BREMEN, Germany — A SpaceX bid to launch Germany’s optical intelligence, reconnaissance and surveillance satellites coupled with the Falcon 9 rocket’s increased flight rate — the key incredient for cost-effective rocket-stage reuse — has raised fresh questions about whether Europe’s launch sector can remain viable.

Recent signals include:

— The German Aerospace Center, DLR, conducted an analysis of Falcon 9 first-stage reuse and concluded that SpaceX could begin to realize significant cost savings with as few as 20-25 launches per year, lower than previous outside assessments . . .

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