The severe ice and snow that shut all telescopes at the Observatorio del Roque de Los Muchachos (ORM) for the first two weeks in February is slowly clearing, after temperatures finally rose above freezing on the 11th.
However, solid ice up to 50cm thick is packed in the enclosure mechanisms on the north-west side of the LT, out of sight of the exterior webcam. The ambient temperature is only just above freezing, and that, coupled with the lack of sunlight on that side of the building, means the ice is melting only very slowly. Removing the ice using antifreeze, salt or other chemicals is forbidden as the ORM is in a national park, and the salt especially would cause corrosion. Blasting the ice with a hot air blower would be very expensive for a start: we would need a huge device to deal with the amount of ice we need to melt, and we'd also run the very real risk of burning the hydraulic pipes and other mechanisms as the ice disappeared. Trying to chip the ice off also risks damaging the components underneath. So we are just having to wait for ambient conditions to remove the ice, and Winter is not yet over.
Update Fri 23rd Feb: The next bout of bad weather hit a little earlier than forecast; snow and ice now cover the roads at the mountaintop. The ORM have officially closed the roads leading to the telescopes, so engineering and maintenance support contractor Dirk Raback was not able to get to site today. More ice and sub-zero temperatures are expected over the weekend, which will no doubt deposit more ice on what we already have. Dirk will attempt to get to the LT again on Monday, but nevertheless we expect to be off-sky until Wednesday 28th February at the earliest.
The images on this page were taken by Dirk after he was first able to get to site on Monday 12th. They show the amount of ice still remaining on the enclosure, and the unusual shapes some of the ice formations took during the ice storm. The latest images are shown here, but see our Flickr "Telescope and Site" album for all of Dirk's recent ice images.