A 2011 file photo of an Ariane 5 rocket rolling out to the launch pad. Credit: Arianespace

PARIS — The Arianespace launch consortium has canceled today’s planned launch of a heavy-lift Ariane 5 rocket due to an unexplained issue on the rocket that appears to be unrelated to the previous issue that scrubbed the planned April 15 launch.

In a statement, Arianespace said “an anomaly occurred on the conditioning equipment of the launcher,” which on April 23 had been moved to the launch pad from the final-assembly building at the Guiana Space Center on the northeast coast of South America.

The incident occurred, or was discovered, late in the evening April 23 French Guiana time.

Logos for the launch's two passengers —Thor 7 and Sicral 2 — are installed on the Ariane 5 payload fairing. Credit: Arianespace
Logos for the launch’s two passengers —Thor 7 and Sicral 2 — are installed on the Ariane 5 payload fairing. Credit: Arianespace
Logos for the launch’s two passengers —Thor 7 and Sicral 2 — are installed on the Ariane 5 payload fairing. Credit: Arianespace

The launch, which will be the first of what Evry, France-based Arianespace had hoped could be as many as seven Ariane 5 missions conducted this year, will carry the commercial Thor 7 telecommunications satellite for Norway’s Telenor Satellite Broadcasting, which is in the Ariane 5 rocket’s upper berth.

Occupying the lower berth is the Sicral 2 military communications satellite, which carries separate payloads for the French and Italian defense forces.

An Arianespace official said the issue was a helium-flush pipe located between the rocket’s upper stage and the main cryogenic stage that disconnected during initial pressurization the evening of April 23 after the rocket had been moved to the launch pad.

The helium flush prevents ice buildup. The official said the pipe became disconnected during the pressurization, and that it will be replaced. The official said there remained a possibility that the procedure could be completed in time to move the rocket back to the launch pad and attempt an April 25 launch.

Peter B. de Selding was the Paris bureau chief for SpaceNews.