The heart of NASA’s second Space Launch System rocket arrived at Florida’s Kennedy Space Center this week, and NASA officials plan to start assembling the massive rocket within the next few months for a mission to orbit the moon with a team of four astronauts late next year.
The Artemis II mission, officially scheduled for September 2025, will be humanity’s first journey to the lunar vicinity since the final Apollo moon landing mission in 1972. NASA astronauts Reed Wiseman, Victor Glover and Christina Koch, along with Canadian mission specialist Jeremy Hansen, will leave Earth aboard an SLS rocket, then orbit the far side of the moon before returning aboard NASA’s Orion spacecraft.
“The core is the backbone of the SLS and it’s the backbone of the Artemis program,” said Matthew Ramsey, NASA’s Artemis II mission manager. “We’ve been eagerly awaiting the arrival of the core because we needed the core stage for all the integration testing and checkouts that we need to do. The core stage houses the avionics that power the entire system. The boosters are important, but the core is the backbone of the Artemis program. So today is a big day.”
The core stage is NASA’s Pegasus The Boeing barge arrived at the Kennedy Space Center early Wednesday after a week-long voyage from New Orleans, where the rocket is being built under contract to NASA.
Ramsey told ARS that ground teams will begin stacking the two powerful solid rocket boosters on NASA’s mobile launch pad in September. Each booster, supplied by Northrop Grumman, is made of five segments and a nose cone that are pre-packed with solid fuel. All of the SLS booster parts are at Kennedy Space Center and ready to be stacked, Ramsey said.
The SLS upper stage, built by United Launch Alliance, is also at the Florida launch site. Currently, the core stage is at Kennedy. In August or September, NASA plans to deliver the remaining two elements of the SLS rocket to Florida: the adapter structure that connects the core stage to the upper stage and the upper stage to the Orion spacecraft.
Large cranes inside the enormous Vehicle Assembly Building (VAB) will hoist each segment of the SLS booster onto the launch pad. Once the boosters are fully stacked, ground teams will lift the 212-foot (65-meter) core stage vertically up a walkway through the center of the VAB. The crane will then lower the core stage between the boosters, which Ramsey says could happen as soon as December.
Next comes the launch vehicle’s stage adapter, the upper stage, the Orion stage adapter, and finally the Orion spacecraft itself.
Towards operation
NASA’s inspector general reported in 2022 that each of the agency’s first four Artemis missions will cost $4.1 billion. Last year’s Government Accountability Office reportsuggests that the expendable SLS core stage accounts for at least a quarter of the cost of each Artemis flight.
Artemis II’s core stage will be powered by four hydrogen-fueled RS-25 engines manufactured by Aerojet Rocketdyne. Two of Artemis II’s reusable engines have flown on the Space Shuttle; the other two RS-25s were built during the Shuttle era but never flew. After each SLS launch, the core stage and its engines will float in the Atlantic Ocean.
Steve Wofford, who manages the SLS program’s stage office at NASA’s Marshall Space Flight Center, told Ars that there are “no major configuration differences” between the core stages of Artemis I and Artemis II. The only minor difference concerns the instruments NASA intended to put on Artemis I to measure pressure, acceleration, vibration, temperature, and other parameters during the Space Launch System’s first flight.
“We’re still doing the flight observations that we did on Artemis I, and we haven’t had any catastrophic issues,” Wofford said. “We really loaded up on Artemis I, the first installment, the test flight, and this is a great opportunity to learn as much as we can about the vehicle and the flight regime and get all the models locked down. … As we progress, we’ll have fewer and fewer of those, so in Core Stage 2 we’ll have fewer developmental flight instruments than we did in Core Stage 1, and even fewer in Core Stage 3.”
