The United Launch Alliance (ULA) is launching the classified USSF-51 mission, for the United States Space Force (USSF). The mission was initially planned to launch on ULAs Vulcan rocket, but the company requested a move to the Atlas V rocket. The Atlas for this mission is in the 551 configuration, meaning 5 SRBs (Solid Rocket Booster), bigger fairing, and a single upper stage engine.
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TechTranscript
00:009, 8, 7, 6, 5, 4, 3, 2, 1.
00:08We have ignition and liftoff of the United Launch Alliance Atlas V rocket carrying USSF-51
00:17for the United States Space Force on ULA's 100th National Security Mission.
00:23Hydraulics look good.
00:26We are throttling down in preparation for max Q.
00:36Everything looking good.
00:37P is at close of control.
00:42Animal program did complete on time.
00:47Mach 1.
00:48Vehicle is now supersonic.
00:50Engine continues to operate normally.
00:52SRB is burning normally.
00:53Everything looking good.
00:55Now we're hearing the voice of Rob Gannon providing launch vehicle ascent data.
01:01Max Q. We're throttling up post max Q as expected.
01:06Everything looking good.
01:07Following expected profile.
01:12SRB is burning normally.
01:14RD-180 operating expected throttle level.
01:18Everything looking good.
01:27Body weights look good.
01:29We now throttle down in preparation for SRB burnout.
01:38We are now 50% of our liftoff weight.
01:41SRB is rolling off.
01:45And we have SRB burnout.
01:47SRB jettison.
01:55SRB jet.
01:58All five SRBs successfully jettisoned the vehicle.
02:00RD-180 is throttled up and operating normally.
02:02Everything looking good.
02:07We're now 34 miles in altitude, 36 miles downrange, traveling at 4,200 miles per hour.
02:16Quick review of our range track.
02:20Vehicle is proceeding right down the center of the range track.
02:22Everything looking good.
02:30And we did enable closed-loop steering a few seconds ago.
02:33Everything looks good there.
02:38Next event we're looking for is throttling down to a constant 2.5 G limit for payload fairing jettison.
02:49And we've begun to throttle down, holding a constant 2.5 Gs in preparation for fairing jet.
03:00And we fired the power valve, activating the reaction control system on the second stage.
03:06And we just passed through the von Karman line.
03:0825% of liftoff weight.
03:16Ten seconds to fairing jet.
03:25We have fairing jettison.
03:31And sealed-off deck jettison.
03:37And we've throttled up the RD-180.
03:46This is Atlas Mission Control at T-plus 3 minutes and 38 seconds.
03:51We just heard flight commentator Rob Gannon confirm the successful completion of the early phase of today's flight,
03:57and all systems continue to operate nominally.
04:00At this time, we're going to end our live coverage.