This story was originally published by NASA and is unaltered.

(C) NASA
This story was originally published by NASA and is unaltered.
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NASA’s TRACERS Mission Launch Attempt Today [1]

['Elyna Niles-Carnes']

Date: 2025-07-23

NASA’s TRACERS Mission Launch Attempt Today

A SpaceX Falcon 9 rocket carrying NASA’s TRACERS (Tandem Reconnection and Cusp Electrodynamics Reconnaissance Satellites) mission stands vertical Tuesday, July 22, 2025, at Space Launch Complex 4 East at Vandenberg Space Force Base in California. SpaceX

A SpaceX Falcon 9 rocket with NASA’s TRACERS (Tandem Reconnection and Cusp Electrodynamics Reconnaissance Satellites) mission onboard has a second opportunity to launch the pair of satellites that will study space weather for the agency. The 57-minute launch window opens at 2:13 p.m. EDT (11:13 a.m. PDT) for today’s mission from Space Launch Complex 4 East at Vandenberg Space Force Base in California.

Yesterday’s launch attempt stood down due to Federal Aviation Administration airspace concerns, but the rocket and payloads remain in good health and poised for today’s attempt.

The TRACERS mission will study explosive events called magnetic reconnection that can hurl solar wind particles the Earth’s magnetosphere usually deflects into the atmosphere. The team designed the twin satellites to make 3,000 measurements of magnetic reconnections during their yearlong prime mission.

Riding along with TRACERS are three additional NASA-funded small satellites: Athena EPIC (Economical Payload Integration Cost), PExT (Polylingual Experimental Terminal), and REAL (Relativistic Electron Atmospheric Loss). Each will demonstrate innovative technologies and gather new scientific data in as they orbit Earth.

SpaceX will provide live coverage on its website and at @SpaceX on X, beginning about 15 minutes before liftoff.

Here’s a closer look at countdown and ascent milestones (all times are approximate):

Hr/Min/Sec Event

00:38:00 SpaceX Launch Director verifies go for propellant load

00:35:00 RP-1 (rocket grade kerosene) loading begins

00:35:00 1st stage LOX (liquid oxygen) loading begins

00:16:00 2nd stage LOX loading begins

00:07:00 Falcon 9 begins engine chill prior to launch

00:01:00 Command flight computer to begin final prelaunch checks

00:01:00 Propellant tank pressurization to flight pressure begins

00:00:45 SpaceX Launch Director verifies go for launch

00:00:03 Engine controller commands engine ignition sequence to start

Falcon 9 liftoff

00:01:12 Max Q (moment of peak mechanical stress on the rocket)

00:02:13 1st stage main engine cutoff (MECO)

00:02:17 1st and 2nd stages separate

00:02:21 Stage 1 flip

00:02:24 2nd stage engine starts (SES-1)

00:02:30 Boostback burn starts

00:02:56 Fairing separation

00:03:26 Boostback burn ends

00:06:04 1st stage entry burn begins

00:06:21 1st stage entry burn ends

00:07:12 1st stage landing burn begins

00:07:46 1st stage landing

00:08:02 2nd stage engine cutoff (SECO-1)

00:50:44 2nd stage engine starts (SES-2)

00:50:47 2nd stage engine cutoff (SECO-2)

00:54:30 Bard deploys (Host spacecraft for PExT)

00:54:50 REAL deploys

01:05:40 2nd stage engine starts (SES-3)

01:05:41 2nd stage engine cutoff (SECO-3)

01:30:07 2nd stage engine starts (SES-4)

01:30:08 2nd stage engine cutoff (SECO-4)

01:34:26 First TRACERS satellite deploys

01:40:41 Second TRACERS satellite deploys

01:44:46 Epic Athena deploys

01:45:06 LIDE deploys

01:45:26 Skykraft 4 deploys

For additional updates, follow @NASAKennedy on X and visit the TRACERS blog.

[END]
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[1] Url: https://www.nasa.gov/blogs/smallsatellites/2025/07/23/nasas-tracers-mission-launch-attempt-today/

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