As of 2020, three SLS versions are planned: Block 1, Block 1B, and Block 2.
Each will use the same core stage with four main engines, but Block 1B will feature the Exploration Upper Stage (EUS), and Block 2 will combine the EUS with upgraded boosters.

In mid-November 2014, construction of the first core stage hardware began using a new welding system in the South Vertical Assembly Building at NASA's Michoud Assembly Facility.
Between 2015 and 2017, NASA test fired RS-25 engines in preparation for use on SLS.

As of late 2015, the SLS program was stated to have a 70% confidence level for the first crewed Orion flight by 2023, and as of 2020, NASA is continuing to project 2023.
While the SLS/Orion combination can do a lunar flyby mission, as is planned for Artemis 2 in 2023, the SLS/Orion has insufficient capacity to get the heavy Orion capsule into low lunar orbit and return to Earth.

Confidence article builds for the core stage began on 5 January 2016 and were expected to be completed in late January of that year.
Once completed the test articles were to be sent to ensure structural integrity at Marshall Spaceflight Center.
A structural test article of the ICPS was delivered in 2015.
the core stage for Artemis 1 completed assembly in November 2019.

The intended uncrewed first flight of SLS has slipped multiple times: originally from October 2016 to October 2017, to November 2018, then to 2019, then to June 2020, then to April 2021, and most recently to November 2021.

The first core stage left Michoud for comprehensive testing at Stennis in January 2020.
The static firing test program at Stennis, known as the Green Run, will operate all the core stage systems simultaneously for the first time.
As of 2020, three SLS versions are planned: Block 1, Block 1B, and Block 2. Each will use the same core stage with four main engines, but Block 1B will feature the Exploration Upper Stage (EUS), and Block 2 will combine the EUS with upgraded boosters.
In mid-November 2014, construction of the first core stage hardware began using a new welding system in the South Vertical Assembly Building at NASA's Michoud Assembly Facility. Between 2015 and 2017, NASA test fired RS-25 engines in preparation for use on SLS.
As of late 2015, the SLS program was stated to have a 70% confidence level for the first crewed Orion flight by 2023, and as of 2020, NASA is continuing to project 2023. While the SLS/Orion combination can do a lunar flyby mission, as is planned for Artemis 2 in 2023, the SLS/Orion has insufficient capacity to get the heavy Orion capsule into low lunar orbit and return to Earth.
Confidence article builds for the core stage began on 5 January 2016 and were expected to be completed in late January of that year. Once completed the test articles were to be sent to ensure structural integrity at Marshall Spaceflight Center. A structural test article of the ICPS was delivered in 2015. the core stage for Artemis 1 completed assembly in November 2019.
The intended uncrewed first flight of SLS has slipped multiple times: originally from October 2016 to October 2017, to November 2018, then to 2019, then to June 2020, then to April 2021, and most recently to November 2021.
The first core stage left Michoud for comprehensive testing at Stennis in January 2020. The static firing test program at Stennis, known as the Green Run, will operate all the core stage systems simultaneously for the first time.
Space Launch System