Key Milestones for Today’s Launch

The Landsat 9 satellite, a joint NASA/U.S. Geological Survey mission that will continue the legacy of monitoring Earth’s land and coastal regions, is scheduled for liftoff today from Vandenberg Space Force Base in California at 11:12 a.m. PDT (2:12 p.m. EDT).
The Landsat 9 satellite, a joint NASA/U.S. Geological Survey mission that will continue the legacy of monitoring Earth’s land and coastal regions, is scheduled for liftoff today from Vandenberg Space Force Base in California at 11:12 a.m. PDT (2:12 p.m. EDT). Photo credit: NASA/Kim Shiflett

The Landsat 9 observatory will launch on a United Launch Alliance Atlas V 401 rocket from Space Launch Complex-3 at Vandenberg Space Force Base in California at 11:12 a.m. PDT (2:12 p.m. EDT).

Here’s a look at some of today’s upcoming countdown and ascent milestones. All times are approximate:

COUNTDOWN
Hr/Min/Sec      Event
– 00:16:00       Initiate fuel fill sequence
– 00:05:00       Fuel fill sequence is complete; water deluge system actuation pressure adjustment is performed; Atlas L02 at flight level; Centaur L02 at Flight level; Centaur LH2 at flight level
– 00:04:00       NAM and NLM final launch polls – go to continue countdown; spacecraft transfers to internal power
– 00:04:00       Hazardous gas monitoring is complete; automatic computer sequencer takes control for all critical events through liftoff; Atlas first stage LO2 replenishment is secured, allowing the tank to be pressurized for flight
– 00:03:00       Atlas tanks reach flight pressure
– 00:02:00       Atlas first stage and Centaur second stage switch to internal power; L02 and LH2 topping for Centaur will stop in 10 seconds
– 00:01:30       Launch control system is enabled
– 00:00:00      Ignition and liftoff of the Atlas V 

The United Launch Alliance Atlas V 401 rocket with NASA’s Landsat 9 satellite is secured on the launch pad at Space Launch Complex 3 (SLC-3) at Vandenberg Space Force Base in California, on Sept. 27, 2021.
The United Launch Alliance Atlas V 401 rocket with NASA’s Landsat 9 satellite is secured on the launch pad at Space Launch Complex-3 at Vandenberg Space Force Base in California, on Sept. 27, 2021. Photo credit: NASA/Kim Shiflett

LAUNCH AND SPACECRAFT DEPLOYMENT
Hr/Min/Sec    Event
00:01:27           Max Q (moment of peak mechanical stress on the rocket)
00:04:02          Atlas booster engine cutoff (BECO)
00:04:08          Atlas Centaur separation
00:04:18           Centaur first main engine start (MES-1)
00:04:26          Payload fairing jettison
00:16:30           Centaur first main engine cutoff (MECO-1)
01:20:40           Landsat 9 separation
01:50:43           Centaur second main engine start (MES-2)
01:50:53           Centaur second main engine cutoff (MECO-2)
02:10:53           Centaur third main engine start (MES-3)
02:11:03           Centaur third main engine cutoff (MECO-3)
02:14:05           Begin CubeSat Deployment
02:19:28           End CubeSat Deployment
02:57:44          Centaur fourth main engine start (MES-4)
02:58:09          Centaur fourth main engine cutoff (MECO-4)
03:19:56           End of mission

Tune in to NASA Television, the NASA app, or the agency’s website, or follow along here on the mission blog for a look at all of today’s major milestones.