Creating a 3D map of the world’s largest volcanic cave to aid future space missions

Despite being hundreds of thousands of kilometres apart, the island of Lanzarote and the Moon share remarkable similarities. The Spanish island, belonging to the Canary archipelago in the Atlantic, is home to the world’s largest volcanic cave and exceptional scenery that resembles the lunar landscape. So much in fact that the island has been chosen as a location for astronaut training ahead of space missions. More recently, Lanzarote’s Corona lava tube has helped prepare teams at the European Space Agency to explore and study caves of similar characteristics observed on the Moon and on planets like Mars.

由于最新的地理空间技术进步和创新，2017年由Virtual Geographic Agency的Tommaso Santagata领导的几项现场调查维亚, deploying3D Terrestrial Laser Scanning（TLS）和Mobile Mapping solutions, resulting in the first ever 3D replica of the largest lava tube on Earth.

Exploring the depths of the Corona lava tube

Located in the north of Lanzarote, the Corona lava tube extends over 8.5 kilometres and is made up of both dry and submerged passages, with some sections more than 25 metres wide. Although the first explorations and initial mapping began in the seventies, its real extension was practically unknown until the early sixties when the first topographic survey was carried out. This latest and most ambitious 3D scanning project, commissioned by the local government, Cabildo de Lanzarote, also implemented the latest mobile mapping technology, which is part of the European Space Agency’s training course PANGAEA-X. This training allows them to test new instruments and technologies that will be used in future space missions.

In order to successfully execute this project, various field surveys were completed over the course of a year deploying a variety of Leica Geosystems solutions, including theLeica HDS7000,Leica ScanStation P40和Leica BLK360laser scanners, as well as theLeica Pegasus:Backpackmobile mapping solution. The result is the largest 3D replica of a lava tube on the planet with 5.7 kilometers of cave passages mapped.

使用最新的激光扫描技术捕获所有细节

Three individual surveys and over 440 scans were completed to map the lava tube system, composed of different sections connected to each other through external collapses. These collapses were used to geo-reference the laser scanning surveys performed inside the cave on the external surface. This was made possible with Global Navigation Satellite System (GNSS) measurements, Light Detection and Ranging (LiDAR) data from the Spanish Geological Service, and through photogrammetry data obtained with unmanned aerial vehicle (UAV) flights along the cave path.

More specifically, 800 metres of the above sea level passages were mapped using the HDS7000 and an estimated five kilometres using a ScanStation P40. In addition, the BLK360 imaging laser scanner was deployed to scan an upper level of around 300 metres during the PANGAEA-X expedition.

Leica Pegasus的准确性和机动性提高：背包

为了生成更详细的3D地图，使用Pegasus：背包移动映射解决方案进行了调查。旨在在地上和地下环境中捕获3D数据，其中图像和点云由五个摄像机和两个激光探测器收集。它的轻量级和人体工程学结构使团队能够舒适地浏览困难的地形并立即可视化手持板计算机上的数据。

“由于t的错综复杂和地下自然he lava tube system, the Pegasus:Backpack was deployed to acquire fused SLAM data — starting and ending in outdoor environments with GNSS data, but largely exploring the cave without satellite coverage,” explains Tommaso Santagata, Co-Founder of Virtual Geographic Agency Vigea 3D and an expert on Lanzarote’s volcanic cave system. As the lengthiest part of the mission was carried out without any GNSS information, the second phase of the data processing was to reinforce the calculation of the path recorded using a SLAM algorithm and the information obtained by the LiDAR mounted on the Pegasus:Backpack.

Processing the data and creating the final 3D map

“Having gathered large amounts of data — 400 GB corresponding to the raw laser scanning data alone — theLeica Cyclone然后部署了3D点云处理办公软件以对齐扫描并处理洞穴的统一点云。” Santagata说。“一旦3D地图在单点云中可用，就会生成几个输出作为具有熔岩管的计划和部分的地形图。”此外，随后将数据用于与地球上其他熔岩管进行比较，目的是在月球和火星上研究类似的特征 - 此操作是使用该操作的Autodesk AutoCAD2017年软件。

除了对未来太空任务的科学目的和培训外，数据还用于生产多媒体和互动内容，例如视频动画，虚拟现实和桌面应用程序，显示了更广泛的公众是Corona熔岩管系统中鲜为人知的部分。只有有限的部分向Cueva de Los Verdes和Jameos del Agua开放。此外，该项目的结果是在Cabildo de Lanzarote在2019年组织的旅游洞穴管理的活动中提出的，该洞穴于2019年安装了一个虚拟现实摊位，向公众展示了洞穴。

Latest expedition update: Supporting the search for “stone-eating” bacteria

In spring 2021, Santagata returned to Lanzarote to support a microbiology research project. The Tubolan project, led by Ana Miller, geomicrobiologist at the Institute of Natural Resources and Agrobiology of Seville (CSIC), was set up to study the microbial organisms living in the Lanzarote lava tube systems. The team’s findings will help those searching for life on the Moon and Mars, which also have lava systems. Although the conditions are different to those on earth, the Martian and lunar cave systems could theoretically also support chemolithoautotrophic microorganisms that survive and grow by using and transforming minerals. In the framework of the Tubolan project, Santagata used a Leica BLK360 to make scans and 360 degree videos – contributing to the study of caves’ formation and uncovering more of the caves’ geography than ever before. The amazing video footage taken can be watched onVIGEA’s YouTube channel.

Further reading:
Sauro F.，Pozzobon R.，Santagata T.，Tomasi I.，Tonello M.，Martínez-FríasJ。，Smets L.M.，GómezG.D。，Massironi M.（2019）Volcanic Caves of Lanzarote: A Natural Laboratory for Understanding Volcano-Speleogenetic Processes and Planetary Caves.In Lanzarote and Chinijo Islands Geopark: From Earth to Space (pp. 125-142). Springer, Cham.

SAURO F, POZZOBON R。DE BERNARDINI MASSIRONI MS P., SANTAGATA T., DE WAELE J. (2020)地球，月亮和火星上的熔岩管：比较行星学揭示其大小和形态的评论. Earth Science Reviews 103288.