Amazon billionaire Jeff Bezos is showing off a picture of his Blue Origin space venture’s BE-4 rocket engine going full blast during a hot-fire test in Texas.

“BE-4 continues to rack up time on the test stand,” Bezos said in an Instagram post accompanied by a picture of today’s full-power engine test.

Getting the BE-4 into operation is crucial to Blue Origin’s space ambitions.

The rocket engine, which runs on liquefied natural gas and packs 550,000 pounds of thrust at liftoff, is destined for use on Blue Origin’s orbital-class New Glenn rocket. It’s also supposed to power United Launch Alliance’s next-generation, semi-reusable Vulcan rocket.

Both those rockets are currently scheduled to have their maiden launches in 2021.

Bezos’ company tends to play its cards closer to the vest than rival billionaire Elon Musk’s SpaceX, which has been letting its fans pass along real-time streaming video of its Raptor rocket engine test firings and Starship hops in South Texas over the past few months.

Blue Origin has been testing BE-4 engine components at its West Texas proving ground for more than two years, and the course has not always run smooth. In May 2017, for instance, Bezos acknowledged that a test of the engine’s powerpack went awry, resulting in the loss of hardware.

The fact that he’s sharing a picture of the full-power firing on a summery Friday night suggests that the test program is on track. But it also suggests there are more test firings to go.

Bezos has said more than once that he’s spending $1 billion or more on Blue Origin annually. Just in the past few days, Bezos sold off more than $1.8 billion of Amazon stock, and it’s a sure bet that some of that cash is going toward the BE-4.

When the BE-4 gets an honest-to-goodness thumbs-up, that’ll clear the way for engine production to shift from Blue Origin’s headquarters in Kent, Wash., to a 200,000-square-foot factory that’s currently under construction in Huntsville, Ala. That, in turn, will set the stage for New Glenn rocket assembly to move ahead at Blue Origin’s 750,000-square-foot facility in Florida.

Bottom line? Keep an eye on Bezos’ Instagram account and Blue Origin’s Twitter account for word that the BE-4 has passed its final test.