On Aug. 24, technicians at NASA’s Kennedy Space Center in Florida began installing the four RS‑25 engines in the core stage of the agency’s Space Launch System (SLS) rocket that will carry the Artemis III crew into low Earth orbit in 2027.

Each RS‑25 engine has a unique serial number that records its detailed flight history. The four engines assigned to Artemis III — E2054, E2057, E2048, and E2052 — previously powered multiple space shuttle missions. Engine 2048 helped launch NASA astronaut Randy Bresnik’s earlier mission aboard space shuttle Atlantis during STS‑129. It also flew on Space Shuttle Discovery during STS‑95 in 1998, the mission that returned 77-year‑old space pioneer U.S. Sen. John Glenn to orbit, making him the oldest person to fly in space at that time.