Washington, June 30 : NASA is taking steps towards building Space Launch System (SLS) solid rocket boosters to support as many as six additional flights, for a total of up to nine Artemis missions. The US space agency on Monday said it will provide initial funding and authorisation to aerospace and defence technology company Northrop Grumman to order long-lead items to support building the twin boosters for the next six SLS flights. Under this letter contract, with a potential value of $49.5 million, Northrop Grumman will be able to make purchases as the details of the full contract are finalised within the next year. Northrop Grumman is the current lead contractor for the solid rocket boosters that will launch the first three Artemis missions, including the mission that will land the first woman and next man on the Moon in 2024. "This initial step ensures that NASA can build the boosters needed for future Space Launch System rockets that will be needed for the Artemis missions to explore the Moon," said John Honeycutt, SLS Program Manager at NASA's Marshall Space Flight Center in Huntsville, Alabama. "The letter contract allows us to buy long-lead materials in time for manufacturing boosters for the fourth flight." The twin solid rocket boosters, which are mounted on the side of the SLS core stage, will produce more than 75 per cent percent of the thrust for each SLS launch. The boosters were based on the design of the space shuttle solid rocket boosters but include a fifth segment to produce the extra power needed to send the larger SLS rocket to space. "We're ready to process and stack the boosters for the Artemis I mission, and we are making great progress producing boosters for the Artemis II and III missions," said Bruce Tiller, Manager of the SLS Boosters office at Marshall. "NASA is committed to establishing a sustainable presence at the Moon, and this action enables NASA to have boosters ready when needed for future missions." The Artemis programme is part of America's broader Moon to Mars exploration approach, in which astronauts will explore the Moon and experience gained there to enable humanity's next giant leap, sending humans to Mars. /IANS