The purpose of this years field test was to determine basic physical-acoustical ice parameters, especially the frequency dependency of the acoustic extinction length, as a basis for the system design of the acoustic sensor network and to perform a first in-situ test of a new melting probe prototype.
The field test was carried out in August 2015 on Hintereisferner in Austria. The test was kindly supported by the Institute of Atmospheric and Cryospheric Sciences situated at the University of Innsbruck. The Hochjoch Hospiz was used as base station.
The research team, which worked on Hintereisferner over a period of nine days, consisted of six scientists from Physics Institute III B, RWTH Aachen University and two scientists from the institute cluster IMA/ZLW & IfU, RWTH Aachen University. The first day was dedicated to the safety instructions for glacier novices as well as the exploration of the glacier, which was supported by Stephan Galos (Institute of Atmospheric and Cryospheric Sciences, University of Innsbruck). On the basis of his long lasting experience the scientists picked a suitable test site and took its GPS coordinates for the helicopter flight. On the next day the required measurement equipment was transported to the test site by helicopter. The first melt tests were performed parallel to the setting of the glacier camp. During the following six test days the scheduled measurements were carried out. In order to deploy the measurement equipment within the glacier the scientists needed to melt several measurement channels with a depth of up to 5m. For the acoustic measurements an emitter was placed in one of the measurement channels and a receiver was placed in a second measurement channel. The distance between emitter and receiver was varied by using different combinations of the measurement channels. The maximum distance between emitter and receiver was 100m. In addition the depth beneath the glacier surface was also varied. In parallel, further tests were performed with the melting probe prototype. In particular a 30m deep channel was melted and a melting velocity of about 2m/h was determined. The glacier exploration was also continued. When all measurements were finished the measurement equipment was removed from the glacier and transported back via helicopter.
In summary one can say that the field test on Hintereisferner was successful and the scientists were positively surprised by the good conditions at the test site. The cooperation with the University of Innsbruck was a great advantage since the test site was completely unknown to the research team prior to the test campaign. Preliminary data analyses show good results.
Proceeding at a velocity of one metre per hour and at an angle of 65 degrees, a special probe, the so-called IceMole, slowly melts its way towards its target at a depth of 16 metres: a crevasse in the Taylor glacier which conveys the so-called brine, subglacial water from the lake below the glacier, to its outlet in the Lake Bonney. Thus, scientists succeeded for the first time ever in taking an uncontaminated sample of subglacial water and bringing it to the surface using a melting probe from Aachen University of Applied Sciences. This was enabled by the Enceladus Explorer (EnEx) project mounted by the DLR Space Administration. What has succeeded at the Antarctic Blood Falls on Earth will be duplicated on the Saturnian moon of Enceladus at a later date. For this purpose, the EnEx initiative will be continued beyond the year 2015.
Editorial: DLR Raumfahrtmanagement / DLR Space Administration
Title: Exploration EnEx – Vom Südpol zum Enceladus
Pages: 6 – 13
EnEx probe Collects First Clean Water Sample from Blood Falls in Antarctica
Since the first traces of liquid oceans under the thick sheets of ice on some moons in the outer solar system, there has been speculation about whether independent life could have developed there. With this in mind, Saturn’s small moon, Enceladus, is of particular interest, as it spits water particles into space from crevices on its south pole. The NASA Sonde Cassini was able to find evidence of simple organic compounds in the particles. A land mission to investigate this water resources was a decisive step in answering the question about life there. The remoteness and extreme conditions pose a particular technical challenge to future space missions.
The Enceladus Explorer, EnEx, project, initiated and funded by the German Aerospace Center, DLR, has made an important first step in which scientists from six German universities have come together to form a team. The goal of the EnEx project was the development of key technologies for retrieving an uncontaminated water sample on Enceladus, the investigation of mission scenarios, and as realistic a test as possible of the developed technologies on Earth. This field test was conducted in collaboration with American scientists, whose project, MIDGE, Minimally Invasive Direct Glacial Exploration, was simultaneously funded by the American National Science Foundation, NSF. The goal of the joint MIDGE/EnEx project was to extract the first uncontaminated subglacial, that is from under the ice, water sample from Blood Falls, Antarctica.
A crucial key component for such a mission is an ice-melting probe that can be directed and navigated freely through the ice and is able to „see“ through the ice and know its exact position. The necessary navigation technology has been developed in the past three years by experts at at FH Aachen, RWTH Aachen, TU Braunschweig, the University of Bremen, Bundeswehr University Munich, and the University of Wuppertal, and a melting probe, the EnEx-IceMole, was developed at the Department of Aerospace Engineering at FH Aachen and integrated.
The team has now successfully extracted an uncontaminated water sample for the first time from a depth of 16 meters of ice at Blood Falls. The American scientists are currently analyzing the sample, suspected to have been isolated from the outside world for over one million years with the microorganisms inside, which have adapted to the extreme conditions.
A particular challenge was classifying the field test area as international specially protected area, ASPA or Antarctic Specially Protected Area. This involved very strict restrictions and required the probe to be sterilized step-by-step multiple times. This is also absolutely necessary when it is used in space in order not to contaminate the ice moon with terrestrial microorganisms.
The EnEx partners have demonstrated that developed technologies fundamentally work and can be potentially used on Enceladus.
RWTH Develops Ultrasound Systems for Navigating the Drill Probe
Under the direction of Univ.-Prof. Dr.rer.nat Christopher Wiebusch, RWTH scientists at the Institute of Physics III developed and built the ultrasound systems for navigating the drill probe in ice. With the help of elapsed time measurements of sound signals sent from the surface of the ice, the position of the probe can be determined within a few centimeters. The structures additionally enable imaging of the area ahead in the head of the probe, similar to ultrasound equipment in medical technology.
Project coordinator Christopher Wiebusch: „The successful sample extraction is a crowning moment of three years of hard work, where we had to find our way in completely new interdisciplinary surroundings outside of our actual field of research, elementary particles. His colleagues Dipl.Phys. Dirk Heinen is enthusiastic about the experiences from the field test: „Research in the extreme surroundings of Antarctica is a challenge and was a unique personal challenge for me.“
The RWTH physicists are already planning the continuation of the successful project. The focus is on the necessary autonomy of the navigation methods in the extreme glacial surroundings. The physicists are collaborating with the RWTH cluster of institutes IMA/ZLW & IfU under the direction of Univ.-Prof. Dr.rer.nat. Sabina Jeschke: „The plans for the new RANGE project have come quite far. With a new approach we have accomplished robust navigation for examining unknown glaciers and extraterrestrial ice structures.“ A junior research group is also being established in the RWTH Aachen AICES graduate school, which is focusing on the modeling and simulation of contact melting processes with regards to control and regulation optimation. Dr. Julia Kowalski is head of this junior research group.
The Enceladus Explorer Projekt at RWTH Aachen is financed by the Space Administration with funds from the Federal Ministry of Economy and Technology.