Fourth SDA Tranche 1 Mission Set To Launch From Vandenberg SFB Early Monday Morning
VANDENBERG SPACE FORCE BASE, Calif. (KEYT) – A Falcon 9 launch of the Space Development Agency's fourth Tranche 1 mission is scheduled to launch early Monday morning.
Liftoff on the mission is currently scheduled for 1:17 a.m. on Monday, Oct. 5, 2026, and a backup window has been designated for the following day, Tuesday, Oct. 6 at 1:08 a.m. Pacific Time.
This will be the fourth of nine Tranche 1 mission to bring a proliferated constellation of satellites in low-Earth orbit that facilitate global military tactical communications and alerts for the American military explained the Space Development Agency.
According to SpaceX, this mission is to deliver 21 data transport satellites as part of the far larger observational fleet of satellites.
Prior launches of the Tranche 1 network were conducted in September 2025, October 2025, and July of this year from Vandenberg Space Force Base.
The Department of Defense already uses about ten missile defense satellites operating in a geosynchronous orbit at an altitude of about 22,000 miles, but the far smaller Tranche mission satellites will operate at a lower altitude of approximately 600 miles above the Earth.
"As threats to space expand, we can no longer rely on a strategy of putting most of our capabilities into these few large exquisite satellite systems," explained Kari Bingen, Director of the Aerospace Security Project at the nonprofit Center for Strategic and International Studies. "Now the DOD [Department of Defense] is taking the approach of building many systems on shorter timelines."
Eventually, the Space Development Agency intends to field anywhere from 300 to over 500 satellites of various sizes with an expectation that when fully operational, 95 percent of the Earth would have at least two satellites in view and 99 percent of surface locations around the globe would have at least one satellite.
A live webcast of Monday's launch will begin about ten minutes before liftoff. You can tune in to watch here or on SpaceX's X/Twitter account.
Following first-stage separation, the reusable booster assigned to this mission will return to Earth and land at Landing Zone 4 on Vandenberg Space Force Base approximately eight minutes after liftoff.
A depiction of that launch sequence is shown in the image below.
There is the potential for sonic booms associated with the launch to be heard across the local region, but how far the sound travels will depend on weather and other conditions at launch time.
This will be the sixth flight for the Falcon 9 on this mission. The same booster previously launched the following missions:NROL-179, SDA-T1TL-E, and three Starlink launches.
