A Falcon 9 launch

One launch, counted from the moment of liftoff

Relative time counts from a moment instead of a calendar date. Here that moment is liftoff, T−0, and every item reads as a distance from it: “−38 min” is the launch director’s go for propellant load, “+2 min 13 s” is main engine cutoff. This timeline has a floating epoch named “Liftoff”, so it shows no real date at all. Give it an anchored epoch, 23 July 2025 at about 18:13 UTC, and the same items read as clock times.

The mission is TRACERS: a Falcon 9 launched NASA’s TRACERS satellites on 23 July 2025 at 11:13 a.m. PT from Space Launch Complex 4 East at Vandenberg Space Force Base, California, together with five rideshare payloads. Every item cites SpaceX’s own page for that mission. The countdown is SpaceX’s standard Falcon 9 payload countdown, as that page shows it; everything after liftoff is this mission’s own sequence, which SpaceX marks “All Times Approximate”. Those times differ from flight to flight, so they are never a blend.

What to try

• Follow the three layers: the countdown and the first-stage ascent, the booster’s way back to its landing zone, and the second stage with its payloads.

• Zoom in on the last minute of the countdown, where steps sit seconds apart, then out to the whole 2 hours 24 minutes.

• Filter by tag: countdown, ascent, booster, second stage or payload.

• Relative time also counts weeks: see Pregnancy week by week.