The first test launch of NASA's new "Space Launch System" rocket was originally scheduled to debut in 2017, but after many delays and cost overruns it now seems unlikely that the rocket will launch before mid-2021.

Meanwhile, rapid advancements by private companies like SpaceX and Blue Origin offer the promise of heavy-lift rockets (Falcon Heavy and New Glenn) with capabilities only slightly less than the SLS for a vastly lower cost. The arrival of these new rockets in the face of ongoing SLS costs and delays could provide strong political pressure to cancel NASA's most expensive human spaceflight program, perhaps after only a handful of flights.

On the other hand, the SLS has strong political support at the moment, and it is already deeply interwoven into many aspects of NASA's future plans. In addition to the initial uncrewed and crewed test flights, SLS is currently scheduled to send the "Europa Clipper" robotic probe to Jupiter sometime around 2023, and several launches will be required if NASA is to fully assemble the "Lunar Gateway" space station as currently envisioned.

How will these forces play out? Will endless delays ensure that only a small number of SLS launches happen before 2030? Will the program be canceled before 2030, ending the SLS after just a handful of flights? Or will the SLS find plenty of work constructing the Lunar Gateway and perhaps launching other large payloads?

Question will resolve on January 1, 2030, or earlier if the SLS program is definitively canceled. Any distance lifted off the launchpad counts as a launch, regardless of whether the rocket explodes moments later.