STS-131 Launch Timeline

April 5, 2010 10:44 by scibuff

Update: See the mission details and more photos in my STS-131 Space Shuttle Discovery post.

The milestones of STS-131 Space Shuttle Discovery launch (reverse order):

~ 10:31:10 GMT @ T+09:45 – Nominal MECO, OMS-1 not required. With a direct insertion ascent, the main engines are burned slightly longer to achieve the desired apogee altitude, such that an OMS-1 maneuver (which would supply the additional thrust needed to reach orbit) is not required.

– 10:30:00 GMT @ T+08:35 – External Tank (ET) separation.


External Tank Separation - Credit: NASA TV

– 10:29:55 MT @ T+08:30 – Zero Thrust.

– 10:29:49 GMT @ T+08:24 – Main Engine Cut-off (MECO). Discovery has reach the planned orbit and is schedule to dock with the International Space Station on Flight Day 3 (April 7).

– 10:29:07 GMT @ T+07:42 – Negative Istres.

– 10:28:45 GMT @ T+07:20 – Negative Moron.

– 10:27:40 GMT @ T+06:15 – Press to MECO and Single Engine Zaragoza 104 – Discovery can now reach planned orbit in case of a single SSME failure and the Zaragoza TAL site on a single engine at 104.5% throttle.

– 10:27:26 GMT @ T+06:01 – Single Engine OPS-3 Zaragoza – Discovery could now reach the designated TAL site with a single engine at Full Power Level (FPL), i.e 109% throttle, should two of the SSME‘s fail (the OPS-3 software mode will be used for re-entry) – Prior to this point, the loss of two engines requires contingency abort procedures and OPS 6 software.

– 10:27:12 GMT @ T+05:47 – Roll to heads up.

– 10:26:36 GMT @ T+05:11 – Press to ATO select Zaragoza – Discovery could now reach a safe orbit (circular / 194.5 km) with two Space Shuttle Main Engines (SSME) throttled at Typical Mission Power Level (104.5%) in case of a single SSME failure. Should one of the engines fail the crew could execute the Abort To Orbit (ATO) maneuver (in case of TAL abort, the landing facility in Zaragoza would be used).

– 10:25:12 GMT @ T+03:47 – Negative Return – Discovery has used too much fuel and is traveling too fast (8 779 km/h), too high (96 km) and is too far (200 km) to return to the Shuttle Landing Facility (SLF) at the Kennedy Space Center (KSC) for a potential Return To Launch Site (RTLS) abort.

10:24:17 GMT @ T+02:52 – 2 engine Istres. Discovery can now reach the Transoceanic Abort Landing (TAL) site in Istres in the case of a single engine failure.

10:24:06 GMT @ T+02:41 – 2 engine Zaragoza. Discovery can now reach the TAL site in Zaragoza in the case of a single engine failure.

10:24:00 GMT @ T+02:35 – 2 engine Moron. Discovery can now reach the TAL site in Moron in the case of a single engine failure.

– 10:23:40 GMT @ T+02:15 – Orbital Maneuvering System (OMS) assist (1m 44 seconds).

– 10:23:30: GMT @ T+02:05Solid Rocket Booster (SRB) separation. Discovery is at the altitude of 47.18 km, 44.57 km down range from the KSC, traveling at 5 870.9 km/h (Mach 4).


Solid Rocket Booster Separation - Credit: NASA TV

– 10:22:24 GMT @ T+00:59 – Max-Q (the point of the greatest dynamic pressure).

– 10:22:17 GMT @ T+00:52 –Throttle up back to 104.5% engine power level.

– 10:22:10 GMT @ T+00:45 – Mach 1.

– 10:22:04 GMT @ T+00:39 – Throttle down from 104.5% to 72.0% engine power level at Mach 0.9.

– 10:21:44 GMT @ T+00:19 – Roll maneuver finished.

– 10:21:35 GMT @ T+00:10 – Start the roll program.

– 10:21:25 GMT @ T-00:00 – Lift-off. Solid Rocket Booster (SRB) ignition and lift-off of the Space Shuttle Discovery on the STS-131 (ISS assembly flight 20A) mission to the International Space Station (ISS).


Lift-off of Space Shuttle Discovery - Credit: NASA TV

– 10:21:18 GMT @ T-00:06.6 (and 06.48, 06.36) – The three Space Shuttle Main Engines (SSME) start.

Space Shuttle Main Engines ignite

Space Shuttle Main Engines ignite - Credit: NASA TV

– 10:21:14 GMT @ T-00:09 – The hydrogen burn-off system begins to eliminate free hydrogen exhausted into the main engine nozzles during the start sequence to prevent small, but potentially dangerous, explosions when the main engines ignite.

The hydrogen burn-off system

The hydrogen burn-off system is activated - Credit: NASA TV

– 10:21:10 GMT @ T-00:15 – The Sound Suppression Water System has been activated to protect Discovery and the launch pad from acoustical energy and rocket exhaust reflected from the flame trench and Mobile Launcher Platform during launch.

– 10:20:54 GMT @ T-00:31 – Auto-sequence start. Discovery’s on-board computers have primary control of all vehicle’s critical functions.

10:12:25 GMT: The countdown clock resumes at T-9min and counting.

T-9 minutes and counting

T-9 minutes and counting - Credit: NASA TV

08:21 GMT: Shuttle Discovery’s hatch has been closed and latched for flight, the six STS-131 astronauts are strapped into their seats.

The countdown clock resumes at T-3hr and counting.

The STS-131 crew leaves the crew quarters at the Operations and Checkout Building and boards the Astrovan to head to the Pad 39A - Credit: NASA

– The STS-131 crew leaves the crew quarters at the Operations and Checkout Building and boards the Astrovan to head to the Pad 39A.

– Final inspection team is on the pad looking for ice & frost buildup on the External Tank.

[04:21] GMT: The shuttle tanking went into a stable replenish and the countdown entered a 2.5 hour long inbuilt hold at T-3 hours.

– The liquid hydrogen tanking has reached 98% and will transition from fast-full to top-off at 2700 l per minute.

– Liquid oxygen tanking changes to fast-fill mode at almost 6,000 l per minute. Liquid hydrogen is also in fast-fill phase adding almost 32,000 liters every minute into the external tank (ET).

– Launch teams began liquid oxygen tanking in the slow-fill phase adding 1,200 liters every minute.

01:28 (April 05) GMT: Fueling of the External Tank began with liquid hydrogen (at 20K) started in the slow-fill mode. Liquid oxygen (at 90.188 K) will follow at ~02:00 GMT. The 3-hr fuel+oxidizer loading process for Discovery’s 3 main engines will provide the shuttle with fuel for its 8 1/2 min ride to orbit.

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Matt Barnes

Thanks for this. I was there for launch as a spectator at the KSC. It was a high point of my life. One question for you: I remembered that there was a failure in one of the onboard systems in the last few moments before launch and it had to be picked up by a sub-system. Do you happen to know what that was? I can’t recall and would like to get it right.

Many thanks,

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