MSLED: The Micro Subglacial Lake Exploration Device

Abstract

Satellite altimetry and ice-penetrating radar have shown the existence of active subglacial lakes in Antarctica which may have a significant impact on the Southern Ocean and the dynamics of the overlying ice sheet. Understanding how subglacial floods affect ice dynamics is imperative to predicting the effect of ice sheets on rising sea levels, but it is not clearly understood. Furthermore, these encapsulated lakes contain uncharacterised biological ecosystems and serve as analogue environments for future extraterrestrial exploration. To investigate these subglacial environments, the authors developed the Micro Subglacial Lake Exploration Device (MSLED), a unique highly-miniaturised remotely operated vehicle. Equipped with a high-resolution imaging system, as well as conductivity, temperature and depth sensors for in situ measurements, the MSLED is capable of determining geological, hydrological and biological characteristics of subglacial lakes. It was successfully deployed in Antarctica during the 2011-2012 and 2012-2013 Antarctic summer seasons in collaboration with the Whillans Ice Stream Subglacial Access Research Drilling (WISSARD) expedition to Subglacial Lake Whillans (SLW), contributing to the discovery of microbial ecosystems within these environments. The present paper outlines the scientific background behind the mission, the design and implementation of the MSLED, as well as the results of tests and initial deployments in Antarctica.

Scientific Challenges and Present Capabilities in Underwater Robotic Vehicle Design and Navigation for Oceanographic Exploration Under-Ice

“…SCINI has utilized LBL, SBL, and most recently a USBL navigation system [136] during a 2012-2015 field campaign surveying biomass at distinct trophic levels in the McMurdo Sound. Behar et al [137] discuss the design, testing, and deployments of the Micro Subglacial Exploration Device (MSLED) ROV. Weighing just under 2.9 kg, MSLED was designed to provide visual survey and horizontal CTD measurement capability in Subglacial Lake Whillans (SLW), Antarctica.…”

Enabling clean access into Subglacial Lake Whillans: development and use of the WISSARD hot water drill system

“…Following recovery of the water sampler, (5) the main hose and drill head were re-deployed into the borehole to melt the final 100 m of ice and attempt breakthrough into the lake, which seemed to be indicated by changes in the load cell and pressure sensor, which led to a decision to recover the drill hose to the surface. Then, (6) the micro subglacial lake exploration device (MSLED) 'mothership' and remotely operated vehicle (ROV) [56] was deployed into the borehole to provide real-time visual observations which indicated a deviation (bifurcation) at 690 m, potentially caused by a misalignment of the surface infrastructure (i.e. movement of the crescent assembly that guides the drill hose into the hole) prior to the redeployment of the main hose.…”

“…These observations and measurements helped to constrain the downhole uncertainties during hot water drilling into SLW, but real-time data are preferred, when possible. The use of MSLED provided some additional capability, but the low-weight vehicle had difficulty penetrating surface ice layers at the air/water interface in the borehole [56].…”

Probe technologies for clean sampling and measurement of subglacial lakes

“…(i) the camera-enabled micro-submersible Micro-Subglacial Lake Exploration Device (MSLED) [10]; (ii) a conductivity, temperature and depth (CTD) probe with integrated oxygen sensor (Seabird Electronics, USA), LISST deep particle analyser (Sequoia Scientific, USA), transmissometer (CStar, Wetlabs, USA) and Doppler current meter (Aquadopp, Nortek, Norway); (iii) CO 2 and CH 4 analysers (Contros GmbH, Germany); (iv) wet chemical analysers for NH 4 , NO 3 , Si, PO 4 (Envirotech, USA); (v) an integrated probe bottom section including an altimeter, down-and side-looking cameras and lights, fluorometer (FLNTU, Wetlabs), EM current meter (Contros GmbH) and altimeter (Tritech, UK); (vi) water sampler (Envirotech); (vii) a water sample pump (distributing to other elements); (viii) a lifting and telemetry stage;…”

“…The probes and instrumentation proposed for the direct measurement and sampling of Subglacial Lake Whillans (SLW) [9,10] include multiple packages designed to be deployed in succession down a shorter hot-water drilled borehole (800.4 ± 0.8 m [5] versus 3750 m [8] for SLV and 3155 ± 10 m for SLE [2]) which would remain open, with reaming, for approximately 8 days [9]. The instruments planned to be deployed [9,11,12] include:…”