Week in Space Data, every Friday.
Remind me about this launch
No firm date yet. We'll email when it gets one. A day before, an hour before, if the launch time moves, and when it flies. No account.
The webcast for Vulcan · NROL-73 appears here once the provider posts it.
The broad sequence of an orbital launch. Details and times differ by rocket and mission; this is a guide, not live tracking.
In the last part of the count the rocket is fuelled, systems switch to internal power and the launch team is polled for a go.
The first-stage engines ignite and the rocket leaves the pad.
The moment of maximum aerodynamic pressure on the rocket during ascent.
The spent first stage separates and the upper stage takes over. Some rockets also drop side boosters earlier in the climb.
The upper stage burns to reach the planned orbit, sometimes in more than one burn with a coast in between.
The payload separates from the upper stage. On a crewed flight the capsule separates and flies on under its own power.
Chat opens two hours before liftoff once the launch time is set.
Telemetry and trajectory data shown is simulated for demonstration purposes. Real telemetry data would require integration with launch provider APIs.
Every entry is a change we recorded, not a forecast. Our sync checks Launch Library 2 every 15 minutes, so a time is when we saw the change and can trail the real moment. The liftoff time is the one the launch record states.
Nothing has changed on this launch since we started recording it. Status changes, date moves and the liftoff will appear here as they are recorded.
Vulcan Centaur (United Launch Alliance)
Vulcan Centaur uses two BE-4 engines on its first stage and a Centaur V upper stage with RL10 hydrogen engines. Solid rocket boosters strap on for heavier missions; the number is in the rocket’s configuration.
Source: ULA: Vulcan Centaur, checked 2026-09-27The provider's page for this flight
Checking for a discussion…
Part of a tracked program. See it on the National Security Space Launch (NSSL) Phase 2 and Phase 3 tracker, with the program's contracts, satellites and launch slips.