This unaltered story was originally published by U.S. NASA Space Agency.

This unaltered story was originally published by U.S. NASA Space Agency.
URL: https://www.nasa.gov
Content is in public domain.

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Key Milestones for Today’s Launch – Landsat 9

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Date: 2021-09-27 00:00:00

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

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.

[END]

[1] Url: https://blogs.nasa.gov/landsat9/2021/09/27/key-milestones-for-todays-launch/

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