The debut of Russia’s new light-class Angara rocket has been delayed for several weeks as engineers investigate a defect in the drainage valve of a liquid oxygen tank discovered during pre-launch checks. “An emergency shutdown occurred 79 seconds before the start of the launch,” Russian engine maker NPO Energomash said in a statement posted on its website. “The reason was a pressure drop of the oxidizer tank spherical balloon,” which the company said is not part of the Angara’s first stage RD-191.