Work begins on rocket engines for SLS flights a decade from now
One of the primary criticisms of NASA’s Space Launch System is that the program was created to save jobs at key agency contractors that otherwise would have been lost following the end of the space shuttle program. The large, new rocket includes several heritage components from the shuttle, including its main engines.
When the space shuttle program ended in 2011, NASA had 15 of the reusable main engines left over and has since built one more from spare parts. Because the expendable SLS rocket will use four engines in its core stage, this means NASA presently has enough for the first four flights of the SLS rocket.
NASA will therefore eventually need more engines for the SLS rocket—assuming the rocket flies more than a handful of flights— and so the agency awarded Aerojet Rocketdyne a $1.16 billion contract in 2016 to restart production of a modified version of the space shuttle main engine, known as the RS-25. In addition to this, the space agency placed an order for six “flight” engines, bringing the total value of the contract to $1.5 billion.