German space firm delays second rocket test flight for a fourth time

German rocket start-up Isar Aerospace has postponed the second test flight of its Spectrum rocket for a fourth time due to a technical problem, the company said on Monday.

The latest delay was caused by a malfunction in the rocket's fluid systems, according to a statement on the company's website. No further details were provided.

Fluid systems control the storage and flow of liquid propellants to a rocket's engines.

The second test flight had originally been planned for early this year, but launch preparations were previously halted in January, March and April. 

The first attempt was aborted because of a technical issue, while the second was delayed after a Norwegian fishing vessel failed to clear the safety zone around the launch site in time. The third and fourth attempts were called off because of technical problems.

Isar Aerospace's Spectrum rocket is designed to carry civilian and military satellites into low-Earth orbit once it enters commercial service. The company, based near Munich, aims to produce 40 rockets annually.

Despite the vehicle not yet being operational, Isar Aerospace says it is already booked through 2028 with contracts worth several hundred million dollars.

The start-up's importance to Germany's ambitions in the space sector was highlighted in March when Chancellor Friedrich Merz visited the Andøya launch site alongside Norwegian Prime Minister Jonas Gahr Støre.

Europe remains heavily reliant on foreign launch providers to send satellites into space. Most European satellites have for years been launched by US company SpaceX.