The White House’s proposed 2020 fiscal year budget seeks to shelve the development of an upgraded version of NASA’s Space Launch System (SLS). The shift in focus will likely result in several missions slated to be launched aboard the rocket shifted to commercial partners, including the construction of the agency’s lunar-orbit space station.

Released by the Office of Management and Budget on March 11, the proposed budget allocates $21.02 billion to NASA. Despite the amount being a 1.4-percent increase when compared to the 2019 estimate, it’s a $480 million cut on the amount actually allocated in the final 2019 fiscal year spending bill signed into law on February 15.

Changes to the SLS program where the most significant year on year. Funding for the development of the rocket in 2020 will account for $1.7 billion of NASA’s budget, down by $375 million from 2019. This has forced the development of the upgraded Block 1B variant of the rocket to be indefinitely shelved.

The Block 1B variant of the SLS would boost its performance by replacing the Interim Cryogenic Propulsion Stage (a variant of the second stage developed for the ULA Delta IV rocket) with the Exploration Upper Stage currently being developed by Boeing.

With the move away from the more powerful SLS variant, a number of missions slated to be launched aboard the Block 1B will be shifted to commercial rockets. The proposal specifically identifies the Europa Clipper mission which received $600 million for commercial launch services with a targeted launch date in 2023. The budget claims that this shift will free up over $700 million in funding that can be then be allocated to other programs.

In addition to shifts in the funding of the SLS program, the budget proposal also hinted that the rocket’s maiden flight would slip from the proposed 2020 launch date. Under a section detailing NASA’s proposed efforts to return to the moon, the budget reveals the first uncrewed test is now targeted to be launched in the “early 2020s”.





