiative of the DLR Space Administration.
Saturn’s moon Enceladus is a promising candidate for the search of extraterrestrial life. Its relative proximity to Earth plus the evidence Cassini provided for both the existence of liquid water, which implies the presence of thermal energy, and the existence of organic compounds makes Enceladus an interesting target for a future space mission. Based on present-day astrobiological knowledge all prerequisites for the emergence of life are present on Enceladus.
A maneuverable melting probe will detect and sample a water filled crevasse beneath the ice surface and conduct in-situ analysis of the recovered sample. To reach this goal several research groups work on different topics within the scope of the EnEx initiative. Currently the following projects are part of the EnEx initiative:
- EnEx-CAUSE, Universität Bremen (Cognitive Autonomous Subsurface Exploration)
- EnEx-DiMIce, RWTH Aachen (Directional Melting in Ice)
- EnEx-MIE, Universität Braunschweig (Magnetic Improvement and Evaluation)
- EnEx-NavEn, Bundeswehr Universität München (Navigationssystem auf Enceladus)
- EnEx-nExT, FH Aachen (Environmental Experimental Testing)
- EnEx-RANGE, RWTH Aachen (Robuste autonome Akustische Navigation in Gletscher-Eis)
The Enceladus Explorer collaborative research project was the foundation of the EnEx initiative. The EnEx project was a research and development project funded by the DLR Space Administration which consisted of six German universities cooperating to develop basic principles for a future space mission.
A scenario similar to the one on Enceladus was tested in Antarctica by probing a water filled crevasse originating from a subglacial water reservoir. Hence an in-ice navigation system was developed which allows tracking of the probe as well as imaging of the fore-field. The so called IceMole, which is a combined drilling and melting probe, served as maneuverable in-ice probe.
For this mission, two acoustic navigation systems were developed alongside conventional navigation solutions. First a positioning system based on trilateration and second a sonographic reconnaissance system based on phased ultrasonic arrays.
In November 2014, the EnEx probe succeeded in taking the first contamination-free water sample from the subglacial lake at Blood Falls in Antarctica. Press release of RWTH, article in the journal Countdown (DLR) and press release of DLR regarding the successful sample taking (press release by RWTH, article in magazin COUNTDOWN by DLR, press release by DLR).
Article on the DLR funding of the Eceladus Explorer Projects.
Information for IceMole development, especially before the time of Enceladus Explorer project are available on Wikipedia.